A moving bed solid waste segmented pyrolysis gasification process and system

Abstract

The present invention discloses a moving bed solid waste segmented pyrolysis gasification process and system, which solves the problems of the existing solid waste pyrolysis gasification technology process system being complex, having a high failure rate, low efficiency, high energy consumption, poor environmental protection, and high investment and operating costs. The technical scheme includes the following steps: (1) solid waste is sent to a pyrolysis system for pyrolysis to obtain pyrolysis gas and pyrolysis residue; (2) the pyrolysis gas is sent to an organic matter gasification and decomposition system for heating and gasification to remove tar, dioxins and other macromolecular organic matter, and then synthesis gas is obtained after heat recovery, washing, dust removal and deacidification; (3) the pyrolysis residue is cooled and sorted to obtain combustible carbon slag and residual residue. The present invention has a simple system, reliable process, simple operation, high energy conversion efficiency, good resource utilization effect, energy saving and consumption reduction, low investment and operating costs, and is environmentally friendly.

Description

Technical Field

[0001] The invention relates to a solid waste treatment process and system, in particular to a moving bed solid waste segmented pyrolysis and gasification process and system. Background Art

[0002] At present, there are three main ways to deal with solid waste (urban garbage, industrial garbage, medical waste, other toxic and hazardous waste, etc.), namely sanitary landfill, composting and incineration power generation. The treatment principles followed are harmlessness, reduction and resource utilization. Undoubtedly, among the three treatment methods, the incineration power generation method has a more prominent advantage. It can not only reduce land occupation, achieve solid waste reduction and generate electricity at the same time, and create certain economic benefits, but the incineration method also brings some problems: ① Due to the low incineration temperature, it is easy to produce carcinogens such as dioxins and furans; ② The fly ash and residues produced by incineration are rich in toxic and harmful heavy metal substances, which are easy to cause groundwater pollution; ③ Incineration produces a large amount of flue gas and large carbon emissions; In addition, due to the planning and construction of incineration power plants, mass incidents caused by the "NIMBY effect" caused by the planning and construction of incineration power plants occur from time to time. Therefore, researching and developing a new green and environmentally friendly technology for solid waste treatment to minimize and eliminate the environmental pollution problems caused by its treatment process has become a new research topic in the current solid waste treatment field.

[0003] Solid waste gasification technology and pyrolysis technology are new solid waste treatment technologies developed in recent years. After nearly three decades of research and development, solid waste gasification technology represented by plasma gasification technology and thermal separation gasification technology has achieved certain results. At present, these two technologies have been applied and promoted to a certain extent abroad, but they are not widely used. There are mainly the following problems: ① The gasification reaction temperature is high, which is used to ensure that all components in the solid waste are melted and gasified, resulting in high energy consumption; ② The process system is relatively complex. Plasma gasification technology requires a special plasma torch system, and thermal separation gasification technology also requires a special fuel gas auxiliary system; ③ Due to the high reaction temperature, the system operation is relatively complex, the reliability is poor, and the operation and maintenance costs are high; ④ Due to the micro-positive pressure of the gasification pressure, the processing capacity is generally low. The maximum capacity of a single furnace currently in industrial application is 360t / d; ⑤ The investment is high and the project economy is poor. However, the existing solid waste pyrolysis technology is not yet mature enough, and there are still many problems that need to be studied and solved, so there are few reports on related industrial applications. By consulting the existing literature and analyzing the data, CN2447644Y discloses "a vertical converter type domestic waste pyrolysis gasification incinerator", which has the disadvantages of unstable operating conditions, high failure rate, incomplete combustion, etc.; CN2811769Y discloses "a solid waste pyrolysis gasification incinerator", which adopts the method of grate pyrolysis incineration plus secondary combustion chamber, and focuses more on incineration; CN204388069U discloses "a solid waste pyrolysis melting gasification treatment device", which adopts the melting incineration method of reciprocating grate furnace structure, and is equipped with a waste gas conversion device, which also focuses on the step-by-step incineration of solid waste. Pyrolysis and incineration; CN202203950U discloses "an organic solid waste pyrolysis and gasification device", which mainly adopts a rotary kiln pyrolysis furnace with a heat carrier and a fluidized bed combustion chamber. The process system is complex and has a high failure rate; CN104910930A discloses "organic solid waste pyrolysis treatment device, system and method", which adopts a horizontal rotary kiln structure similar to a rotary kiln structure, with multiple sleeve structures, mainly for low-temperature pyrolysis of organic solid waste to obtain gas, liquid and solid three-phase products, but no inventions have been made for the separation and purification process of the three-phase products, and the process system is complex and not very feasible. After further analysis, it can be seen that the current solid waste pyrolysis technology cannot effectively separate and process the gas and liquid products of pyrolysis, and often uses a two-combustion chamber structure to burn the gas and liquid two-phase products at the outlet of the pyrolysis furnace, which reduces the energy utilization efficiency of pyrolysis. Summary of the invention

[0004] The purpose of the present invention is to solve the above technical problems and to provide a moving bed solid waste segmented pyrolysis gasification process which has simple process, easy operation, high energy conversion efficiency, good resource utilization effect, energy saving and consumption reduction, and is environmentally friendly.

