The operating parameters of the steam turbine control system must satisfy Russian state standards and technical specifications for the supply of turbines.
The degree of uneven regulation of steam pressure in regulated extractions and back pressure must satisfy the consumer requirements agreed with the turbine manufacturer and prevent the safety valves (devices) from tripping.
All inspections and tests of the turbine overspeed control and protection system must be carried out in accordance with the instructions of the turbine manufacturers and current governing documents.
The safety circuit breaker must operate when the turbine rotor speed increases by 10 - 12% above the nominal value or to the value specified by the manufacturer.
When the safety circuit breaker is triggered, the following must close:
stop, control (stop-regulating) valves fresh steam and reheat steam;
stop (shut-off), control and check valves, as well as control diaphragms and steam extraction dampers;
shut-off valves on steam pipelines connecting with third-party sources of steam.
The turbine protection system against increased rotor speed (including all its elements) must be tested by increasing the rotation speed above the rated speed in the following cases:
a) after installation of the turbine;
b) after major repairs;
c) before testing the control system by load shedding with disconnection of the generator from the network;
d) during startup after disassembling the safety circuit breaker;
e) during startup after a long (more than 3 months) idle time of the turbine, if it is not possible to check the operation of the strikers of the safety circuit breaker and all protection circuits (with impact on the actuators) without increasing the rotation speed above the nominal one;
e) during startup after the turbine has been idle in reserve for more than 1 month. if it is not possible to check the operation of the strikers of the safety circuit breaker and all protection circuits (with impact on the executive bodies) without increasing the rotation speed above the nominal one;
g) during startup after disassembling the control system or its individual components;
h) during scheduled tests (at least once every 4 months).
In cases “g” and “h”, it is allowed to test the protection without increasing the rotation speed above the rated one (in the range specified by the turbine manufacturer), but with mandatory verification of the operation of all protection circuits.
Tests of turbine protection by increasing rotation speed must be carried out under the guidance of the workshop manager or his deputy.
The tightness of the live steam stop and control valves should be checked by testing each group separately.
The density criterion is the turbine rotor speed, which is set after the valves being tested are completely closed at full (nominal) or partial steam pressure in front of these valves. The permissible value of the rotation speed is determined by the manufacturer's instructions or current governing documents, and for turbines, the testing criteria for which are not specified in the manufacturer's instructions or current governing documents should not be higher than 50% of the nominal value at the nominal parameters in front of the valves being tested and the nominal exhaust pressure pair.
When all stop and control valves are closed simultaneously and the fresh steam and back pressure (vacuum) are at nominal parameters, passing steam through them should not cause rotation of the turbine rotor.
Checking the tightness of the valves should be carried out after installing the turbine, before testing the safety circuit breaker by increasing the rotation speed, before stopping the turbine in major renovation, at startup after it, but at least once a year. If signs of a decrease in valve density are detected during turbine operation, an extraordinary check of their density must be carried out.
Stop and control valves for fresh steam, stop (cut-off) and control valves (diaphragms) for steam extraction, shut-off valves on steam lines for communication with third-party sources of steam must be moved: to full speed - before starting the turbine and in cases stipulated by the manufacturer's instructions; for part of the stroke - every day during turbine operation.
When moving the valves to full stroke, the smoothness of their movement and seating must be checked.
The tightness of the check valves of regulated extractions and the operation of the safety valves of these extractions must be checked at least once a year and before testing the turbine for load shedding.
Check valves of regulated heating steam extractions, which are not connected to the extractions of other turbines, ROU and other steam sources, do not need to be tested for density unless there are special instructions from the manufacturer.
The seating of check valves of all extractions must be checked before each start-up and when stopping the turbine, and during normal operation periodically according to a schedule determined by the technical manager of the power plant, but at least once every 4 months.
If the check valve is faulty, operation of the turbine with appropriate steam extraction is not allowed.
Checking the closing time of stop (protective, shut-off) valves, as well as taking characteristics of the control system with the turbine stopped and when it is running idling must be done:
after installation of the turbine;
immediately before and after a major overhaul of the turbine or repair of the main components of the control or steam distribution system.
Tests of the turbine control system by instantaneous load shedding corresponding to the maximum steam flow must be performed: 
when accepting turbines into operation after installation;
after reconstruction that changes the dynamic characteristics of the turbine unit or the static and dynamic characteristics of the control system.
