CN110500567B - Efficient nuclear energy utilization system and method - Google Patents
Efficient nuclear energy utilization system and method Download PDFInfo
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- CN110500567B CN110500567B CN201810469995.4A CN201810469995A CN110500567B CN 110500567 B CN110500567 B CN 110500567B CN 201810469995 A CN201810469995 A CN 201810469995A CN 110500567 B CN110500567 B CN 110500567B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/22—Methods of steam generation characterised by form of heating method using combustion under pressure substantially exceeding atmospheric pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes or flue ways
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/50—Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G1/00—Steam superheating characterised by heating method
- F22G1/02—Steam superheating characterised by heating method with heat supply by hot flue gases from the furnace of the steam boiler
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
- F23L15/04—Arrangements of recuperators
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21D—NUCLEAR POWER PLANT
- G21D5/00—Arrangements of reactor and engine in which reactor-produced heat is converted into mechanical energy
- G21D5/04—Reactor and engine not structurally combined
- G21D5/08—Reactor and engine not structurally combined with engine working medium heated in a heat exchanger by the reactor coolant
- G21D5/12—Liquid working medium vaporised by reactor coolant
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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
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
-
- 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
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- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
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Abstract
The invention discloses a high-efficiency nuclear energy utilization system and a method, which comprises a fossil fuel boiler for coupling, wherein the fossil fuel boiler for coupling replaces a water-cooled wall of a traditional boiler with a steam-cooled wall type superheater; the flue gas recirculation system is used for adjusting the flame and the flue gas temperature of different areas of a boiler furnace, the flue gas of the flue gas recirculation system is taken from a draught fan and is pumped to each area of the furnace by a flue gas recirculation fan, and an adjusting air door is arranged on a pipeline from the recirculation fan to each area of the furnace to adjust the amount of the recirculated flue gas to different areas of the furnace, so that the flue gas temperature of each area in the furnace is controllable, and further the flue gas temperature and the steam temperature of each area in the boiler are controllable. The fossil fuel boiler which is specially designed and adopts the flue gas partition recycling technology solves the self-coupling problem of a steam-water system and a combustion system of the fossil fuel boiler for coupling, and enhances the usability of key equipment in the system design of coupling nuclear energy and conventional energy.
Description
Technical Field
The invention relates to the technical field of energy, in particular to a high-efficiency nuclear energy utilization system.
Background
The modern commercial nuclear power plant is mainly a subcritical unit, a coolant in a primary loop of a reactor of the boiling water reactor nuclear power plant is introduced into a steam turbine, and radiation protection and waste treatment are complex, so that a pressurized water reactor is the mainstream of the modern commercial nuclear power technology. Conventional pressurized water reactors are generally two-circuit systems, wherein steam in the two-circuit system drives a steam turbine to generate electricity. Due to the limitation of the temperature of the heat carrier of the reactor (the average outlet temperature of a pressurized water reactor is generally lower than 330 ℃), only saturated steam or slightly superheated steam (the superheat degree is 20-30 ℃) with lower pressure can be produced, the ideal specific enthalpy drop of the whole machine is very small, the steam humidity is high, and the steam flow is inevitably very large in order to increase the power of a single machine. The parameters of the secondary loop system of the current commercial nuclear power plant are about 6-8 MPa of pressure, about 230-290 ℃ of temperature and about 34% of generating efficiency. The supercritical water cooled reactor (SCWR) reactor core outlet parameter pressure is about 25MPa, the temperature is about 500 ℃, compared with the conventional pressurized water reactor, the supercritical water cooled reactor has one less loop, hot fluid at the core outlet directly enters a steam turbine, the system thermal efficiency is close to 45%, and the system thermal efficiency is far higher than the conventional water cooled reactor by 34%. However, supercritical water-cooled reactors are in a research state all the time, but due to the reasons of greatly improved parameters, lack of heat transfer flow experiments and numerical data, lack of chemical properties and mechanical properties of key materials in the reactors under the supercritical water-cooled reactor condition and the like, the technical difficulty is still great, and optimistic documents believe that the reactor needs to have commercial reactor construction capacity by 2028 years.
Most of nuclear power plants use saturated steam, the work of the nuclear turbine 2/3 is completed in a low-pressure cylinder, but the exhaust steam humidity of the low-pressure cylinder of the nuclear turbine is large and generally reaches 12% -14%, and the corrosion and erosion of blades are easily caused, so a half-speed turbine is generally adopted, and a special steam-water separation reheater is required to be added behind the high-pressure cylinder for dehumidification and reheating. And the thermal power plant generally adopts superheated steam, has high superheat degree and generally adopts a full-speed steam turbine. The half-speed turbine rotor has a large diameter and a heavy weight, generally speaking, the material consumption of the half-speed turbine exceeds that of a full-speed turbine by 2 times, and for the whole unit, the weight of the half-speed turbine is about 1.2-2.4 times of that of the full-speed turbine. The bearing load of the corresponding turbine foundation is increased, and the civil engineering investment is increased; the investment of the half-speed turbine in the aspects of transportation, hoisting, installation and the like is higher than that of the full-speed turbine. The cost of equipment and civil engineering is higher by 20-30% than that of full-speed machine (the whole conventional island is about 7% higher).
It is well known that the investment in a nuclear power plant is much greater than that of a thermal power plant, which is generally more thermally efficient than the nuclear power plant. If a proper method is adopted, a proper system is built, and a thermodynamic system of a thermal power plant can be coupled into the nuclear power plant, so that the initial investment can be greatly reduced, the operating thermal efficiency can be greatly improved, and the economy can be greatly improved.
Due to the inherent safety of the high temperature gas cooled reactor, the design of the fuel element can allow the temperature to reach 1600 ℃, so that the 10MW high temperature gas cooled experimental reactor is built. Document zhushitang 'research on supercritical cycle one-time reheating scheme of modular high-temperature gas-cooled reactor', 2007 proposes a scheme of coupling the technology of modular high-temperature gas-cooled reactor with the mature supercritical steam power cycle technology, and adopts a scheme of matching a machine with multiple reactors, wherein a first loop adopts a helium closed cycle, helium flows through a pebble bed reactor core from top to bottom and is heated to about 750 ℃, a second loop adopts water and steam cycles, and steam is heated by helium to the temperature required by the supercritical steam power cycle, such as 565 ℃, and the power generation efficiency of the helium closed cycle reaches more than 45%.
The technical difficulty to be solved by the nuclear island breakthrough is far higher than that of the conventional thermal power equipment, so that the key point of nuclear power and supercritical steam power cycle coupling is that the nuclear island equipment cannot be expected to be breached to adapt to thermal power parameters, but the thermal power equipment is breached to adapt to the nuclear island parameters, but the thought is not always noticed by researchers.
