Production process of clean producer gas

Abstract

The invention provides a production process of clean producer gas, which comprises the following steps: adding carbon residue produced by a rotary gas producer into the furnace from a feeding end, raising the temperature in the heating process of the carbon residue, and carrying out carbon gasification reaction on the carbon residue and H2O and CO2 in furnace gas in a carbon gasification area I; in the coal full pyrolysis zone, water gas reaction is carried out with water vapor released by heating of low-rank coal sprayed from a discharge end, volatile components released by pyrolysis of the low-rank coal are fully pyrolyzed at high temperature, and producer gas with high calorific value is produced; when the carbon residue advances to the second carbon gasification area, part of high-temperature carbon residue is in contact with air or oxygen-enriched air for combustion and supplies heat to the interior of the furnace, the residual high-temperature carbon residue enters the vertical gasification furnace after being discharged from the discharging end, and high-calorific-value coal gas is produced from the carbon residue in the boiling gasification process under the action of water vapor; the residual carbon residue is cooled by a rotary cooling furnace and is subjected to dry separation by a dry magnetic separator, so that the carbon residue and a metallized material can be obtained; and finally, the metallized material is ground and separated by a dry grinding and separating machine to obtain iron powder and coal ash.

Description

Technical Field

[0001] The invention belongs to the technical field of energy engineering, and in particular relates to a clean producer gas production process. Background Art

[0002] The gasifier converts coal into combustible gas - generator gas (mainly CO, H 2 , CH 4 The working principle of this equipment is as follows: after screening coal (generally low-rank coal) that is suitable for gasification process indicators, coal with a particle size of less than 10 mm is added to the gasifier by the stoker, and steam and air mixed gas is blown into the bottom of the furnace as a gasifier. The coal is physically heated and chemically reacted in the furnace to generate combustible gas - gasifier gas. At present, the commonly used gasifier in industry is the vertical gasifier.

[0003] The material layers of the vertical gasifier are drying layer, preheating layer, dry distillation layer, carbon gasification layer, and oxidation combustion layer from top to bottom. Coal is added to the coal silo from the coal feeding port, and then added from the top of the gasifier through the spiral air lock feeder. The steam and air mixture is passed from the grate at the bottom of the material layer from bottom to top to the bottom of the material layer. The coal passes through the empty layer, drying layer, preheating layer, dry distillation layer, carbon gasification layer, and oxidation combustion zone in the furnace in turn, and is dried, preheated, dry distilled, carbonized, and oxidized. The produced gas is discharged from the crude gas outlet at the top of the vertical gasifier. The coal ash produced after coal gasification falls through the grate to the dust storage area and is finally discharged from the ash outlet.

[0004] Figure 1 This is a diagram of the existing vertical gas generator equipment.

[0005] Vertical coal gasifiers can be single-stage or double-stage. When a double-stage furnace is used, the coal gas produced in the upper section of the furnace is coal pyrolysis gas, which contains tar, benzene, naphthalene, alkane, olefin, hydrocarbons and other high molecular weight gases and H 2 , H 2 O, CO, CO 2 , H 2 S and other small molecular weight gases, coal gas has a high calorific value, and generally needs to be purified by cyclone oil remover and electric precipitator to filter tar before use; the coal gas produced in the lower section of the furnace is carbon gasification gas, and the coal gas contains H 2 ,CO,N 2 , CO 2 Gases such as coal gas have a low calorific value and generally need to be dedusted by a cyclone dust collector. The resulting coal gas is then mixed with the upper coal gas for use by users.

[0006] The coal added to the vertical gasifier is pyrolyzed, carbonized, and oxidized to produce gas without carbon circulation. The calorific value of the gas obtained by the gasifier is generally 6100-6500KJ / Nm 3 . As the material layer of the vertical gasifier is relatively thin, in order to prevent the segregation of materials and airflow in the furnace, the gas output of a single furnace is generally not large. As the material layer of the vertical gasifier is generally thicker, the sensible heat of the gas in the gasifier can be fully recovered, and the gas outlet temperature is generally below 200℃.

