Nuclear power unit warm water discharge waste heat utilization system and method

Abstract

This invention discloses a waste heat recovery system for warm wastewater from a nuclear power unit, comprising a warm wastewater cooling and discharge module, a steam power generation module, and a cold seawater cooling module. The warm wastewater cooling and discharge module is used for cooling and discharging the warm wastewater; the steam power generation module is used for steam power generation; the cold seawater cooling module is used for condensing the steam from the steam power generation module; the warm wastewater cooling and discharge module and the steam power generation module are thermally coupled at the evaporator of the power generation loop; the steam power generation module and the cold seawater cooling module are thermally coupled at the condenser of the power generation loop. In this invention, a closed-loop power generation loop is added to the outlet of the secondary loop circulating water system of the nuclear power unit. A circulating water pump pumps high-temperature water from the outlet into the evaporator to heat the working fluid in the closed-loop power generation loop into steam, which then enters the turbine to generate electricity. The exhaust steam is cooled by low-temperature seawater in the condenser and then circulated through a working fluid circulation pump, thus realizing waste heat recovery and improving the economic efficiency of power generation.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power waste heat utilization technology, specifically relating to a system and method for utilizing waste heat from thermal wastewater from nuclear power units. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, all operating and under-construction nuclear power units in my country are coastal nuclear power units. These units mainly consist of a nuclear reactor, a primary loop system, a secondary loop system, and other auxiliary systems. The secondary loop system converts the thermal energy of steam into electrical energy. It comprises a steam-water separator, a turbine, a condenser, condensate pumps, and feedwater pumps. The feedwater in the secondary loop absorbs heat from the primary loop, becoming steam, which then enters the turbine to perform work, driving the generator to produce electricity. The steam after performing work enters the condenser, condenses into water, and is then pumped to the heater. After being heated, the water returns to the steam generator, forming a closed loop in the secondary loop. The secondary loop system generates a large amount of warm wastewater. Directly discharging this warm wastewater not only wastes a significant amount of residual heat but also causes thermal pollution due to its higher temperature than the surrounding seawater, negatively impacting the environment. Therefore, how to handle the warm wastewater generated in the secondary loop system has attracted increasing attention. Summary of the Invention

[0004] To overcome the above problems, this invention provides a system and method for utilizing waste heat from wastewater discharge in nuclear power units. This invention adds a closed-loop power generation loop at the outlet of the secondary loop circulating water system of the nuclear power unit. A circulating water pump pumps the high-temperature water from the outlet into an evaporator to heat the working fluid in the closed-loop power generation loop into steam. This steam then enters the turbine to generate electricity. The exhaust steam is cooled by low-temperature seawater in the condenser and then circulated again by the working fluid circulation pump, thus realizing waste heat utilization and improving the economic efficiency of power generation.

[0005] In a first aspect, the present invention provides a waste heat recovery system for warm wastewater from a nuclear power unit, the system comprising a warm wastewater cooling and discharge module, a steam power generation module, and a cold seawater cooling module;

[0006] The warm wastewater cooling and discharge module is used for cooling and discharging warm wastewater; the warm wastewater cooling and discharge module includes a condenser, which is connected to the evaporator of the power generation circuit, and the evaporator of the power generation circuit is connected to the mixing pipe of warm wastewater and cold seawater.

[0007] The steam power generation module is used for steam power generation; the steam power generation module includes a power generation circuit evaporator, which is connected to a power generation circuit turbine generator set, and the power generation circuit turbine generator set is connected to a power generation circuit condenser.

[0008] The cold seawater cooling module is used for condensing steam from the steam power generation module; the cold seawater cooling module includes a cold seawater pipe, which is connected to the condenser of the power generation circuit via a cold seawater pump; the condenser of the power generation circuit is connected to a warm water drainage and cold seawater mixing pipe.

