KR20180078038A - Waste heat recovery system using absorption heat pump - Google Patents

Abstract

The present invention relates to a waste heat recovery system using an absorption heat pump capable of effectively recovering heat from discharged steam of low temperature and pressure and easily controlling the entire system. The waste heat recovery system according to the present invention comprises: a heat pump having an evaporator, an absorber, a regenerator and a condenser; a first heat source unit for providing energy required for evaporating refrigerant of the heat pump; and a second heat source unit for providing energy required for separating an absorbent, which absorbed the refrigerant in the absorber, into the refrigerant and the absorbent. The first heat source part receives energy from steam discharged after a steam turbine is operated, and the second heat source unit receives energy from processed steam during operation of the steam turbine.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a waste heat recovery system using an absorption type heat pump,

The present invention relates to a waste heat recovery system using an absorption type heat pump.

Recovery of waste heat in power generation systems is very important. However, even though the exhaust vapors from steam turbines in the power generation system still have heat, recovery of heat is not easy due to low temperature and pressure. Since the steam turbine is heavily influenced by the pressure of the condenser used to condense the exhaust steam, direct use of the exhaust steam discharged from the steam turbine for waste heat recovery has many difficulties in terms of control.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a waste heat recovery system capable of efficiently recovering heat in exhaust steam of low temperature and pressure, .

In one example, a waste heat recovery system using an absorption heat pump comprises a heat pump having an evaporator, an absorber, a regenerator and a condenser, a first heat source for providing the energy required for the refrigerant in the evaporator to evaporate from the evaporator, And a second heat source for providing the energy required to separate the absorbent absorbing the refrigerant from the absorber into the refrigerant and the absorbent in the regenerator, And the second heat source is supplied with energy from the process steam added during the operation of the steam turbine.

According to the present invention, it is possible to efficiently recover the waste heat of the exhaust steam through the absorption type heat pump, to realize not only the heating but also the cooling, and indirectly transmit the heat of the exhaust steam to the heat pump, .

1 is a conceptual diagram conceptually showing a waste heat recovery system according to a first embodiment of the present invention.
2 is a conceptual view conceptually showing an absorption type heat pump applied to the waste heat recovery system of FIG.
3 is a conceptual view conceptually showing a waste heat recovery system according to a second embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the understanding why the present invention is not intended to be a complete disclosure.

Example 1

FIG. 1 is a conceptual view conceptually showing a waste heat recovery system according to Embodiment 1 of the present invention, and FIG. 2 is a conceptual view conceptually showing an absorption heat pump applied to the waste heat recovery system of FIG.

The waste heat recovery system according to the present embodiment is characterized in that the waste heat still retained by the low-temperature low-pressure discharge steam discharged after the operation of the steam turbine is recovered through the absorption type heat pump to increase the efficiency of the entire system. 1 and 2, the waste heat recovery system according to the present embodiment includes a heat pump 100, a first heat source unit 200, and a second heat source unit 300 do.

Heat pump

First, the heat pump 100 will be described with reference to FIG. The heat pump 100 applied to the waste heat recovery system according to the present embodiment is an absorption type heat pump and includes an evaporator 110, an absorber 120, a generator 130, and a condenser 140 Respectively.

The evaporator 110 is a device for evaporating the liquid refrigerant in a vapor phase. The liquid phase refrigerant is generated by condensing the vapor phase refrigerant in the condenser 140, which will be described later, while heating the heating water, and the liquid phase refrigerant thus generated is supplied to the evaporator 110. A first heat source 200, which will be described later, provides energy to the evaporator 110 to evaporate the liquid refrigerant. For example, the liquid refrigerant may be injected into the circulation flow passage 220 of the first heat source unit 200 for evaporation. Where the energy may be thermal energy. The following energies are also the same. And the refrigerant may be water (H ₂ O).

The absorber 120 is a device for absorbing gaseous refrigerant generated in the evaporator 110 into the absorbent. The absorbent absorbing the refrigerant is supplied to the regenerator 130. Here, the absorbent may be LiBr. However, the absorbent is not limited thereto, and may be appropriately selected depending on the kind of refrigerant, for example.