In the prior art, a series-parallel connection coupling power generation system of nuclear energy and conventional energy and a direct overheating coupling power generation system of the nuclear energy and the conventional energy are disclosed, but specific implementation schemes of conventional energy boilers are not provided. Although the boiler coupled with the nuclear power and the conventional energy source adopts the conventional fossil fuel, the boundary conditions of the boiler, particularly the design of the boiler island, are greatly different from the traditional boiler which only burns the fossil fuel. As is known, a boiler is composed of a "boiler" which mainly refers to a steam-water system and belongs to a heat absorption function, and a "furnace" which mainly refers to a combustion system and belongs to a heat release function. The boiler has the self-coupling problem of a steam-water system and a combustion system, and the self-coupling problem can cause various dangerous consequences such as dry burning of the boiler, unstable pressure of a hearth and even overpressure explosion. The technical measures taken to satisfy the coupling of the steam-water system and the combustion system are different for each specific boiler type. The traditional boiler which only burns fossil fuel heats liquid water to saturated steam, and then continuously heats the saturated steam to superheated steam; the 'boiler' of the boiler with nuclear energy coupled with fossil fuel heats the saturated steam or slightly superheated steam coming out from the nuclear island to highly superheated steam, and the special boiler does not have the process of heating liquid water to saturated steam, namely, the process of vaporization, because the latent heat of vaporization is absorbed by water not in the boiler, but in the nuclear island with more suitable conditions in various aspects such as temperature range and the like. The method brings a new problem to the design of a boiler adopted by nuclear power and fossil energy coupling, and a solution of the problem is not reported in a published document.
In summary, in the prior art, an effective solution for the problem of a special boiler in a nuclear energy and conventional energy coupling system is still lacking.
Disclosure of Invention
In order to solve the defects of the prior art, one of the purposes of the invention is to provide an efficient nuclear energy utilization system, which solves the self-coupling problem of a steam-water system and a combustion system of a fossil fuel boiler for coupling, realizes that the fossil fuel boiler for coupling heats saturated steam or slightly superheated steam output from a nuclear island to highly superheated steam, and enhances the usability of key equipment in the system design of coupling nuclear energy with conventional energy.
A high-efficiency nuclear energy utilization system comprises a condensed water system, a water supply system, a steam generation system and a steam work system, wherein the condensed water system sequentially outputs condensed water to a condensed water low-heating regenerator, a flue gas waste heat utilization device, another level of condensed water low-heating regenerator and a deaerator for heating;
the water supply system pumps the water heated by the deaerator into the nuclear island for heating through a water supply pump;
the steam generation system comprises a nuclear island and a coupling fossil fuel boiler, the feed water is heated and evaporated in the nuclear island to form saturated steam or slightly superheated steam with lower temperature, the steam output by the nuclear island is divided into two paths, one path of steam is mainly subjected to convection heat exchange, namely is output to a low-temperature convection superheater of the coupling fossil fuel boiler, the low-temperature convection superheater is arranged in a position close to a hearth outlet in a hearth, and the flue gas heats the saturated steam or slightly superheated steam with lower temperature output from the nuclear island through the low-temperature convection superheater; the other path of steam is output to the wall type superheater for heating through a wall type superheater inlet header, the received radiation heat exchange and convection heat exchange are repeated, a wall type superheater outlet header is arranged at the wall type superheater outlet, the two paths of heated steam are converged at a high-temperature convection superheater inlet and are further heated into highly superheated steam in the high-temperature convection superheater;
the heat source of the high-temperature convection superheater is flue gas obtained by merging flue gas from the after-burning area and recirculated flue gas from the expansion area, and the heat source of the low-temperature convection superheater is flue gas obtained by merging flue gas from the expansion area and recirculated flue gas from the convection area;
the steam work system comprises a coupling steam turbine and a generator, the coupling steam turbine comprises a coupling steam turbine high-pressure cylinder and a coupling steam turbine low-pressure cylinder, highly superheated steam output from the outlet of the high-temperature convection superheater enters the coupling steam turbine high-pressure cylinder to do work and drive the generator to generate power, and exhaust steam of the coupling steam turbine high-pressure cylinder enters the coupling steam turbine low-pressure cylinder to further do work and drive the generator to generate power.
In a further preferred embodiment, the high-pressure cylinder of the coupling turbine and the low-pressure cylinder of the coupling turbine are coaxially arranged or are arranged in a split-shaft manner, the high-pressure cylinder and the low-pressure cylinder of the coupling turbine are respectively connected to the corresponding power generators when the split-shaft manner is arranged, the high-pressure cylinder of the coupling turbine is connected to the low-pressure cylinder of the coupling turbine through a main shaft when the split-shaft manner is arranged coaxially, and the low-pressure cylinder of the coupling turbine is connected to the power generator shared by the high-pressure cylinder and the low-pressure cylinder of the coupling turbine through the main shaft.
According to a further preferred technical scheme, the fossil fuel boiler for coupling is connected with a flue gas recirculation system, the flue gas recirculation system is used for adjusting flame and flue gas temperature of different areas of a hearth of the fossil fuel boiler for coupling through inputting flue gas to different areas of the hearth, so that the flue gas temperature of each position in the hearth is controllable, and further the steam temperature in the boiler is controllable everywhere.
According to a further preferable technical scheme, the fossil fuel boiler for coupling comprises a combustion chamber, a hearth and a tail flue, wherein the hearth is positioned at the upper part of the combustion chamber, the tail flue is connected to the hearth, and a wall type superheater is arranged on a furnace wall of the whole hearth;
the hearth is divided into a continuous combustion area, an expansion area and a convection area from bottom to top, and the convection area is sequentially provided with a high-temperature convection superheater and a low-temperature convection superheater from bottom to top;
the dilatation is regional including conic section, the leading straight section of conic section, the regional flue gas recirculation pipeline connector of dilatation is located the leading straight section of conic section, the leading straight section of conic section is located the below of conic section, the leading straight section of conic section is connected with continuous burning region, the regional flue gas recirculation pipeline connector of dilatation is connected from the regional flue gas recirculation pipeline of dilatation, the dilatation is regional to realize the increase-volume cooling to the flue gas from continuous burning region through the regional recirculated flue gas of dilatation that draws after following the stove behind the draught fan or before the draught fan, and the required flue gas volume of its increase convection heat transfer.
The convection area is positioned above the expansion area, the convection heat exchange effect is greatly enhanced due to the large increase of the smoke volume, the possibility of pipe explosion due to overtemperature of a heating surface is greatly reduced due to the cooling of the smoke, the safety of the boiler is greatly improved, and the smoke in the convection area mainly realizes the steam heating in the high-temperature convection superheater and the low-temperature convection superheater in a convection heat exchange mode.
