System and method for coupling alternative fuel pyrolysis gasification and cement production line

Abstract

The invention discloses an alternative fuel pyrolysis gasification and cement production line coupling system and method. The system comprises a decomposing furnace, a smoke chamber, an n-stage raw material preheating system, a pyrolysis gasification device and an ash cooling and conveying system, a raw material distributing device is arranged on a blanking pipe of an (n-1)-stage cyclone cylinder in the n-stage raw material preheating system; an outlet of the raw material distributing device is respectively communicated with a raw material inlet of the decomposing furnace and a hot raw material inlet of the pyrolysis gasification device; the pyrolysis gasification device comprises a suspension section positioned at the upper part, a transition section and a boiling section positioned at the middle part, and an air distribution system and a slag outlet positioned at the lower part; a tertiary air inlet is formed in the side surface of the suspension section, and a flue gas outlet communicated with the decomposing furnace is formed in the upper part; an alternative fuel inlet, a bed material inlet and a hot raw material inlet are respectively formed in the side surface of the middle part; and the slag outlet is respectively communicated with the smoke chamber and the ash cooling and conveying system. The heat utilization efficiency of alternative fuel and the substitution rate of fossil fuel of the cement kiln can be greatly improved.

Description

Technical Field

[0001] The present invention relates to a system and method for utilizing alternative fuels, and in particular to a system and method for coupling pyrolysis and gasification of alternative fuels with a cement production line. Background Art

[0002] In recent years, the use of alternative fuels has become an important technical path for the cement industry to reduce carbon emissions, reduce costs and increase efficiency. More and more cement plants have begun to use alternative fuels as cement decomposition furnace fuel, partially or completely replacing traditional fossil fuels.

[0003] The alternative fuel gasification technology is to pyrolyze and gasify the alternative fuel into carbon-containing fly ash and combustible gas, and then send it into the decomposition furnace for combustion. Since combustible gas and carbon-containing fly ash are easier to burn, they can be fully burned under the drive of the high-speed airflow in the decomposition furnace. This technology has little impact on the decomposition furnace and the alternative fuel burns fully. Such as Conch's CKK gasifier and Jinyu's continuous pyrolysis gasifier. However, this type of technology also has certain problems: since pyrolysis and gasification is an endothermic reaction, in order to maintain the reaction temperature in the furnace (generally ≥550℃), low calorific value alternative fuels require a larger air-fuel ratio and need to be fed with more air, resulting in low calorific value of combustible gas, low heat utilization, and large exhaust loss.

[0004] Patent CN201010532911.0 discloses a waste treatment device for introducing the pyrolysis gas of waste into a cement decomposition furnace, which is provided with a gasifier for gasifying the waste to generate pyrolysis gas, and a gas delivery channel for delivering the generated pyrolysis gas to the decomposition furnace while keeping the carbon and ash contained intact. The pyrolysis gas is introduced into the decomposition furnace in a form in which the pyrolysis gas does not directly interfere with the mainstream of the waste gas flow from the burning furnace or the clinker cooler, so as to prevent it from being scraped and fully burnt. In this way, the existing cement manufacturing equipment is effectively utilized to achieve sanitary treatment of waste at a low cost. However, the gasifier for generating pyrolysis gas in the patent uses air as a fluidizing medium. The pyrolysis and gasification process of the waste is an endothermic reaction, and the reaction temperature is generally ≥550°C. The required heat source is obtained through the oxidation combustion reaction of a part of the combustibles and oxygen. In order to maintain the reaction temperature in the furnace, the alternative fuel requires a larger air-fuel ratio, and more air needs to be introduced, resulting in the problems of low calorific value of the combustible gas, low heat utilization rate, and large exhaust loss.

[0005] Therefore, how to reduce the air-fuel ratio required for alternative fuels and improve heat utilization is a technical problem that needs to be solved urgently. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a system for coupling pyrolysis and gasification of alternative fuels with a cement production line, which can fully utilize the high-temperature heat source of the cement burning system, reduce the air-fuel ratio required for alternative fuels, and effectively improve the heat utilization efficiency of alternative fuels in cement kilns and the replacement rate of fossil fuels.

