Power plant steam exhaust waste heat pump recovery system and recovery method

Abstract

The application discloses a thermal power plant exhausted steam waste heat heat pump recovery system and recovery method, the recovery system includes absorber, regenerator and condenser; the coolant steam input end of the absorber is directly connected with the exhausted steam output end of the steam turbine through a pipeline, the exhausted steam discharged from the steam turbine is directly introduced into the absorber as the coolant steam; in the absorber, the exhausted steam and the lithium bromide concentrated solution occur absorption reaction, generate lithium bromide dilute solution and release heat, the heat is used for heating the secondary network backwater; the lithium bromide dilute solution is transported to the regenerator, the lithium bromide dilute solution is heated by using a driving heat source, so that the lithium bromide dilute solution releases the coolant steam and is concentrated into lithium bromide concentrated solution, and the lithium bromide concentrated solution is transported back to the absorber for recycling; the coolant steam generated by the regenerator is introduced into the condenser, the condensation heat of the coolant steam is released to the secondary network backwater, and the coolant steam is condensed into water and discharged. The application simplifies the exhausted steam waste heat heating system, reduces heat transfer loss, and improves the exhausted steam waste heat utilization efficiency of the steam turbine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power technology and waste heat recovery, and particularly relates to a waste heat recovery system based on a lithium bromide absorption heat pump for directly utilizing the waste heat of turbine exhaust steam. BACKGROUND

[0002] A heat pump is an energy-saving device capable of transferring low-temperature heat to high-temperature heat, and mainly includes two types: a compression heat pump and an absorption heat pump. The compression heat pump is driven by a compressor, and the absorption heat pump is driven by a medium-high temperature heat source. The absorption heat pump is composed of an evaporator, an absorber, a regenerator and a condenser. The lithium bromide absorption heat pump uses water as a refrigerant and lithium bromide solution as an absorbent. Water absorbs heat from a low-temperature heat source in the evaporator to evaporate into steam, which is absorbed by a concentrated lithium bromide solution in the absorber to become a dilute solution while releasing absorption heat. The dilute solution is sent to the regenerator to be heated by a driving heat source to release water vapor, and the dilute solution is concentrated into a concentrated solution again to return to the absorber, completing the solution circulation. The water vapor generated in the regenerator is transferred to a medium-high temperature heat source in the condenser to condense into water and return to the evaporator, completing the refrigerant circulation.

[0003] The lithium bromide heat pump is widely used in waste heat recovery. At present, some power plants use lithium bromide heat pumps to recover waste heat from exhaust steam, and the process is as shown in Figure 1 The waste heat of turbine exhaust steam is first transferred to circulating water in the condenser, and then the circulating water enters the evaporator of the lithium bromide heat pump to evaporate into refrigerant steam, which then enters the absorber and carries heat to the condenser of the heat pump. The heat transfer process from the condenser to the evaporator involves the transfer of heat from exhaust steam to circulating water to refrigerant water to refrigerant steam.

[0004] This process has the problems of multiple heat transfer links, complex system, large heat loss and low efficiency. Therefore, there is an urgent need for a more efficient and simplified waste heat recovery system for exhaust steam. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a waste heat recovery system and method for recovering waste heat from exhaust steam in a power plant, so as to simplify the system structure, reduce heat transfer loss and improve the efficiency of waste heat utilization.

[0006] To achieve the above purpose, according to one aspect of the present application, a waste heat recovery system for recovering waste heat from exhaust steam in a power plant is provided, which comprises an absorber, a regenerator and a condenser. The absorber shell is provided with a refrigerant steam input end, a concentrated solution input end and a dilute solution output end. The refrigerant steam input end is directly connected to the exhaust steam output end of the turbine through a pipeline. The regenerator shell is provided with a refrigerant vapor output end, a concentrated solution output end and a dilute solution input end; the concentrated solution output end is connected with the concentrated solution input end of the absorber through a concentrated solution conveying pipeline, and the dilute solution input end is connected with the dilute solution output end of the absorber through a dilute solution conveying pipeline; The regenerator is internally provided with a regenerator heat exchanger, and an input end of the regenerator heat exchanger is connected with the driving steam output end of the steam turbine through a pipeline; The shell of the condenser is provided with a refrigerant vapor input end and a condensed water output end; the refrigerant vapor input end is connected with the refrigerant vapor output end of the regenerator through a pipeline; The absorber is internally provided with an absorber heat exchanger, and the condenser is internally provided with a condenser heat exchanger; the secondary network return water pipeline is connected with the absorber heat exchanger and the condenser heat exchanger in sequence.