[0007] Low-rank coal is a young type of coal with a low degree of carbonization, a volatile matter yield of over 40%, a high moisture content, and poor calorific value stability. When low-rank coal is used as a gasification raw material in a vertical gasifier, the gas production rate is low, while the tar yield is very high. Summary of the invention

[0008] The present invention provides a clean gas production process for a vertical gasifier to solve the problems of low production capacity of a single device, need for subsequent treatment of the gas, low calorific value of the gas, and high tar yield in the existing vertical gasifier.

[0009] The main equipment involved in the present invention includes: rotary gasifier, vertical gasifier, gas mixer, rotary cooling furnace, dry magnetic separator, dry grinding and dry separator. The main materials involved include: iron ore concentrate, granular coal, fuel, oxygen-enriched air, water vapor, water, high-temperature materials, metallized materials, iron powder, residual carbon, coal ash, generator gas, high calorific value gas, and medium calorific value gas.

[0010] The rotary coal gasifier of the present invention is similar to the rotary kiln commonly used in the metallurgical industry, and consists of a rotary furnace body, a lifting plate, a second carbon gasification zone, a coal full pyrolysis zone, a first carbon gasification zone, a preheating zone, a drying zone, a furnace start-up burner, a kiln back draft fan, a blower, refractory materials, a coarse-grained coal spray gun, a fine-grained coal spray gun, a steam spray gun, an oxygen-enriched spray gun, a Roots blower, a blower, a coarse-grained coal feeding port, and a fine-grained coal feeding port. The rotary kiln body is cylindrical, with refractory materials and lifting plates inside. The height of the kiln feeding end is higher than that of the discharging end in the vertical direction, and the rotary kiln body rotates under the action of the transmission system; the materials added into the furnace from the feeding end continuously flow from the feeding end to the discharging end under the action of the rotation of the furnace body; a smoke exhaust pipe and a kiln tail feeding port are provided on the kiln tail hood at the feeding end, and a coarse-grained coal spray gun, a fine-grained coal spray gun, a steam spray gun, an oxygen-enriched spray gun, a furnace start-up burner and a high-temperature mixed material discharge port are provided on the kiln head hood at the discharging end; a kiln back draft fan is provided outside the rotary kiln body; the furnace is divided into a drying zone, a preheating zone, a carbon gasification zone 1, a coal full pyrolysis zone and a carbon gasification zone 2 from the feeding end to the discharging end.

[0011] The process of the present invention is as follows: the residual carbon and iron ore produced by the rotary gasifier are added into the furnace from the feed end, the temperature of the mixed material increases during the heating process, and the residual carbon in the mixed material and H in the furnace gas are mixed in the first carbon gasification zone. 2 O and CO 2 Carry out carbon gasification reaction, in the coal full pyrolysis zone, the residual carbon in the mixed material reacts with the water vapor released by the low-rank coal sprayed from the discharge end, and the low-rank coal releases volatiles by pyrolysis, which are fully pyrolyzed at high temperature to produce high calorific value producer gas; when the mixed material moves to the second carbon gasification zone, part of the residual carbon in the mixed material contacts with air or oxygen-enriched air to burn and supply heat to the furnace, and the remaining mixed material is discharged from the discharge end and enters the vertical gasification furnace, and the residual carbon in the mixed material produces high calorific value gas in the boiling gasification process under the action of water vapor, and the remaining mixed material is cooled by a rotary cooling furnace and dry-selected by a dry magnetic separator to obtain residual carbon and metallized material; the metallized material is finally ground by a dry grinding and dry selecting machine to obtain iron powder and coal ash.

