Negative carbon combined heat and power system integrating biomass direct combustion and gasification and operation method

Abstract

The present invention discloses a negative carbon combined heat and power system integrating biomass direct combustion and gasification and an operation method. The system includes biomass direct combustion, biomass gasification and flue gas treatment parts. The installed capacity is reasonably equipped, and the complementary integration of biomass multi-disposal and combined heat and power is realized through energy cascade utilization and waste heat deep recovery. The biomass fuel is burned in a direct-fired boiler or gasified in a gasifier, and the feed water absorbs heat and evaporates in the boiler and enters the steam turbine to expand and do work; the gasified synthesis gas first drives the solid oxide fuel cell to generate electricity, and then enters the gas turbine to expand and do work after supplementary combustion. The exhaust gas of the gas turbine is divided into two paths, one of which heats the high-pressure feed water and the low-pressure feed water successively; the other path heats the hot network water and is used to preheat the compressed air. The flue gas is passed through a carbon capture device to remove carbon dioxide. The present invention promotes the resource utilization of agricultural and forestry waste organic matter by reasonably coupling biomass direct combustion, biomass gasification and flue gas treatment, realizes negative carbon emissions in the whole process, and has significant environmental protection performance.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power generation, and in particular to a negative carbon combined heat and power system and an operation method that integrates direct combustion and gasification of biomass, and specifically to an energy system that integrates direct combustion, gasification and carbon capture in areas rich in biomass resources to supply heat and power. Background Art

[0002] At present, there is still a lot of crude use of fossil fuels in rural areas, with low energy efficiency and high emission levels.

[0003] In addition, the development of large-scale agriculture has also brought about the problem of waste biomass disposal, and the open-air burning of crop straw is still common. The burning of farmland is not only a huge waste of energy, but also causes the aggravation of smog weather, and the harmful substances emitted pose a threat to the health of humans and other organisms. In fact, compared with the intermittent and volatile use of solar energy and wind energy due to weather changes, biomass is a renewable carbon-containing fuel with high energy density, stability and reliability.

[0004] The diversified development of renewable energy has brought new opportunities for the utilization of biomass. It can be combined with the current characteristics of local biomass and develop and utilize biomass resources according to local conditions. During the growth process, crops absorb and fix carbon dioxide in the air through photosynthesis. If carbon capture technology is coupled in the comprehensive utilization of biomass to absorb carbon dioxide in the exhaust, it is possible to achieve zero carbon dioxide emissions while avoiding the cost of fossil energy utilization and biomass treatment, protect the local ecological environment, and play a positive role in the 1.5℃ temperature rise target in the Paris Agreement. In this way, in the whole process of crop growth, utilization, and tail gas treatment, there is only carbon dioxide intake, but no carbon dioxide emission. Therefore, negative carbon cogeneration is achieved in the whole process, which can not only improve the reliability and stability of the energy utilization system in rural areas, but also promote the sustainable development of energy structure and environmental protection. Due to its huge utilization potential, promoting the comprehensive utilization of biomass energy is an effective way to develop new energy systems and resource-based treatment of agricultural waste in rural areas. Summary of the invention

