V.L. Gudzyuk, P. Shomov, P.A. Perov, Reducing steam losses when draining a steam pipeline through a retaining washer. About steam and water losses at thermal power plants

Ph.D. S.D. Sodnomova, Associate Professor, Department of Heat and Gas Supply and Ventilation, East Siberian State technological university, Ulan-Ude, Republic of Buryatia

Currently, the balance of heat supply and consumption in steam supply systems is determined by readings from metering devices at the heat source and at consumers. The difference in the readings of these devices is attributed to actual heat losses and is taken into account when setting tariffs for thermal energy in the form of steam.

Previously, when the steam pipeline was operating close to the design load, these losses amounted to 1015%, and no one had any questions about it. In the last decade, due to the decline industrial production there was a change in work schedule and a reduction in steam consumption. At the same time, the imbalance between heat consumption and supply increased sharply and began to amount to 50-70%.

Under these conditions, problems arose, primarily from consumers who considered it unreasonable to include such large losses of thermal energy in the tariff. What is the structure of these losses? How to consciously address issues of increasing the efficiency of steam supply systems? To resolve these issues, it is necessary to identify the structure of the imbalance and evaluate the standard and excess heat losses.

The program has been improved to quantify imbalances hydraulic calculation superheated steam steam pipeline, developed at the department for educational purposes. Understanding that as steam consumption among consumers decreases, coolant velocities decrease and relative heat losses during transport increase. This leads to the fact that the superheated steam goes into a saturated state with the formation of condensate. Therefore, a subroutine was developed that allows: to determine the area where superheated steam passes into a saturated state; determine the length at which steam begins to condense and then perform a hydraulic calculation of the saturated steam steam pipeline; determine the amount of condensate formed and heat loss during transport. To determine the density, isobaric heat capacity and latent heat of vaporization from the final steam parameters (P, T), simplified equations were used, obtained from

based on the approximation of tabular data describing the properties of water and water vapor in the pressure range of 0.002+4 MPa and saturation temperatures up to 660 °C.

Standard heat losses in environment were determined by the formula:

where q - specific linear heat losses steam lines; L is the length of the steam pipeline, m; β - local heat loss coefficient.

Heat losses associated with steam leaks were determined using the following method:

where Gnn is the normalized steam loss for the period under consideration (month, year), t; ί η - enthalpy of steam at average pressures and temperatures of steam along the main line at the heat source and at consumers, kJ/kg; ^ - enthalpy cold water, kJ/kg.

Standardized steam losses for the period under review:

where V™ is the average annual volume steam networks, m 3; p p - steam density at average pressure and temperature along the lines from the heat source to the consumer, kg/m 3 ; n - average annual number of operating hours of steam networks, hours.

The metrological component of underestimation of steam consumption was determined taking into account the rules RD-50-213-80. If the flow rate is measured under conditions in which the steam parameters differ from the parameters adopted for calculating the restriction devices, then to determine the actual flow rates from the instrument readings, it is necessary to recalculate using the formula:

where Qm. a. - actual mass steam consumption, t/h; Q m - mass flow steam according to instrument readings, t/h; р А - actual steam density, kg/m3; ρ - estimated steam density, kg/m 3.

To assess heat losses in the steam supply system, the steam pipeline POSH in Ulan-Ude was considered, which is characterized by the following indicators:

■ total steam consumption for February - 34512 t/month;

■ average hourly steam consumption - 51.36 t/h;

■ average temperature steam - 297 O C;

■ average steam pressure - 8.8 kgf/cm2;

■ average outside air temperature - -20.9 O C;

■ length of the main line - 6001 m (of which 500 mm in diameter - 3289 m);

■ heat imbalance in the steam pipeline - 60.3%.

As a result of the hydraulic calculation, the steam parameters at the beginning and end of the calculation section, the coolant velocity were determined, and areas where condensate formation and associated heat losses occur were identified. The remaining components were determined using the above method. The calculation results show that with an average hourly supply of steam from the thermal power plant of 51.35 t/h, 29.62 t/h (57.67%) is delivered to consumers, the loss of steam consumption is 21.74 t/h (42.33%). Of these, steam losses are as follows:

■ with formed condensate - 11.78 t/h (22.936%);

■ metrological due to the fact that consumers do not take into account corrections to instrument readings - 7.405 t/h (14.42%);

■ unaccounted steam losses - 2.555 t/h (4.98%). Unaccounted steam losses can be explained

averaging of parameters during the transition from the average monthly balance to the average hourly balance, some approximations in calculations and, in addition, the instruments have an error of 2-5%.

