JP2016148304A - Power generation system and power generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation system and power generation method capable of increasing a power generation amount and reducing the size of a condenser.SOLUTION: A power generation system includes: a first power generation system 3 containing a boiler 1, a first steam turbine 2 and a condenser 16; and a second power generation system 6 configured to drive a second steam turbine 5 with overheated steam obtained, by evaporating a low boiling point medium having a lower boiling point than a medium of the first generation system 3 with an evaporator 4. At least a part of exhaust steam of the first steam turbine 2 is subjected to heat exchange with at least one of boiler water and steam in a steam drum 10 of the boiler 1 for overheating thereby to obtain overheated steam, and the overheated steam is used as a high temperature side heat medium of the evaporator 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power generation system and a power generation method using waste heat from a waste incinerator.

  Conventionally, power generation facilities for waste incinerators that generate power using waste heat from waste incinerators are composed of the same equipment as general thermal power plants, and perform Rankine cycle using steam as the working fluid. As shown in FIG. 4, waste is incinerated in the combustion furnace 7, heat is absorbed from the combustion exhaust gas by the boiler 1 to generate superheated steam, and further heated by the superheater 11 to be generated by the condensate turbine 2. Incineration power generation is known (for example, Patent Documents 1 and 2). In the figure, reference numeral 24 denotes a deaerator for heating the feed water to the boiler 1 with steam extracted from the condensate turbine 2 to reduce dissolved oxygen in the feed water.

  The steam exhausted from the condensing turbine 2 is cooled by the condenser 16 and returned to water, and then returned to the boiler 1 via the deaerator 24 and the like. In the waste incineration power generation of this steam cycle, only about 20% of the energy held by the exhaust steam at the inlet of the condensing turbine 2 is used, and the remaining 80% is radiated from the condenser (condenser) to the atmosphere. It has become.

JP 2014-088812 A JP 2013-002393 A

  In the conventional waste incineration power generation, only about 20% of the superheated steam generated in the boiler can be used, and the rest is a heat dissipation loss.

  In addition, the condenser for heat dissipation becomes large, and the power of the air cooling fan of the condenser consumes 5 to 6% of the generated power, which is inefficient.

  Therefore, the main object of the present invention is to provide a power generation system and a power generation method capable of increasing the amount of power generation and downsizing the condenser.

  In order to achieve the above object, a first power generation system according to the present invention includes a first power generation system including a boiler, a first steam turbine, and a condenser, and a low boiling point lower than that of the medium of the first power generation system. A second power generation system that drives the second steam turbine using superheated steam obtained by evaporating the medium with an evaporator, and at least a part of the exhaust steam of the first steam turbine is in a can in the steam drum of the boiler Superheated steam obtained by superheating by heat exchange with water or steam is used as the high temperature side heat medium of the evaporator.

  The second power generation system according to the present invention includes a first power generation system including a boiler, a first steam turbine, and a condenser, and a low boiling point medium having a boiling point lower than that of the medium of the first power generation system. A second power generation system that drives the second steam turbine using the evaporated superheated steam, and at least a part of the exhaust steam of the first steam turbine exchanges heat with the steam discharged from the steam drum of the boiler The superheated steam obtained by overheating by heating is used as the high temperature side heat medium of the evaporator.

  In addition, the third power generation system according to the present invention includes a first power generation system including a boiler, a first steam turbine, a condenser, and a deaerator, and a low boiling point lower than that of the medium of the first power generation system. A second power generation system that drives the second steam turbine using superheated steam obtained by evaporating the medium with an evaporator, and at least a part of the exhaust steam of the first steam turbine with the medium in the deaerator. The superheated steam obtained by overheating by heat exchange is used as the high temperature side heat medium of the evaporator.

  The first power generation method according to the present invention includes a first step of generating superheated steam with a boiler, a second step of driving the first steam turbine using superheated steam, and the exhaust steam of the first steam turbine. A third step of obtaining superheated steam by heat-exchanging at least a part thereof with can water or steam in the steam drum of the boiler, and the superheated steam obtained in the third step and the first steam turbine Heat exchange with a low boiling point medium having a boiling point lower than that of the medium for driving the low boiling point medium to obtain superheated steam of the low boiling point medium, and using the steam of the low boiling point medium obtained in the fourth step, the second step And a fifth step of driving the steam turbine.

