Metallurgy biomass charcoal preparation system and method

Abstract

The invention discloses a metallurgical biomass charcoal preparation system and method.The system comprises a biomass carbonization device, and a carbonized material outlet of the biomass carbonization device is sequentially connected with feed inlets of a charcoal smashing device, a premixing device and a granulation device; a combustible gas outlet of the biomass carbonization device is connected with a flue gas inlet of the primary combustion device, a discharge port of the granulation device and a flue gas outlet of the primary combustion device are both connected with an inlet of the quality improving device, and an outlet of the quality improving device is connected with an inlet of the carbon particle cooling device. The biomass charcoal prepared by the method has the characteristics of high mechanical strength and proper reaction activity, meets the requirements of a solid reducing agent for the metallurgical industry, can replace coal coke, and provides powerful support for carbon emission reduction in the metallurgical industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of biochar production, and in particular relates to a system and method for preparing biochar for metallurgy. Background Art

[0002] At present, the solid reducing agent used in the metallurgical industry is mainly coal-based coke. Under the global trend of carbon emission reduction, the metallurgical industry faces huge pressure to reduce carbon emissions. Biomass energy is recognized as the world's largest renewable energy source. From the industrial analysis of raw materials, its effective components are mainly volatile matter and fixed carbon. Fixed carbon can be used to prepare various carbon products to replace coal-based carbon. It has the advantages of cleanliness and low carbon and has good development prospects.

[0003] The existing methods of preparing biochar using biomass as raw materials have the problems of loose structure, and its strength and reactivity are difficult to meet the requirements of metallurgical charcoal compared to coal charcoal. The main reason why biochar has a looser structure than coal charcoal is that the carbon skeleton of the biomass itself is not strong enough and has a large porosity. Therefore, no matter what charcoal-making method is used for biomass, if its structure is not modified or strengthened, its mechanical strength will be difficult to meet the requirements of metallurgical charcoal; and because biochar has a large porosity and strong reactivity, it is very easy to react prematurely when used in the metallurgical industry, and cannot meet metallurgical requirements. The present invention develops a system and method for preparing biochar for metallurgy, which is intended to solve the problem that the mechanical strength and reactivity of the above-mentioned biochar are difficult to meet when used in the metallurgical industry. Summary of the invention

[0004] Technical problems to be solved: In view of the above technical problems, the present invention provides a system and method for preparing biochar for metallurgy, which can effectively solve the problem that the strength and reaction activity of the above biochar are difficult to meet when used in the metallurgical industry.

[0005] Technical solution: In the first aspect, the present invention provides a system for preparing biochar for metallurgy, comprising a biomass carbonization device, wherein the carbonized material outlet of the biomass carbonization device is connected to the feed inlets of a charcoal crushing device, a premixing device and a granulation device in sequence, the combustible gas outlet of the biomass carbonization device is connected to the flue gas inlet of a primary combustion device, the discharge port of the granulation device and the flue gas outlet of the primary combustion device are both connected to the inlet of a quality improvement device, and the outlet of the quality improvement device is connected to the inlet of a charcoal particle cooling device.

[0006] Preferably, the biomass carbonization device is a rotary kiln structure, comprising a device body and a feeding device, a front sealing cover is provided at one end of the device body, and a rear sealing cover is provided at the other end, and the outlet end of the feeding device extends through the front sealing cover to the interior of the device body; the feeding device and the device body are in an eccentric structure, and the distance between the center line of the feeding device outlet and the upper shell of the device body is greater than the distance between it and the lower shell.

[0007] Furthermore, the biomass carbonization device also includes a directional air supply device and a burner. The air duct of the directional air supply device runs through the device body, and a plurality of air distribution holes are opened on the side wall of the device body; the burner is connected to the rear sealing cover.

[0008] Preferably, the premixing device is provided with an inlet for a particle strengthening agent, and the premixing device is a jacket structure, the carbonized material and the particle strengthening agent are fully mixed in the inner cylinder, and the jacket is filled with a heat carrier.

