KR20180078039A - 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 working steam generated from a steam generator, which generates steam to be supplied to 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 energy required for the absorbent absorbing the refrigerant in the absorber to be separated into the refrigerant and the absorbent in the regenerator, wherein the first heat source comprises: an exhaust steam discharged after the operation of the steam turbine And the second heat source is supplied with energy from an operation steam generated from a steam generator that generates steam to be supplied to the steam turbine.

According to the present invention, the waste heat of the exhaust steam can be efficiently recovered through the absorption heat pump and the heat of the exhaust steam is indirectly transferred to the heat pump, so that the control of the system is easy.

1 is a conceptual diagram conceptually showing a waste heat recovery system according to an 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 shows a combined power generation system employing a steam turbine, a gas turbine, and an arrangement recovery boiler.

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.

FIG. 1 is a conceptual view conceptually showing a waste heat recovery system according to an embodiment 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 be roughened to 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. Since the heat source units 200 and 300 are all supplied with energy through the recovery of waste heat, the system according to the present embodiment has a very high efficiency of the entire system.

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. For reference, a heat pump can implement not only heating but also cooling.

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.

The exhaust steam of the steam turbine 400 is supplied to the condenser 410. The condenser 410 is a device for condensing exhaust steam. By such condensation, a second condensed water to be described later is generated. The condenser 410 may be air-cooled using a fan, or water-cooled using sea water or the like. Water-cooled condensers are generally applied to systems with large generating capacity. Since the power generation capacity is large in the water-cooled type, the guide pipe 420 for guiding the exhaust steam from the steam turbine 400 to the condenser 410 is also formed with a very large diameter.

Accordingly, the heat exchanger 210 of the first heat source unit 200 can be implemented inside the guide pipe 420. It can be assumed that the circulating flow path 220 simply passes through the inside of the guide pipe 420. In this case, the circulating flow path provided inside the guide pipe functions as a heat exchanger.

In this way, by providing the heat exchanger 210 inside the guide pipe 420, the waste heat recovery system according to the present embodiment can be applied to the conventional power generation system with only a slight operation, The required energy can be easily supplied to the evaporator 110 only by controlling the flow rate of the working fluid flowing along the evaporator 110.

The waste heat recovery system according to this embodiment also helps the heat exchanger 210 to condense the exhaust vapors. Therefore, the power consumed by the condenser 410 can be reduced. For example, when the condenser is air-cooled, the consumption power of the fan can be reduced, and when the condenser 410 is water-cooled, the consumption power of the pump can be reduced.

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 second heat source unit

The second heat source unit 300 is supplied with energy from the steam generated from the steam generator 510 that generates steam to be supplied to the steam turbine 400. Where the working steam can be generated in the first condensate discharged from the steam drum 520 of the steam generator 510.

A steam generator 510, such as an array recovery boiler (HRSG), typically includes a steam drum 520. The steam drum 520 separates the steam and the saturated liquid (first condensed water) from the supplied water-in-water mixture or from the water-based mixture in which the supplied steam is partially condensed. It is difficult for impurities to enter the steam. Therefore, the impurities in the mixture are mainly mixed with the saturated solution, and the saturated solution containing a large amount of impurities is generally discarded to the outside. This saturated liquid is also called continuous blowdown. However, the saturated liquid is in a state of high temperature and pressure. The waste heat recovery system according to the present embodiment is also characterized in that waste heat is recovered from the saturated liquid (first condensed water).

However, since the saturated liquid is in a high pressure state, the pressure can be lowered before it is discharged to the outside. Due to the pressure drop, some of the saturated liquid may be vaporized and converted to a vapor stream. That is, the saturated liquid (first condensed water) discharged from the steam drum 520 of the steam generator 510 can be changed into a radix mixture by a pressure change. The system according to the present embodiment may further include a water separator 530 to separate the gaseous stream and the liquid stream from the water mixture.

The gaseous stream separated from the radix mixture provides energy to the second heat source 300 as the working steam. In this way, the steam for supplying energy to the second heat source 300 can be generated from the steam generator 510.

On the other hand, when energy can not be sufficiently supplied to the second heat source unit 300 only by the vapor stream, a part of the steam generated in the steam generator 510 may be supplied to the water separation unit 530 (See "Additional Steam" in the previous section). That is, some of steam to be supplied to the steam turbine 400 from the steam generator 510 may be bypassed and supplied to the water separator 530. Since the steam generated in the steam generating apparatus 510 is very high in temperature, it is suitable for providing additional energy to the second heat source unit 300.

Alternatively, in the case of performing a daily start-up and stop (DSS) operation in which the steam turbine is operated only during the daytime in the combined-cycle power generation including the steam turbine, additional steam may be supplied to the radewaste- have.

If the supply of steam is suddenly stopped to stop the operation of the steam turbine, a thermal shock may be applied to the steam turbine. To prevent this, the supply of steam is gradually reduced. For this purpose, the steam generated by the steam generator 510 and supplied to the steam turbine 400 is bypassed to the condenser 410, and the amount of steam to be bypassed is gradually increased. However, in the system according to the present embodiment, steam can be bypassed to the water separator 530 instead of the condenser 410 in order to recover waste heat that has been discarded. Since the system according to the present embodiment supplies the additional steam to the water separator 530, the efficiency of the entire system can be improved as compared with the conventional system.

