CN107906498B - Supercritical carbon dioxide circulating fluidized bed combustion coal boiler and its electricity generation system of driving - Google Patents

Abstract

The invention discloses a supercritical carbon dioxide circulating fluidized bed coal-fired boiler, which uses supercritical carbon dioxide instead of steam in the existing circulating fluidized bed boiler as a working medium for absorbing heat and doing work, and the heat absorbing process of the working medium includes one split flow and one reheating . The working medium heating surface of supercritical carbon dioxide circulating fluidized bed boiler includes carbon dioxide cold wall panel heater and high temperature reheater installed in the furnace; The upper-level economizer is installed; the heating surface along the flue gas flow direction in the tail flue includes a low-temperature reheater and a lower-level economizer. The invention also discloses a power generation system for driving and generating electricity by the supercritical carbon dioxide circulating fluidized bed coal-fired boiler. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler of the present invention strengthens the flue gas heat transfer in the high temperature section of the reheater, and at the same time eases the heat demand pressure of the tail flue, which can effectively reduce the emission of pollutants and the exhaust gas temperature. Increase boiler efficiency.

Description

Supercritical carbon dioxide circulating fluidized bed coal-fired boiler and its driven power generation system

technical field

The invention belongs to the field of thermal power generation equipment, and in particular relates to a supercritical carbon dioxide circulating fluidized bed coal-fired boiler and a power generation system driven by the same.

Background technique

Improving energy conversion rate, reducing pollutant emissions, and developing new environmentally friendly energy sources are the eternal themes of the thermal power industry. The traditional boiler system uses steam as the circulating working medium to realize energy conversion, and the efficiency can only reach about 50% when the steam parameters are increased to 700°C. However, at present, it is difficult and costly to develop alloy materials that can withstand high temperatures of 700°C. Therefore, the high temperature resistance of materials has become a major bottleneck that limits the efficient power generation of power plants.

Supercritical carbon dioxide is a kind of supercritical fluid, its temperature and pressure are above the critical point, and it remains in the gas phase after heating and cooling without phase change. In the case of the same temperature of the turbine inlet working medium, the power generation efficiency of the boiler system using supercritical carbon dioxide as the circulating working medium is higher than that of the boiler system using steam as the circulating working medium. Supercritical carbon dioxide coal-fired thermal power generation can achieve the efficiency of heating to 700°C with steam as the working medium in the temperature range of 620°C, without the need to develop high-temperature resistant alloys, and supercritical carbon dioxide has high energy density, high heat transfer efficiency, and low energy consumption. The amount of coal is low, and supercritical carbon dioxide coal-fired thermal power generation has extremely broad application prospects.

In the past two decades, the research on supercritical carbon dioxide by scholars at home and abroad has mainly focused on the application of supercritical carbon dioxide in the fields of solar energy, nuclear power and fossil energy power generation, while there has been less research on supercritical carbon dioxide coal-fired boilers for high-parameter thermal power. Patent 201510117556.3 uses supercritical carbon dioxide in pulverized coal boilers. However, pulverized coal boilers have a large amount of sewage, and the pollutant treatment they face is under great social and economic pressure. As a high-efficiency, low-pollution and clean coal-fired technology that has developed rapidly in recent decades, circulating fluidized bed boiler technology will undoubtedly become a trend in combination with supercritical carbon dioxide.

Contents of the invention

The purpose of the present invention is to provide a circulating fluidized bed coal-fired boiler that can improve the thermal efficiency of the boiler, reduce pollutant discharge, and realize efficient and clean operation of the boiler, using supercritical carbon dioxide as a circulating working medium, so as to solve the problem of the steam temperature of the existing steam boiler. A problem that limits the improvement of efficiency.

Technical solution: The present invention provides a supercritical carbon dioxide circulating fluidized bed coal-fired boiler, including a supercritical carbon dioxide gas tank, a gas storage station, a membrane supercritical carbon dioxide cold wall, a panel heater, a panel high-temperature reheater, Separator, ash control valve, external upper-level economizer, low-temperature reheater, lower-level economizer and air preheater; membrane supercritical carbon dioxide cold wall, panel heater and panel reheater are installed in the furnace Inside, separators, ash control valves and external upper-level economizers are arranged in sequence along the direction of ash flow at the furnace outlet, and low-temperature reheaters, lower-level economizers and air preheaters are arranged in sequence in the tail flue along the direction of flue gas flow.

