Selection of equipment and calculation of thermal efficiency indicators of a combined heat and power plant

4. Description of the thermal circuit diagram of the CHP plant

The thermal circuit diagram is the basis of the designed power plant. As a result of calculations, the consumption is determined fresh steam per turbine, to control the correctness of the choice of initial data, the values ​​of energy indicators are used (specific consumption of equivalent fuel for each type of generated energy). Thermal diagram The station establishes the relationship between the main and auxiliary units that take part in the generation of electricity and heat supplied to external consumers.

Fundamentally, the thermal design of a new type of power plant (power unit) is developed on the basis of existing theoretical studies, operating experience of existing power plants, new technical proposals and the results of technical and economic calculations.

Drawing up a basic thermal diagram of a thermal power plant has a number of features. At thermal power plants with industrial and heating loads, heating turbine units of two or three different types (PT, R, T) are technologically interconnected. Thus, the common lines are the industrial steam extraction lines of the PT and R turbines, the return condensate lines of external consumers, additional water, and make-up water of the heating network. However, network heating installations are usually carried out individually for each T or PT type turbine unit. At such a complex thermal power plant with different types of turbine units, the thermal circuit fundamentally includes one turbine unit of each type. The basic thermal diagram of such a thermal power plant includes circuits for the supply of steam and hot water, as well as regenerative heating of water for each turbine unit, preparation of make-up and additional water.

For thermal power plants with industrial and heating loads and different types of heating turbine units (PT, R, T), technologically interconnected (lines of industrial steam extraction, heating of additional and make-up water and return condensate), the basic thermal diagram is drawn up as a single diagram consisting of connected diagrams of different types of units.

The schematic diagram of heat supply includes:

1 turbine PT-60/75-130/13;

1 turbine T-50/60-130;

3 steam boilers type E-320-140;

2 peak water heating boilers KV-TK-100;

Regenerative feedwater heaters;

Main pumps (condensate, feed, network);

Deaerators of feed and network water;

Make-up units for the main cycle of the station and the heating network;

Unit for supplying heat to an external consumer.

Steam boilers series "E" are designed to produce saturated steam consumed by enterprises of all industries for technological, heating and domestic needs. Boiler E-320-100 with natural water circulation. Natural circulation is formed in closed loop due to the difference in the density of the mixture in the lowering and rising pipes.

Steam is supplied to the middle part of the turbine through two stop valves and four control valves. One heater is connected to the turbine high pressure(HPH), fed by steam from the extractions and the outlet pipe. The turbine unit also has a deaerator.

Turbine T - 50/60-130.

T - turbine with heating extraction;

50 - rated power of the turbine, MW;

60 - maximum power turbines (with extraction switched off), MW;

130 - steam pressure in front of the turbine, atm. (13.0 MPa).

The heating steam turbine T-50/60-130 is designed to drive an electric generator and has two district heating outlets for releasing heat for heating.

The heat treatment plant of the T-type turbine has three stages of heating the network water:

Cogeneration heater for bottom steam extraction (heating up to 85 O C);

Cogeneration heater for upper steam extraction (up to 140 O C);

Peak hot water boiler (up to 180 - 200 O C).

Sequence of the technological process: steam generated in the boilers is sent through steam lines to the cylinders of the turbines.

Steam in the turbine PT - 60/75-130/13 from the extractions enters the high-pressure heater (HPH) to heat the feed water and the main waste water, for the needs of process consumers.

The steam in the T-50/60-130 turbine, having worked at all stages of the HPC, enters the LPC, after which it enters the condenser. In the condenser, the exhaust steam is condensed due to the heat transferred to the cooling water, which has its own circulation circuit, then, using condensate pumps, the main condensate is sent to the regeneration system. This system includes 2 PS and a deaerator. The regeneration system is designed to heat the feed water at the entrance to the boiler to a certain temperature. This temperature has a fixed value and is indicated in the turbine passport.

The heaters are surface heat exchangers; the water in them is heated by the heat of the steam taken from the turbine. Drainage from the heaters is discharged either into the previous heater or using drainage pumps to the mixing point. After the main condensate has passed 2 PS, it enters the deaerator, the main purpose of which is not to heat the water, but to clean it of oxygen, which causes corrosion of the metals of pipelines, screen pipes, superheater pipes and other equipment. At the same time, in order for the deaeration process to occur in principle in deaerators, the saturation temperature must be maintained.