Even when starting the operation of the steam turbine, the supply of steam is gradually increased to prevent the occurrence of thermal shock and to preheat the steam turbine. To this end, steam, which is generated in the steam generator 510 and is to be supplied to the steam turbine 400, is bypassed to the condenser 410, and the amount of steam to be bypassed is gradually reduced. However, in the system according to the present embodiment, steam can be bypassed to the water separator 530 instead of the condenser 410 in order to recover waste heat that has been discarded.

The waste heat recovery system according to the present embodiment is excellent in the efficiency of the entire system because the waste heat is recovered from the exhaust steam and the saturated liquid (first condensed water), which are difficult to utilize waste heat.

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 the district heating can be heated through the condenser 140, or through the absorber 120 and the condenser 140.

Heating section

The waste heat recovery system according to the present embodiment may further include a heating unit 540 for heating the second condensed water discharged from the condenser 410. The heating unit 540 is provided in a supply line 430 for supplying the second condensed water to the steam generator 510. Since the second condensed water is vaporized again in the steam generator 510, it is preferable that the second condensed water is heated before being supplied to the steam generator 510. Such heating is performed in the heating unit 540, and the system according to the present embodiment can have a very high overall efficiency due to the heating unit 540.

The heating unit 540 can receive the energy required for heating the second condensed water from the liquid stream discharged from the water separator 530. That is, the liquid stream may be discharged from the water separation unit 530 and supplied to the heating unit 540. Further, the heating unit 540 may be supplied with energy from the operation steam. To this end, the working steam may provide energy to the second heat source unit 300 and may be supplied to the heating unit 540 after being condensed to supply energy to the heating unit 540. The system according to the present embodiment can recover the waste heat even in a liquid stream or the like that has been thrown away into the waste water, so that the overall efficiency can be very excellent.

The heating unit 540 may be supplied with at least a part of the heated water heated in the condenser 140. In particular, when the demand for heating water is low as in the summer, all of the heating water may be supplied to the heating unit 540. Accordingly, the system according to the present embodiment can appropriately utilize the heating water even in summer.

Steam turbines and steam generators

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.

And the steam generator may be an arrangement recovery boiler (HRSG). The combined power generation system may include a steam turbine, a gas turbine, and an arrangement recovery boiler as shown in FIG. The waste heat recovery system according to the present embodiment can be implemented between the condenser of the system of FIG. 3 and the arrangement recovery boiler.

The steam generator may also be a steam boiler. Flammable wastes are generally incinerated. The energy generated during the incineration can be used to generate steam in the steam boiler, and the generated steam can be used to operate the steam turbine. In such a system, a waste heat recovery system may be implemented between a steam turbine (or a condenser of a steam turbine) and a steam boiler.

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:
510: Steam generator
520: steam drum
530:

Claims (14)

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 is supplied with energy from an operation steam generated from a steam generator for generating steam to be supplied to 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 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 3,
Wherein the heat exchanger is provided inside a guide pipe for guiding the exhaust steam discharged from the steam turbine to a condenser for condensing the exhaust steam. The method according to claim 1,
Wherein the operating steam is generated in the first condensed water discharged from the steam drum of the steam generating apparatus. The method of claim 5,
Further comprising a water separator for separating the vapor stream and the liquid stream from the water vapor mixture produced in the pressure change from the first condensed water discharged from the steam drum of the steam generator,
Wherein the gaseous stream provides energy to the second heat source as the operating steam. The method of claim 6,
Wherein part of the steam generated by the steam generator is supplied to the water separator when it is required to further provide energy to the second heat generator. The method of claim 6,
Wherein at least a part of steam generated in the steam generator and supplied to the steam turbine is bypassed to the water separator and the amount of steam to be bypassed is gradually increased when the operation of the steam turbine is stopped, Waste heat recovery system using. The method of claim 6,
Wherein at least a part of steam generated in the steam generator and supplied to the steam turbine is bypassed to the water separator while the amount of steam to be bypassed is gradually reduced when the operation of the steam turbine is started, Waste heat recovery system using. The method of claim 6,
Further comprising a heating unit which is provided in a supply line for supplying the steam generated by the condensed water discharged from the condenser for condensing the discharged steam discharged after the operation of the steam turbine and for heating the second condensed water by heat exchange, Waste Heat Recovery System Using Absorption Heat Pump. The method of claim 10,
Wherein the heating unit is supplied with energy from the liquid stream discharged from the water separation unit. The method of claim 10,
Wherein the operating steam supplies energy to the second heat source unit and is supplied to the heating unit to supply energy to the heating unit after being condensed. The method of claim 10,
Wherein the condenser heats the heating water of the district heating by the condensation of the refrigerant separated from the absorbent in the regenerator,
Wherein at least a part of the heating water heated by the condenser is supplied to the heating unit to supply energy to the heating unit. The method according to claim 1,
Wherein the steam generating device is an arrangement recovery boiler (HRSG) or a steam boiler.

Images