Coal-fired boiler system and process doped with biomass gas

Abstract

This invention discloses a coal-fired boiler system and process for co-firing biomass gas, belonging to the field of energy conservation and emission reduction technology for coal-fired boilers. Applied to the air inlet side of the main combustion zone of a coal-fired boiler, it includes a gasification device, a sampling device, and a flow control device. Biomass solid fuel and a gasifying agent generate biomass gas in the gasification device. The biomass gas is connected to the flow control device via a pipeline. The flow control device outputs the biomass gas to the perimeter air outlet of the main combustion zone for co-firing. The sampling device is installed on the pipeline between the gasification device and the flow control device to sample and detect the biomass gas. This invention's coal-fired boiler system for co-firing biomass gas ensures efficient utilization of biomass energy while precisely controlling and reducing NO pollutants without altering existing coal-fired boiler technology. x Emissions.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and emission reduction technology for coal-fired boilers, and in particular to a coal-fired boiler system and process for co-firing biomass fuel gas. Background Technology

[0002] Biomass energy is used in power generation and metallurgy as a substitute for coal. The main utilization methods include direct combustion of solid biomass fuel and co-firing with pulverized coal. A second most common method is the production of biogas using gasification technology for co-firing with pulverized coal. When directly burning solid biomass fuel or co-firing with pulverized coal, the solid biomass fuel is often ground, crushed, and dried like raw coal before being fed into the boiler for combustion and heat release. However, this direct combustion method places high demands on the boiler type because of the diversity of biomass types, their varying calorific value and degree of refinement. Boilers that directly burn biomass fuel have a strong capacity for load regulation. Although numerous examples show that the combustion of solid biomass can reduce coal consumption and NOx pollution to some extent... x While biomass produces emissions, its combustion process also causes coking, slagging, and wear in boilers, increasing maintenance costs. Furthermore, the seasonal and regional variations of biomass solid fuel mean that this clean energy source can only be utilized in specific periods, ultimately negatively impacting the regulation of industrial boiler loads.

[0003] Solid fuel gasification processes have been continuously developing, and the continuity and measurability of the heat generated by their gasification products are the biggest differences between gasification processes and raw fuels. In recent years, the gasification pyrolysis of biomass solid fuels has also begun to be applied in industrial production. Studies have shown that biomass gas combustion is more efficient than direct combustion of biomass solid fuels. Furthermore, the measurable calorific value and easy storage of biomass gas mean that it is not affected by load changes during power plant peak shaving. This invention provides a coal-fired boiler system and process for co-firing biomass gas, ensuring the efficient utilization of biomass energy while precisely controlling and reducing NO pollutants without altering existing coal-fired boiler technologies. x Emissions. Summary of the Invention

[0004] The purpose of this invention is to provide a coal-fired boiler system and process that incorporates biomass fuel gas, ensuring efficient utilization of biomass energy while precisely controlling and reducing NO pollutants without altering existing coal-fired boiler technologies. x Emissions.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a coal-fired boiler system for co-combustion of biomass fuel gas, applied to the air inlet side of the main combustion zone of a coal-fired boiler. The system includes a gasification device, a sampling device, and a flow control device. Biomass solid fuel and a gasifying agent generate biomass fuel gas within the gasification device. The biomass fuel gas is connected to the flow control device via a pipeline. The flow control device outputs the biomass fuel gas to the perimeter air outlet of the main combustion zone for co-combustion. The sampling device is installed on the pipeline between the gasification device and the flow control device to sample and detect the biomass fuel gas.

[0007] Furthermore, a purification device, a heat exchange device, and a gas storage tank are sequentially arranged between the gasification device and the sampling device. The purification device is used to remove dust and tar from the biomass gas, the heat exchange device is used to reduce the temperature of the biomass gas, and the gas storage tank is used to store the biomass gas.

[0008] Furthermore, the purification device specifically employs an electrostatic cyclone tar remover and a dust collector, and a collector for collecting tar and dust is provided at the bottom of the purification device.

[0009] Furthermore, the refrigerant in the heat exchange device is the secondary air from the coal-fired boiler, and the secondary air is preheated during the cooling process.

[0010] Furthermore, the gas storage tank is equipped with a temperature control instrument.

[0011] Furthermore, the flow control device includes a valve and a flow meter connected in sequence by pipelines, wherein the valve is specifically a flow control valve and the flow meter is specifically a rotor flow meter.