[0005] The present invention also provides a system for the above process, which has the advantages of simple system, low energy consumption, low equipment investment and operation cost, continuous production and reduced labor intensity.

[0006] The present invention discloses a moving bed solid waste segmented pyrolysis gasification process, comprising the following steps: (1) feeding solid waste into a pyrolysis system for pyrolysis to obtain pyrolysis gas and pyrolysis residue; (2) feeding the pyrolysis gas into an organic matter gasification decomposition system for heating and gasification to remove tar, dioxins and other macromolecular organic matter, and then obtaining synthesis gas after heat recovery, washing and deacidification; and (3) cooling and sorting the pyrolysis residue to obtain combustible carbon slag and residual residue.

[0007] In the step (1), the pyrolysis system includes a lock hopper, a pyrolysis furnace, and a hot air furnace for supplying heat to the pyrolysis furnace. The pyrolysis furnace is a moving bed pyrolysis furnace having a vertical cylindrical sleeve structure, and is composed of an upper pyrolysis section and a lower cooling section. Solid waste is fed into the pyrolysis furnace through the lock hopper, and the pyrolysis temperature in the pyrolysis furnace is controlled to be 550 to 650° C. The operating pressure in the furnace is controlled to be -3 kPaG to -0.1 kPaG. The residence time of the solid waste in the pyrolysis section is 10 to 90 minutes, and the pyrolysis residue discharged from the cooling section is cooled to 250 to 350° C.

[0008] In the step (1), the pyrolysis section is provided with a heat exchange jacket, and the cooling section is also provided with a cooling jacket, and both the heat exchange jacket and the cooling jacket are provided with heat exchange fins; the high-temperature flue gas of the hot blast furnace is fed into the heat exchange jacket, and part of the flue gas exiting the heat exchange jacket is fed into the hot blast furnace as temperature-adjusting flue gas for temperature adjustment, and the rest of the flue gas is used to remove waste heat and is utilized by the system, so that the temperature of the high-temperature flue gas exiting the hot blast furnace is controlled to be 800-1000°C.

[0009] In the step (1), air first enters the cooling jacket for preheating and then is sent to the hot air furnace as combustion air. The air is preferably odor from a solid waste storage pit.

[0010] The organic matter gasification and decomposition system comprises an organic matter decomposition gasifier and a pyrolysis gas retention buffer tank. The pyrolysis gas is first heated to 1050-1100° C. by the organic matter decomposition gasifier, and then sent to the pyrolysis gas retention buffer tank to fully decompose the tar, dioxins and other macromolecular organic matter carried in the pyrolysis gas. The residence time of the pyrolysis gas in the pyrolysis gas retention buffer tank is controlled to be 10-20s, and the temperature of the synthesis gas leaving the pyrolysis gas retention buffer tank is 1000-1050° C.

[0011] In step (2), the organic matter decomposition gasifier is a cyclone separator structure. The pyrolysis gas enters from the middle of the organic matter decomposition gasifier and spirally rises. Under the action of the combustion nozzle, it reacts and heats up, so that the tar, dioxins and other macromolecular organic matter carried in the pyrolysis gas are gasified and decomposed, and the ash carried in the pyrolysis gas is discharged from the bottom outlet of the organic matter decomposition gasifier.

[0012] In the step (2), the synthesis gas from the pyrolysis gas retention buffer tank is cooled to 180-250°C by a heat recovery system to recover heat, and then washed and deacidified by a synthesis gas washing, dust removal and deacidification system to further reduce the temperature to 30-50°C, and then drawn into the downstream purification process for further treatment by a synthesis gas induced draft fan.

[0013] In the step (3), the pyrolysis residue and the ash produced by the organic matter gasification decomposition system are first cooled to 40-90° C. in a pyrolysis residue cooler, and then sent to a pyrolysis residue sorting system for sorting to obtain combustible carbon slag and residual residue. The combustible carbon slag is sent to a hot blast furnace for combustion as fuel, and the insufficient part is introduced into the synthesis gas obtained in step (2) or supplemented by other external fuels.