The regenerator 130 is a device for separating the absorbent absorbing the refrigerant into the refrigerant and the absorbent again. For this sort of separation, the second heat source unit 300, which will be described later, provides energy to the regenerator 130. The absorbent absorbing the refrigerant is heated by the second heat source unit 300 and separated into a gaseous refrigerant and a liquid absorbent. The gaseous refrigerant is supplied to the condenser 140, and the liquid refrigerant is supplied to the absorber 120 again.

The condenser 140 is a device for receiving the gaseous refrigerant generated by the regenerator 130 and heating the heating water or the like to be described later through the condensation of the refrigerant. In the case of this embodiment, the heating water is supplied to the condenser 140 and heated after the district heating. At this time, the heating water may pass through the absorber 120 before the condenser 140 as shown in FIG.

The heat pump 100 applied to this embodiment requires two heat sources as described above. One is required in the evaporator 110 and the other is required in the regenerator 130, which are implemented by the first heat source 200 and the second heat source 300.

The first heat source unit

The first heat source 200 receives energy from the exhaust steam discharged after the operation of the steam turbine 400. The main purpose of the steam turbine 400 is to produce electricity. Accordingly, the steam supplied to the steam turbine 400 consumes most energy from the steam turbine 400, and the steam discharged after the operation of the steam turbine 400 is generally in a low-temperature and low-pressure state. The pressure of the exhaust steam may be approximately 0.2 atmospheres (0.2 ATA). At such pressures, the exhaust vapors can be at a temperature of about 60 ° C. Due to this low pressure and temperature, there are generally many limitations in recovering waste heat directly from the exhaust vapors.

The waste heat recovery system according to the present embodiment employs an absorption type heat pump to solve such a limitation, and it is possible to efficiently recover the waste heat of the exhaust steam. In addition, since the heat of the exhaust steam is indirectly transferred to the heat pump through a working fluid to be described later, it is easy to control the system in comparison with the case where heat is directly recovered from the exhaust steam. The heat pump 100 can implement not only heating but also cooling as in the second embodiment described later.

More specifically, the first heat source unit 200 may include a heat exchanger 210 and a circulation channel 220, as shown in FIG. The heat exchanger 210 is a device for heat exchange between the exhaust steam and a working fluid to be described later. By such heat exchange, the working fluid can be heated. In the heat exchanger 210, the latent heat of condensation of the exhaust steam can be recovered. The circulation flow path 220 is a flow path for circulating the working fluid between the heat exchanger 210 and the evaporator 110.

The first heat source unit 200 of FIG. 1 can be explained by dividing the heating of the working fluid by the exhaust steam and the heating of the refrigerant by the working fluid.

First, the heating of the working fluid by the exhaust steam will be described with reference to FIG.

All of the exhaust vapors discharged after the operation of the steam turbine 400 can be supplied to the heat exchanger 210. Or only a portion of the exhaust vapors discharged after operation of the steam turbine 400 may be supplied to the heat exchanger 210 to reduce the size of the heat exchanger 210. For example, at the front end of the condenser 410 for condensing exhaust steam, as shown in FIG. 1, it may be provided to the heat exchanger 210 after bypassing some of the exhaust vapors supplied to the condenser 410 .

The condenser 410 is generally used to condense exhaust steam in a power generation system using a steam turbine 400. Therefore, when the waste heat recovery system is implemented so that some of the exhaust steam supplied to the condenser 410 is supplied to the heat exchanger 210, the waste heat recovery system according to the present embodiment can be applied to the conventional power generation system as it is .

Also, since the condenser 410 and the heat exchanger 210 share the condensation of the exhaust steam, the power consumed by the condenser 410 can be reduced. For example, when the condenser 410 is an air-cooled type using a fan, the consumption power of the fan for blowing can be reduced, and when the condenser 410 is a water-cooled type using seawater or the like, Power can be reduced. For reference, air-cooled condensers are generally applied to systems with low generating capacity, and in such systems it is easier to bypass some of the exhaust vapors supplied to the condenser.

The amount of the exhaust steam supplied to the condenser 410 and the amount of the exhaust steam supplied to the heat exchanger 210 can be appropriately adjusted by the control of the valve 411 and the valve 412 in Fig.

