CN115274150B - Two-loop waste heat discharging system and method based on concentrated seawater cooling - Google Patents
Two-loop waste heat discharging system and method based on concentrated seawater cooling Download PDFInfo
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- CN115274150B CN115274150B CN202210939097.7A CN202210939097A CN115274150B CN 115274150 B CN115274150 B CN 115274150B CN 202210939097 A CN202210939097 A CN 202210939097A CN 115274150 B CN115274150 B CN 115274150B
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- 239000002918 waste heat Substances 0.000 title claims abstract description 68
- 238000001816 cooling Methods 0.000 title claims abstract description 62
- 238000007599 discharging Methods 0.000 title claims abstract description 51
- 239000013535 sea water Substances 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000002955 isolation Methods 0.000 claims description 70
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 43
- 239000000498 cooling water Substances 0.000 claims description 19
- 230000001105 regulatory effect Effects 0.000 claims description 10
- 238000011144 upstream manufacturing Methods 0.000 claims description 9
- 239000013505 freshwater Substances 0.000 claims description 4
- 230000020169 heat generation Effects 0.000 claims description 2
- 230000008859 change Effects 0.000 abstract description 2
- 239000000941 radioactive substance Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 239000002826 coolant Substances 0.000 description 3
- 230000004992 fission Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000008642 heat stress Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
- G21C15/18—Emergency cooling arrangements; Removing shut-down heat
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
- G21C15/18—Emergency cooling arrangements; Removing shut-down heat
- G21C15/182—Emergency cooling arrangements; Removing shut-down heat comprising powered means, e.g. pumps
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Structure Of Emergency Protection For Nuclear Reactors (AREA)
Abstract
The invention discloses a secondary loop waste heat discharging system and method of a marine nuclear power device based on concentrated seawater cooling, which are used as a safety system capable of automatically putting into operation and effectively guiding out core waste heat under normal and accident shutdown working conditions of a reactor and have the advantages of high heat exchange efficiency, less change of the existing equipment, small space requirement and the like. Based on the technical characteristics of the novel integrated two-loop system, an active waste heat discharging channel based on the secondary side of the steam generator and the concentrated seawater cooling system is newly constructed, so that the configuration multiple and diversity of the waste heat discharging system can be further expanded, and the purpose of further improving the safety and reliability of the waste heat discharging function of the marine nuclear power device is achieved.
Description
Technical Field
The invention relates to the technical field of nuclear reactor system design, in particular to a secondary loop active waste heat discharging system and method of a marine nuclear power device, and especially relates to a secondary loop active waste heat discharging system of a marine nuclear power device based on concentrated seawater cooling.
Background
After the nuclear power plant for the ship is normally or accident shutdown, a great amount of residual heat release (simply called waste heat) can be generated in the reactor core within a quite long time after shutdown due to delayed neutron fission, decay of fission products and neutron capture products and the like. In any case, the marine nuclear power plant is required to safely and reliably lead out the waste heat of the reactor core, reduce the temperature and the pressure of the reactor and a loop system according to a certain speed, and ensure that the time of the reactor core is within the range of thermal safety standards. The waste heat discharging function is critical to the nuclear safety of the device, and the waste heat discharging system is required to have high safety and reliability. Currently, marine nuclear power plants mainly employ a configuration scheme of a loop active waste heat removal system. Besides the risks of failure, human failure and the like caused by depending on the active equipment, the active waste heat discharging system of the loop also increases the probability of pipeline rupture and coolant loss of the nuclear power device caused by the closed connection with the main pipeline of the loop, namely increases the risk of radioactive substance release. The invention provides a secondary loop active waste heat discharging system of a marine nuclear power device based on concentrated seawater cooling based on the technical characteristics of a novel integrated secondary loop system by utilizing the characteristic that a waste heat discharging function after shutdown of the marine nuclear power device and a secondary loop device cooling function during operation are not overlapped in time sequence.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the primary loop active waste heat discharging system adopted by the existing marine nuclear power device is connected with a primary loop pipeline in a closed mode, so that the probability of pipeline cracking and coolant loss of the nuclear power device is increased, and the risk of radioactive substance release is increased. The invention provides a secondary loop active waste heat discharging system and method for a marine nuclear power device, which can effectively solve the problems: after the marine power device is normally or in accident shutdown, the active waste heat discharging system of the steam generator secondary side and the concentrated seawater cooling system is constructed to guide the waste heat of the reactor core into the final hot-trap seawater, so that the long-term cooling of the reactor core is effectively realized. On one hand, the newly constructed two-loop active waste heat discharging system integrates and shares the existing equipment (namely, directly utilizes the existing concentrated heat exchanger and does not need to newly add a heat exchanger), thereby being beneficial to reducing the volume and the weight of the marine nuclear power plant; on the other hand, the configuration multiple and diversity of the waste heat discharging system are further expanded, and the safety and reliability of the waste heat discharging function of the marine nuclear power device are further improved.