[0014] The present invention discloses a moving bed solid waste segmented pyrolysis and gasification system for the above-mentioned process, comprising a pyrolysis system, an organic matter gasification and decomposition system, a heat recovery system, and a synthesis gas washing, dust removal and deacidification system which are connected in sequence. The pyrolysis system comprises a lock hopper, a pyrolysis furnace, and a hot air furnace for supplying heat to the pyrolysis furnace. The pyrolysis gas outlet of the upper section of the pyrolysis furnace is connected to the organic matter gasification and decomposition system, and the bottom outlet of the pyrolysis furnace is connected to the fuel inlet of the hot air furnace via a pyrolysis residue cooler and a pyrolysis residue sorting system.

[0015] The pyrolysis furnace is a moving bed pyrolysis furnace having a vertical cylindrical sleeve structure, and is composed of an upper pyrolysis section and a lower cooling section. The pyrolysis section is provided with a heat exchange jacket, and the cooling section is provided with a cooling jacket. Heat exchange fins are provided in the heat exchange jacket and the cooling jacket.

[0016] The flue gas outlet of the hot blast stove is connected to the flue gas inlet of the heat exchange jacket, the flue gas outlet of the heat exchange jacket is connected to the temperature-adjusting flue gas inlet of the hot blast stove, and the outlet of the synthesis gas washing, dust removal and deacidification system is also connected to the fuel inlet of the hot blast stove.

[0017] The cooling jacket has an air inlet and an air outlet, wherein the air inlet is connected to the air blower outlet, and the air outlet is connected to the air inlet of the hot air furnace.

[0018] The organic matter decomposition gasifier has a structure similar to that of a cyclone separator, with 1-3 combustion nozzles arranged on the upper part. The middle inlet of the organic matter decomposition gasifier is connected to the pyrolysis furnace, the top outlet is connected to the pyrolysis gas retention buffer tank, and the bottom outlet is connected to the pyrolysis residue cooler.

[0019] The bottom outlet of the organic matter decomposition gasifier of the pyrolysis furnace is connected to the pyrolysis residue cooler.

[0020] The connecting pipeline between the pyrolysis furnace and the organic matter decomposition gasifier has an upward inclination angle, and the angle is controlled at 30 to 60 degrees.

[0021] In view of the problems existing in the background technology, the inventors have made the following improvements:

[0022] An organic matter gasification decomposition system is set up to fully decompose the tar and dioxin and other macromolecular organic matter carried in the pyrolysis gas. Since the solid waste itself generally carries a certain amount of dioxin, and the pyrolysis temperature is generally below 850°C (the present invention is medium-temperature pyrolysis, and the pyrolysis temperature is 550-650°C), dioxin will inevitably be produced during the pyrolysis process, and medium-temperature pyrolysis will also produce tar and other macromolecular organic matter. The decomposition temperature of such organic matter is generally above 900°C, and sufficient residence time is required to be completely decomposed. Dioxin needs to be above 850°C and the residence time is more than 2s to be completely destroyed and decomposed, and tar needs to be above 1000°C and the residence time is 10s to be completely decomposed. The organic matter gasification and decomposition system includes an organic matter decomposition gasifier and a pyrolysis gas retention buffer tank. By setting up the organic matter decomposition gasifier, fuel and combustion-supporting oxygen are sprayed into the ground through the fuel nozzle to burn and heat the pyrolysis gas, providing a reaction temperature for the decomposition of tar and dioxins. Then, the pyrolysis gas retention buffer tank is used to ensure that the pyrolysis gas after heating has a sufficient residence time, thereby ensuring that the tar and dioxins are fully decomposed. At the same time, under the action of the water vapor carried in the pyrolysis gas, a water gasification reaction occurs to generate a synthesis gas mainly composed of H2 and CO, thereby further increasing the yield of the synthesis gas. It can also effectively avoid the blockage problem of subsequent equipment and pipeline systems caused by the tar in the pyrolysis gas in conventional pyrolysis technology. The wastewater from the subsequent synthesis gas washing also does not contain pollutants such as tar, naphthalene, and phenol, which can reduce the difficulty of subsequent wastewater treatment. The wastewater treatment is simple and easy to meet the discharge standards.

[0023] The fuel gas and (unclear expressions such as a small amount, an appropriate amount, etc. are avoided as much as possible) pure oxygen are injected into the organic matter decomposition gasifier. The temperature of the pyrolysis gas is controlled at 1050-1000°C by controlling the amount of oxygen injected. The residence time of the pyrolysis gas in the pyrolysis gas retention buffer tank is controlled at 10-20s, and the temperature of the synthesis gas out of the pyrolysis gas retention buffer tank is controlled at 1000-1050°C, thereby ensuring that the tar and dioxins are completely decomposed and gasified. The oxygen volume concentration is preferably controlled at ≥95%.

