A garbage pyrolysis and gasification coupled blast furnace slag treatment process and system

Abstract

The present invention proposes a waste pyrolysis and gasification coupled blast furnace slag treatment process and system, which uses the waste heat of blast furnace slag as the heat source for waste pyrolysis and gasification reaction, recovers the heat of blast furnace slag in stages, uses high-grade heat for gasification reaction endothermicity, uses medium-grade heat for drying pyrolysis reaction endothermicity, and recovers low-grade heat through cold air for combustion in gas boilers, thus utilizing the heat of blast furnace slag in a cascade manner. Compared with the traditional slag flushing method using water, it improves energy utilization efficiency while solving the waste disposal problem. Compared with the traditional landfill or incineration method, treating waste by pyrolysis and gasification is more environmentally friendly, and the output gasification gas can be directly burned as a clean fuel or used as a chemical raw material for other chemical production.

Description

Technical Field

[0001] The invention relates to urban domestic waste treatment, and in particular to a waste pyrolysis and gasification coupled blast furnace slag treatment process and system. Background Art

[0002] Domestic waste treatment technologies include landfill, composting, and thermal treatment. Thermal treatment technologies can be divided into direct incineration and pyrolysis gasification. Pyrolysis gasification technology can convert urban domestic waste into three types of products with relatively stable components: gas, liquid, and solid for utilization, effectively improving its utilization efficiency, scope of utilization, and economy. From the perspective of pollutant emissions, secondary pollution caused by the insufficiency of direct incineration, especially the emission of dioxins, seriously restricts the promotion and application of this technology. The pyrolysis gasification process is carried out in an oxygen-poor or oxygen-deficient atmosphere, which in principle reduces the generation of dioxins. At the same time, most of the heavy metals will be dissolved into the ash during the pyrolysis gasification process, reducing the emission of heavy metals. However, the existing domestic waste pyrolysis gasification technology mainly adopts internal thermal pyrolysis gasification. Since a large amount of air will enter the furnace during the internal thermal pyrolysis gasification process, it is easy to produce dioxin pollution like waste incineration. At the same time, the N contained in the pyrolysis output gas 2 and CO 2 It accounts for a large proportion, which significantly reduces the calorific value of the gas and increases its utilization limitations. On the other hand, garbage pyrolysis and gasification is a strong endothermic reaction, especially since domestic garbage contains a large amount of water, and an external heat source is needed to heat, dry and pyrolyze the garbage. If coal is used for heating, secondary pollution is likely to occur; if electricity and gas are used for heating, the cost is relatively high.

[0003] my country's steel production has long been ranked first in the world, and is far ahead of other countries. At the same time, the amount of blast furnace slag rich in heat energy discharged from blast furnace smelting production is also huge. The temperature of slag out of the furnace is generally between 1400-1550℃. Each ton of slag contains about 1.74GJ of heat, which is equivalent to the calorific value of 60kg of standard coal. Recovering this part of sensible heat is of great significance for energy conservation and emission reduction. At present, 90% of blast furnace slag in my country is treated by water slag flushing. The traditional water slag flushing method has problems such as high water consumption, high pollution, unrecovered sensible heat, water slag needs to be dried, worn, and blocked. Dry sensible heat recovery technology is a technical route explored by the industry, mainly including wind quenching, rotary cup granulation and methane-steam reforming. Although various methods have made certain progress, they are actually insufficient in economy and relatively low in efficiency, and there are almost no industrial applications at present. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a waste pyrolysis and gasification coupled blast furnace slag treatment process and system to solve the problems of low waste utilization rate and high cost in the current pyrolysis and gasification technology and insufficient slag utilization rate.