[0005] Aiming at the problem of efficient utilization of biomass energy in areas rich in agricultural and forestry biomass resources, the present invention proposes a negative carbon combined heat and power system and operation method integrating biomass direct combustion and gasification. The system includes three parts: biomass direct combustion, flue gas treatment, and biomass gasification. The complementary integration of combined heat and power is achieved through the deep recovery of waste heat and the cascade utilization of energy. Organic biomass is burned in a biomass direct-fired boiler or gasified in a biomass gasifier. After the feed water absorbs heat and evaporates in the boiler, it enters the steam turbine to expand and do work to realize the Rankine cycle; after the gasification synthesis gas is purified, it first drives the solid oxide fuel cell to generate electricity, and then enters the gas turbine to expand and do work after supplementary combustion. The exhaust gas of the gas turbine is divided into two paths. One path successively heats the high-pressure feed water and the low-pressure feed water in the #2 feed water heat exchanger and the #1 feed water heat exchanger to the inlet feed water demand temperature of the biomass direct-fired boiler and the deaerator respectively; the other path heats the hot network water through the waste heat boiler and then enters the air preheater to heat the compressed air. The flue gas of the gas turbine merges with the flue gas generated by the biomass direct-fired boiler and enters the carbon capture device for carbon dioxide removal. The present invention realizes the cascade utilization of energy and the efficient recovery of flue gas waste heat by rationally coupling biomass direct combustion, biomass gasification and flue gas treatment equipment, promotes the resource disposal and local consumption of agricultural and forestry waste organic matter, meets the thermal power needs of local residents, and greatly improves the overall economic efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A negative carbon combined heat and power system integrating biomass direct combustion and gasification, the system comprising a biomass direct combustion part, a flue gas treatment part and a biomass gasification part; the biomass direct combustion part comprises a biomass direct combustion boiler, a steam turbine, a #1 generator, a condenser, a condensate pump, a #1 valve, a #3 low-pressure heater, a #2 low-pressure heater, a #1 low-pressure heater, a deaerator, a feed water pump, a #2 valve, a #2 high-pressure heater, a #1 high-pressure heater, a #1 feed water heat exchanger and a #2 feed water heat exchanger; the flue gas treatment part comprises a dust collector, a desulfurization and denitrification device, a mixer, a carbon capture device, a #6 valve and a chimney; the biomass gasification part comprises a biomass gasifier, a gas purification device, a reformer, a solid oxide fuel cell, a converter, a combustion chamber, a gas turbine, a #2 generator, an electric motor, a compressor, an air preheater, a waste heat boiler, a #3 valve, a #4 valve and a #5 valve;

[0008] In the biomass direct combustion part, the steam outlet of the biomass direct combustion boiler is connected to the steam inlet of the steam turbine, the steam turbine is coaxially connected to the #1 generator, the exhaust outlet of the steam turbine is connected to the condenser inlet, and the outlet condensate of the condenser is divided into two paths after being pressurized by the condensate pump. One path passes through the #3 low-pressure heater, the #2 low-pressure heater and the #1 low-pressure heater in sequence, and the other path passes through the #1 valve and the #1 feed water heat exchanger in sequence. The two paths merge and enter the deaerator inlet; the outlet feed water of the deaerator is divided into two paths after being pressurized by the feed water pump, one path One route passes through #2 high-pressure heater and #1 high-pressure heater in sequence, and the other route passes through #2 valve and #2 feedwater heat exchanger in sequence. After the two routes merge, they enter the biomass direct-fired boiler; #1 high-pressure heater, #2 high-pressure heater, deaerator, #1 low-pressure heater, #2 low-pressure heater and #3 low-pressure heater use steam from the steam turbine as heat source in sequence; the drain in #1 high-pressure heater and #2 high-pressure heater flows by gravity to the deaerator step by step; the drain in #1 low-pressure heater, #2 low-pressure heater and #3 low-pressure heater flows by gravity to the condenser step by step;

[0009] In the flue gas treatment part, the flue gas of the biomass direct-fired boiler passes through the dust collector and the desulfurization and denitrification device in sequence, and enters the mixer together with the flue gas from the #1 feedwater heat exchanger and the air preheater. The outlet of the mixer is connected to the flue gas inlet of the carbon capture device, and the flue gas outlet of the carbon capture device is connected to the chimney; the steam inlet of the carbon capture device is connected to the #6 valve, and the steam entering the #6 valve and the steam entering the #2 low-pressure heater are from the same steam source, and the drain of the carbon capture device merges with the outlet drain of the #3 low-pressure heater and flows to the condenser;