The middle part of convection current region is provided with the regional flue gas recirculation pipeline connector of convection current promptly on the furnace straight section between high temperature convection current over heater and the low temperature convection current over heater in the convection current region, low temperature convection current over heater has been arranged to the regional area of convection current flue gas recirculation pipeline connector, the regional flue gas recirculation pipeline of convection current connector connection has realized the further increase-volume cooling to the flue gas that comes from the export of high temperature convection current over heater through the regional recirculation flue gas of convection current that draws forth behind the draught fan behind the stove or before the draught fan, so further strengthened the convection current heat transfer effect of low temperature convection current over heater, also further reduced the risk of low temperature convection current over heater overtemperature booster simultaneously.
The continuous combustion area comprises a transition straight-section hearth and a continuous combustion area flue gas recirculation pipeline connecting port, the transition straight-section hearth is connected with the top of a combustion chamber below the transition straight-section hearth and is connected with a front straight section of a conical section above the transition straight-section hearth, further combustion of fuel discharged from the combustion chamber is achieved in the transition straight-section hearth, the continuous combustion area flue gas recirculation pipeline connecting port is connected with the continuous combustion area flue gas recirculation pipeline, further capacity increasing and cooling of flue gas from the combustion chamber are achieved through continuous combustion area recirculation flue gas led out from a draught fan behind the furnace or in front of the draught fan, overtemperature pipe explosion of a wall type superheater can be prevented, and part of liquid ash slag which is brought out from the combustion chamber and cannot be timely discharged is cooled into solid ash slag and is agglomerated and settled back to the combustion chamber area, so that the liquid ash slag is prevented from reaching a higher hearth area to contaminate a heating surface.
The convection area flue gas recirculation pipeline is used for further increasing the capacity and reducing the temperature of the flue gas so as to achieve the purpose of improving the convection heat exchange effect of the low-temperature convection superheater, the heat transfer capacity of the convection heat exchange is determined by a heat transfer formula, and the heat transfer formula comprises the flue gas capacity and the end difference.
Further preferred technical scheme, denitrification facility and air heater have set gradually in the afterbody flue, air heater passes through the dust remover and is connected to the draught fan, the low temperature flue gas of fossil fuel boiler output is drawn forth to flue gas waste heat utilization equipment through the draught fan for the coupling, or flue gas waste heat utilization equipment is located between air heater and the dust remover, and the low temperature flue gas is in heat condensate system's condensate water among the flue gas waste heat utilization equipment, the condensate water that is heated in the flue gas waste heat utilization equipment further through low with, oxygen-eliminating device, feed-water pump conveying to the nuclear island.
Further preferred technical scheme, flue gas recirculation system's flue gas is taken behind the draught fan or before taking from the draught fan, is taken out the flue gas to each region of furnace through recirculation line by flue gas recirculation fan, recirculation line carries the flue gas respectively to setting up respectively at continuous burning region, dilatation region, the regional flue gas recirculation line of dilatation, the regional flue gas recirculation line of convection current, the regional flue gas recirculation line of continuous burning, dilatation region flue gas recirculation line, the regional flue gas recirculation line of convection current, all be provided with the air damper on the regional flue gas recirculation line of dilatation, the regional flue gas recirculation line of convection current, the regional flue gas recirculation line of continuous burning for adjust to the not regional recirculated flue gas volume of furnace.
According to a further preferable technical scheme, the inner wall and the outer wall of the combustion chamber of the fossil fuel boiler for coupling are both provided with heat insulation layers made of heat insulation materials, the inlet end of the combustion chamber is connected with a combustor, the combustor is provided with a powder feeding pipeline inlet, and the combustion chamber is provided with a liquid slag discharging port.
According to a further preferred technical scheme, a cooling pipeline is arranged inside the heat preservation layer and is used for emergency standby, water or other media are not introduced during normal operation, and water or other media are introduced to cool the combustion chamber when the accident needs to be cooled.
The flue gas waste heat utilization device is a surface heat exchanger, the heating medium is flue gas, the heated medium is condensed water, and the medium connected to the reactor is heated medium.
In a further preferred embodiment, the fossil fuel boiler for coupling uses a W-shaped flame combustion chamber or a flame combustion chamber of another shape.
Another object of the present invention is to provide a working method of an efficient nuclear energy utilization system, which includes:
the method comprises the steps that water and steam are graded and subjected to parameter increase in a segmented mode by utilizing a nuclear island and a fossil fuel boiler, namely, condensed water is heated to a 1 st section by a condensate system through a shaft seal heater and a #3 low heater, liquid water heated to the 1 st section is heated to a 2 nd section by a flue gas waste heat utilization device after being combusted by the fossil fuel boiler, liquid water heated to the 2 nd section is heated to a 3 rd section by a #2 low heater, liquid water heated to the 3 rd section is heated to a 4 th section by a deaerator, the liquid water heated to the 4 th section is heated to steam by the steam generation system through the nuclear island to be heated to a 5 th section, and steam heated to the 6 th section by the fossil fuel boiler for coupling after the 5 th section is heated to superheated steam; the coupling fossil fuel boiler discharges the burned slag in a liquid state through a liquid slag discharge port; the heat source of the 6 th section heating is flue gas obtained by converging flue gas from a secondary combustion area and recirculated flue gas from a dilatation area, and the heat source of the low-temperature convection superheater is flue gas obtained by converging flue gas from the dilatation area and recirculated flue gas from a convection area.
Saturated steam or micro superheated steam output by the nuclear island enters the fossil fuel boiler for coupling, and the specific steam-water flow is as follows:
the steam output by the nuclear island is divided into two paths, one path of steam is mainly subjected to convection heat exchange, namely is output to the low-temperature convection superheater, and the flue gas heats the saturated steam or the slightly superheated steam with lower temperature output from the nuclear island through the low-temperature convection superheater; the other path of steam is output to a wall type superheater, the received radiation heat exchange and convection heat exchange are repeated, the two paths of heated steam are converged at the inlet of the high-temperature convection superheater and further heated in the high-temperature convection superheater to form highly superheated steam, and then the highly superheated steam enters a coupling steam turbine to do work and generate power;
in order to better control the steam temperature of each heating surface of the fossil fuel boiler for coupling, a flue gas recirculation measure is adopted to adjust the flue gas temperature and the flue gas capacity of each position of a hearth of the fossil fuel boiler for coupling, according to the sequence of physical heights from low to high, a recirculation pipeline at the bottommost layer is positioned in a continuous combustion area, namely, behind an outlet of a combustion chamber, wall type superheaters are arranged on the four walls of the hearth to absorb heat, the flue gas temperature is high, the main radiation heating area is provided with the flue gas recirculation pipeline, and the area is called as a continuous combustion area flue gas recirculation pipeline;
the second layer of the recycling pipeline is a capacity expansion area flue gas recycling pipeline, the capacity expansion area flue gas recycling pipeline is positioned in the capacity expansion area, namely in front of an inlet of the high-temperature convection superheater, low-temperature flue gas cooling and capacity expansion are introduced into the capacity expansion area flue gas recycling pipeline, and a furnace above the capacity expansion area flue gas recycling pipeline is provided with a conical section;
the third layer of recirculation pipeline is positioned between the high-temperature convection superheater and the low-temperature convection superheater, is a convection area flue gas recirculation pipeline and is used for further increasing the capacity and reducing the temperature of the flue gas.