[0005] To achieve the above purpose, the present invention intends to adopt the following technical means:

[0006] The present invention first proposes a waste pyrolysis and gasification coupled blast furnace slag treatment process, which couples the waste pyrolysis and gasification process with the blast furnace slag treatment process: the heat generated in the blast furnace slag treatment process is used to complete the waste drying, drying, and pyrolysis gasification process; at the same time, the gasification reaction of waste pyrolysis gas, semi-coke powder, and water vapor is completed along with the treatment of blast furnace slag;

[0007] The waste pyrolysis and gasification process includes five steps: drying, pyrolysis and gas production, pressure reduction and cooling.

[0008] The drying process is carried out under normal pressure. The heat source is the drying flue gas generated during the blast furnace slag treatment process, which directly contacts the garbage and evaporates the free water in the garbage.

[0009] The reaction pressure of the drying process is 1-2MPa, and the heat source is the medium-temperature gasification gas produced during the blast furnace slag treatment process, which separates the combined water in the garbage through indirect heat exchange;

[0010] The pressure of the pyrolysis gas production process is maintained at 1-2MPa. The heat source is the high-temperature gasification gas produced in the blast furnace slag treatment process. Through indirect heat exchange, the garbage is pyrolyzed to produce pyrolysis gas and residual semi-coke.

[0011] During the depressurization process, the pyrolysis gas generated in the pyrolysis gas production process is discharged, and the residual pyrolysis gas is further discharged by means of ejection for use in the blast furnace slag treatment process until it becomes a negative pressure state;

[0012] During the cooling process, the residual semi-coke is cooled by cold air and mixed with the residual pyrolysis gas before being discharged.

[0013] Furthermore, the drying flue gas temperature is 200-250°C; the heat source of the drying process is the medium-temperature gasification gas of 450-550°C; and the heat source of the pyrolysis gas production process is the high-temperature gasification gas of 800-1000°C.

[0014] Furthermore, the blast furnace slag treatment process is divided into a gasification stage, a drying stage, and a cooling stage;

[0015] The gasification section cools the slag from 1300-1500℃ to 800-1000℃. The released heat is used as the heat source for the pyrolysis gas production process. At the same time, the pyrolysis gas, water vapor and semi-coke powder generated in the pyrolysis gas production process enter the gasification section.

[0016] In the drying section, the slag is cooled from 800-1000℃ to 300-500℃ by the drying gas, and the released heat is used as the heat source for the drying process;

[0017] The cooling section reduces the slag temperature from 300-500℃ to 150-250℃, and the released heat is used to preheat the air for secondary utilization.

[0018] Further, the drying gas inlet temperature is 100-200°C and the outlet temperature is 450-550°C;

[0019] On this basis, the present invention also provides a garbage pyrolysis and gasification coupled blast furnace slag treatment system, including a gasifier and multiple dry pyrolysis reactors, the dry pyrolysis reactors are used to realize the above-mentioned five processes of garbage pyrolysis and gasification; the gasifier is used to treat blast furnace slag and simultaneously complete the gasification reaction of garbage pyrolysis gas, semi-coke powder and water vapor, and the dry pyrolysis reactor and the gasifier are connected by a number of pipelines.

[0020] Furthermore, the dry pyrolysis reactor comprises a shell, and also comprises a reaction chamber located in the shell, and a heat exchange tube is arranged on the inner wall of the shell;

[0021] A drying fume inlet and a fume outlet are respectively arranged at the lower and upper parts of the outer side of the shell. The drying fume enters the reaction chamber through the drying fume inlet to dry the substances in the reaction chamber and then is discharged through the fume outlet.

[0022] A medium-temperature gasification gas inlet, a drying output steam outlet and a low-temperature gasification gas outlet are respectively arranged at the lower and upper positions of the outer side of the shell. The medium-temperature gasification gas inlet is connected to the heat exchange pipe. The drying output steam outlet and the low-temperature gasification gas outlet are used to discharge water vapor and gasification gas respectively after drying the substances in the reaction chamber.