The main condensate, having undergone 2 PS and the process of purification from aggressive gases, is sent to feed pumps, which create the necessary pressure, and is sent to the HPH group, consisting of two heaters. Water that has strictly defined parameters and meets the standards chemical control, called feed water and goes to the boiler.

Feeding pumps. The water supply to the boilers must be reliable. If the water level drops below acceptable limits, the boiling pipes may become exposed and overheat, which in turn may lead to an explosion of the boiler. Boilers with a pressure above 0.07 MPa and a steam output of 2 t/h and above must have automatic power regulators.

To power the boilers, at least two pumps are installed, of which one must be electrically driven and the other must be steam driven. The capacity of one electrically driven pump must be at least 110% of the rated capacity of all working boilers. When installing several pumps with electric drives, their total performance must also be at least 110%.

Condensate pump. The performance of the condensate pump is equal to the hourly consumption of condensate from the process consumer. To this consumption should be added the consumption of condensate from the network heating heater, since in cases of increased hardness, the condensate is discharged into the condensate tank for the needs of the domestic hot water supply.

Network pump for heating and ventilation systems. This pump serves to circulate water in the heating network. It is selected according to the flow of network water based on the thermal scheme. Network pumps are installed on the return line of the heating network, where the temperature of the network water does not exceed 70 0 C.

The pressure developed by the network pump is selected depending on the required pressure from the consumer and the network resistance with a 10% margin.

Make-up pump. Designed to replenish water leaks from the heating system, the amount of water required to cover the leaks is determined in the calculation of the thermal circuit. The capacity of the make-up pumps is selected equal to twice the amount of water received to replenish possible emergency make-up.

The required pressure of the make-up pumps is determined by the water pressure in the return line and the resistance of the pipelines and fittings in the make-up line; the number of make-up pumps must be at least 2, one of which is a reserve one.

ROU are designed to reduce the pressure and temperature of steam in order to:

Providing heat supply systems with backup steam (directly from steam boilers) in the event of shutdown of heating steam turbines or the appearance of peak heat loads;

Adjustment of steam parameters from turbine or backpressure turbine extractions to the values ​​required by the consumer.

Heat consumers in heat supply systems are heating, ventilation and air conditioning systems, hot water supply (DHW) systems, thermal and power technological units.

In heating systems of residential and public buildings Hot water is mainly used as a coolant at the maximum temperature at the entrance to the heating device t = 105? 95 0 C. For nurseries and kindergartens, hospitals t = 85 0 C. For most production premises, as well as staircases t = 150 0 C. Coolant temperature limitation

t = 95?105 0 C for premises of residential and public buildings is due to the decomposition and dry sublimation of organic dust (at a temperature of 65? 70 0 C, more intense at t ? 80 0 C). By sanitary standards the surface temperature of the heating device should not exceed 95 0 C (t op? 95 0 C).

The water temperature for hot water supply should be within 60–70 0 C. The design temperature t 1 of network water in the supply pipeline is taken equal to 130 0 C or 150 0 C. According to technical and economic conditions, it is allowed to take t 1 higher (up to 200 0 C) or lower (up to 95 0 C).

In most cases, two-pipe water systems are used to supply cities with heat. The heating network consists of two parallel pipelines: supply and return. Hot water is supplied from the station to subscribers through the supply pipeline, and cooled water is returned to the station through the return pipeline. The predominant use of two-pipe systems in cities is explained by the fact that they are suitable for supplying heat to homogeneous consumers, that is, heating and ventilation systems operating under the same modes. In this case, all supplied thermal energy has the same potential (water of the same temperature at a given outside air temperature).

Water heating systems are divided into two groups according to the method of connecting hot water supply systems: closed (closed) and open (open). IN closed systems The water circulating in the heating network is used only as a heating medium, that is, as a coolant, and is not taken from the network. In open systems, water circulating through heating networks is partially or completely collected from hot water consumers. The minimum number of pipelines for an open system is one, for a closed system two.

Schemes for connecting heating and ventilation systems to heating networks can be dependent and independent.

At dependent circuit water from heating networks directly enters the heating devices of heating and ventilation systems.

With an independent scheme, water from heating networks reaches only the heating points of local systems and does not enter heating devices, but in specially designed heaters it heats the water circulating in the heating and ventilation systems and returns through the return heat pipeline to the heat supply source.