The high-temperature reheater is arranged in the furnace in the form of a panel, which enhances the heat transfer of the flue gas in the high-temperature section of the reheater, and also relieves the heat demand pressure of the tail flue.

The gas storage station and the supercritical carbon dioxide gas tank are bidirectionally connected. The flow direction of the working medium between the gas storage station and the supercritical carbon dioxide gas tank depends on the boiler operating load. When the boiler load increases, the working medium flows from the gas storage station to the supercritical carbon dioxide gas tank. In the carbon dioxide gas tank, when the load is reduced, part of the working fluid in the supercritical carbon dioxide gas tank flows into the gas storage station; the inlet of the supercritical carbon dioxide cold wall is connected with the outlet of the high temperature regenerator.

There are only supercritical carbon dioxide cold walls, panel heaters and panel high-temperature reheaters in the furnace. The supercritical carbon dioxide cold walls are arranged along the four walls of the furnace. The front and rear walls are staggered, and the panel heater is composed of a first panel heater and a second panel heater that are connected in parallel and have the same size and structure.

Furnace width D ₁ ; bottom width D ₂ of the dense phase area = 0.55～0.65D ₁ , the height of the cold wall set on the front wall of the furnace is L ₁ , and the height of the cold wall on the rear wall is L ₁ +L ₂ , where L ₂ =0.063～ 0.078L ₁ ; the height of the first panel heater and the second panel heater in the furnace along the length of the furnace is H ₂ =0.22-0.27L ₁ , and the length of the furnace width H ₁ =0.37-0.45H ₂ , and the first panel heater and the second panel heater are located in the middle and upper part of the furnace, the height of the panel high-temperature reheater in the furnace is H ₃ =0.5~0.6H ₂ , and the length H ₄ =0.9~1.1H ₁ .

The separator is a high-temperature adiabatic cyclone separator, and the external upper-level economizer is set in the feeder section between the separator outlet and the furnace, so that the external upper-level economizer uses ash as a heat source; the high-temperature adiabatic cyclone separator includes The first high-temperature adiabatic cyclone separator and the second high-temperature adiabatic cyclone separator are symmetrically arranged in the type high-temperature reheater. The lower part of the first high-temperature adiabatic cyclone separator is provided with an external heating surface, and the lower part of the second high-temperature adiabatic cyclone separator is not arranged for heating noodle. As a result, the temperature of the ash separated into the furnace by the second high-temperature adiabatic cyclone separator does not change substantially, and it belongs to the high-temperature stage ash. Since the ash circulation rate in the present invention is relatively high, the second high-temperature adiabatic cyclone separator can be used to assist the first ash. The high-temperature adiabatic cyclone separator separates and returns circulating ash, and when the load of the boiler changes, it controls the amount of ash entering the high-temperature section of the furnace, so that the heat entering the furnace can adapt to the load of the boiler.

In the tail flue, because the specific volume of the working fluid is small and the temperature rise is small, the heat absorption of the working fluid is small, so the horizontal transition flue at the tail is not equipped with a heating surface, only the heating surface is arranged in the vertical flue, and the flue gas is saved from the lower level. After flowing out of the boiler, it flows to the air preheater to heat the air, so that it can ensure the stable combustion of fuel in the furnace of the supercritical carbon dioxide circulating fluidized bed boiler. The arrangement of the three-stage heating surface at the rear can obviously reduce the exhaust gas temperature and improve the thermal efficiency of the boiler.

The width of the tail flue is D ₃ ; the low-temperature reheater pipe adopts a serpentine pipe arrangement, and the pipe length of the low-temperature reheater in the width direction of the tail flue is smaller than the width of the flue; the outlet of the air preheater and the air distribution plate at the bottom of the furnace It is connected with the upper part of the dense phase area. The tube length of the low-temperature reheater in the width direction of the tail flue is H ₇ =0.7-0.85D ₃ , preferably H ₇ =0.77D ₃ ; the height of the low-temperature reheater along the extension direction of the tail flue is H ₈ =0.76- 0.93D ₃ , preferably H ₈ =0.85D ₃ ; the external upper-level economizer is placed at the lower part of the first high-temperature adiabatic cyclone separator, parallel to the feeder, and controlled by the ash control valve in the heating surface of the external upper-level economizer High-temperature ash content, heating supercritical carbon dioxide from the lower-level economizer, the heating surface width of the external upper-level economizer is H ₅ =1.08～1.3H ₇ , preferably H ₅ =1.2H ₇ , and the heating surface of the external upper-level economizer is high H ₆ =0.54˜0.66H ₈ , preferably H ₆ =0.6H ₈ .