As for the balance of thermal energy of released steam, the calculation results are presented in the table. This shows that with an imbalance of 60.3%, the standard heat losses are 51.785%, and the excess heat losses not taken into account by the calculation are 8.514%. Thus, the structure of heat losses has been determined, and a method has been developed to quantify the imbalance of steam and thermal energy consumption.

Table. Results of calculations of thermal energy losses in the steam pipeline POSH in Ulan-Ude.

Name of quantities	GJ/h	%
General indicators
Average hourly heat release from thermal power plant collectors	154,696	100
Useful average hourly heat supply to consumers	61,415	39,7
Actual heat losses in the steam pipeline POS	93,28	60,3
Standard heat losses	70,897	45,83
Operational technological losses thermal energy, of which: Heat losses to the environment Heat energy losses with standard steam leaks Heat loss with condensate	43,98	28,43
Metrological losses due to underestimation of heat without introducing a correction	9,212	5,955
Total
Standard losses of thermal energy	80,109	51,785
Excessive heat losses not taken into account by calculation	13,171	8,514

Literature

1. Abramov S.R. Methodology for reducing heat losses in steam pipelines of heating networks / Conference materials " Heat networks. Modern solutions", May 17-19, 2005. NP "Russian Heat Supply".

2. Sodnomova S.D. On the issue of determining the components of imbalance in steam supply systems / Materials of the international scientific-practical conference"Construction complex of Russia: Science, education, practice." - Ulan-Ude: Publishing House of the All-Russian State Technical University, 2006.

3. Rivkin S.L., Aleksandrov A.A. Thermophysical properties of water and water vapor. - M.: Energy 1980 - 424 p.

4. Determination of operational technological costs (losses) of resources taken into account when calculating services for the transfer of thermal energy and coolant. Resolution of the Federal Energy Commission of the Russian Federation dated May 14, 2003 No. 37-3/1.

5. RD-50-213-80. Rules for measuring the flow of gases and liquids using standard restriction devices. M.: Standards Publishing House. 1982.

1 – electric generator; 2 – steam turbine; 3 – control panel; 4 – deaerator; 5 and 6 – bunkers; 7 – separator; 8 – cyclone; 9 – boiler; 10 – heating surface (heat exchanger); 11 – chimney; 12 – crushing room; 13 – reserve fuel warehouse; 14 – carriage; 15 – unloading device; 16 – conveyor; 17 – smoke exhauster; 18 – channel; 19 – ash catcher; 20 – fan; 21 – firebox; 22 – mill; 23 – pumping station; 24 – water source; 25 – circulation pump; 26 – regenerative heater high pressure; 27 – feed pump; 28 – capacitor; 29 – installation chemical cleaning water; 30 – step-up transformer; 31 – regenerative heater low pressure; 32 – condensate pump.

The diagram below shows the composition of the main equipment of a thermal power plant and the interconnection of its systems. From this diagram you can trace general sequence technological processes occurring at thermal power plants.

Designations on the TPP diagram:

1. Fuel economy;
2. fuel preparation;
3. intermediate superheater;
4. high pressure part (HPV or CVP);
5. low pressure part (LPP or LPC);
6. electric generator;
7. auxiliary transformer;
8. communication transformer;
9. The main thing switchgear;
10. condensate pump;
11. circulation pump;
12. source of water supply (for example, river);
13. (PND);
14. water treatment plant (WPU);
15. thermal energy consumer;
16. return condensate pump;
17. deaerator;
18. feed pump;
19. (PVD);
20. slag removal;
21. ash dump;
22. smoke exhauster (DS);
23. chimney;
24. blower fan (DV);
25. ash catcher

Description of the TPP technological scheme:

Summarizing all of the above, we obtain the composition of a thermal power plant:

• fuel management and fuel preparation system;
• boiler installation: a combination of the boiler itself and auxiliary equipment;
• turbine installation: steam turbine and its auxiliary equipment;
• water treatment and condensate purification installation;
• system technical water supply;
• ash removal system (for thermal power plants operating on solid fuel);
• electrical equipment and electrical equipment control system.

Fuel facilities, depending on the type of fuel used at the station, include a receiving and unloading device, transport mechanisms, fuel storage facilities for solid and liquid fuels, devices for preliminary fuel preparation (crushing plants for coal). The fuel oil facility also includes pumps for pumping fuel oil, fuel oil heaters, and filters.

