Thermal testing of the boiler is carried out in order to establish compliance of its characteristics with the technical specifications for delivery (customer requirements), that is, to determine the suitability of the tested boiler for the ship's power plant. Tests are carried out at full, maximum, minimum and partial loads with manual and automatic control.
During testing, the following is determined:
– boiler specifications – fuel consumption, steam output, parameters of the steam produced by the boiler, saturated steam humidity, efficiency, gas-air resistance, excess air coefficient, as well as thermochemical characteristics of the boiler (salinity of boiler water, superheated steam, purge mode, etc. .);
– reliability of operation of the boiler as a whole and all its elements, which is judged by the temperature conditions of the elements, the strength of the boiler structure, the density of the fittings and casing, the quality brickwork and insulation, stability of the combustion process and maintaining the water level in the steam-water collector, etc.;
– maneuverability characteristics of the boiler – duration of wiring, lifting and unloading, stability of steam parameters;
– operational features of the boiler – convenience, accessibility and duration of disassembly and assembly of individual parts of the boiler (necks, manhole valves, internal parts of the steam-water manifold, PP manifold, etc.) accessibility of cleaning and inspection, maintainability (convenience of plugging failed tubes, repairing boiler parts , PP, VE, VP), efficiency of soot blowers, ease of monitoring the operation of the boiler.
Thermal testing is carried out in two stages:
1) commissioning - at the manufacturer’s stand, during which all control and protection systems are tested, the combustion process and water regime are adjusted, the obtained characteristics are checked for compliance with the design ones, and the boiler is prepared for acceptance tests;
2) warranty and delivery - in conditions where the operating features of the ship's power plant (SPP) for which the boiler under test is intended are comprehensively taken into account; These tests are performed at nominal and maximum loads, as well as at fractional modes corresponding to 25, 50, 75 and 100% fuel consumption loads. Thermotechnical tests of recovery boilers are carried out during testing of the control system.
Commissioning tests are preceded by detailed inspections of the boiler and its servicing systems, as well as a steam test. Its purpose is to check the density and strength of the boiler and its individual parts, as well as the deformation of the boiler elements during gradual heating. Based on the results of the steam test, safety valves are adjusted.
Before the start of acceptance tests, the boiler must operate without cleaning for at least 50 hours. Based on the results of acceptance tests, all characteristics of the boiler are finally established and the documentation is adjusted; technical specifications for delivery, technical data sheet, description and operating instructions.
The diagram of the bench installation for conducting thermal and thermochemical tests is shown in Fig. 8.1.
Steam from the boiler steam-water header 1 enters through a throttle-moistening device 2 to the capacitor 6 , where the condensate pump comes from 7 directs condensate to measuring tanks 9 . Usually one tank is filled and the other is pumped 10 the boiler is powered. Arrow 5 The boiler is fed with additional water. To make it possible to change the chemical composition of the boiler water, measuring tanks are available 5 , which are filled with solutions of various chemical reagents. Reagents can also be supplied directly to the boiler using special dispensers.
To provide the boiler with fuel and measure its consumption, there are measuring fuel tanks 13 , one of which is filled with fuel, and from the other fuel is supplied through filters 15 pump 14 to the nozzle. When the boiler operates on fuel oil and motor fuels, a fuel heater and a recirculation system are used to preheat the fuel to a temperature of 65–75°C. Air enters the boiler from a fan 18 .
A steam sampling device is installed on the main steam line, from which a steam sample is sent to the condenser 3 . The resulting condensate goes directly into the salinity meter or into the flask 4 and then to the laboratory for chemical analysis. The results of the analysis allow us to determine the moisture content of the steam. Boiler water sampling is carried out through the refrigerator 17 , from which cooled water is drained into a vessel 16 for further chemical analysis. The composition of combustion products is determined using a gas analyzer. These data are used to calculate the excess air coefficient. Water removed from the boiler by upper and lower blowing through the refrigerator 12 enters the measuring container 11 . Parameters of steam, feed water, air, products
Symbols of devices
<жиннь/й монометр для замера (г) давлений пара р } топлива р?л
TJ~ shaped nanometer For measuring ^2 static pressures in the air box b. in Vtopka. D) Vdymna-
®еь, А Thermometers (thermocouples) for is a measure of air temperatures tr B j7ion/lu-va t 7 fi, flue gases й^ x.
Rice. 8.1. Schematic diagram of a stand for conducting thermal and thermochemical tests of boilers
combustion is measured using instruments, some of which have devices for automatically recording readings. In order to determine the thermal and operational characteristics of the boiler over a wide range of loads, its balance tests are carried out under stationary operating conditions.
The steam output of the boiler is determined by the flow of feed water at a constant water level in the steam-water manifold and tightly closed upper and lower blowing valves, under these conditions 
.
Feedwater and fuel flow rates are measured using pre-tared measuring tanks. To do this, it is necessary to measure the change in level 
water (fuel) in the tank during 
.
Then the consumption of feedwater (fuel) can be calculated using the formula
Steam consumption is also determined using flow metering diaphragms installed on the main steam line. The temperature of water, fuel, air is measured with technical mercury thermometers, and the temperature of exhaust gases is measured with thermocouples; pressure of steam, feed water and fuel - with spring pressure gauges, and pressure in the gas-air path - with U-shaped water pressure gauges. The readings of all stand instruments are recorded using a common signal after 10–15 minutes. The duration of reaching the stationary mode is 2 hours. The mode is considered stationary (steady) if the readings of the instruments measuring the main parameters do not go beyond the permissible deviations from the average value. During measurements, deviations are allowed: steam pressure ±0.02 MPa, gas and air pressure ±20 Pa; temperature of feed water and flue gases ±5°С. The average values of instrument readings over time are found as the arithmetic average over the test period. Values that differ from the more acceptable average are not taken into account. If the number of such readings exceeds 17% of the total number of measurements taken, then the experiment is repeated.
The efficiency of the boiler is determined by formulas (3.13) and (3.14), heat losses with flue gases 
and from chemical underburning 
formulas (3.3), (3.24), (3.26) and (3.27), and losses to the environment 
, calculated using the heat balance equation
To calculate the excess air coefficient a, gas analysis data and calculated dependencies (2.35)–(2.41) are used. Based on the test results, graphs are drawn (Fig. 8.2), which represent dependences on fuel consumption IN. This full scope of testing is intended for newly developed boilers. For serial samples, the volume of testing can be reduced, which is provided for by special programs.
Highly economical and safe operation of a boiler on a ship can be ensured provided that all requirements of the USSR Register, which supervises their implementation, are met. This supervision begins with the consideration of technical documentation, drawings, calculations, technological maps, etc. All main, auxiliary and recovery boilers, their superheaters, economizers with an operating pressure of 0.07 MPa or more are subject to supervision.
Representatives of the USSR Register subject boilers to inspection, which may coincide in time with the inspection of the vessel as a whole or be carried out independently. They are initial, regular and annual.
Initial the survey is carried out in order to establish the possibility of assigning a class to the vessel (the technical condition and year of construction of the vessel, mechanisms, including boilers, are taken into account), another, – to renew the class of the vessel and check the compliance of the technical condition of mechanical equipment and boilers with the requirements of the USSR Register; annual inspection is necessary to control the operation of mechanisms and boilers. After repair or accident, the ship undergoes an extraordinary survey. During surveys, a representative of the Register may carry out internal and external inspections, hydraulic tests of boilers, adjustment and testing for operation of safety valves; inspection of means for preparing and supplying feed water, fuel and air, fittings, instrumentation, automation systems; checking protection operation, etc.
Hydraulic test test pressures are usually 
, but no less than 
MPa ( 
working pressure). For superheaters and their elements 
if they operate at a temperature 
, equal to 350°C and above.
|
|
0.1 0.2 0.3 V,kg/s
Rice. 8.2. Boiler characteristics
The steam boiler and its elements (PP, VE and PO) are maintained at test pressure for 10 minutes, then the pressure is reduced to operating pressure and the inspection of the boiler and its fittings continues. Hydraulic tests are considered successful if the test pressure does not decrease within 10 minutes, and upon inspection no leaks, visible changes in shape or residual deformation of the boiler parts are detected.
The safety valves must be adjusted to the following opening pressures: for 
MPa; 
For 
MPa.Maximum pressure when the safety valve operates 
.
During the inspection, external inspections of boilers are carried out along with pipelines, fittings, mechanisms and systems at operating steam pressure.
The results of the survey are entered into the register book of the steam boiler and the main steam pipeline, which is issued by the inspector of the USSR Register during the initial survey of each boiler.
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DECISION of the Gosgortekhnadzor of the Russian Federation dated 06/11/2003 88 ON APPROVAL OF RULES FOR THE DESIGN AND SAFE OPERATION OF STEAM AND... Relevant in 2018
5.14. Hydraulic tests
5.14.1. All boilers, superheaters, economizers and their elements after manufacture are subject to hydraulic testing.
Boilers, the manufacture of which is completed at the installation site, transported to the installation site in individual parts, elements or blocks, are subjected to hydraulic testing at the installation site.
The following are subject to hydraulic testing in order to check the density and strength of all elements of the boiler, superheater and economizer, as well as all welded and other connections:
a) all pipe, welded, cast, shaped and other elements and parts, as well as fittings, if they have not passed hydraulic tests at the places of their manufacture; hydraulic testing of the listed elements and parts is not mandatory if they are subjected to 100% control by ultrasound or other equivalent non-destructive flaw detection method;
b) assembled boiler elements (drums and manifolds with welded fittings or pipes, blocks of heating surfaces and pipelines, etc.). Hydraulic testing of manifolds and pipeline blocks is not mandatory if all their constituent elements have been subjected to hydraulic testing or 100% ultrasonic testing or other equivalent non-destructive testing method, and all welded joints performed during the manufacture of these prefabricated elements have been tested by non-destructive testing (ultrasound or radiography) ) along its entire length;
c) boilers, steam superheaters and economizers after completion of their manufacture or installation.
