CN108678822B - Novel supercritical CO suitable for coal-fired power generation field2Composite circulation system - Google Patents
Novel supercritical CO suitable for coal-fired power generation field2Composite circulation system Download PDFInfo
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- CN108678822B CN108678822B CN201810384183.XA CN201810384183A CN108678822B CN 108678822 B CN108678822 B CN 108678822B CN 201810384183 A CN201810384183 A CN 201810384183A CN 108678822 B CN108678822 B CN 108678822B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
- F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
- F01K25/103—Carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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- F01K21/00—Steam engine plants not otherwise provided for
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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
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Abstract
The invention discloses a novel supercritical CO suitable for the field of coal-fired power generation, belonging to the field of high-efficiency power generation equipment2A composite circulation system. The composite circulating system consists of a top circulating system, a bottom circulating system and an air preheater heat absorption system, and the three systems absorb heat generated by coal combustion in the boiler together. The top cycle is a secondary reheat recompression cycle, the bottom cycle is a staged heating cycle and consists of a bottom cycle cooler, a bottom cycle first compressor, a bottom cycle low-temperature heat regenerator, a bottom cycle second compressor shunt valve, a bottom cycle second compressor, a bottom cycle high-temperature heat regenerator, a first tail flue heater shunt valve, a first tail flue heater, a bottom cycle first turbine, a second tail flue heater and a bottom cycle second turbine, and the bottom cycle can enable the efficiency of the composite cycle system to be higher when the inlet temperature of the top cycle turbine is within the range of 580-640 ℃. And the safe operation of the air preheater is ensured.
Description
Technical Field
The invention belongs to the field of high-efficiency power generation equipment, and particularly relates to novel supercritical CO suitable for the field of coal-fired power generation2A composite circulation system.
Technical Field
Supercritical carbon dioxide Brayton cycle (S-CO)2Circulation) in recent years, research has been widely conducted in the fields of sodium-cooled fast reactor power generation, tower-type solar photo-thermal power generation, gas turbine flue gas waste heat utilization and the like. This study was conducted under conditions where the related art of steam Rankine cycle is mature because S-CO is compared to steam Rankine cycle2Recycling can provide some very attractive advantages.
For example S-CO at the same turbine inlet temperature2The cycle can have higher efficiency in the medium temperature region (550 ℃ -700 ℃) than a steam rankine cycle. In addition CO2Chemically inert, a very stable substance, and the possibility of CO generation2Corrosion with the pipe wall is reduced. S-CO is therefore compared to a steam Rankine cycle under the same material conditions2The turbine inlet temperature of the cycle may be further increased, thereby increasing cycle efficiency. So that S-CO2The cycle has a higher potential in terms of efficiency improvement.
At present, coal-fired power generation provides stable and sufficient power supply for the world, the coal-fired power generation accounts for 39.3 percent of the total amount of global power generation, and according to statistics of British oil companies, the use of coal can last for 153 years and is far higher than that of oil and natural gas. Although the pressure of resources, environment and climate change makes coal-fired power generation face the challenge, the current situation of the dominance of coal-fired power generation in various power generation technologies still does not change in the short term and the middle term. Therefore, the exploration and popularization of the high-efficiency and clean coal-fired power generation technology still have important significance. Reacting S-CO2The cyclic application of the method to the field of coal-fired power generation is a new exploration on the coal-fired power generation technology.
But the reaction of S-CO2When the circulating application is applied to the field of coal-fired power generation, the problem of tail flue gas waste heat can be met, the problem is generated and related to circulating arrangement, and S-CO with the same turbine inlet parameter2Compared with the traditional steam Rankine cycle, the recompression cycle CO is2The temperature of the working medium at the boiler inlet is higher due to the flue gas and CO at the boiler inlet2Working medium needs to ensure a certain temperature difference, so CO2The fact that the temperature of the working medium at the inlet of the boiler is high means that the temperature of the flue gas at the inlet of the boiler is also high, so that the tail flue gas waste heat of the boiler is high, and for Rankine cycle, when the unit is a double-reheating ultra-supercritical unit, the temperature of the inlet water of the economizer (the temperature of the water at the inlet of the boiler) is about 340 ℃, but for Brayton cycle, the temperature is higher. Compared with Rankine cycle, the method has the advantages that the CO is recompressed under the condition of the same temperature and pressure parameters2The temperature in this place is-410 ℃, and when the cycle is adopted twiceThis temperature was 510 ℃ in the thermal arrangement. Therefore S-CO2The tail flue of the unit boiler has a large amount of waste heat. The inability to efficiently absorb the excess heat increases the amount of heat that the boiler emits into the environment, reducing boiler efficiency and thus the overall efficiency of the thermodynamic system. This is S-CO2The waste heat problem faced by coal-fired power generation.