[0024] After being discharged from the bottom of the pyrolysis gas retention buffer tank, the synthesis gas enters the heat recovery system to recover most of the high-temperature sensible heat in the synthesis gas and produce steam as a by-product. The synthesis gas is then sent to the synthesis gas washing, dust removal and deacidification system for washing, cooling, dust removal and deacidification. Finally, it is drawn to the downstream process for further purification through the synthesis gas induced draft fan. The obtained synthesis gas can also be partially returned to the hot air furnace as a fuel for combustion. The synthesis gas washing, dust removal and deacidification system can be supplemented with alkaline solution as needed to remove acid gases such as HCl and HF.

[0025] For the pyrolysis residue discharged from the bottom of the pyrolysis furnace and the ash produced at the bottom of the organic matter decomposition gasifier, the inventor no longer adopts the method of simply burning or landfilling them, but first cools them through the pyrolysis residue cooler, controls the temperature of the residue entering the pyrolysis residue sorting system at 40-90°C, and then sends them to the pyrolysis residue sorting system for sorting. The sorted combustible carbon slag is sent to the hot blast furnace as the main fuel for combustion, and the remaining residue is further used in the comprehensive utilization system. The above method greatly improves the comprehensive utilization efficiency of energy from pyrolysis and gasification of solid waste on the one hand, and further eliminates and avoids the generation and diffusion transfer of dioxins in the ash on the other hand. This is because the pyrolysis temperature is lower than the combustion and gasification temperature. After the solid waste is pyrolyzed, there is still a considerable amount of combustible material mixed in the ash that cannot be completely pyrolyzed and reacted. This part of the unreacted combustible material is sorted out and burned at high temperature in the hot blast furnace (the temperature can reach above 1000℃). This part of energy can be fully utilized to provide heat for pyrolysis, thereby achieving effective energy recovery and reducing pollution and emissions. The insufficient part can be introduced into the produced synthesis gas or supplemented by external fuel, so as to achieve self-sufficiency of system energy. At the same time, because the residual carbon in the ash can be further destroyed and decomposed after high-temperature combustion, the dioxins that may be carried in it can be eliminated and avoided. The generation and diffusion transfer of dioxins in the ash.

[0026] A cooling section is provided at the lower section of the pyrolysis furnace. A cooling medium can be introduced into the cooling jacket of the cooling section to indirectly heat exchange and cool the pyrolysis residue entering the cooling section. The cooling medium can be cooling water or air. Preferably, the combustion-supporting air entering the hot blast furnace is introduced into the cooling jacket of the cooling section as a cooling medium to cool the pyrolysis residue. The combustion-supporting air is sent to the hot blast furnace after preheating, which can further reduce energy consumption and reduce the temperature of the pyrolysis residue out of the furnace. Preferably, the combustion-supporting air preferably uses the odor extracted from the solid waste storage pit. After the odor is burned at high temperature in the hot blast furnace, the spread of the odor can be effectively avoided, which is environmentally friendly; the high-temperature hot flue gas produced by the hot blast furnace is first mixed with the medium-temperature flue gas out of the heat exchange jacket in the hot blast furnace for temperature adjustment, and then sent to the pyrolysis section of the pyrolysis furnace as a pyrolysis heat source.

[0027] The connecting pipe between the pyrolysis furnace and the organic matter decomposition gasifier should be as short as possible, and its upward inclination angle should be controlled at 30-60 degrees, so that when the working conditions fluctuate, large molecular organic matter such as tar can be smoothly condensed and refluxed into the pyrolysis furnace for further pyrolysis.

[0028] The specific beneficial effects of the present invention are summarized as follows:

[0029] 1. The solid waste staged pyrolysis gasification technology is adopted. The solid waste is first pyrolyzed to produce pyrolysis gas. The pyrolysis gas is then decomposed by an organic matter decomposition gasifier to decompose the tar, dioxins and other macromolecular organic matter carried therein. The halogen elements such as HCl and HF are removed by alkaline washing, which can effectively prevent the re-generation of dioxins and ensure that the synthesis gas does not contain dioxins, thereby effectively solving the problem of dioxins easily produced by incineration technology.

[0030] 2. The ash produced after the staged pyrolysis and gasification of solid waste is sorted and recycled to the hot blast furnace as combustible carbon solid fuel for combustion and provides heat for the pyrolysis furnace. This not only greatly improves the comprehensive energy utilization efficiency of the pyrolysis and gasification of solid waste, but also has high resource recycling efficiency, and further eliminates and avoids the generation and diffusion transfer of dioxins in the ash.

