CN103045307B - A pyrolysis gasification method and pyrolysis gasification device for preparing tar-free hydrogen-rich gas - Google Patents

Abstract

The invention relates to the technical field of solid fuel energy chemical industry, in particular, the invention relates to a pyrolysis gasification method and a pyrolysis gasification device for preparing tar-free hydrogen-rich gas. The pyrolysis and gasification method for preparing tar-free hydrogen-rich gas of the present invention includes the following steps: 1) Sending carbon-containing solid raw materials into an upstream pyrolysis reactor through a feeding device for aerobic pyrolysis to produce pyrolysis gas phase products and solid products; 2) Pass the pyrolysis gas phase products and solid products produced in step 1) into the downstream tar cracking reactor, and remove tar through high-temperature pyrolysis, partial oxidation and catalytic cracking reactions of pyrolysis semi-coke; Coke is partially gasified to obtain pyrolysis gas and pyrolysis semi-coke. The invention avoids the problems of burning volatile matter while fuel combustion provides heat in the traditional process, resulting in low content of H ₂ and CH ₄ in the pyrolysis gas, and large processing capacity of subsequent gas composition reforming reaction.

Description

A pyrolysis gasification method and pyrolysis gasification device for preparing tar-free hydrogen-rich gas

technical field

The invention relates to the technical field of solid fuel energy chemical industry, in particular, the invention relates to a pyrolysis gasification method and a pyrolysis gasification device for preparing tar-free hydrogen-rich gas.

Background technique

The gasification of carbon-containing solid fuels (coal, biomass and other carbon-containing solid wastes, etc.) is an important way in the process of its utilization. At present, the gasification process in industrial operation generally adopts the autothermal method, that is, the heat required in the gasification reaction process is provided by burning part of the gasification raw materials. Due to the high reaction temperature in the whole gasification process, it is necessary to burn more than 40% of carbon-containing raw materials to maintain the temperature required for the reaction (above 1000°C). In this process, not only part of the gasification raw materials are burned, but also useful gas components such as H ₂ and CH ₄ are also burned at the same time, so that the ratio of H ₂ /CO in the obtained gas is greatly reduced. As an efficient and clean gas resource, H ₂ has a large demand in subsequent processes such as methane synthesis and ammonia synthesis. Take synthetic methane as an example: In actual production, H ₂ /CO=3.0 is required in the feed gas, but the Lurgi furnace process with the highest H ₂ /CO ratio in the outlet gas composition of the current gasification process is only about 1.6. Therefore, in order to meet the needs of subsequent industrial production, the resulting atmosphere must be reformed to adjust the composition of the gas. The whole process is cumbersome and complicated to operate, and is accompanied by a large amount of energy consumption. Although the H ₂ content in the gas produced by the coal-to-semi-coke process is greatly increased, a large amount of tar is associated with the dry distillation gas obtained at the same time, which makes the gas purification process complicated and the equipment operation stability is poor. In order to solve the above problems, some studies have been carried out, such as the patent: CN101045525 proposes that in a spouted bed or fluidized bed reactor under high pressure conditions, water vapor is used as the gasification gas, and carbon dioxide is fully absorbed by adding a carbon dioxide absorbent to achieve The purpose of increasing the hydrogen production rate. However, this process is carried out under high pressure conditions, and the carbon dioxide absorbent KOH or Ca(OH) ₂ agglomerates seriously, which affects the normal operation of the process. At the same time, the production of tar and its treatment in the whole process have not been mentioned.

From the above analysis, it can be seen that there are urgent problems to be solved in the gasification process: first, try to increase the content of high-quality gases such as H ₂ and CH ₄ in the gasification gas, so as to increase the ratio of H ₂ /CO and reduce the subsequent reforming reaction. The second is to remove the tar in the obtained gasification gas to the greatest extent.

Contents of the invention

The object of the present invention is to provide a pyrolysis gasification method for preparing tar-free hydrogen-rich gas in order to solve the above problems.

Another object of the present invention is to provide a pyrolysis gasification device based on the above pyrolysis gasification method for preparing tar-free hydrogen-rich gas.