[0012] Accordingly, the present invention also provides a co-combustion process for a coal-fired boiler system that co-combusts biomass gas. The specific steps of using the aforementioned coal-fired boiler system to co-combust biomass gas include:

[0013] In the first step, the biomass solid fuel and gasifying agent are added to the gasification device in a certain proportion. Under the action of the gasifying agent, the biomass solid fuel undergoes pyrolysis and gasification under certain temperature and pressure conditions. The gasification product is primary biomass gas, which is purified in a purification device and cooled in a heat exchange device. The treated biomass gas is then stored in a gas storage tank. Subsequently, after opening the sampling valve, a small amount of gas is extracted from the gas storage tank using a sampling device to determine the composition and calorific value of the gas.

[0014] The second step involves performing thermodynamic calculations on the combustion of pure pulverized coal under rated operating conditions of the coal-fired boiler to obtain the total heat input to the furnace and the air-coal parameters under these conditions. While ensuring the total heat input to the furnace remains constant, based on the composition of the coal sample burned in the boiler, and also based on the biomass fuel composition determination and calorific value analysis results from the first step, thermodynamic calculations are performed for the co-firing of the biomass fuel to obtain the co-firing volumetric flow rate of the biomass fuel.

[0015] The third step involves co-firing the biomass gas. The perimeter vent is used as the biomass gas injection inlet, and valves and flow meters are used to regulate the inlet flow rate. In the main combustion zone, the primary air intake mixes with pulverized coal and undergoes vigorous combustion. The biomass gas introduced from the perimeter vent mixes with the high-temperature burning pulverized coal, serving as both input fuel and releasing heat. Furthermore, the reducing gases in the biomass gas components react with NO generated in the main combustion zone. x A reaction occurs, turning NO x Restored to N2.

[0016] Furthermore, in the first step, the gasifying agent is selected from air, water vapor, or oxygen. The biomass solid fuel reacts with the gasifying agent in a certain proportion to produce combustible gases such as alkanes, hydrogen, and carbon monoxide. The gasification product temperature is generally between 700 and 900°C. The main components of the biomass fuel gas include CH4, H2, CO, N2, and CO2, with CH4, H2, and CO accounting for 40% to 60%.

[0017] Furthermore, in the first step, the heat exchange device lowers the temperature of the biomass gas to 300℃~400℃, that is, the temperature of the biomass gas is close to the temperature of the secondary hot air.

[0018] Furthermore, in the second step, during the thermal calculation of the biomass gas co-firing operation, without changing or slightly adjusting the size of the perimeter vents, the biomass gas injection velocity is reasonably selected by comprehensively considering the composition and calorific value of the biomass gas and the design wind speed of the perimeter vents. The air inlet ratio of the primary vent is reduced, and the air inlet ratios of the burnout vents and secondary vents are appropriately adjusted to ensure that the velocity variation of each burner nozzle in the main combustion zone is within a reasonable range.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] This invention discloses a coal-fired boiler system that co-fires biomass gas. Biomass gas generated by a gasification device is injected into the perimeter tuyeres of the main combustion zone. The biomass gas is sampled and analyzed for composition and calorific value. Thermodynamic calculations are performed on the combustion of pure pulverized coal under the rated operating conditions of a given coal-fired boiler to obtain the total heat input to the furnace and the air-coal parameters under these conditions. While ensuring a constant total heat input to the furnace, thermodynamic calculations are performed based on the composition of the coal sample and the aforementioned biomass gas composition and calorific value analysis results to obtain the co-fired biomass gas volumetric flow rate. Therefore, an accurate co-fired biomass gas volumetric flow rate can be obtained, which is beneficial for the efficient utilization of biomass energy and the reduction of NOx emissions. The high-speed introduction of biomass gas from the perimeter tuyeres acts as a perimeter wind, increasing the rigidity of the primary airflow to prevent airflow deviation, cooling the primary air nozzles, and simultaneously aiding combustion and reducing NOx emissions.