  The second power generation method according to the present invention includes a first step of generating superheated steam with a boiler, a second step of driving the first steam turbine using the superheated steam, and the exhaust steam of the first steam turbine. A third step of superheating at least a part of the steam by exchanging heat with steam discharged from the steam drum of the boiler to obtain superheated steam, and driving the superheated steam obtained in the third step and the first steam turbine Heat exchange with a low boiling point medium having a lower boiling point than the medium to be heated to obtain superheated steam of the low boiling point medium, and a second steam turbine using the steam of the low boiling point medium obtained in the fourth step And a fifth step of driving.

  The third power generation method according to the present invention includes a first step of generating superheated steam with a boiler, a second step of driving the first steam turbine using the superheated steam, and the exhaust steam of the first steam turbine. A third step of obtaining superheated steam by superheating at least a part of the heat exchange with a heat medium in a deaerator for degassing the heat medium of the first steam turbine, and the superheat obtained in the third step A fourth step of obtaining a superheated steam of the low boiling point medium by exchanging heat between the steam and a low boiling point medium having a lower boiling point than the medium driving the first steam turbine; and the low boiling point medium obtained in the fourth step And a fifth step of driving the second steam turbine using the steam.

  According to the present invention, the power generation amount can be increased by so-called binary power generation using the exhaust steam of the steam turbine that has been discarded.

  In addition, since the amount of exhaust steam from the steam turbine sent to the condenser can be reduced, the air-cooled condenser that requires a large installation space can be reduced in size.

  Furthermore, since the electric power consumed by the fan of the air-cooled condenser can be reduced, the total electric power can be increased.

1 is a system diagram showing a first embodiment of a power generation system according to the present invention. It is a systematic diagram which shows 2nd Embodiment of the electric power generation system which concerns on this invention. It is a systematic diagram which shows 3rd Embodiment of the electric power generation system which concerns on this invention. It is a systematic diagram which shows the conventional electric power generation system.

  Embodiments of a power generation system according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar component through all the Examples.

  As shown in FIG. 1, the first embodiment of the power generation system according to the present invention includes a first power generation system 3 that drives a first steam turbine 2 using superheated steam heated by a boiler 1, and the first power generation system. And a second power generation system 6 that drives the second steam turbine 5 using superheated steam obtained by evaporating a low boiling point medium having a boiling point lower than that of the medium 3 by the evaporator 4.

  The steam cycle of the first power generation system 3 uses water as a medium. The steam cycle of the second power generation system 6 is a so-called binary power generation steam cycle. As a working medium, an organic medium having a standard boiling point lower than 100 ° C., for example, a low boiling point medium such as HFC245fa, HFC134a, isopentane, normal pentane, or aqueous ammonia. Can be used.

  The boiler 1 may be an exhaust heat boiler that uses exhaust heat of combustion exhaust gas from the incinerator 7. An incinerator 7 in the illustrated example is a stoker-type incinerator, in which a water tube group 1a of a boiler 1 is disposed in a flue 8 of the incinerator 7, and a steam drum 10 is disposed above the water tube group 1a. .

  The steam generated in the boiler 1 is superheated by the superheater 11 to drive the first steam turbine 2 and generate electric power by the first generator 12. The first steam turbine 2 is preferably a condensate steam turbine that can obtain a larger amount of power generation than the back pressure type.

  The exhaust steam that has worked in the first steam turbine 2 is separated from the moisture in the drain tank 13, and then a part thereof is sent to the steam drum 10 through the pipe 14, and the rest is sent to the condenser 16 through the pipe 15. Sent. The pipe line 14 communicates with a first heat exchanger 17 constituted by a heat transfer pipe provided in the steam drum 10, and the exhaust steam sent from the pipe line 14 to the first heat exchanger 17 is in the steam drum 10. It becomes superheated steam by exchanging heat with canned water at about 250 ° C. and / or steam. The superheated steam generated in the first heat exchanger 17 is sent to the evaporator 4 through the pipe 118 and acts as a high temperature side heat medium for the evaporator 4 to evaporate the low boiling point medium circulating in the second power generation system 6. Overheated.