The invention is realized by the following technical scheme:
A secondary circuit waste heat discharging system based on concentrated seawater cooling comprises a part of steam pipeline and water supply pipeline of the secondary circuit system, a seawater cooling circuit and a concentrated heat exchanger, wherein the concentrated heat exchanger is used for bearing the secondary circuit steam cooling function; the heat exchanger also comprises a steam connecting pipe and a condensate connecting pipe, wherein the input end of the steam connecting pipe is connected with a steam pipeline of the two-loop system, the output end of the steam connecting pipe is connected with the input end of the inner pipe side of the concentrated heat exchanger, the input end of the condensate connecting pipe is connected with the output end of the inner pipe side of the centralized heat exchanger, and the output end of the condensate connecting pipe is connected with a water supply pipeline of the two-loop system; the system also comprises an isolation valve I, an isolation valve II, an isolation valve III, an isolation valve IV, an isolation valve V, an isolation valve VI and a condensate water transfer pump; the isolation valve I is arranged on a steam pipeline leading to the steam turbine and is positioned downstream of the steam connecting pipe access point; the isolation valve II is arranged on a water supply pipeline leading from the condenser to the steam generator and is positioned at the upstream of the condensate pipe access point; the isolation valve III and the isolation valve IV are respectively arranged at the input end and the output end of the equipment cooling water loop; the isolation valve V is arranged on the steam connecting pipe, and the condensed water transfer pump and the isolation valve VI are both arranged on the condensed water connecting pipe.
The invention is essentially a marine nuclear power plant secondary loop active waste heat discharging system and method based on a concentrated seawater cooling system, and the basic working principle is as follows:
The invention combines the overall design characteristics of the integrated two-loop system, and only needs to newly construct a steam cooling channel between the secondary side of the steam generator and the concentrated heat exchanger on the basis of the scheme of the concentrated seawater cooling system. Wherein the concentrated heat exchanger, the seawater cooling loop, etc. are by means of a concentrated seawater cooling system. The main newly-added equipment of the secondary side active waste heat discharging system of the steam generator only comprises: steam connection pipe, condensed water connection pipe, lightering pump, isolating valve and check valve.
During normal operation of the nuclear power plant, the centralized heat exchanger is isolated from the secondary side of the steam generator, and the centralized heat exchanger bears the cooling function of the two-loop system equipment.
After the reactor is shut down, the system equipment which can normally run only by cooling provided by the centralized heat exchanger in the second loop stops running and does not need to be cooled. Firstly, a cooling water loop of equipment formed by a concentrated heat exchanger and a cooling user of a two-loop system is closed, and the connection between a steam generator, a steam turbine generator and a condenser is disconnected; and secondly, opening a cooling channel between the concentrated heat exchanger and the secondary side of the steam generator. The reactor core waste heat is firstly transferred to the secondary side of the steam generator through a reactor coolant system, steam generated after the secondary side supplies water to absorb heat is transferred to a centralized heat exchanger and condensed therein, and the condensed water returns to the secondary side of the steam generator through a condensed water transfer pump, so that a steam-water circulation loop of the secondary side of the steam generator, which returns to the centralized heat exchanger, is formed; the heat generated by condensing the steam in the concentrated heat exchanger is led out to the ocean heat trap through the seawater cooling loop flowing through the shell side, so that the purposes of leading out the core waste heat and ensuring the thermal safety of the reactor are achieved.
Further preferably, the condensate pipe is also provided with a regulating valve.
Further preferably, a check valve is further arranged on the condensate pipe, and the check valve is positioned downstream of the condensate pump.
