CO2 / H2O directly-heated biomass carbonization / activation method and equipment thereof

Abstract

The invention provides a CO2 / H2O directly-heated biomass carbonization / activation method and equipment thereof, and relates to the technical field of resource circulation, the equipment comprises a preheating section, a carbonization / activation section, a material sealing section and a coke quenching section, and the carbonization / activation section is connected with an oxygen-enriched combustion device through a hot air pipe. The invention also provides a method which comprises the following steps: adding biomass granules into the preheating section; introducing a gas heat carrier to carry out a directly-heated carbonization reaction, wherein the gas heat carrier is a mixed gas of gaseous CO2 and H2O; and collecting the mixed product gas and the active coke. According to the method disclosed by the invention, CO2 / H2O (g) is taken as a heat carrier to construct a biomass directly-heated carbonization / activation system, and the generation of a C vacancy of a biological coke / carbon surface interface is promoted through a carbon thermal reaction, a water gas shift reaction and the like, so that the pore growth is promoted, the specific surface area and the activity are improved, the heat transfer efficiency and the carbonization efficiency are improved, and the emission of carbon dioxide is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of resource recycling, and in particular to a CO2 / H2O direct-heating biomass carbonization / activation method and equipment thereof. Background Art

[0002] Activated coke / carbon is the basic raw material / fuel for the pillar industries of the national economy, such as metallurgy and chemical industry. Under the dual challenges of the current shortage of coking coal resources and environmental constraints, it is urgent to find clean, green, low-carbon alternative raw materials and preparation methods.

[0003] Carbonization refers to the process in which macromolecular hydrocarbon organic matter breaks chemical bonds such as CC, CH or CO when heated, volatile substances are precipitated, and solid coke / char is formed. Traditional coke is formed by indirect heating and carbonization (or dry distillation) of coal at high temperature without oxygen. A typical example is the coking process of a coke oven, in which a large number of carbonization chambers and combustion chambers are divided by refractory partitions. Among them, coke is concentrated in the carbonization chamber, and the fuel is passed into the combustion chamber to burn and produce flames and high-temperature flue gas; the heat of the flame and flue gas is transferred to the refractory partition through radiation or convection, and further transferred to the carbonization chamber on the other side through heat conduction or radiation, so that the coke in the carbonization chamber is heated and carbonized. The above-mentioned carbonization / pyrolysis using coal as raw material causes a large amount of CO2 emissions. At the same time, indirect heating has problems such as slow heat transfer and low carbonization efficiency, resulting in a small specific surface area of ​​coke / char and difficulty in improving activity. Summary of the invention

[0004] The present invention provides a CO2 / H2O direct-heat biomass carbonization / activation method and equipment thereof, so as to solve the problems of large carbon dioxide emission, slow heat transfer and low carbonization efficiency in the carbonization / pyrolysis process using coal as raw material in the prior art.

[0005] In order to solve the above-mentioned invention object, the technical solution provided by the present invention is as follows:

[0006] A CO2 / H2O direct-heating biomass carbonization / activation device comprises a preheating section, a carbonization / activation section, a material sealing section and a coke quenching section which are arranged in sequence from top to bottom. The preheating section and the carbonization / activation section are connected. The preheating section is connected to a condensing device through a pipeline, and the carbonization / activation section is connected to an oxygen-enriched combustion device through a hot air pipe.

[0007] Preferably, the condensing device is connected to a gas storage cabinet.

[0008] A CO2 / H2O direct-heat biomass carbonization / activation method, based on the above-mentioned equipment, comprises the following steps:

[0009] S1, adding biomass pellets into the preheating section from the feed inlet of the equipment;

[0010] S2, introducing a gas heat carrier into the carbonization / activation section to perform a direct-heat carbonization reaction with the biomass particles to obtain high-temperature activated coke and a mixed product gas, wherein the gas heat carrier is a mixed gas of gaseous CO2 and H2O;

[0011] S3, collecting the mixed product gas, and adjusting the material sealing section to allow the high-temperature activated coke to enter the coke quenching section, and obtaining activated coke after cooling.

[0012] Preferably, the particle size of the biomass pellets in S1 is 10-30 mm.

[0013] Preferably, the biomass pellets in S1 have a moisture content of ≤10% and a carbon content of 45% to 50%. Preferably, the biomass pellets in S1 are corn stalk pellets.

