A method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil

Abstract

The present invention is a method for preparing activated carbon and liquid fertilizer by biomass pyrolysis based on the combined action of biomass vinegar liquid and biomass oil. The method stirs and mixes the crushed biomass with the vinegar liquid obtained by pyrolysis and filters it through a filter, obtains a liquid phase and sends it to a chelating tank to add N / P / K chelation to obtain liquid fertilizer; the solid phase biomass obtained by filtration is sent to a closed heating container and heated to 270-280°C and kept constant at 1-1.5, and then sent to a pyrolysis furnace for pyrolysis, and the gas phase is obtained after pyrolysis. After condensation and centrifugal separation of vinegar liquid and biomass oil, the gas phase is obtained for pyrolysis, and after a certain proportion of biochar and biomass oil is ultrasonically separated, it is sent to an activation furnace for activation to obtain high-quality, high-yield activated carbon. The present invention uses the combined action of vinegar liquid and biomass oil produced by pyrolysis to solve the problems of high cost, pollution, low quality and low yield of activated carbon made from biochar in traditional biomass quality improvement methods, and finally obtains high-quality activated carbon and liquid fertilizer.

Description

Technical Field

[0001] The invention relates to a method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil, and belongs to the field of biomass energy. Background Art

[0002] The quality of conventional biomass pyrolysis products is not high, and the pyrolysis polygeneration mechanism with the goal of improving product quality has become the focus of researchers. Clarifying the coupling mechanism between raw material quality improvement, process regulation and product quality in the pyrolysis chain is an important way to achieve high product quality.

[0003] Biomass has the disadvantages of strong hydrophilicity, difficulty in grinding, high water and oxygen content, and low energy density. Therefore, proper modification and pretreatment are often required before biomass utilization. AVBridgwater, an internationally renowned biomass energy expert, and the International Energy Agency (IEA) both pointed out that the high oxygen content of biomass is the direct cause of the high content of oxygen-containing chemical components in bio-oil, and the quality improvement of raw materials plays a vital role in subsequent pyrolysis. In recent years, quality improvement technology aimed at improving biomass raw materials and thus improving the quality of pyrolysis products has received attention.

[0004] There are two ways to improve the quality of raw materials: water washing and deashing and acid washing and deashing. The water washing liquid after water washing and deashing contains a large amount of alkaline earth metals, which pollute the environment and must be purified before it can be recycled. Acid washing and deashing studies have shown that both inorganic acids (such as hydrochloric acid) and organic acids (such as acetic acid) can effectively remove ash and metal elements from biomass, thereby improving the quality of bio-oil. However, using inorganic and organic acids to treat biomass is not only costly, but also polluting.

[0005] The high-value utilization of biochar, the main product of biomass pyrolysis, is directly related to the promotion and application of biomass pyrolysis technology. The preparation of high-value-added activated carbon from biochar obtained after biomass pyrolysis is a major direction. Traditional biochar has two major problems: low quality of biochar and high yield and low cost of activated carbon biomass process.

[0006] Therefore, there is an urgent need to develop a technology that can solve the above-mentioned problems of low quality and utilization of by-products through process regulation without adding additional substances and in an environmentally friendly manner. Summary of the invention

[0007] In view of the above problems of the prior art, the present invention provides a novel, low-cost, systematic method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil, which can obtain high-quality activated carbon and liquid fertilizer.

[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil, comprising the following steps:

[0009] (1) Biomass pretreatment: biomass crushed to 20 mesh and vinegar solution were fed into a reactor, wherein the volume ratio of biomass to vinegar solution was 1:1-3, heated to 50-60°C, and stirred for 30 minutes;

[0010] (2) Filtration - liquid phase: The mixture obtained in step (1) is sent to a filter for filtration, and the obtained liquid phase is sent to a chelation tank, heated to 40° C., water is added to adjust the pH value to 6-6.5, and N / P / K is added for chelation to obtain liquid fertilizer;

[0011] (3) Filtration - solid phase: The solid phase obtained by filtration, i.e. the treated biomass, is sent to a closed heater, heated to 270-280°C at a rate of 20°C / min, and maintained at a constant temperature for 1-1.5h;

[0012] (4) Preparation of vinegar liquid and activated carbon precursor: The biomass obtained in step (3) is pyrolyzed at 550°C to 600°C to obtain gas and biochar. The gas is condensed and centrifuged to obtain vinegar liquid, non-condensable gas and bio-oil. The non-condensable gas is a combustion gas and is used to provide heat required for pyrolysis. The bio-char and bio-oil are fed into an ultrasonic tank at a weight ratio of 4-6:1. After ultrasonication and stirring for 1 hour, an activated carbon precursor is obtained.