It is allowed to carry out hydraulic testing of individual and prefabricated elements together with the boiler, if under the conditions of manufacture or installation it is impossible to test them separately from the boiler.
5.14.2. The minimum value of test pressure Ph during hydraulic testing for boilers, superheaters, economizers, as well as pipelines within the boiler is accepted:
at a working pressure of no more than 0.5 MPa (5 kgf/cm2)
Ph = 1.5 p, but not less than 0.2 MPa (2 kgf/cm2);
at operating pressure more than 0.5 MPa (5 kgf/cm2)
Ph = 1.25 p, but not less than p + 0.3 MPa (3 kgf/cm2).
When carrying out hydraulic testing of drum boilers, as well as their superheaters and economizers, operating pressure the pressure in the boiler drum is taken, and for drumless and once-through boilers with forced circulation - the feed water pressure at the boiler inlet, established by the design documentation.
The maximum value of the test pressure is established by strength calculations according to the normative documents agreed with the State Mining and Technical Supervision Authority of Russia.
The designer is obliged to select a test pressure value within the specified limits that would ensure the greatest detection of defects in the element subjected to hydraulic testing.
5.14.3. Hydraulic testing of the boiler, its elements and individual products is carried out after heat treatment and all types of control, as well as correction of detected defects.
5.14.4. The manufacturer is obliged to indicate in the installation and operating instructions the minimum wall temperature during hydraulic testing during boiler operation based on the conditions for preventing brittle fracture.
Hydraulic testing should be carried out with water at a temperature not lower than 5 and not higher than 40 degrees. C. In cases where this is necessary due to the conditions of the metal characteristics, the upper limit of water temperature can be increased to 80 degrees. C in accordance with the recommendation of a specialized research organization.
The temperature difference between the metal and the ambient air during testing should not cause moisture to form on the surfaces of the test object. The water used for hydraulic testing must not pollute the object or cause intense corrosion.
5.14.5. When filling a boiler, autonomous superheater, or economizer with water, air must be removed from the internal cavities. The pressure should be increased evenly until the test pressure is reached.
The total pressure rise time is indicated in the installation and operation instructions for the boiler; If there is no such indication in the instructions, then the pressure rise time should be at least 10 minutes.
The holding time under test pressure must be at least 10 minutes.
After holding under test pressure, the pressure is reduced to working pressure, at which all welded, rolled, riveted and detachable joints are inspected.
The water pressure during testing must be monitored by two pressure gauges, one of which must have an accuracy class of at least 1.5.
The use of compressed air or gas to increase pressure is not permitted.
5.14.6. The object is considered to have passed the test if no visible residual deformations, cracks or signs of rupture, leaks are detected in welded, flared, detachable and riveted joints and in the base metal.
In flared and detachable joints, the appearance of individual drops is allowed, which do not increase in size with time.
5.14.7. After the hydraulic test, it is necessary to ensure that the water is removed.
5.14.8. The hydraulic test carried out at the manufacturer must be carried out on a special test bench that has appropriate fencing and meets the safety requirements and instructions for conducting hydraulic tests, approved by the chief engineer of the organization.
5.14.9. It is permissible to carry out a hydraulic test simultaneously for several elements of the boiler, superheater or economizer, or for the entire product as a whole, if the following conditions are met:
a) in each of the combined elements, the test pressure value is not less than that specified in clause 5.14.2;
b) continuous testing of the base metal is carried out using non-destructive methods and welded joints those elements in which the test pressure value is taken to be less than those specified in clause 5.14.2.
MINISTRY OF ENERGY AND ELECTRIFICATION OF THE USSRPRODUCTION ASSOCIATION FOR SETTING UP, IMPROVING TECHNOLOGY AND OPERATION OF POWER PLANTS AND NETWORKS "SOYUZTEKHENERGO" METHODOLOGICAL INSTRUCTIONS FOR TESTING HYDRAULIC STABILITY DIRECT-FLOW ENERGY AND WATER HOT BOILERS
SOYUZTEKHENERGO
Moscow 1989 Contents DEVELOPED by the Moscow head enterprise of the Production Association for setting up, improving technology and operating power plants and networks "Soyuztechenergo" CONTRACTORS V.M. LEVINSON, I.M. GIPSHMAN APPROVED BY "Soyuztechenergo" 04/05/88 Chief engineer K.V. SHAHSUVAROV Validity period set
from 01/01/89
until 01/01/94. These Guidelines apply to stationary once-through steam power boilers and hot water boilers with absolute pressure from 1.0 to 25.0 MPa (from 10 to 255 kgf/cm2). Guidelines do not apply to boilers: with natural circulation; steam-water-heating; locomotive units; waste heat boilers; energy-technological, as well as other boilers for special purposes. Based on the experience accumulated in Soyuztekhenergo and related organizations, methods for testing boilers in stationary and transient modes are specified and described in detail in order to check the conditions hydraulic stability of steam-generating heating surfaces of direct-flow steam boilers or screen and convective heating surfaces of hot water boilers. Hydraulic stability tests are carried out both for newly created (head) boilers and for those in operation. Tests make it possible to check the compliance of hydraulic characteristics with the calculated ones, assess the influence of operational factors and determine the boundaries of hydraulic stability. The guidelines are intended for the production departments of the Soyuztechenergo PA conducting tests of boiler equipment according to clause 1.1.1.06 of the “Price list for experimental adjustment and improvement work technology and operation of power plants and networks", approved by Order of the Minister of Energy and Electrification of the USSR No.
313 dated October 3, 1983. The guidelines can also be used by other commissioning organizations performing tests of the hydraulic stability of once-through boilers.
1. KEY INDICATORS
1.1. Determination of hydraulic stability: 1.1.1. The following indicators of hydraulic stability are subject to determination: thermal-hydraulic sweep; aperiodic stability; pulsation stability; stagnation of movement. 1.1.2. Thermal-hydraulic testing is determined by the difference between the flow rates of the medium in individual parallel elements of the circuit and the outlet temperatures in the same elements compared to the average values in the circuit. 1.1.3. Violation of aperiodic stability associated with the ambiguity of hydraulic characteristics is determined by: an abrupt decrease in the flow rate of the medium in individual elements of the circuit (at a rate of 10%/min or more) with a simultaneous increase in the outlet temperature in the same elements compared to the average values in the circuit; or when reversing the movement by changing the sign of the flow rate of the medium in individual elements to the opposite, with an increase in the temperature at the inlet to these elements. On boilers operating with subcritical pressure in the circuit, an increase in temperature at the outlet of the elements may not be observed. 1.1.4. Violation of pulsation stability is determined by pulsations of medium flow (as well as temperatures) in parallel elements of the circuit with a constant period (10 s or more) regardless of the amplitude of the pulsations. Flow pulsations are accompanied by pulsations in the temperature of the pipe metal in the heated zone and the temperature at the outlet of the elements (at subcritical pressure the latter may not be observed). 1.1.5. Stagnation of movement is determined by a decrease in the flow rate of the medium (or the pressure drop on the flow measuring devices) in individual elements of the circuit to zero or to values close to zero (less than 30% of the average flow rate). 1.1.6. It is allowed in cases provided for by the standard method of hydraulic calculation [1], when violations of hydraulic stability of one type or another are obviously impossible, not to determine the corresponding indicators. For example, there is no need to check aperiodic stability for purely lifting motion in a circuit. Checking pulsation stability is not required at supercritical pressure, in the absence of subcooling to boiling at the inlet circuit, as well as for hot water boilers. At supercritical pressure, most circuits do not require a check for stagnation, with the exception of certain cases (heavily slagging firebox risers, shadowed corner pipes, etc.). 1.1.7. The following indicators required to assess the conditions and boundaries of hydraulic stability are also subject to determination: flow rate and average mass velocity of the medium in the circuit, G kg/s and wr kg/(m 2 × s); temperature of the medium at the inlet and outlet of the circuit, tVx And tYoux ° C; maximum temperature at the outlet of the circuit elements, ° C; subheat to boiling, D tunder ° C (for hot water boilers); medium pressure at the outlet of the circuit (or at the inlet to the circuit, or at the end of the evaporative part of the steam boiler), for hot water boilers - at the inlet and outlet of the boiler, R MPa; flow rate and mass velocity of the medium in the circuit elements, Gel kg/s and ( wr)el kg/(m 2 × s); heat perception (enthalpy increment) in the circuit, D i kDk/kg; metal temperature of individual pipes in the heated zone, t vtn ° C. 1.1.8. When determining individual (from among those specified in clause 1.1.1) indicators of hydraulic stability or during tests of a research nature, additional indicators can also serve as: pressure drop in the circuit (from inlet to outlet), D R k kPa; temperature at the inlet to the circuit elements, tel° C; thermal scanning coefficients, rq; hydraulic reaming, rq; uneven heat perception, hT. 1.2. In necessary cases (for new or reconstructed circuits, during a preliminary assessment of stability, to clarify the type, nature and causes of identified violations, etc.), the hydraulic characteristics of the corresponding circuits are calculated or the reliability margins are assessed based on factory calculations. The calculation of hydraulic characteristics is carried out on a computer (using programs developed at Soyuztechenergo) or manually according to [1]. Based on the calculated data and preliminary assessment of the hydraulic stability of individual circuits, the least reliable of them are more fully equipped with measuring instruments, the tasks and test program are specified.2. ACCURACY INDICATORS OF DETERMINED PARAMETERS
Indicators of the thermal and hydraulic performance of the circuit are determined by measuring temperature, flow and pressure in the circuit and its elements. The error of these indicators obtained as a result of processing measurement data should not exceed the values indicated in table. 1. Table 1|
Name |
Error |
Steam boilers |
Hot water boilers |