[0007] The second object of the present invention is to provide a method for coupling alternative fuel pyrolysis and gasification with a cement production line.

[0008] Technical solution: The system of coupling alternative fuel pyrolysis and gasification with a cement production line described in the present invention comprises a decomposition furnace, a smoke chamber, an n-stage raw material preheating system, a pyrolysis and gasification device, and an ash cooling and conveying system; a raw material dividing device is provided on the discharge pipe of the n-1-stage cyclone in the n-stage raw material preheating system, and the outlet of the raw material dividing device is respectively connected with the raw material inlet of the decomposition furnace and the hot raw material inlet of the pyrolysis and gasification device; the pyrolysis and gasification device comprises a suspension section located at the upper part, a transition section and a boiling section located in the middle part, and an air distribution system and a slag outlet located at the lower part; a tertiary air inlet connected with the tertiary air outlet pipeline of the decomposition furnace is provided on the side of the suspension section, and a smoke outlet connected with the decomposition furnace is provided on the upper part; an alternative fuel inlet, a bed material inlet and a hot raw material inlet are respectively provided on the side of the middle part of the pyrolysis and gasification device; the slag outlet is respectively connected with the smoke chamber and the ash cooling and conveying system.

[0009] Wherein, the air distribution system includes an air distribution pipe or an air distribution plate arranged at the lower part of the pyrolysis gasification device, and an air blower connected to the air distribution pipe or the air distribution plate.

[0010] Wherein, the tertiary air inlet is connected to the suspension section in a rotary cutting direction.

[0011] Wherein, the pyrolysis gasification device is a bubbling fluidized bed structure.

[0012] Among them, a first air volume regulating valve is provided on the tertiary air outlet pipeline; a second air volume regulating valve is provided on the connecting pipeline between the smoke outlet of the pyrolysis gasification device and the decomposition furnace.

[0013] Wherein, the slag outlet is respectively connected with the smoke chamber and the ash cooling and conveying system through the ash distribution device.

[0014] The ash distributing device comprises an ash discharge valve and a tee connected to the ash discharge valve. The tee outlet is provided with two channels, one channel is connected to the smoke chamber, and the other channel is connected to the ash cooling and conveying system.

[0015] The method for coupling alternative fuel pyrolysis and gasification with a cement production line according to the present invention comprises the following steps:

[0016] The bed material is filled in from the bed material inlet of the pyrolysis gasification device. The high-temperature hot raw material from the raw material distribution device enters the middle part of the pyrolysis gasification device from the hot raw material inlet. Driven by the fluidized air of the air distribution system, the high-temperature hot raw material exchanges heat with the bed material. After the temperature in the middle part of the pyrolysis gasification device rises, the alternative fuel is fed in from the alternative fuel inlet of the pyrolysis gasification device. The alternative fuel, high-temperature hot raw material, fluidized air and heat-storing bed material are fully mixed, and heat and mass transfer reactions occur: the combustible gas and carbon-containing fly ash generated by the pyrolysis and gasification of the alternative fuel carry the hot raw material into the suspension section;

[0017] In the pyrolysis gasification device, the combustible gas and carbon-containing fly ash encounter the high-temperature gas from the tertiary air duct, and burn rapidly to release heat. The hot raw meal reaches the decomposition temperature and decomposes to absorb heat. The flue gas, ash, and unreacted combustible gas, carbon-containing fly ash, and hot raw meal generated in the suspension section enter the decomposition furnace from the flue gas outlet of the pyrolysis gasification device. The combustible gas and carbon-containing fly ash enter the decomposition furnace and continue to burn and release heat when encountering oxygen, thereby replacing part of the fuel coal.