[0023] A high-temperature gasification gas inlet, a pyrolysis gas output gas outlet and a medium-temperature gasification gas outlet are respectively arranged at the lower and upper positions of the outer side of the shell. The high-temperature gasification gas inlet is connected to the heat exchange pipe. The pyrolysis gas output gas outlet and the medium-temperature gasification gas outlet are used to discharge the pyrolysis gas and the residual gasification gas after the pyrolysis gas generation of the material in the reaction chamber.

[0024] A pyrolysis gas ejection outlet is provided at the upper portion of the outer side of the shell to further discharge the residual pyrolysis gas until the pressure in the reactor is negative;

[0025] A normal temperature air inlet and a cooling air outlet are respectively provided at the lower and upper parts of the outer side of the shell, which are used to cool the residual semi-coke in the reactor and discharge the mixed gas.

[0026] Furthermore, the gasifier comprises a furnace body and a hopper at the bottom of the furnace body, wherein the hopper comprises a gasification section, a drying section and a cooling section from top to bottom;

[0027] The furnace body of the gasification section is provided with a water vapor semi-coke powder inlet, a pyrolysis gas inlet, and a high-temperature gasification gas outlet;

[0028] The furnace body of the drying section is provided with a drying gas inlet and a drying gas outlet, and a medium-temperature gasification gas outlet;

[0029] The furnace body of the cooling section is provided with a normal temperature air inlet, an air outlet and a drying fume outlet.

[0030] Preferably, part of the flue gas produced during the drying process of the drying pyrolysis reactor is deodorized by a deodorizing device and then discharged through a chimney, and the other part is sent to the drying section of the gasifier through a blower, and is heated again and then steam is produced through a heat exchanger.

[0031] The water vapor generated in the drying process of the drying pyrolysis reactor is decompressed and deodorized by a deodorizing device before being discharged through a chimney.

[0032] During the cooling process, cold air is sent into the dry pyrolysis reactor through a blower, mixed with the residual pyrolysis gas and sent to the gas boiler for combustion. The produced gasification gas is dust-removed and washed to become product fuel and sent to the gas storage cabinet.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] The process of the present invention uses the waste heat of blast furnace slag as the heat source for the pyrolysis and gasification reaction of garbage, and recovers the heat of blast furnace slag in stages. The high-grade heat is used for the heat absorption of gasification reaction, the medium-grade heat is used for the heat absorption of drying pyrolysis reaction, and the low-grade heat is recovered through cold air for combustion in gas boilers, thus utilizing the heat of blast furnace slag in stages. Compared with the traditional slag flushing method using water, the energy utilization efficiency is improved.

[0035] The system of the present invention uses pyrolysis and gasification to treat garbage, which is more environmentally friendly than traditional landfill or incineration methods. The output gasification gas can be directly burned as a clean fuel, or used as a chemical raw material for other chemical production. It can also solve the problem of insufficient slag utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a process system flow chart of the present invention.

[0037] Figure 2 Schematic diagram of the drying pyrolysis reactor.

[0038] The meanings of the symbols in the figure are as follows:

[0039] 1—drying pyrolysis reactor, 2—trolley, 3, 7—blower, 4, 9—dust collector, 5—gas washing, 6—gas storage cabinet, 8, 12, 17—locker, 10—burner, 11—gas boiler, 13—external steam, 14—blower, 15, 16—heat exchanger, 18—valve, 19—ejector, 20—gasifier, 21—semi-coke powder conveyor, 22—chimney, 23—cyclone dust collector, 24—deodorization device, 25—cooling gas main, 26—low-temperature flue gas main, 27—pyrolysis gas output gas main, 28—pyrolysis gas ejector main, 29—drying steam main, 30—low-temperature gasification gas main, 31—medium-temperature gasification gas main, 32—high-temperature gasification gas main, 33—drying flue gas main, 34—normal temperature air main.