Further preferably, the main equipment of the two-circuit system comprises a steam generator, a steam turbine and a condenser; the steam generator is connected with a steam turbine through a steam pipeline, the last-stage blade of the low-pressure cylinder of the steam turbine is directly connected with a condenser, and the condenser is connected with the steam generator through a water supply pipeline; the isolation valve I is positioned at the upstream of the steam turbine, and the isolation valve II is positioned at the downstream of the condenser.
Further preferably, the seawater cooling loop further comprises a marine heat trap, and an output end and an input end of the marine heat trap are respectively connected with an input end and an output end of the shell side of the centralized heat exchanger through pipelines.
Further preferably, the output end of the steam connecting pipe and the equipment cooling water loop at the downstream of the isolation valve V is connected with the input end of a first three-way pipe fitting, and the output end of the first three-way pipe fitting is connected to the input end of the pipe side of the concentrated heat exchanger; the output end of the pipe side of the centralized heat exchanger is connected with the input end of the second three-way pipe fitting, and the input end of the equipment cooling water loop and the condensate connecting pipe at the upstream of the isolating valve VI are connected with the output end of the second three-way pipe fitting.
The secondary circuit waste heat discharging method based on concentrated seawater cooling aims at a waste heat discharging system which comprises a part of steam pipeline and water supply pipeline of the secondary circuit system, a seawater cooling circuit and a concentrated heat exchanger; in the concentrated heat exchanger, the steam from the steam generator in the pipe side exchanges heat with the seawater in the shell side, so that the purpose of cooling the two-loop steam is achieved; during normal operation of the reactor, the centralized heat exchanger is communicated with the equipment cooling water loop through a valve and isolated from the secondary side of the steam generator, and the centralized heat exchanger bears the cooling function of the equipment of the two-loop system; after the reactor is shut down, the system equipment which can normally run only by cooling provided by the centralized heat exchanger in the second loop stops running and is not required to be cooled any more, and the centralized heat exchanger is disconnected with the equipment cooling water loop through a valve. The centralized heat exchanger is constructed through a two-loop steam pipeline, a condensate pipeline and a valve and is connected with the secondary side of the steam generator; steam generated by the secondary side of the steam generator due to heat generation of the reactor core is conveyed to the pipe side of the centralized heat exchanger through a steam pipeline and a steam connecting pipe and cooled in the pipe side of the centralized heat exchanger, and heat is led out to a marine heat trap through a seawater cooling loop by seawater flowing through the shell side, so that the purpose of leading out the waste heat of the reactor core is achieved; the cooled condensate is pressurized by a condensate transfer pump and then is conveyed back to the secondary side of the steam generator through a condensate connecting pipe and a condensate pipeline.
Further preferably, the above-mentioned two-loop active waste heat discharging system of a marine nuclear power plant is adopted to realize the core waste heat discharge, and the method comprises the following steps:
Step 1: after the nuclear power plant is shut down, the shut down signal triggers the isolation valve I, the isolation valve II, the isolation valve III and the isolation valve IV to be closed; the steam generator is disconnected with the steam turbine generator and the condenser; the centralized heat exchanger is disconnected with the equipment cooling water loop; step 2: opening an isolation valve V and an isolation valve VI, putting a condensate transfer pump arranged on a condensate connecting pipe into operation, and constructing a loop channel between a steam generator and a centralized heat exchanger; in the centralized heat exchanger, the steam in the pipe side is condensed by the seawater in the shell side and then is conveyed back to the secondary side of the steam generator by the condensed water pump; after the condensate water transfer pump operates, water in the concentrated heat exchanger is continuously conveyed to the steam generator, so that the establishment of a steam space in the side of the tube of the concentrated heat exchanger is ensured.
Further preferably, the method further comprises the step 3: the dynamic balance between the steam flow entering the pipe side of the concentrated heat exchanger and the condensate flow returning to the steam generator is realized by adjusting the valve opening of the regulating valve arranged on the condensate connecting pipe.