The working medium heated here is water or steam.
Compared with the prior art, the invention has the beneficial effects that:
1. the fossil fuel boiler which is specially designed and adopts the flue gas partition recycling technology solves the self-coupling problem of a steam-water system and a combustion system of the fossil fuel boiler for coupling, and enhances the usability of key equipment in the system design of coupling nuclear energy and conventional energy.
2. The flue gas is recycled in a partitioning mode, so that the low-temperature waste flue gas is utilized, the flue gas capacity is increased, the convection heat exchange effect is improved, and the coal burning quantity is reduced.
3. The design of the expansion conical section fully utilizes the space of the hearth, and saves the weight and the cost of the heating surface of the boiler and a steel structure.
4. The strategy of controlling the flue gas temperature in a subarea mode reduces the risk of overtemperature tube explosion of the heating surface and also reduces the material cost of each heating surface section, particularly the material cost of a low-temperature superheater, and expensive high-temperature-resistant materials do not need to be adopted in the area of the low-temperature superheater.
5. The coupling boiler adopts liquid slag discharge, has stronger adaptability to coal types, reduces contamination on a heating surface, is safer, and is more suitable for being coupled with a nuclear island with higher requirement on safety performance.
6. The advantages of the split-shaft arrangement of the steam turbine further include: the high-pressure cylinder can be arranged at a high position and is arranged nearby a steam outlet of the boiler, so that the length of expensive main steam and steam pipelines is reduced, the manufacturing cost is reduced, and the low-pressure cylinder can be arranged at a low position, so that the civil engineering cost is reduced.
7. The tail flue gas between the exhaust gas after the recycling of the induced draft fan or the air preheater and the dust remover is fully utilized to heat the condensed water, at least one stage of low heating is reduced, the investment of a regenerative system is reduced, and more electricity can be generated by the saved low heating steam extraction.
8. The outlet temperature of the boiler is 500-700 ℃, the efficiency of the steam turbine is greatly improved, and the reliability of the adopted high-temperature resistant material of the heating surface is verified in a recently-put-into-service thermal power plant, so that the system is safe, efficient, energy-saving and environment-friendly.
9. The thermal efficiency of the coupled thermodynamic system is improved to about 45 percent on the basis of 34 percent of the conventional nuclear power, and meanwhile, the adopted nuclear island technology is mature, so that various technical problems (such as a thermal hydraulic calculation problem, a key material performance problem, a radiation protection problem and the like) in the research and application process of a supercritical water-cooled reactor are avoided;
10. along with the improvement of the efficiency, compared with a nuclear power unit with the same generating capacity, the steam quantity required by the coupling unit for generating electricity is greatly reduced by about 15%, and the operation cost of water supplementing treatment is greatly reduced by considering the same steam-water loss.
11. The coupling method makes full use of the technical characteristics of the nuclear island and the fossil fuel boiler, carries out grading and sectional parameter increasing on water and steam, and improves the power generation efficiency by breaking through the idea that thermal power equipment is adapted to the nuclear island parameters. The nuclear island part with higher technical difficulty can be realized by slightly changing the existing mature technology, and the fossil fuel boiler part is easy to realize through the design optimization described in the patent, so that the whole technology is easier to implement compared with other high-efficiency nuclear power technologies (such as a scheme for coupling a modularized high-temperature gas cooled reactor technology with the existing mature supercritical steam power circulation technology, a supercritical water cooled reactor technology and the like proposed in Zhu book Tang 2007).
12. The radiation protection and waste treatment are mature and simple by adopting the conventional nuclear island two-loop technology.
13. A high-pressure heating and heat recovery system is cancelled, the steam extraction amount of a high-pressure cylinder originally used for high-pressure heating and heat recovery can be used for power generation, and high-quality energy is fully utilized; meanwhile, the heat dissipation loss of the heater is cancelled, so that the loss in the energy conversion process is reduced, and the integral energy utilization efficiency of the coupling unit is improved.
14. Because the degree of superheat of steam is high, after the steam turbine applies work, the exhaust steam humidity is far lower than that of a modern commercial nuclear steam turbine, so that the condition of adopting a lighter and more compact full-speed steam turbine is achieved, and the investment is greatly reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a schematic diagram showing the overall structure of an embodiment of the present invention;
FIG. 2 is a schematic diagram of the overall structure of another embodiment of the present invention;
FIG. 3 is a steam flow diagram of the present invention;
in the figure, 1, a nuclear island, 2, a wall superheater outlet header, 3, a low-temperature convection superheater, 4, a high-temperature convection superheater, 5, a combustor, 6, a combustion chamber, 7, a liquid slag discharge port, 8, a heat insulation layer, 9, a continuous combustion zone flue gas recirculation pipeline, 10, an expansion zone flue gas recirculation pipeline, 11, a convection zone flue gas recirculation pipeline, 12, a denitration device, 13, an air preheater, 14, a dust remover, 15, a draught fan, 16, a recirculation fan, 17, a coupling turbine low-pressure cylinder, 18, a deaerator, 19, a water supply pump, 20, #2 low-pressure cylinder, 21, a flue gas waste heat utilization device, 22, #3 low-pressure cylinder, 23, a condenser, 24, a heater, 25, a desulfurization device, 26, a chimney, 27, a coupling turbine high-pressure cylinder, 28, a coupling fossil fuel boiler, 29, a generator, 30, a wall superheater, 31, a high-temperature convection superheater, a denitration device, a liquid slag discharge port, 8, a heat insulation layer, a coupling turbine high-pressure cylinder, a coupling fossil fuel boiler, a generator, a coupling fossil fuel boiler, a heat recovery heat, Wall superheater inlet header.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As described in the background art, the prior art has the defect that no special boiler is available in the coupling system of nuclear energy and conventional energy sources, and in order to solve the technical problems, the application provides a high-efficiency nuclear energy utilization system and method.