This problem can be solved through constructing the combined cycle, but the effect that different combined cycles were solved is different, if the combined cycle constructs unreasonablely then can reduce system generating efficiency, and system generating efficiency's reduction can be understood from two aspects, 1, if the flue gas waste heat can not be absorbed fully, then generating system boiler efficiency can reduce, 2, the flue gas waste heat obtains absorbing, but the circulation efficiency is lower, and generating system's cyclic heat efficiency can reduce like this.
According to S-CO2The characteristic of coal-fired power generation, we propose a class suitable for S-CO2The utility model discloses a coal-fired power generation's a kind of combined cycle, wherein combined cycle's end circulation is proposed for the first time for this patent, and this circulation can make the thermal efficiency of circulation higher when the high efficiency absorbs flue gas waste heat, so this circulation can both realize reasonable, the high-efficient electricity generation in an extensive warm area.
Disclosure of Invention
In light of the problems noted in the background, the present invention provides a novel supercritical CO suitable for use in the field of coal-fired power generation2Composite circulation system, characterized in that, includes: the heat absorption system comprises a top circulation system, a bottom circulation system and an air preheater heat absorption system, wherein heaters in the top circulation system are arranged in a hearth, a horizontal flue and a front section of a tail flue, the heaters of the bottom circulation system are arranged in a middle section of the tail flue of a boiler, smoke firstly flows through the top circulation system and then flows through the bottom circulation system, the smoke flowing through the bottom circulation system enters the air preheater heat absorption system in the rear section of the tail flue, heat generated by coal combustion is firstly absorbed by the top circulation system, heat which cannot be completely absorbed by the top circulation system is absorbed by the bottom circulation system, and waste heat contained in the smoke exhausted by the bottom circulation system is absorbed by air in the air preheater heat absorption system.
The top circulation system comprises: the system comprises a top circulation cooler, a top circulation first compressor, a top circulation low-temperature heat regenerator, a top circulation second compressor shunt valve, a top circulation second compressor, a top circulation high-temperature heat regenerator, a top circulation boiler first heater, a top circulation first turbine, a top circulation boiler second heater, a top circulation second turbine, a top circulation boiler third heater and a top circulation third turbine; the first heater of the top circulation boiler, the second heater of the top circulation boiler and the third heater of the top circulation boiler are arranged in the front sections of a boiler hearth, a horizontal flue and a tail flue, and an outlet of the first heater of the top circulation boiler is sequentially connected with an inlet and an outlet of a first top circulation turbine, an inlet and an outlet of a second heater of the top circulation boiler, an inlet and an outlet of a second top circulation turbine, an inlet and an outlet of a third heater of the top circulation boiler, an inlet and an outlet of a third top circulation turbine, an inlet and an outlet of a low-pressure side of a high-temperature top circulation regenerator and an inlet and an outlet of a low-pressure side of a low; the outlet of the working medium pipeline at the low-pressure side of the top-circulation low-temperature heat regenerator is respectively connected with the top-circulation cooler and the shunt valve of the top-circulation second compressor, wherein the outlet of the top-circulation cooler, the inlet and the outlet of the top-circulation first compressor are sequentially connected with the inlet of the high-pressure side of the top-circulation low-temperature heat regenerator, the shunt valve of the top-circulation second compressor is connected with the inlet of the top-circulation second compressor, the outlet of the high-pressure side of the top-circulation low-temperature heat regenerator is converged with the outlet of the top-circulation second compressor and then connected with the inlet of the high-pressure side of the top-circulation high-temperature heat regenerator, and the outlet of the high-pressure side of.
The flow through the second compressor diverter valve accounts for 33.21-31.64% of the total flow.
The inlet temperatures of a first heater of a top circulation boiler, a second heater of the top circulation boiler and a third heater of the top circulation boiler in the top circulation system are the same;
the outlet temperatures of the first heater of the top circulation boiler, the second heater of the top circulation boiler and the third heater of the top circulation boiler in the top circulation system are all between 580-640 ℃; the outlet temperature of the second back flue heater in the bottom circulation system is in the range of 486-.
The bottom circulation system includes: the system comprises a bottom circulation cooler, a bottom circulation first compressor, a bottom circulation low-temperature heat regenerator, a bottom circulation second compressor shunt valve, a bottom circulation second compressor, a bottom circulation high-temperature heat regenerator, a first tail flue heater shunt valve, a first tail flue heater, a bottom circulation first turbine, a second tail flue heater and a bottom circulation second turbine; wherein the first tail flue heater and the second tail flue heater are arranged in the tail flue of the boiler; an outlet of the first tail flue heater is converged with an outlet of the high-pressure side of the bottom circulation high-temperature heat regenerator and then is connected with an inlet of a bottom circulation first turbine, and an outlet of the bottom circulation first turbine, an inlet and an outlet of a second tail flue heater, an inlet and an outlet of a bottom circulation second turbine and an inlet and an outlet of the low-pressure side of the bottom circulation high-temperature heat regenerator are sequentially connected with an inlet of a working medium pipeline of the low-pressure side of the bottom circulation low-temperature heat regenerator; the outlet of the low-pressure side working medium pipeline of the bottom circulation low-temperature heat regenerator is respectively connected with a bottom circulation cooler and a bottom circulation second compressor shunt valve, the outlet of the bottom circulation cooler is sequentially connected with the inlet and outlet of a bottom circulation first compressor and the high-pressure side inlet of the bottom circulation low-temperature heat regenerator, the bottom circulation second compressor shunt valve is connected with the inlet of the bottom circulation second compressor, the high-pressure side outlet of the bottom circulation low-temperature heat regenerator is converged with the outlet of the bottom circulation second compressor and then respectively connected with the high-pressure side inlet of the bottom circulation high-temperature heat regenerator and the inlet of a first tail flue heater shunt valve, and the outlet of the first tail flue heater shunt valve is connected with the inlet of the first tail flue heater.
