A heat and power cogeneration system of a nuclear power unit with a large heat-to-electricity ratio and its working method

Abstract

The invention discloses a cogeneration system of a nuclear power unit with a large heat-to-electricity ratio and a working method thereof, comprising a reactor, a steam heat exchanger, an absorption heat pump and a heat network heater; the gas outlet of the reactor is connected to the hot end inlet of the steam heat exchanger, the hot end outlet of the steam heat exchanger is connected to the high-temperature heat source end inlet of the absorption heat pump, the high-temperature heat source end outlet of the absorption heat pump is connected to the hot end inlet of the heat network heater, the cold end of the heat network heater is connected to heat network water, the hot end outlet of the heat network heater is connected to the low-temperature heat source end inlet of the absorption heat pump, and the low-temperature heat source end outlet of the absorption heat pump is connected to the gas inlet of the reactor. The temperature of steam entering the reactor is reduced, and the thermal energy utilization efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power heating, and relates to a heat and power cogeneration system of a nuclear power unit with a large heat-to-power ratio and a working method thereof. Background Art

[0002] Nuclear power heating is a nuclear energy system that mainly outputs sensible heat. It can be used for heating and comprehensive utilization of urban residents. As a supplement to nuclear power, its promotion and application will help improve the energy structure, reduce greenhouse gas emissions and improve the urban environment. Nuclear power heating has good inherent safety, simple system, reliable operation, and can be built near densely populated areas, saving the expensive cost of long-distance sensible heat transportation.

[0003] However, nuclear power heating has not yet been widely used. It is mainly in the form of turbine steam extraction, and the thermal power is relatively small. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a nuclear power unit cogeneration system with a large heat-to-electricity ratio and its working method, so as to reduce the temperature of steam entering the reactor and improve the thermal energy utilization efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A heat and power cogeneration system for a nuclear power unit with a large heat-to-power ratio, comprising a reactor, a steam heat exchanger, an absorption heat pump and a heat network steam heat exchanger;

[0007] The gas outlet of the reactor is connected to the hot end inlet of the steam heat exchanger, the hot end outlet of the steam heat exchanger is connected to the high-temperature heat source inlet of the absorption heat pump, the high-temperature heat source outlet of the absorption heat pump is connected to the hot end inlet of the heat network steam heat exchanger, the cold end of the heat network steam heat exchanger is connected to heat network water, the hot end outlet of the heat network steam heat exchanger is connected to the low-temperature heat source inlet of the absorption heat pump, and the low-temperature heat source outlet of the absorption heat pump is connected to the gas inlet of the reactor.

[0008] Preferably, steam is arranged in the cold end of the steam heat exchanger, the cold end outlet of the steam heat exchanger is connected to the turbine inlet, the exhaust outlet of the turbine is connected to the hot end inlet of the condenser, and the hot end outlet of the condenser is connected to the cold end inlet of the steam heat exchanger.

[0009] Furthermore, a feedwater steam heat exchanger cold end is connected between the hot end outlet of the condenser and the cold end inlet of the steam heat exchanger, and a feedwater steam heat exchanger hot end inlet is connected to a steam extraction outlet of the turbine.

[0010] Preferably, the absorption heat pump includes a first heat exchanger, a second heat exchanger, an evaporator and an absorber; the high-temperature heat source end inlet of the first heat exchanger is connected to the hot end outlet of the steam heat exchanger, the high-temperature heat source end outlet of the first heat exchanger is connected to the hot end inlet of the heat network steam heat exchanger, and the refrigerant outlet of the first heat exchanger is connected to the hot end of the second heat exchanger, the cold end of the evaporator and the solution inlet of the absorber in sequence; the hot end outlet of the heat network steam heat exchanger is connected to the low-temperature heat source end inlet of the evaporator, and the low-temperature heat source end outlet of the evaporator is connected to the gas inlet of the reactor; the solution outlet of the first heat exchanger is connected to the solution inlet of the absorber, and the solution outlet of the absorber is connected to the solution inlet of the first heat exchanger.

[0011] Furthermore, the cold end inlet of the absorber is connected to a heat network return pipe, the cold end outlet of the absorber is connected to a cold end inlet of a second heat exchanger, and the cold end outlet of the second heat exchanger is connected to a heat network water supply pipe.