[0012] To realize the above process, the production steps adopted are: (1) The low-rank coal used in the present invention has a particle size of 0-10 mm. The low-rank coal is classified into two particle size ranges of 0-5 mm fine coal and 5-10 mm coarse coal using a 5 mm vibrating screen; (2) The carbon residue selected by the dry magnetic separator is returned to the batching system of the rotary gasifier, and the carbon residue and the iron ore concentrate are batched and mixed in a ratio of 100:5-6 to obtain a mixed material, which is added from the feed end of the rotary gasifier; (3) After the mixed material is added to the rotary gasifier, the mixed material tumbles continuously under the action of the furnace body rotation and flows from the inlet end to the outlet end. During the tumbling and moving process, the mixed material exchanges heat with the high-temperature gas flowing in the furnace in the opposite direction, causing the temperature of the mixed material to gradually increase; (4) When the carbon residue is in the drying zone of the rotary gasifier and the temperature rises to above 100°C, the carbon residue is dried; when the carbon residue moves to the preheating zone and the temperature rises to above 200°C, the carbon residue is preheated; (5) When the mixed material moves to the carbon gasification zone 1 of the rotary gasifier and the temperature rises to above 800°C, the residual carbon in the mixed material reacts with the water vapor and CO in the furnace gas. 2 Carbon gasification reaction produces CO and H 2 It enters the furnace gas, increasing the calorific value of the gas in the furnace; at the same time, the iron concentrate in the mixed material is reduced step by step under the action of the reducing atmosphere; (6) A coarse coal spray gun and a fine coal spray gun are arranged at the discharge end of the rotary gasifier. When the mixed material reaches the coal full pyrolysis zone and the temperature rises to about 1000°C, the coarse coal spray gun is used to spray the coarse coal into the front half of the coal full pyrolysis zone with compressed air as the spray medium. The coarse coal contacts the high-temperature furnace gas during the parabolic motion along the center line of the kiln body in the furnace, and its temperature rises rapidly. Water and volatiles are discharged from the coarse coal into the furnace gas. The coarse coal falls to the surface of the residual carbon at the bottom of the furnace body under the action of gravity. The residual carbon rolls the coarse coal into the material layer during the tumbling flow in the furnace. The temperature of the coarse coal rises rapidly under the combined action of the high-temperature furnace gas and the high-temperature residual carbon. When the coal is at 100-200°C, a large amount of water vapor is discharged from the coal. When the water vapor contacts the high-temperature residual carbon, a violent carbon gasification reaction may occur to generate H 2 When the temperature of coal is 350-400℃, coal begins to pyrolyze into carbon-rich stagnant carbon and hydrogen-rich volatiles. The pyrolysis of coal under low temperature conditions is not sufficient, and the hydrogen-rich volatiles produced contain tar, benzene, naphthalene, alkane, olefins, hydrocarbons and other high molecular weight gases and H 2 , H 2 O, CO, CO 2 , H 2 In the roasting material layer space in the furnace, the temperature reaches above 950°C, and the volatiles such as tar, benzene, naphthalene, alkane, olefin, hydrocarbon and other large molecular weight gases will undergo secondary and multiple pyrolysis, and the final gas product will be H 2 Mainly, a large amount of solid active granular carbon is produced at the same time; except for a small part of the gas produced inside the material layer that is reduced to iron oxide to generate metallic iron, the rest of the gas overflows the material layer and enters the furnace space to be used as coal gas.

[0013] (7) When the mixed material in the rotary gasifier reaches the second half of the coal full pyrolysis zone, the fine coal is sprayed into the second half of the coal full pyrolysis zone using a fine coal spray gun with compressed air as the spray medium. The fine coal contacts the high-temperature furnace gas during the parabolic motion along the center line of the kiln body in the furnace, and its temperature rises rapidly. What happens to the fine coal in the furnace is similar to that of the coarse coal, and will not be explained here.

[0014] (8) When the mixed material in the rotary gasifier moves to the second carbon gasification zone, oxygen-enriched air and water vapor are blown into the kiln from the discharge end of the rotary gasifier. At the same time, the kiln back draft fan is used to blow normal temperature air into the kiln along the kiln length. The residual carbon in the high-temperature mixed material is burned under the action of oxygen-enriched air and air to produce CO and CO 2 The heat generated by combustion is used to heat the rotary gasifier, and the steam blown in and the CO produced by combustion are 2 The hot carbon residue undergoes carbon gasification reaction to produce CO and H 2 , CO and H2 After entering the furnace space, it is discharged as coal gas; at the same time, under the high temperature of fuel combustion, the iron ore reduction material and the coal ash produced by the residual carbon are combined into metallized materials.

[0015] (9) When the mixed material in the rotary gasifier flows to the discharge end, the high-temperature mixed material of 900-1000℃ is discharged from the furnace.