The second tail flue heater and the first tail flue heater are arranged in parallel or arranged up and down in the tail flue;
when the second back pass heater and the first back pass heater are arranged up and down in the back pass, the first back pass heater is below and closer to the pass outlet
The flow passing through the first tail flue heater diverter valve accounts for 9.82-11.38% of the total flow.
The air preheater heat absorption system comprises: a primary air fan, a secondary air fan and an air preheater; wherein the primary fan and the secondary fan are connected with the external environment, the outlet of the primary fan and the outlet of the secondary fan are respectively connected with the primary air inlet and the secondary air inlet of the air preheater, the primary air outlet of the air preheater is connected with the pulverizing system of the boiler, the secondary air outlet of the air preheater is connected with the boiler furnace,
the primary air proportion in the air preheater is 19%, the highest temperature of the primary air is 320 ℃, the secondary air proportion in the air preheater is 81%, and the highest temperature of the secondary air is 380 ℃.
The flue gas cooled by the heat absorption system of the air preheater is 115-125 ℃.
The invention has the beneficial effects that:
the invention is directed to converting supercritical CO2The Brayton cycle is applied to the field of coal-fired power generation, and provides a novel supercritical CO suitable for the field of coal-fired power generation2The combined circulation system can fully absorb heat generated by coal combustion in the boiler through the combined action of the top circulation system, the bottom circulation system and the air preheater heat absorption system.
The heat generated by coal combustion is firstly absorbed by the top circulating system, the heat which can not be completely absorbed by the top circulating system is absorbed by the bottom circulating system, the waste heat contained in the flue gas discharged by the bottom circulating system is absorbed by air in the heat absorption system of the air preheater, and finally the flue gas is cooled to about 120 ℃ and then is discharged to the environment.
The system is characterized in that the second tail flue heater inlet and outlet CO of the bottom circulating system2The temperature difference of the working medium is small, when the inlet pressure of the first turbine of the bottom cycle is 20MPa, the temperature difference can be lower by about 28 ℃ than that of the recompression cycle and by about 100 ℃ than that of the single-heat-recovery Brayton cycle, the characteristic enables the cycle to be suitable for the working condition that the inlet temperature of the top cycle turbine is slightly lower, the reasonable and efficient power generation of the composite cycle can be realized in a wide temperature zone with the inlet temperature of the top cycle turbine between 580 and 640 ℃, and the volume of the air preheater can be maintained at the level which can be realized by the prior art.
The compound circulation solves the problem of S-CO2The problem of tail flue waste heat in coal-fired power generation is solved, and the boiler efficiency and the cycle efficiency of a power generation system are both high, so that the system is high-efficiency S-CO2Coal-fired power generation combined cycle system.
Drawings
FIG. 1 shows a novel supercritical CO suitable for the field of coal-fired power generation2A flow diagram of a combined cycle system embodiment;
in the figure: 1-top cycle cooler, 2-top cycle first compressor, 3-top cycle low temperature regenerator, 4-top cycle second compressor diverter valve, 5-top cycle second compressor, 6-top cycle high temperature regenerator, 7-top cycle boiler first heater, 8-top cycle first turbine, 9-top cycle boiler second heater, 10-top cycle second turbine, 11-top cycle boiler third heater, 12-top cycle third turbine, 213-bottom cycle cooler, 214-bottom cycle first compressor, 215-bottom cycle low temperature regenerator, 216-bottom cycle second compressor diverter valve, 217-bottom cycle second compressor, 218-bottom cycle high temperature regenerator, 219-first tail flue heater diverter valve, 220-first back-end flue heater, 221-bottom cycle first turbine, 222-second back-end flue heater, 223-bottom cycle second turbine, 324-primary fan, 325-secondary fan, 326-air preheater.