[0018] The unreacted part of the alternative fuel is further pyrolyzed and gasified under the scouring of the fluidized bed material and raw meal and in a high-temperature environment until the reaction is complete; the impurities and heavy incombustibles mixed in the alternative fuel fall into the lower part of the pyrolysis and gasification device, are discharged from the pyrolysis and gasification device through the slag outlet, and are sent to the decomposition furnace or the ash cooling and conveying system.

[0019] Among them, the temperature control of the middle part of the pyrolysis gasification device: when the temperature at this place is too high, increase the feeding amount of hot raw materials, and control the temperature in the incinerator through the decomposition and absorption of heat by the hot raw materials; when the temperature at this place is too low, increase the air supply of the air distribution system; the air supply fan inlet of the air distribution system is connected to air or oxygen-rich gas, and the oxygen in the generated fluidizing air reacts with the alternative fuel to generate heat to ensure the pyrolysis gasification temperature in the middle part of the pyrolysis gasification device, so that its temperature is always at the appropriate pyrolysis gasification temperature for various alternative fuels;

[0020] Temperature control of the upper part of the pyrolysis gasification device: when the temperature there is too high, the opening of the first air volume regulating valve is reduced to reduce the supply of tertiary air; when the temperature there is too low, the opening of the first air volume regulating valve is increased to increase the supply of tertiary air.

[0021] Among them, the pressure control inside the pyrolysis gasification device: the flue gas access point of the pyrolysis gasification device is connected to the upper position of the decomposition furnace, and the wind speed and pressure of the flue gas entering the pyrolysis gasification device are controlled by adjusting the opening of the second air volume regulating valve; or, the feed amount of the alternative fuel and the air supply amount of the blower are adjusted to adjust the gas production of the pyrolysis gasification reaction of the alternative fuel, thereby playing a role in regulating the internal pressure of the pyrolysis gasification device.

[0022] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0023] (1) The present invention utilizes the high-temperature raw material of the cement burning system as the heat source for pyrolysis and gasification of the alternative fuel, and adopts a pyrolysis and gasification device to pyrolyze and gasify the alternative fuel. The air-fuel ratio required by the pyrolysis and gasification device is small, the calorific value of the combustible gas generated in the pyrolysis and gasification process of the alternative fuel is high, the amount of flue gas generated by the entire system is small, the exhaust loss is small, and thus the heat utilization rate of the alternative fuel is high and the fossil fuel replacement ratio is high; (2) The tertiary air is introduced into the upper part of the pyrolysis and gasification device to premix with the generated pyrolysis and gasification flue gas, which can improve its burnout rate and reduce the carbon monoxide concentration at the outlet of the preheater of the burning system, further improving the heat utilization rate of the alternative fuel. At the same time, it can also maintain the internal temperature of the pyrolysis and gasification device and reduce the fluidizing air volume; (3) The slag outlet of the pyrolysis and gasification device is connected with The material distribution device can deliver the ash to the smoke chamber of the decomposition furnace or the ash cooling and conveying system. The ash is cooled by the cooling and conveying system and conveyed to the raw material batching system or other places. It also has a certain adaptability to alternative fuels containing a large amount of non-combustible impurities; (4) The preheating process of the bed material and the furnace of the pyrolysis gasification device can utilize high-temperature hot raw materials and tertiary air, eliminating the need for external burners and saving fossil fuels; (5) The pyrolysis gasification device can handle multiple types of alternative fuels and adapt to various real-life situations such as complex sources of alternative fuels, large fluctuations in components, and large differences in physical and chemical components; (6) The system of the present invention can greatly improve the heat utilization efficiency of alternative fuels and the fossil fuel substitution rate of cement kilns, and it also has a certain adaptability to low-calorific value and inferior alternative fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the system structure of the alternative fuel pyrolysis gasification coupled with a cement production line of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the pyrolysis gasification device of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0027] like Figure 1 As shown, the present invention provides a system for coupling alternative fuel pyrolysis and gasification with a cement production line, comprising a decomposition furnace 1, a smoke chamber 2, a tertiary air duct 3, an n-stage raw material preheating system, a raw material dividing device 6, a pyrolysis and gasification device 7, an ash dividing device, and an ash cooling and conveying system 12.