[0016] (10) The coal gas produced by the carbon gasification reaction in the rotary gasifier and the coal gas produced by the pyrolysis of low-rank coal enter the furnace space and are finally discharged from the feeding end of the rotary kiln. The coal gas is used as the generator gas.

[0017] (11) The high-temperature mixed material discharged from the rotary gasifier enters the vertical gasifier. Under the action of high-temperature steam, the residual carbon reacts with water vapor during boiling and produces H 2 and CO, and the gasified low-temperature mixed material is discharged from the vertical gasifier.

[0018] (12) The generator gas discharged from the rotary gasifier and the high calorific value gas discharged from the vertical gasifier are mixed and pressurized in a gas mixer to obtain medium calorific value gas, which can be directly supplied to users for use.

[0019] (13) The rotary cooling furnace is equipped with water inlet and outlet devices, and cooling water is used to indirectly cool the low-temperature materials. The low-temperature materials below 600°C discharged from the vertical gasification furnace enter the rotary cooling furnace, and the temperature of the low-temperature materials is reduced to below 200°C under the cooling effect of the circulating cooling water; (14) The low-temperature material after cooling is added to a dry magnetic separator, which can separate the low-temperature material into metallized material and residual carbon. The residual carbon is returned to the batching system of the rotary gasifier for recycling, and the metallized material is ground by a dry grinding and dry separator to separate it into fly ash and iron powder. The fly ash is used as a building material product, and the iron powder is sold as a product.

[0020] In order to make the carbon residue fully contact with furnace gas to carry out carbon gasification reaction during the flow of carbon residue in the rotary gasifier, the present invention arranges a plurality of lifting plates on the rotary furnace shell in the coal full pyrolysis zone and the carbon gasification zone inside the furnace body. Each lifting plate is arranged into a multi-section arc surface structure along the cross section of the rotary gasifier, which can drive the carbon residue at the bottom of the furnace body to the middle and upper part of the furnace body during the rotation of the rotary furnace body, and make the carbon residue fall evenly from the upper part during the rotation of the furnace body.

[0021] In order to fully exchange heat between the furnace gas in the rotary gasifier and the mixed material flowing in the opposite direction from the discharge end to the feed end, each lifting plate is arranged in a spiral shape on the furnace shell of the rotary furnace along the furnace length direction.

[0022] The present invention arranges a furnace start-up burner at the discharge end of the rotary gasifier. The furnace start-up burner is only used when heat needs to be supplied to the furnace during the processes of starting the furnace, stuffing the furnace and stopping the furnace. During normal production, only air is introduced into the furnace start-up burner, and the air is used together with oxygen-enriched air as the combustion-supporting air of the rotary gasifier. The fuel of the furnace start-up burner can be coal gas or coal powder, and air is blown in by a blower to cause the fuel to burn and supply heat to the furnace.

[0023] In order to improve the gasification effect and thermal energy utilization efficiency of low-rank coal, the filling rate of residual carbon in the rotary gasifier is relatively high, generally 20-30%, and the aspect ratio of the furnace body is 20-25.

[0024] The present invention adds iron concentrate to the feeding end of the rotary gasifier, and the addition ratio of the iron concentrate is 5-8% of the amount of granular coal injected. After being heated and reduced in the furnace, the iron concentrate is combined with the coal ash generated by the reduction of the residual carbon in the furnace to form a metallized material, and the metallized material is discharged from the discharging end together with the residual carbon.

[0025] According to the different effects of low-rank coal particle size on the pyrolysis time and gasification time of coal, the present invention classifies the particle size of low-rank coal into two particle size ranges of coarse coal and fine coal in order to make better use of low-rank coal of different particle sizes in the furnace. The coarse coal is sprayed to a position farther from the discharge end, and the fine coal is sprayed to a position closer to the discharge end.

[0026] In order to prolong the carbon gasification reaction time of the residual carbon in the second carbon gasification zone in the rotary gasifier and improve the carbon gasification quality, 3-5 kiln back fans are arranged on the kiln back of the second carbon gasification zone along the furnace length direction. Air is blown into different positions in the furnace through the kiln back fans at different positions of the furnace body, so that the residual carbon can be burned and gasified at different positions in the furnace.