[0012] Furthermore, a flow valve is provided between the hot end of the second heat exchanger and the cold end of the evaporator.

[0013] Furthermore, a pressure pump is provided between the solution outlet of the absorber and the solution inlet of the first heat exchanger.

[0014] Furthermore, the solution in the absorption heat pump is a lithium bromide solution.

[0015] A method for operating a cogeneration system of a nuclear power unit with a large heat-to-electricity ratio based on any one of the above, comprising the following steps:

[0016] The high-temperature helium coming out of the reactor enters the hot end of the steam heat exchanger to heat the cold end of the steam heat exchanger. The helium at the outlet of the hot end of the steam heat exchanger enters the high-temperature heat source end of the absorption heat pump as the high-temperature heat source of the absorption heat pump. The helium at the outlet of the high-temperature heat source end enters the heat network steam heat exchanger to heat the heat network return water. The helium at the outlet of the heat network steam heat exchanger enters the low-temperature heat source end of the absorption heat pump as the low-temperature heat source of the absorption heat pump and then returns to the reactor to absorb heat.

[0017] Preferably, the high-temperature helium from the reactor enters the hot end of the steam heat exchanger to heat the steam at the cold end of the steam heat exchanger to generate high-temperature steam for driving the turbine to generate power. The exhaust steam of the turbine enters the condenser to condense, then enters the feed steam heat exchanger to be preheated by the turbine extraction steam, and then returns to the steam heat exchanger to be heated.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides heat by making full use of the heat of steam at the outlet of a steam heat exchanger of a nuclear power unit, and uses the steam at the outlet of the steam heat exchanger as both a high-temperature heat source and a low-temperature heat source of an absorption heat pump, thereby reducing the temperature of steam entering the reactor, achieving large temperature difference heating, improving the heating capacity of the nuclear power unit, and improving the heat-to-electricity ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0021] Among them: 1-reactor; 2-steam heat exchanger; 3-turbine; 4-condenser; 5-feedwater steam heat exchanger; 6-heat network steam heat exchanger; 7-first heat exchanger; 8-second heat exchanger; 9-evaporator; 10-absorber; 11-flow valve; 12-boosting pump. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0023] like Figure 1 As shown, the cogeneration system of a nuclear power unit with a large heat-to-electricity ratio according to the present invention includes a reactor 1, a steam heat exchanger 2, a turbine 3, a condenser 4, a feed steam heat exchanger 5, a heat network steam heat exchanger 6, a first heat exchanger 7, a second heat exchanger 8, an evaporator 9, an absorber 10, a flow valve 11 and a booster pump 12.

[0024] The gas outlet of the reactor 1 is connected to the hot end inlet of the steam heat exchanger 2, the hot end outlet of the steam heat exchanger 2 is connected to the high-temperature heat source end inlet of the absorption heat pump, the high-temperature heat source end outlet of the absorption heat pump is connected to the hot end inlet of the heat network steam heat exchanger 6, the cold end of the heat network steam heat exchanger 6 is connected to the heat network water, the hot end outlet of the heat network steam heat exchanger 6 is connected to the low-temperature heat source end inlet of the absorption heat pump, and the low-temperature heat source end outlet of the absorption heat pump is connected to the gas inlet of the reactor 1.

[0025] Steam is arranged in the cold end of the steam heat exchanger 2, the cold end outlet of the steam heat exchanger 2 is connected to the inlet of the turbine 3, the exhaust outlet of the turbine 3 is connected to the hot end inlet of the condenser 4, and the hot end outlet of the condenser 4 is connected to the cold end inlet of the steam heat exchanger 2. The cold end of the feedwater steam heat exchanger 5 is connected between the hot end outlet of the condenser 4 and the cold end inlet of the steam heat exchanger 2, and the hot end inlet of the feedwater steam heat exchanger 5 is connected to the extraction outlet of the turbine 3.