The equipment of a heating point with a dependent circuit is much simpler and cheaper than with an independent one. However, a significant drawback of dependent circuits, consisting in the transfer of pressure from the heating network to local systems and heating devices, in some cases forces the use of independent connection circuits. They are used in cases where the pressure level in the return heat pipe of the heating network exceeds the permissible level for heating devices local systems ( cast iron radiators withstand a maximum excess pressure of 0.6 MPa) and in a number of other cases.

In most cases heating systems Residential and public buildings are connected to water heating networks in a dependent circuit with a mixing device. This is explained by the fact that according to SNiP 2-04.05-91 for residential buildings, dormitories, schools, clinics, museums and other buildings, the maximum (maximum) coolant temperature is 95 0 C, while maximum temperature water in the supply line is assumed in most cases to be equal to 150 0 C, and there is a tendency to further increase water temperature in the network.

The main advantages and disadvantages of closed systems.

Advantages:

Hydraulic isolation tap water, entering hot water supply installations, from water circulating in the heating network. This ensures a stable quality of hot water supplied to hot water supply units, identical to the quality of tap water. The water supplied to hot water supply installations is not contaminated by sludge, silt, or corrosive deposits deposited in the network and heating devices;

Extremely simple sanitary control of the hot water supply system due to the short path of tap water from the entrance to the building to the tap;

Simple control of the tightness of the heating system, which is carried out based on the make-up flow.

The disadvantages of closed systems are:

Complication of equipment and operation of hot water supply user inputs due to the installation of water-to-water heaters;

Corrosion in hot water supply systems of buildings, since they receive heated tap water containing oxygen (lack of deaeration);

Scale formation in hot water heaters on thermal inputs with increased hardness of tap water.

To ensure high quality heat supply, as well as economical modes of heat generation at thermal power plants or in boiler houses and its transportation through heating networks, the appropriate control method is selected.

Depending on the point of implementation of regulation, central, group, local and individual regulation are distinguished. Central regulation is carried out at the thermal power plant or in the boiler room; group - at group thermal substations (GTS); local - at local thermal substations (MTS), often called subscriber inputs; individual - directly on heat-consuming devices. To ensure high efficiency of heat supply, combined regulation should be used, which should be a rational combination of at least three stages of regulation - central, group or local and individual.

Effective regulation can only be achieved with appropriate systems automatic regulation(SAR), and not manually, as was the case in the initial period of development district heating.

In water district heating systems (DHS), it is fundamentally possible to use three central control methods:

Qualitative, which consists in regulating heat supply by changing the temperature of the coolant at the inlet to the device while maintaining constant quantity(flow) of coolant supplied to the regulated installation;

Quantitative, which consists in regulating heat supply by changing the coolant flow rate at a constant temperature at the inlet to the controlled installation;

Qualitative-quantitative, which consists in regulating heat supply by simultaneously changing the flow rate and temperature of the coolant.

When automating subscriber inputs, the main application in cities was central qualitative regulation, supplemented at GTP or MTP by quantitative regulation or regulation by passes.

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Introduction

The course project consists of two parts: calculation of the basic thermal diagram of a steam turbine unit (STU) (section “Heat supply sources for enterprises”) and calculation of a water heat supply system (section “Heat supply systems for enterprises”).

Approximately 80% of all electricity generated in the world comes from steam turbine plants, in which water steam is used as a working fluid, performing a regenerative cycle, i.e., a thermal cycle with steam extraction for regenerative heating of feed water in mixing or surface heaters. A steam turbine is used to convert the thermal energy of steam into mechanical energy (rotor rotation energy) and then into electrical energy. The efficiency of steam turbines depends on the initial and final steam parameters, as well as the type of turbines used. In accordance with the type of process load at the steam turbine unit, the following turbines are used:

condensing without controlled steam extraction (K-6-35);

condensation with district heating controlled steam extraction (T-6-35);

condensing with industrial controlled steam extraction (P-6-35/5);

condensing with two types of controlled steam extraction - production and heating (PT-50-130/7);

with back pressure (R-12-90/13).

The thermal energy generated by the PTU is transferred to various (industrial and non-industrial) consumers using heating networks. Through central heating points(CHP) heat is distributed for heating, ventilation and hot water supply. The main task of heating is to maintain the internal temperature of the room at a given level. To do this, it is necessary to maintain a balance between heat losses and heat gains.