[0007] As a preferred embodiment, the dilute solution conveying pipeline is provided with a solution pump.

[0008] As a preferred embodiment, an output end of the regenerator heat exchanger is connected with the low-pressure heater through a low-pressure heater return pipeline.

[0009] As a preferred embodiment, the dilute solution conveying pipeline and the low-pressure heater return pipeline are heat-exchanged through a heat source water heat exchanger.

[0010] As a preferred embodiment, the concentrated solution conveying pipeline and the dilute solution conveying pipeline are heat-exchanged through a solution heat exchanger.

[0011] According to another aspect of the present application, a waste heat heat pump recovery method for a power plant is provided, which uses the waste heat heat pump recovery system for a power plant as described above, and comprises the following steps: The exhaust steam discharged from the steam turbine is directly introduced into the absorber as refrigerant vapor; In the absorber, the exhaust steam is subjected to an absorption reaction with the lithium bromide concentrated solution to generate lithium bromide dilute solution and release heat, and the heat is used to heat the secondary network return water flowing therethrough; The lithium bromide dilute solution is conveyed to the regenerator; in the regenerator, the lithium bromide dilute solution is heated by a driving heat source to release refrigerant vapor and be concentrated into lithium bromide concentrated solution; the lithium bromide concentrated solution is conveyed back to the absorber for recycling; The refrigerant vapor generated by the regenerator is introduced into the condenser to release the condensation heat to the secondary network return water, and is condensed into water and then discharged.

[0012] As a preferred embodiment, the driving heat source is steam extracted from the steam turbine.

[0013] As a preferred embodiment, before the lithium bromide dilute solution enters the regenerator, the lithium bromide dilute solution is heat-exchanged with the lithium bromide concentrated solution returned from the regenerator in a solution heat exchanger.

[0014] This invention eliminates the need for a condenser and an evaporator, directly introducing turbine exhaust steam into the absorber of a lithium bromide heat pump. This simplifies the exhaust steam waste heat supply system, reduces heat transfer losses, and improves the utilization efficiency of turbine exhaust steam waste heat. Attached Figure Description

[0015] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0016] Figure 1 A schematic diagram of the lithium bromide heat pump heating process in thermal power plants in the existing technology; Figure 2 This is a schematic diagram of the process of the waste heat recovery system for thermal power plant exhaust steam described in this invention.

[0017] In the diagram, 1-steam turbine, 2-absorber, 3-regenerator, 4-condenser, 5-condenser, 6-evaporator, 7-exhaust steam delivery pipeline, 8-concentrated solution delivery pipeline, 9-dilute solution delivery pipeline, 10-regenerator heat exchanger, 11-drive steam delivery pipeline, 12-refrigerant steam delivery pipeline, 13-absorber heat exchanger, 14-condenser heat exchanger, 15-secondary network return water pipeline, 16-solution pump, 17-return low-pressure heater pipeline, 18-heat source water heat exchanger, 19-solution heat exchanger. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the present invention will be further described clearly and completely below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0019] In traditional processes, the heat from exhaust steam undergoes multiple indirect heat exchanges: exhaust steam → circulating water → refrigerant water → refrigerant steam. Each heat exchange results in irreversible temperature losses, leading to low thermal efficiency. The basic concept of this invention is to eliminate the need for condensers and evaporators, allowing the low-pressure, low-temperature exhaust steam from the turbine to directly enter the absorber as refrigerant steam and be absorbed by the solution. This eliminates two major intermediate heat exchange stages, significantly reducing heat transfer losses and improving the overall system thermal efficiency.