[0040] 1-1—cooling air outlet, 1-2—drying flue gas outlet, 1-3—pyrolysis gas output gas outlet, 1-4—pyrolysis gas induced gas outlet, 1-5—drying output steam outlet, 1-6—low-temperature gasification gas outlet, 1-7—medium-temperature gasification gas outlet, 1-8—medium-temperature gasification gas inlet, 1-9—high-temperature gasification gas inlet, 1-10—drying flue gas inlet, 1-11—normal temperature air inlet.

[0041] The solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0042] The drying flue gas described in the present invention comes from the third stage of the gasification furnace, with a temperature of about 200° C. The flue gas directly contacts the garbage to evaporate the free water in the garbage.

[0043] The medium-temperature gasification gas of the present invention is the heat source in the drying process, with a temperature of about 500° C., which comes from the second stage of the gasification furnace. The gasification gas is cooled to about 300° C. and discharged.

[0044] The high-temperature gasification gas described in the present invention is produced by pyrolysis gasification process, and the heat source temperature is about 900°C, which comes from the first stage of the gasification furnace, where the garbage is heated to about 400°C, and the original garbage becomes pyrolysis gas and semi-coke.

[0045] It should be noted that the temperature values ​​of each link in the process are selected as the optimal temperature range. When the material ratios are different, the specific temperature may change. Adopting the process route of the present invention and selecting different temperatures also falls within the protection scope of this application.

[0046] The pyrolysis gasification described in the present invention is a reaction process, including five processes: drying, drying, pyrolysis gas production, pressure reduction and cooling. The pyrolysis gas production occurs in the third process, which means that the garbage undergoes pyrolysis reaction to generate pyrolysis gas. Pyrolysis gas is the general term for gas produced by pyrolysis reaction. Finally, the pyrolysis gas, residual semi-coke and water vapor generated by the drying and drying processes are coupled into the blast furnace slag treatment process.

[0047] Embodiment 1:

[0048] According to the above process, this embodiment provides a waste pyrolysis and gasification coupled blast furnace slag treatment process, which couples the waste pyrolysis and gasification and blast furnace slag treatment processes: the heat generated by the blast furnace slag treatment process is used to complete the waste drying, drying, and pyrolysis gasification processes; at the same time, the gasification reaction of waste pyrolysis gas, semi-coke powder, and water vapor is completed with the treatment of blast furnace slag;

[0049] The waste pyrolysis and gasification process includes five steps: drying, pyrolysis and gas production, pressure reduction and cooling.

[0050] The drying process is carried out under normal pressure. The heat source is the drying flue gas generated during the blast furnace slag treatment process, which directly contacts the garbage and evaporates the free water in the garbage.

[0051] The reaction pressure of the drying process is 1-2MPa, and the heat source is the medium-temperature gasification gas produced during the blast furnace slag treatment process, which separates the combined water in the garbage through indirect heat exchange;

[0052] The pressure of the pyrolysis gas production process is maintained at 1-2MPa. The heat source is the high-temperature gasification gas produced in the blast furnace slag treatment process. Through indirect heat exchange, the garbage is pyrolyzed to produce pyrolysis gas and residual semi-coke.

[0053] During the depressurization process, the pyrolysis gas generated in the pyrolysis gas production process is discharged, and the residual pyrolysis gas is further discharged by means of ejection for use in the blast furnace slag treatment process until it becomes a negative pressure state;

[0054] During the cooling process, the residual semi-coke is cooled by cold air and mixed with the residual pyrolysis gas before being discharged.

[0055] Furthermore, the drying flue gas temperature is 200-250°C; the heat source of the drying process is the medium-temperature gasification gas of 450-550°C; and the heat source of the pyrolysis gas production process is the high-temperature gasification gas of 800-1000°C.

[0056] Furthermore, the blast furnace slag treatment process is divided into a gasification stage, a drying stage, and a cooling stage;

[0057] The gasification section cools the slag from 1300-1500℃ to 800-1000℃. The released heat is used as the heat source for the pyrolysis gas production process. At the same time, the pyrolysis gas, water vapor and semi-coke powder generated in the pyrolysis gas production process enter the gasification section.