[0014] Preferably, the temperature of the gas heat carrier in S2 is 350-800°C.

[0015] Preferably, the gas volume ratio of CO2 and H2O in the gas heat carrier in S2 is 1:2.

[0016] Preferably, the mixed product gas includes gaseous CO, H2, C n H m , two or more gases in gaseous H2O, the C n H m It is one or more of CH4, C2H4, C2H6, and C3H6.

[0017] Preferably, the mass ratio of the biomass pellets to the CO2 is 1:1-3.

[0018] The particle size of biomass pellets is 10~30 mm. Within this particle size range, it can ensure good air permeability in the biomass pellet bed while meeting the requirements of efficient heat and mass transfer of single particles. The moisture content is ≤10%, and the carbon content is 45%~50%. Before the biomass pellets enter the carbonization furnace, they are dried and pretreated to reduce their moisture content to less than 10%, which can improve the heat utilization efficiency in the carbonization furnace - more heat is used to carbonize the biomass rather than drying its moisture. The carbon content is guaranteed to be between 45% and 50% to improve the quality of the carbonization product - biocoke.

[0019] Since the CO2 / H2O(g) direct-heat carbonization process involves chemical reactions at the same time, the biomass carbonization and activation processes are coupled to each other, so the biomass vertical kiln is divided from top to bottom into a preheating section, a carbonization / activation section, a material sealing section, and a coke quenching section. Oxygen and carbon dioxide need to be input into the oxygen-enriched combustion device. The medium-high temperature flue gas CO2 / H2O(g) generated in the oxygen-enriched combustion device is used as a heat carrier to pass into the carbonization / activation section of the CO2 / H2O direct-heated biomass carbonization / activation equipment. The formed biocoke falls into the coke quenching section of CO2 and performs countercurrent heat exchange with the room temperature CO2 introduced from the bottom to recover the coke / charcoal waste heat. The heated CO2 is passed into the oxygen-enriched combustion device to adjust the O2 concentration, combustion temperature, and the CO2 / H2O(g) ratio of the combustion flue gas during the combustion process; the CO / H2 formed in the carbonization / activation section and the volatile gas C n H m , H2O(g), etc. are introduced into the preheating section, C n H m The waste heat of the gas is used to dry and preliminarily heat the biomass blocks; then the mixed product gas CO / H2 / C n H m / H2O(g) and other substances are discharged from the top side of the biomass carbonization / activation equipment. After the product gas is condensed and H2O(l) is removed, CO / H2 / C n H m Fuel, stored in gas tanks.

[0020] The oxygen-enriched combustion device is set outside the biomass shaft kiln instead of being an integrated device, so as to realize the flexible arrangement and uniform heating of the heat carrier CO2 / H2O(g) gas flow in the shaft kiln. This design avoids the problems of local over-temperature and uneven carbonization caused by direct contact between the combustion flame and the biomass block.

[0021] During the carbonization process, the volume of biomass blocks gradually decreases due to the precipitation of volatile components. In order to ensure the uniformity of feeding in the biomass shaft kiln, the cross-sectional size of the quenching section is designed to be smaller than that of the preheating section and the carbonization / activation section.

[0022] In the present invention, medium-high temperature CO2 / H2O(g) is directly introduced as a heat carrier gas and penetrates the biomass stacking material layer, and the carbonization efficiency is improved by strengthening the heat transfer through direct gas / solid contact, and carbonization and activation are performed, so that the simple heating carbonization is transformed into the heating / thermochemical coupling high-efficiency / high-quality carbonization. The carbonization process is as shown in Formula I;

[0023] (I)

[0024] During the activation process, the pores of coke / char gradually increase and turn into activated coke / char. The carbon thermal reaction (as shown in Formula II) and water-gas shift reaction (as shown in Formula III) promote the generation of "C" vacancies on the surface of biochar / char, thereby promoting its pore growth and increasing its specific surface area / activity. At the same time, CO2 is reduced to CO and H2O(g) is reduced to H2, and high calorific value biomass carbonization product gas can be obtained, and CO2 resource utilization can be realized.