[0010] In the biomass gasification part, the biomass fuel is gasified in the biomass gasifier, and the generated synthesis gas is processed by the gas purification device and the reformer in turn and then enters the anode of the solid oxide fuel cell. The cathode inlet of the solid oxide fuel cell is connected to the #5 valve, and the anode outlet synthesis gas of the solid oxide fuel cell is divided into two paths, one path enters the reformer through the #4 valve, and the other path is connected to the combustion chamber. The cathode outlet of the solid oxide fuel cell is connected to the combustion chamber, and the outlet flue gas of the combustion chamber enters the gas turbine to expand and do work, and generates electricity through the #2 generator; the electric motor drives the compressor to compress the air, and the compressor outlet is connected to the air preheater. The heat source inlet of the air preheater is connected to the flue gas outlet of the waste heat boiler, and the flue gas inlet of the waste heat boiler is connected to the exhaust outlet of the gas turbine; the converter is connected to the solid oxide fuel cell to convert the direct current generated by the solid oxide fuel cell into alternating current; the hot network water enters the waste heat boiler to absorb heat and heat up, and then goes to the heat user for heating.

[0011] Specifically, the flue gas discharged from the gas turbine outlet is divided into two paths. One path goes to the #2 feed water heat exchanger through the #3 valve to heat the high-pressure feed water at the #2 valve outlet to the inlet feed water requirement temperature of the biomass direct-fired boiler, and the cooled flue gas goes to the #1 feed water heat exchanger to heat the low-pressure feed water at the #1 valve outlet to the inlet feed water requirement temperature of the deaerator; the other path goes to the waste heat boiler to heat the hot network water, and after cooling, it goes to the air preheater to heat the compressed air from the compressor; the two flue gases from the gas turbine merge with the flue gas generated by the biomass direct-fired boiler at the outlet of the desulfurization and denitrification device, and enter the carbon capture device after passing through the mixer to remove carbon dioxide.

[0012] Specifically, the inlet heat source of the #2 feedwater heat exchanger is the flue gas exhausted by the gas turbine, which releases heat and flows to the #1 feedwater heat exchanger; the inlet cold source of the #2 feedwater heat exchanger is a part of the feedwater pressurized by the feedwater pump, and the feedwater after absorbing heat flows to the feedwater inlet of the biomass direct-fired boiler.

[0013] Specifically, the inlet heat source of the #1 feed water heat exchanger is the flue gas from the #2 feed water heat exchanger, which is passed to the mixer after releasing heat in the #1 feed water heat exchanger; the inlet cold source of the #1 feed water heat exchanger is a part of the condensate boosted by the condensate pump, which is passed to the deaerator after absorbing heat.

[0014] Specifically, the inlet heat source of the air preheater is the flue gas of the gas turbine that has released heat in the waste heat boiler, and the outlet flue gas enters the mixer; the inlet cold source of the air preheater is the air compressed by the compressor, which is divided into two paths after absorbing heat, one path goes to the cathode of the solid oxide fuel cell through the #5 valve, and the other path enters the biomass gasifier.

[0015] Specifically, the #1 valve is used to adjust the feed water flow entering the #1 feed water heat exchanger; the #2 valve is used to adjust the feed water flow entering the #2 feed water heat exchanger; the #3 valve is used to adjust the flue gas flow entering the #2 feed water heat exchanger; the #4 valve is used to adjust the synthesis gas flow entering the reformer; the #5 valve is used to adjust the air flow entering the solid oxide fuel cell; and the #6 valve is used to adjust the steam flow entering the carbon capture device.

[0016] Specifically, the fuel required for the biomass direct-fired boiler and the biomass gasifier is agricultural and forestry biomass, mainly including straw, rice husk and wood.

[0017] The present invention has the following advantages and effects:

[0018] 1) Through the reasonable coupling of different forms of biomass utilization, the share of renewable energy is increased, which is in line with local resource endowment and load demand, so that energy utilization in areas rich in agricultural and forestry waste resources can be localized, adapted to local conditions, green and efficient;

[0019] 2) The diversified resource disposal of agricultural and forestry biomass avoids environmental pollution caused by open-air burning, while achieving the benefits of power generation and heating;

[0020] 3) After the biomass gasification synthesis gas is purified, it first drives the solid oxide fuel cell to generate electricity through electrochemical reaction, with high energy conversion efficiency. The flue gas at the fuel cell outlet is supplemented by combustion and then enters the gas turbine to expand and do work, thus realizing the cascade utilization of energy;