The pyrolysis gasification method for preparing tar-free hydrogen-rich gas of the present invention comprises the following steps:

1) Send carbon-containing solid raw materials into the upstream pyrolysis reactor through the feeding device for aerobic pyrolysis to produce pyrolysis gas phase products and solid products;

2) The pyrolysis gas phase products and solid products produced in step 1) are passed into the downstream tar cracking reactor, and the tar is removed through high-temperature pyrolysis, partial oxidation and pyrolysis semi-coke catalytic cracking reaction, and at the same time, part of the gas is generated by pyrolysis semi-coke chemical reaction to obtain pyrolysis gas and pyrolysis semi-coke.

According to the pyrolysis gasification method of the present invention, the carbon-containing solid raw material is coal, biomass or other carbon-containing solid wastes.

According to the pyrolysis gasification method of the present invention, the reaction temperature in the upstream pyrolysis reactor is 700-1000°C, and the heat can be obtained by external heating, that is, by burning fuel outside the upstream pyrolysis reactor or passing heat Flue gas is used to provide the heat required for the reaction, and it can be obtained by self-heating, that is, by introducing a part of oxygen/air into the reactor and reacting with the reaction raw materials to maintain the heat released; the downstream tar cracking reactor The reaction temperature is 900-1300°C, which is maintained by the heat carried by the overflow material from the upstream and the heat released by the reaction between the oxygen-containing oxidation atmosphere and the semi-coke. The specific reaction temperature above can be adjusted according to different reaction raw materials.

According to the pyrolysis gasification method of the present invention, the pyrolysis gas obtained in step 2) is subjected to gas-solid separation; after the pyrolysis semi-coke obtained in step 2) is quenched, waste heat is recovered. Specifically, it can be connected with the coke quenching device 8 during the semi-coke discharge process, generate high-temperature and high-pressure steam through heat exchange, recover the heat carried by the semi-coke, and reduce the temperature of the semi-coke.

According to the pyrolysis gasification method of the present invention, an appropriate amount of calcium-based minerals or other minerals or catalysts capable of cracking tar can be added to the pyrolysis raw material.

The pyrolysis gasification method for preparing tar-free hydrogen-rich gas of the present invention can be carried out under normal pressure or under pressurized conditions.

The pyrolysis gasification device of the present invention based on the above-mentioned pyrolysis gasification method for preparing tar-free hydrogen-rich gas includes a feeding device 1, an overflow pipe 3, and also includes an upstream pyrolysis reactor 2 and a downstream tar cracking reactor 4 , the two communicate through the overflow pipe 3, and the feed device 1 communicates with the upstream pyrolysis reactor 2.

According to the pyrolysis gasification device of the present invention, the upstream pyrolysis reactor is preferably a rotary kiln, a fluidized bed or a dilute-phase conveying bed; the downstream tar cracking reactor is preferably a rotary kiln, a dilute-phase conveying bed, and a settling furnace or fixed bed.

According to the pyrolysis gasification device of the present invention, it can also include a cyclone separator 5, a dipleg 6, a coke discharge pipe 7 and a coke quenching device 8, and the coke discharge pipe 7 is connected with the downstream tar cracking reactor 4 and the coke quenching device respectively. 8 is connected, the upper material inlet of the cyclone separator 5 is connected with the coke quenching device 8 through a pipeline, and the solid product outlet at the bottom of the cyclone separator 5 is connected with the solid product collection device through the dipleg 6 .

Based on the above-mentioned pyrolysis gasification device, the following methods can be preferred:

The upstream pyrolysis reactor may be the first rotary kiln reactor 13 , and the downstream tar cracking reactor is the second rotary kiln reactor 14 .

The upstream pyrolysis reactor may be a fluidized bed 10 , and the downstream tar cracking reactor is a second rotary kiln reactor 14 . Further, the fluidized bed 10 can also be connected with several second rotary kiln reactors 14 to form a device group.

The upstream pyrolysis reactor can be a dilute phase transport bed 11 , and the downstream tar cracking reactor is a second rotary kiln reactor 14 .