[0025] (II)

[0026] (III)

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The equipment process principle of the present invention is ingenious, easy to operate, and can effectively utilize heat sources to achieve energy conservation and emission reduction. The CO2 / H2O(g) produced by oxygen-enriched combustion is used as a heat carrier to construct a biomass direct-heat carbonization / activation system, which transforms the simple heating process of traditional carbonization into a high-efficiency / high-quality carbonization coupled with heating / thermochemical reaction. The formation of "C" vacancies on the surface interface of biochar / char is promoted through carbon thermal reaction, water-gas shift reaction, etc., thereby promoting its pore growth and increasing its specific surface area / activity, achieving improved heat transfer efficiency and carbonization efficiency, reducing carbon dioxide emissions, and converting CO2 into CO resources while producing green activated coke, realizing high-value recycling of carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the structure of a CO2 / H2O direct-heat biomass carbonization / activation device provided by the present invention;

[0030] Figure 2 The statistical result diagram of gas, light oil, heavy oil and char in the products after carbonization of biomass pellets in Examples 1 to 3;

[0031] Figure 3 is the heat transfer resistance in the corn straw pellet bed in Examples 1-3 and the comparative example.

[0032] Among them: 1-preheating section; 2-carbonization / activation section; 3-material sealing section; 4-coke quenching section; 5-oxygen-enriched combustion device; 6-condensation device; 7-gas storage cabinet. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a CO2 / H2O direct heating biomass carbonization / activation device, such as Figure 1 As shown, it includes a preheating section 1, a carbonization / activation section 2, a material sealing section 3 and a quenching section 4 which are arranged in sequence from top to bottom. The preheating section 1 and the carbonization / activation section 2 are connected. The preheating section 1 is connected to a condensing device 6 through a pipeline. The carbonization / activation section 2 is connected to an oxygen-enriched combustion device 5 through a hot air pipe. The condensing device 6 is connected to a gas storage cabinet 7.

[0036] A CO2 / H2O direct-heat biomass carbonization / activation method, based on the above-mentioned equipment, comprises the following steps:

[0037] S1. Add corn stalk pellets from the feed port of the equipment into the preheating section 1, wherein the corn stalk pellets have a particle size of 10 mm, a moisture content of ≤10%, and a carbon content of 45%;

[0038] S2, introducing 350°C gas heat carrier into the carbonization / activation section 2 to carry out direct heating carbonization reaction with the corn stalk pellets for 1 hour to obtain high-temperature activated coke and gaseous CO, H2, C n H m and gaseous H2O, C n H m CH4, C2H4, C2H6 and C3H6, the gas volume ratio of CO2 and H2O in the gas heat carrier is 1:2, and the mass ratio of corn straw pellets to the CO2 is 1:1;

[0039] S3, collecting the mixed product gas, and adjusting the material sealing section 3 to allow the high-temperature activated coke to enter the coke quenching section 4, and obtaining activated coke after cooling.

[0040] Example 2

[0041] This embodiment provides a CO2 / H2O direct heating biomass carbonization / activation device, such as Figure 1As shown, it includes a preheating section 1, a carbonization / activation section 2, a material sealing section 3 and a quenching section 4 which are arranged in sequence from top to bottom. The preheating section 1 and the carbonization / activation section 2 are connected. The preheating section 1 is connected to a condensing device 6 through a pipeline. The carbonization / activation section 2 is connected to an oxygen-enriched combustion device 5 through a hot air pipe. The condensing device 6 is connected to a gas storage cabinet 7.

[0042] A CO2 / H2O direct-heat biomass carbonization / activation method, based on the above-mentioned equipment, comprises the following steps:

[0043] S1. Add corn stalk pellets from the feed port of the equipment into the preheating section 1, wherein the corn stalk pellets have a particle size of 20 mm, a moisture content of ≤10%, and a carbon content of 48%;

[0044] S2, introduce 600℃ gas heat carrier into the carbonization / activation section 2 to carry out direct heating carbonization reaction with the biomass particles for 0.5 hours to obtain high temperature activated coke and gaseous CO, H2, C n H m and gaseous H2O, C n H m CH4, C2H4, C2H6 and C3H6, the gas volume ratio of CO2 and H2O in the gas heat carrier is 1:2, and the mass ratio of corn straw pellets to the CO2 is 1:2;

[0045] S3, collecting the mixed product gas, and adjusting the material sealing section 3 to allow the high-temperature activated coke to enter the coke quenching section 4, and obtaining activated coke after cooling.

