JPH04309763A - Waste heat recovery apparatus for nuclear power plant - Google Patents

Abstract

PURPOSE:To enable the recovering of heat of a blow water of a steam evaporator discharged without being utilized sufficiently and heat of a thermal effluent of a condenser effectively at a nuclear power plant. CONSTITUTION:Blow water 11 from a steam generator 3 is flashed with a flash tank 14 to make a saturated steam 15, which is introduced into a reproducer 17 of a suction type heat pump and a thermal effluent 13 produced by cooling the steam with a condenser 8 is introduced into an absorption type heat pump evaporator 19. Both devices are used as drive heat source for an absorption type heat pump. Water 24 to be heated is introduced into an absorber 20 and then, into a condenser 18 of the absorption type heat pump to obtain a higher temperature hot water 24'.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery device for recovering exhaust heat from a nuclear power plant.

0002

2. Description of the Related Art FIG. 4 is a schematic diagram of a conventional pressurized water nuclear power plant. The primary cooling water 2 heated in the reactor 1 heats the secondary cooling water 4 in the steam generator 3 to become steam 5, and this steam 5 is supplied to the steam turbine 6 to drive the same steam turbine 6. do. Electric power is generated by a generator 7 directly connected to a steam turbine 6. steam turbine 6
The steam 5, which has been reduced in pressure by working in the condenser 8, is cooled by the cooling water 9 in the condenser 8 and is condensed and liquefied, and then returns to the steam generator 3 via the feed water heater 10 and the like. In steam generator 3,
Normally, a portion of the secondary cooling water is discharged outside for the purpose of water purification. This is called steam generator blow water (SG blow water). Further, in the feed water heater 10, the secondary cooling water 4 is preheated by the extracted air 12 from the steam turbine 6. Furthermore, although seawater is normally used as the cooling water 9 of the condenser 8, the temperature is raised by 5 to 10°C due to the heat of condensation of the water vapor 5, and then it is discharged into the sea as heated waste water 13.

0003

[Problems to be Solved by the Invention] The amount of heat radiated to the cooling water in the condenser is a huge amount, approximately 60% of the heat output of the steam generator, but the temperature of heated waste water is as low as 10 to 35 degrees Celsius. Because of this, the total amount of heat cannot be used effectively and is released into the ocean, which poses a problem in terms of energy efficiency.

On the other hand, the maximum temperature of blow water from steam generators has reached the level of 200°C, but conventionally it has been discharged as is or used to heat feed water, and has been thoroughly heated to near the ambient temperature. Utilization has not been measured, and there are still energy efficiency issues.

The present invention is an attempt to solve the above-mentioned problems in conventional nuclear power plants.

[0006]

[Means for Solving the Problems] The exhaust heat recovery device for a nuclear power plant of the present invention includes a flash tank, an evaporator, an absorber, and a condenser that flash blow water discharged from a steam generator to generate steam. and an absorption heat pump consisting of a regenerator, and a condenser that condenses low-pressure steam from a steam turbine using cooling water, and the steam generated in the flash tank is introduced to the regenerator as a heat source,
The heated waste water at the outlet of the condenser is introduced into the evaporator as a heat source, and the water to be heated is introduced into the absorber and then into the condenser.

[0007]

[Operation] In the present invention, high-temperature water vapor is obtained by flashing the high-temperature blow water discharged from the steam generator in a flash tank, and this is introduced into the regenerator of the absorption heat pump as a heat source for regeneration as described below. The dilute solution supplied from the absorption heat pump is heated to generate heat medium vapor, which is sent to the condenser of the absorption heat pump, and the dilute solution is concentrated.

On the other hand, the heated wastewater heated by exchanging heat with steam from the steam turbine in the condenser is introduced into the evaporator of the absorption heat pump as a heat source, and evaporates the heat medium liquid in the evaporator. This is sent to the absorber of the absorption heat pump, where it is absorbed by the concentrated solution sent from the regenerator to form a dilute solution, and the absorbed heat is radiated.