If deviations in the actual characteristics of regulation and protection from standard values are detected, valve closing time increases beyond those specified by the manufacturer or in local instructions, or their density deteriorates, the causes of these deviations must be identified and eliminated.
The operation of turbines with a power limiter put into operation is permitted as a temporary measure only under the conditions of the mechanical condition of the turbine installation with the permission of the technical manager of the power plant. In this case, the turbine load must be lower than the limiter setting by at least 5%.
Shut-off valves installed on the lines of the lubrication, regulation and sealing systems of the generator, the erroneous switching of which can lead to shutdown or damage to the equipment, must be sealed in the operating position.
Before starting up a turbine after a medium or major overhaul, the serviceability and readiness to turn on the main and auxiliary equipment, instrumentation, remote and automatic control devices, process protection devices, interlocks, information and operational communications must be checked. Any defects identified must be corrected.
Before starting a turbine from a cold state (after it has been in reserve for more than 3 days), the following must be checked: the serviceability and readiness for switching on of equipment and instrumentation, as well as the operability of remote and automatic controls, process protection devices, interlocks, information and operational communications; passing technological protection commands to all actuators; serviceability and readiness to turn on those facilities and equipment on which repair work was carried out during downtime. Any malfunctions identified must be eliminated before start-up.
The start-up of the turbine should be supervised by the workshop shift supervisor or senior machinist, and after a major or medium repair - by the workshop supervisor or his deputy.
Starting the turbine is not allowed in the following cases:
deviations of indicators of the thermal and mechanical conditions of the turbine from the permissible values regulated by the turbine manufacturer;
malfunction of at least one of the protections acting to stop the turbine;
the presence of defects in the control and steam distribution systems, which can lead to turbine acceleration;
malfunction of one of the oil lubrication pumps, regulation, generator seals or their automatic switching devices (AVR);
deviations in oil quality from the standards for operating oils or a drop in oil temperature below the limit set by the manufacturer;
deviations in fresh steam quality chemical composition from normal
Without turning on the turning device, supplying steam to the turbine seals, discharging hot water and steam into the condenser, and supplying steam to warm up the turbine are not allowed. The conditions for supplying steam to a turbine that does not have a shaft turning device are determined by local instructions. 
The discharge of the working medium from the boiler or steam lines into the condenser and the supply of steam to the turbine to start it must be carried out at steam pressures in the condenser specified in the instructions or other documents of the turbine manufacturers, but not higher than 0.6 (60 kPa).
When operating turbine units, the mean square values of the vibration velocity of the bearing supports should not be higher than 4.5 mm s -1.
If the standard vibration value is exceeded, measures must be taken to reduce it within no more than 30 days.
When vibration exceeds 7.1 mm s -1, it is not allowed to operate turbine units for more than 7 days, and when vibration is 11.2 mm s -1, the turbine must be turned off by protection or manually.
The turbine must be stopped immediately if, in steady state, there is a simultaneous sudden change in the vibration of the rotation frequency of two supports of one rotor, or adjacent supports, or two vibration components of one support by 1 mm s -1 or more from any initial level.
The turbine must be unloaded and stopped if, within 13 days, there is a smooth increase in any vibration component of one of the bearing supports by 2 mm·s -1.
Operation of the turbine unit during low-frequency vibration is unacceptable. If low-frequency vibration exceeding 1 mm·s -1 occurs, measures must be taken to eliminate it.
Temporarily, until equipped with the necessary equipment, vibration control based on the range of vibration displacement is allowed. In this case, long-term operation is allowed with a vibration range of up to 30 microns at a rotation speed of 3000 and up to 50 microns at a rotation speed of 1500; a change in vibration by 12 mm s -1 is equivalent to a change in the amplitude of vibrations by 1020 µm at a rotation speed of 3000 and 2040 µm at a rotation speed of 1500.
Vibration of turbine units with a power of 50 MW or more should be measured and recorded using stationary equipment for continuous vibration monitoring of bearing supports that meets state standards.
To monitor the condition of the turbine flow path and its contamination with salts, the steam pressure values in the control stages of the turbine should be checked at least once a month at close to the nominal steam flow rates through the controlled compartments.
The increase in pressure in the control stages compared to the nominal one at a given steam flow rate should be no more than 10%. In this case, the pressure should not exceed the limit values set by the manufacturer.