[0027] Figure 2 This is the process flow chart for the production of clean producer gas; Figure 3 This is the equipment diagram of the rotary gasifier; Figure 4 This is the structural diagram of the lifting plate in the rotary gasifier.

[0028] The beneficial effects of the present invention are: (1) The present invention adds the residual carbon that does not contain tar, benzene, naphthalene, alkanes, alkenes, hydrocarbons and other large molecular weights produced by the rotary gasifier from the feed end, and sprays the low-rank coal that contains tar, benzene, naphthalene, alkanes, alkenes, hydrocarbons and other large molecular weights from the discharge end into the coal full pyrolysis zone with a higher temperature, thereby producing clean coal gas that does not contain tar, benzene, naphthalene, alkanes, alkenes, hydrocarbons and other large molecular weights.

[0029] (2) The coal filling rate in the rotary gasifier of the present invention is relatively high, and by arranging a lifting plate on the furnace body of the rotary furnace, the furnace gas and the residual carbon can be fully contacted, and the volatile matter volatilized by the low-rank coal is fully pyrolyzed in the furnace, thereby improving the production capacity of a single device. At the same time, oxygen-enriched air is used as a combustion aid for the residual carbon to produce high calorific value gas.

[0030] (3) The vertical gasifier of the present invention makes full use of the waste heat of high-temperature residual carbon and adopts boiling gasification technology. The carbon gasification reaction speed is fast and the adaptability to pulverized coal gasification is high.

[0031] (4) The present invention recycles the residual carbon. In view of the fact that the residual carbon after gasification of low-rank coal contains coal ash, a small amount of iron ore concentrate is added to the feed end of the rotary gasifier to separate the coal ash from the residual carbon. The iron ore concentrate is reduced in the furnace and then combined with the coal ash to form a metallized material. The metallized material is separated from the residual carbon and the coal ash by magnetic separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the equipment diagram of the existing vertical gasifier; Figure 2 This is a process flow chart of the clean producer gas production process of the present invention; Figure 3 This is a diagram of the rotary gas generator equipment of the present invention; Figure 4 This is a structural diagram of the material lifting plate in the rotary gasifier of the present invention. DETAILED DESCRIPTION

[0033] The present invention discloses a clean producer gas production process, the equipment involved includes: a rotary gasifier, a vertical gasifier, a gas mixer, a rotary cooling furnace, a dry magnetic separator, a dry grinding and dry separator, the main materials involved include: iron ore concentrate, granular coal, fuel, oxygen-enriched air, water vapor, water, high-temperature materials, metallized materials, iron powder, residual carbon, coal ash, producer gas, high calorific value gas, medium calorific value gas, and the specific implementation method is as follows: (1) Low-rank coal with a particle size of 0-10 mm is classified into two particle size ranges: 0-5 mm fine coal and 5-10 mm coarse coal using a 5 mm vibrating screen.

[0034] (2) The residual carbon selected by the dry magnetic separator is returned to the batching system of the rotary gasifier. The residual carbon and the iron ore concentrate are batched and mixed in a ratio of 100:5-6 to obtain a mixed material, which is added from the feed end of the rotary gasifier.

[0035] (3) The mixed material tumbles continuously under the action of the rotation of the furnace body and flows from the inlet end to the outlet end. The mixed material exchanges heat with the countercurrent high-temperature gas, causing the temperature of the mixed material to gradually increase.

[0036] (4) When the carbon residue is in the drying zone of the rotary gasifier and the temperature rises to above 100°C, the carbon residue is dried. When the carbon residue moves to the preheating zone and the temperature rises to above 200°C, the carbon residue is preheated.

[0037] (5) When the mixed material moves to the carbon gasification zone 1 of the rotary gasifier and the temperature rises to above 800°C, the residual carbon in the mixed material reacts with the water vapor and CO in the furnace gas. 2 Carbon gasification reaction produces CO and H 2 It enters the furnace gas and the iron concentrate in the mixed material is reduced step by step.