Preparation solid fuel for combustion consists of grinding and drying it in a dust preparation plant, and the preparation of fuel oil consists of heating it, cleaning it from mechanical impurities, and sometimes treating it with special additives. With gas fuel everything is simpler. Preparation of gas fuel comes down mainly to regulating the gas pressure in front of the boiler burners.

The air required for fuel combustion is supplied to the combustion space of the boiler by blower fans (AD). The products of fuel combustion - flue gases - are sucked off by smoke exhausters (DS) and discharged through chimneys into the atmosphere. A set of channels (air ducts and gas ducts) and various elements equipment through which air and flue gases pass forms the gas-air path of a thermal power plant (heating plant). The smoke exhausters, chimney and blower fans included in it constitute a draft installation. In the fuel combustion zone, the non-combustible (mineral) impurities included in its composition undergo chemical and physical transformations and are partially removed from the boiler in the form of slag, and a significant part of them is carried away by flue gases in the form fine particles ash. For protection atmospheric air from ash emissions, ash collectors are installed in front of smoke exhausters (to prevent their ash wear).

Slag and captured ash are usually removed hydraulically to ash dumps.

When burning fuel oil and gas, ash collectors are not installed.

When fuel is burned, chemically bound energy is converted into thermal energy. As a result, combustion products are formed, which in the heating surfaces of the boiler give off heat to the water and the steam generated from it.

The totality of equipment, its individual elements, and pipelines through which water and steam move form the station’s steam-water path.

In the boiler, the water is heated to saturation temperature, evaporates, and the saturated steam formed from the boiling boiler water is overheated. From the boiler, superheated steam is sent through pipelines to the turbine, where it is thermal energy turns into a mechanical one, transmitted to the turbine shaft. The steam exhausted in the turbine enters the condenser, transfers heat to the cooling water and condenses.

At modern thermal power plants and combined heat and power plants with units with a unit capacity of 200 MW and above, intermediate superheating of steam is used. In this case, the turbine has two parts: a high pressure part and a low pressure part. The steam exhausted in the high-pressure section of the turbine is sent to the intermediate superheater, where additional heat is supplied to it. Next, the steam returns to the turbine (to the low pressure part) and from it enters the condenser. Intermediate superheat steam increases the efficiency of the turbine unit and increases the reliability of its operation.

The condensate is pumped out of the condenser by a condensation pump and, after passing through low-pressure heaters (LPH), enters the deaerator. Here it is heated by steam to a saturation temperature, while oxygen and carbon dioxide are released from it and removed into the atmosphere to prevent equipment corrosion. Deaerated water, called feedwater, is pumped through high-pressure heaters (HPH) into the boiler.

The condensate in the HDPE and deaerator, as well as the feed water in the HDPE, are heated by steam taken from the turbine. This heating method means returning (regenerating) heat to the cycle and is called regenerative heating. Thanks to it, the flow of steam into the condenser is reduced, and therefore the amount of heat transferred to the cooling water, which leads to increasing efficiency steam turbine plant.

The set of elements that provide cooling water to the condensers is called the technical water supply system. This includes: a water supply source (river, reservoir, cooling tower), circulation pump, inlet and outlet water pipes. In the condenser, approximately 55% of the heat of the steam entering the turbine is transferred to the cooled water; this part of the heat is not used to generate electricity and is wasted uselessly.

These losses are significantly reduced if partially exhausted steam is taken from the turbine and its heat is used for the technological needs of industrial enterprises or for heating water for heating and hot water supply. Thus, the station becomes a combined heat and power plant (CHP), providing combined generation of electrical and thermal energy. At thermal power plants, special turbines with steam extraction are installed - so-called cogeneration turbines. The steam condensate delivered to the heat consumer is returned to the thermal power plant by a return condensate pump.

At thermal power plants there are internal losses steam and condensate, due to incomplete tightness of the steam-water path, as well as the unrecoverable consumption of steam and condensate for the technical needs of the station. They constitute approximately 1 - 1.5% of the total steam consumption for turbines.

At thermal power plants there may also be external losses of steam and condensate associated with the supply of heat to industrial consumers. On average they are 35 - 50%. Internal and external losses of steam and condensate are replenished with additional water pre-treated in the water treatment plant.

Thus, boiler feed water is a mixture of turbine condensate and make-up water.

The electrical equipment of the station includes an electric generator, a communication transformer, a main switchgear, and a power supply system for the power plant's own mechanisms through an auxiliary transformer.