[0009] Preferably, the upgrading device is a jacket structure, and the biochar particles are upgraded at high temperature in the inner cylinder. The jacket is filled with high-temperature flue gas generated by the primary combustion device, and the flow direction of the high-temperature flue gas is opposite to that of the biochar particles.

[0010] Preferably, the charcoal particle cooling device is a jacket structure, the biomass charcoal particles are cooled in the inner cylinder, the jacket contains a heat carrier, and the outlet of the heat carrier is connected to the jacket of the premixing device.

[0011] Preferably, the system further comprises a burnout and waste heat recovery device, a biomass drying device and a carbonized material cooling device, the flue gas inlet of the burnout and waste heat recovery device is respectively connected to the jacket flue gas outlet and the inner cylinder flue gas outlet of the upgrading device, the flue gas outlet of the burnout and waste heat recovery device is connected to the flue gas inlet of the biomass drying device, and the material outlet of the biomass drying device is connected to the material inlet of the biomass carbonization device; The smoke outlet of the biomass drying device is provided with a smoke treatment device; The feed inlet of the carbonized material cooling device is connected to the discharge port of the biomass carbonization device, and the discharge port of the carbonized material cooling device is connected to the feed inlet of the charcoal crushing device.

[0012] In a second aspect, the present invention provides a method for preparing metallurgical biochar using the system described in the first aspect, comprising the following steps: S1. Biomass is added to the biomass carbonization device, where a carbonization reaction occurs to generate carbonized material and combustible gas; the combustible gas is sent to the primary combustion device for incomplete combustion, and the generated high-temperature flue gas is sent to the jacket of the upgrading device; the carbonized material is cooled by the carbonized material cooling device and then sent to the charcoal crushing device for crushing; S2. The crushed carbonized material is fully mixed with the particle enhancer in the premixing device and heated by the heat carrier in the jacket. The resulting mixture is sent to the granulating device for granulation, and the generated biochar particles are sent to the upgrading device; S3, the biochar particles are solidified at high temperature in the upgrading device, and then sent to the carbon particle cooling device for cooling, and the obtained product is metallurgical biochar; S4. The flue gas generated by the quality improvement device and the flue gas in the jacket are sent to the combustion and waste heat recovery device to achieve the combustion of the combustible components in the flue gas. The flue gas is reduced to a suitable temperature by waste heat recovery and sent to the biomass drying device to dry the biomass. It is then treated by the flue gas treatment device and discharged after meeting the standards. The suitable temperature is 200-280°C.

[0013] Preferably, the combustion in the primary combustion device is incomplete combustion, and its excess oxygen coefficient is adjusted to control the temperature of the upgrading device to be maintained at 700-1050°C; the residence time of the biochar particles in the upgrading device is 30-150 minutes, and the residence time of the biochar particles in the charcoal particle cooling device is 10-60 minutes.

[0014] Preferably, the particle strengthener is a material that can fill the voids in the carbon particles and can enhance the strength of the carbon structure after high-temperature curing, and the mass ratio of the particle strengthener to the carbonized material is 1:(20-50).

[0015] Preferably, the granular strengthening agent is industrial starch, phenolic resin or wood tar.