The invention has the following advantages and beneficial effects:
Aiming at the defects of the primary loop active waste heat discharging system in the aspect of safety and reliability (namely, a pipeline of the primary loop active waste heat discharging system breaks when the primary loop active waste heat discharging system operates so as to trigger radioactive substances to release), the invention combines the technical characteristics of a novel integrated secondary loop system, newly constructs an active waste heat discharging channel based on the secondary side of a steam generator and a concentrated seawater cooling system on the basis of the scheme of the existing concentrated seawater cooling system, fully utilizes equipment integration and shares (namely, directly utilizes the existing concentrated heat exchanger and does not need to newly increase the heat exchanger), and is beneficial to reducing the volume and the weight of the marine nuclear power device; on the other hand, the configuration multiple and diversity of the waste heat discharging system are further expanded, and the purpose of further improving the safety and reliability of the waste heat discharging function of the marine nuclear power device is achieved. Has the following advantages:
1. The invention combines the overall design characteristics of an integrated two-loop system and the centralized seawater cooling system scheme, fully utilizes the characteristic that the residual heat deriving function after the reactor of the marine nuclear power device is shut down and the cooling function of the two-loop equipment in normal operation are not overlapped in time sequence, and realizes the centralized heat exchanger scheme which can take the normal operation working condition single-phase convection heat exchange and the residual heat discharge working condition two-phase condensation heat exchange into consideration. Therefore, no new heat exchanger equipment is needed, the same concentrated heat exchanger is utilized, and the equipment cooling function and the waste heat discharging function are respectively realized under the normal operation and shutdown working conditions of the nuclear power plant, so that the valuable cabin space of the marine nuclear power plant is released, and the weight of the plant is reduced.
2. The waste heat discharging system is a two-loop waste heat discharging system and is not connected with the one-loop system, so that the risk of radioactive substance release when a pipeline of the waste heat discharging system is damaged is avoided.
3. For the marine nuclear power plant provided with the secondary side passive waste heat discharging system, the invention has the following advantages:
1) The branch pipes are not required to be led out again on the main steam pipeline and the water supply pipeline, and the tee pipe fittings are only required to be respectively added on the steam connecting pipe and the condensate connecting pipe of the existing secondary side passive waste heat discharging channel, so that the change of the two-loop system is small, and the influence on the main thermodynamic cycle of the two-loop under the normal operation working condition can be reduced.
2) The secondary side active and passive waste heat discharging channels are in a parallel state, are not opened at the same time, and have no interference with each other.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
FIG. 1 is a schematic diagram of a secondary loop active waste heat removal system for a marine nuclear power plant
In the drawings, the reference numerals and corresponding part names:
1-isolation valve I, 2-isolation valve II, 3-isolation valve III, 4-isolation valve IV, 5-isolation valve V, 6-isolation valve VI, 7-regulating valve, 8-condensed water pump, 9-steam generator, 10-concentrated heat exchanger, 11-condenser, 12-steam turbine, 13-ocean thermal trap, 14-two loop system cooling part sleeves, 15-equipment cooling water loop and 16-sea water cooling loop.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following examples and fig. 1, wherein the exemplary embodiments of the present invention and the descriptions thereof are only for explaining the present invention, and are not limiting the present invention.
Example 1
The embodiment provides a secondary loop active waste heat discharging system of a marine nuclear power plant, which comprises a steam pipeline and a water supply pipeline of a secondary loop system, a steam connecting pipe and a condensate connecting pipe, a centralized heat exchanger 10, an equipment cooling water loop 15 and a seawater cooling loop 16, wherein the steam connecting pipe and the condensate connecting pipe are respectively connected with an inlet and an outlet at the pipe side of the centralized heat exchanger, and an outlet and an inlet of the seawater cooling loop are respectively connected with an inlet and an outlet at the shell side of the centralized heat exchanger; the centralized heat exchanger 10 is used to take over the cooling function of the two-circuit device during normal operation of the nuclear power plant and to take over the waste heat removal function when the nuclear power plant is shut down.
The main equipment of the two-loop system comprises a steam generator 9, a steam turbine 12 and a condenser 11; the steam generator 9 is connected with the steam turbine 12 through a steam pipeline, the steam which becomes exhaust steam after acting in the steam turbine 12 enters the condenser 11 through a final stage blade of a low pressure cylinder of the steam turbine, and the condenser 11 is connected with the steam generator 9 through a water supply pipeline; the seawater cooling circuit 16 further comprises a marine heat trap 13, and an output end and an input end of the marine heat trap 13 are respectively connected with an input end and an output end of the shell side of the centralized heat exchanger 10 through pipelines.