[0058] In the drying section, the slag is cooled from 800-1000℃ to 300-500℃ by the drying gas, and the released heat is used as the heat source for the drying process;

[0059] The cooling section reduces the slag temperature from 300-500℃ to 150-250℃, and the released heat is used to preheat the air for secondary utilization.

[0060] Further, the drying gas inlet temperature is 100-200°C and the outlet temperature is 450-550°C;

[0061] The main process route of the present invention is: the original garbage is sent to the drying pyrolysis reactor by a trolley, and is dried and pyrolyzed in the reactor. The original garbage is converted into pyrolysis gas and residual semi-coke. The pyrolysis gas is mainly composed of carbon monoxide, carbon dioxide, methane, and tar, and the semi-coke is mainly composed of fixed carbon and contains incombustibles in the original garbage. The pyrolysis gas enters the gasifier through a pipeline and undergoes a water vapor gasification reaction; the residual semi-coke is screened to remove incombustibles, and the fixed carbon is crushed to become semi-coke powder. The semi-coke powder is transported into the gasifier through steam, and the gasification reaction of pyrolysis gas, semi-coke powder, and water vapor is realized in the gasifier. The main components of the gas produced by the gasification reaction are hydrogen, carbon monoxide, water vapor, and carbon dioxide. The heat of the output gasified gas is used in each process link and then washed and sent to the gas storage tank, which can be directly used as a product fuel or a chemical raw material.

[0062] Embodiment 2:

[0063] The embodiment provides a garbage pyrolysis and gasification coupled blast furnace slag treatment system, which mainly uses two key devices: a drying pyrolysis reactor 1 and a gasifier 20. This embodiment further illustrates the system of the present invention.

[0064] The structure of the drying pyrolysis reactor 1 is as follows Figure 2As shown in the figure, the raw garbage in the reactor goes through five processes in sequence: drying, pyrolysis gas production, pressure reduction, and cooling: the drying process is basically carried out under normal pressure, and the flue gas enters the reactor from the drying flue gas inlet 1-10. The flue gas at about 200°C directly contacts the garbage, evaporates the free water in the garbage, and is discharged through the drying flue gas outlet 1-2. When the garbage is heated to 100°C, the separation of free water is basically completed and it enters the drying process; during the drying process, the heat source is the medium-temperature gasification gas of about 500°C produced, and the gasification gas The gas enters the reactor through the medium-temperature gasification gas inlet 1-8. The inner wall of the reactor is arranged with a serpentine heat exchange tube. The gasification gas heats the garbage to about 200°C by indirect heat exchange. During the process, the combined water in the garbage is separated, and the pressure in the reactor is adjusted to 1-2MPa. The produced water vapor is discharged through the dry output steam outlet 1-5. The gasification gas is cooled to about 300°C and discharged through the low-temperature gasification gas outlet 1-6. During the pyrolysis gas production process, the pressure in the reactor is maintained at 1-2MPa, and the heat source is the produced The high-temperature gasification gas of about 900℃ enters the reactor through the high-temperature gasification gas inlet 1-9. The inner wall of the reactor is arranged with a serpentine heat exchange tube. The gasification gas heats the garbage to about 400℃ through indirect heat exchange. In the process, the garbage is pyrolyzed to produce pyrolysis gas, which is discharged through the pyrolysis gas output gas outlet 1-3. The residual semi-coke remains in the car. The high-temperature gasification gas is cooled to about 500℃ and discharged through the medium-temperature gasification gas outlet 1-7. During the pressure reduction process, the pressure in the reactor is higher than the pressure in the gasifier. Open the valve The pressure is released, and the residual pyrolysis gas is discharged through the pyrolysis gas ejection gas outlet 1-4, and directly enters the gasifier after pressure reduction. When the pressure drops close to the pressure of the gasifier, the residual pyrolysis gas is further discharged by ejection using other pyrolysis gases discharged during the pyrolysis and gas production process, and the reactor becomes in a negative pressure state; finally, the cooling process is entered, and cold air enters the reactor through the normal temperature air inlet 1-11 to cool the residual semi-coke, and at the same time, it is mixed with the residual pyrolysis gas and discharged from the reactor through the cooling air outlet 1-1.