[0021] 4) The high-temperature exhaust gas of the gas turbine is divided into two paths. One path is used to heat the high-pressure feed water and low-pressure feed water of the biomass direct-fired unit successively, and the other path is used to heat the compressed air after heating. Through the distribution of energy grade, the exhaust waste heat is deeply recovered;

[0022] 5) Using the waste heat from gas turbine exhaust to assist in heating the feed water of the biomass direct-fired unit saves the heat recovery steam extraction of the biomass unit; using the exhaust from gas turbine to heat the hot network water replaces the heating steam extraction used in the conventional solution, which increases the power generation of the biomass direct-fired unit;

[0023] 6) The flue gas from the gas turbine merges with the flue gas generated by the biomass direct-fired boiler and enters the carbon capture device for carbon dioxide removal, achieving negative carbon emissions in the entire process of biomass utilization, which plays a positive role in environmental protection;

[0024] 7) The system can effectively reduce the infrastructure construction cost and energy loss of long-distance power transmission and heating to concentrated agricultural areas, and the supporting facilities for system operation are relatively simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a negative carbon combined heat and power system integrating biomass direct combustion and gasification.

[0026] In the figure: I-biomass direct combustion part; II-flue gas treatment part; III-biomass gasification part; 1-biomass direct combustion boiler; 2-steam turbine; 3-#1 generator; 4-condenser; 5-condensate pump; 6-#1 valve; 7-#3 low pressure heater; 8-#2 low pressure heater; 9-#1 low pressure heater; 10-deaerator; 11-feed water pump; 12-#2 valve; 13-#2 high pressure heater; 14-#1 high pressure heater; 15-#1 feed water heat exchanger; 16-#2 feed water heat exchanger device; 17-dust collector; 18-desulfurization and denitrification device; 19-mixer; 20-carbon capture device; 21-chimney; 22-biomass gasifier; 23-gas purification device; 24-reformer; 25-solid oxide fuel cell; 26-converter; 27-combustion chamber; 28-gas turbine; 29-#2 generator; 30-electric motor; 31-compressor; 32-air preheater; 33-waste heat boiler; 34-#3 valve; 35-#4 valve; 36-#5 valve; 37-#6 valve. DETAILED DESCRIPTION

[0027] The present invention proposes a negative carbon combined heat and power system and an operation method integrating direct combustion and gasification of biomass. The specific process is described below with reference to the accompanying drawings and examples.

[0028] like Figure 1 The negative carbon combined heat and power system integrating biomass direct combustion and gasification shown in the figure includes a biomass direct combustion part I, a flue gas treatment part II and a biomass gasification part III.

[0029] Biomass fuels such as crop straw are burned in the biomass direct-fired boiler 1, and the feed water absorbs heat and evaporates to form superheated steam (temperature is about 500°C). The superheated steam at the outlet enters the steam turbine 2 to drive the impeller to expand and do work, thereby driving the #1 generator 3 to generate electricity. The exhaust steam of the steam turbine 2 (temperature is about 35°C) is condensed in the condenser 4, and the condensate is pressurized by the condensate pump 5 and divided into two paths. One path absorbs the heat of the extraction steam in the #3 low-pressure heater 7, the #2 low-pressure heater 8 and the #1 low-pressure heater 9 in turn and heats up, and the other path is heated by the flue gas of the gas turbine 28 in the #1 feed water heat exchanger 15. The two paths are heated to the same water temperature of 135°C and enter the deaerator 10 together after merging. The outlet feed water of the deaerator 10 is pressurized by the feed water pump 11 and divided into two paths. One path absorbs the heat of the extraction steam in the #2 high pressure heater 13 and the #1 high pressure heater 14 in turn and is heated. The other path is heated by the flue gas of the gas turbine 28 in the #2 feed water heat exchanger 16. The two paths are heated to the same water temperature of 220°C and enter the biomass direct-fired boiler 1 together after merging. The #1 high pressure heater 14, the #2 high pressure heater 13, the deaerator 10, the #1 low pressure heater 9, the #2 low pressure heater 8 and the #3 low pressure heater 7 all extract steam from the steam turbine 2 as a heat source, and the pressure and temperature of the extraction steam are reduced sequentially.