Detailed Description
The invention is further explained by combining the attached drawing below, and the novel supercritical CO suitable for the field of coal-fired power generation2An embodiment of a combined cycle system;
as shown in fig. 1, the present embodiment includes: the system comprises a top circulating system 100, a bottom circulating system 200 and an air preheater heat absorption system 300, wherein each heater in the top circulating system 100 is arranged in a hearth, a horizontal flue and the front section of a tail flue, the heater of the bottom circulating system 200 is arranged in the middle section of the tail flue of the boiler, flue gas firstly flows through the top circulating system 100 and then flows through the bottom circulating system 200, the flue gas flowing through the bottom circulating system 200 enters the air preheater heat absorption system 300 in the rear section of the tail flue, and the three systems act together to absorb heat generated by coal combustion in the boiler; burning coal in a hearth of the boiler, and discharging the flue gas after burning into the environment after the flue gas flows through a flue;
the heat generated by coal combustion is firstly absorbed by the top circulation system 100, the heat which cannot be completely absorbed by the top circulation system 100 is absorbed by the bottom circulation system 200, the waste heat contained in the flue gas discharged by the bottom circulation system 200 is absorbed by the air in the air preheater heat absorption system 300, and finally the flue gas is cooled to about 120 ℃ and then is discharged to the environment.
The top circulation system 100 includes: the system comprises a top circulation cooler 1, a top circulation first compressor 2, a top circulation low-temperature heat regenerator 3, a top circulation second compressor shunt valve 4, a top circulation second compressor 5, a top circulation high-temperature heat regenerator 6, a top circulation boiler first heater 7, a top circulation first turbine 8, a top circulation boiler second heater 9, a top circulation second turbine 10, a top circulation boiler third heater 11 and a top circulation third turbine 12; wherein, the first heater 7 of the top circulation boiler, the second heater 9 of the top circulation boiler and the third heater 11 of the top circulation boiler are arranged in the front sections of the hearth, the horizontal flue and the tail flue of the boiler, the outlet of the first heater 7 of the top circulation boiler is connected with the inlet and outlet of the first turbine 8 of the top circulation boiler, the inlet and outlet of the second heater 9 of the top circulation boiler, the inlet and outlet of the second turbine 10 of the top circulation boiler, the inlet and outlet of the third heater 11 of the top circulation boiler, the inlet and outlet of the third turbine 12 of the top circulation boiler, the inlet and outlet of the low-pressure side of the high-temperature regenerator 6 of the top circulation boiler are connected with the inlet of the low; the outlet of a low-pressure side working medium pipeline of the top circulation low-temperature heat regenerator 3 is respectively connected with a top circulation cooler 1 and a top circulation second compressor shunt valve 4, wherein the outlet of the top circulation cooler 1 and the inlet and outlet of a top circulation first compressor 2 are sequentially connected with the high-pressure side inlet of the top circulation low-temperature heat regenerator 3, the top circulation second compressor shunt valve 4 is connected with the inlet of a top circulation second compressor 5, the high-pressure side outlet of the top circulation low-temperature heat regenerator 3 is connected with the high-pressure side inlet of a top circulation high-temperature heat regenerator 6 after being converged with the outlet of the top circulation second compressor 5, and the high-pressure side outlet of the top circulation high-temperature heat regenerator 6 is connected with the inlet of a top circulation boiler first heater;
the top circulation system 100 is a double reheat recompression cycle with high cycle efficiency, and the top circulation system 100 absorbs about 90% of heat generated by coal combustion.
The bottom circulation system 200 includes: a bottom cycle cooler 213, a bottom cycle first compressor 214, a bottom cycle low temperature regenerator 215, a bottom cycle second compressor diverter valve 216, a bottom cycle second compressor 217, a bottom cycle high temperature regenerator 218, a first tail flue heater diverter valve 219, a first tail flue heater 220, a bottom cycle first turbine 221, a second tail flue heater 222, and a bottom cycle second turbine 223; wherein the first back pass heater 220 and the second back pass heater 222 are disposed within the boiler back pass; an outlet of the first tail flue heater 220 is converged with an outlet of a high-pressure side of the bottom circulation high-temperature heat regenerator 218 and then is connected with an inlet of a first bottom circulation turbine 221, an outlet of the first bottom circulation turbine 221, an inlet and an outlet of a second tail flue heater 222, an inlet and an outlet of a second bottom circulation turbine 223 and an inlet and an outlet of a low-pressure side of the bottom circulation high-temperature heat regenerator 218 are sequentially connected with an inlet of a low-pressure side working medium pipeline of the bottom circulation low-temperature heat regenerator 215; the outlet of the low-pressure side working medium pipeline of the bottom circulation low-temperature heat regenerator 215 is respectively connected with a bottom circulation cooler 213 and a bottom circulation second compressor shunt valve 216, the outlet of the bottom circulation cooler 213 is sequentially connected with the inlet and outlet of a bottom circulation first compressor 214 and the high-pressure side inlet of the bottom circulation low-temperature heat regenerator 215, the bottom circulation second compressor shunt valve 216 is connected with the inlet of a bottom circulation second compressor 217, the high-pressure side outlet of the bottom circulation low-temperature heat regenerator 215 is converged with the outlet of the bottom circulation second compressor 217 and then respectively connected with the high-pressure side inlet of a bottom circulation high-temperature heat regenerator 218 and the inlet of a first tail flue heater shunt valve 219, and the outlet of the first tail flue heater shunt valve 219 is connected with the inlet of a first tail flue heater 220.