The lower-level economizers are arranged in a staggered arrangement, that is, it includes multiple rows of horizontally arranged pipe rows from top to bottom, each row of pipes includes multiple rows of pipes arranged in parallel, and each row of pipes includes n (n is an integer greater than or equal to 1) vertically arranged row pipes. From top to bottom, the number of tubes in the odd-numbered tube group is the same, and the number of tubes in the even-numbered tube group is the same, and the number of tubes in the odd-numbered tube group is higher than that in the even-numbered tube group. The number of rows of pipes in a group is one more, and the rows of pipes between adjacent groups of pipes are staggered. This arrangement makes the heat transfer coefficient of the lower economizer large and the size reduced. The height H ₉ of the lower economizer is H ₉ =0.99～1.21D ₃ , preferably H ₉ =1.1D ₃ ; the height H ₁₀ of the heating surface of the air preheater along the extension direction of the tail flue is H ₁₀ =1.6～1.91D ₃ , preferably H ₁₀ =1.74D ₃ ; where D ₃ is the flue width. In the lower economizer, the horizontal distance between the pipes of each pipe group is S ₁ =1.8d, and the vertical distance between adjacent pipe groups is S ₂ =2d, where d is the pipe diameter.

The present invention also provides a supercritical carbon dioxide power generation system, which is driven by the supercritical carbon dioxide circulating fluidized bed coal-fired boiler to generate electricity.

The working principle of the present invention is that the source of working fluid on the cold wall of the boiler includes a high-temperature regenerator and a low-temperature regenerator. The primary diverted working fluid pumped from the cold side of the low-temperature regenerator is heated successively through the lower-level economizer and the external upper-level economizer until the final temperature of the undivided working fluid is the same as that heated in the high-temperature regenerator , mixed with the outlet working fluid on the cold side of the high temperature regenerator and flow into the supercritical carbon dioxide cold wall together. After the high temperature regenerator and upper economizer absorb heat, the working fluid mixes and flows into the cold wall of the boiler. The outlet of the cold wall is connected to the inlet of the supercritical carbon dioxide gas tank, and the outlet of the supercritical carbon dioxide gas tank is connected to the inlet of the panel heater. After the working fluid is heated in the inner cold wall of the furnace, all of it flows into the gas box, mixes with the working fluid in the gas box, and flows into the panel heater. After being heated to 600°C, it flows into the high-pressure turbine to release heat and perform work. Supercritical carbon dioxide is exhausted from the high-pressure turbine and enters the low-temperature reheater in the tail flue for reheating. After the outlet temperature of the working medium of the heater is the same, it enters the low-pressure turbine to release heat and do work, so far the working medium completes a cycle of heat absorption in the boiler.

Compared with the prior art, the beneficial effects of the present invention include:

1. The circulating fluidized bed boiler of the present invention adopts supercritical carbon dioxide as the working medium. Compared with the traditional working medium water, the specific volume of supercritical carbon dioxide is smaller under the same temperature and pressure conditions. After the regenerator is heated, the temperature can reach about 525°C, and the initial temperature is high. Therefore, supercritical carbon dioxide is selected as the circulating working medium. Under the same working conditions, the working medium furnace absorbs less heat and the power generation system has high cycle efficiency. The energy density of supercritical carbon dioxide is high, and the size of the turbine and compressor of the power generation system to which it belongs is also reduced accordingly, the amount of metal consumables is small, and the initial economic investment is small. In addition, supercritical carbon dioxide does not undergo a phase change process during the cycle, which eliminates the occurrence of cavitation from the source, and greatly reduces the maintenance costs caused by cavitation in turbines, supercritical carbon dioxide pumps and other devices. Circulating fluidized bed boiler technology is a high-efficiency, low-pollution and clean coal-fired technology that has developed rapidly in recent decades. The combination of furnace and supercritical carbon dioxide undoubtedly has obvious advantages.