In an exemplary embodiment of the present application, as shown in fig. 1, a high-efficiency nuclear energy utilization system is provided, wherein main devices of the system for coupling nuclear energy with a conventional energy source include a nuclear reactor and its auxiliary facilities (referred to as "nuclear island 1" for short), a fossil fuel boiler 28 for coupling, a high-pressure turbine cylinder 27 for coupling, a low-pressure turbine cylinder 17 for coupling, a generator 29, #2 low-pressure heater 20 (low-heating regenerator), #3 low-pressure heater 22 (low-heating regenerator), a deaerator 18, a flue gas waste heat utilization device 21, a feed water pump 19, a condenser 23, and other devices. The fossil fuel boiler for coupling adopts flue gas partition recirculation to adjust flame and flue gas temperature in a hearth so as to adjust steam temperature. The modular high temperature gas cooled reactor technology proposed in the prior art is coupled with the supercritical steam power cycle technology which is mature at present, and no fossil fuel boiler is provided in the scheme. In addition, the prior art coupling system of nuclear energy and conventional energy sources does not introduce a coupling measure for coupling the fuel system of the fossil fuel boiler and a steam-water system, but only replaces the system with a heat exchanger schematically.
The heat released in connection with the nuclear island section is primarily used to vaporize water, while the heat released by the coupled thermal power system is primarily used to heat liquid water and increase the degree of supersaturation of steam. The steam pressure entering the steam turbine adopts the inlet pressure of a prokaryotic electric steam turbine, and the steam temperature entering the steam turbine adopts the inlet temperature of a conventional thermal power system (such as subcritical 538 ℃, supercritical 566-700 ℃ and the like). The superheated steam firstly enters a high-pressure cylinder to do work for power generation, the exhaust steam of the high-pressure cylinder after doing work enters a low-pressure cylinder to further do work for power generation, and the exhaust steam after doing work in the low-pressure cylinder enters a condenser to be condensed into condensed water. The condensate system is additionally provided with a flue gas waste heat utilization device at the tail part of a fossil fuel boiler for coupling to heat condensate on the basis of a condensate low-heating and heat-returning system of a conventional thermal power system, and feed water behind a deaerator is pumped into a nuclear island by a feed water pump. The water supply system cancels a high-heating back-heating system, the saved high-heating extracted steam is used for generating more power for the high-pressure cylinder, the traditional mode depends on the water supply heated by the high-heating back-heating, and when the water supply is still kept in a liquid state, the heating is mainly completed in a tail flue gas waste heat utilization device of the fossil fuel boiler.
The coupling and decoupling method relates to a water and water vapor grading sectional rising parameter method. In a traditional thermal power plant, parameter increasing processes of water and steam are carried out in a fossil fuel boiler; in a traditional nuclear power plant, the parameter-raising process of water and steam is carried out in a nuclear island. The coupling method described in this patent makes full use of the technical characteristics of the nuclear island and the fossil fuel boiler to perform grading and sectional parameter raising on water and steam, i.e. the shaft seal heater 24 and the #3 low heater 22 (the heat source is from the 3-stage steam extraction of the low pressure cylinder of the steam turbine) heat the 1 st section, the flue gas waste heat utilization device 21 after the combustion of the fossil fuel boiler heats the 2 nd section, the #2 low heater 20 (the heat source is from the 2 nd section of the low pressure cylinder) heats the 3 rd section, the deaerator 18 (the heat source is from the exhaust of the medium pressure cylinder) heats the 4 th section, the nuclear island 1 heats the 5 th section, and the fossil fuel boiler heats the 6 th section. When the steam heating device is in normal operation, the steam heated from the 1 st section to the 6 th section is called as main steam, wherein the heating of the 1 st section, the heating of the 2 nd section and the heating of the 3 rd section are provided with bypasses, and the processes of heating water of the 1 st section, the heating water of the 2 nd section and the heating water of the 3 rd section can be respectively cut off under the working condition of local accidents and directly enter the heating process of the next stage through the bypasses. The nuclear island is a main heating source, and the fossil combustion boiler is a secondary heating source. The heat source for heating in the 5 th stage is from a main heating source, and the heat sources for heating in the 2 nd and 6 th stages are from a secondary heating source. In the secondary heating source, the heating of the 2 nd section of liquid water is a basic heating section, and the heating of the 6 th section of steam is an effect-promoting heating section.
Specifically, the heating of the liquid water comes from two aspects, namely a medium-temperature and low-temperature flue gas waste heat utilization device of a fossil fuel boiler and low-heating heat recovery of steam extraction of a steam turbine (in a conventional nuclear power conventional island and a conventional thermal power thermodynamic system, low-heating heat recovery is a conventional technology). The process of water gasification takes place in the steam generator of the nuclear island and the superheating of the water steam takes place in the fossil fuel boiler. The parameters of the water gasification process fully utilize the parameter range of a primary loop of the existing reactor core, for example, the hot end temperature of the primary loop of the AP1000 is about 324 ℃, the upper limit of the outlet temperature of the corresponding secondary loop is basically below 300 ℃ in consideration of factors such as the heat exchange end difference, and the corresponding pressure of the saturated steam at 300 ℃ is about 8.58MPa according to the thermophysical data of the saturated steam. For the preferred two-circuit outlet temperature design parameter of 280 ℃, the saturated steam corresponds to a pressure of about 6.4MPa, which is compatible with the two-circuit pressure and temperature comparisons of modern commercial nuclear power plants. As the parameters of the inlet working medium and the outlet working medium of the nuclear island in the coupling system are very close to the parameters of the inlet working medium and the outlet working medium of the modern commercial nuclear island, the technical difficulty does not exist for the nuclear island, and the technical application difficulty is greatly reduced. In the fossil fuel boiler, the technology has no restrictive factors such as development of key materials, and the like, and can realize the purpose of sectional parameter rise of water and steam by reasonably arranging radiation and convection heating surfaces.
In the coupling thermodynamic system, the steam temperature of the superheated steam entering the steam turbine reaches the parameters close to the power cycle of critical or supercritical steam, generally speaking, the cycle efficiency can be improved by 1 percentage point when the temperature of the new steam at the inlet of the steam turbine is improved by 20 degrees, and by taking the supercritical 566 ℃ as an example, compared with the conventional nuclear island at 280 ℃, the steam temperature is improved by 286 ℃, so the steam cycle efficiency can be improved by about 14.3% theoretically, and the electricity consumption cost can be greatly reduced, meanwhile, due to the improvement of the efficiency, compared with a nuclear power unit with the same generated energy, the steam quantity required by the power generation of the coupling unit can be greatly reduced by more than about 15%, and the water supplementing treatment cost can be greatly reduced by considering the same steam-water loss. On the other hand, because the degree of superheat of steam is high, after the steam turbine applies work, the exhaust steam humidity is far lower than that of a modern commercial nuclear steam turbine, so that the condition of adopting a lighter and more compact full-speed steam turbine is achieved, and the investment is greatly reduced.