[0013] (5) Activation of carbon: The activated carbon precursor is sent into a rotary activation furnace for activation to obtain activated carbon.

[0014] Wherein, the biomass in step (1) is wood chips and fruit shells, and the moisture content is ≤40%.

[0015] Wherein, the vinegar solution in step (1) is the vinegar solution obtained by pyrolysis in step (4).

[0016] Beneficial effects of the present invention:

[0017] (1) The vinegar liquid condensed and separated from the gas phase by self-pyrolysis is mixed with biomass, and the ash such as alkali metals is transferred to the vinegar liquid. The vinegar liquid containing alkali metals is used to make liquid fertilizer, which not only utilizes the ash such as alkali metals as resources, but also utilizes the vinegar liquid as resources, and at the same time improves the quality of biomass.

[0018] (2) The biomass oil produced by its own pyrolysis is coupled with the biomass charcoal to increase the antioxidant capacity and volatile matter of the biomass charcoal, improve the yield of the biomass charcoal, reduce the ash content, and improve the quality and production cost of the activated carbon.

[0019] (3) This system method not only obtains liquid fertilizer, but also obtains high-quality activated carbon, killing two birds with one stone. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of a method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass. DETAILED DESCRIPTION

[0021] A method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil, comprising the following steps:

[0022] (1) Biomass pretreatment: grind wood chips with a moisture content of ≤40% to 20 mesh and the biomass vinegar solution obtained in step (4) into a reactor, wherein the volume ratio of biomass to vinegar solution is 1:2, heat to 50-60°C, and stir for 30 minutes;

[0023] (2) Filtration - Liquid Phase: The mixture obtained in step (1) is sent to a filter for filtration, and the obtained liquid phase is sent to a chelation tank, heated to 40°C, and water is added to adjust the pH value to 6-6.5, and N / P / K is added according to the required proportion of the plant used, and the temperature is raised to 60°C, stirred and chelated to obtain liquid fertilizer;

[0024] (3) Filtration - solid phase: The solid phase obtained by filtration, i.e. the treated biomass, is sent to a closed heater, heated to 270-280°C at a rate of 20°C / min, and maintained at a constant temperature for 1-1.5h;

[0025] (4) Preparation of vinegar liquid and activated carbon precursor: The biomass obtained in step (3) is fed into a pyrolysis furnace and pyrolyzed at 550°C to 600°C to obtain gas and biochar. The gas is condensed and centrifuged to obtain vinegar liquid and biooil. The non-condensable gas, i.e., combustible gas, is burned to provide heat required for pyrolysis. The biochar and biooil are fed into an ultrasonic tank at a weight ratio of 5:1. After ultrasonic stirring for 1 hour, an activated carbon precursor is obtained.

[0026] (5) Activation of carbon: The activated carbon precursor is sent into a rotary activation furnace for activation to obtain activated carbon.

[0027] Table 1 Physical and chemical analysis of wood chips and wood chips entering pyrolysis furnace

[0028]

[0029] The industrial analysis, elemental analysis, and calorific value results of the raw material wood chips in step (1) and the biomass obtained in step (3) before entering the pyrolysis furnace are listed in Table 1. It can be seen from Table 1 that the ash content after quality improvement is reduced from 5.56% to 3.91%. This means that this solution can significantly reduce the ash content in the sample. Compared with the raw material, the volatile matter content decreases, while the fixed carbon content increases significantly. At the same time, the carbon content is greatly increased and the oxygen content is greatly reduced, so that the molar ratio of H / O and O / C is also reduced, and the calorific value of the sample is significantly increased.

[0030] Table 2 Metal element analysis of wood chips and wood chips before entering the pyrolysis furnace

[0031] sample K(μg / g) Ca(μg / g) Mg(μg / g) Fe(μg / g) Al(μg / g) Na(μg / g) No quality improvement 9210 8465 2678 1192 920 737 Before entering the pyrolysis furnace 1350 3950 962 485 698 68

[0032] The metal element content of the sample is shown in Table 2. After the quality improvement of the present invention, the metal content in the wood chips is reduced to varying degrees, among which the removal effect of K, Na and Mg elements is more obvious, especially K and Na, the removal rate reaches 90-95%. There is also a certain removal effect on other metal elements, such as Ca and Fe The removal rate has reached more than 50%. This shows that the present invention has a good removal effect on the metal elements in the wood chips.