The control system collects and processes information about the progress technological process and equipment condition, automatic and remote control of mechanisms and regulation of basic processes, automatic protection equipment.

Life modern man on Earth is unthinkable without the use of energy
both electrical and thermal. Most of this energy in everything
the world is still producing thermal power plants: To their share
accounts for about 75% of the electricity generated on Earth and about 80%
produced electricity in Russia. Therefore, the question of reducing
energy consumption for the production of heat and electrical energy not far
idle.

Types and schematic diagrams of thermal power plants

The main purpose of power plants is to generate
electricity for lighting, supplying industrial and
agricultural production, transport, utilities and
household needs. Other purposes of power plants (thermal)
is supply residential buildings, institutions and enterprises with heat for
heating in winter and hot water for municipal and domestic purposes or
steam for production.

Thermal power stations(TPP) for combined generation
electrical and thermal energy (for district heating) are called
combined heat and power plants (CHP), and thermal power plants intended only for
electricity production are called condensing
power plants (PPS) (Fig. 1.1). IES are equipped steam turbines,
the exhaust steam of which enters the condensers, where it is maintained
deep vacuum for best use steam energy during production
electricity (Rankine cycle). Steam from the extractions of such turbines is used
only for regenerative heating of exhaust steam condensate and
feed water boilers

Figure 1. Schematic diagram IES:

1 - boiler (steam generator);
2 - fuel;
3 - steam turbine;
4 - electric generator;

6 - condensate pump;

8 - steam boiler feed pump

CHP plants are equipped with steam turbines with steam extraction for supply
industrial enterprises (Fig. 1.2, a) or for heating network water,
supplied to consumers for heating and household needs
(Fig. 1.2, b).

Figure 2. Principle thermal diagram CHP

a- industrial thermal power plant;
b- heating CHP;

1 - boiler (steam generator);
2 - fuel;
3 - steam turbine;
4 - electric generator;
5 — turbine exhaust steam condenser;
6 - condensate pump;
7— regenerative heater;
8 — steam boiler feed pump;
7-collection condensate tank;
9- heat consumer;
10—mains water heater;
11-net pump;
12-condensate pump for network heater.

Since approximately the 50s of the last century, thermal power plants have been used to drive
electric generators began to be used gas turbines. At the same time, in
fuel combustion gas turbines have become widespread
at constant pressure with subsequent expansion of combustion products into
turbine flow path (Brayton cycle). Such installations are called
gas turbine (GTU). They can only work for natural gas or on
liquid high-quality fuel (solar oil). These energy
installations require air compressor, power consumption
which is large enough.

The schematic diagram of the gas turbine unit is shown in Fig. 1.3. Thanks a lot
maneuverability ( quick start into operation and loading) gas turbine units have been used
in the energy sector as peak installations to cover sudden
power shortage in the energy system.

Figure 3. Schematic diagram of a combined cycle plant

1-compressor;
2-combustion chamber;
3-fuel;
4-gas turbine;
5-electric generator;
6-steam turbine;
7-recovery boiler;
8- steam turbine condenser;
9-condensate pump;
10-regenerative heater in the steam cycle;
11-feed pump of waste heat boiler;
12-chimney.

Problems of CHP

Along with the well-known problems high degree equipment wear
and widespread use of insufficiently efficient gas
steam turbine units in lately Russian thermal power plants are faced with
another relatively new threat to inefficiency. Whatever
strangely, it is connected with the growing activity of heat consumers in the region
energy saving.

Today, many heat consumers are starting to implement measures to
saving thermal energy. These actions primarily cause damage
operation of thermal power plants, as they lead to a reduction in the thermal load on the station.
Economical mode of operation of the thermal power plant - thermal, with a minimum supply of steam to
capacitor. With a decrease in the consumption of selected steam, the thermal power plant is forced to
to complete the task of generating electrical energy, increase the supply
steam into the condenser, which leads to an increase in cost
generated electricity. Such uneven work leads to
increase specific costs fuel.

In addition, in the case of full load on the generation of electrical energy
and low consumption of selected steam, the thermal power plant is forced to discharge
excess steam into the atmosphere, which also increases the cost
electricity and thermal energy. Using the below
energy-saving technologies will lead to a reduction in costs for own
needs, which helps to increase the profitability of thermal power plants and increase
controlling the consumption of thermal energy for own needs.

Ways to improve energy efficiency

Let's consider the main sections of the thermal power plant: typical mistakes their organizations and
operation and the possibility of reducing energy costs for heat generation
and electrical energy.