[0031] 3. By setting up an organic matter decomposition gasifier and a pyrolysis gas retention buffer tank to fully decompose the tar, naphthalene, phenol and other organic matter carried in the pyrolysis gas, the blockage problem of subsequent equipment and pipeline systems caused by tar in the pyrolysis gas in conventional pyrolysis technology can be effectively avoided. At the same time, since the wastewater does not contain pollutants such as tar, naphthalene, phenol, etc., the difficulty of subsequent wastewater treatment can be reduced, and the wastewater treatment is simple and easy to meet the discharge standards.

[0032] 4. The synthesis gas produced by staged pyrolysis and gasification of solid waste can not only be further used for combustion to generate electricity, but also can be used to produce chemical products such as natural gas, methanol, synthetic ammonia and urea. There are many product solutions for resource utilization, and the process is simple, the resource utilization effect is good, and it is easy to promote and apply.

[0033] 5. The moving bed pyrolysis technology is used in conjunction with the hot blast furnace to burn the ash. By selecting a suitable feeding system, the feeding is not limited by the particle size of the solid waste, and it is easy to achieve the simultaneous feeding of solid wastes of different sizes, and the raw material adaptability is wider.

[0034] 6. The combustion air of the hot blast furnace can be the odor extracted from the solid waste storage pit, which can effectively avoid the spread of odor.

[0035] 7. The pyrolysis furnace and organic matter decomposition gasifier of the present invention have simple structures, no supporting or transmission parts in the furnace, less maintenance, low operating cost, and can effectively ensure the long-term operation of the equipment.

[0036] 8. The nominal capacity of a single pyrolysis furnace for treating solid waste is 50-500t / d. It is suitable for both centralized treatment of large-scale solid waste and flexible treatment of small-scale solid waste, and has a wide range of applications.

[0037] 9. The system is simple, compact, energy-efficient, low in investment and operating costs, safe and reliable, energy-saving and environmentally friendly. It can simultaneously process solid wastes such as domestic garbage and organic sludge, realize comprehensive disposal of regional solid wastes, and produce clean fuels. It can be widely promoted as a distributed energy station in counties, towns, rural areas and industrial parks, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a process flow chart and system diagram of the method of the present invention;

[0039] Among them: 1-lock hopper; 2-pyrolysis furnace, 2.1-pyrolysis section, 2.11-heat exchange jacket, 2.2-cooling section, 2.21-cooling jacket, 2.3-heat exchange fins; 3-organic matter decomposition gasifier, 3.1-combustion nozzle; 4-pyrolysis gas retention buffer tank; 5-heat recovery system; 6-synthesis gas washing, dust removal and deacidification system; 7-synthesis gas induced draft fan; 8-pyrolysis residue cooler; 9-pyrolysis residue sorting system; 10-hot air furnace; 11-air fan; 12-flue gas fan. DETAILED DESCRIPTION

[0040] The system of the present invention is further explained below in conjunction with the accompanying drawings.

[0041] Reference Figure 1 The present invention includes a pyrolysis system, an organic matter gasification and decomposition system, a heat recovery system 5, and a synthesis gas washing, dust removal and deacidification system. The pyrolysis system includes a lock hopper 1, a pyrolysis furnace 2, and a hot air furnace 10 for supplying heat to the pyrolysis furnace 2; the organic matter gasification and decomposition system includes an organic matter decomposition gasifier 3 and a pyrolysis gas retention buffer tank 4. The lock hopper 1 is connected to the material inlet of the pyrolysis furnace 2, and the pyrolysis gas outlet of the upper section of the pyrolysis furnace 2 is connected through the organic matter decomposition gasifier 3, the pyrolysis gas retention buffer tank 4, the heat recovery system 5, the synthesis gas washing, dust removal and deacidification system 6 and the synthesis gas induced draft fan 7. The bottom outlet of the pyrolysis furnace 1 is connected to the fuel inlet of the hot air furnace 10 through a pyrolysis residue cooler 8 and a pyrolysis residue sorting system 9.

[0042] The pyrolysis furnace 2 is a moving bed pyrolysis furnace, having a vertical cylindrical sleeve structure, and is composed of an upper pyrolysis section 2.1 and a lower cooling section 2.2. The pyrolysis section 2.1 is provided with a heat exchange jacket 2.11, and the cooling section 2.2 is provided with a cooling jacket 2.21. Heat exchange fins 2.3 are provided in the heat exchange jacket 2.11 and the cooling jacket 2.21. The connecting pipe between the pyrolysis furnace 2 and the organic matter decomposition gasifier 3 has an upward inclination angle a, and the angle is controlled at 30 to 60 degrees.