On the basis of the above-mentioned device including cyclone separator 5, dipleg 6, coke discharge pipe 7 and coke quenching device 8, it may also only include cyclone separator 5, dipleg 6, coke quenching device 8, and said cyclone separator 5 The upper material inlet communicates with the downstream tar cracking reactor 4 through a pipeline, and the solid product outlet at the bottom of the cyclone separator 5 communicates with a coke quenching device 8 through a dipleg 6 .

Based on the above-mentioned pyrolysis gasification device, the following methods can be preferred:

The upstream pyrolysis reactor is a fluidized bed 10, and the downstream tar cracking reactor may be a dilute-phase transport bed 11.

The upstream pyrolysis reactor is a fluidized bed 10 , and the downstream tar cracking reactor may be a settling furnace 12 .

Further, it may be preferred that the gas outlet at the lower part of the side wall of the settling furnace 12 communicates with the inlet of the cyclone separator 5 , and the bottom of the settling furnace 12 directly communicates with the coke quenching device 8 .

In the above pyrolysis gasification method and pyrolysis gasification device for preparing tar-free hydrogen-rich gas, the feeding device 1 is preferably a screw feeding device.

The main idea of the present invention is to first extract the volatile matter in the carbon-containing solid fuel by pyrolysis, and then further remove the tar in the pyrolysis gas, partially gasify the semi-coke, and adjust the composition of the pyrolysis atmosphere The reactions are coupled together to increase the content of high-quality components (H ₂ , CH _{4 ,} etc.) in the pyrolysis gas and reduce the load of the subsequent conversion treatment process. The heat required for the entire reaction can be provided by the pyrolysis semi-char combustion of the by-product. The invention avoids the problems of burning volatile matter while fuel combustion provides heat in the traditional process, resulting in low content of H ₂ and CH ₄ in the pyrolysis gas, and large processing capacity of subsequent gas composition reforming reaction.

Description of drawings

Fig. 1 is the schematic diagram of pyrolysis gasification device of the present invention

Fig. 2 is the combined pyrolysis gasification device schematic diagram of two-stage rotary kiln of the present invention;

Fig. 3 is a schematic diagram of a pyrolysis gasification device with hot flue gas as a heat source in combination with two-stage rotary kilns of the present invention;

Fig. 4 is the pyrolysis gasification device schematic diagram that fluidized bed of the present invention combines with rotary kiln;

Fig. 5 is the schematic diagram of the pyrolysis gasification device combining the fluidized bed and a plurality of rotary kilns of the present invention;

Fig. 6 is a schematic diagram of a pyrolysis gasification device combining a dilute-phase conveying bed and a rotary kiln of the present invention;

Fig. 7 is a schematic diagram of a pyrolysis gasification device combining a fluidized bed and a dilute-phase conveying bed according to the present invention;

Fig. 8 is a schematic diagram of a pyrolysis gasification device combining a fluidized bed and a settling furnace according to the present invention;

Reference sign

1. Feeding device 2. Upstream pyrolysis reactor 3. Overflow pipe

4. Downstream tar cracking reactor 5. Cyclone separator 6. Die leg

7. Coke discharge tube 8. Coke quenching device 9. Burner

10. Fluidized bed 11. Dilute phase conveying bed 12. Settling furnace

13. The first rotary kiln reactor 14. The second rotary kiln reactor

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The pyrolysis gasification method for preparing tar-free hydrogen-rich gas of the present invention comprises the following steps:

1) The carbon-containing solid raw material is sent into the upstream pyrolysis reactor through the feeding device for pyrolysis to produce pyrolysis gas phase products and solid products;

2) The pyrolysis gas phase products and solid products produced in step 1) are passed into the downstream tar cracking reactor, and the tar is removed through high-temperature pyrolysis, partial oxidation and pyrolysis semi-coke catalytic cracking reactions to obtain pyrolysis gas and pyrolysis semi-coke. coke.