Fuel oil facilities of thermal power plant

Fuel oil facilities include: equipment for receiving and unloading wagons
with fuel oil, fuel oil supply warehouse, fuel oil pumping station with fuel oil heaters,
steam satellites, steam and water heaters.

Volume of steam and heating water consumption to maintain operation
fuel oil economy is significant. At gas and oil thermal power plants (when using
steam for heating fuel oil without condensate return) productivity
desalting plant increases by 0.15 t per 1 ton of combustion
fuel oil.

Losses of steam and condensate in fuel oil facilities can be divided into two
categories: returnable and non-refundable. Non-returnable steam includes:
used for unloading cars when heated by mixing flows, steam
for purging steam pipelines and steaming fuel oil pipelines. Total steam volume
used in steam heaters, fuel oil heaters, heaters
pumps in fuel oil tanks must be returned to the CHP cycle in the form
condensate

A typical mistake in organizing a fuel oil facility at a thermal power plant is the lack of
condensate traps on steam satellites. Differences between steam satellites in length and
operating mode lead to different heat removal and the formation of
from steam satellites of the steam-condensate mixture. The presence of condensate in the steam
can lead to water hammer and, as a consequence, failure
construction of pipelines and equipment. No controlled outlet
condensate from heat exchangers, also leads to the passage of steam into
condensate line. When draining condensate into an oil-contaminated tank
condensate, there is a loss of steam in the condensate line in
atmosphere. Such losses can amount to up to 50% of steam consumption for fuel oil.
farming.

Tying steam traps with condensate traps, installation on
heat exchangers of the fuel oil outlet temperature control system
ensures an increase in the proportion of returned condensate and a reduction in consumption
couple on fuel oil farm up to 30%.

From personal practice I can give an example when bringing the system
regulation of fuel oil heating in fuel oil heaters into working order
condition made it possible to reduce steam consumption for fuel oil pumping station on
20%.

To reduce steam consumption and fuel oil consumption
electricity can be transferred to fuel oil recycling back to
fuel oil tank. According to this scheme, it is possible to pump fuel oil from the tank to
tank and heating of fuel oil in fuel oil tanks without turning on additional
equipment, which leads to savings in thermal and electrical energy.

Boiler equipment

Boiler equipment includes energy boilers, air
air heaters, air heaters, various pipelines, expanders
drainages, drainage tanks.

Noticeable losses at thermal power plants are associated with continuous blowing of boiler drums.
To reduce these losses, install on the purge water lines
purge expanders. Schemes with one and two stages are used
extensions.

In a boiler blowdown scheme with one steam expander from the last
is usually sent to the deaerator of the main turbine condensate. Right there
steam arrives from the first expander at two-stage scheme. Steam from
the second expander is usually sent to atmospheric or vacuum
deaerator of make-up water of a heating network or into a station collector
(0.12-0.25 MPa). The purge expander drain is fed into the cooler.
blowing, where it is cooled with water sent to the chemical shop (for
preparation of additional and make-up water), and then discharged. So
Thus, blowdown expanders reduce losses of blowdown water and
increase the thermal efficiency of the installation due to the fact that greater
Part of the heat contained in the water is usefully used. At
installing the regulator continuous blowing to the maximum
salt content increases the efficiency of the boiler, reduces the volume consumed by
replenishment of chemically purified water, thereby achieving an additional effect
by saving reagents and filters.

With an increase in flue gas temperature by 12-15 ⁰C, heat loss
increase by 1%. Using the heater control system
air of boiler units based on air temperature leads to the exclusion
water hammer in the condensate pipeline, reducing the air temperature at the inlet
regenerative air heater, reducing the temperature of the exhaust
gases

According to the heat balance equation:

Q p =Q 1 +Q 2 +Q 3 +Q 4 +Q 5

Q p - available heat per 1 m3 of gaseous fuel;
Q 1 - heat used to generate steam;
Q 2 - heat loss with exhaust gases;
Q 3 - losses due to chemical underburning;
Q 4 - losses from mechanical underburning;
Q 5 - losses from external cooling;
Q 6 - losses with physical heat of slag.

As the value of Q 2 decreases and Q 1 increases, the efficiency of the boiler unit increases:
Efficiency = Q 1 /Q p

At thermal power plants with parallel connections, situations arise when it is necessary
disconnecting sections of steam pipelines with opening drains in dead-end
areas. To visualize the absence of condensation of the steam line
the revisions are opened slightly, which leads to loss of steam. In case of installation
condensate traps on dead-end sections of steam pipelines, condensate,
generated in steam lines is disposed of in an organized manner into drainage tanks
or drain expanders, resulting in the possibility of triggering
saved steam at the turbine installation with the generation of electric power
energy.