There are several schemes for connecting hot water supply consumers to heating networks: dependent and independent, parallel and sequential, two-stage sequential and mixed. The choice of connection scheme depends on the specific conditions characteristic of a given area and is determined by several factors.

Calculation of the thermal circuit of the STU CHPP

Description of the thermal circuit of an industrial power plant

The basic thermal diagram of a thermal power plant (Appendix A) shows the technological connection of all the main elements of the station and their role in the technological process of generating heat and electrical energy, determines the direction of the main flows of steam, condensate, feed water, as well as their parameters.

Typically, the elements of a thermal circuit are placed on a drawing in a certain sequence. As a rule, in the upper left corner there is a steam generator (SG), which has the highest operating parameters. The remaining elements are arranged clockwise in order of decreasing and then increasing parameters of the main work flow. Consequently, the steam from the steam generator (first phase) is directed through the high-pressure pipeline to the high-pressure cylinder (HPC) of the turbine. Part of the steam through the first, second and third selections in the cylinder is sent for regenerative heating to the high-pressure heaters PVD1-PVD3 and the deaerator. From the last HPC selection, one part of the steam (calculated) goes to production needs (), the second goes to the low pressure cylinder (LPC) of the turbine. It has four selections, through which a smaller part of the steam is distributed to low-pressure heaters PND4-PND7; from the sixth and seventh selections, a significant part of the steam enters the network heaters SP1, SP2 to maintain the temperature schedule in the heating networks. The remainder of the steam, having passed through the last stage of the LPC, is sent to the condenser.

The capacitor is a cylindrical body, inside of which there are brass tubes. Cooling water flows through them, entering the condenser usually at a temperature of 10-15C. Steam flows around these tubes from top to bottom, cools, condenses and collects in the lower part of the housing.

With the help of a condensate pump (CP), the condensate passes through an ejector (EZ), where a deep vacuum is maintained, then through a stuffing box heater (SP) it is sent to the PND7-PND4 heaters, in which the temperature and pressure of the working flow increases.

After multi-stage heating, the condensate enters the active part deaerator columns, where it is mixed with make-up water. The water entering the deaeration is introduced through pipes into a mixing device located in the upper part of the column. Flowing down, it is dispersed in the mixing device, which facilitates the release of gases when it boils. From below, towards the water, steam is supplied from the turbine cylinder outlet through the nozzles of the deaeration column. The gas-saturated steam-air mixture is sucked off through a pipe at the top of the column.

Deaerated water enters the deaerator accumulator, the capacity of which serves as a reserve and is used in emergency situations. From here, the prepared water flows by gravity into the feed pump (PN), which pumps it into the PVD3-PVD1 heaters. After three-stage heating, the working flow is sent to the SG boiler.

In practice, there are three methods for calculating the thermal circuit:

in shares of selections;

based on a predetermined steam flow rate to the turbine with subsequent refinement;

according to a given passage of steam into the condenser.

In these instructions, the thermal circuit is calculated using a predetermined steam flow to the turbine for only one mode, corresponding to the highest power.

Calculation of the thermal diagram of the heat supply source is one of the main, most important stages design. Target- determination of quantitative and parametric characteristics of the main flows of steam and water, selection based on these characteristics of the main and auxiliary equipment, determination of pipeline diameters, turbine power and water treatment productivity. To perform the calculation, make up basic design diagram, containing the following elements:

1. Conventional image of the main and auxiliary equipment;

2. Single-line image of communications;

3. Equipment operating parameters (pressure, temperature, heat content);

4. Environmental flow rates according to design modes.

The thermal scheme is considered for four characteristic modes. Each of them is distinguished by a certain value of external temperature, which corresponds to the thermal loads of heating, ventilation and hot water supply.

First mode- maximum winter, corresponds to the calculated outside temperature air for heating design. Required to check the provision of basic equipment below thermal loads.

Second mode - corresponds to the average temperature of the coldest month. In this mode, the maximum long-term heat output for the technology, the average heat output for heating for the coldest month and the average hourly DHW load should be ensured, subject to failure of the most powerful steam or water heating boiler. Necessary for selecting the number of boiler units.

Third mode– mid-winter, corresponds to the average temperature for heating season. Necessary for calculating average annual technical and economic indicators and selecting the heating mode of operation of the main equipment.