[0016] Beneficial effects: 1) The feeding device and the device body of the biomass carbonization device are in an eccentric structure as a whole, which can increase the top space of the inner cylinder of the carbonization device, which is conducive to the combustible gas to promptly remove the dust carried in the biomass raw materials and reduce the impact on subsequent carbon products; 2) After adding a directional air distribution device, the high temperature zone in the carbonization device can be adjusted according to the specific position of the air distribution holes, so that the high temperature zone in the device can be controlled, thereby reducing the burning loss of fixed carbon and increasing the yield of carbonized materials; 3) The system is equipped with a primary combustion device and a burnout and waste heat recovery device. The combustible gas is first partially burned in the primary combustion device, and then sent to the burnout and waste heat recovery device for secondary combustion after meeting the heat demand of the upgrading device. At the same time, the flue gas generated in the inner cylinder of the upgrading device is burnt out, and the heat recovered by the burnout and waste heat recovery device is flexibly used according to specific needs; 4) The flue gas flow direction and the carbon particle flow direction in the quality improvement device are countercurrent, which can reduce the heating rate of the carbon particles and prevent the carbon particles from bursting and deforming due to rapid heating; 5) The benefits of connecting the heat carrier of the carbon particle cooling device and the premixing device are: the carbonized material and the particle strengthening agent need to be heated when mixed in the premixing device; the carbon particles need to be cooled slowly, and the temperature of the cooling medium needs to be appropriate. The heat carrier of the premixing device that releases heat is suitable as the heat absorbing medium of the carbon particle cooling device; 6) The biochar prepared by the present invention can be applied to the metallurgical industry because the pulverization of the biochar increases the specific surface area of ​​the carbonized material, and when the biochar is fully mixed with the particulate enhancer in the premixing device, the effective ingredients of the particulate enhancer can be fully adsorbed in the voids of the carbonized material, and the heating of the premixing device enhances the process; the mixture of the carbonized material and the particulate enhancer is extruded and heated by the granulating device to further improve the strength of the biochar; the biochar particles are subjected to high-temperature heat treatment in the quality improvement device, and the particulate enhancer fully acts and solidifies, which improves the strength of the biochar while reducing the porosity of the biochar, thereby achieving the requirements of high mechanical strength and suitable reaction activity of the biochar when applied to the metallurgical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a metallurgical biochar preparation system of the present invention; Figure 2 It is a side view of the biomass carbonization device of the present invention and a cross-sectional view along the AA direction; Serial numbers in the figure: 1. Biomass carbonization device, 101. Device body, 102. Front sealing cover, 103. Feeding device, 104. Rear sealing cover, 105. Burner, 106. Directional air supply device, 2. Carbonized material cooling device, 3. Carbon crushing device, 4. Premixing device, 5. Granulation device, 6. Primary combustion device, 7. Quality improvement device, 8. Burnout and waste heat recovery device, 9. Carbon particle cooling device, 10. Biomass drying device, 11. Flue gas treatment device. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments: Example 1

[0019] like Figure 1 As shown, a system for preparing biochar for metallurgy includes a biomass carbonization device 1, wherein the carbonized material outlet of the biomass carbonization device 1 is connected to the feed ports of a charcoal crushing device 3, a premixing device 4 and a granulation device 5 in sequence, the combustible gas outlet of the biomass carbonization device 1 is connected to the flue gas inlet of a primary combustion device 6, the discharge port of the granulation device 5 and the flue gas outlet of the primary combustion device 6 are both connected to the inlet of a quality improvement device 7, and the outlet of the quality improvement device 7 is connected to the inlet of a charcoal particle cooling device 9.

[0020] like Figure 2As shown: the above-mentioned biomass carbonization device 1 is a rotary kiln structure, and the biomass carbonization device 1 includes a device body 101 and a feeding device 103. A front sealing cover 102 is provided at one end of the device body 101, and a rear sealing cover 104 is provided at the other end. The outlet end of the feeding device 103 passes through the front sealing cover 102 and extends to the inside of the device body 101; the feeding device 103 and the device body 101 are in an eccentric structure, and the distance between the center line of the discharge port of the feeding device 103 and the upper shell of the device body 101 is greater than the distance between the center line of the discharge port of the feeding device 103 and the lower shell; the biomass carbonization device 1 also includes a directional air supply device 106 and a burner 105, the air duct of the directional air supply device 106 passes through the device body 101, and a plurality of air distribution holes are opened on the side wall of the device body 101; the burner of the burner 105 is arranged in the rear sealing cover 104.

[0021] The premixing device 4 is provided with an inlet for a particle strengthening agent. The premixing device 4 is a jacket structure. The carbonized material and the particle strengthening agent are fully mixed in the inner cylinder, and the jacket is filled with a heat carrier.