When the pressure limits in the control stages are reached due to salt deposits, the turbine flow path must be flushed or cleaned. The method of flushing or cleaning should be selected based on the composition and nature of the deposits and local conditions.
During operation, the efficiency of a turbine installation must be constantly monitored through a systematic analysis of indicators characterizing the operation of the equipment.
To identify the reasons for the decrease in the efficiency of a turbine installation and assess the effectiveness of repairs, operational (express) tests of the equipment must be carried out.
The turbine must be immediately stopped (disconnected) by personnel if the protection fails or is absent in the following cases: 
increasing the rotor rotation speed above the safety circuit breaker setting;
unacceptable axial shift of the rotor;
unacceptable change in the position of the rotors relative to the cylinders;
unacceptable decrease in oil pressure (fire-resistant liquid) in the lubrication system;
unacceptable drop in oil level in the oil tank;
an unacceptable increase in oil temperature at the drain from any bearing, generator shaft seal bearings, or any turbo unit thrust bearing block;
ignition of oil and hydrogen on a turbine unit;
an unacceptable decrease in the oil-hydrogen pressure difference in the turbogenerator shaft seal system;
an unacceptable decrease in the oil level in the damper tank of the oil supply system for the turbogenerator shaft seals;
turning off all oil pumps of the hydrogen cooling system of the turbogenerator (for non-injector oil supply schemes for seals);
shutdown of the turbogenerator due to internal damage;
unacceptable increase in pressure in the condenser;
unacceptable pressure drop at the last stage of turbines with back pressure;
sudden increase in vibration of the turbine unit;
the appearance of metallic sounds and unusual noises inside the turbine or turbogenerator;
the appearance of sparks or smoke from bearings and end seals of a turbine or turbogenerator;
unacceptable decrease in the temperature of fresh steam or steam after reheating;
the appearance of hydraulic shocks in the steam lines of fresh steam, reheating or in the turbine;
detection of a rupture or through crack in non-disconnectable sections of oil pipelines and pipelines of the steam-water path, steam distribution units;
stopping the flow of cooling water through the turbogenerator stator;
unacceptable reduction in cooling water consumption for gas coolers;
loss of voltage on remote and automatic control or at all instrumentation;
the appearance of a circular fire on the slip rings of the rotor of a turbogenerator, auxiliary generator or exciter manifold;
failure of the software and hardware complex of the automated process control system, leading to the impossibility of managing or monitoring all equipment of the turbine installation.
The need to break the vacuum when shutting down the turbine must be determined by local regulations in accordance with the manufacturer's instructions. 
The local instructions must provide clear instructions about unacceptable deviations in the values of controlled quantities for the unit.
The turbine must be unloaded and stopped within a period determined by the technical manager of the power plant (with notification of the power system dispatcher), in the following cases:
jamming of stop valves of fresh steam or steam after reheating;
jamming of control valves or breakage of their rods; jamming of rotary diaphragms or check valves;
malfunctions in the control system;
disruption of the normal operation of auxiliary equipment, circuits and communications of the installation, if eliminating the causes of the disruption is impossible without stopping the turbine;
increase in vibration of supports above 7.1 mm·s -1;
identifying malfunctions of technological protections acting to stop equipment;
detection of oil leaks from bearings, pipelines and fittings that create a fire hazard;
detection of fistulas in sections of steam-water pipelines that cannot be disconnected for repair;
deviations in the quality of fresh steam in terms of chemical composition from the norms;
detection of unacceptable concentrations of hydrogen in bearing housings, conductors, oil tank, as well as hydrogen leakage from the turbogenerator housing that exceeds the norm.
For each turbine, the duration of the rotor run-out must be determined during shutdown with normal exhaust steam pressure and during shutdown with vacuum failure. When changing this duration, the reasons for the deviation must be identified and eliminated. The duration of the run-down must be monitored during all shutdowns of the turbine unit.
When putting a turbine into reserve for a period of 7 days or more, measures must be taken to preserve the equipment of the turbine installation.
Thermal testing of steam turbines must be carried out.
From the standpoint of compliance with the operating characteristics of the PSU during their operation, the main attention is paid to constant and variable operating modes steam turbine.
Constant operation of a steam turbine. For modern powerful turbine units at thermal and nuclear power plants with a unit capacity from several hundred MW to 1000–1500 MW, which, as a rule, are operated in constant mode maximum load, indicators such as efficiency, reliability, durability and maintainability come first.