To the self-coupling that realizes boiler self fuel system and steam-water system, this application has made fossil fuel boiler for coupling, and the concrete measure lies in: the water-cooled wall of traditional boiler has been cancelled, has increased wall superheater 30, has increased the flue gas recirculation system who is used for adjusting different regional flames of furnace and gas temperature, flue gas recirculation system's flue gas is taken behind the draught fan or is taken before draught fan 15, takes out to each region of furnace by dedicated gas recirculation fan 16, is equipped with the damper on the pipeline in recirculation fan to each region of furnace, can adjust the recirculated flue gas volume of going to different regions to make everywhere gas temperature controllable in the furnace, and then make steam temperature in the "pot" of boiler everywhere all controllable.
Compared with the traditional fossil fuel boiler, the coupling fossil fuel boiler replaces the water-cooled wall of the traditional boiler with a steam-cooled wall superheater; because the water-cooled wall is not available, the advantage that the water in the boiler is convenient to control the temperature in the boiler in the phase change process can not be exerted, and the combustion chamber with the heat insulation design is adopted. The factors such as strong washing of the burnt fly ash on the heating surface, contamination of the fly ash on the heating surface and the like can possibly cause accidents such as maintenance and shutdown of the boiler, and for a nuclear energy coupled fossil energy boiler system, the unplanned shutdown of the boiler can also cause shutdown of a nuclear island coupled with the boiler and corresponding safety problems of a nuclear reactor.
Compared with the solid slag discharge, the combustion temperature of a hearth required by the liquid slag discharge is higher for coal with the same quality, and the combustion chamber adopting the heat insulation design is more favorable for the liquid slag discharge because the heat is not absorbed in the combustion chamber. Because contamination is reduced, the adaptability of the liquid-state slagging boiler to coal types is stronger, the boiler is safer, and the liquid-state slagging boiler is more suitable for being coupled with a nuclear island with higher requirements on safety performance.
The traditional fossil energy boiler needs a process of phase change of water from liquid to gas, so the proportion of a radiation heating surface in the heating surface is higher, the process of phase change of water from liquid to gas does not exist in a heat absorption system of the coupled fossil fuel boiler, and the process of converting steam from saturated steam or micro superheated steam into highly superheated steam mainly adopts convection heat exchange rather than radiation heat exchange, so more convection heat exchange surfaces rather than radiation heat exchange surfaces are arranged in a hearth.
For the convection heat exchange surface, the flow velocity of the flue gas is very important for the heat exchange effect. The flow velocity is high, the convective heat transfer coefficient is high, the heat transfer effect is good, and the thermal efficiency of the boiler is generally high. The temperature of the steam at the outlet of the boiler required by the invention is 700 ℃ or below, so that the reasonable smoke is a large amount of middle-temperature smoke at about 1000 ℃ rather than a small amount of high-temperature smoke at about 2000 ℃.
However, the ash melting point is generally about 1500 ℃, in order to achieve slag tapping, the temperature of the combustion chamber with the heat insulation design can be as high as 2000 ℃, but the flue gas after combustion enters a heat exchange area, and if the temperature of the flue gas participating in heat exchange is still as high as 2000 ℃, the cost of the adopted high-temperature resistant material is also greatly higher than that of the scheme that the flue gas participates in heat exchange at 1000 ℃.
Therefore, in order to reduce the investment of the heating surface of the boiler and improve the heat exchange efficiency, a feasible method is to extract low-temperature flue gas from the rear of the boiler to enter a hearth for recirculation, so that the flue gas temperature of a heat exchange area is reduced, the flue gas amount is increased, and the convection heat exchange effect is improved. Preferably, low-temperature flue gas with the temperature of 200 ℃ or below after the induced draft fan can be adopted.
Preferably, the boiler adopts W type flame combustion chamber, adopts insulation material thermal insulation around the combustion chamber, and the inside cooling tube way that sets up a small amount of heat preservation is as emergent reserve, and normal operating does not lead to water, lets in water and cools off the combustion chamber when the accident needs the cooling.
The flow sequence of the saturated steam or the micro superheated steam from the nuclear island entering the fossil fuel boiler for coupling is shown in fig. 3:
that is, the steam from the nuclear island is divided into two paths, one path is mainly convection heat exchange, namely, a low-temperature convection superheater, and is arranged in the position, close to the outlet of the hearth, in the hearth, a plurality of heated surfaces are arranged from the combustion chamber to the outlet of the hearth, and a specially-arranged convection region recirculating flue gas pipeline is arranged to further increase the volume (increase the volume flow) of the flue gas and reduce the temperature of the flue gas, so that the temperature of the flue gas is lower, and the steam is suitable for heating saturated steam or slightly superheated steam with the temperature not particularly high (below about 300 ℃); the other path is output to a wall type superheater, the received radiation heat exchange and convection heat exchange are repeated, the wall type superheater is arranged on the furnace wall of the whole hearth (except a combustion chamber), the wall type superheater is similar to a water cooling wall of a traditional boiler (the traditional boiler also has the expression and arrangement of the wall type superheater, but the proportion occupied in the heating surface of the four walls of the hearth is very small and can only be added by the water cooling wall), a wall type superheater inlet header 31 is arranged at the inlet of the wall type superheater 30, and a wall type superheater outlet header 2 is arranged at the outlet of the wall type superheater 30. The two paths are merged at the inlet of the high-temperature convection superheater 4, and are further heated in the high-temperature convection superheater to form highly superheated steam, and then the highly superheated steam enters a high-pressure cylinder of a steam turbine for coupling to do work and generate power. The exhaust steam of the high-pressure cylinder of the coupling steam turbine enters the low-pressure cylinder of the coupling steam turbine to further do work and generate power.
In order to match the arrangement of a steam-water system, a flue gas recirculation measure is adopted to adjust the flue gas temperature and the flue gas capacity of each part of the hearth. According to the sequence of physical height from low to high, the lowest layer of the recirculation pipeline is positioned in a reburning area, namely a combustion chamber outlet, the four walls of the furnace chamber are provided with wall type superheaters for absorbing heat, the temperature of flue gas is high and is a main radiation heating area, but in order to prevent pipe explosion caused by overheating of the heating surface and to cool part of liquid ash slag which is brought out from the combustion chamber and cannot be discharged in time into a solid state and agglomerate and settle back to the combustion chamber area, and the liquid ash slag is prevented from reaching a higher furnace chamber area to contaminate the heating surface, the area is specially provided with the flue gas recirculation pipeline which is called as a reburning area flue gas recirculation pipeline 9.
The second layer of recirculation pipeline is a flue gas recirculation pipeline 10 in the expansion area, namely an inlet of the high-temperature convection superheater, and the convection heat exchanger needs a large amount of flue gas (the flow rate can be increased to further enhance the heat exchange effect) and the temperature is about 1500 ℃ below zero, so that the low-temperature flue gas cooling and capacity increasing is introduced, namely the flue gas recirculation pipeline in the expansion area.