[0022] The upgrading device 7 is a jacket structure, and the biochar particles are upgraded at high temperature in the inner cylinder. The jacket is filled with high-temperature flue gas generated by the primary combustion device 6, and the flow direction of the high-temperature flue gas is opposite to that of the biochar particles.

[0023] The charcoal particle cooling device 9 is a jacket structure, the biomass charcoal particles are cooled in the inner cylinder, the jacket contains a heat carrier, and the outlet of the heat carrier is connected to the jacket of the premixing device 4 . Example 2

[0024] like Figure 1 As shown: a metallurgical biochar preparation system, based on Example 1, further includes a burnout and waste heat recovery device 8, a biomass drying device 10 and a carbonized material cooling device 2, the flue gas inlet of the burnout and waste heat recovery device 8 is respectively connected to the jacket flue gas outlet and the inner tube flue gas outlet of the upgrading device 7, the flue gas outlet of the burnout and waste heat recovery device 8 is connected to the flue gas inlet of the biomass drying device 10, and the material outlet of the biomass drying device 10 is connected to the material inlet of the biomass carbonization device 1; The smoke outlet of the biomass drying device 10 is provided with a smoke treatment device 11; The feed inlet of the carbonized material cooling device 2 is connected to the discharge port of the biomass carbonization device 1 , and the discharge port of the carbonized material cooling device 2 is connected to the feed inlet of the charcoal crushing device 3 . Example 3

[0025] The method for preparing metallurgical biochar using the system of Example 2, wherein the ratio of fixed carbon to ash in the biomass (dry basis) should be greater than 6, specifically comprises the following steps: S1. Add wood chips (with a basic moisture content of 13%, fixed carbon of 15.4%, volatile matter of 70.4% and ash of 1.2%) into a biomass carbonization device 1, where a carbonization reaction occurs to generate carbonized material and combustible gas; the combustible gas is sent to a primary combustion device 6 for incomplete combustion, and the generated high-temperature flue gas is sent to the jacket of a quality improvement device 7; the carbonized material is cooled by a carbonized material cooling device 2 and then sent to a charcoal crushing device 3 for crushing; S2, the crushed carbonized material is fully mixed with the particle enhancer in the premixing device 4 and heated by the heat carrier in the jacket, and the resulting mixture is sent to the granulating device 5 for granulation, and the generated biochar particles are sent to the upgrading device 7; S3, the biochar particles are cured at high temperature in the upgrading device 7, and then sent to the carbon particle cooling device 9 for cooling, and the obtained product is metallurgical biochar; S4, the flue gas generated by the quality improvement device 7 and the flue gas in the jacket are sent to the combustion and waste heat recovery device 8 to achieve the combustion of combustible components in the flue gas. After the waste heat is recovered, the flue gas is treated by the flue gas treatment device 11 and then discharged after meeting the standards.

[0026] The carbonization temperature is controlled at 550-620 °C, the carbonization time is controlled at 1 h, the combustion in the primary combustion device 6 is controlled to be incomplete combustion, and the temperature of the upgrading device 7 is controlled at 850 °C; the residence time of the biochar particles in the upgrading device 7 is 45 min, and the residence time of the biochar particles in the charcoal particle cooling device 9 is 20 min.

[0027] The particle strengthener is phenolic resin, and the mass ratio of phenolic resin to the biomass carbonized material is 1:42. Example 4

[0028] The method for preparing metallurgical biochar using the system of Example 2, wherein the ratio of fixed carbon to ash in the biomass (dry basis) should be greater than 6, specifically comprises the following steps: S1, wood chips (received basic moisture content of 35%, fixed carbon content of 11.4%, volatile matter of 52.5% and ash content of 1.1%) are dried to a moisture content of less than 20% and then added to a biomass carbonization device 1, where a carbonization reaction occurs to generate carbonized material and combustible gas; the combustible gas is sent to a primary combustion device 6 for incomplete combustion, and the generated high-temperature flue gas is sent to the jacket of a quality improvement device 7; the carbonized material is cooled by a carbonized material cooling device 2 and then sent to a charcoal crushing device 3 for crushing; S2, the crushed carbonized material is fully mixed with the particle enhancer in the premixing device 4 and heated by the heat carrier in the jacket, and the resulting mixture is sent to the granulating device 5 for granulation, and the generated biochar particles are sent to the upgrading device 7; S3, the biochar particles are cured at high temperature in the upgrading device 7, and then sent to the carbon particle cooling device 9 for cooling, and the obtained product is metallurgical biochar; S4, the flue gas generated by the upgrading device 7 and the flue gas in the jacket are sent to the combustion and waste heat recovery device 8 to achieve the combustion of combustible components in the flue gas. After the flue gas is reduced to 220°C by waste heat recovery, the biomass is dried by the biomass drying device 10, and then treated by the flue gas treatment device 11 to meet the standards before being discharged.