[0026] The absorption heat pump comprises a first heat exchanger 7, a second heat exchanger 8, an evaporator 9 and an absorber 10; the high temperature heat source end inlet of the first heat exchanger 7 is connected to the hot end outlet of the steam heat exchanger 2, the high temperature heat source end outlet of the first heat exchanger 7 is connected to the hot end inlet of the heat network steam heat exchanger 6, the refrigerant outlet of the first heat exchanger 7 is sequentially connected to the hot end of the second heat exchanger 8, the cold end of the evaporator 9 and the solution inlet of the absorber 10; the hot end outlet of the heat network steam heat exchanger 6 is connected to the low temperature heat source end inlet of the evaporator 9, the low temperature heat source end outlet of the evaporator 9 is connected to the gas inlet of the reactor 1; the solution outlet of the first heat exchanger 7 is connected to the solution inlet of the absorber 10, and the solution outlet of the absorber 10 is connected to the solution inlet of the first heat exchanger 7. The solution in the absorption heat pump is a lithium bromide solution.

[0027] The cold end inlet of the absorber 10 is connected to the heat network return pipe, the cold end outlet of the absorber 10 is connected to the cold end inlet of the second heat exchanger 8, and the cold end outlet of the second heat exchanger 8 is connected to the heat network water supply pipe.

[0028] A flow valve 11 is provided between the hot end of the second heat exchanger 8 and the cold end of the evaporator 9. A pressure pump 12 is provided between the solution outlet of the absorber 10 and the solution inlet of the first heat exchanger 7.

[0029] The high-temperature helium coming out of the reactor 1 enters the hot end of the steam heat exchanger 2 to heat the cold end of the steam heat exchanger 2. The steam at the outlet of the hot end of the steam heat exchanger 2 enters the high-temperature heat source end of the first heat exchanger 7 as a high-temperature heat source for the absorption heat pump. The helium at the outlet of the high-temperature heat source end enters the heat network steam heat exchanger 6 to heat the return water of the heat network. The helium at the outlet of the heat network steam heat exchanger 6 enters the low-temperature heat source end of the evaporator 9 as a low-temperature heat source for the absorption heat pump, and then returns to the reactor 1 to absorb heat.

[0030] The high-temperature helium coming out of the reactor 1 enters the hot end of the steam heat exchanger 2, heats the steam at the cold end of the steam heat exchanger 2, and generates high-temperature steam for driving the turbine 3 to generate power. The exhaust steam of the turbine 3 enters the condenser 4 to condense, and then enters the feed steam heat exchanger 5 to be preheated by the extraction steam of the turbine 3, and then returns to the steam heat exchanger 2 to be heated.

[0031] The working medium in the absorption heat pump includes the refrigerant for producing cold and the absorbent solution for absorbing and desorbing the refrigerant. The two constitute a working medium pair. The absorbent solution adopts a lithium bromide solution. The steam is used to heat the dilute solution with a certain concentration delivered from the absorber 10 by the booster pump 12 in the first heat exchanger 7, and most of the low-boiling refrigerant in the dilute solution is evaporated. The refrigerant vapor enters the hot end of the second heat exchanger 8, and is condensed into a refrigerant liquid by the cooling medium in the cold end of the second heat exchanger 8, and then reduced to the evaporation pressure through the flow valve 11. The refrigerant enters the cold end of the evaporator 9 through throttling, absorbs the heat in the cooling system, that is, the heat at the low-temperature heat source end of the evaporator 9, and is activated into a refrigerant vapor under the evaporation pressure. The concentrated solution remaining after the generation process in the first heat exchanger 7 enters the solution inlet of the absorber 10, mixes with the low-pressure refrigerant vapor coming out of the cold end outlet of the evaporator 9, absorbs the low-pressure refrigerant vapor and restores to the original concentration. The absorption process is often an exothermic process, so cooling water is required to cool the mixed solution in the absorber 10. The solution whose concentration has been restored in the absorber 10 is then pumped into the first heat exchanger 7 for further circulation after being pressurized by the solution pump 12.