So when resetting the transfer 140 ati after one revision, and provided that
steam-condensate mixture enters through the drainage, the span size and
the losses associated with this, Spirax Sarco specialists expect,
using a technique based on the Napier equation, or the outflow of a medium
through a hole with sharp edges.

When working with an open revision for a week, the steam loss will be 938
kg/h*24h*7= 157.6 tons, gas losses will be about 15 thousand nm³, or
underproduction of electricity in the region of 30 MW.

Turbine equipment

Turbine equipment includes steam turbines, heaters
high pressure, low pressure heaters, heaters
network, boiler rooms, deaerators, pumping equipment, expanders
drains, low point tanks.

will lead to a reduction in the number of violations of heating network operation schedules, and
malfunction of the chemically purified (chemically desalted) water preparation system.
Violation of the operating schedule of the heating network leads to losses due to overheating
heat and underheating leads to loss of profit (sale of less heat,
than possible). Temperature deviation raw water at the chemical workshop, leads:
when the temperature decreases, the performance of clarifiers deteriorates; when the temperature increases,
temperatures - to an increase in filter losses. To reduce consumption
steam for raw water heaters use water from the discharge
condenser, due to which the heat lost with circulating water in
atmosphere is used in the water supplied to the chemical shop.

The drainage expander system can be one- or two-stage.
With a single-stage system, steam from the drain expander enters
auxiliary steam collector, and is used in deaerators and
In various heaters, condensate is usually discharged into a drain tank
or tank low points. If the thermal power plant has steam for its own needs, two
different pressures, use two-stage system expanders
drainage. In the absence of level regulators in drain expanders
steam leaks with condensate from the high drainage expanders
pressure into the low pressure expander and then through the drain tank into
atmosphere. Installing drain expanders with level control can
lead to steam savings and reduction of condensate losses by up to 40% of the volume
steam-condensate mixture of steam pipeline drainage.

During startup operations on turbines, it is necessary to open drains and
turbine extractions. During turbine operation, the drains are closed. However
complete closure of all drainages is impractical, since due to
the presence in the turbine of stages where the steam is at boiling point, and
therefore, it may condense. With constantly open drains
steam is discharged through the expander into the condenser, which affects the pressure
in it. And when the pressure in the condenser changes by ±0.01 at
At constant steam flow, the change in turbine power is ±2%.
Manual regulation drainage system also increases the likelihood
errors.

I will give an example from personal practice confirming the need for strapping
turbine drainage system with condensate traps: after eliminating
defect that led to the shutdown of the turbine, the thermal power plant began to repair it
launch. Knowing that the turbine was hot, the operating personnel forgot to open
drainage, and when the extraction was turned on, a water hammer occurred with the destruction of part
turbine extraction steam line. As a result, emergency repairs were required
turbines. In the case of piping the drainage system with condensate traps,
this problem could have been avoided.

During the operation of thermal power plants, problems sometimes arise with violations
water chemistry mode of operation of boilers due to increased content
oxygen in feed water. One of the reasons for the violation of water chemistry
mode is a decrease in pressure in deaerators due to the lack
automatic pressure maintenance system. Violation of water chemistry
mode leads to wear of pipelines, increased corrosion of surfaces
heating, and as a result additional costs for equipment repairs.

Also, at many stations, units are installed on the main equipment
metering based on diaphragms. The diaphragms have normal dynamic
measurement range 1:4, which causes the problem of determining loads
during starting operations and minimal loads. Incorrect operation
flow meters leads to a lack of control over the correctness and
efficiency of equipment operation. Today, Spirax LLC
Sarco Engineering" is ready to present several types of flow meters with
measuring range up to 100:1.

In conclusion, let us summarize the above and list once again main measures to reduce energy costs of thermal power plants:

• Tying steam traps with condensate traps
• Installation of a fuel oil outlet temperature control system on heat exchangers
• Transferring fuel oil recirculation back to the fuel oil tank
• Connection with a control system for network and raw water heaters
• Installation of drain expanders with level control
• Piping the turbine drainage system with condensate traps
• Installation of metering units

You can always find more interesting information on our website in the section

V.L. Gudzyuk, leading specialist;
Ph.D. P.A. Shomov, director;
P.A. Perov, heating engineer,
Scientific and Technical Center "Industrial Energy" LLC, Ivanovo

Calculations and existing experience show that even simple and relatively cheap technical events to improve heat management at industrial enterprises lead to a significant economic effect.