Flow rate and average mass velocity of the medium in the circuit, % | Temperature at the inlet and outlet of the circuit, °C | Temperature at the inlet and outlet of the circuit elements, °C | Subheating to boiling, °C | Pressure at the inlet and outlet of the circuit, % | Pressure drop in the circuit (from inlet to outlet), % | Note. The flow rate of the medium in the circuit elements, the enthalpy increment, as well as the coefficients of thermal and hydraulic expansion and unevenness of heat perception are determined without standardization of accuracy. The temperature of the metal in the heated zone is determined without standardization of accuracy in accordance with methodological instructions for departmental full-scale tests of the temperature regime of the heating surfaces of steam and hot water boilers. |
3. TEST METHOD
3.1. Available regulatory materials, primarily [1], make it possible to perform an approximate calculation of the main indicators of the hydraulic stability of the boiler. Calculations include, however, a number of parameters and coefficients that can be established with the required accuracy only experimentally, including: actual temperatures environment along the tract; enthalpy increment in the circuit, pressure, pressure drop (circuit resistance); temperature distribution among elements; values of parameter deviations in dynamic modes of real operation; coefficients of thermal, hydraulic testing and unevenness of heat absorption, etc. On the other hand, calculation methods cannot cover the entire variety of specific design solutions used in boilers, especially newly created ones. In view of this, carrying out full-scale industrial tests serves as the main method for determining the hydraulic stability of steam and hot water boilers boilers 3.2. Depending on the purpose of the work and the required volume of measurements, tests according to the Price List for experimental adjustment work and work to improve the technology and operation of power plants and networks are carried out in two categories of complexity: 1 - checking an existing or newly developed calculation and testing methodology; or identifying operating conditions for new hydraulic circuits that have not yet been tested in practice; or checking the boiler heating surfaces on a prototype sample; 2 - tests of one heating surface of the boiler. 3.3. Tests are carried out in stationary and transient modes; in the operational or extended range of boiler loads; if necessary, also in kindling modes. In addition to planned experiments, observations are carried out in operating modes. 3.4. Hydraulic stability indicators are determined for the following types of boiler hydraulic circuits: pipe packages and panels with parallel-connected heated pipes, inlet and outlet manifolds; heating surfaces with parallel-connected pipe packages or panels, inlet and outlet pipelines, inlet and outlet common manifolds; complex circuits with parallel connected subflows, which include heating surfaces, connecting pipelines, transverse bridges and other elements. 3.5. In double-flow boilers, subject to a symmetrical design, it is allowed to perform tests only for one controlled flow with monitoring of operating parameters for both flows and for the boiler as a whole.4. MEASUREMENT SCHEME
4.1. The experimental control scheme includes special experimental measurements that provide experimental values of temperatures, flow rates, pressures, pressure drops in accordance with the test objectives. Experimental control measuring instruments are installed on both or one controlled flow of the boiler (see clause 3.5). Standard control measuring instruments are also used. 4.2. The scope of experimental control includes measurements of the following main parameters: - medium temperatures along the steam-water path (for both flows), at the inlet and outlet of all sequentially connected heating surfaces in the economizer-evaporation part of the path (before the built-in valve, separator, etc.), as well as in the steam superheating part and in the reheating path (before and after injections and at the outlet of the boiler). For this purpose, submersible thermoelectric converters (thermocouples) for experimental control are installed, or standard measuring instruments are used. Measuring instruments for experimental control are installed on the surface under test. The boiler is equally equipped with measuring instruments along the steam-water path even if the tests cover only one or two heating surfaces. Without this, it is impossible to properly determine the influence of regime factors; - ambient temperatures at the outlet (and, if necessary, also at the inlet) of subflows and individual panels in the circuit (surface) under study. Measuring instruments are installed in outlet pipes (submersible thermocouples; the use of surface thermocouples is allowed if their installation sites are carefully insulated). They cover all parallel elements. With a large number of parallel panels, it is allowed to equip some of them, including the middle ones and the most non-identical ones (in design and heating); - temperatures at the outlet of the coils (heated pipes) of the test surfaces; in necessary cases (if there is a danger of overturning, traffic stagnation) - also at the entrance. This is the most widespread type of measurement in terms of quantity. Measuring instruments are installed in the unheated zone of the coils (surface thermocouples); as a rule, in the same panels where outlet temperature measurements are provided. In multi-pipe panels, thermocouples are installed in “middle” pipes evenly in width (in increments of several pipes) and in pipes with thermal and structural non-identity (extreme and adjacent to them; enveloping burners; differing in connection to collectors, etc.). In the absence in the coils of the test surface of the unheated zone (as is the case, for example, on hot water boilers, according to their design), to directly measure the temperature, submersible thermocouples are installed at the outlet of these coils; - feed water flow along the streams of the steam-water path (allowed for one stream if experimental control is installed on one stream). The measuring device is usually a standard standard diaphragm in the supply line, to which, in parallel to the standard water meter, an experimental control sensor is connected; - flow rate and mass velocity of the medium at the entrance to the subflows of the circuit (in each) and in the panel (selectively). TsKTI or VTI pressure tubes are installed on the supply pipes in panels, which, according to a preliminary assessment, are the most dangerous in case of hydrodynamic disturbances, and in coordination with the installation of thermocouples; - flow rate and mass velocity of the medium at the inlet to the coils. TsKTI or VTI pressure tubes are installed on the inlet sections of pipes in an unheated area. The number and placement of measuring instruments is determined by specific conditions, including “average” and most dangerous coils, in accordance with the installation of thermocouples at the outlet of the coils, as well as temperature inserts (i.e. on the same coils). Means for measuring flow rates in the elements of the circuit must be placed in such a way that they, in total, with the minimum possible number, reflect all the instability of stability in the circuit expected according to a preliminary assessment; - pressure in the steam-water path. Selecting devices for measuring pressure are installed at characteristic points of the tract, including at the outlet of the test surface, at the end of the evaporation part (before the built-in valve); for a hot water boiler - at the boiler outlet (as well as at the inlet); - pressure drop (hydraulic resistance) of the subflow, or heating surface, or a separate section of the circuit under test. Selected devices for measuring pressure drop are installed in special cases: during research tests, when checking the compliance of calculated data with actual data, when there are difficulties in classifying instability, etc.; - temperature of the pipe metal in the heated zone. Temperature or radiometric inserts for measuring metal temperature are installed in the test surfaces, mostly in the flow, where most of the measurements are taken, but also control inserts for other flows. Inserts are placed around the perimeter and height of the firebox in the area of maximum thermal stress and expected highest metal temperatures. The choice of pipes for installing inserts should be linked to the installation of temperature and flow measurements across the coils. 4.3. The experimental control measuring instruments according to clause 4.2 apply to purely direct-flow boiler circuits. In the complex branched hydraulic circuits inherent in modern boilers, other necessary measuring instruments are installed in accordance with the specific design features. For example: a circuit with parallel subflows and a transverse hydrodynamic jumper - temperature measurement before and behind the insertion of the jumper on both subflows; flow measurement via jumper; measuring the pressure difference at the ends of the jumper; a boiler with medium recirculation through a screen system (pumping or non-pumping) - measuring the temperature of the medium in the selections of the recirculation circuit upstream and downstream of the mixer; measurement of medium flow in the recirculation circuit selections and through the screen system (behind the mixer); measurement of pressures (pressure differences) at nodal points of the circuit, etc. 4.4. Indicators of the boiler operation as a whole, indicators of the combustion mode, as well as general unit indicators are recorded using standard control devices. 4.5. The volume, as well as the features of the measurement scheme, are determined by the goals and objectives of the tests, the category of complexity, the steam output and parameters of the boiler, the design of the boiler and the circuit under test (radiation or convective surfaces, all-welded and smooth-tube screens, type of fuel, etc.). For example, when testing NRF on a gas-oil boiler of a 300 MW monoblock, the measurement scheme may include from 100 to 200 temperature measurements in an unheated zone, 10-20 temperature inserts, approximately 10 measurements of flow rates and pressures; when testing a hot water boiler - from 50 to 75 temperature measurements, 5-8 temperature inserts, approximately 5 flow and pressure measurements. 4.6. All experimental control measurements must be submitted for registration using self-recording secondary instruments. Secondary devices will be placed on the experimental control panel. 4.7. A list of measurements, their locations in the boiler and a breakdown by instrument are given in the documentation for the measurement scheme. The documentation also includes an instrument switching diagram, a sketch of the panel, a diagram of the placement of temperature inserts, etc. Approximate measurement diagrams in relation to tests of the TGMP-314 NRF boiler and to tests of the KVGM-100 water heating boiler are shown in Fig. 12.
Rice. 1. Scheme of experimental control of the NRF boiler TGMP-314: 1-3 - panel numbers; I-IV - numbers of moves; - immersion thermocouple; - surface thermocouple; - temperature insert; - pressure tube TsKTI; - pressure selection; - differential pressure selection.
Number of surface thermocouples: at the input of the front half-flow coils A: I stroke - 16; 2nd turn - 12; III move - 18; the same for rear half-flow A: I stroke - 12; 2nd move - 8; III - move - 8; IV move - 8 pcs.; on jumper A - 6 pcs.; on jumper B - 4 pcs. . Notes: 1. The diagram shows measurements along flow A. Submersible thermocouples are installed along flow B similar to flow A. 2. Measurements along flow B are similar to flow A. 3. Numbering of panels and coils is from the boiler axes. 4. Measurements of temperatures and flow rates along the steam-water path are carried out in accordance with the boiler instrumentation and control diagram.
