RU2566249C1 - Method of heat recycling of thermal power plant - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention can be used in thermal power plants (TPP). Additionally, the recycling of low-grade heat of the oil supply system of bearings of the steam turbine is carried out, and the recycling of low-grade heat of the oil supply system of bearings of the steam turbine and the recycling of low-grade heat of steam of the heating outfeed from the steam turbine is carried out by means of a heat engine with a closed circuit of circulation, operating in the organic Rankine cycle, in which the coolant is used as low boiling working body circulating in a closed circuit, at that it is compressed in the condensate pump of the heat engine, heated in the heat-exchanger-recuperator of the heat engine, heated in the oil cooler, heated and vaporized in the lower network heater of the steam turbine, superheated in the upper network preheater of the steam turbine, expanded in a turbo-expander of the heat engine, its temperature is reduced in the heat exchanger-recuperator of the heat engine and condensed in the heat exchanger-condenser of the heat engine.

EFFECT: invention enables to recycle low-grade heat of the oil supply system of bearings of the steam turbine and the low-grade heat of steam of heating outfeeds from the steam turbine for additional production of electric energy, which is carried out by sequential heating, respectively, in the oil cooler and the network heaters of low boiling working body of the heat engine with a closed circuit of circulation, working on organic Rankine cycle.

3 cl, 1 dwg

Description

The invention relates to the field of energy and can be used at thermal power plants (TPPs) for the utilization of low-grade heat from the oil supply system of bearings of a steam turbine and the utilization of low-grade heat from steam of heating extracts from a steam turbine for additional generation of electric energy.

An analogue is the method of operation of a thermal power plant, in which the entire return flow of network water returned from consumers is heated by steam of turbine withdrawals in the lower and upper network heaters, as well as in the condenser of the heat pump installation with heat removed from the return network water in the evaporator of the heat pump installation, after which they are sent to consumers, while the entire flow of network water is sequentially heated in the lower network heater, the condenser of the heat pump installation and the upper network heater atelier (patent RU No. 2275512, IPC F01K 17/02, 04/27/2006).

The prototype is the method of operation of a thermal power plant containing a cogeneration turbine with heating steam extraction, supply and return pipelines of the heating network, network heaters connected via a heated medium between the supply and return pipelines of the heating network and connected via heating medium to the heating selection, heat pump installation with an evaporator included in the return pipe of the heating system, and a condenser, while the condenser of the heat pump installation is included in the supply pipe of the heating system after heaters, as well as a steam turbine bearing oil supply system, comprising a drain pipe, an oil tank, an oil pump and an oil cooler connected in series through a heating medium, the outlet of which is connected to a pressure pipe through a heated medium (patent RU No. 2269014, IPC F01K 17/02, 01/27/2006 )

In the known method, the network water returned from the consumers through the return pipe of the heating network is supplied by the network pump to the evaporator of the heat pump installation, where it transfers part of the heat to the coolant of the heat pump installation and is cooled, then the network water is supplied to the network heaters, where it is heated by steam from the turbine heating taps. Before being supplied to consumers, the network water is additionally heated in the condenser of the heat pump installation due to the heat of the refrigerant circulating in the circuit of the heat pump installation. Due to the sequential inclusion of the evaporator of the heat pump installation in the return pipe of the heating system to the network heaters, and the condenser in the supply pipe of the heating system after the network heaters, maximum cooling of the return network water is achieved. In a steam turbine, an oil supply system for bearings of a steam turbine with an oil cooler is used.

Thus, in the known method of operating a thermal power plant, the exhaust steam flows from the steam turbine into the condenser steam space, condenses on the surface of the condenser tubes, the condensate is sent to the regeneration system using the condensate pump of the steam turbine condenser, and the steam of the heating parameters from the steam turbine take-off flows to the vapor space of the upper and lower network heaters condenses on the surface of the heated tubes of the network heaters, inside of which x coolant flows, wherein the vapor condensation heating selections performed utilization of low-potential heat from the vapor heating heats steam turbine using coolant, which is used in a steam turbine system of a steam turbine bearing oil supply oil cooler.

The main disadvantage of the analogue and prototype is that the utilization of low-grade heat of the steam from the heating taps from the steam turbine is carried out in order to generate additional thermal energy, and not for additional generation of electric energy.