[0021] Furthermore, the purification device combining an electrostatic cyclone descaling unit and a dust collector effectively removes tar and dust from the biomass gas, preventing environmental pollution from tar co-combustion and dust accumulation that clogs pipes. The collector facilitates regular centralized waste disposal. The air-cooled heat exchanger cools the high-temperature biomass gas while preheating the secondary air, improving waste heat utilization and saving energy. Temperature control instruments facilitate temperature control of the biomass gas in the storage tank. Valves and flow meters allow for precise control based on the co-combustion volumetric flow rate calculated thermally. The main components of the biomass gas include CH4, H2, CO, N2, and CO2, with CH4, H2, and CO accounting for 40%–60%, facilitating accurate determination of its composition and calorific value. The heat exchange device lowers the biomass gas temperature to a suitable range of 300℃–400℃, ensuring the biomass gas temperature is close to the secondary air temperature and preventing impact on the main combustion zone furnace, thus promoting stable combustion. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the structure of the coal-fired boiler system for co-firing biomass gas according to the present invention;

[0024] Figure 2 This is a schematic diagram of the air intake section of the main combustion zone of the present invention;

[0025] Figure 3 This is a schematic diagram of the combustion process of the present invention;

[0026] Explanation of reference numerals in the attached drawings: 1. Biomass solid fuel; 2. Gasifying agent; 3. Gasification device; 4. Purification device; 5. Collector; 6. Gas storage tank; 7. Temperature control instrument; 8. Sampling device; 9. Valve; 10. Flow meter; 11. Secondary air outlet; 12. Primary air outlet; 13. Secondary air box; 14. Combustion air outlet; 15. Main combustion zone; 16. Combustion zone; 17. Perimeter air outlet. Detailed Implementation

[0027] The core of this invention is to provide a coal-fired boiler system that co-fires biomass fuel gas, ensuring efficient utilization of biomass energy while precisely controlling and reducing NO pollutants without altering existing coal-fired boiler technologies. x Emissions.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Refer to the attached diagram. Figure 1 This is a schematic diagram of the structure of the coal-fired boiler system for co-firing biomass gas according to the present invention; Figure 2 This is a schematic diagram of the air intake section of the main combustion zone of the present invention; Figure 3 This is a schematic diagram of the combustion process of the present invention.

[0030] In one specific implementation, such as Figure 1 and Figure 2 As shown, a coal-fired boiler system for co-firing biomass gas is applied on the air inlet side of the main combustion zone 15 of a coal-fired boiler. It includes a gasification device 3, a sampling device 8, and a flow control device. Biomass solid fuel 1 and gasification agent 2 generate biomass gas in the gasification device 3. The biomass gas is connected to the flow control device through a pipeline. The flow control device outputs the biomass gas to the perimeter air outlet 17 of the main combustion zone 15 for co-firing. The sampling device 8 is installed on the pipeline between the gasification device 3 and the flow control device to sample and detect the biomass gas.

[0031] Biomass gas generated by the gasification device 3 is injected into the perimeter tuyeres 17 of the main combustion zone 15. The biomass gas is then sampled and tested by the sampling device 8 to determine its composition and calorific value. Thermodynamic calculations are performed on the combustion of pure pulverized coal under the rated operating conditions of a given coal-fired boiler to obtain the total heat input to the furnace and the air-coal parameters under these conditions. While ensuring a constant total heat input to the furnace, thermodynamic calculations are performed based on the composition of the coal sample burned in the boiler, and according to the aforementioned biomass gas composition determination and calorific value analysis results, to obtain the co-firing volumetric flow rate of the biomass gas. Therefore, an accurate co-firing volumetric flow rate of the biomass gas can be obtained, which is beneficial for the efficient utilization of biomass energy and the reduction of NOx emissions.

[0032] Because the calorific value per unit volume of biomass gas, the gasification product of biomass solid fuel, is much lower than that of pulverized coal, and the heat ratio under co-firing conditions is relatively small (5%–20%), a primary air nozzle of the same area must have a very high flow velocity. Peripheral air, as a portion of secondary air separated from the secondary air box, generally has a much higher flow velocity than pulverized coal jets, typically 30–40 m / s. The velocity of the biomass gas introduced into the peripheral air inlet 7 is very close to the velocity of the peripheral air, and will not impact the velocity field within the furnace, resulting in minimal changes in the temperature field. Therefore, the high-speed introduction of biomass gas from the peripheral air inlet 7 can function as peripheral air, increasing the rigidity of the primary air flow to prevent airflow deflection, cooling the primary air nozzle, and simultaneously aiding combustion and reducing NOx pollutants.