Rice. 2. Scheme of experimental control of the KVGM-100 water heating boiler: - upper collector; - lower collector; - surface thermocouples on pipelines; - the same on pipes and risers; - immersion thermocouples in envelope coils; - temperature inserts at the mark of the upper tier of burners; - differential pressure selection;
1 - rear screen of the convective part: 2 - side screen of the convective part; 3 - screens of the convective part; 4 - package I; 5 - packages II, III; 6 - intermediate firebox screen; 7 - firebox side screen; 8 - front screen
5. TESTING MEANS
5.1. During testing, standardized measuring instruments must be used, metrologically ensured in accordance with GOST 8.002-86 and GOST 8.513-84. Types and characteristics of measuring instruments are selected in each specific case depending on the equipment being tested, the required accuracy, installation and installation conditions, ambient temperature and from other external influencing factors. Measuring instruments used during testing must have valid verification marks and technical documentation indicating their suitability and provide the required accuracy. 5.2. Requirements for measurement accuracy: 5.2.1. The permissible error in measuring the initial values, ensuring the required accuracy of the determined indicators (see Section 2), should not exceed for: temperature of water, steam, metal in an unheated zone: steam boiler - 10 ° C; hot water boiler - 5 ° C; water flow and steam - 5%; water and steam pressure - 2%. 5.2.2. The requirements specified in this section refer to type tests of boilers. When conducting tests on experimental, or modernized, or fundamentally new equipment, or when checking new test methods, the test program must stipulate additional requirements for measuring instruments and accuracy characteristics. 5.3. To measure parameters that do not require accuracy standards during testing (see Section 2), indicators can be used. The specific types of indicators used are specified in the test program. 5.4. Temperature measurement: 5.4.1. Temperature is measured using thermoelectric converters (thermocouples). When making measurements at relatively low temperatures that require high accuracy, thermoelectric thermometers (resistance thermometers) in accordance with GOST 6651-84 can also be used. Depending on the range of measured temperatures, XA thermocouples are used (at the upper limit of measured temperatures 600-800 ° C) or XK (400-600°C) wire diameter 1.2 or 0.7 mm. It is recommended to insulate thermionic wires with silica or quartz filament by double winding. Detailed characteristics of thermocouples are contained in the specialized literature [2, etc.]. 5.4.2. To directly measure the temperature of water and steam, standard immersion thermocouples of the TXA type are used. Submersible thermocouples are installed on a straight section of the pipeline in a sleeve welded into the pipeline. The length of the element is selected depending on the diameter of the pipeline based on the location of the working end of the element thermocouple along the flow axis. The minimum length of a standard element is 120 mm. In small-diameter pipelines, submersible thermocouples of non-standard manufacture can be installed, but in compliance with the installation rules (for example, when testing water heating boilers, see paragraph 4.2.3). 5.4.3. Surface thermocouples are installed outside the heating zone on the outlet (or inlet) sections of the coils, near the collector, as well as on the outlet (or inlet) pipes of the panels. The connection to the metal of the pipe (the working end of the thermocouple) is recommended to be made by caulking the thermoelectrodes into a metal boss (separately in two holes), which in turn is welded to the pipe. The working end of the thermocouple can also be made by caulking the thermocouple into the body of the pipe. The initial section of the insulated surface thermocouple, at least 50-100 mm long from its working end, must be tightly pressed to the pipe. The thermocouple installation site and the pipeline in this area must be carefully covered with thermal insulation. 5.4.4. Measurement of pipe metal temperatures in the heated zone (using Soyuztekhenergo temperature inserts with a thermocouple cable KTMS or XA thermocouples, or TsKTI radiometric inserts with XA thermocouples) should be carried out in accordance with the “Methodological instructions for departmental full-scale tests of the temperature regime of screen heating surfaces of steam and hot water boilers.” Inserts are not standardized measuring instruments and serve as indicators when testing hydraulic stability (see clause 5.3). 5.4.5. As secondary devices when measuring temperature using thermocouples, self-recording electronic multipoint potentiometers with analog, digital or other form of recording (continuous or with a recording frequency of no more than 120 s) are used. In particular, KSP-4 devices of accuracy class 0.5 by 12 points are used (with a cycle of 4 s and a recommended tape drawing speed of 600 mm/h). Multi-channel measuring devices with access to digital printing and punching devices are also used. As secondary devices for For temperature measurements using resistance thermometers, DC measuring bridges are used. 5.5. Measuring water and steam flow: 5.5.1. Flow is measured using flow meters with orifices (measuring diaphragms, nozzles) in accordance with the “Rules for measuring the flow of gases and liquids using standard orifices” RD 50-213-80. Flow meters with restriction devices are installed on pipelines with a single-phase medium with an internal diameter of at least 50 mm. The flow metering device, its installation and connecting (pulse) lines must comply with the specified rules. 5.5.2. In cases where additional pressure losses are not allowed, as well as on pipelines with an internal diameter of less than 50 mm, flow meters with pressure tubes (Pitot tubes) designed by TsKTI or VTI are installed as a flow indicator [2]. TsKTI rod tubes, like round VTI tubes, have a small non-recoverable pressure loss. Pressure tubes are suitable only for the flow of a single-phase medium. The design of pressure tubes TsKTI and VTI with a description and flow coefficients is given in Appendix 1 and in Fig. 3, 4.
Rice. 3. Designs of pressure tubes for measuring water circulation rates 
Rice. 4. Values of flow coefficients for rod and cylindrical tubes 5.5.3. Differential pressure gauges (GOST 22520-85) are used as primary transducers (sensors) when measuring flow rates. Connecting lines are laid from the measuring device to the sensor in accordance with the rules of RD 50-213-80. 5.6. Selection of signals based on static pressure is carried out through holes (fittings) in pipelines or manifolds of the heating surface outside the heating zone. Sampling devices should be installed in places protected from the dynamic effects of the work flow. Pressure gauges with an electrical output (GOST 22520-85) are used as sensors. 5.7. The pressure difference is measured using static pressure taps at the beginning and end of the measured section of the circuit, which are carried out according to the type of pressure measurement. Differential pressure gauges are used as sensors. 5.8. The type and accuracy class of sensors and secondary instruments used in measuring flow, differential pressure and pressure are given in Table. 2. Table 2 Note. To measure flow, instead of DME and Sapphire 22-DC sensors, which provide a linear differential pressure signal, DMER and Sapphire 22-DC sensors with NIR (with a square root extraction block and transition to the flow scale) can be used. Since testing scales are usually non-standard and must be suitable for various conditions, sets with a linear scale of differences (with further recalculation during processing) often turn out to be more convenient. 5.9. Choice
sensors according to the pressure differential measurement range is made from a number of values in accordance with GOST 22520-85. Approximately used values: feed water consumption - 63; 100; 160 kPa (0.63; 1.0; 1.6 kgf/cm2);
water flow (speed) in panels and coils - 1.6; 2.5; 4.0; 6.3 kPa (160; 250; 400; 630 kgf/cm2); for boilers SKD-40 MPa (400 kgf/cm 2), for boilers VD-16; 25 MPa (160; 250 kgf/cm2); for hot water boilers - 1.6; 2.5 MPa (16; 25 kgf/cm2). 5.10. The lower guaranteed limit of measurement for flow sensors (LMED) is 30% of the upper limit. In cases where during testing it is necessary to cover a large range of flow rates (or pressures), including small and starting loads of the boiler, two sensors are connected in parallel to the measuring device at different measurement limits, each with its own secondary instrument. 5.11. To record the main values of flow and pressure, single-point secondary devices with continuous recording are usually used (with a recommended tape pulling speed of 600 mm/h). Continuous recording is necessary due to the high speed of hydrodynamic processes, especially in case of instability. If there is a large number of the same type of hydraulic sensors in the circuit (for example, for measuring velocities in panels and coils), some of them can be transferred to multi-point secondary instruments indicated in Table. 2 (for 6 or 12 points with a cycle of no more than 4 s). 5.12. The experimental control panel is mounted near the main control room (preferably), or in the boiler shop room (at the service level if there is good communication with the main control room). The panel is equipped with electrical power, lighting, and locks. 5.13. Materials: 5.13.1. The quantity and range of materials required for the installation of connecting electrical and pipe wiring, as well as electrical and thermal insulating materials, are determined in the test work program or in the order specification, depending on the steam or heat output of the boiler, its design and the volume of measurements. 5.13.2. The primary switching of temperature measuring instruments to prefabricated boxes (SC) is carried out: from submersible thermocouples and temperature inserts with a compensation wire (copper-constantan for XA thermocouples, chromel-copel for XK thermocouples); from surface thermocouples with a thermocouple wire. Secondary switching from the SC to the experimental control panel is performed with a multi-core cable (preferably a compensation cable, if this is not available - copper or aluminum). In the latter case, to compensate the temperature of the free end of the measuring thermocouples, a so-called compensation thermocouple is inserted from the SC to the device. 5.13.3. Switching of flow and pressure signals from the sampling point to the sensor is carried out by connecting tubes (made of steel 20 or 12Х1МФ) with shut-off valves d y
10 mm for the corresponding pressure. The electrical connection between the sensor and the panel is made with a four-core cable (in case of danger of interference, shielded). 6. TEST CONDITIONS
6.1. Tests are carried out in stationary boiler modes, in transient modes (during mode disturbances, decrease and increase in load), and also, if necessary, in firing modes. 6.2. When carrying out tests in stationary modes, the values indicated in the table must be maintained. 3 maximum deviations from the average operational values of boiler operating parameters, which are monitored using verified standard instruments. Table 3|
Name |
Maximum deviations, % |
Steam boilers steam capacity, t/h |
Hot water boilers |
Steam capacity | Feed water consumption | Pressure | Temperature of superheated steam (primary and intermediate) | Water temperature (at the inlet and outlet of the boiler) |
7. PREPARATION FOR TESTS