In addition, the disadvantage of the analogue and prototype is the relatively low efficiency of TPPs for generating electric energy, due to the cost of electric power to drive the heat pump installation, and also due to the lack of utilization of low-grade heat of the oil supply system of the steam turbine bearings for additional power generation.

The objective of the invention is to increase the efficiency of TPPs due to the utilization of low potential heat of steam from heating steam from a steam turbine and the utilization of low potential heat of the oil supply system of bearings of a steam turbine for additional generation of electric energy.

The technical result is achieved by the fact that in the method of operation of a thermal power plant, in which the exhaust steam from the steam turbine to the condenser steam space is condensed on the surface of the condenser tubes, the condensate is sent to the regeneration system using the condenser pump of the condenser of the steam turbine, and the steam of the heating parameters from steam turbine sampling enters the steam space of the upper and lower network heaters, condenses on the surface of the heated network tubes x heaters, inside which coolant flows, while the condensation of the heating steam is used to utilize the low-grade heat of the steam from the heating steam from the steam turbine using coolant, and the steam turbine uses an oil supply system for bearings of a steam turbine with an oil cooler, according to the present invention, recycling low-potential heat of the oil supply system of bearings of a steam turbine, while recycling low The specific heat of the oil supply system of the steam turbine bearings and the low potential heat of the steam from the heating steam from the steam turbine are utilized using a closed-loop heat engine operating on the organic Rankine cycle, in which a low-boiling working fluid circulating in a closed loop is used as coolant, this is compressed in a heat engine condensate pump, heated in a heat engine heat exchanger-recuperator, heated in oil aditele heated and vaporized in the lower network preheater steam turbine is superheated in the upper network preheater steam turbines is expanded in an expansion turbine of the heat engine, reduce its temperature in the heat exchanger-recuperator heat engine and condensed in exchanger-condenser heat engine.

As a heat exchanger-condenser of a heat engine, either an air-cooled condenser, or a water-cooled condenser, or an air-cooled and water-cooled condenser are used.

As a low-boiling working fluid, liquefied propane C ₃ H _{8 is used} .

Thus, the technical result is achieved by utilizing the low potential heat of the oil supply system of the steam turbine bearings and utilizing the low potential heat of the steam from the heating steam extraction from the steam turbine to additionally generate electric energy, which is carried out by sequential heating in the oil cooler and network heaters of the low boiling medium (liquefied propane C ₃ H ₈₎ of the heat engine with closed-loop circulation operation in the organic iklu Rankine.

The invention is illustrated in the drawing, which shows a thermal power plant having a heat engine with a heat exchanger-condenser, a heat exchanger-recuperator and network heaters.

In the drawing, the numbers indicate:

1 - steam turbine,

2 - condenser of a steam turbine,

3 - condensate pump condenser of a steam turbine,

4 - the main generator

5 - heat engine with a closed circuit,

6 - turboexpander,

7 - electric generator,

8 - heat exchanger-condenser,

9 - condensate pump,

10 - upper network heater,

11 - lower network heater,

12 - oil supply system for bearings of a steam turbine,

13 - drain pipe

14 - oil tank

15 - oil pump,

16 - oil cooler

17 - pressure pipe

18 - heat exchanger-recuperator.

The thermal power plant includes a series-connected steam turbine 1, a steam turbine condenser 2 and a condenser pump 3 of a steam turbine condenser, a main electric generator 4 connected to a steam turbine 1, which is connected via heating medium to the upper 10 and lower 11 network heaters, which are interconnected on a heated medium, as well as a system 12 of oil supply for bearings of a steam turbine 1, comprising a drain pipe 13, an oil tank 14, an oil pump 15 and oil, connected in series through a heating medium cooler 16, the output of which is connected via a heated medium to a pressure pipe 17.

A heat engine 5 with a closed circulation loop, operating according to the organic Rankine cycle, has been introduced into the thermal power station.

The closed circuit of the circulation of the heat engine 5 is made in the form of a circuit with a low boiling fluid containing a turboexpander 6 with an electric generator 7, a heat exchanger-recuperator 18, a heat exchanger-condenser 8 and a condensate pump 9, and the output of the condensate pump 9 is connected via a heated medium to the input of the heat exchanger-recuperator 18, which is connected via a heated medium to the input of the oil cooler 16, the output of the oil cooler 16 is connected via a heated medium to the input of the lower network heater 11, and the output of the upper network is heated For 10, it is connected via a heated medium to the inlet of a turboexpander 6, the output of which is connected via a heating medium to a heat exchanger-recuperator 18, the output of a heat exchanger-recuperator 18 is connected via a heating medium to a heat exchanger-condenser 8, the output of which is connected via a heated medium to the inlet of a condensate pump 9, forming a closed cooling circuit.