[0065] The gasifier 20 utilizes the heat of blast furnace slag to complete the gasification reaction of garbage pyrolysis gas, semi-coke powder and water vapor. The blast furnace slag falls freely through the top funnel and lands on the bottom rotor. The rotating rotor breaks the blast furnace slag into small droplets through impact and throws them into the air. The high-temperature slag droplets are cooled and solidified by the gasification gas in the air and then fall into the gasifier hopper. The gasifier consists of three sections. The first section is the gasification chamber. The slag at about 1400℃ is cooled to about 900℃. The heat released is used as the heat source for the gasification reaction. The pyrolysis gas enters the gasification chamber after decompression through the bypass valve 18 and the ejector 19. Water vapor and semi-coke powder are sent into the gasification chamber through the semi-coke powder conveyor 21. The second section is the drying section. The slag particles are cooled from about 900℃ to 400℃ by the drying gas. The heat released heats the drying gas. The inlet temperature of the drying gas is about 150℃ and is heated to about 500℃. The third section is the cooling section. The slag particles are discharged from the gasifier after being cooled from about 400℃ to 200℃. The heat released is used to preheat the air. The heated air enters the gas boiler. The three-stage gasifier and the outlet of the gasifier are equipped with a locker to intermittently discharge the blast furnace slag particles to ensure that the gas leakage between the three sections of the gasifier is limited.

[0066] The inlet and outlet pipes of the drying pyrolysis reactor 1 meet the needs of the five processes of drying, drying, pyrolysis gas production, pressure reduction and cooling in the process. In order to meet the needs of the drying pyrolysis reactor 1, a cooling gas main pipe 25, a low-temperature flue gas main pipe 26, a pyrolysis gas output gas main pipe 27, a pyrolysis gas ejector main pipe 28, a drying steam main pipe 29, a low-temperature gasification gas main pipe 30, a medium-temperature gasification gas main pipe 31, a high-temperature gasification gas main pipe 32, a drying flue gas main pipe 33, and a normal temperature air main pipe 34 are designed between the drying pyrolysis reactor 1 and the gasifier 20. It should be noted that changes made by increasing or decreasing the number of inlet and outlet pipelines of the reactor also fall within the scope of protection of this application.

[0067] The outlet main pipes of each pipeline of the reactor 1 adopt gas cylinders, and the gas distribution principle is the same as that of the present application, and also belongs to the protection scope of the present application.

[0068] The gas boiler 11 generates steam to drive the steam turbine to generate electricity, or directly uses the gas turbine to generate electricity, both of which are changes in the way the product gas is used. When the steam is insufficient, the external steam 13 is used, which also falls within the scope of protection of this application.

[0069] The semi-coke powder conveyor 21 uses water vapor as the conveying gas to convey the semi-coke powder. Using other types of gas to convey the semi-coke powder and then sending water vapor alone into the gasifier for gasification reaction also falls within the protection scope of this application.

[0070] The material lockers 8, 12, and 17 achieve the isolation of the material and the air space by discharging slag particles intermittently. Using other equipment with similar functions to achieve this function also falls within the scope of protection of this application.