  The medium drained in the drain tank 13 is sent to the condensate tank 20 through the pipe 19. The medium condensed by the heat exchange with the low boiling point medium in the evaporator 4 is sent to the condensate tank 20 through the pipe line 21. The water condensed by the condenser 16 is sent to the condensate tank 20 through the pipe line 22. The water in the condensate tank 20 is sent to the deaerator 24 by the pump 23, deaerated by the deaerator 24, and then supplied to the steam drum 10 from the deaerator 24 by the pump 25.

  Although not shown, a flow rate adjusting means such as a valve for adjusting the flow rate of the turbine exhaust steam from the first turbine 2 can be interposed at appropriate portions of the pipe lines 14 and 15 through which the exhaust steam passes.

  The low boiling point medium that has become superheated steam in the evaporator 4 drives the second steam turbine 5 and generates power by the second generator 30. The exhaust steam discharged from the second steam turbine 5 is condensed by the condenser 31 and returned to the liquid, and the condensed low boiling point medium is pumped to the evaporator 4 by the pump 32. The refrigerant having exchanged heat with the low boiling point medium in the condenser 31 is cooled in the cooling tower (cooling tower) 33 and sent to the condenser 31 again by the pump 34, thereby circulating as a working medium of the second power generation system 6.

  The power generation efficiency of the present invention having the above configuration is estimated by comparison with the conventional example shown in FIG.

  In the conventional example shown in FIG. 4, the temperature (° C.), pressure (atm or atg), enthalpy h (kcal / kg), flow rate (kg / hour), and generator output (kW) in each part a1 to d1 are as follows. It was.

a1: Steam drum atmosphere; 250 ° C, 45atg
b1: Steam at the inlet of the steam turbine; 400 ° C, 40 atg, 2470 kg / hour, h = 768 kcal / kg
c1: Generator output; 472kW
d1: Outlet wet steam of steam turbine; 60 ° C, 0.2atm, h = 600kcal / kg
e1: Condenser fan power consumption: 30kW
Next, in the embodiment of the present invention shown in FIG. 1, each part a <b> 2 to j <b> 2 is calculated as follows. A trial calculation (approximate) was made on the case where about 50% of the turbine exhaust steam from the first steam turbine 2 was drawn to the first heat exchanger 17 through the pipe 14. Note that heat dissipation and pressure loss were ignored for the sake of estimation. The boiler, the first steam turbine, and the first generator of FIG. 1 are the same as the boiler, the steam turbine, and the generator of the conventional example of FIG. In the following, detailed calculations are omitted.

a2: Atmosphere in steam drum; 250 ° C, 45atg
b2: First steam turbine inlet steam; 400 ° C., 40 atg, 2418 kg / hour c2: Output of the first generator; 462 kW
d2: Turbine exhaust steam drawn from the drain tank; 60 ° C, 0.2atm, 1200kg / hr, h = 623kcal / kg
e2: Condenser fan power consumption: approx. 15kW
f2: Evaporator inlet side steam; 120 ° C, h = 651kcal / kg
g2: Vapor outlet side steam; 60 ° C, 0.2 atm
h2: Output of the second generator; 80kW
i2: Cooling tower power consumption: 2kW
j2: Refrigerant circulation pump power consumption: approx. 5kW
As shown by the above calculation results, the state of the turbine exhaust steam drained by the drain tank 13 is 0.2 atm, 60 ° C., and enthalpy 623 kcal / kg. This steam is heated to 120 ° C. by the first heat exchanger 17 in the steam drum 10. The temperature of the can water in the steam drum 10 is about 250 ° C. (pressure 45 atg). The amount of generated steam in the boiler 1 decreases according to the amount of superheat. However, since the turbine exhaust steam is superheated in a gas phase without phase change and the amount of heat (sensible heat) necessary for the superheat is not large, the reduction in the amount of generated steam in the boiler 1 is about 2%. Therefore, the power generation amount in the first steam turbine 2 is reduced by 2% (10 kW). Further, since the amount of exhaust steam sent to the air-cooled condenser 16 is about half, the power consumption of the air-cooling fan of the condenser 16 is reduced by about half (about 15 kW).