The method of operation of a thermal power plant is as follows.

The exhaust steam comes from the steam turbine 1 into the steam space of the condenser 2, condenses on the surface of the condenser tubes, the condensate is sent to the regeneration system using the condensate pump 3 of the condenser of the steam turbine, and the steam of heating parameters from the steam turbine take-offs 1 enters the steam space of the upper 10 and lower 11 network heaters, condenses on the surface of the heated tubes of the network heaters 10 and 11, inside which coolant flows, while pa heating selections performed utilization of low-potential heat from the vapor heating heats the steam turbine 1 by means of a cooling fluid, wherein in the steam turbine 1 uses the oil supply system 12 of the steam turbine bearing oil cooler 16.

The difference of the proposed method is that they additionally utilize the low-grade heat of the oil supply system 12 of the bearings of the steam turbine 1, while utilizing the low-grade heat of the oil supply system 12 of the bearings of the steam turbine 1 and utilize the low-grade heat of the steam from the heating taps from the steam turbine 1 using a heat engine 5 s closed loop operating on the organic Rankine cycle, in which n is used as a coolant a boiling working fluid circulating in a closed circuit, while it is compressed in the condensate pump 9 of the heat engine, heated in the heat exchanger-recuperator 18 of the heat engine, heated in the oil cooler 16, heated and evaporated in the lower network heater 11 of the steam turbine, overheated in the upper network heater 10 of a steam turbine, expand in a turbine expander 6 of a heat engine, lower its temperature in a heat exchanger-recuperator 18 of a heat engine and condense in a heat exchanger-condenser 8 of a heat engine Igater.

As the heat exchanger-condenser 8 of the heat engine, either an air-cooled condenser, or a water-cooled condenser, or an air and water-cooled condenser are used.

As a low-boiling working fluid, liquefied propane C ₃ H _{8 is used} .

Concrete example

The exhaust steam coming from the steam turbine 1 into the steam space of the condenser 2 is condensed on the surface of the condenser tubes. In this case, the condensate formed is sent via a condensate pump 3 of the steam turbine condenser to the regeneration system. The power of the steam turbine 1 is transmitted to the main generator 4 connected to one shaft.

The conversion of low-grade thermal energy from the oil supply system of bearings of the steam turbine 1 to 12 and low-grade thermal energy from the steam of the heating taps from the steam turbine 1 to mechanical and then to the electric one takes place in a closed loop of the heat engine 5 operating on the organic Rankine cycle.

Thus, the low-grade heat of the oil supply system 12 of the bearings of the steam turbine 1 is utilized and the low-grade heat of the steam from the heating taps from the steam turbine 1 is recovered by sequential heating of the low-boiling working fluid (liquefied propane C ₃ H ₈ ) in the oil cooler 16 and network heaters 11, 10, respectively engine 5 with a closed loop operating on the organic Rankine cycle.

The whole process begins with compression in a condensate pump 9 of liquefied propane C ₃ H ₈ , which is subsequently directed for heating first to a heat exchanger-recuperator 18, where superheated gaseous propane C ₃ H ₈ from the turbine expander 6 enters, and then to the oil cooler 16, where the heated the oil of the oil supply system 12 of the bearings of the steam turbine 1. The temperature of the heated oil in the oil cooler 16 can vary from 318.15 K to 348.15 K.

In the process of heat exchange of superheated gaseous propane C ₃ H ₈ with liquefied propane C ₃ H ₈ in heat exchanger-recuperator 18 and heat exchange of heated oil with liquefied propane C ₃ H ₈ in oil cooler 16, liquefied propane C ₃ H ₈ is heated within a critical temperature range from 300 K to 343.15 K at a supercritical pressure of 4.2512 MPa to 5.7 MPa, and then it is sent for heating and evaporation to the lower mains heater 11, where heating steam is taken from the steam turbine 1 at a temperature of about 380 K .