[0028] A raw material distributor 6 is provided at the discharge port of the n-1 stage cyclone 5 in the n stage raw material preheating system, and the outlet of the raw material distributor 6 is respectively connected with the raw material inlet of the decomposition furnace 1 and the hot raw material inlet of the pyrolysis gasification device; the pyrolysis gasification device comprises a suspension section 701 located at the upper part, a transition section and a boiling section 708 located in the middle part, and an air distribution system and a slag outlet 706 located at the lower part; a tertiary air inlet connected with the tertiary air outlet pipeline of the decomposition furnace 1 is provided on the side of the suspension section, and a flue gas outlet connected with the decomposition furnace 1 is provided on the upper part; an alternative fuel inlet, a bed material inlet and a hot raw material inlet are provided on the side of the middle part of the pyrolysis gasification device; the slag outlet is respectively connected with the smoke chamber 2 and the ash cooling and conveying system 12.

[0029] The decomposition furnace 1 of the present invention is a decomposition furnace in a conventional new type dry cement burning system; the smoke chamber 2 is a smoke chamber in a conventional new type dry cement burning system; the raw material dividing device 6 is a three-way dividing device installed on the discharge pipe of the n-1 stage cyclone 5, that is, on the raw material inlet pipe of the decomposition furnace 1. For a cement burning system adopting a five-stage preheating system, the raw material dividing device 6 is installed on the discharge pipe of the C4 cyclone; for a cement burning system adopting a six-stage preheating system, the raw material dividing device 6 is installed on the discharge pipe of the C5 cyclone. This embodiment is a five-stage preheating system, and the raw material dividing device 6 is installed on the discharge pipe of the C4 cyclone. The raw material dividing device 6 divides the preheated raw material into two paths, one path is fed into the decomposition furnace 1, and the other path is fed into the hot raw material inlet of the pyrolysis gasification device 7.

[0030] The pyrolysis gasification device 7 adopts a bubbling fluidized bed structure, with a suspension section 701 at the top, a tertiary air inlet 710 provided on the side, and a flue gas outlet at the top; the tertiary air inlet 710 is connected to the suspension section 701 in the rotary cutting direction, which is more conducive to mixing with the internal flue gas; the tertiary air inlet 710 is connected by the outlet pipeline of the tertiary air duct 3, and a first air volume regulating valve 4 is provided on the outlet pipeline; the flue gas outlet is connected to the decomposition furnace 1, and a second air volume regulating valve 9 is provided on the connected flue gas pipeline; the middle part 708 of the pyrolysis gasification device is a transition section and a boiling section, and an alternative fuel inlet 703, a bed material inlet 702 and a hot raw material inlet 709 are provided on the side respectively; the lower part 707 of the pyrolysis gasification device is provided with an air distribution system and a slag outlet 706; the air distribution system of the present invention includes an air distribution pipe 705 and a blower 8 connected to the air distribution pipe 705; the slag outlet 706 is connected to the ash and slag distribution device.

[0031] The ash distribution device of the present invention comprises an ash discharge valve 10, which has a sealing function. The ash discharge valve is connected to a tee 11, and the outlet of the tee 11 is divided into two channels, one of which is connected to the smoke chamber 2, and the other is connected to the ash cooling and conveying system 12. The destination of the ash is determined according to the amount, composition and influence on the stable operation of the cement clinker burning system: when the influence of the ash directly entering the decomposition furnace 1 on the stable operation of the cement clinker burning system is acceptable, the distribution device sends the ash into the decomposition furnace 1; otherwise, the distribution device sends the ash into the ash cooling and conveying system 12.

[0032] The ash cooling and conveying system 12 is used to cool the ash and convey the ash to a raw material batching station to participate in cement raw material batching or to other places for comprehensive utilization.