The third layer of recirculation pipeline is located between the high-temperature convection superheater 4 and the low-temperature convection superheater 3, is a convection area flue gas recirculation pipeline 11 and is used for further increasing the capacity and reducing the temperature of flue gas, the lower flue gas temperature can reduce the risk of overtemperature pipe explosion of a heating surface, the material cost of the low-temperature superheater is also reduced, and the larger flue gas amount can improve the heating effect of the low-temperature superheater. Meanwhile, the reduced flue gas temperature can ensure that the denitration device adopts a common catalyst instead of an expensive high-temperature catalyst, thereby reducing the investment and running replacement cost.
The bottom of fossil fuel boiler is combustion chamber 6, and the both ends of combustion chamber are provided with combustor 5 respectively, and the bottom of combustion chamber is provided with liquid row cinder notch 7, and the inner wall and the outer wall of combustion chamber are provided with heat preservation 8 respectively.
As shown in fig. 1, flue gas output by the fossil fuel boiler sequentially passes through a denitration device 12, an air preheater 13, a dust remover 14 and an induced draft fan 15, and then is divided into two paths, wherein one path is connected to a flue gas waste heat utilization device, and the other path is connected to a recirculation fan. The output end of the flue gas waste heat utilization device is sequentially connected to the desulphurization device 25 and the chimney 26. Wherein, the flue gas of the flue gas recirculation system is taken from behind the induced draft fan or taken from in front of the induced draft fan.
In another embodiment of the present invention, as shown in fig. 2, the flue gas waste heat utilization device 21 is disposed between the air preheater 13 and the dust remover 14, and the condensed water is connected to the #2 low heater through the flue gas waste heat utilization device 21 via the #3 low heater.
The high pressure cylinder and the low pressure cylinder of the steam turbine in the application can be arranged coaxially or in a split mode. When the split shaft is arranged, one more generator is needed.
The application cancels a high-pressure heating and back-heating system, and reduces high-pressure heating extraction steam, so the reduced extraction steam can be used for more power generation, and the power of a condensing steam turbine can be increased by 10% and the power of a heating steam turbine can be increased by 14% when the high-pressure heating (high-pressure heater) of the traditional thermal power plant is completely withdrawn from the back-heating system.
For the traditional thermal power plant, high heat extraction can cause reduction of cycle thermal efficiency, so that the power generation can be performed more, but the coal consumption is increased, so that the synthesis is not economical; however, for a nuclear energy and fossil energy coupling system with the 1000MW grade, as the requirement of the water inlet temperature of a nuclear island is not higher than 220 ℃, the water inlet temperature is lower than the water supply temperature of 300 ℃ of a traditional 1000MW thermal power plant, and the temperature of a deaerator is about 220 ℃, the circulating heat efficiency can not be reduced even if high heating is not set.
The high-pressure heater of traditional mode is located the feed pump export, and the pressure that bears is high, and works under higher temperature, and operating condition is poor, and the chance that breaks down is more. Once a fault occurs or when the shell side is full of water due to serious leakage, steam and water are possibly led into a steam turbine to endanger the safety of a unit, so that the high-heating-rate heat recovery system is cancelled, the circulating heat efficiency is not reduced, the power generation amount is improved, and the safety of the system is also enhanced.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A high-efficiency nuclear energy utilization system is characterized by comprising a condensed water system, a water supply system, a steam generation system and a steam work system, wherein the condensed water system sequentially outputs condensed water to a condensed water low-heating regenerator, a flue gas waste heat utilization device, another level of condensed water low-heating regenerator and a deaerator for heating;
the water supply system pumps the water heated by the deaerator into the nuclear island for heating through a water supply pump;
the steam generation system comprises a nuclear island and a coupling fossil fuel boiler, the feed water is heated and evaporated in the nuclear island to form saturated steam or slightly superheated steam with lower temperature, the steam output by the nuclear island is divided into two paths, one path of steam is mainly subjected to convection heat exchange, namely is output to a low-temperature convection superheater of the coupling fossil fuel boiler, the low-temperature convection superheater is arranged in a position close to a hearth outlet in a hearth, and the flue gas heats the saturated steam or slightly superheated steam with lower temperature output from the nuclear island through the low-temperature convection superheater; the other path of steam is output to the wall type superheater for heating through a wall type superheater inlet header, the received radiation heat exchange and convection heat exchange are repeated, a wall type superheater outlet header is arranged at the wall type superheater outlet, the two paths of heated steam are converged at a high-temperature convection superheater inlet and are further heated into highly superheated steam in the high-temperature convection superheater;
the steam work system comprises a coupling steam turbine and a generator, the coupling steam turbine comprises a coupling steam turbine high-pressure cylinder and a coupling steam turbine low-pressure cylinder, the highly superheated steam output from the outlet of the high-temperature convection superheater enters the coupling steam turbine high-pressure cylinder to do work and drive the generator to generate electricity, and the exhaust steam of the coupling steam turbine high-pressure cylinder enters the coupling steam turbine low-pressure cylinder to further do work and drive the generator to generate electricity;
the hearth is divided into a continuous combustion area, an expansion area and a convection area from bottom to top, wherein the continuous combustion area comprises a section of transition straight-section hearth and a continuous combustion area flue gas recirculation pipeline connecting port; the expansion area comprises a conical section, a front straight section of the conical section and a flue gas recirculation pipeline connecting port of the expansion area, and the flue gas recirculation pipeline connecting port of the expansion area is positioned on the front straight section of the conical section; a convection area flue gas recirculation pipeline connecting port is arranged in the middle of the convection area, namely on a straight section of a hearth between the high-temperature convection superheater and the low-temperature convection superheater; the fossil fuel boiler for coupling is connected with a flue gas recirculation system, and a capacity expansion area flue gas recirculation pipeline connecting port is connected with a self-capacity expansion area flue gas recirculation pipeline; the convection area flue gas recirculation pipeline is connected with the convection area flue gas recirculation pipeline through a connecting port; the connection port of the flue gas recirculation pipeline of the continuous combustion area is connected with the flue gas recirculation pipeline of the continuous combustion area; the flue gas recirculation system is used for adjusting flame and flue gas temperature of different areas of the hearth by inputting flue gas to different areas of the hearth of the coupling fossil fuel boiler, so that the flue gas temperature of each position in the hearth is controllable, and further the steam temperature in the boiler is controllable everywhere.