7.1. The scope of work to prepare for testing includes: familiarization with technical documentation for the boiler and power unit, equipment condition, operating modes; drawing up and approval of a test program; development of an experimental control scheme and technical documentation for it; technical supervision of the installation of an experimental control scheme; adjustment of the scheme experimental control and its implementation. 7.2. The technical documentation that requires familiarization includes, first of all: drawings of the boiler and its elements; diagrams of steam-water and gas-air paths, instrumentation and automation; boiler calculations: thermal, hydraulic, thermomechanical, wall temperature, hydraulic characteristics (if any); boiler operating instructions, operating map; documentation on damage to pipes, etc. On-site familiarization with the equipment of the boiler and dust preparation system, with the power unit as a whole, and with standard instrumentation is carried out. The operational features of the equipment to be tested are identified. 7.3. A test program is drawn up, which must indicate the purpose, conditions and organization of the experiments, requirements for the condition of the boiler, the necessary parameters of the boiler operation, the number and main characteristics of the experiments, their duration, and calendar dates. The non-standardized measuring instruments used are indicated. The program is coordinated with the heads of the relevant departments of the thermal power plant (KGC, Central Research Institute, TsTAI) and approved by the chief engineer of the thermal power plant or REU. The procedure for the development, coordination and approval of the test program must comply with the “Regulations on the procedure for the development, coordination and approval of test programs at thermal, hydraulic and nuclear power plants , in energy systems, thermal and electrical networks", approved by the USSR Ministry of Energy on August 14, 1986. 7.4. The contents of the experimental control scheme are given in Section. 4. In some cases, with a large volume of tests, a technical specification is drawn up for a draft experimental control scheme, according to which a specialized organization or department develops the scheme. If the volume is small, the diagram is drawn up directly by the team conducting the tests. 7.5. Based on the experimental control scheme, documentation on preparatory work for testing is compiled and transferred to the customer: a list of preparatory work (in which it is advisable to indicate the scope of installation work performed directly on the boiler); specifications for the necessary devices and materials supplied by the customer; sketches of devices requiring manufacturing ( temperature inserts, bosses, shield panels, etc. A specification for instruments and materials supplied by Soyuztekhenergo is also drawn up. Appendix 2 provides sample examples of this documentation. 7.6. Installation supervision: 7.6.1. Before installation begins, the locations for installing measuring devices are marked, as well as the locations for the monitoring system, switchboard, and sensor stands are selected. The marking must be treated with special attention, as an operation that determines the quality of subsequent measurements. When installing test equipment, it is necessary to check the correct installation of the measuring devices and compliance with the drawings. 7.6.2. Welding of surface thermocouple bosses is carried out under the direct supervision of team representatives. The main thing is to prevent the wire from burning out (welding with 2-3 mm electrodes, minimum current), and in case of a burnout, restore it again. It is recommended to check the presence of the chain immediately after welding. 7.6.3. The thermocouple and compensation wires are laid to the SC in protective pipes. Open laying with a harness is allowed in some cases for a short time, but is not recommended. Laying should be done with a single wire, avoiding intermediate connections. Particular attention should be paid to possible places where the insulation of wires is damaged (kinks, turns, fastenings, entrances to protective pipes, etc.), protecting them with additional reinforced insulation. To eliminate possible EMF interference, compensation wires and cables should not intersect with power cable routes. 7.6.4. Pressure tubes are installed on straight sections of pipes, away from bends and manifolds. The straight section of flow stabilization in front of the tube should be (20 ¸ 30) D (D - internal diameter of the pipe), but not less than 5 D. Pressure tube immersion is 1/2 or 1/3 D . The tube must be welded with signal-perceiving holes strictly along the center line of the pipe; select fittings are located horizontally. Main valves must be accessible for maintenance. 7.6.5. The laying of connecting lines for flow and pressure measurements must meet the requirements of RD 50-213-80. When laying connecting pipes, one-sided slope or horizontal lines must be strictly observed; Do not allow connecting pipes to pass in places with high temperatures to avoid boiling or heating of still water in them. 7.6.6. Sensors for measuring flow rates and differential pressures are installed below (or at the level of) the measuring devices, usually at the zero mark and at the service mark. The sensors are mounted on group stands. For normal maintenance, devices are provided for purging the sensors (two shut-off valves are installed on each purge line to avoid leaks). The complete set for one sensor consists of 9 shut-off valves (main valves, in front of the sensor, purge valves and one equalizing valve). 7.6.7. Before installing the sensors on the stand, they should be carefully checked by the metrological service of the thermal power plant and calibrated. After installation on the stands, it is necessary to check the position of the “zeros” and the maximum values of the differences. For sensors designed to measure water flow rates in panels and coils, it is advisable to shift the “zero” on the scale of the secondary device by 10-20% to the right (in case zero or negative values in non-stationary modes). In some special cases, when flow movement in both directions is possible, the “zero” of the device is set to 50%, i.e. to the middle of the scale (for example, flow reversal, strong pulsation, hydrodynamic jumper tests, etc.). When the zero is shifted, the device is used as an indicator. 7.7. Upon completion of the preparatory installation work, the experimental control circuit is adjusted (switching continuity, crimping and trial activation of sensors, activation and debugging of secondary devices, identification and elimination of defects). 7.8. Before testing, the readiness of the boiler and its elements for testing must be checked (gas tightness, internal and external contamination of heating surfaces, density and serviceability of fittings, etc.). Particular attention is paid to standard instrumentation: the serviceability of the measuring instruments necessary for testing, the correctness of their readings, the presence of valid verification marks (for water meters and other devices), the compliance of experimental and standard instruments. The power plant is provided with a list of works to eliminate equipment and KI1 deficiencies that impede testing. The condition of the boiler must meet the requirements specified in the test program.8. TESTING
8.1. Work program of experiments: 8.1.1. Before the start of testing, on the basis of the approved test program, working experimental programs are drawn up and agreed with the management of the thermal power plant. The work program is drawn up for a single experiment or a series of experiments. It contains instructions for organizing the experiment, the state of the equipment involved in the experiment, the values of the main parameters and the permissible limits of their deviations, and a description of the sequence of operations performed. 8.1.2. The work program is approved by the chief engineer of the thermal power plant and is mandatory for personnel. 8.1.3. For the duration of the experiment, a responsible representative from the TPP must be allocated, who will provide operational management of the experiment. The test manager from Soyuztechenergo provides technical guidance. The watch personnel performs all their actions during the experiment according to the instructions (or with the knowledge) of the test manager, transmitted through the responsible representative of the thermal power plant. Appendix 3 provides an approximate work program for the experiments. 8.2. During the entire period of the experiment, compliance with the work program of the following values must be ensured: excess air; shares of flue gas recirculation; fuel consumption; feed water flow and temperature; medium pressure behind the boiler; steam consumption (only for steam boiler); temperature of fresh steam (or water) behind the boiler; combustion mode; operating mode of the dust preparation system. 8.3. If the boiler operating parameters do not comply with the requirements established in section. 6 and in the work program, the experiment stops. The experiment also ends in the event of an emergency at the power unit (or power plant). In case of reaching the limit values of the temperature of the medium and metal specified in the program, or the cessation (or sharp decrease) of the medium flow in individual elements of the boiler, or the appearance of other violations of hydrodynamics according to experimental control devices, the boiler is transferred to a mode easier for the equipment (previously entered disturbances or necessary decisions are made). If the violations do not pose an immediate danger, the experiment can continue without further tightening the regime being tested. 8.4. Tests begin with preliminary experiments. During preliminary experiments, familiarization with the operation of the equipment and the features of operating modes is carried out, final debugging of the measurement scheme, development of the organizational routine in the team and relationships with the watch personnel. 8.5. Stationary modes: 8. 5.1. Tests in stationary modes include experiments: at the rated load of the boiler; two or three intermediate loads (usually at loads of 70 and 50% as corresponding to factory calculations, as well as at the load prevailing under operating conditions); minimum load (established in operation or agreed upon for testing). For steam boilers, experiments are also carried out with a reduced temperature of the feed water (with the HPH turned off). For hot water boilers, experiments are also carried out: with different inlet water temperatures; with minimal outlet pressure; with the minimum permissible water flow. The static characteristics (dependence on the boiler load) of temperatures and pressures along the path are determined; indicators of hydraulic stability of the tested circuits in stationary modes; permissible range of boiler loads according to these indicators. 8.5.2. In stationary experiments, the regime according to the operational regime map is taken as a basis. The influence of the main operating factors is also checked (excess air, DRG loading, various combinations of operating burners or mills, fuel oil illumination, feed water temperature, boiler slagging, etc.). 8.5.3. On boilers operating on two types of fuel, experiments are carried out on both types (on reserve fuel and on a mixture of fuels, a reduced volume is allowed). On dust and gas boilers, experiments on natural gas to determine whether the screens are dirty should be carried out after a sufficiently long continuous campaign on gas. If necessary, experiments on slag fuels are carried out at the beginning and at the end of campaigns, on a “clean” and on a slagged boiler. 8.5.4. For SKD boilers operating at sliding pressure, hydraulic stability tests should be carried out taking into account the guidelines for testing once-through boilers in unloading modes at sliding pressure of the medium. 8.5.5. At a given boiler load, in order to obtain more reliable experimental materials, two duplicate experiments should be carried out, and not on the same day (preferably with a time gap). If necessary, additional control experiments are carried out. 8.5.6. Tests in stationary conditions must precede experiments with disturbances. 