[0043] The smoke outlet of the hot blast stove 10 is connected to the smoke inlet of the heat exchange jacket 2.11, and the smoke outlet of the heat exchange jacket 2.11 is connected to the temperature-adjusting smoke inlet of the hot blast stove 10 via the smoke fan 12.

[0044] The cooling jacket 2 . 21 has an air inlet and an air outlet. The air inlet is connected to the outlet of the air blower 11 , and the air outlet is connected to the air inlet of the hot air furnace 10 .

[0045] The organic matter decomposition gasifier has a structure similar to that of a cyclone separator, with 1-3 combustion nozzles arranged on the upper part. The middle inlet of the organic matter decomposition gasifier is connected to the pyrolysis furnace, the top outlet is connected to the pyrolysis gas retention buffer tank, and the bottom outlet is connected to the pyrolysis residue cooler.

[0046] Process and method:

[0047] See also Figure 1 After the raw solid waste is crushed into a particle size of 5 to 150 mm, it is sent to the lock hopper 1 through the feeding device, and then sent to the pyrolysis furnace 2 through the material inlet for pyrolysis. The pyrolysis temperature in the pyrolysis furnace 2 is controlled to be 550 to 650°C. The solid waste stays in the pyrolysis section 2.1 for 10 to 90 minutes. The heat exchange jacket 2.11 introduces high-temperature flue gas from the hot blast stove 10 to provide heat for the pyrolysis section 2.1, so that the solid waste is pyrolyzed to produce pyrolysis gas and pyrolysis residue. The pyrolysis gas temperature out of the pyrolysis furnace 2 is controlled at 300 to 350°C. The pyrolysis gas is sent to the organic matter decomposition gasifier 3 through the pyrolysis gas outlet of the pyrolysis furnace 2 for further gasification and temperature increase. The pyrolysis gas enters from the middle of the organic matter decomposition gasifier 3 and then spirally rises. The fuel and oxygen (oxygen volume concentration is controlled at ≥95%) injection amount is controlled by the upper combustion nozzle 3.1 to control the pyrolysis gas temperature to 1050 to 1100°C. The tar, dioxins and other macromolecular organics carried in the pyrolysis gas are gasified and decomposed, while the ash carried in the pyrolysis gas is discharged from the bottom outlet of the organic matter decomposition gasifier 3. The pyrolysis gas is directly sent to the pyrolysis gas retention buffer tank 4 through the top outlet to fully decompose the tar, dioxins and other macromolecular organics carried in the pyrolysis gas. The residence time of the pyrolysis gas in the pyrolysis gas retention buffer tank 4 is controlled to be 10-20s, and the temperature of the synthesis gas out of the pyrolysis gas retention buffer tank 4 is 1000-1050°C, so as to ensure that the tar, dioxins and other macromolecular organics in the synthesis gas are completely decomposed and gasified. After most of the heat in the synthesis gas is recovered by the heat recovery system 5 and the by-product steam is produced, the temperature of the synthesis gas is reduced to 180-250°C. After washing, dust removal and deacidification by the synthesis gas washing, dust removal and deacidification system 6, the temperature of the synthesis gas is further reduced to 30-50°C, and finally drawn by the synthesis gas induced draft fan 7 to the downstream purification process for further treatment. Among them, the synthesis gas washing, dust removal and acid removal system 6 adds an appropriate amount of alkaline solution as needed to remove acid gases such as HCl and HF; the synthesis gas induced draft fan 7 is used to extract the synthesis gas and control the pyrolysis furnace 2 to operate under a slightly negative pressure. The operating pressure in the furnace is controlled at -3kPaG to -0.1kPaG, and the synthesis gas pressure at the induced draft fan outlet is controlled at 3kPaG to 10kPaG.

[0048] The pyrolysis residue produced by the pyrolysis furnace 2 first falls into the cooling section 2.2 at the bottom of the pyrolysis furnace and is pre-cooled by indirect heat exchange with the air in the cooling jacket 2.21, and the pyrolysis residue is cooled to 250-350°C, and then discharged from the bottom outlet of the pyrolysis furnace 2, and the residence time of the solid waste in the pyrolysis furnace 2 is controlled to be 10-90 minutes. The pyrolysis residue discharged from the bottom of the pyrolysis furnace 2 and the ash discharged from the bottom outlet of the organic matter decomposition gasifier 3 are cooled together through the pyrolysis residue cooler 8, and the temperature of the cooled pyrolysis residue is controlled to be 40-90°C, and then enters the pyrolysis residue sorting system 9 for sorting, thereby obtaining combustible carbon residue and residual residue, wherein the combustible carbon residue is sent to the hot blast furnace 10 through the fuel inlet to be burned to obtain high-temperature hot flue gas, which provides heat for the pyrolysis section 2.1 of the pyrolysis furnace 2, and the residual residue is sent to further processes for comprehensive utilization. The cooling medium introduced into the cooling jacket 2.21 can be air, cooling water, or other fluid medium. In this embodiment, air is considered to be used, and in particular, the odor extracted from the solid waste storage pit is preferably used. The air is first extracted by the air blower to indirectly cool the pyrolysis residue through the cooling jacket 2.21, and at the same time, the air itself is preheated, and then sent to the hot blast furnace 10 as combustion air.