The profitability of vocational schools is characterized as a coefficient useful action(efficiency) of a turbine unit (TU), and specific gross heat consumption (i.e., excluding energy costs for the TU’s own needs). The efficiency indicators for district heating turbine units with controlled extractions for heating and hot water supply are: specific consumption steam in heating mode, specific heat consumption in condensation mode, specific heat consumption for electricity generation, etc. Gross specific heat consumption for condensing turbines high power is at the level of 7640–7725 kJ/(kWh); for thermal power plants – 10200 kJ/(kWh) and 11500 kJ/(kWh) for nuclear power plants. The specific gross heat consumption for district heating turbine units at a cooling water temperature of 20°C in condensation mode is about 8145–9080 kJ/(kWh), and the specific steam consumption in district heating mode is no more than 3.6–4.3 kg/( kWh).
Reliability and durability are characterized by a number of quantitative indicators, such as mean time between failures, full assigned service life, full assigned resource of elements, average term service between major overhauls, coefficient technical use, availability factor and others. The full designated service life of a power unit manufactured before 1991 is at least 30 years, equipment manufactured after 1991 is at least 40 years. The full assigned resource (park life) of the main elements operating at temperatures above 450°C is 220 thousand hours of operation. For high-power turbines, a mean time between failures of at least 5500 hours and a availability factor of at least 97% are established.
The variable operating mode of a steam turbine involves, first of all, a change in the steam flow through the flow part - towards a decrease from the nominal one. At the same time minimal losses with variable, i.e. “partial” steam flow is achieved with nozzle regulation, when the valves (valve) serving one specific group of nozzles are fully open. Heat differences change significantly only at the control and last stages of the flow part. The heat drops of the intermediate stages remain almost constant as the steam flow through the turbine decreases. The operating conditions of the intermediate stages and, consequently, the efficiency. all levels high pressure(except for the first stage), medium pressure and low pressure(except for the last stage) practically do not change.
The greater the lift of the valve serving any one group of nozzles, the smaller the increment in flow rate per “unit” of its lift. When h/d ≈ 0.28 is reached (where h is the linear displacement of the valve when it opens, and d is the valve diameter), the increment in steam flow through the valve practically stops. Therefore, to ensure a smooth loading process, it is planned to open the valve serving the next group of nozzles with some “overlap”, i.e. slightly earlier than the previous valve opens completely.
For the last stage of a low-pressure cylinder, a decrease in the relative volumetric flow rate of steam to a value below 0.4 GV 2 leads to the formation of vortices in the main flow both at the root of the working blades of the last stage and at their periphery, which is dangerous from the point of view of dynamic off-design stresses in these blades, which are already loaded to the limit.
Basics of steam turbine operation. The requirements for maneuverability and reliability of modern steam turbines during their operation are associated with general conditions operation of power systems, daily, annual schedules of energy consumption, the structure of generating capacities in power systems, their condition and technical capabilities. Currently, the electrical load schedules of power systems are characterized by great unevenness: sharp load peaks in the morning and evening hours, dips at night and on weekends, when it is necessary to ensure a rapid increase and decrease in loads. Maneuverability is understood as the ability of a power unit to change power during the day to cover the load schedule of the power system. Important in this regard are the periods of loading and unloading of the turbine unit, as well as starting from various thermal states (hot - after a preliminary downtime of less than 6–10 hours, cold - after a preliminary downtime of 10 to 70–90 hours, cold - after a preliminary downtime of more than 70–90 hours). Also take into account the number of stops and starts over the entire service life, the lower limit of the adjustment range, i.e. the lower limit of the load interval, when the power changes automatically without changing the composition of the auxiliary equipment, and the ability to work on the load of own needs after load shedding.
The reliability of the power unit operation largely depends on how protected the turbine itself and its auxiliary equipment are from the dangerous effects of non-stationary processes. Equipment damage statistics show that the vast majority of failures occur precisely at the time of transient operating conditions, when one or another set of parameters changes. In order to avoid the development of an emergency situation, use emergency stop turbines: with or without vacuum failure.
If the vacuum fails, the turbine (for turbines with a rotor speed of 3000 rpm) should be immediately stopped at following cases: when increasing the speed above 3360 rpm; when there is a sudden increase in vibration by 20 microns (vibration velocity 1 mm/s) or more on any of the bearings; if there is a sudden increase in oil temperature at the drain of any bearing above 70°C; when the oil pressure on the bearings drops below 0.15 MPa; when the babbitt temperature of any of the bearings rises above 100°C.