In this embodiment, the first back flue heater 220 and the second back flue heater 222 in the bottom circulation system 200 are arranged in parallel in the back flue, and the CO at the inlet and outlet of the second back flue heater 2222The temperature difference of the working medium is small, when the inlet pressure of the first turbine 221 of the bottom cycle is 20MPa, the temperature difference can be lower by about 28 ℃ than that of the recompression cycle and by about 100 ℃ than that of the single-heat-recovery Brayton cycle, and the characteristic enables the bottom cycle system to be suitable for the working condition with the temperature slightly lower than that of the inlet of the top cycle turbine. Bottom circulation flowThe amount of the catalyst accounts for 10.90 to 13.21 percent of the total flow of the top circulation and the bottom circulation; it should be noted that in this embodiment, the second back flue heater 222 and the first back flue heater 220 may also be arranged up and down, and at this time, the flue gas passes through the second back flue heater 222 and then passes through the first back flue heater 220.
The bottom circulation system 200 is a staged heating circulation and is a new circulation heating mode, and the bottom circulation can ensure that the efficiency of the composite circulation system is higher when the outlet temperature of the top circulation turbine (the first heater 7 of the top circulation boiler, the second heater 9 of the top circulation boiler and the third heater 11 of the top circulation boiler) is in the range of 580 ℃ to 640 ℃; the inlet temperature range of the first heater 7 of the top circulation boiler in the top circulation system 100 is 486-; any of the two inlet temperature ranges above may be the optimal operating temperature range for the bottoming cycle system 200; when the temperature range of 486-.
The air preheater heat absorption system 300 includes: primary fan 324, secondary fan 325, and air preheater 326; wherein the entry of air heater heat absorption system 300 is external environment, the entry of air heater heat absorption system 300 is the entry of primary air fan 324 and overfire air fan 325, primary air fan 324 links to each other with the overfire air fan 325 entry with external environment, primary air fan 324 export links to each other with the primary air entry and the overfire air entry of air heater 326 respectively with the overfire air 325 export, air heater 326 primary air export links to each other with the powder process system of boiler, air heater 326 overfire air export links to each other with boiler furnace, air heater 326 overfire air passes through the overfire air spout and gets into boiler furnace, provide sufficient air for the burning of coal. The primary air accounts for about 19% in the air preheater, the highest temperature of the primary air is about 320 ℃, the secondary air accounts for about 81%, and the highest temperature of the secondary air is 380 ℃.
In the embodiment, the working process of the supercritical carbon dioxide working medium in the circulating system is divided into a top circulation part and a bottom circulation part;
the top circulation work flow is as follows: the supercritical carbon dioxide working medium is shunted at the outlet of the working medium pipeline at the low pressure side of the top circulation low-temperature heat regenerator 3 (the working medium state is at 90.88-95.24 ℃, and 7.70MPa at the moment), one path of the working medium flows through the top circulation cooler 1, and the cooled CO flows through the top circulation cooler 12The working medium (the state of the working medium is 32.00 ℃ C., 7.60MPa) enters the top circulation first compressor 2, after being compressed in the top circulation first compressor 2 (the state of the working medium is 80.88-85.24 ℃ C., 30.05-33.28MPa), the working medium enters the high pressure side of the top circulation low-temperature heat regenerator 3, and CO is respectively arranged in the high pressure side and the low temperature side of the top circulation low-temperature heat regenerator 32The other path of working medium exchanges heat, enters a top circulation second compressor 5 after flowing through a top circulation second compressor shunt valve 4 (the state of the working medium is 90.88-95.24 ℃, 7.70MPa, and the flow rate flowing through the second compressor shunt valve 4 accounts for 33.21-31.64% of the total flow rate), is compressed in the top circulation second compressor 5 and then is converged with the working medium at the high-pressure side of the top circulation low-temperature regenerator 3 (the state of the working medium is 227.46-244.45 ℃, 29.95-33.18MPa), the converged working medium enters the high-pressure side of the top circulation high-temperature regenerator 6, enters a top circulation boiler first heater 7 after exchanging heat with the working medium at the low-pressure side (the state of the working medium is 486.31-535.27 ℃, 29.85-33.08MPa), and enters a top circulation first turbine 8 after the top circulation boiler first heater 7 absorbs the heat generated by the combustion of coal in the boiler (the state of the working medium is 580.00-640.00 ℃, 28.00-32.00MPa), after acting in the top-cycle first turbine 8 (at this time, the state of the working medium is: 524.16-575.52 ℃ and 18.36-20.07MPa) enters a second heater 9 of the top circulation boiler to absorb heat generated by coal combustion in the boiler, and working media after heat absorption (at the moment, the states of the working media are as follows: 580.00-640.00 ℃ and 18.11-19.89MPa) into the top-cycle second turbine 10, and after the top-cycle second turbine 10 does work (at this time, the working medium state is: 526.93-577.84 ℃ and 12.04-12.59MPa) enters the roofThe third heater 11 of the circulating boiler absorbs the heat generated by the coal combustion in the boiler, the working medium (at the moment, the state of the working medium is 580.00-640.00 ℃, 11.71-12.36MPa) after absorbing the heat enters the third top circulating turbine 12, the working medium (at the moment, the state of the working medium is 529.51-580.09 ℃, 7.90MPa) enters the low-pressure side of the high-temperature regenerator 6 of the top circulating after acting in the third top circulating turbine 12, the heat is transferred to the low-pressure side, and the CO after heat transfer enters the low-pressure side2Working medium (at the moment, the working medium state is 237.46-254.45 ℃, 7.80MPa) enters the low-pressure side of the top-cycle low-temperature regenerator 3 to transfer heat to the high-pressure side, and then CO flows to the high-pressure side2The working medium completes one cycle in the top cycle; the temperature of the flue gas decreases after passing through the top circulation (the temperature range of the flue gas is 564.16-615.52 ℃).