[0071] The operation process of the system is as follows: the raw garbage is loaded into the trolley 2, and sent to the drying pyrolysis reactor 1 through the track. The above-mentioned five processes of drying, drying, pyrolysis gas production, pressure reduction, and cooling are completed in the reactor 1 in sequence. The flue gas produced during the drying process contains a large amount of water vapor, part of which is deodorized by the deodorizing device 24 and discharged through the chimney 22 for environmental protection, and part of which is sent to the second stage of the gasification furnace through the blower 14, and then heated again and steam is produced through the heat exchanger 16. The flue gas temperature is reduced to about 200°C and then used for garbage drying; the water vapor produced during the drying process is decompressed and deodorized by the deodorizing device 24 and then discharged through the chimney 22 for environmental protection; during the cooling process, the blower 3 sends cold air into the reactor 1, and after mixing with the residual pyrolysis gas, it is sent to the gas boiler for combustion together to reduce the dissipation loss of combustibles. The gasified gas produced passes through the dust collector 4 and the gas scrubber 5 to become the product fuel and is sent to the gas storage cabinet 6. Part of it is directly burned to generate electricity, and at the same time, the residual pyrolysis gas during the cooling process is consumed.

[0072] Effect demonstration:

[0073] According to the scheme of the present invention, aspn is used to simulate typical process parameters.

[0074] The industrial analysis of typical garbage components is 14.09% moisture content, 1.61% fixed carbon, 56.23% volatile matter, 28.07% ash, elemental analysis is 28.86% carbon, 3.04% hydrogen, 0.28% nitrogen, 0.12% sulfur, 39.63% oxygen, and the calorific value is 13.63Mj / kg.

[0075] The reaction conditions are as follows: in the first stage, the material is dried at a temperature of 100°C under normal pressure; in the second stage, the material is dried at a temperature of 200°C under 1MPa; in the pyrolysis process, the material is heated to 450°C under 2MPa; and in the gasification process, the material is heated to 950°C under normal pressure.

[0076] The main components of gasification output gas are water vapor 20.3%, hydrogen 37%, carbon monoxide 30.8%, carbon dioxide 11.6%. After cooling and purification, the low calorific value of the combustible product gas can reach 10MJ / Nm 3 above.

Claims

1. A garbage pyrolysis and gasification coupled blast furnace slag treatment process, characterized in that: The process couples the waste pyrolysis and gasification process with the blast furnace slag treatment process: the waste pyrolysis and gasification process is completed by utilizing the heat generated by the blast furnace slag treatment process; the waste pyrolysis and gasification process includes drying, drying, pyrolysis gas production, pressure reduction and cooling in sequence; Drying is carried out under normal pressure. The heat source is the drying flue gas generated during the treatment of blast furnace slag, which comes into direct contact with the garbage to evaporate the free water in the garbage. The drying reaction pressure is 1-2MPa, and the heat source is the medium-temperature gasification gas produced during the treatment of blast furnace slag, which separates the combined water in the garbage through indirect heat exchange; The pyrolysis gas production pressure is maintained at 1-2MPa. The heat source is the high-temperature gasification gas produced during the blast furnace slag treatment process. Through indirect heat exchange, the garbage undergoes pyrolysis reaction to generate pyrolysis gas and residual semi-coke. When the pressure is reduced, the pyrolysis gas generated in the pyrolysis gas production process is discharged, and the residual pyrolysis gas is further discharged by injection for use in the blast furnace slag treatment process until it becomes a negative pressure state; During the cooling process, the residual semi-coke is cooled by cold air and mixed with the residual pyrolysis gas before being discharged; Finally, the pyrolysis gas, residual semi-coke and water vapor generated in the drying and drying process are coupled into the blast furnace slag treatment process.

2. The garbage pyrolysis and gasification coupled blast furnace slag treatment process as claimed in claim 1, characterized in that: The drying flue gas temperature is 200-250℃; The heat source for the drying process is medium temperature gasification gas at 450-550°C; The heat source of the pyrolysis gas production process is 800-1000℃ high temperature gasification gas.

3. The waste pyrolysis and gasification coupled blast furnace slag treatment process as claimed in claim 1, characterized in that: The blast furnace slag treatment process is divided into gasification section, drying section and cooling section; The gasification section cools the slag from 1300-1500℃ to 800-1000℃. The released heat is used as the heat source for the pyrolysis gas production process. At the same time, the pyrolysis gas, water vapor and semi-coke powder generated in the pyrolysis gas production process enter the gasification section. In the drying section, the slag is cooled from 800-1000℃ to 300-500℃ by the drying gas, and the released heat is used as the heat source for the drying process; The cooling section reduces the slag temperature from 300-500℃ to 150-250℃, and the released heat is used to preheat the air for secondary utilization.