2. The panel heater in the furnace is divided into the first panel heater and the second panel heater. The structure is completely symmetrical with respect to the panel reheater, and both of them are staggered with the panel reheater in the furnace, which is beneficial to the panel reheater. The heater and panel reheater can fully absorb the convective radiation heat of flue gas in the furnace, and promote the uniform distribution of heat load in the horizontal section of the furnace.

3. The high-temperature panel reheater is placed in the furnace, and the external upper-level economizer uses the high-temperature ash in the cyclone separator to heat the working medium in the tube. Compared with the high-temperature reheater and upper-level economizer, both are set in the tail flue. The heat transfer coefficient between the heat source and the working medium is greatly enhanced, and the heating area of the heat exchanger can be reduced accordingly, and it can effectively solve the problem that there are many longitudinal tube bundles in the flue at the tail of the large unit due to the excessive flow of the working medium, so that the heating surface cannot Situation set aside.

Description of drawings

Fig. 1(a) is a schematic diagram of the overall structure of a supercritical carbon dioxide circulating fluidized bed boiler; Fig. 1(b) is a front view of the lower economizer; Fig. 1(c) is a partial enlarged left view of the exhaust pipe of the lower economizer ; Fig. 1 (d) is the schematic diagram of the top view of the overall structure of the partial heating surface of the supercritical carbon dioxide circulating fluidized bed boiler;

Fig. 2 is a schematic diagram of the size of the furnace and the main heating surface of the present invention;

Fig. 3 is a schematic diagram of a Brayton cycle power generation system including a supercritical carbon dioxide circulating fluidized bed boiler.

The symbols in the drawings include: 1—supercritical carbon dioxide gas tank, 2—gas storage station, 3—supercritical carbon dioxide cold wall, 4—panel heater in the furnace, 4-a—outside panel Heater, 4-b—inner panel heater, 5—panel high temperature reheater, 6—high temperature adiabatic cyclone separator, 6-a—outer separator, 6-b—inner separator, 7—ash control valve, 8—external upper economizer, 9—low temperature reheater, 10—lower economizer, 11—air preheater, 12—high pressure turbine, 13— —low pressure turbine, 14—generator, 15—high temperature regenerator, 16—low temperature regenerator; A—reheater outlet working fluid, B—panel heater outlet working fluid, C— —Exit working fluid of superior external economizer, D——exit working fluid of high temperature regenerator, E——export working fluid of high pressure turbine, F——export working fluid of low temperature regenerator, G——exit working fluid of low pressure turbine Gas, H—the exhaust gas flows out after the low-temperature regenerator releases heat, I—the exhaust gas at the outlet of the low-temperature regenerator flows into the low-temperature regenerator as a circulating working fluid after being cooled and compressed, J——cold air inlet, K— - primary wind, L - secondary wind.

Detailed ways

Referring to Figure 1(a), the supercritical carbon dioxide circulating fluidized bed coal-fired boiler includes a supercritical carbon dioxide gas tank 1, a gas storage station 2, a wall-attached membrane supercritical carbon dioxide cold wall 3 in the furnace, a panel heater 4, and a panel heater. Type high-temperature reheater 5, high-temperature adiabatic cyclone separator 6, ash control valve 7, external upper-level economizer 8, low-temperature reheater 9 arranged in sequence along the flue gas flow direction in the tail flue, lower-level economizer 10 and Air Preheater 11. The gas storage station 2, the supercritical carbon dioxide cold wall 3, and the panel heater 4 in the furnace are all in communication with the supercritical carbon dioxide gas tank 1. Among them, the gas storage station 2 and the supercritical carbon dioxide gas tank 1 are bidirectionally connected, and the flow direction of the working fluid between the gas storage station 2 and the supercritical carbon dioxide gas tank 1 depends on the operating load of the boiler. When the load increases, the working medium is transferred from the gas storage The station 2 flows to the supercritical carbon dioxide gas tank 1. When the load drops, part of the working fluid in the supercritical carbon dioxide gas tank 1 flows into the gas storage station 2. The outlet of the cold wall 3 is connected to the inlet of the supercritical carbon dioxide gas tank 1, the inlet of the panel heater 4 is connected to the outlet of the supercritical carbon dioxide gas tank 1, and the heating medium at the outlet of the cold wall 3 flows into the panel heater 4 for further heating through the gas tank. The outlet of the low-temperature reheater 9 is connected to the inlet of the screen-type high-temperature reheater 5, and the outlet of the lower-level economizer 10 is connected to the inlet of the external upper-level economizer 8.