[0029] The carbonization temperature is controlled at 600-650 °C, the carbonization time is controlled at 1.2 h, the combustion in the primary combustion device 6 is controlled to be incomplete combustion, and the temperature of the upgrading device 7 is controlled at 800 °C; the residence time of the biochar particles in the upgrading device 7 is 35 min, and the residence time of the biochar particles in the charcoal particle cooling device 9 is 20 min.

[0030] The above-mentioned particle strengthener is a mixture of industrial starch and phenolic resin, and the mass ratio of the two is 1:0.4; the mass ratio of the strengthener mixture to the biomass carbonized material is 1:32.

[0031] Comparative Example The system described in Example 2 is used to prepare biomass carbonized material: wood chips (basic moisture content of 13%, fixed carbon content of 15.4%, volatile matter content of 70.4% and ash content of 1.2%) are added to the biomass carbonization device 1, where a carbonization reaction occurs to generate carbonized material and combustible gas; the carbonized material is cooled by the carbonized material cooling device 2 and then sent to the carbon crushing device 3 for crushing, and then sent to the granulation device 5 for granulation to obtain biomass carbonized material particles, which are naturally dried. The carbonization temperature and time are consistent with those in Example 2, no particle enhancer is added, and no quality improvement is performed.

[0032] The metallurgical biochar obtained in Example 3 and the carbonized material particles obtained in the comparative example were crushed to 25-40 mm, and the technical indicators were measured according to the specification of "GB / T 1996-2017 Metallurgical Coke". Particles with a length of 18 mm were randomly selected from the metallurgical biochar obtained in Example 3 and the carbonized material particles obtained in this comparative example for compression strength test. The results are shown in Table 1 below: Table 1 Technical indicators of the metallurgical biochar obtained in Example 3 and the carbonized material particles obtained in the comparative example

[0033] Table 1 shows that compared with the biochar prepared using biomass as raw material by conventional technology, the crushing strength and reaction activity of the biochar prepared by the present invention can meet the first-level product requirements of "GB / T 1996-2017 Metallurgical Coke".

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A biochar preparation system for metallurgy, characterized by: The invention comprises a biomass carbonization device (1), wherein the carbonized material outlet of the biomass carbonization device (1) is connected to the feed ports of a charcoal crushing device (3), a premixing device (4) and a granulation device (5) in sequence, the combustible gas outlet of the biomass carbonization device (1) is connected to the smoke inlet of a primary combustion device (6), the discharge port of the granulation device (5) and the smoke outlet of the primary combustion device (6) are both connected to the inlet of a quality improvement device (7), and the outlet of the quality improvement device (7) is connected to the inlet of a charcoal particle cooling device (9).

2. A metallurgical biochar preparation system according to claim 1, characterized in that: The biomass carbonization device (1) is in the form of a rotary kiln structure, comprising a device body (101) and a feeding device (103); a front sealing cover (102) is provided at one end of the device body (101), and a rear sealing cover (104) is provided at the other end; an outlet end of the feeding device (103) passes through the front sealing cover (102) and extends into the interior of the device body (101); the feeding device (103) and the device body (101) are in an eccentric structure, and the distance between the center line of the feeding device (103) outlet and the upper shell of the device body (101) is greater than the distance between the feeding device (103) outlet and the lower shell.