[0049] The high-temperature hot flue gas (controlled at 1000-1100°C) produced by the hot blast furnace 10 is first mixed with part of the medium-temperature flue gas sent by the flue gas fan 12 for temperature adjustment in the hot blast furnace 10, and the temperature of the high-temperature flue gas discharged from the furnace is controlled to be 800-1000°C, and then sent to the heat exchange jacket 2.11 of the pyrolysis section 2.1 of the pyrolysis furnace 2 as a pyrolysis heat source, so that the solid waste undergoes pyrolysis reaction, and then drawn out from the heat exchange jacket 2.11 by the flue gas fan 12, and the outlet temperature is controlled at 350-400°C. In addition to part of the medium-temperature flue gas discharged from the pyrolysis furnace 2 being sent to the hot blast furnace 10 for temperature adjustment, most of it is sent to waste heat utilization and purification treatment before being discharged.

[0050] The synthesis gas obtained by the present invention can be sent to downstream devices for combustion to generate electricity or heat, produce chemical products (natural gas, methanol, synthetic ammonia, etc.), produce hydrogen, and produce liquid fuels.

[0051] The above is only a preferred implementation process of the present invention, and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the protection scope of the present invention.

Claims

1. A moving bed solid waste segmented pyrolysis and gasification method, characterized in that: The following steps are involved: (1) solid waste is sent to a pyrolysis system for pyrolysis to obtain pyrolysis gas and pyrolysis residue; (2) the pyrolysis gas is sent to an organic matter gasification and decomposition system for heating and gasification to remove tar, dioxins and other macromolecular organic matter, and then synthesis gas is obtained after heat recovery, washing, dust removal and acid removal; (3) the pyrolysis residue is cooled and sorted to obtain combustible carbon slag and residual residue.

2. The moving bed solid waste staged pyrolysis and gasification method according to claim 1, characterized in that: In the step (1), the pyrolysis system includes a lock hopper, a pyrolysis furnace, and a hot air furnace for supplying heat to the pyrolysis furnace. The pyrolysis furnace is a moving bed pyrolysis furnace having a vertical cylindrical sleeve structure, and is composed of an upper pyrolysis section and a lower cooling section. Solid waste is fed into the pyrolysis furnace through the lock hopper, and the pyrolysis temperature in the pyrolysis furnace is controlled to be 550 to 650° C. The operating pressure in the furnace is controlled to be -3 kPaG to -0.1 kPaG. The residence time of the solid waste in the pyrolysis section is 10 to 90 minutes, and the pyrolysis residue discharged from the cooling section is cooled to 250 to 350° C.

3. The moving bed solid waste staged pyrolysis and gasification method according to claim 2, characterized in that: In the step (1), the pyrolysis section is provided with a heat exchange jacket, and the cooling section is also provided with a cooling jacket, and both the heat exchange jacket and the cooling jacket are provided with heat exchange fins; the high-temperature flue gas of the hot blast furnace is fed into the heat exchange jacket, and part of the flue gas exiting the heat exchange jacket is fed into the hot blast furnace as temperature-adjusting flue gas for temperature adjustment, and the rest of the flue gas is used to remove waste heat and is utilized by the system, so that the temperature of the high-temperature flue gas exiting the hot blast furnace is controlled to be 800-1000°C.

4. The moving bed solid waste staged pyrolysis and gasification method according to claim 3, characterized in that: In the step (1), air first enters the cooling jacket for preheating and then is sent to the hot air furnace as combustion air.

5. The moving bed solid waste staged pyrolysis and gasification method according to claim 1, characterized in that: In the step (2), the organic matter gasification and decomposition system includes an organic matter decomposition gasifier and a pyrolysis gas retention buffer tank. The pyrolysis gas is first heated to 1050-1100° C. in the organic matter decomposition gasifier, and then sent to the pyrolysis gas retention buffer tank to fully decompose the tar, dioxins and other macromolecular organic matter carried in the pyrolysis gas. The residence time of the pyrolysis gas in the pyrolysis gas retention buffer tank is controlled to be 10-20 seconds, and the temperature of the synthesis gas leaving the pyrolysis gas retention buffer tank is 1000-1050° C.