The outlet of the air preheater 11 is connected to the air distribution plate at the bottom of the furnace and the upper part of the dense phase area; the supercritical carbon dioxide cold wall 3, the panel heater 4 and the panel reheater 5 are arranged in the furnace, the separator 6, the ash control valve 7 and the external upper-level economizer 8 are arranged in sequence along the ash flow direction at the furnace outlet. The outlet of panel heater 4 and the inlet of low-temperature reheater 9 are respectively connected with high-pressure turbine 12 , and the outlet of panel-type high-temperature reheater 5 is connected with low-pressure turbine 13 . Thus, with the high-pressure turbine 12 as the separation point, the way the working fluid flows and is heated in the boiler can be divided into a first heating section and a second heating section. The first heating section includes a supercritical carbon dioxide cold wall 3, a supercritical carbon dioxide gas tank 1 and a panel heater 4, which are connected in sequence along the flow direction of the working medium (lower economizer 10, external upper economizer 8), and the second The heating section includes a low-temperature reheater 9 and a panel-type high-temperature reheater 5 connected in sequence along the flow direction of the working fluid.

Only the cold wall 3, the panel heater 4 and the panel reheater 5 are arranged on the heating surface in the furnace. The walls are staggered. As shown in Figure 1 (d), the panel heater 4 is made up of the first panel heater 4-a and the second panel heater 4-b connected in parallel, the first panel heater 4-a and the second panel heater The panel heater 4-b has the same size and structure.

The external upper-level economizer 8 is set in the feeder section between the outlet of the high-temperature adiabatic cyclone separator 6 and the furnace; 6-a and the second high-temperature adiabatic cyclone separator 6-b, the lower part of the first high-temperature adiabatic cyclone separator 6-a is provided with an external heating surface, and the lower part of the second high-temperature adiabatic cyclone separator 6-b is not arranged for heating noodle.

As shown in Figure 1(b) and Figure 1(c), the lower-level economizer 10 includes multiple rows of horizontally arranged pipe rows arranged in sequence from top to bottom, and each row pipe group includes multiple rows of pipe rows arranged in parallel , each row of pipes includes 4 vertically arranged pipes. The number of rows of pipes in the row of pipes is one more than that of the even-numbered rows of pipes, and the rows of pipes between adjacent rows of pipes are staggered. The outer diameter d of a single tube is 42mm, the horizontal spacing S1 between tube bundles is _75.6mm , and the longitudinal spacing S2 is _84mm .

As shown in Figure 2, the width of the furnace is D ₁ =11.9m, and the bottom width of the dense phase zone is D ₂ =7.1m. The vertical height L ₁ of the cold wall 3 of the front wall is 39.6m, and the height L ₁ +L ₂ of the rear wall is 42.4m. The height of the first panel heater 4-a and the second panel heater 4-b are H ₂ =9.8m in the furnace, and the length is H ₁ =4m, and the first panel heater 4-a and The second panel heater 4-b panel number is 13. The length of the panel-type high-temperature reheater 5 in the furnace width direction is H ₄ =4m, and the height in the furnace height direction is H ₃ =5.5m, and the number of panels of the panel-type high-temperature reheater 5 is 49. Tail flue width D ₃ =7.8m, low-temperature reheater 9 single-row tube length (pipe length in the width direction of the tail flue) H ₇ =5.9m, heating surface height (height along the extension direction of the tail flue) H ₈ = 6.6m, the height of the heating surface of the air preheater 11 (the height of the heating surface along the extension direction of the tail flue) H ₁₀ = 13.5m, the height of the heating surface of the lower economizer 10 (the height of the heating surface along the extension direction of the tail flue ) H ₉ =8.5m, the flow rate of the working fluid in the tubes of the external upper economizer 8 and the lower economizer 10 is equal, the width of the heating surface of the external upper economizer 8 is H ₅ =9.36m, and the height H ₆ =5.1m.