[0020] Based on the above ideas, such as Figure 2 As shown, a typical embodiment of the present invention provides a waste heat recovery system for thermal power plant exhaust steam, including an absorber 2, a regenerator 3, and a condenser 4.

[0021] The shell of the absorber 2 is provided with a refrigerant vapor input end, a concentrated solution input end and a dilute solution output end. The refrigerant vapor input end is directly connected with the exhaust steam output end of the steam turbine 1 through the exhaust steam delivery pipeline 7, so that the exhaust steam of the steam turbine directly enters the absorber 2 of the lithium bromide heat pump as the refrigerant vapor.

[0022] The shell of the regenerator 3 is provided with a refrigerant vapor output end, a concentrated solution output end and a dilute solution input end. The concentrated solution output end is connected with the concentrated solution input end of the absorber through the concentrated solution delivery pipeline 8, and the dilute solution input end is connected with the dilute solution output end of the absorber through the dilute solution delivery pipeline 9.

[0023] The regenerator 3 is internally provided with a regenerator heat exchanger 10, and the input end of the regenerator heat exchanger 10 is connected with the driving steam output end of the steam turbine 1 through the driving steam delivery pipeline 11. The output end of the regenerator heat exchanger 10 is connected to the low-pressure heater through the low-pressure heater return pipeline 17. The driving heat source from the steam turbine 1 enters the regenerator heat exchanger 10 to exchange heat with the lithium bromide dilute solution, and the driving heat source returns to the low-pressure heater after heat exchange.

[0024] The exhaust steam entering the absorber 2 and the lithium bromide concentrated solution from the regenerator 3 occur absorption reaction to generate lithium bromide dilute solution and release heat, and the lithium bromide dilute solution is delivered to the regenerator 3 by the solution pump 16, heated by the driving heat source to form refrigerant vapor and concentrated solution, and the concentrated solution returns to the absorber 2 through the throttle valve to complete the solution circulation.

[0025] The shell of the condenser 4 is provided with a refrigerant vapor input end and a condensed water output end; the refrigerant vapor input end is connected with the refrigerant vapor output end of the regenerator 3 through the refrigerant vapor delivery pipeline 12. The refrigerant vapor enters the condenser 4 to transfer heat to the heat network return water, and the condensed water goes to the water supply system and returns to the power plant steam-water system after chemical treatment.

[0026] The absorber 2 is internally provided with an absorber heat exchanger 13, and the condenser 4 is internally provided with a condenser heat exchanger 14, and the secondary network return water pipeline 15 is connected with the absorber heat exchanger 13 and the condenser heat exchanger 14 in sequence.

[0027] The secondary network return water flows through the absorber heat exchanger 13 and the condenser heat exchanger 14 in sequence, and the temperature of the secondary network return water is increased after absorbing heat, and the secondary network return water is used for heating water.

[0028] The dilute solution delivery pipeline 9 and the low-pressure heater return pipeline 17 exchange heat through the heat source water heat exchanger 18. Before the lithium bromide dilute solution enters the regenerator 3, the lithium bromide dilute solution exchanges heat with the water in the low-pressure heater return pipeline 17.

[0029] The concentrated solution delivery pipeline 8 and the dilute solution delivery pipeline 9 exchange heat through the solution heat exchanger 19. Before the lithium bromide dilute solution enters the regenerator 3, the lithium bromide dilute solution exchanges heat with the lithium bromide concentrated solution returned from the regenerator 3 in the solution heat exchanger 19.

[0030] Another typical embodiment of the present application provides a method for recovering waste heat of exhausted steam in a thermal power plant.

[0031] The exhausted steam discharged from the steam turbine 1 is directly introduced into the absorber 2 as refrigerant steam; In the absorber 2, the exhausted steam is absorbed by the concentrated lithium bromide solution to generate dilute lithium bromide solution and release heat, which is used to heat the secondary network return water; The dilute lithium bromide solution is delivered to the regenerator 3, in which the dilute lithium bromide solution is heated by the driving heat source from the steam turbine 1 to release refrigerant steam and be concentrated into concentrated lithium bromide solution; the concentrated lithium bromide solution is delivered back to the absorber 2 for recycling.