[0033] In one specific embodiment of the present invention, such as Figure 1 As shown, a purification device 4, a heat exchange device, and a gas storage tank 6 are sequentially arranged between the gasification device 3 and the sampling device 8. The purification device 4 is used to remove dust and tar from the biomass gas, the heat exchange device is used to reduce the temperature of the biomass gas, and the gas storage tank 6 is used to store the biomass gas.

[0034] Specifically, the purification device 4 adopts an electrostatic cyclone descaling device and a dust collector. The bottom of the purification device 4 is equipped with a collector 5 for collecting tar and dust. The tar and dust in the collector 5 are treated regularly to avoid environmental pollution.

[0035] Specifically, the heat exchange device adopts an air-cooled heat exchanger, and the refrigerant of the heat exchanger is the secondary air of the coal-fired boiler. The secondary air is preheated during the cooling process.

[0036] Specifically, a temperature control instrument 7 is installed on the top of the gas storage tank 6.

[0037] The purification device 4, which combines an electrostatic cyclone descaling unit and a dust collector, effectively removes tar and dust from the biomass gas, preventing environmental pollution from tar co-combustion and dust accumulation that clogs pipes. The collector 5 facilitates regular centralized waste disposal. The air-cooled heat exchanger cools the high-temperature biomass gas while preheating the secondary air, improving waste heat utilization and saving energy. The temperature control instrument 7 facilitates temperature control of the biomass gas in the gas storage tank 6.

[0038] In one specific embodiment of the present invention, such as Figure 1 As shown, the flow control device includes a valve 9 and a flow meter 10 connected in sequence by pipelines. The valve 9 is specifically a flow control valve, and the flow meter 10 is specifically a rotor flow meter.

[0039] The installation of valve 9 and flow meter 10 facilitates the control of the co-firing volume flow rate of biomass gas obtained from thermal calculations, enabling precise control.

[0040] A co-combustion process for a coal-fired boiler system that incorporates biomass fuel gas, such as Figure 3 The specific working steps of using the above-mentioned coal-fired boiler system with biomass co-combustion include:

[0041] In the first step, biomass solid fuel 1 and gasifying agent 2 are added to the gasification device 3 in a certain proportion. Under the action of gasifying agent 2, biomass solid fuel 1 undergoes pyrolysis and gasification under certain temperature and pressure conditions. The gasification product is primary biomass gas, which is purified in the purification device 4 and cooled in the heat exchange device. The treated biomass gas is then stored in the gas storage tank 6. Subsequently, after opening the sampling valve, a small amount of gas is extracted from the gas storage tank 6 using the sampling device 8 to conduct gas composition determination and calorific value analysis.

[0042] The second step involves performing thermodynamic calculations on the combustion of pure pulverized coal under rated operating conditions of the coal-fired boiler to obtain the total heat input to the furnace and the parameters of the coal and air under these conditions. While ensuring that the total heat input to the furnace remains constant, based on the composition of the coal sample burned in the boiler, and also based on the results of the biomass gas composition determination and calorific value analysis in the first step, thermodynamic calculations are performed for the co-firing of biomass gas to obtain the co-firing volumetric flow rate of the biomass gas.

[0043] The third step involves co-firing biomass gas. Perimeter vent 17 is used as the biomass gas injection inlet, and valve 9 and flow meter 10 are used to regulate the inlet flow rate. In the main combustion zone 15, the air intake from primary vent 12 mixes with pulverized coal and undergoes vigorous combustion. The biomass gas introduced from perimeter vent 17 mixes with the high-temperature burning pulverized coal, serving as both input fuel for combustion and heat release. Furthermore, the reducing gases in the gas components react with NO generated in the main combustion zone 15. x A reaction occurs, turning NO x It is reduced to N2. Furthermore, in the burnout zone 16 above the main combustion zone 15, the unburned coal powder is further burned by the air intake at the burnout vent 14, and NO is reduced to N2. x Further reduction.

[0044] In the first step, the gasifying agent 2 is selected from air, water vapor, or oxygen. Biomass solid fuel 1 reacts with gasifying agent 2 in a certain proportion to produce combustible gases such as alkanes, hydrogen, and carbon monoxide. The gasification product temperature is generally between 700℃ and 900℃. The main components of biomass fuel gas include CH4, H2, CO, N2, and CO2, with CH4, H2, and CO accounting for 40% to 60%.

