Method for preparing powdered activated carbon from household garbage

Abstract

The invention relates to the technical field of resource utilization of household garbage and municipal sludge, in particular to a method for preparing powdered activated carbon from household garbage, which comprises the following steps of: firstly, preparing sludge garbage particles by using the household garbage and the municipal sludge as raw materials; then, pyrolyzing and carbonizing the sludge garbage particles in an organic solid waste multifunctional pyrolyzing and carbonizing furnace to obtain activated carbon; then, the activated carbon is crushed and floated, and a high-quality activated carbon suspension is obtained; and finally, carrying out spray drying on the high-quality activated carbon suspension to obtain powdery activated carbon. The powdery activated carbon is prepared from the household garbage and the municipal sludge, the municipal sludge does not need to be dried in advance, the preparation technology for preparing the activated carbon from the household garbage is simplified, the production cost of the activated carbon is remarkably reduced, efficient resource utilization of the household garbage and the municipal sludge is achieved, and the method has the advantages of saving resources, protecting the environment and improving the economic benefits. The method has important economic benefits and environmental benefits.

Description

Technical Field

[0001] The invention discloses a method for preparing powdered activated carbon from domestic garbage, and belongs to the technical field of resource utilization of domestic garbage and urban sludge. Background Art

[0002] Domestic garbage is solid waste generated by people in their daily lives, and urban sludge is solid waste generated in the process of urban domestic sewage treatment. They both have the dual attributes of pollution and resources. At present, they are mainly landfilled, which not only occupies limited land resources, but also brings the risk of secondary environmental pollution. Therefore, efficient resource utilization of domestic garbage and urban sludge is the best choice. Activated carbon is a highly porous carbon material with strong adsorption capacity and good purification effect. It plays an important role in the fields of environment, water treatment, food and drug processing, etc. Domestic garbage has the characteristics of high organic content and can be used as the main raw material source for the preparation of activated carbon.

[0003] With the rapid development of the world economy and the improvement of sewage treatment rate and the deepening of treatment degree, the output of urban sludge is increasing day by day. If urban sludge is not properly treated, it will cause serious secondary pollution. Therefore, the reasonable treatment and resource utilization of urban sludge has become one of the most difficult environmental problems at present.

[0004] In order to seek new ways to utilize urban sewage sludge as a resource, domestic and foreign scholars have systematically studied the characteristics of urban sewage sludge and reached the following consensus: (1) Urban sewage sludge has a high water content. The water content of untreated urban sewage is about 98%, and the water content of urban sewage after mechanical dehydration can be reduced to 50%-80%. (2) Urban sewage sludge is rich in organic matter (≥50%) and is similar to biomass in many aspects. Therefore, it can be used as a raw material source for activated carbon.

[0005] In the prior art, domestic waste and sludge are generally used alone as raw materials to produce activated carbon. However, when using urban sludge to make activated carbon, the urban sludge needs to be pre-dried to a state with low humidity, which is time-consuming and resource-consuming. Summary of the invention

[0006] In view of the problems in the prior art, the present invention provides a method for preparing powdered activated carbon from domestic waste.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing powdered activated carbon from domestic waste, comprising the following steps:

[0008] (1) Using domestic waste and municipal sludge as raw materials to prepare sludge waste particles;

[0009] (2) pyrolyzing and carbonizing the sludge and garbage particles in a multifunctional pyrolysis and carbonization furnace for organic solid waste to obtain activated carbon;

[0010] (3) crushing and flotation of the activated carbon to obtain a fine activated carbon suspension;

[0011] (4) The fine activated carbon suspension is spray dried to obtain powdered activated carbon.

[0012] Furthermore, the organic matter (dry basis) of the domestic waste is ≥85%, the moisture is ≤20%, and the particle size is ≤10 mm;

[0013] The municipal sludge has an organic matter content of ≥50%, a moisture content of 40%-70%, and a particle size of ≤50 mm;

[0014] The ratio of domestic garbage to urban sludge is 1:1 to 2:1.

[0015] Furthermore, the step (1) comprises conveying the domestic waste and the urban sewage sludge to a kneader in a preset ratio and mixing them for 15-20 minutes, and then conveying them to a coal rod machine for extrusion to obtain sewage sludge particles, wherein the size of the sewage sludge particles is 20-30 mm in diameter and 30-20 mm in length.

[0016] Furthermore, in step (2), the sludge garbage particles are pyrolyzed and carbonized in a multifunctional pyrolysis and carbonization furnace for organic solid waste to obtain activated carbon, and the pyrolysis conditions are: pyrolysis in an absolutely oxygen-free environment, a pyrolysis temperature of 450-500° C., and a pyrolysis time of 50-70 minutes.

