Method for preparing biochar by continuous thermal cracking of biomass using self-heating method

Abstract

The present invention discloses a method for preparing biochar by continuous thermal cracking of self-heating biomass, which relates to the field of biomass energy technology. The method comprises a batcher, a raw material preprocessor, a tempering reactor, a self-heating diverter, a primary inerter, a secondary inerter and a steam generator. The outlet of the batcher is connected to the material inlet of the raw material preprocessor through a feeding belt, the material outlet of the raw material preprocessor is connected to the material inlet of the tempering reactor through a feeding belt, and the front-end flue gas outlet of the tempering reactor is connected to the inlet of the self-heating diverter. The present invention designs a biomass thermal cracking production line from both the material flow and flue gas flow aspects. There are no problems such as material blockage and racking in the biomass raw material transportation process. The quality of the biochar product is stable and the output is continuous and stable. While the heat supply of the process system is self-satisfied, the surplus heat is sold in the form of steam shipment, thereby realizing comprehensive and efficient utilization of the system heat.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass energy, and in particular to a method for preparing biochar by continuous self-heating biomass thermal cracking. Background Art

[0002] In my country's energy consumption structure, fossil energy such as coal still accounts for a large proportion.

[0003] The technical routes for producing biochar from biomass raw materials include biological fermentation, hydrothermal conversion, and thermochemical conversion. Among them, thermochemical conversion has the greatest value for industrial promotion. According to market research, the industrial production process for producing biochar from biomass pyrolysis previously mainly used the form of smoldering in earthen kilns: the biomass raw materials were heated and converted in a closed space, and over a period of several days to dozens of days, they were slowly converted into biochar products. In recent years, a continuous biochar production process has gradually developed. However, due to the limitations of technological development and the process of biomass pyrolysis, the scale of biochar production has always been small and cannot meet the large-scale production needs of large industries.

[0004] For the industrial production of biochar, urgent challenges include heat conduction issues in biomass feedstock (which is a poor conductor of heat), efficient handling of combustible gases from biomass pyrolysis, energy balance issues in the production process system, and unstable biomass feedstock supply. Based on these issues, a self-heating method for producing biochar through continuous biomass pyrolysis is proposed. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems in the prior art and to propose a method for preparing biochar by continuous pyrolysis of self-heating biomass.

[0006] A method for preparing biochar by continuous thermal cracking of self-heating biomass includes a batcher, a raw material preprocessor, a conditioning reactor, an autothermal diverter, a primary inerter, a secondary inerter and a steam generator, wherein the outlet of the batcher is connected to the material inlet of the raw material preprocessor via a feeding belt, the material outlet of the raw material preprocessor is connected to the material inlet of the conditioning reactor via a loading belt, the front end flue gas outlet of the conditioning reactor is connected to the inlet of the autothermal diverter, the outlet of the autothermal diverter is connected to the inlet of the steam generator, the flue gas inlet of the raw material preprocessor is connected to the outlet of the steam generator and the rear end flue gas outlet of the conditioning reactor, the flue gas inlet of the conditioning reactor is connected to the outlet of the autothermal diverter and the rear end flue gas outlet of the conditioning reactor, the material outlet of the conditioning reactor is connected to the inlet of the primary inerter, the outlet of the primary inerter is connected to the inlet of the secondary inerter, and the outlet of the secondary inerter is connected to a finished product bin.

[0007] Preferably, the flue gas outlet of the raw material preprocessor is connected to a cyclone dust collector, the flue gas outlet of the cyclone dust collector is connected to a bag dust collector, and the dust exhaust outlet of the cyclone dust collector is connected to a feeding belt.

[0008] Preferably, the batcher consists of a plurality of batching bins.

[0009] Preferably, the material transportation between the conditioning reactor, the primary inerter, the secondary inerter and the finished product bin is carried out by reamer conveying.

[0010] Preferably, the steps include:

[0011] S1. Biomass materials are unloaded from the batcher and conveyed by the feed belt to the raw material preprocessor for pretreatment to remove most of the moisture in the raw materials. The flue gas discharged from the tail of the preprocessor is filtered and dust-removed by the cyclone dust collector and bag dust collector before being discharged through the chimney;

[0012] S2. The pretreated biomass material and the dust generated in the cyclone dust collector are transported to the tempering reactor through a feeding belt, where a thermal cracking conversion process occurs to generate the main product biochar and the by-product combustible gas;

[0013] S3. The combustible gas produced as a byproduct of thermal cracking in the conditioning reactor is discharged from the front end of the conditioning reactor and directly enters the autothermal splitter for full combustion, generating high-temperature flue gas. A portion of the low-temperature flue gas discharged from the tail end of the conditioning reactor is mixed with a portion of the high-temperature flue gas in the autothermal splitter, and the two flue gases are mixed to serve as a heat source for the conditioning reactor;

[0014] S4. The excess high-temperature flue gas in the self-heating splitter is converted into steam by the steam generator. The low-temperature flue gas at the steam generator outlet is mixed with the remaining circulating flue gas from the quenching and tempering reactor to form flue gas with suitable temperature to be supplied to the raw material preprocessor;

[0015] S5. The biochar is output from the rear end of the conditioning reactor, cooled to room temperature by the subsequent first-stage inerting device and the second-stage inerting device, and then stored in the finished product warehouse.