[0032] The cold end of the absorber 10 is fed with return water from the heat network. After being heated by the solution end of the absorber 10, it enters the cold end of the second heat exchanger 8, where it is further heated by the hot end of the second heat exchanger 8 and then output as supply water for the heat network.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high heat-to-electricity ratio nuclear power unit cogeneration system, characterized in that: It includes a reactor (1), a steam heat exchanger (2), an absorption heat pump and a heat network steam heat exchanger (6); The gas outlet of the reactor (1) is connected to the hot end inlet of the steam heat exchanger (2), the hot end outlet of the steam heat exchanger (2) is connected to the high temperature heat source end inlet of the absorption heat pump, the high temperature heat source end outlet of the absorption heat pump is connected to the hot end inlet of the heat network steam heat exchanger (6), the cold end of the heat network steam heat exchanger (6) is connected to heat network water, the hot end outlet of the heat network steam heat exchanger (6) is connected to the low temperature heat source end inlet of the absorption heat pump, and the low temperature heat source end outlet of the absorption heat pump is connected to the gas inlet of the reactor (1); Steam is arranged in the cold end of the steam heat exchanger (2); the cold end outlet of the steam heat exchanger (2) is connected to the inlet of the turbine (3); the exhaust steam outlet of the turbine (3) is connected to the hot end inlet of the condenser (4); and the hot end outlet of the condenser (4) is connected to the cold end inlet of the steam heat exchanger (2); The cold end of a feedwater steam heat exchanger (5) is connected between the hot end outlet of the condenser (4) and the cold end inlet of the steam heat exchanger (2), and the hot end inlet of the feedwater steam heat exchanger (5) is connected to the steam extraction outlet of the turbine (3); The absorption heat pump comprises a first heat exchanger (7), a second heat exchanger (8), an evaporator (9) and an absorber (10); the high-temperature heat source end inlet of the first heat exchanger (7) is connected to the hot end outlet of the steam heat exchanger (2), the high-temperature heat source end outlet of the first heat exchanger (7) is connected to the hot end inlet of the heat network steam heat exchanger (6), the refrigerant outlet of the first heat exchanger (7) is connected in sequence to the hot end of the second heat exchanger (8), the cold end of the evaporator (9) and the solution inlet of the absorber (10); the hot end outlet of the heat network steam heat exchanger (6) is connected to the low-temperature heat source end inlet of the evaporator (9), and the low-temperature heat source end outlet of the evaporator (9) is connected to the gas inlet of the reactor (1); the solution outlet of the first heat exchanger (7) is connected to the solution inlet of the absorber (10), and the solution outlet of the absorber (10) is connected to the solution inlet of the first heat exchanger (7); The cold end inlet of the absorber (10) is connected to a heat network return pipe, the cold end outlet of the absorber (10) is connected to a cold end inlet of a second heat exchanger (8), and the cold end outlet of the second heat exchanger (8) is connected to a heat network water supply pipe.

2. The high heat-to-electricity ratio nuclear power unit cogeneration system according to claim 1 is characterized in that: A flow valve (11) is provided between the hot end of the second heat exchanger (8) and the cold end of the evaporator (9).

3. The high heat-to-electricity ratio nuclear power unit cogeneration system according to claim 1, characterized in that: A pressure pump (12) is provided between the solution outlet of the absorber (10) and the solution inlet of the first heat exchanger (7).

4. The high heat-to-electricity ratio nuclear power unit cogeneration system according to claim 1, characterized in that: The solution in the absorption heat pump is lithium bromide solution.

5. A method for operating a cogeneration system of a nuclear power unit with a large heat-to-electricity ratio according to any one of claims 1 to 4, characterized in that: The process includes: The high-temperature helium gas coming out of the reactor (1) enters the hot end of the steam heat exchanger (2) to heat the cold end of the steam heat exchanger (2); the helium gas at the hot end outlet of the steam heat exchanger (2) enters the high-temperature heat source end of the absorption heat pump to serve as the high-temperature heat source of the absorption heat pump; the helium gas at the high-temperature heat source end outlet enters the heat network steam heat exchanger (6) to heat the heat network return water; the helium gas at the heat network steam heat exchanger (6) outlet enters the low-temperature heat source end of the absorption heat pump to serve as the low-temperature heat source of the absorption heat pump, and then returns to the reactor (1) to absorb heat; The high-temperature helium gas from the reactor (1) enters the hot end of the steam heat exchanger (2) to heat the steam at the cold end of the steam heat exchanger (2), thereby generating high-temperature steam for driving the turbine (3) to generate power. The exhaust steam from the turbine (3) enters the condenser (4) to be condensed, then enters the feed steam heat exchanger (5) to be preheated by the extraction steam from the turbine (3), and then returns to the steam heat exchanger (2) to be heated.

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