The input end of the steam connecting pipe is connected to the steam pipeline of the two-loop system, the output end of the steam connecting pipe is connected to the input end of the pipe side of the centralized heat exchanger 10, the input end of the condensate connecting pipe is connected to the output end of the pipe side of the centralized heat exchanger 10, and the output end of the condensate connecting pipe is connected to the water supply pipeline of the two-loop system.
The system also comprises an isolation valve I1, an isolation valve II2, an isolation valve III3, an isolation valve IV 4, an isolation valve V5, an isolation valve VI 6, a regulating valve 7, a condensate water transfer pump 8 and a check valve; an isolation valve I1 is provided on the steam line to the turbine 12 downstream of the steam nozzle access point and upstream of the turbine 12; the isolation valve II2 is arranged on the feed line from the condenser 11 to the steam generator 9, upstream of the condensate take-over point, downstream of the condenser 11. Isolation valves III3 and IV 4 are respectively arranged at the input end and the output end of the equipment cooling water loop 15; the isolation valve V5 is arranged on the steam connecting pipe; according to the fluid flow direction, the isolating valve VI 6, the regulating valve 7 and the condensate water transfer pump 8 are arranged on the condensate water connecting pipe in sequence. The condensate connecting pipe is also provided with a check valve, and the check valve is positioned at the downstream of the condensate connecting pipe access point.
As a preferred scheme, the output end of the steam connecting pipe and the equipment cooling water loop 15 at the downstream of the isolation valve V5 is connected with the input end of a first three-way pipe fitting, and the output end of the first three-way pipe fitting is connected with the input end of the pipe side of the concentrated heat exchanger; the output end of the pipe side of the centralized heat exchanger is connected with the input end of the second three-way pipe fitting, and the input end of the equipment cooling water loop 15 and the condensate connecting pipe at the upstream of the isolating valve VI 6 are connected with the output end of the second three-way pipe fitting.
The isolation valves I1, II2, III3, IV 4 and V5 and VI 6 of the invention all adopt electromagnetic isolation valves. Isolation valve I1, isolation valve II2, isolation valve III3, and isolation valve IV 4: and when the reactor is in normal operation, the reactor is kept in an electrified normally-open state, and after the reactor is shut down and the gas turbine is shut down, the valve is automatically closed due to reliable electricity loss. Isolation valve v5 and isolation valve vi 6: and when the reactor is in normal operation, the power supply is kept in a normally closed state, and after the reactor is shut down and the gas turbine is shut down, the valve is automatically opened due to reliable power loss.
The centralized heat exchanger 10 is key equipment for realizing the secondary side active waste heat discharging function. The nuclear power plant operates normally, the centralized heat exchanger 10 bears the cooling function of two-loop equipment, and the working medium to be cooled is single-phase fresh water; and under the working condition of waste heat discharge, the concentrated heat exchanger 10 bears the secondary side steam condensing function of the steam generator, and the medium to be cooled is high-temperature steam. When the concentrated heat exchanger 10 bears the cooling function and the waste heat discharging function of the two-loop equipment, the working temperature difference is obvious, and the heat stress and the thermal deformation of the heat exchanger are easily caused. In order to solve the problems, the heat exchange tube adopted by the heat exchange tube of the centralized heat exchanger needs to have a free expansion margin without rigid constraint at one end, so that the heat stress generated when the thermal deformation of the shell side and the tube side is inconsistent is avoided.
The opening of the regulating valve 7 is automatically regulated according to the steam flow flowing into the centralized heat exchanger, so that the steam flow flowing into the centralized heat exchanger and the condensate flow flowing out of the centralized heat exchanger are ensured to keep dynamic balance, and the aim of maintaining the water level of the centralized heat exchanger to be stable is fulfilled.
Example 2
The embodiment provides a secondary circuit waste heat discharging system and a secondary circuit waste heat discharging method based on concentrated seawater cooling, which are realized by adopting the secondary circuit active waste heat discharging system of the marine nuclear power device provided by the embodiment 1, and the specific realization steps are as follows:
Step 1: after the nuclear power plant is shut down, the shut down signal triggers the following valves to close: isolation valve I1 on the steam line to turbine 12, isolation valve II2 on the feedwater line from condenser 11 to steam generator 9, and isolation valves III3 and iv 4 on plant cooling water circuit 15.