The steam coming from the heating selection of the steam turbine 1 into the steam space of the lower network heater 11 condenses on the surface of the heated tubes, inside which liquefied propane C ₃ H ₈ flows.

In the process of condensation of heating steam in the lower network heater 11 of the steam turbine 1, the liquefied propane C ₃ H ₈ is heated above a critical temperature of 369.89 K, at which it evaporates intensively, at a supercritical pressure of 4.2512 MPa to 5.7 MPa After the lower network heater 11, gaseous propane C ₃ H _{8 is} directed to overheat in the upper network heater 10, where the heating steam from the steam turbine 1 enters at a temperature of about 410 K.

The steam coming from the heating selection of the steam turbine 1 into the steam space of the upper network heater 10 condenses on the surface of the heated tubes, inside which gaseous propane C ₃ H ₈ flows.

In the process of condensation of heating selection steam in the upper network heater 10 of the steam turbine 1, gaseous propane C ₃ H ₈ overheats to a supercritical temperature of 369.89 K to 400 K at a supercritical pressure of 4.2512 MPa to 5.7 MPa, which is directed to expansion into a turboexpander 6.

The process is constructed in such a way that in the expander 6 does not condensate gaseous propane C ₃ H ₈ during the operation of the heat transfer. The power of the turboexpander 6 is transmitted to an electric generator 7 connected to one shaft. At the outlet of the turboexpander 6, gaseous propane C ₃ H ₈ having a superheated gas temperature of about 288 K is sent to a heat exchanger-recuperator 18 to reduce the temperature.

In the heat exchanger-recuperator 18 in the process of heat removal for heating liquefied propane C ₃ H _{8, the} load on the heat exchanger-condenser 8, made, for example, in the form of an air-cooled condenser, and the power consumption for driving air-cooled fans are reduced.

Further, as the temperature of gaseous propane C ₃ H ₈ decreases, it is liquefied in a heat exchanger-condenser 8 cooled by ambient air in the temperature range from 223.15 K to 283.15 K.

After the heat exchanger-condenser 8 in a liquefied state, propane C ₃ H _{8 is} sent for compression to the condensate pump 9 of the heat engine.

Further, the organic Rankine cycle based on a low-boiling working fluid is repeated.

Using the proposed method of operation of a thermal power plant will allow, in comparison with the prototype, to increase the efficiency of TPPs by utilizing the low-grade heat of the oil supply system of the steam turbine bearings and utilizing the low-grade heat of the steam from the heating taps from the steam turbine to additionally generate electric energy.

Claims (3)

      1. The method of heat recovery from a thermal power plant (TPP), including the supply of exhaust steam from a steam turbine to the steam space of the condenser to ensure its condensation on the surface of the condenser tubes, the condensate being sent to the regeneration system using the condensate pump of the condenser of the steam turbine, and the heating parameters steam from the steam turbine offsets, they are sent to the steam space of the upper and lower network heaters to ensure its condensation on the surface of the heated pipes ok network heaters, inside which coolant flows, while the condensation of the heating steam is used to utilize the low-grade heat of the heating steam from the steam turbine using coolant, and in the steam turbine use the oil supply system of bearings of a steam turbine with an oil cooler, characterized in that TPPs use a closed-loop heat engine operating on the organic Rankine cycle, in which, as a coolant, and use a low-boiling fluid circulating in a closed circuit, and additionally utilize the low-grade heat of the oil supply system of the steam turbine bearings, while utilizing the low-grade heat of the oil supply system of the steam turbine bearings and utilize the low-grade heat of the steam from the heating taps from the steam turbine by compressing the low-boiling fluid condensate pump of a heat engine, its sequential heating in a heat exchanger-recupe the heat engine ator and in the oil cooler, then the low-boiling working fluid is heated and evaporated in the lower network heater of the steam turbine, overheated in the upper network heater of the steam turbine, expanded in the turbine expander of the heat engine, its temperature is reduced in the heat engine heat exchanger-recuperator and condensed in the heat exchanger-condenser heat engine. 2. The method according to p. 1, characterized in that the air-cooled condenser or the water-cooled condenser, or the air and water-cooled condenser are used as the heat exchanger-condenser of the heat engine. 3. The method according to p. 1, characterized in that as a low-boiling working fluid use liquefied propane C ₃ H ₈ .

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