8.6. Transitional modes: 8.6.1. The most unfavorable in terms of hydraulic stability of boiler circuits are, as a rule, non-stationary conditions associated with regime disturbances and certain deviations of parameters from normal (average) conditions. In experiments in transient modes, the hydraulic stability of the tested circuits is determined in experimental conditions close to emergency ones, when the water-fuel ratio is unbalanced and when there are thermal imbalances. The maximum reduction in flow rates and temperature increases in the circuit elements, the discrepancy between individual elements, as well as the nature of the restoration of the original values after the disturbance is removed are monitored. 8.6.2. For steam boilers, the following mode disturbances are checked: a sharp increase in fuel consumption; a sharp decrease in feed water consumption; turning off individual burners while maintaining the total fuel consumption (the effect of thermal distortion across the width and depth of the furnace); turning off (or reducing the load) of the DRG; reducing the pressure of the medium, as well as other actions based on local circumstances (turning on blowers, switching to another fuel, etc.). Depending on the circuit diagram, sometimes it may also be necessary to check the combination of unbalance with skew (for example, water discharge when the burners are turned off). For hot water boilers, mode disturbances are checked a sharp decrease in feed water consumption and a decrease in medium pressure, etc. 8.6.3. The value and duration of disturbances are not standardized and are established on the basis of existing experience and actual operating conditions, depending on the design of the boiler, its dynamic characteristics, type of fuel, etc. Thus, for a gas-oil boiler of a 300 MW monoblock, we can recommend disturbances for water and fuel with a value of approximately 15 % and lasting 10 minutes (i.e., according to existing experience, almost until the parameters along the path stabilize). With large disturbances (20-30%), under the condition of maintaining the superheat temperature, the duration is usually less than 3-5 minutes without stabilization of parameters, which does not give confidence in identifying all the features of the hydrodynamics of the circuit. Disturbances of less than 15% have a relatively weak effect on the steam-water path. 8.6.4. Disturbances can be made along both or only one controlled flow of the steam-water path (or one side of the boiler) for which the tests are performed. 8.6.5. Before applying disturbances, the boiler must operate in a stationary mode for at least 0.5-1.0 hours until the parameters stabilize. 8.6.6. Experiments with regime disturbances are carried out at two or three boiler loads (including the minimum). Usually they are combined with experiments at the required load in a stationary mode and are carried out at the end of it. 8.7. If necessary (for example, a new kindling technology, damage during startup modes, the results of preliminary calculations causing concern, etc.), the hydraulic stability of the tested circuit is checked in the boiler firing modes. Kindling is carried out in accordance with the operating instructions and work program. 8.8. During the experiment, continuous monitoring of the operation of the boiler and its elements is carried out using standard and experimental control devices. It is necessary to constantly monitor experimental control measurements and promptly detect certain violations of hydrodynamics. Detection of hydrodynamic disturbances is the main task of testing. 8.9. An operational log is kept recording the progress of the experiment, operations performed by the watch personnel, main indicators of the regime and disturbances. Regular entries are made in observation logs of boiler parameters using standard instruments. The recording frequency is 10-15 minutes in stationary modes, 2 minutes during disturbances. Excess air is monitored (using oxygen meters or Orsa devices). It is necessary to monitor the combustion mode by inspecting the firebox. 8.10. Careful supervision is carried out over the serviceability of experimental control devices, including: the “zero” position, the position and pulling of the tape, the clarity of the readings on the tape, the correctness of the readings of instruments and individual points. Malfunctions must be corrected immediately. The correspondence of the readings of experimental and standard instruments according to similar parameters is verified*. Before each experiment, the flow and pressure sensors are registered and zeroed. At the end of the experiment, the registration of “zeros” is repeated. * The difference in readings should not exceed , where And 1 and And 2 - instrument accuracy classes. 8.11. Regularly at the beginning, end and throughout the experiment, to synchronize the instrument readings, a simultaneous time stamp is made on all tapes. The mark is made manually or with a large number of devices using a special electrical time marking circuit (simultaneous short-circuiting of the device circuits). 8.12. It is recommended, if possible, to subject the resulting experimental material to express processing immediately after the experiments. A preliminary analysis of the results of previously conducted experiments allows for more targeted subsequent experiments with timely adjustment of the test program if necessary. 8.13. During the testing period, in addition to planned experiments, observations of the operating conditions of the boiler are carried out using standard and experimental control devices. The purpose of the observations is to obtain confirmation of the representativeness and completeness of the experimental modes, data on the stability or instability of boiler parameters over time (which is especially important for pulverized coal boilers), as well as to obtain current information on the status of standard control measurements in preparation for the next experiments. The observation results are used as auxiliary material.9. PROCESSING OF TEST RESULTS
9.1. Test results are processed using the following formulas
G el
= (wr)el × F el; D i = iout - iinput ; 
h T = rq × rr × hk,Where F- internal cross-section of the pipeline, m 2 ; t us - saturation temperature by medium pressure at the outlet of the circuit, °C; a- flow coefficient of the measuring tube; D R measurement - pressure drop across the measuring tube, kgf/m2; v- specific volume of the medium, m 3 /kg; F el- internal cross-section of the element, m 2 ; i in,i out- enthalpy of the medium at the inlet and outlet of the circuit, kJ/kg (kcal/kg), taken from thermodynamic tables, i =
f(t,P),
pressure is taken at the inlet and outlet of the circuit; hk- the coefficient of structural non-identity of an element (individual pipe) is taken from design data according to [1]. For explanations of the remaining letter designations, see paragraphs. 1.1.7 and 1.1.8.9.2. Errors in determining indicators based on measurement results are determined as follows: d (wr) = d (G); D ( tinput) = D ( t); D ( tout) = D ( t); D ( tel) = D ( t); d(D R k)
= d(D R).Absolute error D( t us)
is found from thermodynamic tables and is equal to half the unit digit of the last significant digit. The permissible absolute error in temperature measurement is determined by the formula where D TP- permissible error of thermocouples; D hp - communication line error caused by deviation of the thermo-EMF of the extension wires; D etc- basic error of the device; D¶ i- additional instrument error from i th influencing environmental factor; p pr- the number of factors influencing the device. The permissible relative error in measuring flow rate, differential pressure and pressure is determined by the formulas: 
Where dsu -
permissible relative error of the restriction device; d ¶
- permissible relative error of the sensor; detc
- basic relative error of the device; d ¶ i ,
detci
- additional relative errors of the sensor and device from i th external influencing factor; P ¶ -
number of influencing factors on the sensor. 9.3. Before the start of processing, the time intervals of the experiments are specified and time markings are made on the chart tapes of the recorders (for stationary modes - at intervals of 5-10 minutes, for modes with disturbances - after 1 minute or every clear). The timing of the tapes of all devices is checked. Readings from the tapes are taken using special scales, which are calibrated according to standard scales or according to individual calibrations of instruments and sensors. Unrepresentative measurement results are excluded from processing. 9.4. The results of measurements in stationary modes are averaged over time during the experiment: boiler parameters according to entries in observation logs, other indicators according to recorder tapes according to the markings. Particular attention is required to processing the results of measurements of temperatures and pressures of the medium along the steam-water path, since enthalpy is determined from them and enthalpy increments in heating surfaces are calculated, which is the basis of a large part of the processing. The possibility of significant errors in determining enthalpy during SCD in the zone of high heat capacities (at subcritical pressure in the evaporation part) should be taken into account. The pressure at intermediate points in the duct is determined by interpolation, taking into account direct measurements and hydraulic calculations of the boiler. The average processing results are entered into tables and presented in the form of graphs (distribution of temperatures and enthalpies of the medium along the path, temperature and hydraulic measurements, dependence of the thermal and hydraulic performance of the circuit on the boiler load and on operating factors, etc.). 9.5. The task of testing in transient modes is to determine deviations of flow rates and temperatures in circuit elements from the initial stationary values (in terms of magnitude and rate of change). In view of this, the processing results are not averaged and are presented in the form of graphs depending on time. It is advisable to display areas with stability violations on separate graphs with an increased time scale or provide photocopies of the tapes. Kindling modes are also processed in the form of time graphs. 9.6. When processing hydraulic measurements, individual scales are used that correspond to the calibration of the sensor. The counting is made from the “zeros” marked on the tape during the experiments. For stationary modes when measuring flow, the pressure drop readings on the measuring device taken from the tape are recalculated into flow or mass velocity values. Recalculation is carried out using the formulas given in clause 9.1, or using auxiliary dependencies ( wr),
G from D R measurement, constructed on the basis of the specified formulas (for the operating range of temperatures and pressures of the medium). For transient modes when constructing a time graph, it is allowed not to recalculate the flow measurement in the circuit elements and to build the resulting graph in D values R measurement(showing approximate flow rates using the second scale on the graph). 9.7. The measured pressure values are corrected for the height of the water column in the connecting line (from the sampling point to the sensor); on the measured pressure difference - correction for the difference in height of the water column between the sampling points. 9.8. The most important part of processing test results is the comparison, analysis and interpretation of the obtained materials, assessment of their reliability and sufficiency. Preliminary analysis is carried out at intermediate stages of processing, which allows you to make the necessary adjustments along the way. In some more complex cases (for example, when results are obtained that differ from those expected, to assess the limits of stability outside the experimental data, etc.), it is advisable to perform additional calculations of hydraulic stability taking into account the experimental material. 10. PREPARATION OF A TECHNICAL REPORT