[0016] Preferably, in step S4, the temperature of the flue gas after mixing is less than 350°C.

[0017] Preferably, in step S5, the residence time of the biochar in the primary inerting device and the secondary inerting device is greater than 10 minutes and 8 hours respectively, and the temperature of the biochar entering the finished product bin is less than 30°C.

[0018] Compared with the existing technology, the advantages of the present invention are:

[0019] The present invention designs the biomass pyrolysis production line from both the material flow and flue gas flow aspects. There are no problems such as material blockage and racking in the biomass raw material transportation process. The quality of the biomass charcoal product is stable and the output is continuous and stable. While the heat supply of the process system is self-sufficient, the surplus heat is sold in the form of steam shipment, realizing comprehensive and efficient utilization of the system's heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0022] Reference Figure 1 As shown, a method for preparing biochar by continuous thermal cracking of self-heating biomass includes a batcher, a raw material preprocessor, a tempering reactor, an autothermal diverter, a primary inerter, a secondary inerter and a steam generator. The outlet of the batcher is connected to the material inlet of the raw material preprocessor through a feeding belt, the material outlet of the raw material preprocessor is connected to the material inlet of the tempering reactor through a loading belt, the front end flue gas outlet of the tempering reactor is connected to the inlet of the autothermal diverter, the outlet of the autothermal diverter is connected to the inlet of the steam generator, the flue gas inlet of the raw material preprocessor is connected to the outlet of the steam generator and the rear end flue gas outlet of the tempering reactor, the flue gas inlet of the tempering reactor is connected to the outlet of the autothermal diverter and the rear end flue gas outlet of the tempering reactor, the material outlet of the tempering reactor is connected to the inlet of the primary inerter, the outlet of the primary inerter is connected to the inlet of the secondary inerter, and the outlet of the secondary inerter is connected to a finished product bin.

[0023] The flue gas outlet of the raw material preprocessor is connected to a cyclone dust collector, the flue gas outlet of the cyclone dust collector is connected to a bag dust collector, and the dust exhaust outlet of the cyclone dust collector is connected to a feeding belt.

[0024] The batcher is composed of multiple batching bins, which are distributed in different batching bins according to different types or characteristics of raw materials. The use of batching bins can realize the matching of different types of raw materials on the one hand, and on the other hand, it can better solve the instability of biomass raw materials.

[0025] The material transportation between the conditioning reactor, the first-stage inerter, the second-stage inerter and the finished product warehouse adopts the reamer conveying method, which adopts the reamer forced conveying method without adding a transition warehouse in the middle to avoid the bridging and other blockage phenomena caused by material accumulation.

[0026] The following steps are involved:

[0027] S1. Biomass materials are unloaded from the batcher and conveyed by the feed belt to the raw material preprocessor for pretreatment to remove most of the moisture in the raw materials. The flue gas discharged from the tail of the preprocessor is filtered and dust-removed by the cyclone dust collector and bag dust collector before being discharged through the chimney;

[0028] S2. The pretreated biomass material and the dust generated in the cyclone dust collector are transported to the tempering reactor through a feeding belt, where a thermal cracking conversion process occurs to generate the main product biochar and the by-product combustible gas;

[0029] S3. The combustible gas produced as a byproduct of thermal cracking in the conditioning reactor is discharged from the front section of the conditioning reactor and directly enters the autothermal splitter for complete combustion (to avoid condensation of tar in the combustible gas), generating high-temperature flue gas. Part of the low-temperature flue gas discharged from the tail section of the conditioning reactor is mixed with part of the high-temperature flue gas in the autothermal splitter, and the two flue gases are mixed to serve as the heat source for the conditioning reactor;

[0030] S4. The excess high-temperature flue gas in the self-heating splitter is passed through a steam generator to convert heat into steam (the generated steam can be sold externally). The low-temperature flue gas at the steam generator outlet is mixed with part of the recycled flue gas from the conditioning reactor to form flue gas with a suitable temperature to be supplied to the raw material preprocessor;

[0031] S5. The biochar is output from the rear end of the conditioning reactor, cooled to room temperature by the subsequent first-stage inerting device and the second-stage inerting device, and then stored in the finished product warehouse.

[0032] In step S4, the temperature of the flue gas after mixing is less than 350° C. The flue gas temperature of the raw material preprocessor should not be too high, otherwise it will easily cause material combustion or premature thermal cracking reaction.

[0033] The residence time of the biochar in the primary inerter and the secondary inerter is greater than 10 minutes and 8 hours respectively, and the temperature of the biochar entering the finished product bin is less than 30°C.