[0030] At the same time, biomass fuels such as crop straw are gasified in the biomass gasifier 22, and the generated synthesis gas is purified by the gas purification device 23 and reformed in the reformer 24, and then enters the anode of the solid oxide fuel cell 25. The motor 30 drives the compressor 31 to compress the air to a certain pressure, and then enters the air preheater 32 to be heated by the flue gas of the gas turbine 28, and then sent to the cathode of the solid oxide fuel cell 25. Electrochemical reactions occur in the solid oxide fuel cell 25 to generate direct current, which is converted into alternating current by the converter 26. The unreacted synthesis gas (temperature of about 750°C) at the anode outlet is divided into two paths, one part goes to the reformer 24 to assist in the reforming of the synthesis gas, the mainstream and the cathode tail gas enter the combustion chamber 27 for supplementary combustion, and the generated high-temperature and high-pressure gas enters the gas turbine 28 to drive the impeller to expand and do work, driving the #2 generator 29 to generate electricity. The flue gas (with a temperature of about 450°C) exhausted by the gas turbine 28 is divided into two paths. One path successively heats the high-pressure feed water and the low-pressure feed water in the #2 feed water heat exchanger 16 and the #1 feed water heat exchanger 15 to the required inlet feed water temperature of the biomass direct-fired boiler 1 and the deaerator 10 respectively; the other path heats the hot network water to the required heating water temperature in the waste heat boiler 33 and then enters the air preheater 32 to heat the compressed air, thereby realizing the deep recovery and utilization of the waste heat of the flue gas.

[0031] The flue gas of the biomass direct-fired boiler 1 is dedusted and desulfurized and denitrated in the dust collector 17 and the desulfurization and denitration device 18 respectively, and then enters the mixer 19 together with the flue gas of the two-way gas turbine 28, and is discharged through the chimney after being decarbonized in the carbon capture device 20. The driving heat source of the carbon capture device 20 is the extraction steam from the steam turbine 2 (temperature is about 125°C), which is the same steam source as the steam entering the #2 low-pressure heater 8, and the drain merges with the outlet drain of the #3 low-pressure heater 7 and flows into the condenser 4 together.

[0032] Specifically, in the #2 feedwater heat exchanger 16, the flue gas discharged from the gas turbine 28 releases heat to heat a portion of the feedwater pressurized by the feedwater pump 11; in the #1 feedwater heat exchanger 15, the flue gas that has been released and cooled in the #2 feedwater heat exchanger 16 continues to release heat to heat a portion of the condensate pressurized by the condensate pump 5; in the air preheater 32, the flue gas of the gas turbine 28 that has heated the hot network water in the waste heat boiler 33 releases heat to heat the air compressed by the compressor 31. All three are preferably arranged as countercurrent heat exchange.

[0033] Specifically, the #1 valve 6 is used to distribute low-pressure feed water and adjust the feed water flow entering the #1 feed water heat exchanger 15; the #2 valve 12 is used to distribute high-pressure feed water and adjust the feed water flow entering the #2 feed water heat exchanger 16; the #3 valve 34 is used to distribute the flue gas of the gas turbine 28 and adjust the flue gas flow entering the #2 feed water heat exchanger 16; the #4 valve 35 is used to distribute the anode outlet synthesis gas of the solid oxide fuel cell 25 and adjust the synthesis gas flow entering the reformer 24; the #5 valve 36 is used to distribute the preheated compressed air and adjust the air flow entering the cathode of the solid oxide fuel cell 25; the #6 valve 37 is used to distribute the extraction steam at this temperature and adjust the steam flow entering the carbon capture device 20. The power generation of the #1 generator 3, the #2 generator 29 and the solid oxide fuel cell 25 can meet the local electricity load demand. The heat supply can be adjusted by changing the flow of the hot water network and the flue gas of the gas turbine 28.