[0038] (6) When the mixed material reaches the coal full pyrolysis zone and the temperature rises to about 1000°C, the coarse coal is sprayed into the front half of the coal full pyrolysis zone using a coarse coal spray gun. The coarse coal is rolled into the material layer during the tumbling flow of the residual carbon in the furnace. When the coal is at 100-200°C, the water vapor discharged from the coal reacts with the high-temperature residual carbon to form H 2 When the coal is at 350-400℃, it is pyrolyzed into carbon-rich stagnant carbon and hydrogen-rich volatiles. Under the condition of 1000℃ in the furnace, the gas product of the final pyrolysis of the volatiles is H 2 Mainly, a large amount of solid active granular carbon is produced at the same time; except for a small part of the gas inside the material layer that is used for iron oxide reduction, the rest of the gas overflows the material layer and enters the furnace space to be used as coal gas.

[0039] (7) When the mixed material in the rotary gasifier reaches the second half of the coal full pyrolysis zone, a fine-grained coal spray gun is used to spray fine-grained coal into the second half of the coal full pyrolysis zone. What happens to the fine-grained coal in the furnace is similar to that of the coarse-grained coal and will not be explained here.

[0040] (8) When the mixed material in the rotary gasifier moves to the second carbon gasification zone, oxygen-enriched air and water vapor are blown into the kiln from the discharge end. At the same time, the kiln back draft fan is used to blow normal temperature air into the kiln along the kiln length. The residual carbon in the high-temperature mixed material is burned under the action of oxygen-enriched air and air to produce CO and CO 2The heat generated by combustion is used to heat the rotary gasifier, and the steam blown in and the CO produced by combustion are 2 The hot carbon residue undergoes carbon gasification reaction to produce CO and H 2 , CO and H 2 After entering the furnace space, it is discharged as coal gas; at the same time, the iron ore reduction material and the coal ash produced by the residual carbon are combined into metallized materials.

[0041] (9) When the mixed material in the rotary gasifier flows to the discharge end, the high-temperature mixed material of 900-1000℃ is discharged from the furnace.

[0042] (10) The coal gas produced by the carbon gasification reaction in the rotary gasifier and the coal gas produced by the pyrolysis of low-rank coal enter the furnace space and are finally discharged from the feeding end of the rotary kiln.

[0043] (11) The high-temperature mixed material discharged from the rotary gasifier enters the vertical gasifier. Under the action of high-temperature steam, the residual carbon reacts with water vapor during boiling and produces H 2 and CO, and the gasified low-temperature mixed material is discharged from the vertical gasifier.

[0044] (12) The generator gas discharged from the rotary gasifier and the high calorific value gas discharged from the vertical gasifier are mixed and pressurized in a gas mixer to obtain medium calorific value gas.

[0045] (13) Cooling water is used in the rotary cooling furnace to indirectly cool the low-temperature material, which can reduce the temperature of the low-temperature material around 600°C to below 200°C.

[0046] (14) The low-temperature material after cooling is added to the dry magnetic separator, which can separate the low-temperature material into metallized material and residual carbon. The residual carbon is returned to the batching system of the rotary gasifier for recycling, and the metallized material is ground and separated into fly ash and iron powder by the dry grinding and dry separator.