About 90% of heat in the furnace can be absorbed by the first heater 7 of the top circulation boiler, the second heater 9 of the top circulation boiler and the third heater 11 of the top circulation boiler in the top circulation. The remaining heat will then be further absorbed by the bottom circulation system.
The bottom circulation work flow is as follows: the supercritical carbon dioxide working medium is divided at the outlet of the working medium pipeline (the working medium state is 67.42-81.22 ℃ and 7.70MPa) at the low-pressure side of the bottom circulation low-temperature heat regenerator 215, wherein one part of the working medium flows through the bottom circulation cooler 213, and the cooled CO flows through the bottom circulation cooler 2132The working medium (the state of the working medium is 32.00 ℃ C., 7.60MPa) enters the bottom circulation first compressor 214, after being compressed in the bottom circulation first compressor 214 (the state of the working medium is 57.42-71.22 ℃ C., 16.26-23.66MPa), the working medium enters the high pressure side of the bottom circulation low-temperature heat regenerator 215, and CO enters the high pressure side and the low temperature side of the bottom circulation low-temperature heat regenerator 2152The working medium exchanges heat, the other path enters the bottom circulation second compressor 217 after flowing through the bottom circulation second compressor shunt valve 216 (the state of the working medium is 67.42-81.22 ℃, 7.70MPa, and the flow rate flowing through the second compressor shunt valve 4 accounts for 45.41-37.19% of the total flow rate), the working medium is compressed in the bottom circulation second compressor 217 and then is converged with the working medium at the high-pressure side outlet of the bottom circulation low-temperature heat regenerator 215 (the state of the working medium is 134.88-189.56 ℃, 16.16-23.56MPa at this time), the converged working medium is shunted again, wherein one path of fluid flows through the first tail flue heater shunt valve 219 (the first tail flue heater shunt valve)The flow through the door 219 accounts for 9.82-11.38% of the total flow) enters the first tail flue heater 220 to absorb heat, and the other path of CO enters the first tail flue heater 220 to absorb heat2The working medium enters the high-pressure side of the bottom-cycle high-temperature heat regenerator 218 to absorb the heat transferred from the low-pressure side, and the CO absorbed by the first tail flue heater 220 and the outlet of the bottom-cycle high-temperature heat regenerator 2182The working medium is converged (at the moment, the working medium state is 434.77-458.78 ℃, 16.06-23.46MPa), the converged working medium enters a bottom circulation first turbine 221 to do work, and the CO after doing work2Working medium (at the moment, the working medium is in the state of 395.23-395.31 ℃ and 11.29-13.66MPa) enters the second tail flue heater 222 to absorb the waste heat of the flue gas in the boiler, the working medium (at the moment, the working medium is in the state of 486.31-535.27 ℃ and 11.19-13.56MPa) after absorbing heat enters the bottom circulation second turbine 223 to do work, the working medium after doing work enters the low-pressure side of the bottom circulation high-temperature regenerator 218 (at the moment, the working medium is in the state of 444.75-468.77 ℃ and 7.90MPa) to transfer heat to the working medium at the high-pressure side, and CO after releasing heat transfers the heat2The working medium enters the low-pressure side of the bottom-cycle low-temperature regenerator 215 (the state of the working medium is 144.88-199.56 ℃ and 7.80MPa at the moment), and heat is transferred to the working medium at the high-pressure side, so that CO flows to the working medium at the high-pressure side2The working medium completes one cycle in the bottom cycle; the temperature of the flue gas is reduced after the flue gas flows through the bottom circulation (the temperature of the flue gas is about 430 ℃ and 440 ℃).