A sudden forced stop is also necessary in case of any shocks in the flow part of the turbine, rupture of steam lines, or any ignition in the turbine or generator.
Stopping without breaking the vacuum is provided for the following deviations from the normal operating mode: when the parameters of fresh steam or reheat steam deviate by the amount: up to ±20°C – in temperature and up to +0.5 MPa – in fresh steam pressure; when there is a sudden change in the temperature of fresh steam or reheat steam at a rate of more than 2°C per minute; after 2 minutes of generator operation in motor mode; if the atmospheric membranes in the exhaust pipe of the low pressure cylinder are damaged; when oil leaks are detected.
Turbine protection systems for high-power steam turbines provide for stopping when the following values are reached: when the axial shift of the rotor reaches –1.5 mm towards the regulator or +1.0 mm towards the generator (the protection is triggered when the vacuum in the capacitors fails); when the relative expansion of RND-2 (low pressure rotor) reaches –3.0 mm (rotor shorter than the housing) or +13.0 mm (rotor longer than the housing); when the temperature of the LPC exhaust pipes increases to 90°C and above; when the oil level in the oil tank drops by 50 mm (immediate shutdown of the turbine is necessary).
The operation of turbines at full or partial constant load is provided in accordance with the factory operating instructions. Starting the turbine is also regulated by detailed factory instructions and does not allow deviations from given schedules launch.
General information. On ships navy main and auxiliary steam turbo mechanisms (turbogenerators, turbopumps, turbofans) are operated; all of them undergo annual inspections, during which the following is carried out: external inspection, readiness for action, operation in action, serviceability of maneuvering and starting devices and devices remote control, and also checks the serviceability of mounted and drive mechanisms.
Maintenance steam turbine includes carrying out scheduled preventive inspections (PPO) and repairs (SPR), adjusting and tuning turbine elements, troubleshooting, checking equipment for compliance with technical specifications, restoring lost properties, as well as taking measures to preserve turbines when they are inactive.
Depending on the volume and nature of the work performed, maintenance is divided into daily, monthly and annual.
Daily maintenance includes the following basic operations:
- visual inspection;
- removal of fuel, oil and water leaks;
- removal of traces of corrosion;
- vibration measurement.
Dismantling and dismantling of turbines. According to the manufacturer's instructions, scheduled openings of turbines are carried out. The purpose of opening turbines is to evaluate technical condition parts, cleaning its flow part from corrosion, carbon deposits and scale.
Disassembly of the turbine begins no earlier than 8-12 hours after it is stopped, that is, after cooling, when the temperature of the housing walls reaches equal temperature ambient air (about 20 C).
If the turbine is dismantled for transportation to the workshop, then the next order dismantling work:
- disconnect the turbine from the incoming steam;
- drain or pump out water from the condenser;
- pump oil out of the turbine or drain it, freeing the oil system;
- remove fittings and instrumentation;
- disconnect pipelines directly connected to the turbine or that interfere with its dismantling from the foundation;
- remove the turbine casing and insulation;
- dismantle handrails, remove platforms and shields;
- remove the quick-closing valve of the receiver and bypass valves;
- disconnect the turbine rotor from the gearbox;
- insert the slings and secure them to the lifting device;
- release the foundation bolts and remove the turbine from the foundation. The stator cover is undermined using squeezing bolts, and the lifting
(lowering) it and the rotor are performed special device. This device consists of four screw columns and lifting mechanisms. Rulers are attached to the screw columns to control the lifting height of the stator cover or turbine rotor. When lifting the lid or rotor, stop every 100-150 mm and check the uniformity of their lifting. The same is done when lowering them.
Flaw detection and repair. Flaw detection of the turbine is carried out in two stages: before opening and after opening during disassembly. Before opening the turbine, the following are measured using standard instrumentation: axial run-up of the rotor in the thrust bearing, oil clearances in the bearings, clearances in the limiting speed controller.
Typical defects of a steam turbine include: deformation of the stator connector flanges, cracks and corrosion of the internal cavities of the stator; deformation and imbalance of the rotor; deformation of the working disks (weakening of their fit on the rotor shaft), cracks in the area of the keyways; erosive wear, mechanical and fatigue destruction of rotor blades; diaphragm deformation; erosive wear and mechanical damage to the nozzle apparatus and guide vanes; wear of rings of end and intermediate seals, bearings.