3. A metallurgical biochar preparation system according to claim 2, characterized in that: The biomass carbonization device (1) further comprises a directional air supply device (106) and a burner (105); the air duct of the directional air supply device (106) passes through the device body (101); a plurality of air distribution holes are provided on the side wall of the device body (101); and the burner (105) is connected to the rear sealing cover (104).

4. A metallurgical biochar preparation system according to claim 1, characterized in that: The premixing device (4) is provided with a particle strengthening agent inlet. The premixing device (4) is a jacket structure. The carbonized material and the particle strengthening agent are fully mixed in the inner cylinder, and the jacket is filled with a heat carrier.

5. The system for preparing biochar for metallurgy according to claim 1, characterized in that: The upgrading device (7) is a jacket structure, and the biochar particles are upgraded at high temperature in the inner cylinder. The jacket is filled with high-temperature flue gas generated by the primary combustion device (6), and the flow direction of the high-temperature flue gas is opposite to that of the biochar particles.

6. A metallurgical biochar preparation system according to claim 1, characterized in that: The charcoal particle cooling device (9) is a jacket structure, the biomass charcoal particles are cooled in the inner cylinder, the jacket contains a heat carrier, and the outlet of the heat carrier is connected to the jacket of the premixing device (4).

7. A metallurgical biochar preparation system according to claim 1, characterized in that: It also includes a burnout and waste heat recovery device (8), a biomass drying device (10) and a carbonized material cooling device (2), wherein the flue gas inlet of the burnout and waste heat recovery device (8) is respectively connected to the jacket flue gas outlet and the inner tube flue gas outlet of the upgrading device (7), the flue gas outlet of the burnout and waste heat recovery device (8) is connected to the flue gas inlet of the biomass drying device (10), and the material outlet of the biomass drying device (10) is connected to the material inlet of the biomass carbonization device (1); The smoke outlet of the biomass drying device (10) is provided with a smoke treatment device (11); The feed inlet of the carbonized material cooling device (2) is connected to the discharge port of the biomass carbonization device (1), and the discharge port of the carbonized material cooling device (2) is connected to the feed inlet of the charcoal pulverizing device (3).

8. A method for preparing biochar for metallurgy using the system according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Biomass is added to a biomass carbonization device (1), where a carbonization reaction occurs to generate carbonized material and combustible gas; the combustible gas is sent to a primary combustion device (6) for incomplete combustion, and the generated high-temperature flue gas is sent to a jacket of a quality improvement device (7); the carbonized material is cooled by a carbonized material cooling device (2) and then sent to a charcoal crushing device (3) for crushing; S2, the crushed carbonized material is fully mixed with the particle strengthening agent in the premixing device (4) and heated by the heat carrier in the jacket, and the resulting mixture is sent to the granulating device (5) for granulation, and the generated biochar particles are sent to the upgrading device (7); S3, the biochar particles are solidified at high temperature in the upgrading device (7), and then sent to the carbon particle cooling device (9) for cooling, and the obtained product is the biochar for metallurgy; S4, the flue gas generated by the upgrading device (7) and the flue gas in the jacket are sent to the combustion and waste heat recovery device (8) to achieve combustion of combustible components in the flue gas. After the flue gas is reduced to a suitable temperature through waste heat recovery, it is sent to the biomass drying device (10) to dry the biomass, and then is treated by the flue gas treatment device (11) to meet the standards before being discharged.

9. The method according to claim 8, characterized in that: The combustion in the primary combustion device (6) is incomplete combustion, and its excess oxygen coefficient is adjusted to control the temperature of the upgrading device (7) to be maintained at 700-1050°C; the residence time of the biochar particles in the upgrading device (7) is 30-150 minutes, and the residence time of the biochar particles in the charcoal particle cooling device (9) is 10-60 minutes.

10. The method according to claim 8, characterized in that: The particle strengthener is a material that can fill the voids in carbon particles and enhance the strength of the carbon structure after high-temperature curing. The mass ratio of the particle strengthener to the carbonized material is 1: (20-50).

Images