The upstream pyrolysis reactor can be a rotary kiln, a fluidized bed or a dilute phase transport bed. The above-mentioned downstream tar cracking reactor can be a rotary kiln, a dilute phase conveying bed, a settling furnace or a fixed bed.

The carbon-containing solid raw material is coal, biomass or other carbon-containing solid wastes.

The reaction temperature in the upstream pyrolysis reactor is 700-1000°C, and the reaction temperature in the downstream tar cracking reactor is 900-1300°C.

Further preferably, the pyrolysis gas obtained in step 2) is subjected to gas-solid separation; the pyrolysis semi-coke obtained in step 2) is quenched by dry method, and waste heat is recovered.

The pyrolysis gasification device of the present invention based on the above-mentioned pyrolysis gasification method for preparing tar-free hydrogen-rich gas, as shown in Figure 1, includes a feeding device 1, an overflow pipe 3, and also includes an upstream pyrolysis reactor 2 and The downstream tar cracking reactor 4 communicates with the upstream pyrolysis reactor 2 through the overflow pipe 3 .

The above-mentioned upstream pyrolysis reactor is preferably a rotary kiln, a fluidized bed or a dilute-phase conveying bed; the above-mentioned downstream tar cracking reactor is preferably a rotary kiln, a dilute-phase conveying bed, a settling furnace or a fixed bed.

The carbon-containing solid fuel is fed into the upstream pyrolysis reactor 2 through the feeding device 1 for pyrolysis. The pyrolysis semi-coke produced passes through the overflow pipe 3 together with the pyrolysis gas phase products, and enters the downstream tar cracking reactor 4. In the downstream tar cracking reactor 4, the pyrolysis tar is pyrolyzed at high temperature, partially oxidized and pyrolyzed The semi-coke is removed under the joint action of catalytic cracking, so that a large amount of high-quality pyrolysis gas can be obtained.

Preferably, the above-mentioned pyrolysis gasification device can also include a cyclone separator 5, a dipleg 6, a coke discharge pipe 7 and a coke quenching device 8, and the coke discharge pipe 7 is connected with the downstream tar cracking reactor 4 and the coke quenching device 8 respectively. The upper material inlet of the cyclone separator 5 is connected with the coke quenching device 8 through a pipeline, and the solid product outlet at the bottom of the cyclone separator 5 is connected with the solid product collection device through a dipleg 6 .

The carbon-containing solid fuel is fed into the upstream pyrolysis reactor 2 through the feeding device 1 for pyrolysis. The pyrolysis semi-coke produced passes through the overflow pipe 3 together with the pyrolysis gas phase products, and enters the downstream tar cracking reactor 4. In the downstream tar cracking reactor 4, the pyrolysis tar is pyrolyzed at high temperature, partially oxidized and pyrolyzed The semi-coke is removed under the joint action of catalytic cracking, so that a large amount of high-quality pyrolysis gas can be obtained. The generated gas passes through the cyclone separator 5 for gas-solid separation, and the obtained semi-coke passes through the coke discharge pipe 7 and enters the coke quenching device 8 for coke quenching treatment.

Further, on the basis of the above-mentioned device including the cyclone separator 5, the dipleg 6, the coke discharge tube 7 and the coke quenching device 8, it may also only include the cyclone separator 5, the dipleg 6, and the coke quenching device 8, the The upper material inlet of the cyclone separator 5 communicates with the downstream tar cracking reactor 4 through a pipeline, and the solid product outlet at the bottom of the cyclone separator 5 communicates with the coke quenching device 8 through a dipleg 6 .

The carbon-containing solid fuel is fed into the upstream pyrolysis reactor 2 through the feeding device 1 for pyrolysis. The pyrolysis semi-coke passes through the overflow pipe 3 together with the pyrolysis gas phase products, and enters the downstream tar cracking reactor 4 for reaction. The generated gas-solid mixture enters the cyclone separator 5 for gas-solid separation, and the obtained pyrolysis semi-coke enters the coke quenching device 8 for coke quenching treatment.