During turbine operation, thermal deformations of parts mainly occur due to violations of the Technical Operation Rules.
Thermal deformations arise as a result of uneven heating of the turbine during its preparation for start-up and during shutdown.
The operation of an unbalanced rotor causes vibration of the turbine, which can lead to breakage of the blades and bandage, and destruction of seals and bearings.
Steam turbine housing performed with a horizontal connector, which divides it into two halves. The lower half is the body, and the upper half is the lid.
The repair consists of restoring the density of the housing connector plane due to warping. Warping of the parting plane with gaps up to 0.15 mm is eliminated by scraping. After scraping is completed, the cover is put back in place and the presence of local gaps, which should not be more than 0.05 mm, is checked with a feeler gauge. Cracks, fistulas and corrosion pits in the turbine housing are cut and eliminated by welding and surfacing.
Steam turbine rotors. In main turbines, the rotors are most often made solid forged, while in auxiliary turbines the rotor is usually assembled, consisting of a shaft and a turbine impeller.
Rotor deformation (bending), which does not exceed 0.2 mm, is removed by mechanical processing, up to 0.4 mm by thermal straightening, and above 0.4 mm by thermomechanical straightening.
A rotor with cracks is replaced. Wear on the journals is eliminated by grinding. Ovality and conicality of the necks is allowed no more than 0.02 mm.
Working disks. Disks with cracks are replaced. The deformation of the disks is detected by the end runout and, if it does not exceed 0.2 mm, it is eliminated by turning the end of the disk on a machine. If the deformation is greater, the discs are subjected to mechanical straightening or replacement. Weakening of the disk fit on the shaft is eliminated by chrome-plating its mounting hole.
Disc blades. Erosive wear is possible on the blades and, if it does not exceed 0.5-1.0 mm, then they are filed down and ground by hand. In case of major damage, the blades are replaced. New blades are manufactured at turbine manufacturing plants. Before installing new blades, they are weighed.
If there is mechanical damage and separation of the band band of the working blades, it is replaced by removing the old band.
Turbine diaphragms. Any diaphragm consists of two halves: upper and lower. The upper half of the diaphragm is installed in the housing cover, and the lower half is installed in the lower half of the turbine housing. The repair involves eliminating warping of the diaphragm. The warpage of the diaphragm is determined on the slab using probe plates; for this, the diaphragm is placed with the rim on the side where the steam exits onto the slab and the presence of a probe is used to check for gaps between the rim and the slab.
Warping is eliminated by grinding or scraping the end of the rim on the slab for paint. Then, along the scraped end of the diaphragm rim, a landing groove is scraped in the turbine housing on the side of the steam outlet. This is done to achieve a tight fit of the diaphragm to the body, in order to reduce steam leaks. If there are cracks on the diaphragm rim, replace it.
Labyrinth (end) seals. By design, labyrinth seals can be simple type, elastic herringbone type, elastic comb type. When repairing seals, bushings and segments of labyrinth seals with damage are replaced, setting radial and axial clearances in accordance with the repair specifications.
Support bearings in turbines there may be slipping and rolling. In the main ships steam turbines use plain bearings. Repairing such bearings is similar to repairing diesel bearings. The size of the installation oil gap depends on the diameter of the rotor shaft journal. With a shaft journal diameter of up to 125 mm, the installation gap is 0.12-0.25 mm, and the maximum permissible is 0.18-0.35 mm. Rolling bearings (ball, roller) are installed in turbines of auxiliary mechanisms and they cannot be repaired.
Static balancing of discs and rotors. One of the reasons that causes vibration in a turbine is the imbalance of the rotating rotor and disks. Rotating parts may have one or more unbalanced masses. Depending on their location, static or dynamic imbalance of masses is possible. Static imbalance can be determined statically, without rotating the part. Static balancing is the alignment of the center of gravity with its geometric axis of rotation. This is achieved by removing metal from the heavy part of the part or adding it to its light part. Before balancing, check the radial runout of the rotor, which should be no more than 0.02 mm. Static balancing of parts operating at a rotation speed of up to 1000 min-1 is carried out in one stage, and at a higher rotation speed - in two stages.