  Changes in power generation and power consumption are generally as follows.

-10 kW (reduction in power generation amount of the first steam turbine 2) +15 kW (reduction in power consumption of the air cooling fan of the condenser 16) +82 kW (power generation amount of the second generator 30) -5 kW (refrigerant circulation for cooling tower) Power consumption of pump 32) -2 kW (cooling tower power consumption of cooling tower 33) = 80 kW
Therefore, according to the above calculation, the power generation amount of the embodiment of the present invention of FIG. 1 is increased by about 17% as compared with the conventional example of FIG.

  It is impossible to directly use the turbine exhaust steam of the first steam turbine 2 as a heat source of the second power generation system 6 because the exhaust steam temperature is about 60 ° C. according to the catalog value of the binary generator. Moreover, if it says from the power generation efficiency of the 2nd power generation system 6, if it is not a heat source of 100 degreeC or more, efficiency will decline on the contrary.

  FIG. 2 is a system diagram showing a second embodiment of the power generation system according to the present invention. The power generation system according to the second embodiment includes the steam discharged from the steam drum 10 and the exhaust steam of the first steam turbine 2 in the second heat exchanger 40 disposed outside the steam drum 10 instead of in the steam drum 10. It differs from the electric power generation system of the said 1st Embodiment in the point which is overheating by carrying out heat exchange of at least one part. The superheated steam superheated by the second heat exchanger 40 is used as the high temperature side heat medium of the evaporator 4, and the low boiling point medium circulating in the second power generation system 6 is evaporated and superheated. Other configurations are the same as those in the first embodiment. In the illustrated example, the superheated steam superheated by the boiler 1 and the superheater 11 is sent to the first steam turbine through the pipe 41, but the pipe 42 branched from the pipe 41 is the second heat exchanger 40. Connected to the high temperature side. The exhaust steam of the second steam turbine 2 is superheated from 60 ° C. to 130 ° C., for example, by the second heat exchanger 40 and sent to the high temperature side of the evaporator 4. Although not shown, a valve or the like for adjusting the flow rate can be appropriately interposed in the pipelines 42 and 41.

  FIG. 3 is a system diagram showing a third embodiment of the power generation system according to the present invention. The power generation system of the third embodiment superheats a part or all of the exhaust steam of the first steam turbine 2 by exchanging heat with the medium in the deaerator 24, and converts the obtained superheated steam into the evaporator 4. Different from the first embodiment in that the low boiling point medium of the second power generation system 6 is evaporated and superheated as the high temperature side heat medium, the other configurations are the same as those in the first embodiment.

  That is, in the third embodiment, the pipe line 51 connected to the drain tank 13 is connected to the third heat exchanger 52 in the deaerator 24, and the third heat exchanger 52 is further connected to the evaporator by the pipe line 53. 4 is connected to the high temperature side. The heat medium in the deaerator 24 is, for example, about 158 ° C. due to heating by the extracted steam from the first steam turbine 2. Accordingly, the turbine exhaust steam discharged from the first steam turbine 2 is drained by the drain tank 13, passes through the pipe 51 and is superheated from about 60 ° C. to about 130 ° C. by the third heat exchange unit 52, and then the evaporator 4. Sent to the high temperature side.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Boiler 2 1st steam turbine 3 1st power generation system 4 Evaporator 5 2nd steam turbine 6 2nd power generation system 7 Incinerator 10 Steam drum 11 Superheater 24 Deaerator

To achieve the above object, engagement Ru power generation system in the present invention, a boiler, a first steam turbine, a condenser, and a first power generation system including a deaerator, boiling point than the medium of the first generator line A second power generation system that drives a second steam turbine using superheated steam obtained by evaporating a low-boiling-point medium with a low boiling point using an evaporator, and at least part of the exhaust steam of the first steam turbine includes the deaerator The superheated steam obtained by overheating by exchanging heat with the medium inside is used as the high temperature side heat medium of the evaporator.