Next, the heating of the refrigerant by the working fluid will be described with reference to FIGS.

The working fluid in the circulating flow passage 220 is heated by the exhaust steam in the heat exchanger 210, and then the refrigerant is heated in the evaporator 110. These heating is achieved by heat exchange between the exhaust vapors and the working fluid, and heat exchange between the working fluid and the refrigerant. Here, the working fluid may be water. The circulation flow path 220 includes a first flow path 221 for supplying a working fluid to the condenser 140 side in the heat exchanger 210 and a second flow path 221 for supplying a working fluid to the heat exchanger 210 on the side of the condenser 140 And a second flow path 222 for the second flow path.

The second heat source unit

The second heat source unit 300 is supplied with energy from the process steam added during the operation of the steam turbine 400. A portion of the steam supplied to the steam turbine 400 may be extracted from the steam turbine 400 before most of the energy is consumed in the steam turbine 400. The steam, which is added steam, is in a state of high temperature and high pressure as compared with the exhaust steam. Therefore, as a heat source of the regenerator 130 requiring a higher temperature than the evaporator 110, the waste heat recovery system according to the present embodiment utilizes the process steam as shown in FIGS. 1 and 2. That is, the process steam added from the steam turbine 400 can be supplied to the regenerator 130 of the heat pump 100.

Collection of condensate (storage tank)

The above-mentioned vapors can be cooled and condensed after heat exchange. It is preferable in terms of management of the system that the condensed water generated by such condensation is stored in one tank and managed. The waste heat recovery system according to the present embodiment may include a storage tank 420 for storing condensed water.

The condensed water generated in the heat exchanger 210 can be supplied to the storage tank 420 by the condensation of the exhaust steam. Also, the condensed water generated in the second heat source unit 300 can be supplied to the storage tank 420 by the condensation of the process steam.

The condensed water stored in the storage tank 420 may be mixed with the condensate generated in the condenser 410. [ The condensed water in the storage tank 420 and the condensed water in the condenser 410 can be supplied to the deaerator (not shown) by being mixed together. The deaerator is a device for removing foreign substances in the condensed water by heating and evaporating the condensed water.

Heating of heating water

In the present embodiment, the heat pump 100 can heat the heating water of the district heating in the condenser 140. [ The condenser 140 can heat the heating water by condensing the refrigerant separated from the absorbent in the regenerator 130. More specifically, the heating water after district heating (heating water return) can be heated through the condenser 140, or through the absorber 120 and the condenser 140.

To heat the heating water to a higher temperature, the system according to this embodiment can utilize process steam. For example, as shown in FIG. 1, the process steam may be separated into a first stream and a second stream, wherein the first stream is used to provide energy to the second heat source unit 300 described above, The second stream may be used to provide energy to the third heat source 310. The third heat source unit 310 is a heat exchanger for reheating the heating water discharged from the condenser 140 again.

The first stream may be condensed after heat exchange and supplied to the storage tank 420 and the second stream may also be condensed and supplied to the storage tank 420 after heat exchange.

In the waste heat recovery system according to the present embodiment, the heating water after the district heating is primarily heated through the condenser 140 of the heat pump 100 and is secondarily heated through the third heat source unit 310 , The heating water can be heated to a temperature suitable for district heating.

The steam turbine 400 associated with the waste heat recovery system according to the present embodiment may be a steam turbine in a power generation system using a steam turbine or a steam turbine in a combined power generation system in which a steam turbine, have.

Example 2

The waste heat recovery system according to the second embodiment uses the absorption heat pump to heat the heating water for the district heating and also cools the cooling water for the district cooling. . 3 is a conceptual view conceptually showing a waste heat recovery system according to a second embodiment of the present invention.

The waste heat recovery system according to the present embodiment includes a first cooling water channel 231 and a second cooling water channel 232 as shown in FIG. The first cooling water channel 231 is a channel for supplying the cooling water (cooling water return) for the district cooling to the first channel 221 of the circulation channel 220. The second cooling water channel 232 is a channel for discharging the cooling water from the second channel 222 of the circulation channel 220. When the cooling water is supplied to the first cooling water flow path 231, the cooling water is taken away from the evaporator 110 of the heat pump 100 while passing through the first flow path 221 and the second flow path 222, . The cooling water thus cooled can be utilized again for the district cooling.