Fourth mode– mid-summer, characterized by the absence of thermal loads of heating and ventilation. Necessary for calculating average annual technical and economic indicators and selecting the heating mode of operation of the main equipment.

Thermal loads of technological consumers in general case are not a function of external temperatures, therefore the connection of the indicated loads and the regime determined by external temperatures is to a certain extent conditional. However, in order to take into account all heat loads provided from the heat supply source, process loads are determined according to the above modes based on data on heat consumption for specific types of industrial consumption. In the absence of such data, the technological load is assumed to be equal to its maximum value in the first, second and third modes, and in the fourth it is reduced by 20-30%.

The calculation of the thermal scheme is performed sequentially for each of the four modes based on a free table of thermal loads and design schemes. Since the calculation of the thermal circuit of a thermal power plant and a boiler house has many common elements, we will consider the calculation methodology using the example of an industrial heating thermal power plant with the necessary values ​​​​related to boiler houses.

It is convenient to divide the calculation into several stages:

1. Definition of initial data.

At this stage the following operations are performed:

a) clarification of thermal and electrical loads;

b) selection of the type of source and the approximate composition of the main equipment and its parameters;

c) determining the percentage of water blown out of the boilers depending on the quality of the source water and its chemical purification scheme (usually 1.5-5%);

d) determination of the initial temperature raw water(usually in winter - 5 0 C, in summer - 10 ° C);

e) determination of the temperature of raw water used for chemical treatment (usually 20-40°C);

f) determination of the percentage of steam and water losses within the source circuit (usually 1.5-2% of the total coolant flow, excluding losses from non-returnable production condensate);

g) type of coolant for heating air in heaters, boilers (steam, hot water);

h) parameters of steam supplied to fuel oil farm(usually 0.9-1.2 MPa; 250-300 °C);

i) determination of the network water temperature graph.

2. Determination of steam and heat consumption at design points of the circuit.

The calculation of the thermal balances of the circuit is usually carried out in the given sequence.

Equation heat balance heating plant: Q ty = Q ov + Q hot water, where

Q ov - heating and ventilation load in this mode, GJ/h;

Network water consumption for closed heating systems:

G St = , where

t ps, t os - temperature of forward and return network water, 0 C;

t in - return water temperature of ventilation consumers, °C.

Amount of make-up water for closed systems equal to the number of losses: G sub = G losses; d For open systems: G sub = G hot water + G losses.

Heating network leakage, according to standards, is assumed to be equal to 0.5% of the volume of water in heating network pipelines, taking into account local heating and ventilation systems.

The amount of heat introduced into the system with make-up water is Q sub = G sub ∙t sub, where t sub is usually taken equal to 70 0 C, that is, the minimum value of the direct water temperature, regardless of the outside air temperature.

Based on calculations of the thermal scheme, summary tables of heat and material balance are compiled for four design modes. In addition, it should be noted that in the second mode, determined by the temperature of the coldest month, the balance is achieved without one of the most powerful boilers. This is done to check the possibility of providing loads in the event of an emergency or repair failure of the boiler.

Department of Heat Engineering and Hydraulics

Coursework

“Calculation of thermal circuit of thermal power plant”

Educational and methodological manual

Specialties: 250200 – chemical technology of inorganic substances, 100700 – industrial heat and power engineering

Cherepovets

Considered at a meeting of the Department of Heat Engineering and Hydraulics, minutes No. 3 dated November 11, 1998.

Approved by the editorial and publishing commission of the Engineering and Technical Institute of ChSU, protocol No. dated

Compiled by: E. L. Nikonova

Reviewers: N. N. Sinitsyn – Ph.D. tech. Sciences, Associate Professor (CSU);

N. S. Grigoriev - Ph.D. tech. Sciences, Associate Professor (CSU)

Scientific editor:

© Cherepovets State University, 2002

INTRODUCTION

All industrial enterprises need heat and electricity at the same time. A complex of installations and units that generate and transport heat and electricity to consumers is called the heat and power supply system of an enterprise.

Unlike electricity, heat (especially with steam as a coolant) cannot be economically supplied over very long distances, so each enterprise requires its own heat source with the required parameters. Such sources are combined heat and power plants (CHPs), which produce combined heat and electricity.

CHP plants provide greater fuel savings compared to the separate production of thermal and electrical energy.