[0034] The present invention focuses on the energy system in areas rich in biomass resources, makes diversified complementary use of biomass, couples carbon capture devices, and transforms agricultural and forestry waste biomass into resources and treats it harmlessly, promotes power generation and heat supply while achieving negative carbon dioxide emissions throughout the entire process, meets residents' energy needs, and promotes energy conservation, emission reduction, and environmental protection.

[0035] In addition, it should be noted that the shapes and names of the parts of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A negative carbon combined heat and power system integrating biomass direct combustion and gasification, the system comprising a biomass direct combustion part (I), a flue gas treatment part (II) and a biomass gasification part (III); the biomass direct combustion part (I) comprises a biomass direct combustion boiler (1), a steam turbine (2), a #1 generator (3), a condenser (4), a condensate pump (5), a #1 valve (6), a #3 low pressure heater (7), a #2 low pressure heater (8), a #1 low pressure heater (9), a deaerator (10), a feed water pump (11), a #2 valve (12), a #2 high pressure heater (13), a #1 high pressure heater (14), a #1 feed water heat exchanger (15) and a #2 feed water heat exchanger ( 16); the flue gas treatment part (II) includes a dust collector (17), a desulfurization and denitrification device (18), a mixer (19), a carbon capture device (20), a #6 valve (37) and a chimney (21); the biomass gasification part (III) includes a biomass gasifier (22), a gas purification device (23), a reformer (24), a solid oxide fuel cell (25), a converter (26), a combustion chamber (27), a gas turbine (28), a #2 generator (29), an electric motor (30), a compressor (31), an air preheater (32), a waste heat boiler (33), a #3 valve (34), a #4 valve (35) and a #5 valve (36); In the biomass direct combustion part (I), the steam outlet of the biomass direct combustion boiler (1) is connected to the steam inlet of the steam turbine (2), the steam turbine (2) is coaxially connected to the #1 generator (3), the exhaust outlet of the steam turbine (2) is connected to the inlet of the condenser (4), the outlet condensate of the condenser (4) is pressurized by the condensate pump (5) and is divided into two paths, one path passes through the #3 low-pressure heater (7), the #2 low-pressure heater (8) and the #1 low-pressure heater (9) in sequence, and the other path passes through the #1 valve (6) and the #1 feed water heat exchanger (15) in sequence, and the two paths merge and enter the inlet of the deaerator (10); the outlet feed water of the deaerator (10) is pressurized by the feed water pump (11) and is divided into two paths, one path passes through the #2 The high-pressure heater (13) and the #1 high-pressure heater (14), and the other route passes through the #2 valve (12) and the #2 feedwater heat exchanger (16) in sequence, and the two routes merge and enter the biomass direct-fired boiler (1); the #1 high-pressure heater (14), the #2 high-pressure heater (13), the deaerator (10), the #1 low-pressure heater (9), the #2 low-pressure heater (8) and the #3 low-pressure heater (7) sequentially use the steam of the steam turbine (2) as a heat source; the drain in the #1 high-pressure heater (14) and the #2 high-pressure heater (13) flows step by step to the deaerator (10); the drain in the #1 low-pressure heater (9), the #2 low-pressure heater (8) and the #3 low-pressure heater (7) flows step by step to the condenser (4); In the flue gas treatment part (II), the flue gas of the biomass direct-fired boiler (1) passes through the dust collector (17) and the desulfurization and denitrification device (18) in sequence, and enters the mixer (19) together with the flue gas from the #1 feed water heat exchanger (15) and the air preheater (32). The outlet of the mixer (19) is connected to the flue gas inlet of the carbon capture device (20), and the flue gas outlet of the carbon capture device (20) is connected to the chimney (21); the steam inlet of the carbon capture device (20) is connected to the #6 valve (37), and the steam entering the #6 valve (37) and the steam entering the #2 low-pressure heater (8) are from the same steam source. The drain of the carbon capture device (20) merges with the outlet drain of the #3 low-pressure heater (7) and flows to the condenser (4); In the biomass gasification part (III), the biomass fuel is gasified in the biomass gasifier (22), and the generated synthesis gas is processed by the gas purification device (23) and the reformer (24) in sequence before entering the anode of the solid oxide fuel cell (25). The cathode inlet of the solid oxide fuel cell (25) is connected to the #5 valve (36). The anode outlet synthesis gas of the solid oxide fuel cell (25) is divided into two paths, one path enters the reformer (24) through the #4 valve (35), and the other path is connected to the combustion chamber (27). The cathode outlet of the solid oxide fuel cell (25) is connected to the combustion chamber (27), and the outlet smoke of the combustion chamber (27) is connected to the combustion chamber (27). The gas enters the gas turbine (28) to expand and perform work, and then generates electricity through the #2 generator (29); the motor (30) drives the compressor (31) to compress the air, and the outlet of the compressor (31) is connected to the air preheater (32), the heat source inlet of the air preheater (32) is connected to the flue gas outlet of the waste heat boiler (33), and the flue gas inlet of the waste heat boiler (33) is connected to the exhaust outlet of the gas turbine (28); the converter (26) is connected to the solid oxide fuel cell (25) to convert the direct current generated by the solid oxide fuel cell (25) into alternating current; the hot network water enters the waste heat boiler (33), absorbs heat and rises in temperature, and then goes to the heat user to provide heat.

2. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The flue gas discharged from the outlet of the gas turbine (28) is divided into two paths. One path passes through the #3 valve (34) to the #2 feed water heat exchanger (16) to heat the high-pressure feed water at the outlet of the #2 valve (12) to the required inlet feed water temperature of the biomass direct-fired boiler (1). The cooled flue gas passes through the #1 feed water heat exchanger (15) to heat the low-pressure feed water at the outlet of the #1 valve (6) to the required inlet feed water temperature of the deaerator (10); the other path passes through the waste heat boiler (33) to heat the hot network water, and after cooling, passes through the air preheater (32) to heat the compressed air from the compressor (31); The two flue gases from the gas turbine (28) are combined with the flue gas generated by the biomass direct-fired boiler (1) at the outlet of the desulfurization and denitrification device (18), and then enter the carbon capture device (20) for carbon dioxide removal after passing through the mixer (19).

3. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The inlet heat source of the #2 feed water heat exchanger (16) is the flue gas exhausted by the gas turbine (28), and the flue gas releases heat and flows to the #1 feed water heat exchanger (15); the inlet cold source of the #2 feed water heat exchanger (16) is a part of the feed water pressurized by the feed water pump (11), and the feed water after absorbing heat flows to the feed water inlet of the biomass direct-fired boiler (1).

4. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The inlet heat source of the #1 feed water heat exchanger (15) is the flue gas from the #2 feed water heat exchanger (16), and the flue gas is passed to the mixer (19) after releasing heat in the #1 feed water heat exchanger (15); the inlet cold source of the #1 feed water heat exchanger (15) is a part of the condensate pressurized by the condensate pump (5), and is passed to the deaerator (10) after absorbing heat.

5. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The inlet heat source of the air preheater (32) is the flue gas of the gas turbine (28) that has released heat in the waste heat boiler (33), and the outlet flue gas enters the mixer (19); the inlet cold source of the air preheater (32) is the air compressed by the compressor (31), which is divided into two paths after absorbing heat, one path goes to the cathode of the solid oxide fuel cell (25) through the #5 valve (36), and the other path enters the biomass gasifier (22).

6. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The #1 valve (6) is used to adjust the feed water flow entering the #1 feed water heat exchanger (15); the #2 valve (12) is used to adjust the feed water flow entering the #2 feed water heat exchanger (16); the #3 valve (34) is used to adjust the flue gas flow entering the #2 feed water heat exchanger (16); the #4 valve (35) is used to adjust the synthesis gas flow entering the reformer (24); the #5 valve (36) is used to adjust the air flow entering the solid oxide fuel cell (25); and the #6 valve (37) is used to adjust the steam flow entering the carbon capture device (20).