[0009] The thermally coupled heat-dissipating drainage module and the steam power generation module are thermally coupled at the evaporator of the power generation circuit; the thermally coupled heat-dissipating module and the cold seawater cooling module are thermally coupled at the condenser of the power generation circuit.

[0010] A second aspect of the present invention provides a method for utilizing waste heat from thermal wastewater from a nuclear power unit, the method comprising:

[0011] (1) The warm wastewater generated by the condenser in the secondary loop circulating water system of the nuclear power unit is thermally coupled with the working fluid in the evaporator of the power generation loop.

[0012] (2) After absorbing heat, the working fluid is heated into steam in the evaporator of the power generation circuit, and then enters the steam turbine generator set of the power generation circuit to drive the steam turbine to generate electricity; after the power generation is completed, the working fluid enters the condenser of the power generation circuit to be condensed by cold seawater.

[0013] (3) The warm water that has cooled down after thermal coupling in step (1) is mixed with the cold seawater that has been condensed in step (2) and then discharged.

[0014] The beneficial effects of this invention are:

[0015] (1) In this invention, a closed-loop power generation circuit is added to the outlet of the secondary loop circulating water system of the nuclear power unit. The high-temperature water at the outlet is pumped into the evaporator by the circulating water pump to heat the working fluid of the closed-loop power generation circuit into steam, which enters the steam turbine to generate electricity. The exhaust steam is cooled by low-temperature seawater in the condenser and then circulated through the working fluid circulation pump, thereby realizing the utilization of waste heat and improving the economic efficiency of power generation.

[0016] (2) In this invention, cold seawater is drawn from the deep ocean, mixed with warm water in the evaporator after passing through the condenser, and then discharged into the sea, which further reduces the temperature of the warm water.

[0017] (3) In hot weather, the mixed wastewater can be switched as the cooling water source for the nuclear island plant water system, solving the problem that the inlet water temperature of the nuclear island plant water system exceeds the design benchmark, and ensuring the safety and economy of the nuclear power unit operation. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0019] Figure 1 This is a simplified flow chart of the nuclear power unit waste heat recovery system of the present invention.

[0020] Among them, 1-steam turbine generator set; 2-steam turbine exhaust pipe; 3-condenser; 4-condensate pipe; 5-circulating water inlet; 6-circulating water pump; 7-circulating water outlet; 8-circulating water outlet isolation valve; 9-warm water pipe; 10-warm water isolation valve; 11-generator circuit evaporator; 12-warm water and cold seawater mixing pipe; 13-warm water and cold seawater mixing pipe isolation valve; 14-discharge pipe; 15-cold seawater pipe; 16-cold seawater pump; 17-... - Generator circuit condenser; 18- Warm water drainage and cold seawater mixing pipe branch; 19- Warm water drainage and cold seawater mixing pipe branch isolation valve; 20- Nuclear island plant water inlet pipe; 21- Nuclear island plant water inlet pipe isolation valve; 22- Nuclear island plant water pump; 23- Nuclear island plant water supply pipe; 24- Generator circuit steam pipe; 25- Generator circuit steam turbine generator set; 26- Generator circuit steam turbine exhaust pipe; 27- Generator circuit condensate pipe; 28- Working fluid circulation pump. Detailed Implementation

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] A first typical embodiment of the present invention provides a waste heat utilization system for warm wastewater from a nuclear power unit, the system comprising a warm wastewater cooling and discharge module, a steam power generation module, and a cold seawater cooling module;

[0024] The warm wastewater cooling and discharge module is used for cooling and discharging warm wastewater; the warm wastewater cooling and discharge module includes a condenser, which is connected to the evaporator of the power generation circuit, and the evaporator of the power generation circuit is connected to the mixing pipe of warm wastewater and cold seawater.

[0025] The steam power generation module is used for steam power generation; the steam power generation module includes a power generation circuit evaporator, which is connected to a power generation circuit turbine generator set, and the power generation circuit turbine generator set is connected to a power generation circuit condenser.