10.1. Based on the test results, a technical report is drawn up, which is approved by the chief engineer of the enterprise or his deputy. The report should contain test materials, analysis of materials and conclusions on the work with an assessment of the hydraulic stability of the boiler, conditions and limits of stability, as well as, if necessary, recommendations for increasing stability. The report must be prepared in accordance with STP 7010000302-82 (or GOST 7.32-81). 10.2. The report consists of the following sections: “Abstract”, “Introduction”, “Brief description of the boiler and the tested circuit”, “Test methods”, “Test results and their analysis”, “Conclusions and recommendations”. The introduction formulates the goals and objectives of the tests, the fundamental approach to their implementation and the scope of work are determined. The description of the boiler must include design characteristics, equipment, and the necessary data from factory calculations. The section “Test Methodology” provides information on the experimental control scheme, measurement technique and test procedure. The section “Test Results” and their analysis" covers the operating conditions of the boiler during the testing period, provides detailed results of measurements and their processing, as well as an assessment of the measurement error; an analysis of the results is given, the obtained indicators of hydraulic stability are considered, compared with existing calculations, the results are compared with known results from other tests of similar equipment, stability assessments and proposed recommendations are substantiated. Conclusions should contain an assessment of hydraulic stability (for individual indicators and in general) depending on boiler load, other operating factors and from the influence of non-stationary processes. If insufficient stability is identified, recommendations are given to improve operational reliability (operational and reconstructive). 10.3. Graphic material includes: drawings (or sketches) of the boiler and its components, a hydraulic diagram of the circuit under test, a measurement diagram (with the necessary components), drawings of non-standard measuring devices, graphs of the results of calculations, graphs of measurement results (primary material and generalizing dependencies), sketches of proposals on reconstruction (if any). The graphic material must be sufficiently complete and convincing so that the reader (customer) can get a clear understanding of all existing aspects of the tests carried out and the validity of the conclusions and recommendations made. 10.4. The report also provides a list of references and a list of illustrations. The appendix to the report includes summary tables of test data and calculations and copies of the necessary documents (acts, protocols).11. SAFETY REQUIREMENTS
Persons participating in testing must know and comply with the requirements set out in [3] and have an entry in the knowledge test certificate.Annex 1
DESIGN OF PRESSURE PIPES
When choosing a particular design of measuring pressure tubes (Pitot tubes), one should be guided by the required pressure drop, the flow area of the pipes, take into account the complexity of manufacturing a particular tube design, as well as the ease of their installation. The designs of pressure tubes for measuring circulation and water velocities are shown in Fig. . 3. TsKTI rod tube (see Fig. 3,a) is usually installed at a depth of 1/3 D, which is significant for small-diameter pipes. In Fig. Figure 3b shows the design of a cylindrical VTI tube. For screen pipes with an internal diameter of 50-70 mm, the diameter of the measuring tube is taken to be 8-10 mm, they are installed to a depth of 1/2 of the internal diameter of the pipe. The disadvantages of cylindrical tubes compared to rod ones include their greater cluttering of the internal cross-section, and the advantages are their simpler manufacture and lower flow coefficient, which leads to an increase in the pressure drop of the sensor at the same water flow. Along with the above designs of pressure tubes for measurement cylindrical through tubes are also used in circuits (see Fig. 3, c), which are easy to manufacture - only turning and drilling of channels. The flow coefficient of these tubes is the same as that of cylindrical VTI tubes. The specified measuring tube can be made of a simplified design - from two pieces of small diameter pipes (see Fig. 3d). Parts of the tubes are welded in the middle with a partition installed between them, so that there is no communication between the left and right cavities of the tube. Pressure signal sampling holes are drilled near the partition as close to each other as possible. After welding the tubes, the welding site should be thoroughly cleaned. To weld a tube into a screen or bypass pipe, it is welded to the fittings. To correctly install measuring tubes of any design along the water flow, marks should be made on the outer part of the end of the cylinder or fittings. In Fig. 4a shows the results of calibration of rod tubes with a length of the measuring part equal to 1/2, 1/3, 1/6 D(D- internal diameter of the pipe). As the length of the measuring part decreases, the value of the tube flow coefficient increases. For pipe with h = 1/6D the flow coefficient approaches unity. As the internal diameter of the pipe increases, the flow coefficient decreases for all lengths of the active part of the meter. From Fig. 4a it can be seen that the lowest flow coefficient, and therefore the highest pressure drop, have tubes with a measuring part length equal to 1/2 D. When using them, the influence of the internal diameter of the pipeline is significantly reduced. In Fig. 4, b the results of calibration of VTI tubes with a diameter of 10 mm with the measuring part set to 1/2 are presented D. Dependence of flow coefficient a the ratio of the diameter of the measuring tube to the internal diameter of the pipe in which it is installed is given in Fig. 4,c. The given flow coefficients are valid when measuring tubes are installed in screen pipes, i.e. for numbers Re, located at the level of 10 3, and acquire constant values for the TsKTI tubes at numbers Re³ (35 ¸40) ×10 3, and for VTI tubes at Re³ 20 ×10 3. In Fig. 4d shows the flow coefficient for a through cylindrical tube with a diameter of 20 mm depending on the length of the stabilizing section L pipes with an internal diameter of 145 mm. In Fig. 4, d shows the dependence of the flow coefficient and correction factor on the ratio of the diameters of the measuring tube and the pipe in which it is installed. The actual flow coefficient in this case will be: a f= a × TO Where TO - coefficient that takes into account other factors. Correct installation of pressure tubes increases the accuracy of determining velocities. The holes in the tube that receive the pressure signal must be located strictly along the axis of the pipe in which it is installed. Possible distortions in the tube readings if it is not installed accurately, obtained on the stand, are shown in Fig. 4f. Comparison of pressure tubes designed by TsKTI and VTI with an active length of the measuring part equal to 1/2 D shows that the pressure difference created at the same flow rate for VTI tubes for screen pipes with an internal diameter of 50 and 76 mm, respectively, is 1.3 and 1.2 times greater than for CNTI tubes. This ensures greater measurement accuracy, especially at low water velocities. Therefore, when the obstruction of the internal section of the pipe by the measuring tube is not of decisive importance (for pipelines of relatively large diameter), then VTI tubes should be used to measure water velocities. TsKTI tubes are most often used on coils of small internal diameter (up to 20 mm). Measuring water velocities less than 0.3 m/s, even with VTI tubes, is not recommended, since in this case the pressure drop is less than 70-90 Pa (7 -9 kgf/m 2), which is less than the lower guaranteed measurement limit for sensors used in flow measurement.Appendix 2
PREPARATORY WORK FOR TESTING THE SCREENS OF THE TGMP-314 BOILER OF THE KOstroma GRES
|
Name |
Quantity, pcs. |
Manufacturing of temperature inserts | Insertion of temperature inserts into the NRF and SRF | Opening of insulation on collectors and pipelines (NRCh, SRCh, VRC) |
25 plots |
Installation and welding of surface thermocouples | Switching thermocouples and inserts to junction boxes (JB) | Installation SK-24 | Laying compensation cable KMTB-14 | Installation of pressure pipes (with drilling in supply pipes and NRF coils) | Installation for pressure signal selection | Installation for selecting signals for ignition feedwater flow (from a standard diaphragm) | Laying connecting (impulse) pipes | Installation of flow sensors | Manufacturing and installation of a panel for 20 devices | Installation of secondary devices (KSP, KSU, KSD) | Preparing the work area | Technical inspection (audit) of standard measurement systems for the steam-water path | Installation of sewn lighting. |
|
Name |
Quantity, pcs. |
Differential pressure sensor DM, 0.4 kgf/cm 2 (at 400 kg/cm 2) | Pressure sensor DER 0-400 kgf/cm 2 | Differential pressure sensor DME, 0-250 kgf/cm 2 (at 400 kgf/cm 2) | Single-point KSD device | KSU single-point device | Device KSP-4, 0-600°, HA, 12-point | Compensation wire MK | XA thermoelectrode wire | Fiberglass | Silica tape (glass) | Insulation tape | Chart tape for KSP, 0-600°, HA | Chart tape for KSU (KSD), 0-100%, | Flat batteries | Round batteries |
Appendix 3
I affirm:Chief Engineer of State District Power Plant
WORK PROGRAM FOR CONDUCTING EXPERIMENTAL TESTS OF HYDRAULIC STABILITY OF NRF AND SRCH-1 OF BOILER No. 1 (with HPH)
1. Experiment 1. Set the following mode: power unit load - 290-300 MW, fuel - dust (without backlighting with fuel oil), excess air - 1.2 (3-3.5% oxygen), feed water temperature - 260°C ,in the operation of the 2nd and 3rd injections (30-40 t/h per flow). The remaining parameters are maintained in accordance with the regime map and the current instructions. During the experiment, if possible, do not make any changes in the regime. All operating automation is in operation. Duration of experiment - 2 hours. Experience 1 a. The influence of the water-fuel imbalance on the stability of hydrodynamics is checked. Set the same mode as in experiment 1. Turn off the fuel regulator. Sharply reduce the feed water consumption along stream “A” by 80 t/h without changing the fuel consumption. After 10 minutes, in agreement with the representative of Soyuztechenergo, restore the original water flow. During the experiment, temperature control along the boiler path should be carried out by injection. The permissible limits of short-term deviation of the fresh steam temperature are 525-560°C (no more than 3 minutes), the temperature of the medium along the boiler path is ±50°C from the calculated ones (no more than 5 minutes, see paragraph 4 of this appendix). Duration of the experiment is 1 Part 2. Experiment 2. Set the following mode: power unit load - 250-260 MW, fuel - dust (without backlighting with fuel oil), excess air - 1.2-1.25 (3.5-4% oxygen), temperature feed water - 240-245°C, in operation of the 2nd and 3rd injections (25-30 t/h per flow). The remaining parameters are maintained in accordance with the regime map and the current instructions. During the experiment, if possible, do not make any changes in the regime. All operating automation is in operation. Duration of experiment - 2 hours. Experiment 2a. The effect of misalignment on the burners is checked. Set the same mode as in experiment 2, but on 13 dust feeders (dust feeders No. 9, 10, 11 are turned off). Duration of the experiment is 1.5 hours. Experiment 2b. The influence of the water-fuel imbalance is checked. Set the same mode as in experiment 2a. Turn off the fuel regulator. Sharply reduce the feed water flow along stream “A” by 70 t/h without changing fuel consumption. After 10 minutes, in agreement with the representative of Soyuztekhenergo, restore the initial water flow. During the experiment, temperature control along the boiler path should be carried out by injection. Permissible limits of short-term deviation of fresh steam temperature 525-560°C (no more than 3 minutes), medium temperature along the boiler path ±50°C from