[0032] The refrigerant steam generated in the regenerator 3 is introduced into the condenser 4, and its condensation heat is released to the secondary network return water, and the condensed water is discharged.

[0033] From the perspective of heat transfer, the waste heat of the exhausted steam directly enters the absorber without passing through the condenser and the evaporator, reducing the heat transfer loss and improving the utilization efficiency of the waste heat of the exhausted steam. For the low-pressure and low-temperature water vapor of the exhausted steam in the thermal power plant, the waste heat recovery process provided by the present application has distinct features and technical advantages, which effectively improves the comprehensive energy utilization efficiency of the power plant.

[0034] The scope of protection of the present application is not limited to the above specific embodiments, and the present application can have various modifications and alterations for those skilled in the art, and any modification, improvement and equivalent replacement within the concept and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A waste heat recovery system for thermal power plant exhaust steam, comprising an absorber, a regenerator, and a condenser; characterized in that: The absorber shell is provided with a refrigerant vapor inlet, a concentrated solution inlet, and a dilute solution outlet; the refrigerant vapor inlet is directly connected to the exhaust steam outlet of the steam turbine via a pipeline; The regenerator housing is provided with a refrigerant vapor output end, a concentrated solution output end, and a dilute solution input end; the concentrated solution output end is connected to the concentrated solution input end of the absorber through a concentrated solution delivery pipeline, and the dilute solution input end is connected to the dilute solution output end of the absorber through a dilute solution delivery pipeline; The regenerator is equipped with a regenerator heat exchanger, and the input end of the regenerator heat exchanger is connected to the drive steam output end of the steam turbine through a pipeline. The condenser shell is provided with a refrigerant vapor inlet and a condensate outlet; the refrigerant vapor inlet is connected to the refrigerant vapor outlet of the regenerator via a pipeline. The absorber is equipped with an absorber heat exchanger, and the condenser is equipped with a condenser heat exchanger. The secondary network return water pipeline is connected to the absorber heat exchanger and the condenser heat exchanger in sequence.

2. The waste heat recovery system for thermal power plant exhaust steam according to claim 1, characterized in that: A solution pump is installed on the dilute solution delivery pipeline.

3. The waste heat recovery system for thermal power plant exhaust steam according to claim 1 or 2, characterized in that: The output of the regenerator heat exchanger is connected to the low-pressure heater via a return line.

4. The waste heat recovery system for thermal power plant exhaust steam according to claim 4, characterized in that: The dilute solution delivery pipeline and the return low-pressure heating pipeline exchange heat through a heat source water heat exchanger.

5. The waste heat recovery system for thermal power plant exhaust steam according to claim 1 or 4, characterized in that: The concentrated solution delivery pipeline and the dilute solution delivery pipeline exchange heat through a solution heat exchanger.

6. A method for recovering waste heat from exhaust steam in a thermal power plant using a heat pump, characterized in that, The waste heat recovery system for thermal power plant exhaust steam as described in any one of claims 1-5 includes the following steps: The exhaust steam from the turbine is directly introduced into the absorber as refrigerant steam; In the absorber, the exhaust steam reacts with the concentrated lithium bromide solution to generate a dilute lithium bromide solution and release heat, which is used to heat the secondary network return water flowing through it. A dilute lithium bromide solution is fed to a regenerator; in the regenerator, the dilute lithium bromide solution is heated by a driving heat source, causing it to release refrigerant vapor and concentrate into a concentrated lithium bromide solution; the concentrated lithium bromide solution is then fed back to the absorber for recycling. The refrigerant vapor generated by the regenerator is introduced into the condenser, where its condensation heat is released to the secondary network return water, and then discharged after condensation into water.

7. A method for recovering waste heat from thermal power plant exhaust steam using a heat pump according to claim 6, characterized in that, The driving heat source is extracted steam from the steam turbine.

8. A method for recovering waste heat from thermal power plant exhaust steam using a heat pump according to claim 6 or 7, characterized in that, Before the dilute lithium bromide solution enters the regenerator, it exchanges heat with the concentrated lithium bromide solution returning from the regenerator in a solution heat exchanger.

Images