The circulation process of the supercritical carbon dioxide circulating fluidized bed boiler working medium in the Brayton cycle power generation system is shown in Figure 3. The circulating working fluid (supercritical carbon dioxide) first absorbs the heat from the low-pressure turbine 13 exhaust gas in the low-temperature regenerator 16, and then diverts part of the working fluid into the lower economizer 10, and the remaining working fluid continues in the high-temperature regenerator 15. Absorb the exhaust gas heat of the low-pressure turbine 13. The diverted working medium flows into the external upper economizer 8 after absorbing part of the tail flue gas heat in the lower economizer 10 . The ash content control valve 7 controls the amount of high-temperature ash entering the external upper-stage economizer 8 from the first high-temperature adiabatic cyclone separator 6-a, and the high-temperature ash further heats the diverted working fluid so that its temperature reaches the temperature at which the remaining working fluid leaves the high-temperature regenerator 15 , about 525°C. After the two streams of working fluid from the high-temperature regenerator 15 and the external upper-stage economizer 8 are mixed, they enter the cold wall 3 arranged close to the furnace wall together at the bottom of the dense-phase zone of the furnace. Then, the working fluid flows into the supercritical carbon dioxide gas tank 1 from the cold wall 3 , and at this time, if the boiler load increases, part of the working fluid in the gas storage station 2 also flows into the supercritical carbon dioxide gas tank 1 . After being uniformly mixed in the gas box 1, the working fluid flows into the panel heater 4. After the panel heater 4 heats the working fluid to 600°C, the working fluid is transported to the high-pressure turbine 12 to perform work.

After the working fluid is discharged from the high-pressure turbine 12, the temperature is about 545°C, and a reheating process is performed. This reheating process includes that the circulating working fluid first absorbs the heat of the tail flue gas in the low-temperature reheater 9, and then enters the screen-type high-temperature reheating process. Device 5 absorbs heat. When the working medium is heated in the panel reheater 5 to the same temperature as the outlet of the panel heater 4, the working medium is transported to the low-pressure turbine 13 to perform work, and drives the generator 14 to generate electricity.

Exhaust gas at the outlet of the low-pressure turbine 13 flows through the high-temperature regenerator 15 and the low-temperature regenerator 16 in turn, and releases heat as a heat source for the working fluid in the regenerator tube, which can reduce the heat supply of boiler coal combustion and increase the efficiency of the power generation system. Then the spent gas flows out of the low-temperature regenerator to be cooled and compressed to obtain a circulating working fluid, which flows into the low-temperature regenerator 16 again to participate in the next cycle, repeating the above-mentioned working medium circulation process.

The hot air entering the furnace absorbs heat from 20°C at room temperature to about 350°C in the air preheater of the final heating surface of the tail flue, and then passes the air distribution plate at the bottom of the furnace in the form of primary air and the form of secondary air respectively. It flows into the furnace from the upper part of the dense phase area, so that the fuel in the furnace can burn efficiently and stably. The high-temperature flue gas generated by combustion first transfers heat to the inner cold wall 3 of the furnace, the panel heater 4, and the panel reheater 5, and then flows to the tail flue to sequentially feed the low-temperature reheater 9, the lower economizer 10 and the air preheater. Heater 11 delivers heat. After the flue gas flows out from the air preheater 11, the temperature is significantly reduced, and the loss of exhaust gas is small.

The efficiency of the supercritical carbon dioxide circulating fluidized bed coal-fired boiler of the invention is greater than 93%.

Claims (8)