Step 2: the isolating valve V5 on the steam connecting pipe at the inlet of the centralized heat exchanger 10, the isolating valve VI 6 on the condensate connecting pipe and the condensate transfer pump 8 are respectively started and operated after receiving the starting instruction. Because the centralized heat exchanger bears the cooling function of the two-loop system equipment under the normal operation condition of the reactor, the working medium is single-phase fresh water, and the pipe side of the centralized heat exchanger 10 is filled with the single-phase fresh water. After the condensate pump 8 operates, water at the tube side of the concentrated heat exchanger 10 is conveyed to the steam generator 9 at a constant flow rate so as to ensure the establishment of a steam space at the tube side of the concentrated heat exchanger 10.
Step 3: preliminary calculation shows that the actual heat exchange area of the centralized heat exchanger 10 is far higher than the heat exchange area required by steam condensation under the condition of waste heat discharge. In order to prevent the condensation rate of the steam on the tube side of the centralized heat exchanger 10 from being too high, which results in too high cooling rate of the primary loop system, the tube side of the centralized heat exchanger 10 needs to maintain a certain condensate level to reduce the contact area between the steam and the heat exchange tube bundle, i.e. to control the actual heat exchange area not to be too large. However, when the residual heat discharging function is performed, since the core residual heat level is lowered with time, the steam condensing load in the concentrated heat exchanger 10 is also lowered with time, and in order to ensure a dynamic balance between the steam condensing flow rate entering the concentrated heat exchanger 10 and the condensate flow rate returning to the steam generator 9, a regulating valve 7 may be provided on the condensate take-over. The opening of the valve is automatically regulated according to the steam flow flowing into the centralized heat exchanger 10 so as to ensure that the steam flow flowing into the centralized heat exchanger 10 and the condensate flow flowing out of the centralized heat exchanger 10 keep dynamic balance, thereby achieving the purpose of maintaining the stable liquid level of the centralized heat exchanger 10.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. A secondary circuit waste heat discharging system based on concentrated seawater cooling comprises a part of steam pipeline and water supply pipeline of the secondary circuit system, a seawater cooling circuit and a concentrated heat exchanger; when the nuclear power plant is in normal operation, the tube side in the centralized heat exchanger is used for flowing fresh water; when the nuclear power plant is stopped, the tube side in the centralized heat exchanger is used for steam/condensed water; the seawater of the medium at the side of the cooling pipe flows at the shell side in the concentrated heat exchanger, and the concentrated heat exchanger is used for bearing the two-loop steam cooling function after the reactor is shut down,
The system comprises a concentrated heat exchanger tube side, a water supply pipeline, a water collecting pipe and a water collecting pipe, wherein the water supply pipeline is connected with the water supply pipeline;
The system also comprises an isolation valve I, an isolation valve II, an isolation valve III, an isolation valve IV, an isolation valve V, an isolation valve VI and a condensate water transfer pump; the isolation valve I is arranged on a steam pipeline leading to the steam turbine and is positioned downstream of the steam connecting pipe access point; the isolation valve II is arranged on a water supply pipeline leading from the condenser to the steam generator and is positioned at the upstream of the condensate pipe access point; the isolation valve III and the isolation valve IV are respectively arranged at the input end and the output end of the equipment cooling water loop; the isolation valve V is arranged on the steam connecting pipe, and the condensed water transfer pump and the isolation valve VI are both arranged on the condensed water connecting pipe;
The output end of the steam connecting pipe at the downstream of the isolation valve V and the output end of the equipment cooling water loop are connected with the input end of a first three-way pipe fitting, and the output end of the first three-way pipe fitting is connected to the input end of the pipe side of the concentrated heat exchanger; the output end of the pipe side of the centralized heat exchanger is connected with the input end of the second three-way pipe fitting, and the input end of the equipment cooling water loop and the condensate connecting pipe at the upstream of the isolating valve VI are connected with the output end of the second three-way pipe fitting.
2. The two-circuit waste heat discharging system based on concentrated seawater cooling as claimed in claim 1, wherein the condensate pipe is further provided with a regulating valve.