[0026] The cold seawater cooling module is used for condensing steam from the steam power generation module; the cold seawater cooling module includes a cold seawater pipe, which is connected to the condenser of the power generation circuit via a cold seawater pump; the condenser of the power generation circuit is connected to a warm water drainage and cold seawater mixing pipe.

[0027] The thermally coupled heat-dissipating drainage module and the steam power generation module are thermally coupled at the evaporator of the power generation circuit; the thermally coupled heat-dissipating module and the cold seawater cooling module are thermally coupled at the condenser of the power generation circuit.

[0028] In one or more embodiments, the system further includes a cooling water source module for the nuclear island plant water system, which is used for cooling the nuclear island plant water system under high temperature conditions; the cooling water source module for the nuclear island plant water system includes a branch pipe for mixing warm drainage and cold seawater, which is connected to the nuclear island plant water supply pipe through a nuclear island plant water pump.

[0029] Preferably, the branch pipe for mixing warm water and cold seawater is connected to the water pump of the nuclear island plant via a branch pipe isolation valve for mixing warm water and cold seawater.

[0030] In one or more embodiments, in the temperature drainage cooling and discharge module, the condenser is connected to the circulating water inlet via a circulating water pump.

[0031] Preferably, the circulating water inlet is connected to the nuclear island plant water inlet pipe isolation valve through the nuclear island plant water inlet pipe, and the nuclear island plant water inlet pipe isolation valve is connected to the nuclear island plant water pump.

[0032] In one or more embodiments, in the temperature drainage cooling and discharge module, the condenser is connected to the circulating water outlet; the circulating water outlet is connected to the temperature drainage isolation valve through the temperature drainage pipe; and the temperature drainage isolation valve is connected to the evaporator of the power generation circuit.

[0033] In one or more embodiments, in the temperature drainage cooling and discharge module, the condenser is connected to the steam turbine generator set through the steam turbine exhaust pipe; the condenser is also connected to the condensate pipe.

[0034] In one or more embodiments, in the steam power generation module, the power generation circuit evaporator is connected to the power generation circuit turbine generator set via the power generation circuit steam pipe.

[0035] In one or more embodiments, in the steam power generation module, the power generation circuit turbine generator set is connected to the power generation circuit condenser through the power generation circuit turbine exhaust pipe.

[0036] In one or more embodiments, in the steam power generation module, the power generation circuit condenser is connected to the working fluid circulation pump via a power generation circuit condensate pipe, and the working fluid circulation pump is connected to the power generation circuit evaporator. The working fluid condensed by the power generation circuit condenser is then recycled back into the power generation circuit evaporator via the working fluid circulation pump.

[0037] In one or more embodiments, the warm water drainage and cold seawater mixing pipe is connected to the discharge pipe via a warm water drainage and cold seawater mixing pipe isolation valve.

[0038] Preferably, the warm water drainage and cold seawater mixing pipe is connected to a branch pipe of the warm water drainage and cold seawater mixing pipe.

[0039] In one or more embodiments, when the closed-loop power generation circuit needs maintenance or malfunctions, the warm water discharge isolation valve and the warm water discharge and cold seawater mixing pipe isolation valve are closed, the circulating water outlet isolation valve is opened, the cold seawater pump and the working fluid circulation pump are stopped, and the seawater enters the condenser through the circulating water inlet. After absorbing heat, the seawater is discharged into the sea through the circulating water outlet and the discharge pipe to maintain the normal operation of the unit.

[0040] A second typical embodiment of the present invention provides a method for utilizing waste heat from thermal wastewater from a nuclear power unit, the method comprising:

[0041] (1) The warm wastewater generated by the condenser in the secondary loop circulating water system of the nuclear power unit is thermally coupled with the working fluid in the evaporator of the power generation loop.