[0045] In the first step, the heat exchange device lowers the temperature of the biomass gas to a suitable range of about 300℃ to 400℃, that is, the temperature of the biomass gas is close to the temperature of the secondary hot air.

[0046] The second step involves the thermal calculation of the biomass gas co-firing condition, which includes the following formula:

[0047] The volumetric flow rate when co-firing biomass fuel gas is:

[0048]

[0049] In the formula: γ is the ratio of the heat generated by biomass gas to the total heat input into the boiler, which is taken as 5% to 20%; Q is the total heat input into the furnace, kJ / s; Q v The volumetric calorific value of biomass gas is expressed in kJ / m³. 3 V g The required biomass gas volume flow rate (m) for co-firing. 3 / s.

[0050] The rate of biomass combustion is:

[0051]

[0052] In the formula: V g S is the inlet velocity of biomass gas, m / s; S is the total area of ​​the biomass gas nozzle, m². 2 .

[0053] Without changing or slightly adjusting the size of the perimeter vent 17, the biomass gas injection velocity is rationally selected based on the composition and calorific value of the biomass gas, taking into account the design wind speed of the perimeter vent 17. The air inlet ratio of the primary vent 12 is reduced, and the air inlet ratios of the burnout vent 14 and secondary vent 11 are appropriately adjusted to ensure that the velocity variation of each burner nozzle within the main combustion zone 15 is within a reasonable range. A biomass gas blending ratio of 5% to 20% is most suitable.

[0054] In addition, by sampling and testing the flue gas emitted from the coal-fired boiler, the co-combustion flow rate of the biomass gas can be adjusted based on the analysis of the exhaust gas composition, thereby further reducing the pollutant content in the exhaust gas and improving fuel utilization efficiency.

[0055] This invention relates to a coal-fired boiler system that co-fires biomass gas. Biomass gas generated by a gasification device 3 is injected into the perimeter tuyeres 17 of the main combustion zone 15. The biomass gas is sampled and tested by a sampling device 8 to determine its composition and calorific value. Thermodynamic calculations are performed on the combustion of pure pulverized coal under the rated operating conditions of a given coal-fired boiler to obtain the total heat input to the furnace and the air-coal parameters under these conditions. While ensuring a constant total heat input to the furnace, thermodynamic calculations are performed based on the composition of the coal sample and the aforementioned biomass gas composition and calorific value analysis results to obtain the co-fired biomass gas volumetric flow rate. Therefore, an accurate co-fired biomass gas volumetric flow rate can be obtained, which is beneficial for the efficient utilization of biomass energy and the reduction of NOx emissions. The high-speed introduction of biomass gas from the perimeter tuyeres 7 acts as a perimeter wind, increasing the rigidity of the primary airflow to prevent airflow deviation, cooling the primary air nozzles, and simultaneously aiding combustion and reducing NOx emissions. Furthermore, the purification device 4, which combines an electrostatic cyclone descaling unit and a dust collector, effectively removes tar and dust from the biomass gas, preventing environmental pollution from tar co-combustion and avoiding dust accumulation that clogs pipes. The collector 5 facilitates regular centralized waste disposal. The air-cooled heat exchanger cools the high-temperature biomass gas while preheating the secondary air, improving waste heat utilization and saving energy. The temperature controller 7 facilitates temperature control of the biomass gas in the storage tank 6. The valve 9 and flow meter 10 facilitate precise control based on the co-combustion volumetric flow rate of the biomass gas calculated thermally. The main components of biomass gas include CH4, H2, CO, N2, and CO2, among which CH4, H2, and CO account for 40% to 60%, facilitating accurate determination of its composition and calorific value. The heat exchange device reduces the temperature of the biomass gas to a suitable range of 300℃ to 400℃, meaning that the temperature of the biomass gas is close to that of the secondary hot air, which will not impact the furnace in the main combustion zone 15 and is conducive to stable combustion.