3. The two-circuit residual heat removal system based on concentrated seawater cooling according to claim 1, wherein a check valve is further arranged on the condensate pipe, and the check valve is positioned downstream of the condensate water transfer pump.
4. The two-circuit waste heat removal system based on concentrated seawater cooling as claimed in claim 1, wherein the heat exchange tube of the concentrated heat exchanger is a U-shaped tube heat exchange tube.
5. The two-circuit waste heat removal system based on concentrated seawater cooling as claimed in claim 1, wherein the main equipment of the two-circuit system comprises a steam generator, a steam turbine and a condenser; the steam generator is connected with the steam turbine through a steam pipeline, the steam which becomes dead steam after the work is done in the steam turbine enters the condenser through the last stage blade of the low pressure cylinder of the steam turbine, and the condenser is connected with the steam generator through a water supply pipeline; the isolation valve I is positioned at the upstream of the steam turbine, and the isolation valve II is positioned at the downstream of the condenser.
6. The two-circuit residual heat removal system based on concentrated seawater cooling according to claim 1, wherein the seawater cooling circuit further comprises a marine heat trap, and an output end and an input end of the marine heat trap are respectively connected with an input end and an output end of a shell side of the concentrated heat exchanger through pipelines.
7. The secondary circuit waste heat discharging method based on concentrated seawater cooling is characterized in that the directed waste heat discharging system comprises a part of steam and water feeding pipelines of the secondary circuit, a concentrated heat exchanger and a seawater cooling circuit;
During normal operation of the reactor, the concentrated heat exchanger is communicated with the equipment cooling water loop through a valve and is isolated from the secondary side of the steam generator; the centralized heat exchanger bears the cooling function of the two-loop system equipment,
After the reactor is shut down, the system equipment which can normally run only by the cooling provided by the centralized heat exchanger in the second loop stops running and is not required to be cooled any more, and the centralized heat exchanger and the equipment cooling water loop are disconnected through a valve; the centralized heat exchanger is constructed through a two-loop steam pipeline, a condensate pipeline and a valve and is connected with the secondary side of the steam generator; steam generated by the secondary side of the steam generator due to heat generation of the reactor core is conveyed to the centralized heat exchanger through a steam pipeline and a steam connecting pipe and cooled in the centralized heat exchanger, and the heat is led out to the ocean thermal trap through a seawater cooling loop, so that the purpose of leading out the waste heat of the reactor core is achieved; the cooled condensate is pressurized by a condensate transfer pump and then is conveyed back to the secondary side of the steam generator through a condensate connecting pipe and a condensate pipeline.
8. The secondary circuit waste heat discharging method based on concentrated seawater cooling according to claim 7, wherein the secondary circuit active waste heat discharging system of the marine nuclear power plant according to any one of claims 1 to 6 is adopted, and the method comprises the following steps:
step 1: after the nuclear power plant is shut down, the shut down signal triggers the isolation valve I, the isolation valve II, the isolation valve III and the isolation valve IV to be closed; the steam generator is disconnected with the steam turbine generator and the condenser; the centralized heat exchanger is disconnected with the equipment cooling water loop;
Step 2: opening an isolation valve V and an isolation valve VI, and putting a condensate transfer pump arranged on a condensate connecting pipe into operation so as to achieve the purposes of communicating a steam-water circulation loop between the concentrated heat exchanger and the secondary side of the steam generator and establishing a waste heat discharge channel between the secondary side of the steam generator and the concentrated heat exchanger; and after the condensate water transfer pump runs, continuously conveying condensate water in the concentrated heat exchanger to the secondary side of the steam generator so as to ensure the establishment of a steam space in the tube side of the concentrated heat exchanger.
9. The method for exhausting the secondary waste heat based on concentrated seawater cooling as claimed in claim 8, further comprising the step of 3: the dynamic balance between the steam flow entering the centralized heat exchanger and the condensate flow returning to the steam generator is realized by adjusting the valve opening of the regulating valve arranged on the condensate connecting pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210939097.7A CN115274150B (en) | 2022-08-05 | 2022-08-05 | Two-loop waste heat discharging system and method based on concentrated seawater cooling |
Applications Claiming Priority (1)
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