[0042] (2) After absorbing heat, the working fluid is heated into steam in the evaporator of the power generation circuit, and then enters the steam turbine generator set of the power generation circuit to drive the steam turbine to generate electricity; after the power generation is completed, the working fluid enters the condenser of the power generation circuit to be condensed by cold seawater.

[0043] (3) The warm water that has cooled down after thermal coupling in step (1) is mixed with the cold seawater that has been condensed in step (2) and then discharged.

[0044] In one or more embodiments, in step (2), the condensed working fluid is pumped back into the evaporator of the power generation circuit for recycling via a working fluid circulation pump.

[0045] In one or more embodiments, in step (3), the warm wastewater is mixed with cold seawater and then enters the nuclear island plant water supply pipe through the nuclear island plant water pump, which can be used as a cooling water source for the nuclear island plant water system in hot weather.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] like Figure 1 The system shown is a waste heat recovery system for warm wastewater from a nuclear power unit. The system includes a warm wastewater cooling and discharge module, a steam power generation module, a cold seawater cooling module, and a cooling water source module for the nuclear island plant water system.

[0049] The temperature-controlled wastewater cooling and discharge module is used for cooling and discharging temperature-controlled wastewater from the secondary loop circulating water system of a nuclear power unit. The module includes a condenser connected to the circulating water outlet. The circulating water outlet is connected to a temperature-controlled wastewater isolation valve via a temperature-controlled wastewater pipe. The temperature-controlled wastewater isolation valve is connected to the evaporator in the power generation loop. The condenser is connected to the turbine generator unit via a turbine exhaust pipe. The condenser is also connected to a condensate pipe. The condenser is connected to the circulating water inlet via a circulating water pump.

[0050] The steam power generation module is used to generate electricity after the working fluid absorbs heat. The module includes a power generation circuit evaporator, which is connected to a power generation circuit turbine generator set via a power generation circuit steam pipe. The power generation circuit turbine generator set is connected to a power generation circuit condenser via a power generation circuit turbine exhaust pipe. The power generation circuit condenser is connected to a working fluid circulation pump via a power generation circuit condensate pipe, and the working fluid circulation pump is connected to the power generation circuit evaporator. The working fluid condensed by the power generation circuit condenser is then recycled back into the power generation circuit evaporator via the working fluid circulation pump.

[0051] The cold seawater cooling module is used for condensing steam from the steam power generation module; the cold seawater cooling module includes a cold seawater pipe, which is connected to the condenser of the power generation circuit via a cold seawater pump.

[0052] The evaporator and condenser of the power generation circuit are both connected via a warm water drainage and a cold seawater mixing pipe, which is connected to the discharge pipe via a warm water drainage and cold seawater mixing pipe isolation valve. The warm water drainage and cold seawater mixing pipe is also connected to a branch pipe of the warm water drainage and cold seawater mixing pipe.

[0053] When the closed-loop power generation circuit needs maintenance or malfunctions, close the warm water discharge isolation valve and the warm water discharge and cold seawater mixing pipe isolation valve, open the circulating water outlet isolation valve, stop the cold seawater pump and the working fluid circulation pump, and the seawater enters the condenser through the circulating water inlet. After absorbing heat, it is discharged into the sea through the circulating water outlet and the discharge pipe to maintain the normal operation of the unit.