[0033] The process flow of the above system of the present invention is as follows:

[0034] The bed material is filled into the bed material inlet 702 of the pyrolysis gasification device 7. The high-temperature hot raw material of about 800°C of the C4 cyclone enters the middle part 708 of the pyrolysis gasification device from the hot raw material inlet 709 through the raw material distributor 6. Driven by the fluidized air of the air distribution system, the high-temperature hot raw material exchanges heat with the bed material. After the temperature of the middle part of the pyrolysis gasification device rises, the alternative fuel is fed into the alternative fuel inlet 703 of the pyrolysis gasification device 7. The alternative fuel, the high-temperature hot raw material, the fluidized air and the heat-storing bed material are fully mixed, and a rapid heat and mass transfer reaction occurs. The alternative fuel is rapidly pyrolyzed and gasified. The pyrolysis and gasification reaction temperature is 300-800°C. The generated combustible gas and carbon-containing fly ash carry the hot raw material into the suspension section 701. In the upper suspension section 701 of the pyrolysis gasification device 7, the combustible gas and the carbon-containing fly ash encounter the high-temperature gas from the tertiary air duct 3, and burn rapidly to release heat. When the hot raw material reaches the decomposition temperature, it decomposes and absorbs heat. The carbon dioxide generated when the calcium carbonate in the hot raw material decomposes will be consumed by reducing molecules such as hydrogen and methane generated by pyrolysis and gasification in the alternative fuel, thereby effectively promoting the positive decomposition of calcium carbonate, promoting the formation of calcium oxide, and reducing the temperature during the decomposition of calcium carbonate; the flue gas, ash, unreacted combustible gas, carbon-containing fly ash and hot raw material finally produced by the pyrolysis and gasification device 7 enter the decomposition furnace 1 from the flue gas outlet 711 of the pyrolysis and gasification device 7; the combustible gas and carbon-containing fly ash enter the decomposition furnace 1 and continue to burn and release heat when encountering oxygen, further replacing part of the fuel coal.

[0035] The unreacted part of the alternative fuel, such as flame-retardant and large-sized organic matter, is further pyrolyzed and gasified under the scouring and high-temperature environment of the fluidized bed material and raw meal until the reaction is complete; impurities and heavy incombustibles mixed in the alternative fuel fall into the lower part of the pyrolysis and gasification device and are discharged from the pyrolysis and gasification device 7 through the slag outlet 706; the ash discharged from the slag outlet 706 enters the ash distribution device, and the destination of the ash is determined according to the amount, composition and influence on the stable operation of the cement clinker burning system: when the influence of the ash directly entering the decomposition furnace on the stable operation of the cement clinker burning system is acceptable, the ash distribution device sends the ash to the decomposition furnace 1; otherwise, the ash distribution device sends the ash to the ash cooling and conveying system 12. The ash cooling and conveying system 12 is used to cool the ash and convey the ash to the raw material batching station to participate in the cement raw meal batching or other places for comprehensive utilization.

[0036] Temperature control of the middle part 708 of the pyrolysis and gasification device: when the temperature there is too high, increase the feed amount of hot raw material, and control the temperature in the incinerator by decomposing and absorbing heat from the hot raw material; when the temperature there is too low, increase the air supply of the air distribution system; a certain amount of air or oxygen-rich gas is connected to the inlet of the blower 8 of the air distribution system, which is pressurized and sent into the air distribution pipe 705 through the fluidizing air inlet 704. The oxygen in the fluidizing air generated by the air distribution pipe 705 undergoes an oxidation reaction with the alternative fuel to generate heat to ensure the pyrolysis and gasification reaction temperature of the middle part 708 of the pyrolysis and gasification device, so that its temperature is always at a suitable pyrolysis and gasification temperature for various alternative fuels.

[0037] Temperature control of the upper suspension section 701 of the pyrolysis gasification device 7: when the temperature there is high, the tertiary air supply is reduced by reducing the opening of the first air volume regulating valve 4; when the temperature there is low, the tertiary air supply is increased by increasing the opening of the first air volume regulating valve 4.