At the first stage, the part is balanced to its indifferent state, in which it stops in any position. This is achieved by determining the position of the heavy point, and then selecting and attaching a balancing weight on the opposite side.
After balancing the part, a permanent load is attached to its light side instead of a temporary load, or the corresponding amount of metal is removed from the heavy side and the balancing is completed.
The second stage of balancing is to eliminate the residual imbalance (imbalance) remaining due to the inertia of the part and the presence of friction between them and the supports. To do this, the surface of the end of the part is divided into six to eight equal parts. Then, the part with the temporary load is installed so that it is in the horizontal plane (point 1). At this point, the mass of the temporary load is increased until the part comes out of equilibrium and begins to rotate. After this operation, the load is removed and weighed on scales. Work is performed in the same sequence for the remaining points of the part. Based on the data obtained, a curve is constructed, which, if balancing is performed accurately, should have the shape of a sinusoid. The maximum and minimum points are found on this curve. The maximum point of the curve corresponds to the light part of the part, and the minimum point corresponds to the difficult place. The accuracy of static balancing is estimated by the inequality:
Where TO— mass of the balancing load, g;
R— installation radius of temporary load, mm;
G— rotor mass, kg;
Lst— maximum permissible displacement of the center of gravity of the part from its axis of rotation, µm. The maximum permissible displacement of the center of gravity of a part is found from the diagram of the maximum permissible displacement of the center of gravity at static balancing, according to the turbine’s passport data or according to the formula:
Where n— rotor rotation speed, s-1.
Dynamic balancing. During dynamic balancing, all rotor masses are reduced to two masses lying in the same diametrical plane, but different sides from the axis of rotation. Dynamic imbalance can only be determined by the centrifugal forces that arise when the part rotates at a sufficient speed. The quality of dynamic balancing is assessed by the amplitude of rotor oscillations at the critical speed of its rotation. Balancing is carried out on a special stand in the factory. The stand has pendulum or swing type supports (stand types 9B725, 9A736, MS901, DB 10, etc.). The turbine rotor is placed on two spring bearings mounted on the frame supports and connected to the electric motor. Rotating electric motor The turbine rotor is determined by its critical rotation frequency, while measuring in turn the maximum amplitudes of vibration of the rotor journals on each side. Then, each side of the rotor is marked around the circumference into 6-8 equal parts and the mass of the test load for each side is calculated. Balancing begins on the side of the bearing that has a large vibration amplitude. The second bearing is secured. The test weight is attached at point 1 and the maximum amplitude of oscillation of the rotor neck is measured at the critical frequency of its rotation. Then the load is removed, secured at point 2 and the operation is repeated. Based on the data obtained, a graph is constructed from which the maximum and minimum amplitudes and the average value of the amplitude are determined, and based on its value, the mass of the balancing load is determined. The bearing with a larger vibration amplitude is fixed, and the second one is released from the fastening. The balancing operation of the second side is repeated in the same sequence. The balancing results are assessed using the following inequality:
Where aoct— amplitude of oscillations of the rotor ends, mm;
R— radius of balancing weight attachment, mm;
G— part of the rotor mass attributable to this support, kg;
Lct— permissible displacement of the center of gravity from the axis of rotation of the rotor during dynamic balancing, µm.
Turbine assembly includes alignment of the rotor and diaphragms.
Rotor alignment. Before centering the rotor, the sliding bearings are adjusted to the beds and journals of the rotor. Then the rotor is aligned relative to the bore axis under the turbine end seal races. When aligning the rotor and diaphragms, a false shaft (process shaft) is used, which is placed on bearings. Then the gaps between the shaft journal and the cylindrical surface under the seals are measured in the vertical and horizontal planes. The permissible displacement of the rotor axis relative to the axis of the bores for the seals is allowed up to 0.05 mm. Equality of the gaps indicates good alignment, and if not, then the rotor axis is aligned.
Closing the turbine. Before laying the rotor, its journals and bearings are lubricated with clean oil. The rotor is then placed on the bearings and the cover is lowered. After crimping the cover, the ease of rotation of the rotor is checked. To seal the parting surfaces of a turbine operating at pressures above 3.5 MPa and temperatures up to 420 C, “Sealant” paste or other mastics are used. In this case, the threads of nuts, studs and simple bolts covered with a thin layer of graphite, and the fit bolts are lubricated with mercury ointment.