[0056] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A process for co-firing of a coal fired boiler system with a co-fired biomass gas, characterized by: The biomass gas is mixed with the coal-fired boiler system, and the specific working steps include: In the first step, the biomass solid fuel (1) and the gasifying agent (2) are put into the gasification device (3) according to a certain proportion, and under the action of the gasifying agent (2), the biomass solid fuel (1) is pyrolyzed and gasified under certain temperature and pressure conditions; the product of gasification is the primary biomass gas, which is purified in the purification device (4) and cooled in the heat exchange device, and the treated biomass gas is stored in the gas storage tank (6); then the sampling valve is opened, and a small amount of gas in the gas storage tank (6) is extracted by the sampling device (8) to determine the composition and analyze the calorific value of the gas; In the second step, the thermal calculation of pure coal combustion under the rated condition of the coal-fired boiler is carried out to obtain the total heat input into the furnace and the wind-coal parameters under the condition; under the condition of keeping the total heat input into the furnace unchanged, the thermal calculation of the biomass gas mixing combustion condition is carried out according to the composition of the coal sample and the results of the biomass gas composition determination and calorific value analysis in the first step to obtain the volume flow of the biomass gas mixing combustion; Thirdly, when the biomass gas is mixed with the coal, the peripheral air inlet (17) is used as the injection inlet of the biomass gas, and the valve (9) and the flow meter (10) are used to adjust the inlet flow of the biomass gas; in the main combustion zone (15), the primary air inlet (12) mixes with the pulverized coal and then burns fiercely, and the biomass gas from the peripheral air inlet (17) mixes with the high-temperature burning pulverized coal, which burns to release heat on one hand, and on the other hand, the reducing gas in the biomass gas component reduces the NOx produced in the main combustion zone (15) to N2. X X The NOx is reduced to N2.​ The biomass gas mixing combustion coal-fired boiler system is applied to the air inlet side of the main combustion zone (15) of the coal-fired boiler, and is characterized by comprising a gasification device (3), a sampling device (8) and a flow control device, the biomass solid fuel (1) and the gasifying agent (2) generate the biomass gas in the gasification device (3), the biomass gas is connected to the flow control device through a pipeline, the flow control device outputs the biomass gas to the peripheral air port (17) of the main combustion zone (15) for mixing combustion, and the sampling device (8) is arranged on the pipeline between the gasification device (3) and the flow control device to sample and detect the biomass gas; The purification device (4), the heat exchange device and the gas storage tank (6) are sequentially arranged between the gasification device (3) and the sampling device (8), the purification device (4) is used for removing the dust and tar of the biomass gas, the heat exchange device is used for reducing the temperature of the biomass gas, and the gas storage tank (6) is used for storing the biomass gas; The temperature of the biomass gas is reduced to 300-400℃ by the heat exchange device.

2. The process of firing the coal based boiler system with admixture of biomass based gas as claimed in claim 1 wherein: The purification device (4) specifically adopts the electrostatic cyclone tar remover and the dust remover, and the collector (5) for collecting tar and dust is arranged at the bottom of the purification device (4).

3. The process of firing the coal based boiler system with admixture of biomass based gas as claimed in claim 1 wherein: The coolant of the heat exchange device is the secondary air of the coal-fired boiler, and the secondary air is preheated in the cooling process.

4. The process of firing the coal based boiler system with admixture of biomass gas as claimed in claim 1 wherein: The temperature control instrument (7) is arranged on the gas storage tank (6).

5. The process of firing the coal based boiler system with admixture of biomass gas as claimed in claim 1 wherein: The flow control device comprises a valve (9) and a flow meter (10) which are sequentially connected by pipelines, the valve (9) specifically adopts the flow control valve, and the flow meter (10) specifically adopts the rotor flow meter.

6. The process of firing the coal based boiler system with admixture of biomass gas as claimed in claim 1 wherein: The gasification agent (2) is selected from air, water vapor or oxygen in the first step. The biomass solid fuel (1) is reacted with the gasification agent (2) in a certain proportion to generate alkanes, hydrogen and carbon monoxide, and the temperature of the gasification product is 700-900 DEG C. The components of the biomass gas include CH4, H2, CO, N2 and CO2, wherein the content of CH4, H2 and CO accounts for 40-60%.

7. The process of firing the coal based boiler system with admixture of biomass gas as claimed in claim 1 wherein: In the second step, in the thermal calculation of the biomass gas blending combustion condition, the biomass gas injection speed is reasonably selected by comprehensively considering the composition and calorific value of the biomass gas and the design wind speed of the peripheral tuyere (17) without changing or slightly adjusting the size of the peripheral tuyere (17); the primary air inlet ratio is reduced, and the ratios of the overfire air inlet (14) and the secondary air inlet (11) are properly adjusted, so that the speed variation of each burner nozzle in the main combustion zone (15) is within a reasonable range.

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