[0038] Pressure control inside the pyrolysis and gasification device 7: The flue gas access point of the pyrolysis and gasification device 7 is connected to the upper position of the decomposition furnace 1 as much as possible, and the wind speed and pressure of the flue gas entering the pyrolysis and gasification device 7 are mainly controlled by adjusting the opening of the second air volume regulating valve 9; when necessary, the feed amount of the alternative fuel and the air supply amount of the blower 8 are adjusted to adjust the gas production of the pyrolysis and gasification reaction of the alternative fuel, which can also play a role in regulating the internal pressure of the pyrolysis and gasification device 7.

[0039] The bed material of the pyrolysis gasification device 7 can be quartz sand or screened slag, and the bed material is fed through the bed material feeding port 702. The blower 8 of the pyrolysis gasification device 7 can blow in air, oxygen-rich gas and the flue gas discharged from the first-stage preheater in the raw material preheating system; for alternative fuels with high calorific value, pyrolysis gasification can be completed by relying solely on high-temperature hot raw materials and tertiary air, and the fluidizing air is only used to maintain the fluidization state of the bed material. At this time, the blower 8 is used to feed the flue gas discharged from the first-stage preheater in the raw material preheating system of the cement burning system into the pyrolysis gasification device 7; for low-calorific value, flame-retardant, and low-quality alternative fuels, pyrolysis gasification cannot be completed by relying solely on high-temperature hot raw materials and tertiary air. The fluidizing air is used to maintain the fluidization of the bed material and provide oxygen. At this time, the blower 8 blows in air or oxygen-rich gas.

Claims

1. A system for coupling alternative fuel pyrolysis gasification with a cement production line, characterized in that: The invention comprises a decomposition furnace (1), a smoke chamber (2), an n-stage raw material preheating system, a pyrolysis gasification device (7), and an ash cooling and conveying system (12); a raw material distribution device (6) is provided on the feed pipe of the n-1-stage cyclone (5) in the n-stage raw material preheating system, and the outlet of the raw material distribution device (6) is respectively connected to the raw material inlet of the decomposition furnace (1) and the hot raw material inlet (709) of the pyrolysis gasification device (7); the pyrolysis gasification device (7) comprises a suspension section (701) located at the upper part, a transition section (708) located in the middle part, and a boiling section , an air distribution system and a slag outlet (706) located at the lower part (707); a tertiary air inlet (710) connected to the tertiary air outlet pipeline of the decomposition furnace (1) is provided on the side of the suspension section (701), and a smoke outlet (711) connected to the decomposition furnace (1) is provided on the upper part; an alternative fuel inlet (703), a bed material inlet (702) and a hot raw material inlet (709) are respectively provided on the side of the middle part (708) of the pyrolysis gasification device; the slag outlet (706) is respectively connected to the smoke chamber (2) and the ash cooling and conveying system (12).

2. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 1 is characterized in that: The air distribution system comprises an air distribution pipe (705) or an air distribution plate arranged at the lower part (707) of the pyrolysis gasification device, and an air blower (8) connected to the air distribution pipe (705) or the air distribution plate via a fluidizing air inlet (704).

3. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 1, characterized in that: The tertiary air inlet (710) is connected to the suspension section (701) in a rotary cutting direction.

4. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 1, characterized in that: The pyrolysis and gasification device (7) is a bubbling fluidized bed structure.

5. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 1, characterized in that: A first air volume regulating valve (4) is provided on the tertiary air outlet pipeline; and a second air volume regulating valve (9) is provided on the connecting pipeline between the smoke outlet (711) of the pyrolysis gasification device (7) and the decomposition furnace (1).

6. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 1, characterized in that: The slag outlet (706) is connected to the ash cooling and conveying system (12) via an ash distribution device.