Testing turbines after repair. Repaired turbo mechanisms must first be tested at the SRZ stand, then mooring and sea trials must be carried out. In the absence of stands at the shipyard, turbo mechanisms are subjected only to mooring and sea trials. Mooring tests consist of running-in, adjustment and testing of turbo mechanisms according to a bench test program.
All preparations for the test start-up of the turbine installation (checking the operation of the valves, warming up the turbine and steam pipelines, lubrication system, etc.) are carried out in full accordance with the “Rules for the maintenance and care of ship steam turbines.” In addition, the lubrication system and bearings are pumped with hot oil at a temperature of 40-50 C using a lubrication pump. To clean the lubrication system from contaminants, temporary filters made of copper mesh and gauze, etc. are installed in front of the bearings. They are periodically opened, washed and put back in place. Pump the oil until there is no sediment on the filters. After pumping, the oil is drained from the supply tank, the tank is cleaned and filled with fresh oil.
Before starting, the turbine is turned with a shaft turning device, and the locations of the turbine and gearbox bearings, the area of the flow path, seals and gears are carefully listened with a stethoscope. If there are no comments, the turbine rotor is turned with steam, bringing its rotation to a frequency of 30-50 min -1, and the steam is immediately shut off. The secondary start of the turbine is carried out if no malfunctions are detected during cranking.
If there is any extraneous sound in the turbine, it is immediately stopped, inspected, the causes of malfunctions are identified and measures are taken to eliminate them.
The operation of the turbo mechanism at idle is checked with a gradual increase in the turbine rotor speed to the nominal value and at the same time the operation of the speed regulator, quick-closing valve, vacuum condenser, etc.
During sea trials, the technical and economic indicators of the turbo mechanism are determined in all operating modes.
The RMC Holding company specializes in the maintenance and repair of steam turbines. The service includes both scheduled and unscheduled maintenance of steam turbine equipment, engineering, turbine operation support, and defect elimination auxiliary installations, as well as repair of components and assemblies, reconstruction and modernization of steam turbine equipment. Our specialists are ready to provide qualified technical support throughout the entire life of the equipment.
Maintenance of steam turbine equipment
Timely maintenance of steam turbines guarantees reliable and uninterrupted operation, as well as high performance.
In progress permanent job Turbine equipment is subject to moral and physical wear and tear, so periodic maintenance and repair of installations is required.
On average, the service life of steam turbines is 250 thousand hours. In addition, during the operation of the equipment on different components installations, certain defects arise that provoke a deterioration in the properties of the metal. Creep processes begin, thermal fatigue occurs, and the structure of the material is destroyed. Such changes require urgent decisions to be made to renew the resource and reconstruct the park as a whole.
The more resource hours used, the higher the recovery costs technical indicators. This is due to an increase in the number of accumulated defects on components and assemblies and a decrease in equipment performance. In order to avoid extra costs, it is necessary to carry out scheduled maintenance of equipment in a timely manner.
Steam turbine modernization
Reconstruction and modernization of steam turbines pursues the following goals:
- updating the resource of high-temperature units;
- replacement of parts with components with increased operating parameters;
- increasing equipment capacity;
- increase in efficiency;
- extension of service life.
- updating components and assemblies;
- replacing the SD rotor with a new one;
- optimization of the drainage system;
- installation of sealed control diaphragms;
- improvement of regulatory and protection systems.
The process of modernizing steam turbines is a whole complex of activities that require high professionalism of engineers and the performance of complex and labor-intensive work. The implementation of such projects requires an average of 1-1.5 years from the date of ordering.
The RMC Holding company carries out maintenance and repair of steam turbines, as well as modernization of the turbine fleet both in thermal power plants and in its own workshops. All necessary components, assemblies and various components are delivered to the customer’s site according to the project, all necessary components are developed and presented technical documentation. Our specialists provide control, as well as designer’s supervision in the event of repair work on the territory of the customer's thermal power plant.
By ordering our services, the client receives turbines with an increased resource and significantly improved technical, physical and economic indicators equipment.
To order services by maintenance, modernization and reconstruction of steam turbines, you just need to call the phone number listed on the website, or fill out an application online. Our specialists will accept your order and answer all your questions regarding the repair of steam turbines, providing free consultation. We work not only in Moscow, but also in Krasnodar, Tula, Voronezh and other cities of Russia.