[0046] Example 3

[0047] This embodiment provides a CO2 / H2O direct-heat biomass carbonization / activation device, such as Figure 1 As shown, it includes a preheating section 1, a carbonization / activation section 2, a material sealing section 3 and a quenching section 4 which are arranged in sequence from top to bottom. The preheating section 1 and the carbonization / activation section 2 are connected. The preheating section 1 is connected to a condensing device 6 through a pipeline. The carbonization / activation section 2 is connected to an oxygen-enriched combustion device 5 through a hot air pipe. The condensing device 6 is connected to a gas storage cabinet 7.

[0048] A CO2 / H2O direct-heat biomass carbonization / activation method, based on the above-mentioned equipment, comprises the following steps:

[0049] S1. Add corn stalk pellets from the feed port of the equipment into the preheating section 1, wherein the corn stalk pellets have a particle size of 30 mm, a moisture content of ≤10%, and a carbon content of 50%;

[0050] S2, introducing 800℃ gas heat carrier into the carbonization / activation section 2 to carry out direct heating carbonization reaction with the biomass particles for 0.8 hours to obtain high-temperature activated coke and gaseous CO, H2, C n H m and gaseous H2O, C n H m The gas volume ratio of CO2 and H2O in the gas heat carrier is 1:2, and the mass ratio of corn straw pellets to the CO2 is 1:3;

[0051] S3, collecting the mixed product gas, and adjusting the material sealing section 3 to allow the high-temperature activated coke to enter the coke quenching section 4, and obtaining activated coke after cooling.

[0052] The gas, light oil, heavy oil and carbon in the products of Examples 1 to 3 were statistically analyzed using a gas chromatograph and a liquid chromatograph. The calculation results are as follows: Figure 2 As shown, as the CO2 concentration increases, the C in the biochar reacts chemically with CO2 to produce CO, thereby increasing the proportion of gaseous products and reducing the proportion of solid carbon products.

[0053] Comparative Example

[0054] The same amount of corn stalk pellets as in Example 1 were taken and carbonized using a conventional process, i.e., indirect heating of the corn stalk pellets.

[0055] The heat transfer resistance in the corn straw pellet bed in Examples 1-3 and the comparative example was measured. The measurement results are as follows: Figure 3 As shown. Due to the use of CO2 / H2O direct heating carbonization process, the heat transfer resistance of Examples 1-3 is 0.02K / W, 0.03 K / W, and 0.04 K / W, respectively, which is only 3% to 8% of the traditional indirect heating carbonization. This shows that the heat transfer efficiency of the direct heating carbonization of the present invention is relatively high.

[0056] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A CO2 / H2O direct heating biomass carbonization / activation equipment, characterized in that: The invention comprises a preheating section, a carbonization / activation section, a material sealing section and a coke quenching section which are arranged in sequence from top to bottom. The preheating section and the carbonization / activation section are connected. The preheating section is connected to a condensing device through a pipeline. The carbonization / activation section is connected to an oxygen-enriched combustion device through a hot air pipe.

2. The device according to claim 1, characterized in that The condensing device is connected to the gas storage cabinet.

3. A CO2 / H2O direct-heat biomass carbonization / activation method, based on the device described in claim 1 or 2, characterized in that: The following steps are involved: S1, adding biomass pellets into the preheating section from the feed inlet of the equipment; S2, introducing a gas heat carrier into the carbonization / activation section to perform a direct-heat carbonization reaction with the biomass particles to obtain high-temperature activated coke and a mixed product gas, wherein the gas heat carrier is a mixed gas of gaseous CO2 and H2O; S3, collecting the mixed product gas, and adjusting the material sealing section to allow the high-temperature activated coke to enter the coke quenching section, and obtaining activated coke after cooling.

4. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The particle size of the biomass pellets described in S1 is 10-30 mm.

5. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The biomass pellets described in S1 have a moisture content of ≤10% and a carbon content of 45% to 50%.

6. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The biomass pellets described in S1 are corn straw pellets.

7. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The temperature of the gas heat carrier in S2 is 350-800°C.

8. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The gas volume ratio of CO2 and H2O in the gas heat carrier described in S2 is 1:

2.

9. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The mixed product gas includes gaseous CO, H2, C n H m , two or more gases in gaseous H2O, the C n H m It is one or more of CH4, C2H4, C2H6, and C3H6.

10. A CO2 / H2O direct-heat biomass carbonization / activation method according to claim 3, characterized in that: The mass ratio of the biomass pellets to the CO2 is 1:1-3.

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