In the meantime, the waste heat recovery system according to the present embodiment is provided with both a heating flow path and a cooling flow path as shown in FIG. 3, and may further include valves for switching between them. More specifically, the system according to the present embodiment may further include first to fourth valves 241 to 244 and a control unit (not shown) for controlling the first to fourth valves 241 to 244 as shown in FIG.

The first valve 241 is provided in the first flow path 221 between the heat exchanger 210 and the connection point A, The connection point A is a point connecting the first flow path 221 and the first cooling water flow path 231. The second valve 242 is provided in the second flow path 222 between the heat exchanger 210 and the connection point B. The connection point B is a point connecting the second flow path 222 and the second cooling water flow path 232. The third valve 243 is a valve provided in the first cooling water passage 231 and the fourth valve 244 is a valve provided in the second cooling water passage 232.

The control unit can control the valves as follows when it is required to heat the heating water of the district heating required for the district heating.

The control unit first opens the first and second valves 241 and 242, and closes the third and fourth valves 243 and 244. The control unit then performs control to cause the working fluid to circulate along the circulating flow path 220 between the heat exchanger 210 and the evaporator 110. For this purpose, the control unit can operate the pump in the circulating flow path 220. The control unit controls the heating water to be supplied to the condenser 140 via the absorber 120 to heat the heating water after the district heating. To this end, the control unit may open the valves 251, 252 of FIG. 3 and close the valves 253, 254 of FIG. The control unit can operate the pump in the flow path after such control.

Through the above-described control, the system according to the present embodiment can heat the heating water after the district heating and utilize it for district heating again.

By way of reference, the system of FIG. 3 may be implemented via a three-way valve. For example, the first valve 241 and the third valve 243 may be replaced by a single three-way valve installed at the connection point A.

Next, the control unit can control the valves as follows when it is required to cool the number of cooling of the district cooling due to the request of the district cooling.

The control unit first closes the first and second valves 241 and 242, and opens the third and fourth valves 244. [ The control unit controls the number of cooling water to flow sequentially through the first cooling water flow path 231, the first flow path 221, the second flow path 222 and the second cooling water flow path 232 in order to cool the cooling water after the district cooling. . For example, the control unit may operate the pump in the circulating flow passage 220 after controlling the valves 241 to 244 as described above. Through the above control, the system according to the present embodiment can cool the cooling water after the district cooling and utilize the cooling water for the district cooling again.

For reference, the control unit can perform control to switch from the district heating to the district cooling if the temperature of the heating water returned after the district heating is higher than the reference temperature. The high temperature of the returned heating water means that the outside temperature is high, so that the heating water does not consume much energy in heating. Therefore, when the temperature of the returned heating water is higher than a certain temperature, the control unit can determine that the heating is unnecessary and the cooling is necessary because the external temperature is high. The reference temperature may be 60 ° C.

Meanwhile, it is preferable that the fluid heated in the condenser 140 at the time of district cooling is heated in a lower temperature range than the fluid heated in the condenser 140 at the district heating. To this end, the system according to the present embodiment may be associated with a generating device (not shown) for generating waste solid fuel (SRF) in the waste.

The above apparatus needs to remove moisture from the waste to produce waste solid fuel from the waste. For this purpose, the above apparatus uses hot water. That is, the waste is heated through hot water to remove moisture from the waste. After such use, the hot water needs to be heated again, and the required temperature at this time is lower than the temperature required for the heating water of the district heating. The system according to the present embodiment can heat the hot water of the above apparatus through the condenser 140 or the absorber 120 and the condenser 140 of the heat pump 100 while cooling the cooling water for local cooling have.

In order to perform such heating, the control unit may perform control to supply the hot water to the condenser 140, or to the condenser 140 via the absorber 120. For example, the control unit may close the valves 251 and 252 of FIG. 3 and open the valves 253 and 254 of FIG. 3. The control unit can operate the pump in the flow path after such control.