[0034] Example

[0035] Taking a feed rate of 4 tons per hour as an example, the biomass feedstock resides in the pre-processor for 50 minutes, reducing its moisture content from 30% to 10%. The biomass feedstock resides in the upgrading reactor for 35 minutes, achieving a biochar yield of 41%. The biochar product resides in the primary inerting vessel for 15 minutes and the secondary inerting vessel for 10 hours. The finished charcoal enters the warehouse at a temperature of 25°C.

[0036] The amount of high-temperature flue gas generated in the self-heating distributor is 13280m 3 / h, the flue gas temperature is 1100℃, the original moisture of the biomass material is 30%, and the moisture after the raw material preprocessor is 10%. When the flue gas temperature at the inlet of the raw material preprocessor is 270℃ and the outlet temperature is 110℃, the flue gas volume per hour is 13280m 3 The heat abundance of the raw material preprocessor is 226,362 kJ / h, which can realize the pretreatment process of biomass raw materials. The circulating air volume of the upgrading reactor is 39200 m 3 / h, the inlet flue gas temperature is 503℃, the outlet flue gas temperature is 350℃, and the amount of combustible gas generated during the upgrading reaction is 5280m 3 / h.

[0037] In summary, the present invention designs and develops a production process for preparing biochar by thermal cracking of biomass in terms of both material flow and flue gas flow. On the one hand, the material conveying equipment is adapted to the characteristics of biomass materials to ensure the passability of material conveying. On the other hand, the cascade utilization of flue gas heat realizes the comprehensive utilization of the system's surplus heat while the system's heat is self-satisfied.

[0038] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

Claims

1. A method for preparing biochar by continuous pyrolysis of biomass using self-heating method, characterized by: It includes a batcher, a raw material preprocessor, a conditioning reactor, an autothermal diverter, a primary inerter, a secondary inerter and a steam generator, the outlet of the batcher is connected to the material inlet of the raw material preprocessor through a feeding belt, the material outlet of the raw material preprocessor is connected to the material inlet of the conditioning reactor through a loading belt, the front end flue gas outlet of the conditioning reactor is connected to the inlet of the autothermal diverter, the outlet of the autothermal diverter is connected to the inlet of the steam generator, the flue gas inlet of the raw material preprocessor is connected to the outlet of the steam generator and the rear end flue gas outlet of the conditioning reactor, the flue gas inlet of the conditioning reactor is connected to the outlet of the autothermal diverter and the rear end flue gas outlet of the conditioning reactor, the material outlet of the conditioning reactor is connected to the inlet of the primary inerter, the outlet of the primary inerter is connected to the inlet of the secondary inerter, and the outlet of the secondary inerter is connected to a finished product bin; The flue gas outlet of the raw material preprocessor is connected to a cyclone dust collector, the flue gas outlet of the cyclone dust collector is connected to a bag dust collector, and the dust outlet of the cyclone dust collector is connected to a feeding belt; The following steps are involved: S1. Biomass materials are unloaded from the batcher and transported by the feed belt to the raw material preprocessor for pretreatment to remove most of the moisture in the raw materials. The flue gas discharged from the tail of the raw material preprocessor is filtered and dust-removed by the cyclone dust collector and bag dust collector before being discharged through the chimney; S2. The pretreated biomass material and the dust generated in the cyclone dust collector are transported to the tempering reactor through a feeding belt, where a thermal cracking conversion process occurs to generate the main product biochar and the by-product combustible gas; S3. The combustible gas produced as a byproduct of thermal cracking in the conditioning reactor is discharged from the front end of the conditioning reactor and directly enters the autothermal splitter for full combustion, generating high-temperature flue gas. A portion of the low-temperature flue gas discharged from the tail end of the conditioning reactor is mixed with a portion of the high-temperature flue gas in the autothermal splitter, and the two flue gases are mixed to serve as a heat source for the conditioning reactor; S4. The excess high-temperature flue gas in the self-heating splitter is converted into steam by the steam generator. The low-temperature flue gas at the steam generator outlet is mixed with part of the circulating flue gas from the conditioning reactor to form flue gas with suitable temperature, which is supplied to the raw material preprocessor. S5. The biochar is output from the rear end of the conditioning reactor, cooled to room temperature by the subsequent first-stage inerting device and the second-stage inerting device, and then stored in the finished product warehouse.

2. The method for preparing biochar by continuous self-heating biomass pyrolysis according to claim 1, characterized in that: The batcher consists of a plurality of batching bins.

3. The method for preparing biochar by continuous self-heating biomass pyrolysis according to claim 1, characterized in that: The material transportation between the conditioning reactor, the first-stage inerter, the second-stage inerter and the finished product bin is carried out by reamer conveying.

4. The method for preparing biochar by continuous self-heating biomass pyrolysis according to claim 1, characterized in that: In step S4, the temperature of the flue gas after mixing is less than 350°C.

5. The method for preparing biochar by continuous self-heating biomass pyrolysis according to claim 1, characterized in that: In step S5, the residence time of the biochar in the primary inerting device and the secondary inerting device is greater than 10 minutes and 8 hours respectively, and the temperature of the biochar entering the finished product bin is less than 30°C.

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