This educational and methodological manual is intended for students of specialties 250200, 100700, who must have the skills to competently manage the design and operation of modern production, which is a set of technological and thermal processes and corresponding technological and thermal power equipment.

The educational manual presents the following sections: “Description of the basic thermal diagram of a thermal power plant”, “Drawing up a thermal diagram of a thermal power plant”, “The process of steam expansion in a turbine”, “Calculation of the thermal diagram of a thermal power plant”, “Calculation of a network heating installation”, “Determination of equivalent fuel consumption ”, “Construction of a heating cycle in a T-S-diagram”. An example of calculation is given. The manual contains all the reference material necessary to carry out the calculations.

The manual is devoted to the calculation of the circuit of a thermal power plant operating on a heating cycle with heat recovery, and is aimed at consolidating theoretical knowledge among students, familiarizing them with the equipment and technological processes occurring at a thermal power plant, and methods of thermotechnical calculations of thermal power plant equipment.

1. Description of the basic thermal diagram of a steam power plant

Thermal power station(TES) is a complex of equipment and devices, the purpose of which is to convert the energy of a natural source into electrical and thermal energy.

Steam turbine thermal power plants use water vapor as working heat, which performs a regenerative cycle, i.e. thermal power cycle with steam extraction from the turbine for regenerative heating of feedwater in mixing or surface regenerative heat exchangers.

Schematic thermal diagram shows the connection of the main technological equipment in the process of generating heat and electricity according to a given cycle.

The schematic diagram of the thermal power plant is shown in Fig. 1. Fuel is burned in the furnace of a steam generator (SG), while the feed water is heated, boils and evaporates, forming saturated water vapor. The steam is supplied to a superheater (SS), in which it is heated at constant pressure to a temperature T 0 .

Superheated steam with parameters R 0 and T 0 enters the I and II stages (compartments) of the turbine, where it does work, generating energy in the electric generator (EG). The exhaust steam enters the barometric condenser (BC). Here the steam is condensed and sent to the first low-pressure heater (LPH 1).

In order to increase the thermodynamic efficiency of the cycle by reducing heat removal to the environment by reducing the flow of steam entering the condenser, regenerative heating of feed water is used. Regenerative feedwater heating- this is the heating of condensate and additional water sent to the steam generator with steam from turbine extractions. Depending on the type of station, steam and feedwater parameters, a steam turbine can have a different number of steam extractions (from 2 to 9), one or two of these extractions are adjustable, the steam from which is used for heat supply needs. Regenerative heating is carried out in several heaters located in series. The main condition for the normal operation of these installations is that the feed water pressure is higher than the heating steam pressure (to avoid boiling of the heated medium). Regenerative heating of feedwater at thermal power plants to optimal temperature provides significant savings in fuel and reduced costs.

Regenerative heaters are mainly made vertical.

The regenerative heating circuit also includes a mixing-type heater - a deaerator. It not only heats the feed water (by mixing), but also removes aggressive gases from the water.

The heated feed water is supplied to the steam generator, where it acquires a high energy potential, turns into steam and enters the steam turbine. Part of the steam passes through several stages of the turbine, is taken from it at increased parameters and is sent for regenerative heating. The rest of the steam passes through all stages of the turbine. The waste steam of this stream, which has a low energy potential, enters the condenser. The latent heat of vaporization is lost. The latent heat of vaporization of steam streams taken for regeneration is returned to the cycle with feed water. The heat of the steam flow selected for heat supply is transferred to the network water.

Network water for heat supply needs is produced in a network or peak heater.

The main network heaters are fed with steam from a controlled extraction.

Peak heaters are included in the circuit during periods of peak heating loads (for example, when the outside air temperature drops significantly) and are powered by “hot” steam from a steam generator passing through a reduction-cooling unit, which reduces the parameters of “hot” steam (pressure and temperature) to the required quantities

All condensate flows from the condenser, network water heaters, high-pressure heaters, low-pressure heaters, as well as the addition of chemically purified water are drained into the deaerator.

The condensate in the HDPE has higher parameters than the medium in the deaerator, and the condensate in HDPE 1 has higher parameters than the steam in HDPE 2. They can be used as a heating medium. Due to the pressure difference, these condensate flows are directed to HDPE 1 through condensate traps (they pass condensate, but do not allow steam to pass through).