Example 1

The schematic diagram of the pyrolysis gasification device combined with two-stage rotary kiln reactors in this embodiment is shown in Figure 2, including a feeding device 1, a first rotary kiln reactor 13, a second rotary kiln reactor 14, and a coke quenching device 8. Cyclone separator 5 and material leg 6, etc.

When using this pyrolysis gasification device to prepare tar-free hydrogen-rich gas, carbon-containing solid fuel (such as coal) with a particle size of <20mm is sent to the upstream first rotary kiln through the feeding device 1 (such as a screw feeder) Pyrolysis is carried out at 700-900°C in the reactor 13, and the generated mixed gas and solid products enter the downstream second rotary kiln reactor 14 through the overflow pipe 3. A certain amount of oxygen, water vapor and other gases are introduced into the second rotary kiln reactor 14 and maintained at 1100°C. In the second rotary kiln reactor 14, the thermal cracking and partial oxidation of the pyrolytic tar mainly occur, and the catalytic cracking of the semi-coke to the pyrolytic tar is used to remove the tar; at the same time, the partial gasification of the pyrolytic coke occurs, thereby obtaining a large amount of High quality pyrolysis gas. The reacted product gas and pyrolysis semi-coke enter the coke quenching device 8 through the coke discharge pipe 7, and the obtained semi-coke can be used for industrial production after coke quenching treatment. The gasification gas obtained after the gas-solid separation of the product gas through the cyclone separator 5 is used for industrial production and civil use. The solid product separated by the cyclone separator 5 enters the solid product collecting device through the dipleg 6 .

Using Xilinhot coal with a particle size of less than 5mm as raw material, the experiment was carried out on an experimental device with an experimental treatment capacity of 50kg/h. The H ₂ /CO=2.3 in the obtained gas and the tar content reached 30mg/Nm ³ . The calorific value of the gas reaches 2300kcal/Nm ³ .

Example 2

The schematic diagram of the pyrolysis gasification device of this embodiment is shown in Figure 3. In this embodiment, a burner 9 is added outside the first rotary kiln reactor 13 in the upstream described in Embodiment 1, and the hot flue gas is used as the first The heat source of rotary kiln reactor 13, others are with embodiment 1.

Example 3

The schematic diagram of the combined fluidized bed and rotary kiln reactor pyrolysis gasification device in this embodiment is shown in Figure 4, including a feeding device 1, a fluidized bed 10, a second rotary kiln reactor 14, and a coke quenching device 8 , Cyclone separator 5 and material leg 6 etc.

When using the pyrolysis gasification device to prepare tar-free hydrogen-rich gas, the carbon-containing solid fuel with a particle size of <20mm is fed into the fluidized bed reactor 10 through the feeding device 1 and pyrolyzed at 700-1000°C to produce The mixed gas and solid products enter the downstream second rotary kiln reactor 14 through the overflow pipe 3. A certain amount of oxygen, water vapor and other gases are introduced into the second rotary kiln reactor 14 and maintained at 1300°C. In the second rotary kiln reactor 14, the thermal cracking and partial oxidation of the pyrolytic tar mainly occur, and the catalytic cracking of the semi-coke to the pyrolytic tar is used to remove the tar; at the same time, the partial gasification of the pyrolytic coke occurs, thereby obtaining a large amount of High quality pyrolysis gas. The reacted product gas and pyrolysis semi-coke enter the coke quenching device 8 through the coke discharge pipe 7, and the obtained semi-coke can be used for industrial production after coke quenching treatment. The gasification gas obtained after the gas-solid separation of the product gas through the cyclone separator 5 is used for industrial production and civil use. The solid product separated by the cyclone separator 5 enters the solid product collecting device through the dipleg 6 .

Example 4

The schematic diagram of the pyrolysis gasification device combined with a fluidized bed and a plurality of rotary kiln reactors in this embodiment is shown in Figure 5, which includes a feeding device 1, a fluidized bed 10, a second rotary kiln reactor 14, a Coke device 8, cyclone separator 5 and dipleg 6. The specific process of treating the reaction materials is similar to that of Example 3, except that a plurality of second rotary kiln reactors 14 are connected with the fluidized bed 10 to form a device group, which increases the processing capacity and improves the processing efficiency.