1. A supercritical carbon dioxide circulating fluidized bed coal-fired boiler is characterized in that it comprises a supercritical carbon dioxide gas tank (1), a gas storage station (2), a membrane type supercritical carbon dioxide cold wall (3), and a panel heating (4), panel high-temperature reheater (5), separator (6), ash control valve (7), external upper-level economizer (8), low-temperature reheater (9), lower-level economizer (10) and air preheater (11); Described membrane supercritical carbon dioxide cold wall (3), panel heater (4) and panel high temperature reheater (5) are arranged in the furnace, separator ( 6), the ash control valve (7) and the external upper-level economizer (8) are arranged in sequence along the ash flow direction at the furnace outlet, the low-temperature reheater (9), the lower-level economizer (10) and the air preheater (11 ) are sequentially arranged in the tail flue along the flue gas flow direction; The gas storage station (2) is in two-way communication with the supercritical carbon dioxide gas tank (1), and the inlet of the membrane supercritical carbon dioxide cold wall (3) is connected with the outlet of the external upper-level economizer (8) and the high temperature return respectively. Heater (15) outlet Unicom; There are only membrane supercritical carbon dioxide cold walls (3), panel heaters (4) and panel high-temperature reheaters (5) in the furnace, and the membrane supercritical carbon dioxide cold walls (3) are along the four walls of the furnace. The panel heater (4) and the panel high-temperature reheater (5) are respectively hung on the front and rear walls of the furnace and arranged in a staggered manner, and the panel heater (4) is arranged by the first panel heater in parallel. (4-a) and the second panel heater (4-b). 2. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, characterized in that the bottom width of the dense phase zone is D ₂ =0.55-0.65D ₁ ; the height of the cold wall arranged on the front wall of the furnace is L ₁ , the height of the cold wall of the back wall is L ₁ +L ₂ , L ₂ =0.063～0.078L ₁ ; the first panel heater (4-a) and the second panel heater (4-b) are inside the furnace The height along the furnace length extension direction is H ₂ =0.22～0.27L ₁ , the length in the furnace width direction is H ₁ =0.37～0.45H ₂ , and the first panel heater (4-a) and the second The panel heater (4-b) is located in the middle and upper part of the furnace; the height of the panel high-temperature reheater (5) in the furnace is H ₃ =0.5-0.6H ₂ , and the length is H ₄ =0.9-1.1H ₁ ; D ₁ represents the furnace width. 3. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, characterized in that, the separator (6) is a high-temperature adiabatic cyclone separator, and the external upper-level economizer (8) is set The feeder section between the separator (6) outlet and the furnace; the high-temperature adiabatic cyclone separator includes a first high-temperature adiabatic cyclone separator (6-a) symmetrically arranged according to the panel high-temperature reheater (5) and the second high-temperature adiabatic cyclone separator (6-b), the lower part of the first high-temperature adiabatic cyclone separator (6-a) is provided with an external heating surface, and the second high-temperature adiabatic cyclone separator (6-b) There is no heating surface arranged in the lower part. 4. supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, is characterized in that, in the tail flue, the tail horizontal transition flue is not provided with a heating surface, and the low-temperature reheater (9) row pipe is Serpentine tube, the tube length of the low-temperature reheater (9) in the width direction of the tail flue is smaller than the width of the tail flue; the outlet of the air preheater (11) is connected to the air distribution plate at the bottom of the furnace and the upper part of the dense phase zone . 5. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, characterized in that the tube length of the low-temperature reheater (9) in the width direction of the tail flue is H ₇ =0.7～0.85D _3. The height of the low-temperature reheater along the extension direction of the tail flue is H ₈ =0.76～0.93D ₃ ; the external upper-stage economizer (8) is located at the lower part of the first high-temperature adiabatic cyclone separator and is parallel to the feeder, and the external The width of the heating surface of the upper economizer H ₅ =1.08～1.3H ₇ , the height of the heating surface of the external upper economizer H ₆ =0.54～0.66H ₈ ; D ₃ represents the width of the tail flue. 6. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, characterized in that the row pipes in the lower economizer are arranged in a staggered arrangement; the height of the lower economizer is H ₉ =0.99～1.21D ₃ ; The height of the heating surface of the air preheater along the extension direction of the tail flue is H ₁₀ =1.6-1.91D ₃ ; D ₃ represents the width of the tail flue. 7. The supercritical carbon dioxide circulating fluidized bed coal-fired boiler according to claim 1, characterized in that, the lower-level economizer (10), the external upper-level economizer (8), the membrane type supercritical carbon dioxide cooler The wall (3), the supercritical carbon dioxide gas tank (1) and the panel heater (4) are sequentially connected along the flow direction of the working fluid, and the low-temperature reheater (9) and the panel-type high-temperature reheater (5) are connected along the working fluid direction. The mass flow direction is sequentially connected, the outlet of the panel heater (4) and the inlet of the low-temperature reheater (9) are connected to the high-pressure turbine (12) respectively, and the outlet of the panel high-temperature reheater (5) is connected to the The low-pressure turbine (13) is connected. 8. A supercritical carbon dioxide power generation system, characterized in that the supercritical carbon dioxide power generation system comprises the supercritical carbon dioxide circulating fluidized bed coal-fired boiler described in any one of claims 1 to 7, and the supercritical carbon dioxide Circulating fluidized bed coal-fired boiler drives power generation.