Second back flue heater 222 inlet-outlet CO of bottom circulation system 2002The temperature difference of the working medium is small, when the inlet pressure of the first turbine 221 of the bottom cycle is 20MPa, the temperature difference can be lower by about 28 ℃ than that of a recompression cycle and by about 100 ℃ than that of a single-heat-recovery Brayton cycle, and the cycle is suitable for the working condition that the inlet temperature of the top cycle turbine is slightly lower. The bottom circulation flow accounts for 10.90-13.21% of the total flow of the top circulation and the bottom circulation.
Flue gas in bottom circulation2After the working medium absorbs heat, a part of heat is remained and is absorbed by an air preheater system, air and smoke flow in the air preheater, the smoke transfers the heat to the air, the air after heat absorption is divided into primary air and secondary air, wherein the primary air enters a powder making system to carry pulverized coal to enter a hearth for combustion, and the secondary air enters a combustor to assist coal combustion.
The primary air fan 324 and the secondary air fan 325 absorb air from the external environment, the air is sent into an air preheater 326 (at the moment, the primary air temperature is 31.00 ℃, and the secondary air temperature is 21.00 ℃) to exchange heat with flue gas, the primary air (at the moment, the primary air temperature is 320.00 ℃) after heat absorption enters a pulverizing system and carries pulverized coal to enter a boiler, and the secondary air (at the moment, the secondary air temperature is 380.00 ℃) after heat absorption enters a combustor for supporting combustion. The temperature of the flue gas cooled by air is about 115-125 ℃, and finally the residual heat in the flue gas is discharged into the environment as waste heat.
Claims (7)
1. Novel supercritical CO suitable for coal-fired power generation field2Composite circulation system, characterized in that, includes: the system comprises a top circulation system (100), a bottom circulation system (200) and an air preheater heat absorption system (300), wherein each heater in the top circulation system (100) is arranged in the front sections of a boiler hearth, a horizontal flue and a tail flue, the heater of the bottom circulation system (200) is arranged in the middle section of the tail flue of the boiler, flue gas firstly flows through the top circulation system (100) and then flows through the bottom circulation system (200), the flue gas flowing through the bottom circulation system (200) enters the air preheater heat absorption system (300) in the rear section of the tail flue, heat generated by coal combustion is firstly absorbed by the top circulation system (100), heat which cannot be completely absorbed by the top circulation system (100) is absorbed by the bottom circulation system (200), and waste heat contained in the flue gas exhausted by the bottom circulation system (200) is absorbed by air in the air preheater heat absorption system (300;
the bottom circulation system (200) comprises: the system comprises a bottom circulation cooler (213), a bottom circulation first compressor (214), a bottom circulation low-temperature regenerator (215), a bottom circulation second compressor shunt valve (216), a bottom circulation second compressor (217), a bottom circulation high-temperature regenerator (218), a first tail flue heater shunt valve (219), a first tail flue heater (220), a bottom circulation first turbine (221), a second tail flue heater (222) and a bottom circulation second turbine (223); wherein the first back pass heater (220) and the second back pass heater (222) are disposed within the boiler back pass; an outlet of the first tail flue heater (220) is converged with an outlet at the high-pressure side of the bottom circulation high-temperature regenerator (218) and then is connected with an inlet of a first turbine (221) of the bottom circulation, an outlet of the first turbine (221) of the bottom circulation, an inlet and an outlet of a second tail flue heater (222), an inlet and an outlet of a second turbine (223) of the bottom circulation, and an inlet and an outlet at the low-pressure side of the bottom circulation high-temperature regenerator (218) are sequentially connected with an inlet at the low-pressure side of the bottom circulation low-temperature regenerator (215); the outlet of the low-pressure side of the bottom circulation low-temperature regenerator (215) is respectively connected with a bottom circulation cooler (213) and a bottom circulation second compressor shunt valve (216), the outlet of the bottom circulation cooler (213) is sequentially connected with the inlet and outlet of a bottom circulation first compressor (214) and the high-pressure side inlet of the bottom circulation low-temperature regenerator (215), the bottom circulation second compressor shunt valve (216) is connected with the inlet of a bottom circulation second compressor (217), the high-pressure side outlet of the bottom circulation low-temperature regenerator (215) is converged with the outlet of the bottom circulation second compressor (217) and then respectively connected with the high-pressure side inlet of a bottom circulation high-temperature regenerator (218) and the inlet of a first tail flue heater shunt valve (219), and the outlet of the first tail flue heater shunt valve (219) is connected with the inlet of a first tail flue heater (220);
the flow flowing through the first tail flue heater shunt valve (219) accounts for 9.82% -11.38% of the total flow;