4. The waste pyrolysis and gasification coupled blast furnace slag treatment process as claimed in claim 3 is characterized in that: The drying gas inlet temperature is 100-200℃ and the outlet temperature is 450-550℃.

5. A garbage pyrolysis and gasification coupled blast furnace slag treatment system, characterized in that: It comprises a gasifier and a plurality of drying pyrolysis reactors, wherein the drying pyrolysis reactors are used to realize the five processes of pyrolysis and gasification of garbage in the treatment process described in claim 1; the gasifier is used to process blast furnace slag and simultaneously complete the gasification reaction of pyrolysis gas, semi-coke powder and water vapor of garbage, and the drying pyrolysis reactors and the gasifier are connected by a plurality of pipelines; The dry pyrolysis reactor comprises a shell and a reaction chamber located in the shell, and a heat exchange tube is arranged on the inner wall of the shell; A drying fume inlet and a fume outlet are respectively arranged at the lower and upper parts of the outer side of the shell. The drying fume enters the reaction chamber through the drying fume inlet to dry the substances in the reaction chamber and then is discharged through the fume outlet. A medium-temperature gasification gas inlet, a drying output steam outlet and a low-temperature gasification gas outlet are respectively arranged at the lower and upper positions of the outer side of the shell. The medium-temperature gasification gas inlet is connected to the heat exchange pipe. The drying output steam outlet and the low-temperature gasification gas outlet are used to discharge water vapor and gasification gas respectively after drying the substances in the reaction chamber. A high-temperature gasification gas inlet, a pyrolysis gas output gas outlet and a medium-temperature gasification gas outlet are respectively arranged at the lower and upper positions of the outer side of the shell. The high-temperature gasification gas inlet is connected to the heat exchange pipe. The pyrolysis gas output gas outlet and the medium-temperature gasification gas outlet are used to discharge pyrolysis steam and residual gasification gas respectively after the substances in the reaction chamber are pyrolyzed and gasified. A pyrolysis gas ejection outlet is provided at the upper portion of the outer side of the shell to further discharge the residual pyrolysis gas until the pressure in the reactor is negative; A normal temperature air inlet and a cooling air outlet are respectively provided at the lower and upper parts of the outer side of the shell, for cooling the residual semi-coke in the reactor and discharging the mixed gas; The gasifier comprises a furnace body and a hopper at the bottom of the furnace body, wherein the hopper comprises a gasification section, a drying section and a cooling section from top to bottom; The furnace body of the gasification section is provided with a steam semi-coke powder inlet, a pyrolysis gas inlet, and a high-temperature gasification gas outlet; The furnace body of the drying section is provided with a drying gas inlet and a drying gas outlet, and a medium-temperature gasification gas outlet; The furnace body of the cooling section is provided with a normal temperature air inlet, an air outlet, and a drying fume outlet; The flue gas produced during the drying process of the drying pyrolysis reactor is partially deodorized by the deodorization device and then discharged through the chimney, and the other part is sent to the drying section of the gasifier through a blower, and then heated again and steam is produced through a heat exchanger; The water vapor generated in the drying process of the drying pyrolysis reactor is decompressed and deodorized by a deodorizing device before being discharged through a chimney.

6. The garbage pyrolysis and gasification coupled blast furnace slag treatment system as claimed in claim 5, characterized in that: During the cooling process, cold air is sent into the dry pyrolysis reactor through a blower, mixed with the residual pyrolysis gas and sent to the gas boiler for combustion. The produced gasification gas is dust-removed and washed to become product fuel and sent to the gas storage cabinet.

Images