Further, engagement Ru power generation method according to the present invention comprises a first step of generating superheated steam in a boiler, and a second step of driving the first steam turbine with superheated steam, the exhaust steam of the first steam turbine A third step of obtaining superheated steam by heat-exchanging at least partly by heat exchange with a heat medium in a deaerator for degassing the heat medium of the first steam turbine; and the superheated steam obtained in the third step And a low boiling point medium having a boiling point lower than that of the medium driving the first steam turbine, to obtain a superheated steam of the low boiling point medium, and a low boiling point medium obtained in the fourth step. And a fifth step of driving the second steam turbine using steam.

It is a systematic diagram showing the first reference form of the power generation system according to the present invention. It is a systematic diagram which shows the 2nd reference form of the electric power generation system which concerns on this invention. 1 is a system diagram showing an embodiment of a power generation system according to the present invention. It is a systematic diagram which shows the conventional electric power generation system.

As shown in FIG. 1, a first reference form of a power generation system according to the present invention is a first power generation system 3 that drives a first steam turbine 2 using superheated steam heated by a boiler 1, and the first power generation system. And a second power generation system 6 that drives the second steam turbine 5 using superheated steam obtained by evaporating a low boiling point medium having a boiling point lower than that of the medium 3 by the evaporator 4.

The exhaust steam that has worked in the first steam turbine 2 is separated from the moisture in the drain tank 13, and then a part thereof is sent to the steam drum 10 through the pipe 14, and the rest is sent to the condenser 16 through the pipe 15. Sent. The pipe line 14 communicates with a first heat exchanger 17 constituted by a heat transfer pipe provided in the steam drum 10, and the exhaust steam sent from the pipe line 14 to the first heat exchanger 17 is in the steam drum 10. It becomes superheated steam by exchanging heat with canned water at about 250 ° C. and / or steam. Superheated steam generated by the first heat exchanger 17, evaporated low-boiling medium is sent to the evaporator 4 through the pipe line 1 8 acts as a high-temperature-side heat medium of the evaporator 4, circulates the second generation system 6 Let it overheat.

a1: Steam drum atmosphere; 250 ° C, 45atg
b1: Steam at the inlet of the steam turbine; 400 ° C, 40 atg, 2470 kg / hour, h = 768 kcal / kg
c1: Generator output; 472kW
d1: Outlet wet steam of steam turbine; 60 ° C, 0.2atm, h = 600kcal / kg
e1: Condenser fan power consumption: 30kW
Next, in the reference form of the present invention shown in FIG. 1, each part a <b> 2 to j <b> 2 is calculated as follows. A trial calculation (approximate) was made on the case where about 50% of the turbine exhaust steam from the first steam turbine 2 was drawn to the first heat exchanger 17 through the pipe 14. Note that heat dissipation and pressure loss were ignored for the sake of estimation. The boiler, the first steam turbine, and the first generator of FIG. 1 are the same as the boiler, the steam turbine, and the generator of the conventional example of FIG. In the following, detailed calculations are omitted.

FIG. 2 is a system diagram showing a second reference form of the power generation system according to the present invention. The power generation system of the second reference embodiment is configured such that the steam discharged from the steam drum 10 and the exhaust steam of the first steam turbine 2 are not in the steam drum 10 but in the second heat exchanger 40 arranged outside the steam drum 10. It differs from the electric power generation system of the said 1st reference form in the point which is overheating by carrying out heat exchange of at least one part. The superheated steam superheated by the second heat exchanger 40 is used as the high temperature side heat medium of the evaporator 4, and the low boiling point medium circulating in the second power generation system 6 is evaporated and superheated. Other configurations are the same as those of the first reference embodiment. In the illustrated example, the superheated steam superheated by the boiler 1 and the superheater 11 is sent to the first steam turbine through the pipe 41, but the pipe 42 branched from the pipe 41 is the second heat exchanger 40. Connected to the high temperature side. The exhaust steam of the second steam turbine 2 is superheated from 60 ° C. to 130 ° C., for example, by the second heat exchanger 40 and sent to the high temperature side of the evaporator 4. Although not shown, a valve or the like for adjusting the flow rate can be appropriately interposed in the pipelines 42 and 41.