Claims

1. A clean gas generator process, the equipment involved includes: a rotary gas generator, a vertical gasification furnace, a gas mixer, a rotary cooling furnace, a dry magnetic separator, and a dry grinding and dry separator; The kiln tail cover at the feeding end of the rotary gasifier is provided with a smoke exhaust pipe and a kiln tail feeding port, and the kiln head cover at the discharging end is provided with a coarse coal spray gun, a fine coal spray gun, a steam spray gun, an oxygen-enriched spray gun, a furnace start-up burner and a high-temperature mixed material discharge port; a kiln back draft fan is provided outside the furnace body of the rotary gasifier, and the furnace is divided into a drying zone, a preheating zone, a carbon gasification zone 1, a coal full pyrolysis zone and a carbon gasification zone 2 from the feeding end to the discharging end, and is characterized by: The residual carbon and iron concentrate produced by the rotary gasifier are added into the furnace from the feeding end. The temperature of the mixed material increases during the heating process. In the carbon gasification zone, the residual carbon in the mixed material reacts with H2O and CO2 in the furnace gas for carbon gasification. In the coal full pyrolysis zone, the residual carbon in the mixed material reacts with the water vapor released by the low-rank coal injected from the discharge end for water gas reaction. The low-rank coal releases volatiles by pyrolysis and fully pyrolyzes at high temperature to produce high calorific value gas. When the mixed material moves When it reaches the second carbon gasification zone, part of the residual carbon in the mixture comes into contact with air or oxygen-enriched air to burn and provide heat to the furnace. The remaining mixture is discharged from the discharge end and enters the vertical gasification furnace. The residual carbon in the mixture produces high calorific value coal gas in the boiling gasification process under the action of water vapor. The remaining mixture is cooled in a rotary cooling furnace and dry-selected by a dry magnetic separator to obtain residual carbon and metallized materials. The metallized materials are finally ground by a dry grinder and dry separator to obtain iron powder and coal ash.

2. The clean producer gas production process according to claim 1, characterized in that: The furnace body of the rotary gasifier is cylindrical, with refractory materials and lifting plates inside. In the vertical direction, the height of the kiln body feed end is higher than the height of the discharge end. The rotary gasifier rotates under the action of the transmission system; the material added into the furnace from the feed end continuously flows from the feed end to the discharge end under the action of the rotation of the furnace body.

3. The clean producer gas production process according to claim 1, characterized in that: To produce clean producer gas, the following process is used: (1) Using a 5 mm vibrating screen, the low-rank coal with a particle size of 0-10 mm is classified into two particle size ranges: 0-5 mm fine coal and 5-10 mm coarse coal; (2) The carbon residue selected by the dry magnetic separator is returned to the batching system of the rotary gasifier, and the carbon residue and the iron ore concentrate are batched and mixed in a ratio of 100:5-6 to obtain a mixed material, which is added from the feed end of the rotary gasifier; (3) After the mixed material is added to the rotary gasifier, the mixed material tumbles continuously under the action of the furnace body rotation and flows from the inlet end to the outlet end. During the tumbling and moving process, the mixed material exchanges heat with the high-temperature gas flowing in the furnace in the opposite direction, causing the temperature of the mixed material to gradually increase; (4) When the carbon residue is in the drying zone of the rotary gasifier and the temperature rises to above 100°C, the carbon residue is dried; when the carbon residue moves to the preheating zone and the temperature rises to above 200°C, the carbon residue is preheated; (5) When the mixed material moves to the carbon gasification zone 1 of the rotary gasifier and the temperature rises to above 800°C, the residual carbon in the mixed material reacts with the water vapor and CO2 in the furnace gas to undergo carbon gasification reaction. The produced CO and H2 enter the furnace gas, increasing the calorific value of the gas in the furnace. At the same time, the iron ore concentrate in the mixed material is reduced step by step under the action of the reducing atmosphere. (6) In the rotary gasifier, when the mixed material reaches the coal full pyrolysis zone and the temperature rises to 1000℃, the coarse coal spray gun and the fine coal spray gun are used to spray the coarse coal and the fine coal into the front and rear halves of the coal full pyrolysis zone with compressed air as the spray medium. The coal particles come into contact with the high-temperature furnace gas during the parabolic motion along the center line of the kiln body in the furnace, and the temperature rises rapidly. Water and volatiles are discharged from the coal particles into the furnace gas. The coal particles fall to the surface of the residual carbon at the bottom of the furnace body under the action of gravity. The residual carbon rolls the coal particles into the material layer during the tumbling flow in the furnace. Under the combined action of the high-temperature furnace gas and the high-temperature residual carbon, the temperature of the coal particles rises rapidly. At 100-200℃, a large amount of water vapor is discharged from the coal. When the water vapor contacts the high-temperature residual carbon, a violent carbon gasification reaction may occur to generate H2 and CO. When the coal is at 350-400℃, the coal begins to pyrolyze into carbon-rich stagnant carbon and hydrogen-rich volatiles. In the roasting material layer space in the furnace, the temperature reaches above 950℃, and the tar, benzene, naphthalene, alkane, alkene, hydrocarbon and other large molecular weight gases in the volatiles will undergo secondary and multiple pyrolysis, and a large amount of solid active granular carbon will be produced at the same time. A small part of the gas produced inside the material layer is reduced to iron oxide to generate metallic iron, and the rest of the gas overflows the material layer and enters the furnace space to be used as coal gas. (7) When the mixed material in the rotary gasifier moves to the second carbon gasification zone, oxygen-enriched air and water vapor are blown into the kiln from the discharge end of the rotary gasifier. At the same time, the kiln back draft fan is used to blow normal temperature air into the kiln along the length of the kiln. The residual carbon in the high-temperature mixed material is burned under the action of the oxygen-enriched air and air to produce CO and CO2. The heat generated by the combustion is used to supply heat to the rotary gasifier. The blown-in water vapor, the CO2 produced by the combustion and the hot residual carbon undergo carbon gasification reaction to finally produce CO and H2. After the CO and H2 enter the furnace space, they are discharged as coal gas. At the same time, under the action of the high temperature of the fuel combustion, the iron ore reduction material and the coal ash produced by the residual carbon are combined to form metallized materials. (8) When the mixed material in the rotary gasifier flows to the discharge end, the high-temperature mixed material of 900-1000℃ is discharged from the furnace; (9) The coal gas produced by the carbon gasification reaction in the rotary gasifier and the coal gas produced by the pyrolysis of low-rank coal enter the furnace space and are finally discharged from the feeding end of the rotary kiln. The coal gas is used as the generator gas; (10) The high-temperature mixed material discharged from the discharge end of the rotary gasifier enters the vertical gasifier. Under the action of high-temperature steam, the residual carbon reacts with water vapor during boiling movement to produce H2 and CO. The gasified low-temperature mixed material is discharged from the vertical gasifier. (11) The generator gas discharged from the rotary gasifier and the high calorific value gas discharged from the vertical gasifier are mixed and pressurized in a gas mixer to obtain medium calorific value gas; (12) Using cooling water to indirectly cool low-temperature materials in a rotary cooling furnace; The low-temperature materials below 600℃ discharged from the vertical gasification furnace enter the rotary cooling furnace, and the temperature of the low-temperature materials is reduced to below 200℃ under the cooling effect of circulating cooling water; (13) The cooled low-temperature material is added to a dry magnetic separator to separate the low-temperature material into metallized material and residual carbon. The residual carbon is returned to the batching system of the rotary gasifier for recycling, while the metallized material is ground and separated into fly ash and iron powder by a dry grinding and dry separator.