Example 5

The schematic diagram of the pyrolysis gasification device combined with the dilute-phase conveying bed and the rotary kiln reactor of this embodiment is shown in Figure 6, which includes a feeding device 1, a dilute-phase conveying bed 11, a second rotary kiln reactor 14, and a Coke device 8, cyclone separator 5 and dipleg 6, etc.

When the pyrolysis gasification device is used to prepare tar-free hydrogen-rich gas, several feeders 1 of carbon-containing solid fuels with a particle size of <5mm are fed into the dilute-phase conveying bed 11 for pyrolysis at 700-900°C to produce The mixed gas and solid products enter the downstream second rotary kiln reactor 14 through the overflow pipe 3. A certain amount of oxygen, water vapor and other gases are introduced into the second rotary kiln reactor 14 and maintained at 1100°C. In the second rotary kiln reactor 14, the thermal cracking and partial oxidation of the pyrolytic tar mainly occur, and the catalytic cracking of the semi-coke to the pyrolytic tar is used to remove the tar; at the same time, the partial gasification of the pyrolytic coke occurs, thereby obtaining a large amount of High quality pyrolysis gas. The reacted product gas and pyrolysis semi-coke enter the coke quenching device 8 through the coke discharge pipe 7, and the obtained semi-coke can be used for industrial production after coke quenching treatment. The gasification gas obtained after the gas-solid separation of the product gas through the cyclone separator 5 is used for industrial production and civil use. The solid product separated by the cyclone separator 5 enters the solid product collecting device through the dipleg 6 .

Example 6

The schematic diagram of the pyrolysis gasification device combining the fluidized bed and the dilute-phase conveying bed in this embodiment is shown in Figure 7, including a feeding device 1, a fluidized bed 10, a dilute-phase conveying bed 11, a coke quenching device 8, a cyclone Separator 5 and material leg 6 etc.

When using the pyrolysis gasification device to prepare tar-free hydrogen-rich gas, the carbon-containing solid fuel with a particle size of <20mm is fed into the fluidized bed 10 through the feeding device 1, and is pyrolyzed at 700-900°C to produce The mixed gas and solid product enter the dilute-phase conveying bed 11 through the overflow pipe 3. A certain amount of oxygen, water vapor and other gases are introduced into the dilute-phase transport bed 11 and maintained at 1100°C. In the dilute-phase conveying bed 11, the thermal cracking and partial oxidation of the pyrolytic tar mainly occurs, and the catalytic cracking of the semi-coke to the pyrolytic tar is used to remove the tar; at the same time, the partial gasification of the pyrolytic coke occurs, thereby obtaining a large amount of high-quality pyrolysis gas. The gasification gas and pyrolysis semi-coke obtained after the reacted product gas and pyrolysis semi-coke are separated from gas to solid by the cyclone separator 5 can be used for industrial production and civil use. The solid product separated by the cyclone separator 5 enters the coke quenching device 8 through the dipleg 6, and can be used for industrial production after coke quenching treatment.

Using Xilinhot coal with a particle size of 0.5-1.5mm as raw material, the experimental device with an experimental treatment capacity of 50kg/h is used for research. The H ₂ /CO=2 in the gas obtained, and the tar content reaches 50mg/Nm ³ . The calorific value of gas reaches 1500kcal/Nm ³ .

Example 7

The schematic diagram of the combined pyrolysis and gasification device of the fluidized bed and the settling furnace reactor of this embodiment is shown in Figure 8, including a feeding device 1, a fluidized bed 10, a settling furnace 12, a coke quenching device 8, and a cyclone separation device. Device 5 and material leg 6 etc.