The foregoing description of exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is to be noted that various changes and modifications may be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: Heat pump
110: Evaporator (Eva.)
120: absorber (Abs)
130: player (Gen.)
140: Condenser (Con.)
200: first heat source unit
210: heat exchanger
220: circulation channel
300: second heat source unit
400: steam turbine
410:
420: Storage tank

Claims (13)

A heat pump having an evaporator, an absorber, a regenerator and a condenser;
A first heat source unit for providing energy required for the refrigerant of the heat pump to evaporate in the evaporator; And
And a second heat source portion for providing energy required for the absorbent absorbing the refrigerant in the absorber to separate into the refrigerant and the absorbent in the regenerator,
The first heat source is supplied with energy from exhaust steam discharged after operation of the steam turbine,
Wherein the second heat source unit is supplied with energy from the process steam added during the operation of the steam turbine. The method according to claim 1,
Wherein the condenser heats the heating water of the district heating by condensing the refrigerant separated from the absorbent in the regenerator. The method of claim 2,
The process steam added during operation of the steam turbine is separated into a first stream and a second stream,
Wherein the first stream provides energy to the second heat source,
Wherein the second stream provides energy to a third heat source for reheating the hot water discharged from the condenser. The method according to claim 1,
Wherein the first heat source unit includes a heat exchanger for heat exchange between the exhaust steam and the working fluid and a circulation flow path for circulating the working fluid between the heat exchanger and the evaporator,
Wherein the refrigerant is evaporated in the evaporator by the working fluid in the circulation channel. The method of claim 4,
Wherein the exhaust vapors supplied to the heat exchanger bypass at least a portion of the exhaust vapors supplied to the condenser at the front end of the condenser for condensing the exhaust vapors. The method of claim 5,
Further comprising a storage tank for storing condensed water generated by condensing the exhaust steam supplied to the heat exchanger after heat exchange,
Wherein the condensed water stored in the storage tank is mixed with the condensed water generated in the condenser. The method of claim 6,
The process steam added during operation of the steam turbine is separated into a first stream and a second stream,
Wherein the first stream is supplied to the storage tank after being supplied with energy to the second heat source portion,
Wherein the second stream is supplied to the storage tank after energy is supplied to the third heat source for heating the heated water discharged from the district heating heated by the condenser again, . The method of claim 4,
A first cooling water channel for supplying cooling water for district cooling to the first channel of the circulation channel for supplying the working fluid from the heat exchanger to the condenser side; And
Further comprising a second cooling water flow passage for discharging the cooling water from the second flow path in the circulation flow path for supplying the working fluid from the condenser side to the heat exchanger. The method of claim 8,
A first valve provided in the first flow path between the heat exchanger and a connection point between the first flow path and the first cooling water flow path;
A second valve provided in the second flow path between the heat exchanger and a connection point between the second flow path and the second cooling water flow path;
A third valve provided in the first cooling water passage;
A fourth valve provided in the second cooling water passage; And
Further comprising a control unit for selecting one of the district heating and the district cooling and controlling the first to fourth valves. The method of claim 9,
Wherein the control unit performs control to switch from the district heating to the district cooling when the temperature of the heating water returning after the district heating is equal to or higher than the reference temperature. The method of claim 9,
The control unit, when a district heating is requested,
Opening the first and second valves,
Closing the third and fourth valves,
Circulating the working fluid between the heat exchanger and the evaporator through the circulation passage,
Wherein the heating water is supplied to the condenser so as to heat the heating water after the district heating. The method of claim 9,
The control unit, when a local cooling is requested,
Closing the first and second valves,
The third and fourth valves are opened,
An absorption type heat pump that performs control to cause the cooling water to flow sequentially to the first cooling water flow path, the first flow path, the second flow path, and the second cooling water flow path in order to cool the cooling water after the district cooling, Waste heat recovery system using. The method of claim 11,
The control unit, when a local cooling is requested,
An absorption type heat pump is provided for heating the waste to remove moisture in the waste in the generation apparatus for generating waste solid fuel in the waste and performing control to supply the high temperature water to the condenser to reheat the discharged hot water Waste heat recovery system.

Images