Surveys of steam-condensate systems of many enterprises have shown that steam pipelines often lack drainage pockets for collecting condensate and condensate traps. For this reason, increased steam losses often occur. Simulation of steam outflow based on software product made it possible to determine that steam losses through steam line drains can increase up to 30% if a steam-condensate mixture passes through the drain, compared to the removal of condensate only.

Measurement data on the steam pipelines of one of the enterprises (table), the drains of which do not have pockets for collecting condensate or condensate traps, and are partially open throughout the year, showed that losses of thermal energy and funds can be quite large. The table shows that drainage losses from a DN 400 steam line can be even less than from a DN 150 steam line.

Table. The results of measurements on the steam pipelines of the surveyed industrial enterprise, the drains of which do not have pockets for collecting condensate and condensate traps.

By paying some attention to the work to reduce this type of loss at low cost, a significant result can be obtained, so the possibility of using the device was tested, general view which is shown in Fig. 1. It is installed on the existing steam pipe drain pipe. This can be done with the steam line running without shutting it down.

Rice. 1. Device for steam line drainage.

It should be noted that not just any condensate trap is suitable for a steam pipeline, and the cost of equipping one drain with a condensate trap ranges from 50 to 70 thousand rubles. There are usually a lot of drainages. They are located at a distance of 30-50 m from each other, in front of risers, control valves, manifolds, etc. The steam trap requires qualified maintenance, especially in winter period. Unlike heat exchanger, the amount of condensate removed and, moreover, used, in relation to the steam flow through the steam pipeline, is insignificant. Most often, the steam-condensate mixture from the steam pipeline is discharged into the atmosphere through drainage. Its quantity is regulated by the shut-off valve “by eye”. Therefore, reducing steam losses from the steam pipeline together with condensate can give good economic effect unless it is related to at great expense funds and labor. This situation occurs in many enterprises and is the rule rather than the exception.

This circumstance prompted us to check the possibility of reducing steam losses from the steam pipeline, in the absence, for some reason, of the possibility of equipping the steam pipeline drains with condensate traps according to the standard design scheme. The task was to minimal costs time and means to organize the removal of condensate from the steam pipeline when minimal loss pair.

As the most easily implemented and inexpensive way To solve this problem, the possibility of using a retaining washer was considered. The diameter of the hole in the retaining washer can be determined by a nomogram or by calculation. The operating principle is based on different conditions leakage of condensate and steam through the hole. Bandwidth the retaining washer for condensate is 30-40 times larger than for steam. This allows condensate to be continuously discharged with a minimum amount of passing steam.

First, it was necessary to make sure that it was possible to reduce the amount of steam discharged through the drainage of the steam line along with condensate in the absence of a sump pocket and a water seal, i.e. under conditions, unfortunately, often encountered in enterprises with low pressure steam pipelines.

Shown in Fig. 1 device has an inlet and two identically sized outlet washer holes. The photograph shows that a steam-condensate mixture emerges through a hole with a horizontal jet direction. This hole can be closed with a tap and used periodically when it is necessary to vent the device. If the tap in front of this hole is closed, condensate flows out of the steam line through the second hole with a vertical stream direction - this is the operating mode. In Fig. 1 it can be seen that when the tap is open and exiting through the side hole, the condensate is sprayed with steam, and at the exit through the bottom hole there is practically no steam.

Rice. 2. Operating mode of the steam line drainage device.

In Fig. 2 shows the operating mode of the device. The output is mainly a flow of condensate. This clearly shows that it is possible to reduce the steam flow through the retaining washer without a water seal, the need for which is the main reason limiting its use for steam line drainage, especially in winter time. In this device, the escape of steam from the steam line along with condensate is prevented not only by throttle washer, but also a special filter that limits the exit of steam from the steam line.

The effectiveness of several has been tested design options such a device for removing condensate from a steam line with a minimum steam content. They can be made either from purchased components or in a boiler room mechanical workshop, taking into account the operating conditions of a particular steam pipeline. A commercially available water filter that is capable of operating at the temperature of the steam in the steam line can also be used with minor modifications.

The cost of manufacturing or purchasing components for one descender is no more than several thousand rubles. The implementation of the measure can be carried out at the expense of operating costs, and is at least 10 times cheaper than using a condensate trap, especially in cases where there is no return of condensate to the boiler room.