When using the pyrolysis gasification device to prepare tar-free hydrogen-rich gas, the carbon-containing solid fuel with a particle size of <20 mm is fed into the fluidized bed 10 through the screw feeder 1 and pyrolyzed at 700-900 ° C to produce The mixed gas and solid products enter into the settling furnace 12 through the overflow pipe 3 . A certain amount of oxygen, water vapor and other gases are introduced into the settling furnace 12 and maintained at 1100°C. In the settling furnace 12, the thermal cracking and partial oxidation of the pyrolysis tar mainly occurs, and the catalytic cracking of the semi-coke to the pyrolysis tar is performed to remove the tar; at the same time, the partial gasification of the pyrolysis coke occurs, thereby obtaining a large amount of high-quality pyrolysis gas. The pyrolysis semi-coke after the reaction directly enters the coke quenching device 8 from the settling furnace 12, and the obtained semi-coke can be used for industrial production after coke quenching treatment. The gasification gas obtained after the gas-solid separation of the product gas through the cyclone separator 5 is used for industrial production and civil use. The solid product separated by the cyclone separator 5 enters the coke quenching device 8 through the dipleg 6, and can be used for industrial production after coke quenching treatment.

It should be pointed out that for the specific implementation method of the present invention, such as different organizational forms of the reactor, the reaction atmosphere, etc. can be improved according to specific actual needs; Under carry out; A certain amount of calcium-based minerals or other minerals or catalysts with tar cracking ability can be added in the reaction raw materials, all of which do not violate the main idea of the present invention.

Claims (5)

1. A pyrolysis gasification method for preparing tar-free hydrogen-rich gas, comprising the following steps: 1) Send the carbon-containing solid raw material into the upstream pyrolysis reactor through the feeding device for aerobic pyrolysis to produce pyrolysis gas phase products and solid products; 2) Pass the pyrolysis gas phase products and solid products produced in step 1) into the downstream tar cracking reactor, and remove the tar through high-temperature pyrolysis, partial oxidation and pyrolysis semi-coke catalytic cracking reaction; to obtain pyrolysis gas and pyrolysis semi-coke; Wherein, the reaction temperature in the upstream pyrolysis reactor is 700-1000°C; the reaction temperature in the downstream tar cracking reactor is 900-1300°C, through the heat carried by the overflow material from the upstream and the oxygen-containing oxidation atmosphere It is maintained by the heat released by the reaction with semi-coke. 2. The pyrolysis gasification method according to claim 1, characterized in that, the carbon-containing solid raw material is coal, biomass or carbon-containing solid waste. 3. The pyrolysis gasification method according to claim 1 or 2, characterized in that the pyrolysis product obtained in step 2) is subjected to gas-solid separation; and pyrolysis gas and pyrolysis semi-coke products are obtained. 4. The pyrolysis gasification method according to claim 1 or 2, characterized in that a certain amount of calcium-based minerals or other catalysts with tar cracking capacity are added to the pyrolysis raw material. 5. a pyrolysis gasification device based on the pyrolysis gasification method for preparing tar-free hydrogen-rich gas according to claim 1, comprising feeding device (1), overflow pipe (3), upstream pyrolysis reactor ( 2), the feed device (1) is communicated with the upstream pyrolysis reactor (2), it is characterized in that, also includes the downstream tar cracking reactor (4), through the overflow pipe (3) and the upstream pyrolysis reactor (2) connectivity; Wherein, also comprise cyclone separator (5), dipleg (6), coke discharge pipe (7) and coke quenching device (8), described coke discharge pipe (7) is connected with downstream tar cracking reactor (4) and The coke quenching device (8) is connected, the upper material inlet of the cyclone separator (5) is connected with the coke quenching device (8) through a pipeline, and the solid product outlet at the bottom of the cyclone separator (5) is connected to the solid product through the material leg (6). Product collection device connected; Or, also include cyclone separator (5), dipleg (6), and coke quenching device (8), described cyclone separator (5) upper material inlet is communicated with downstream tar cracking reactor (4) through pipeline, The solid product outlet at the bottom of the cyclone separator (5) communicates with the coke quenching device (8) through the dipleg (6); Wherein, the upstream pyrolysis reactor is a rotary kiln, a fluidized bed or a dilute phase conveying bed; Wherein, the downstream tar cracking reactor is a rotary kiln, a dilute phase conveying bed, a settling furnace or a fixed bed.