7. The system of coupling alternative fuel pyrolysis gasification with cement production line according to claim 6, characterized in that: The ash distribution device comprises an ash discharge valve (10) and a tee (11) connected to the ash discharge valve (10); the outlet of the tee (11) is provided with two channels, one channel is connected to the smoke chamber (2), and the other channel is connected to the ash cooling and conveying system (12).

8. A method for coupling alternative fuel pyrolysis gasification with a cement production line, characterized in that: The following steps are involved: The bed material is filled in from the bed material inlet (702) of the pyrolysis gasification device (7), and the high-temperature hot raw material from the raw material distribution device (6) enters the middle part (708) of the pyrolysis gasification device from the hot raw material inlet (709). Driven by the fluidizing air of the air distribution system, the high-temperature hot raw material exchanges heat with the bed material. After the temperature of the middle part of the pyrolysis gasification device rises, the alternative fuel is fed in from the alternative fuel inlet (703) of the pyrolysis gasification device (7). The alternative fuel, the high-temperature hot raw material, the fluidizing air and the heat-storing bed material are fully mixed, and heat and mass transfer reactions occur: the combustible gas and carbon-containing fly ash generated by the pyrolysis and gasification of the alternative fuel carry the hot raw material into the suspension section (701); In the pyrolysis gasification device (7), the combustible gas and the carbon-containing fly ash meet the high-temperature gas from the tertiary air duct (3) and burn to release heat. The hot raw material reaches the decomposition temperature and decomposes to absorb heat. The flue gas, ash, and unreacted combustible gas, carbon-containing fly ash, and hot raw material generated in the suspension section (701) enter the decomposition furnace (1) from the flue gas outlet (711) of the pyrolysis gasification device (7). The combustible gas and the carbon-containing fly ash enter the decomposition furnace (1) and continue to burn and release heat when they meet oxygen, thereby replacing part of the fuel coal. The unreacted part of the alternative fuel is further pyrolyzed and gasified under the scouring of the fluidized bed material and raw meal and in the high temperature environment until the reaction is complete; the impurities and heavy incombustibles mixed in the alternative fuel fall into the lower part (707) of the pyrolysis and gasification device, are discharged from the pyrolysis and gasification device (7) through the slag outlet (706), and are sent to the decomposition furnace (1) or the ash cooling and conveying system (12).

9. The method for coupling alternative fuel pyrolysis and gasification with a cement production line according to claim 8, characterized in that: Temperature control of the middle part (708) of the pyrolysis gasification device: when the temperature there is too high, the feed amount of hot raw material is increased, and the temperature in the incinerator is controlled by the decomposition and absorption of heat by the hot raw material; when the temperature there is too low, the air supply of the air distribution system is increased; the air supply fan (8) of the air distribution system is connected to the inlet of air or oxygen-rich gas, and the oxygen in the generated fluidizing air undergoes an oxidation reaction with the alternative fuel to generate heat to ensure the pyrolysis gasification temperature of the middle part (708) of the pyrolysis gasification device, so that its temperature is always at a suitable pyrolysis gasification temperature for various alternative fuels; Temperature control of the upper part of the pyrolysis gasification device (7): when the temperature there is too high, the amount of tertiary air fed in is reduced; when the temperature there is too low, the amount of tertiary air fed in is increased.

10. The method for coupling alternative fuel pyrolysis and gasification with a cement production line according to claim 8, characterized in that: Pressure control inside the pyrolysis gasification device (7): The flue gas access point of the pyrolysis gasification device (7) is connected to the upper position of the decomposition furnace (1), and the opening of the air volume regulating valve on the connecting pipeline between the flue gas outlet (711) of the pyrolysis gasification device (7) and the decomposition furnace (1) is adjusted, thereby controlling the wind speed and pressure of the flue gas entering the pyrolysis gasification device (7); or, adjusting the feed amount of the alternative fuel and the air supply amount of the blower (8), adjusting the gas production of the pyrolysis gasification reaction of the alternative fuel, thereby adjusting the internal pressure of the pyrolysis gasification device (7).

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