The magnitude of the economic effect depends on technical condition, operating mode and operating conditions of a particular steam pipeline. The longer the steam line and larger number drainage outlets, and at the same time drainage is carried out into the atmosphere, the greater the economic effect. Therefore, in each specific case, preliminary consideration of the issue of feasibility is required. practical use the solution under consideration. There is no negative effect in relation to the drainage of the steam pipeline with the release of the steam-condensate mixture into the atmosphere through the valve, as is often the case. We believe that for further study and accumulation of experience, it is advisable to continue work on existing low-pressure steam pipelines.

Literature

1. Elin N.N., Shomov P.A., Perov P.A., Golybin M.A. Modeling and optimization of pipeline networks for steam pipelines of industrial enterprises // Bulletin of ISEU. 2015. T. 200, no. 2. pp. 63-66.

2. Baklastov A.M., Brodyansky V.M., Golubev B.P., Grigoriev V.A., Zorina V.M. Industrial heat power engineering and heating engineering: Handbook. M.: Energoatomizdat, 1983. P.132. Rice. 2.26.

Losses of steam and condensate from power plants are divided into internal and external. Internal losses include losses from leakage of steam and condensate in the system of equipment and pipelines of the power plant itself, as well as losses of blowdown water from steam generators.

To simplify the calculation, leakage losses are conventionally concentrated in the fresh steam line

Continuous purging is carried out to ensure reliable operation of the steam generator and obtain steam of the required purity.

D pr =(0.3-0.5)% D 0

D pr =(0.5-5)% D 0 - for chemically purified water

To reduce blowdown, it is necessary to increase the amount of air flow and reduce leakage losses.

The presence of steam and condensate losses leads to a decrease in the thermal efficiency of the ES. To make up for the loss of additional water requirements, the preparation of which requires additional costs. Therefore, steam and condensate losses need to be reduced.

For example, losses with blowdown water must be reduced from the full expander of the blowdown water separator.

Internal losses: Dw =D ut +D pr

D ut - losses from leaks

D pr - losses from purge water

At IES: Dw ≤1%D 0

Heating CHP: Dw ≤1.2%D 0

Prom. CHP: Dw ≤1.6%D 0

In addition to D TV at thermal power plants, when steam from the turbines is directly proportionally directed to industrial consumers.

D in =(15-70)%D 0

At heating CHP plants, heat is supplied to the consumer in a closed circuit than industrial. Steam. Heat exchange

Steam from the turbine outlet is condensed in an industrial-type heat exchanger and the GP condensate is returned to the electrical system. Stations.

The secondary coolant is heated and sent to the heat consumer

In this scheme there are no external condensate losses

In the general case: D sweat = D W + D in - CHP

IES and CHP with closed circuit D cat =D Tue

Heat losses Dpr are reduced in blowdown water coolers. The blowdown water is cooled to feed the heating network and feeder plant.

20 Balance of steam and water at the power plant.

To calculate the thermal scheme, determine the steam flow to the turbines, the productivity of steam generators, energy indicators, etc., it is necessary to establish, in particular, the basic relationships of the material balance of steam and water of the power plant

Material balance of the steam generator: D SG = D O + D UT or D PV = D SG + D PR.

material balance of the turbine unit: D O = D K + D r + D P.

Material balance heat consumer: D P = D OK + D VN.

Internal losses of steam and condensate: D IN = D UT + D" PR.

Material balance for feed water: D PV = D K + D r + D OK +D" P + D DW.

Additional water must cover internal and external losses:

D DV = D IN + D HV = D UT + D" PR + D HV

Consider a purge water separator-expander

r s<р пг

h pr =h / (p pg)

h // p =h // (p s)

h / pr =h / (p s)

The heat and material balance of the separator is compiled

Thermal: D pr h pr =D / p h // p +D / pr h / pr

D / pr =D pr (h pr -h / pr)/ h // p -h / pr

D / n = β / n D pr; β/p ≈0.3

D / pr =(1-β / n) D pr

The calculated flow rate of purge water is determined from the material balance of the applications. C PV (kg/t) - concentration of impurities in PV

C pg - permissible concentration of impurities in boiler water

C n - concentration of impurities in steam

D PV = D PG + D PR – material balance

D PV S p = D PR - S pg + D PG S p

D PR = D PG *; D PR = ; α pr =D pr /D 0 =

The higher the amount of PV then C pg / C uv →∞ and then α pr →0

The amount of PV depends on the amount of additional.

In the case of direct-flow steam generators, water is not purged and the supply air must be especially clean.