[0009] Water to be heated is introduced into the regenerator and condenser, and is heated by the absorbed heat in the regenerator and the heat medium vapor sent from the regenerator to the condenser, and is heated to a temperature higher than that of the heated waste water. Temperature water is obtained. Note that the heat transfer liquid condensed through heat exchange with water in the condenser is supplied to the evaporator.

[0010] In this way, in the present invention, the absorption type heat pump absorbs the energy of the heated waste water from the condenser and the blow water from the steam generator and heats the water. It is possible to obtain hot water with a higher temperature than heated wastewater.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained with reference to FIGS. 1 to 3. This embodiment relates to the exhaust heat recovery device of a nuclear power plant shown in FIG. 4, and the same parts are given the same reference numerals in FIG. Omitted.

In this embodiment, the blow water 1 of the steam generator 3
1 is flashed to become saturated steam 15, and part 1
A flash tank 14 is provided for discharging the water as a drain 16. 17, 18, 19, and 20 are a regenerator, a condenser, an evaporator, and an absorber, respectively forming an absorption heat pump. This absorption heat pump uses water as a heat medium and lithium bromide (LiBr) as an absorbent.
The medium is an aqueous solution of Saturated steam 15 from the flash tank 14 is introduced into the regenerator 17 to evaporate the dilute solution containing less lithium bromide in the regenerator 17. In addition, heated waste water 13 exiting the condenser 8
A part or all of it is introduced into the evaporator 19 and
The water inside is evaporated and supplied to the absorber 20. Furthermore, the water 24 to be heated is supplied to the absorber 2.
0, passes through the absorber 20, and is taken out through the upper condenser 18.

In this embodiment configured as described above, the dilute solution with a low concentration of lithium bromide in the regenerator 17 is
The blown water 11 of the steam generator 3 is flashed in the flash tank 14 and separated and heated by the saturated steam 15 of 0 to 10 kg/cm2G to evaporate the steam 23, which is supplied to the condenser 18, and the dilute solution is It is concentrated into a concentrated solution with a high concentration of lithium bromide, and this concentrated solution is supplied to the absorber 20. On the other hand, in the evaporator 19, water is heated by the heated waste water 13 to generate low-pressure steam 26, which is supplied to the absorber 20, and through this heat exchange, the temperature of the heated waste water 13 leaving the evaporator 19 is lowered. .

The absorber 20 is supplied with the low pressure steam 26 generated in the evaporator 19 and the concentrated solution from the regenerator 17, where the concentrated solution absorbs the low pressure steam 26 and becomes a dilute solution. , absorbed heat is released.

Water 25 to be heated is introduced into the absorber 20 and heated by the heat of absorption, and then introduced into the condenser 18, where it is heated by the water vapor 23, and from the condenser 18, high temperature hot water is extracted. 24'.

Steam 23 heated by water 25 in condenser 18
is condensed and becomes water 25 and is supplied to the evaporator 19, and
The dilute solution that has absorbed low-pressure water vapor 26 in the absorber 20 is supplied to the regenerator 17 .

The absorption heat pump in this embodiment described above uses a lithium bromide aqueous solution and water as media,
The operation diagram is shown in FIG. 2. a, b, c, and d indicate the states of the evaporator 19, absorber 20, condenser 18, and regenerator 17, respectively, and e, f, and g indicate the states of a dilute solution with a low lithium bromide content and a lithium bromide content, respectively. h indicates the movement of the concentrated solution and water, and h indicates the state of the water 24 through the absorber and condenser. When a lithium bromide aqueous solution is cooled, its equilibrium pressure decreases, and it has the property of absorbing water vapor at a slightly higher pressure. Higher than saturation temperature. This temperature difference varies depending on the lithium bromide concentration of the aqueous solution, but is generally 30 to 50°C.