FIG. 3 is a system diagram showing an embodiment of the power generation system according to the present invention. The power generation system of one embodiment superheats a part or all of the exhaust steam of the first steam turbine 2 by exchanging heat with the medium in the deaerator 24, and converts the obtained superheated steam to the high temperature of the evaporator 4. It differs from the first reference embodiment in that the low boiling point medium of the second power generation system 6 is evaporated and superheated as a side heat medium, and the other configuration is the same as the first reference embodiment.

That is, in the embodiment of the present invention, the pipe line 51 connected to the drain tank 13 is connected to the third heat exchanger 52 in the deaerator 24, and the third heat exchanger 52 is further evaporated by the pipe line 53. It is connected to the high temperature side of the vessel 4. The heat medium in the deaerator 24 is, for example, about 158 ° C. due to heating by the extracted steam from the first steam turbine 2. Accordingly, the turbine exhaust steam discharged from the first steam turbine 2 is drained by the drain tank 13, passes through the pipe 51 and is superheated from about 60 ° C. to about 130 ° C. by the third heat exchange unit 52, and then the evaporator 4. Sent to the high temperature side.

Claims (6)

A first power generation system including a boiler, a first steam turbine, and a condenser;
A second power generation system that drives a second steam turbine using superheated steam obtained by evaporating a low boiling point medium having a boiling point lower than that of the medium of the first power generation system with an evaporator;
The superheated steam obtained by superheating at least a part of the exhaust steam of the first steam turbine with at least one of the can water and steam in the steam drum of the boiler is heated on the high temperature side of the evaporator. A power generation system characterized by that. A first power generation system including a boiler, a first steam turbine, and a condenser;
A second power generation system that drives a second steam turbine using superheated steam obtained by evaporating a low boiling point medium having a boiling point lower than that of the medium of the first power generation system with an evaporator;
Superheated steam obtained by overheating at least part of the exhaust steam of the first steam turbine by heat exchange with steam discharged from the steam drum of the boiler is used as a high-temperature side heat medium for the evaporator. Characteristic power generation system. A first power generation system including a boiler, a first steam turbine, a condenser, and a deaerator;
A second power generation system that drives a second steam turbine using superheated steam obtained by evaporating a low boiling point medium having a boiling point lower than that of the medium of the first power generation system with an evaporator;
The superheated steam obtained by superheating at least a part of the exhaust steam of the first steam turbine by exchanging heat with the medium in the deaerator is used as a high temperature side heat medium of the evaporator. Power generation system. A first step of generating superheated steam in a boiler;
A second step of driving the first steam turbine using superheated steam;
A third step in which at least a part of the exhaust steam of the first steam turbine is heated by exchanging heat with at least one of can water and steam in the steam drum of the boiler to obtain superheated steam;
A fourth step of obtaining a superheated steam of the low boiling point medium by exchanging heat between the superheated steam obtained in the third step and a low boiling point medium having a lower boiling point than the medium driving the first steam turbine;
A fifth step of driving the second steam turbine using the steam of the low boiling point medium obtained in the fourth step;
A power generation method comprising: A first step of generating superheated steam in a boiler;
A second step of driving the first steam turbine using superheated steam;
A third step in which at least a part of the exhaust steam of the first steam turbine is superheated by heat exchange with steam discharged from the steam drum of the boiler to obtain superheated steam;
A fourth step of obtaining a superheated steam of the low boiling point medium by exchanging heat between the superheated steam obtained in the third step and a low boiling point medium having a lower boiling point than the medium driving the first steam turbine;
A fifth step of driving the second steam turbine using the steam of the low boiling point medium obtained in the fourth step;
A power generation method comprising: A first step of generating superheated steam in a boiler;
A second step of driving the first steam turbine using superheated steam;
A third step of obtaining superheated steam by overheating at least a part of the exhaust steam of the first steam turbine by heat exchange with a heat medium in a deaerator for degassing the heat medium of the first steam turbine;
A fourth step of obtaining a superheated steam of the low boiling point medium by exchanging heat between the superheated steam obtained in the third step and a low boiling point medium having a lower boiling point than the medium driving the first steam turbine;
A fifth step of driving the second steam turbine using the steam of the low boiling point medium obtained in the fourth step;
A power generation method comprising:

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