Claims

1. A waste heat recovery system for thermal wastewater from a nuclear power unit, characterized in that, The system includes a warm water cooling and discharge module, a steam power generation module, and a cold seawater cooling module; The warm wastewater cooling and discharge module is used for cooling and discharging warm wastewater; the warm wastewater cooling and discharge module includes a condenser, which is connected to the evaporator of the power generation circuit, and the evaporator of the power generation circuit is connected to the mixing pipe of warm wastewater and cold seawater. The steam power generation module is used for steam power generation; the steam power generation module includes a power generation circuit evaporator, which is connected to a power generation circuit turbine generator set, and the power generation circuit turbine generator set is connected to a power generation circuit condenser. The cold seawater cooling module is used for condensing steam from the steam power generation module; the cold seawater cooling module includes a cold seawater pipe, which is connected to the condenser of the power generation circuit via a cold seawater pump; the condenser of the power generation circuit is connected to a warm water drainage and cold seawater mixing pipe. The warm water cooling and discharge module and the steam power generation module are thermally coupled at the evaporator of the power generation circuit; the steam power generation module and the cold seawater cooling module are thermally coupled at the condenser of the power generation circuit. The system includes a cooling water source module for the nuclear island plant water system, which is used for cooling the nuclear island plant water system under high temperature weather conditions; the cooling water source module for the nuclear island plant water system includes a branch pipe for mixing warm drainage and cold seawater, which is connected to the nuclear island plant water supply pipe through a nuclear island plant water pump. In the aforementioned temperature drainage cooling and discharge module, the condenser is connected to the circulating water inlet via a circulating water pump; the circulating water inlet is connected to the nuclear island plant water inlet pipe isolation valve via the nuclear island plant water inlet pipe, and the nuclear island plant water inlet pipe isolation valve is connected to the nuclear island plant water pump. In the temperature-controlled drainage cooling and discharge module, the condenser is connected to the circulating water outlet; the circulating water outlet is connected to the temperature-controlled drainage isolation valve through the temperature-controlled drainage pipe; the temperature-controlled drainage isolation valve is connected to the evaporator of the power generation circuit; the condenser is connected to the steam turbine generator set through the steam turbine exhaust pipe; and the condenser is connected to the condensate pipe. The warm water and cold seawater mixing pipe is connected to the discharge pipe through a warm water and cold seawater mixing pipe isolation valve; the warm water and cold seawater mixing pipe is connected to a branch pipe of the warm water and cold seawater mixing pipe.

2. The nuclear power unit waste heat recovery system as described in claim 1, characterized in that, The branch pipe for the mixing of warm water and cold seawater is connected to the water pump of the nuclear island plant through the isolation valve of the branch pipe for the mixing of warm water and cold seawater.

3. The nuclear power unit waste heat recovery system as described in claim 1, characterized in that, In the steam power generation module, the power generation circuit evaporator is connected to the power generation circuit turbine generator set through the power generation circuit steam pipe; The generator set of the power generation circuit turbine is connected to the power generation circuit condenser through the exhaust pipe of the power generation circuit turbine.

4. The nuclear power unit waste heat recovery system as described in claim 1, characterized in that, In the steam power generation module, the power generation circuit condenser is connected to the working fluid circulation pump via the power generation circuit condensate pipe, and the working fluid circulation pump is connected to the power generation circuit evaporator.

5. A method for utilizing waste heat from thermal wastewater from a nuclear power unit, characterized in that, The waste heat recovery system of the nuclear power unit as described in any one of claims 1-4 is adopted; The method includes: (1) The warm water from the secondary loop circulating water system of the nuclear power unit generated by the condenser is thermally coupled with the working fluid in the evaporator of the power generation loop; (2) The working fluid, after absorbing heat, is heated into steam in the evaporator of the power generation circuit, and then enters the steam turbine generator set of the power generation circuit to drive the steam turbine to generate electricity; after the power generation is completed, the working fluid enters the condenser of the power generation circuit to be condensed by cold seawater. (3) The warm water that has cooled down after thermal coupling in step (1) is mixed with the cold seawater that has been condensed in step (2) and then discharged.

6. The method as described in claim 5, characterized in that, In step (2), the condensed working fluid is pumped back into the evaporator of the power generation circuit for recycling via a working fluid circulation pump. In step (3), the warm wastewater is mixed with cold seawater and then pumped into the nuclear island plant water supply pipe through the nuclear island plant water pump to serve as the cooling water source for the nuclear island plant water system in hot weather.

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