7. The negative carbon combined heat and power system integrating biomass direct combustion and gasification according to claim 1 is characterized in that: The fuel required for the biomass direct-fired boiler (1) and the biomass gasifier (22) is agricultural and forestry biomass, which includes straw, rice husk and wood.

8. The method for operating the negative carbon combined heat and power system integrating biomass direct combustion and gasification according to any one of claims 1 to 7, characterized in that: Biomass fuel is burned in a biomass direct-fired boiler (1), and feed water absorbs heat and evaporates to form superheated steam. The superheated steam at the outlet enters a steam turbine (2) to drive the impeller to expand and do work, thereby driving the #1 generator (3) to generate electricity. The exhaust steam of the steam turbine (2) is condensed in a condenser (4), and the condensate is pressurized by a condensate pump (5) and then divided into two paths. One path absorbs the heat of the extraction steam in the #3 low-pressure heater (7), the #2 low-pressure heater (8) and the #1 low-pressure heater (9) in turn to increase the temperature, and the other path is heated by the flue gas of the gas turbine (28) in the #1 feed water heat exchanger (15). The two paths are heated to the same water temperature and then merged and enter the deaerator (10) together; Deaerator The outlet feed water of (10) is pressurized by the feed water pump (11) and then divided into two paths. One path absorbs the heat of the extraction steam in the #2 high-pressure heater (13) and the #1 high-pressure heater (14) in turn to be heated, and the other path is heated by the flue gas of the gas turbine (28) in the #2 feed water heat exchanger (16). The two paths are heated to the same water temperature and then merged to enter the biomass direct-fired boiler (1) together; the #1 high-pressure heater (14), the #2 high-pressure heater (13), the deaerator (10), the #1 low-pressure heater (9), the #2 low-pressure heater (8) and the #3 low-pressure heater (7) all extract steam from the steam turbine (2) as a heat source, and the pressure and temperature of the extraction steam are reduced sequentially; At the same time, the biomass fuel is gasified in the biomass gasifier (22), and the generated synthesis gas is purified by the gas purification device (23) and reformed in the reformer (24), and then enters the anode of the solid oxide fuel cell (25); the motor (30) drives the compressor (31) to compress the air, and then enters the air preheater (32) to be heated by the flue gas of the gas turbine (28), and then sent to the cathode of the solid oxide fuel cell (25); an electrochemical reaction occurs in the solid oxide fuel cell (25) to generate direct current, which is converted into alternating current by the converter (26); the synthesis gas that has not been completely reacted at the anode outlet is divided into two paths, one part of which goes to the reformer (24) Auxiliary synthesis gas reforming, the mainstream and cathode tail gas enter the combustion chamber (27) for supplementary combustion, and the generated high-temperature and high-pressure gas enters the gas turbine (28) to drive the impeller to expand and do work, thereby driving the #2 generator (29) to generate electricity; the flue gas discharged from the gas turbine (28) is divided into two paths, one path successively heats the high-pressure feed water and the low-pressure feed water in the #2 feed water heat exchanger (16) and the #1 feed water heat exchanger (15) to the required inlet feed water temperature of the biomass direct-fired boiler (1) and the deaerator (10); the other path heats the hot network water in the waste heat boiler (33) to the required water temperature for heating, and then enters the air preheater (32) to heat the compressed air, thereby realizing the deep recovery and utilization of the flue gas waste heat; The flue gas of the biomass direct-fired boiler (1) is subjected to dust removal and desulfurization and denitrification in a dust collector (17) and a desulfurization and denitrification device (18) respectively, and then enters a mixer (19) together with the flue gas of two gas turbines (28), and is decarbonized in a carbon capture device (20) before being discharged through a chimney in compliance with the emission standards; the driving heat source of the carbon capture device (20) is the extraction steam from the steam turbine (2), which is the same steam source as the steam entering the #2 low-pressure heater (8), and the drain is combined with the outlet drain of the #3 low-pressure heater (7) and flows into the condenser (4) together.

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