the calculated one (no more than 5 minutes, see clause 4 of this appendix). Duration of the experiment - 1 hour .3. Experiment 3. Set the following mode: power unit load 225-230 MW, fuel - dust (at least 13 dust feeders in operation, without fuel oil illumination), excess air - 1.25 (4-4.5% oxygen), feed water temperature - 235-240°C, in operation of the 2nd and 3rd injections (20-25 t/h per flow). The remaining parameters are maintained in accordance with the regime map and the current instructions. During the experiment, if possible, do not make any changes in the regime. All operating automation is in operation. Duration of experiment - 2 hours. Experiment 3a. The influence of the water-fuel imbalance and the inclusion of burners is checked. Set the same mode as in experiment 3. Increase the excess air to 1.4 (6-6.5% oxygen). Disable the fuel regulator. Dramatically increase fuel consumption by increasing the rotation speed of the dust feeders by 200-250 rpm without changing the water flow through the streams. After 10 minutes, in agreement with the representative of Soyuztekhenergo, restore the original speed. Stabilize the regime. Sharply increase fuel consumption by simultaneously turning on two dust feeders in the left half-furnace without changing the water flow along the streams. After 10 minutes, in agreement with the representative of Soyuztekhenergo, restore the original fuel consumption. During the experiment, temperature control along the boiler path should be carried out by injection. The permissible limits of short-term deviation of the overheating temperature are 525-560°C (no more than 3 minutes), the temperature of the medium along the boiler path is ±50°C from the calculated ones (no more than 5 minutes, see paragraph 4 of this appendix). Duration of the experiment is 2 hours. Notes: 1. KTC appoints a responsible representative for each experiment. 2. All operational actions during the experiment are carried out by the watch personnel on the instructions (or with the knowledge and agreement) of the responsible representative of Soyuztechenergo. 3. In the event of emergency situations, the experiment is terminated and the watch personnel act in accordance with the relevant instructions. 4. Limit short-term ambient temperatures along the boiler path, ° C: for SRCh-P 470 to VZ 500 behind screens - I 530 behind screens - II 570. Signature: _________________________________________________ (test manager from Soyuztekhenergo) Agreed by: _____________________________________________ (heads of GRES workshops)
List of used literature
1. Hydraulic calculation of boiler units (standard method). M.: "Energy", 1978, - 255 p. 2. Kemelman D.N., Eskin N.B., Davidov A.A. Setting up boiler units (handbook). M.: "Energy", 1976. 342 p. 3. Safety rules for the operation of thermal mechanical equipment of power plants and heating networks. M.: Energoatomizdat, 1985, 232 p.To check the strength of the structure and the quality of its manufacture, all elements of the boiler, and then the boiler assembly, are subjected to hydraulic tests with test pressure R etc. Hydraulic tests are carried out after completion of all welding work, when insulation and protective coatings are still missing. The strength and density of welded and rolling joints of elements is checked by test pressure R pr = 1.5 R r, but not less R p + 0.1 MPa ( Rр – operating pressure in the boiler).
Dimensions of elements tested under test pressure R p + 0.1 MPa, as well as elements tested at a test pressure higher than indicated above, must be subject to a test calculation for this pressure. In this case, stresses should not exceed 0.9 of the yield strength of the material σ t s, MPa.
After final assembly and installation of fittings, the boiler undergoes a final hydraulic pressure test R pr = 1.25 R r, but not less R p + 0.1 MPa.
During hydraulic tests, the boiler is filled with water and the operating water pressure is brought to the test pressure R with a special pump. Test results are determined by visual inspection of the boiler. And also by the rate of pressure drop.
The boiler is considered to have passed the test if the pressure in it does not drop and upon inspection no leaks, local bulges, visible changes in shape or residual deformations are detected. Sweating and the appearance of small droplets of water at the rolling joints are not considered a leak. However, the appearance of dew and tears welds not allowed.
Steam boilers, after installation on a ship, must be subjected to a steam test at operating pressure, which consists of putting the boiler into operational condition and testing it in operation at operating pressure.
The gas cavities of recovery boilers are tested with air at a pressure of 10 kPa. Gas ducts of auxiliary and combined PCs are not tested.
4. External inspection of boilers under steam.
External inspection of boilers complete with apparatus, equipment, service mechanisms and heat exchangers, systems and pipelines is carried out under steam at operating pressure and, if possible, combined with a check of the operation of ship mechanisms.
During the inspection, it is necessary to make sure that all water indicating devices are in good condition (water gauge glasses, test taps, remote water level indicators, etc.), as well as that the upper and lower blowing of the boiler is working properly.
The condition of the equipment, the proper operation of the drives, the absence of steam, water and fuel leaks in the seals, flanges and other connections must be checked.
Safety valves must be tested for operation. The valves must be adjusted to the following pressures:
valve opening pressure
R open ≤ 1.05 R slave for R slave ≤ 10 kgf/cm 2 ;
R open ≤ 1.03 R slave for R slave > 10 kgf/cm 2 ;
Maximum permissible pressure when the safety valve is in operation R max ≤ 1.1 R slave.
Superheater safety valves should be adjusted to operate somewhat ahead of the boiler valves.
Manual actuators for releasing safety valves must be tested in operation.
If the results of the external inspection and operational testing are positive, one of the boiler safety valves must be sealed by the inspector.
If checking the safety valves on recovery boilers while parked is not possible due to the need long work main engine or the impossibility of supplying steam from an auxiliary boiler operating on fuel, then the adjustment check and sealing of the safety valves can be carried out by the shipowner during the voyage with the execution of the corresponding report.
During the inspection, the operation of the automatic control systems of the boiler installation must be checked.
At the same time, you should make sure that the alarm, protection and blocking devices work flawlessly and are triggered in a timely manner, in particular when the water level in the boiler drops below the permissible level, when the air supply to the furnace is cut off, when the torch in the furnace is extinguished and in other cases provided for by the automation system.
You should also check the operation of the boiler installation when switching from automatic to manual control and vice versa.
If, during an external inspection, defects are discovered, the cause of which cannot be established by this inspection, the inspector may require an internal examination or hydraulic test.
TO category:
Maintenance and repair of boiler and steam machine
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Technical examination of boilers
Crane boilers as pressure vessels must meet the requirements of the Rules for the design, installation, maintenance and inspection of steam boilers, steam superheaters and water economizers.
According to these rules, each operated boiler is subjected to a technical examination by the Boiler Supervision Inspectorate within a specified period of time. The purpose of the inspection is to check the technical condition of the boiler, the proper operation of instruments and fixtures and the correct maintenance of the boiler.
The types and terms of technical inspections of the boiler are as follows: – external inspection - at least once a year; – internal inspection- at least once every three years; – hydraulic test - at least once every six years.
When hydraulic testing a boiler, its internal inspection is required. When the boiler cannot be stopped for technical inspection due to operating conditions set time, but in my own way technical condition its further operation does not cause concern; the inspection period can be extended by the Kotlonadzor inspection to three months.
Early hydraulic testing of the boiler is carried out by the Boiler Supervision Inspectorate in cases where: – the boiler was inactive for more than one year before being put into operation; – the boiler has been dismantled and moved to another tap or to another location; – more than 50% of the total number of screen and boiler pipes or 100% of steam superheating, economizer and smoke pipes; – more than 15% of the total number of connections of any boiler wall has been replaced; – at least part of the boiler wall sheet has been replaced or at least 15 adjacent rivets or at least 25% of all rivets in any seam have been re-riveted; – when repairing the boiler, welding of its parts under operating pressure was used (with the exception of tubular heating surfaces); – when repairing the boiler, bulges and dents on its main elements (fire tubes, firebox sheets, drums, etc.) were straightened out.
The Kotlonadzor inspector is given the right to inspect any type of boiler ahead of schedule if its condition requires such an inspection. The reasons that led to the early inspection of the boiler are recorded in the cord book.
An external inspection is carried out by a Boiler Supervision inspector while the boiler is operating. At the same time he checks external condition boiler and its fittings, knowledge of the rules by crane crews technical operation boiler
The boiler must be properly prepared for internal inspection. It is cooled, washed, cleaned of scale and soot, the grates are removed, the insulation is removed along the seams of the boiler and at the valve fittings in places of leaks.
During the inspection, they check the condition of the walls, connections, rivet and weld seams, the tightness of the pipes, look for cracks, bulges, corrosion of the boiler metal and other defects, and pay attention to the cleanliness of the boiler walls. Internal examination is usually performed at average and major renovation tap.
The boiler is subjected to hydraulic testing in order to check its strength, the density of pipes, rivet and welded joints. During testing, the boiler is filled with water, which is pumped under pressure with a pump. The pressure during testing should be for boilers operating at pressures above 5 kg/cm2 25% higher than the operating pressure, but not less than +3 kg/cm; for boilers whose operating pressure is less than 5 kg/cm2 - 50% more than the operating pressure, but not less than 2 kg/cm2. The boiler must be under test pressure for 5 minutes. The increase and decrease in pressure is carried out gradually. Pressure equal to the operating pressure is maintained for the entire time required to inspect the boiler.
The test pressure is measured with a control pressure gauge from the Kotlonadzor inspector. The boiler is recognized as having passed the hydraulic test if: – there are no signs of rupture; – no leak was noticed; in this case, the release of water through the rivet seams in the form of fine dust or drops (“tears”), as well as the release of water due to leaks in the fittings, is not considered a leak unless a decrease in the test pressure is observed; – no residual deformations were observed after the test.
When “tears” and sweating appear in welds the boiler is considered to have failed the test. Defective areas of such seams are cut out and welded again.
During the hydraulic test, an internal inspection of the boiler is also carried out.
The inspection results are recorded in the steam boiler book (YAKU form No. 1), sealed with a wax seal. In addition to this book, there is also a book on the operation of a steam boiler (YAC form No. 2).