the working medium compressed in the bottom circulation second compressor (217) is converged with the working medium at the outlet of the high-pressure side of the bottom circulation low-temperature heat regenerator (215), the converged working medium is divided again, and one path of CO is divided into two paths of CO2Working medium enters a first tail flue heater (220) through a first tail flue heater shunt valve (219) to absorb heat, and the other path of CO enters a second tail flue heater (220)2The working medium enters the high-pressure side of the bottom-cycle high-temperature heat regenerator (218) to absorb heat transferred by the low-pressure side, and CO absorbed by the high-pressure side outlet of the bottom-cycle high-temperature heat regenerator (218) and the first tail flue heater (220) is heated2The working media are converged, the converged working media enter a bottom circulation first turbine (221) to do work, and the worked CO2The working medium enters a second tail flue heater (222) to absorb the waste heat of the flue gas in the boiler, and the working medium after heat absorption enters the bottomThe second turbine (223) works circularly, and the working medium which does work enters the low-pressure side of the bottom-cycle high-temperature heat regenerator (218) to transfer heat to the working medium at the high-pressure side;
the top circulation system (100) comprises: the system comprises a top circulation cooler (1), a top circulation first compressor (2), a top circulation low-temperature heat regenerator (3), a top circulation second compressor shunt valve (4), a top circulation second compressor (5), a top circulation high-temperature heat regenerator (6), a top circulation boiler first heater (7), a top circulation first turbine (8), a top circulation boiler second heater (9), a top circulation second turbine (10), a top circulation boiler third heater (11) and a top circulation third turbine (12); the top circulation boiler first heater (7), the top circulation boiler second heater (9) and the top circulation boiler third heater (11) are arranged in the front sections of a boiler hearth, a horizontal flue and a tail flue, and an outlet of the top circulation boiler first heater (7) is sequentially connected with an inlet and an outlet of a top circulation first turbine (8), an inlet and an outlet of the top circulation boiler second heater (9), an inlet and an outlet of a top circulation second turbine (10), an inlet and an outlet of the top circulation boiler third heater (11), an inlet and an outlet of a top circulation third turbine (12), an inlet and an outlet of a low-pressure side of a top circulation high-temperature regenerator (6) and an inlet of a low-pressure side of a top circulation low-temperature regenerator (3); the outlet of the low-pressure side of the top-circulation low-temperature regenerator (3) is respectively connected with the top-circulation cooler (1) and the shunt valve (4) of the top-circulation second compressor, wherein the outlet of the top-circulation cooler (1), the inlet and the outlet of the top-circulation first compressor (2) are sequentially connected with the inlet of the high-pressure side of the top-circulation low-temperature regenerator (3), the shunt valve (4) of the top-circulation second compressor is connected with the inlet of the top-circulation second compressor (5), the outlet of the high-pressure side of the top-circulation low-temperature regenerator (3) is converged with the outlet of the top-circulation second compressor (5) and then connected with the inlet of the high-pressure side of the top-circulation high-temperature regenerator (6), and the outlet of the high-pressure side of the top-circulation high-temperature regenerator (6) is connected with the inlet of.
2. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 12The compound circulation system is characterized in that the flow rate flowing through the top circulation second compressor shunt valve (4) accounts for 31.64% -33.21% of the total flow rate.
3. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 12The combined cycle system is characterized in that the outlet temperatures of a first heater (7) of a top cycle boiler, a second heater (9) of the top cycle boiler and a third heater (11) of the top cycle boiler in the top cycle system (100) are all between 580 and 640 ℃; the outlet temperature of the second back flue heater (222) in the bottom circulation system (200) is in the range of 486-578 ℃.
4. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 12The combined circulation system is characterized in that the second tail flue heater (222) and the first tail flue heater (220) are arranged in parallel or arranged up and down in the tail flue;
the first back flue heater (220) is below and closer to the flue outlet when the second back flue heater (222) and the first back flue heater (220) are arranged up and down in the back flue.
5. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 12A combined cycle system, characterized in that the air preheater heat absorption system (300) comprises: a primary air fan (324), a secondary air fan (325), and an air preheater (326); the primary air fan (324) and the secondary air fan (325) are connected with the external environment, the outlet of the primary air fan (324) and the outlet of the secondary air fan (325) are respectively connected with the primary air inlet and the secondary air inlet of the air preheater (326), the primary air outlet of the air preheater (326) is connected with a pulverizing system of a boiler, and the secondary air outlet of the air preheater (326) is connected with a boiler hearth.
6. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 52The composite circulation system is characterized in that the primary air proportion in the air preheater (326) is 19%, the highest temperature of the primary air is 320 ℃, the secondary air proportion in the air preheater (326) is 81%, and the highest temperature of the secondary air is 380 ℃.
7. The novel supercritical CO suitable for the field of coal-fired power generation according to claim 12The combined cycle system is characterized in that the temperature of the flue gas cooled by the air preheater heat absorption system (300) is 115-125 ℃.
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| CN111005780B (en) * | 2019-12-19 | 2021-06-18 | 华北电力大学 | Supercritical CO for thoroughly solving waste heat problem2Coal-fired power generation system |
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