6. The moving bed solid waste staged pyrolysis and gasification method according to claim 5, characterized in that: In the step (2), the organic matter decomposition gasifier is a cyclone separator structure with 1-3 combustion nozzles on the top. The pyrolysis gas enters from the middle of the organic matter decomposition gasifier and spirally rises. Under the action of the combustion nozzles, the reaction and temperature rise occur, so that the tar, dioxins and other macromolecular organic matter carried in the pyrolysis gas are gasified and decomposed, and the ash carried in the pyrolysis gas is discharged from the bottom outlet of the organic matter decomposition gasifier.

7. The moving bed solid waste staged pyrolysis and gasification method according to claim 5 or 6, characterized in that: In the step (2), the synthesis gas from the pyrolysis gas retention buffer tank is cooled to 180-250°C by a heat recovery system to recover heat, and then washed and deacidified by a synthesis gas washing, dust removal and deacidification system to further reduce the temperature to 30-50°C, and then drawn into the downstream purification process for further treatment by a synthesis gas induced draft fan.

8. The moving bed solid waste staged pyrolysis and gasification method according to claim 1, characterized in that: In the step (3), the pyrolysis residue and the ash separated by the organic matter gasification decomposition system are first cooled to 40-90° C. in a pyrolysis residue cooler, and then sent to a pyrolysis residue sorting system for sorting to obtain combustible carbon slag and residual residue. The combustible carbon slag is sent to a hot blast furnace for combustion as fuel, and the insufficient part is introduced into the synthesis gas obtained in step (2) or supplemented by other external fuels.

9. A moving bed solid waste staged pyrolysis and gasification system for implementing the method of any one of claims 1 to 8, characterized in that: It comprises a pyrolysis system, an organic matter gasification and decomposition system, a heat recovery system, and a synthesis gas washing, dust removal and deacidification system which are connected in sequence. The pyrolysis system comprises a lock hopper, a pyrolysis furnace, and a hot air furnace for supplying heat to the pyrolysis furnace. The pyrolysis gas outlet of the upper section of the pyrolysis furnace is connected to the organic matter gasification and decomposition system, and the bottom outlet of the pyrolysis furnace is connected to the fuel inlet of the hot air furnace via a pyrolysis residue cooler and a pyrolysis residue sorting system.

10. The moving bed solid waste staged pyrolysis and gasification system according to claim 9, characterized in that: The pyrolysis furnace is a moving bed pyrolysis furnace having a vertical cylindrical sleeve structure, and is composed of an upper pyrolysis section and a lower cooling section. The pyrolysis section is provided with a heat exchange jacket, and the cooling section is provided with a cooling jacket. Heat exchange fins are provided in the heat exchange jacket and the cooling jacket.

11. The moving bed solid waste staged pyrolysis and gasification system according to claim 9, characterized in that: The flue gas outlet of the hot blast stove is connected to the flue gas inlet of the heat exchange jacket, the flue gas outlet of the heat exchange jacket is connected to the temperature-adjusting flue gas inlet of the hot blast stove, and the outlet of the synthesis gas washing, dust removal and deacidification system is also connected to the fuel inlet of the hot blast stove.

12. The moving bed solid waste staged pyrolysis and gasification system according to claim 10 or 11, characterized in that: The cooling jacket has an air inlet and an air outlet, wherein the air inlet is connected to the air blower outlet, and the air outlet is connected to the air inlet of the hot air furnace.

13. The moving bed solid waste staged pyrolysis and gasification system according to any one of claims 9 to 11, characterized in that: The organic matter gasification and decomposition system comprises an organic matter decomposition gasifier and a pyrolysis gas retention buffer tank. The pyrolysis gas outlet of the upper section of the pyrolysis furnace is connected to a heat recovery system via the organic matter decomposition gasifier and the pyrolysis gas retention buffer tank.

14. The moving bed solid waste staged pyrolysis and gasification system according to claim 13, characterized in that: The organic matter decomposition gasifier is a cyclone separator structure with 1-3 combustion nozzles on the top. The middle inlet of the organic matter decomposition gasifier is connected to the pyrolysis furnace, the top outlet is connected to the pyrolysis gas retention buffer tank, and the bottom outlet is connected to the pyrolysis residue cooler.

15. The moving bed solid waste staged pyrolysis and gasification system according to claim 13, characterized in that: The connecting pipeline between the pyrolysis furnace and the organic matter decomposition gasifier has an upward inclination angle, and the angle is controlled at 30 to 60 degrees.

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