Due to this property, as mentioned above, when heated waste water (temperature TC1) is used, evaporator 19 (temperature TE, pressure P
When the water in E) is evaporated, it is absorbed into a concentrated solution in the absorber 20, and the absorbed heat is radiated to heat and raise the temperature of the water 24 (temperature TH1). On the other hand, the dilute solution that has absorbed water vapor in the absorber 20 is supplied to the regenerator 17, where the blown water 11
The dilute solution is heated by the saturated steam 15 (temperature TS) obtained by flashing it in the flash tank 14, and the water evaporates to become a concentrated solution, which is returned to the absorber 20. The water vapor 23 generated in the regenerator 17 is supplied to the condenser 18, where water 24 is heated to be condensed. The temperature TC of the condenser 18 is changed to water 2
By setting the relationship between the temperatures TH1 and 4 as TC > TH1, the water 24 is heated not only in the absorber 20 but also in the condenser 18 by the heat of condensation of the saturated steam 15 to the temperature TH2 (TH2 < TC ). The temperature is raised. That is, by using an absorption heat pump, heated waste water 1 at a temperature TC1 is
It is possible to obtain hot water 24' with a temperature TH2 higher than 3.

In this embodiment, the relationship between the temperature of the water 24 supplied to the absorption heat pump and the supply steam pressure required to be supplied to the regenerator in order to obtain a predetermined outlet temperature of the hot water 24' is shown in FIG. show. The pressure of the blow water of the steam generator is usually 50 to 60 kg/cm2G, so 20 to 3
It can be seen that saturated steam with a required steam pressure of 1 to 6 kg/cm2G to convert water at 0°C to hot water at a temperature of 70 to 80°C can be sufficiently supplied.

As explained above, in this embodiment, heated waste water 1 from a low-temperature condenser having a temperature of usually 10 to 35°C is used.
3, by recovering the heat of the blow water 11 of the high-temperature steam generator, which has not been sufficiently utilized in the past, using an absorption heat pump and heating the water, hot water with a temperature significantly higher than that of the warm waste water 13 is generated. 24' can be obtained, and energy efficiency can be improved. In addition, the temperature of the heated waste water 13 is lowered before it is discharged, resulting in an environmentally favorable state.

Incidentally, 50 to 70 obtained in this example
Hot water at a temperature level of 70°C can be used for space heating, process heating, hot water supply, etc. Hot water at a temperature level of 70 to 80°C can be used as a driving heat source for an absorption chiller for cooling, process cooling, etc. can be used.

[0022]

[Effects of the Invention] The present invention can achieve the following effects.

(1) An absorption heat pump that uses the blow water of the steam generator and the heated waste water from the condenser outlet as driving heat sources recovers heat from the blow water and heated waste water, and generates utility value at a higher temperature than the heated waste water. It is possible to obtain hot water with a high temperature, and a part of the heat of the heated waste water that was conventionally discharged into the sea etc. and the heat of the blow water of the steam generator can be effectively used, which is beneficial in terms of energy efficiency.

(2) The heated waste water at the condenser outlet acts as a heat source in the evaporator of the absorption heat pump and is itself cooled, so the temperature level discharged into the sea etc. is lowered and the environmental impact can be reduced. .

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is an operation diagram of the absorption heat pump in the same embodiment.

FIG. 3 is a graph showing the relationship between hot water temperature and supplied steam pressure in the same example.

FIG. 4 is a system diagram of a conventional nuclear power plant.

[Explanation of symbols]

1 Nuclear reactor 2 Primary cooling water 3 Steam generator 4 Secondary cooling water 5 Water vapor 6 Steam turbine 7 Generator 8 Condenser 9 Cooling water 10 Water supply heater 11 Steam generator blow water 12 Bleed air 13 Heated wastewater 14 Flash tank 15 Saturated steam 16 Drain 17 Absorption heat pump regenerator 18 Absorption heat pump condenser 19 Absorption heat pump evaporator 20 Absorption heat pump absorber 23 Water vapor 24 Water to be heated 24′ hot water 26 Low pressure water vapor

Claims (1)

[Claims] Claim 1: An absorption heat pump consisting of a flash tank, an evaporator, an absorber, a condenser, and a regenerator that generate steam by flashing blow water discharged from a steam generator, and an absorption heat pump that generates steam by flushing blow water discharged from a steam generator. It is equipped with a condenser that condenses low-pressure steam, the steam generated in the flash tank is introduced into the regenerator as a heat source, and the heated waste water at the outlet of the condenser is introduced into the evaporator as a heat source and is heated. An exhaust heat recovery device for a nuclear power plant, characterized in that water is introduced into an absorber and then into a condenser.