[0033] Coupling results of biomass oil and wood chip pyrolysis carbon: The activated carbon precursor obtained by coupling 1kg of biomass carbon with 0.2kg of biomass oil was sent to the activation furnace for activation to obtain 0.6kg of activated carbon. The elemental analysis, yield and iodine value analysis of the activated carbon showed that the yield of activated carbon was 60% and the iodine value was 1150mg / g; the elemental analysis of activated carbon showed that [C] was 91.45%, [H] was 1.66%, [N] was 0.24%, [O] was 4.69%, and the ash content was 1.96%.

[0034] The results of producing activated carbon from wood chip charcoal alone without coupling with biomass oil: 1 kg of biomass charcoal was sent to the activation furnace for activation to obtain 0.52 kg of activated carbon. The elemental analysis, yield and iodine value analysis of the activated carbon showed that the yield of activated carbon was 52% and the iodine value was 988 mg / g; the elemental analysis of activated carbon showed that [C] was 88.35%, [H] was 1.45%, [N] was 0.27%, [O] was 5.73%, and the ash content was 1.96%.

[0035] The results showed that the coupling of biomass oil improved the antioxidant properties of biochar and increased the quality and yield of activated carbon.

[0036] The present invention is a method for preparing activated carbon and liquid fertilizer by biomass pyrolysis based on the combined action of biomass vinegar liquid and biomass oil. The method comprises the following steps: mixing the crushed biomass with the vinegar liquid obtained by pyrolysis, filtering the mixture through a filter, and sending the obtained liquid phase into a chelating tank, adding N / P / K chelation according to the required proportion of the plant used to obtain liquid fertilizer; filtering the obtained solid phase biomass into a closed heating container, heating it to 270-280°C and keeping the temperature constant for 1-1.5, and then sending it into a pyrolysis furnace for pyrolysis, and obtaining a gas phase after pyrolysis, condensing, centrifuging and separating the vinegar liquid and biomass oil, obtaining a gas phase for pyrolysis, obtaining a certain proportion of biochar and biomass oil, and ultrasonicating the mixture, and then sending it into an activation furnace for activation to obtain high-quality and high-yield activated carbon. The present invention solves the problems of high cost and pollution of water washing and acid washing in traditional biomass quality improvement methods, and low quality and low yield of activated carbon made from biochar, with low cost, and finally obtains high-quality activated carbon and liquid fertilizer.

Claims

1. A method for preparing activated carbon and liquid fertilizer by pyrolysis of biomass based on the combined action of biomass vinegar liquid and biomass oil, characterized in that The following steps are involved: (1) Biomass pretreatment: biomass crushed to 20 mesh and vinegar liquid are fed into a reactor, wherein the volume ratio of biomass to vinegar liquid is 1:1-3, heated to 50-60°C, and stirred for 30 minutes; the biomass is wood chips with a moisture content of ≤40%, and the vinegar liquid is the vinegar liquid obtained by pyrolysis in step (4); (2) Filtration - liquid phase: The mixture obtained in step (1) is sent to a filter for filtration, and the obtained liquid phase is sent to a chelation tank, heated to 40°C, water is added to adjust the pH value to 6-6.5, N / P / K is added, and the temperature is raised to 60°C and stirred for chelation to obtain liquid fertilizer; (3) Filtration - solid phase: The solid phase obtained by filtration, i.e. the treated biomass, is sent to a closed heater, heated to 270-280°C at a rate of 20°C / min, and maintained at a constant temperature for 1-1.5h; (4) Preparation of vinegar liquid and activated carbon precursor: The biomass obtained in step (3) is pyrolyzed at 550°C-600°C to obtain gas and biochar. The gas is condensed and centrifuged to obtain vinegar liquid, non-condensable gas and bio-oil. The non-condensable gas is a combustion gas and is used to provide heat required for pyrolysis. The biochar and bio-oil are fed into an ultrasonic tank at a weight ratio of 4-6:

1. After ultrasonication and stirring for 1 hour, an activated carbon precursor is obtained. (5) Activation of carbon: The activated carbon precursor is sent into a rotary activation furnace for activation to obtain activated carbon.

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