4. The clean producer gas production process according to claim 1 or 3, characterized in that: A plurality of lifting plates are arranged on the rotary furnace shell in the coal full pyrolysis zone and the carbon gasification zone in the rotary gasifier, and each lifting plate is arranged into a multi-section arc surface structure along the cross section of the rotary gasifier; During the rotation of the furnace body, the residual carbon at the bottom of the furnace body is driven to the upper middle part of the furnace body, and the residual carbon is made to fall evenly from the upper part during the rotation of the furnace body.

5. The clean producer gas production process according to claim 4, characterized in that: The lifting plate is arranged in a spiral shape on the shell of the rotary furnace along the length direction of the furnace.

6. The clean producer gas production process according to claim 1 or 3, characterized in that: The filling rate of residual carbon in the rotary gasifier is 20-30%, and the aspect ratio of the furnace body is 20-25.

7. The clean producer gas production process according to claim 1 or 3, characterized in that: At the feeding end of the rotary gasifier, the addition ratio of iron ore concentrate is 5-8% of the amount of granular coal injected. After being heated and reduced in the furnace, the iron ore concentrate is combined with the coal ash produced by the reduction of the residual carbon in the furnace to form a metallized material.

8. The clean producer gas production process according to claim 1 or 3, characterized in that: 3-5 kiln back fans are installed along the length of the rotary gasifier on the kiln back of the carbon gasification zone 2. Air is blown into different positions of the furnace through the kiln back fans at different positions of the furnace body, so that the residual carbon can be burned and gasified at different positions in the furnace.

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