2. The system of claim 1, wherein the high-efficiency nuclear energy utilization system comprises a high-pressure cylinder of the coupling turbine and a low-pressure cylinder of the coupling turbine, which are coaxially or separately arranged, wherein the high-pressure cylinder and the low-pressure cylinder of the coupling turbine are respectively connected to the corresponding power generators when the coupling turbine and the low-pressure cylinder are coaxially arranged, the high-pressure cylinder of the coupling turbine is connected to the low-pressure cylinder of the coupling turbine through a main shaft when the coupling turbine and the low-pressure cylinder of the coupling turbine are connected to the power generator shared by the high-pressure cylinder and the low-pressure cylinder of the coupling turbine through the main shaft when the coupling turbine and the low-pressure cylinder are coaxially arranged.
3. The system of claim 1, wherein the fossil-fuel-fired coupling boiler comprises a combustion chamber, a furnace located at an upper portion of the combustion chamber, and a back flue connected to the furnace, the wall superheater being disposed on a wall of the entire furnace;
the convection area is provided with a high-temperature convection superheater and a low-temperature convection superheater from bottom to top in sequence.
4. The efficient nuclear energy utilization system of claim 3, wherein the straight forward section of the conical section is located below the conical section, and the straight forward section of the conical section is connected to the after-burning zone;
in the convection area, a low-temperature convection superheater is arranged in an area above a connection port of the convection flue gas recirculation pipeline;
the continuous combustion area comprises a transition straight-section hearth, the transition straight-section hearth is connected with the top of the combustion chamber below the transition straight-section hearth and is connected with the front straight section of the conical section above the transition straight-section hearth, and further combustion of fuel discharged from the combustion chamber is realized in the transition straight-section hearth.
5. The system of claim 3, wherein a denitration device and an air preheater are sequentially disposed in the tail flue, the air preheater is connected to an induced draft fan through a dust remover, the low-temperature flue gas output by the fossil fuel boiler for coupling is led out to the flue gas waste heat utilization device through the induced draft fan, or the flue gas waste heat utilization device is located between the air preheater and the dust remover, and the low-temperature flue gas heats the condensed water of the condensed water system in the flue gas waste heat utilization device.
6. The system of claim 3, wherein the flue gas of the flue gas recirculation system is taken from behind the induced draft fan or from in front of the induced draft fan, the recirculation pipeline conveys the flue gas to the expansion area flue gas recirculation pipeline, the convection area flue gas recirculation pipeline and the continuous combustion area flue gas recirculation pipeline which are respectively arranged in the continuous combustion area, the expansion area and the convection area through the flue gas recirculation fan, and the expansion area flue gas recirculation pipeline, the convection area flue gas recirculation pipeline and the continuous combustion area flue gas recirculation pipeline are respectively provided with a damper for adjusting the amount of the recirculated flue gas to different areas of the furnace.
7. The system of claim 1, wherein the inner wall and the outer wall of the combustion chamber of the fossil fuel boiler for coupling are provided with heat insulation layers made of heat insulation materials, the inlet end of the combustion chamber is connected with a burner, the burner is provided with a powder feeding pipeline inlet, and the combustion chamber is provided with a liquid slag discharge port.
8. The system as claimed in claim 7, wherein a cooling pipeline is arranged in the insulating layer for emergency standby, no water or other medium is introduced during normal operation, and water or other medium is introduced to cool the combustion chamber when the temperature of the accident needs to be reduced.
9. A high efficiency nuclear power utilizing system as claimed in claim 1 wherein said coupling fossil fuel fired boiler employs a W-flame combustor.
10. The method of claim 1, further comprising:
the method comprises the steps that water and steam are graded and subjected to sectional parameter rise by a nuclear island and a fossil fuel boiler, namely, condensed water is heated by a condensed water system through a shaft seal heater and a condensed water low-heating regenerator to be heated in a 1 st section, liquid water after the heating in the 1 st section is heated by a flue gas waste heat utilization device after the combustion of the fossil fuel boiler to be heated in a 2 nd section, liquid water after the heating in the 2 nd section is heated by another stage of condensed water low-heating regenerator to be heated in a 3 rd section, liquid water after the heating in the 3 rd section is heated by a deaerator to be heated in a 4 th section, the liquid water after the heating in the 4 th section is heated by the steam generating system to be steam to be heated in a 5 th section through the nuclear island, and the steam after the heating in the 5 th section is heated by the fossil fuel boiler for coupling to be superheated steam to be heated in a 6 th section; the coupling fossil fuel boiler discharges the burned slag in a liquid state through a liquid slag discharge port;
saturated steam or micro superheated steam output by the nuclear island enters the fossil fuel boiler for coupling, and the specific steam-water flow is as follows: the steam output by the nuclear island is divided into two paths, one path of steam is mainly subjected to convection heat exchange, namely is output to the low-temperature convection superheater, and the flue gas heats the saturated steam or the slightly superheated steam with lower temperature output from the nuclear island through the low-temperature convection superheater; the other path of steam is output to a wall type superheater, the received radiation heat exchange and convection heat exchange are repeated, the two paths of heated steam are converged at the inlet of the high-temperature convection superheater and further heated in the high-temperature convection superheater to form highly superheated steam, and then the highly superheated steam enters a coupling steam turbine to do work and generate power;
in order to better control the steam temperature of each heating surface of the fossil fuel boiler for coupling, a flue gas recirculation measure is adopted to adjust the flue gas temperature and the flue gas capacity of each position of a hearth of the fossil fuel boiler for coupling, according to the sequence of physical heights from low to high, a recirculation pipeline at the bottommost layer is positioned in a continuous combustion area, namely, behind an outlet of a combustion chamber, wall type superheaters are arranged on the four walls of the hearth to absorb heat, the flue gas temperature is high, the main radiation heating area is provided with the flue gas recirculation pipeline, and the area is called as a continuous combustion area flue gas recirculation pipeline;
the second layer of the recycling pipeline is a capacity expansion area flue gas recycling pipeline, the capacity expansion area flue gas recycling pipeline is positioned in the capacity expansion area, namely in front of an inlet of the high-temperature convection superheater, low-temperature flue gas cooling and capacity expansion are introduced into the capacity expansion area flue gas recycling pipeline, and a furnace above the capacity expansion area flue gas recycling pipeline is provided with a conical section;
the third layer of recirculation pipeline is positioned between the high-temperature convection superheater and the low-temperature convection superheater, is a convection area flue gas recirculation pipeline and is used for further increasing the capacity and reducing the temperature of the flue gas.
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| CN115653711A (en) * | 2022-09-23 | 2023-01-31 | 山东电力工程咨询院有限公司 | Nuclear power and thermal power coupling power generation system and operation method |
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| CN102174904A (en) * | 2011-03-08 | 2011-09-07 | 上海宁松热能环境工程有限公司 | Method and system for generating power jointly by nuclear fuel and fossil fuel |
| CN102330967A (en) * | 2011-10-24 | 2012-01-25 | 中国电力工程顾问集团华东电力设计院 | Flue gas energy cascade utilization system |
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