[0017] Furthermore, in the step (3), a ball mill is used to grind the activated carbon with water, wherein the mass of the activated carbon: the mass of water = 1:1.2-1.5, the ball milling is performed for 20-30 minutes, and the particle size of the activated carbon after ball milling is ≤0.2 mm.

[0018] Furthermore, the crushed activated carbon suspension is transported to a flotation machine for flotation, kerosene is used as a flotation collector, and pine oil is used as a flotation frother to obtain a fine activated carbon suspension, the solid-liquid ratio of which is 400-600 g / L.

[0019] Furthermore, in step (4), a centrifugal spray dryer is used to dry the fine activated carbon suspension to obtain powdered activated carbon.

[0020] Furthermore, the multifunctional pyrolysis and carbonization furnace for organic solid waste is externally connected to an inert gas supply system, the inert gas supply system and the multifunctional pyrolysis and carbonization furnace for organic solid waste are connected via a gas supply pipe, and a gas analyzer for detecting the gas composition inside the carbonization furnace is installed inside the multifunctional pyrolysis and carbonization furnace for organic solid waste.

[0021] Furthermore, the organic solid waste multifunctional pyrolysis carbonization furnace is externally connected to a waste gas treatment system, the waste gas treatment system includes a waste gas collection pipeline, a waste gas treatment device, and a waste gas discharge pipeline, the waste gas collection pipeline is externally wrapped with a phase change material, and the air supply pipe runs through the phase change material;

[0022] The domestic garbage and urban sludge are dried by a hot air dryer before being mixed. The hot air dryer includes a hot air pipe that transports hot air into the body. The treated waste gas discharge pipe passes through the phase change material and is externally connected to the side end of the hot air pipe and communicates with the hot air pipe.

[0023] Beneficial effects of the present invention:

[0024] 1. The present invention uses domestic waste and urban sewage sludge to prepare powdered activated carbon, and there is no need to pre-dry the urban sewage sludge. This simplifies the preparation process of activated carbon from domestic waste and significantly reduces the production cost of activated carbon. At the same time, it realizes the efficient resource utilization of domestic waste and urban sewage sludge, which has important economic and environmental benefits for saving resources and protecting the environment.

[0025] 2. Heat exchange with the exhaust gas collection pipe is achieved through phase change materials, and the temperature of the high-temperature exhaust gas blown out from the multifunctional pyrolysis and carbonization furnace for organic solid waste is reduced, reducing the thermal damage caused by the high-temperature gas to the exhaust gas treatment equipment. The phase change material exchanges heat with the inert gas supply pipe and the exhaust gas treatment pipe connected to the hot air pipe, and heats the gas inside the inert gas supply pipe and the exhaust gas treatment pipe, thereby increasing the temperature of the inert gas entering the multifunctional pyrolysis and carbonization furnace for organic solid waste, reducing the amount of thermal energy consumed by the multifunctional pyrolysis and carbonization furnace for organic solid waste to ensure high temperature. The exhaust gas treated by the exhaust gas treatment equipment is transported to the hot air pipe after being heated, and auxiliary heating is performed on the domestic waste, thereby improving the efficiency of thermal resources and reducing resource waste. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0027] A method for preparing powdered activated carbon from domestic waste, comprising the following steps:

[0028] Step (1) uses domestic waste and urban sludge as raw materials to prepare sludge garbage particles. Compared with the prior art, it is not necessary to pre-dry the urban sludge, which simplifies the preparation process of activated carbon from domestic waste.

[0029] The above-mentioned domestic garbage is the solid waste generated by people in their daily lives, and the urban sludge is the solid waste generated in the process of urban domestic sewage treatment.

[0030] The organic matter (dry basis) of domestic garbage is ≥85%, the moisture is ≤20%, and the particle size is ≤10mm; the organic matter of urban sludge is ≥50%, the moisture is 40%-70%, and the particle size is ≤50mm; the ratio of domestic garbage to urban sludge is 1:1 to 2:1.

[0031] Domestic garbage and urban sludge are transported to the kneader in a preset ratio and mixed for 15-20 minutes. In this process, the sludge can be used as a binder to help the different components in the domestic garbage to be tightly combined to form a stable granular material. Then it is transported to the coal rod machine for extrusion molding to obtain sludge garbage particles. The size of the sludge garbage particles is 20-30mm in diameter and 30-20mm in length.

[0032] Preferably, before mixing, the municipal sludge is mechanically dehydrated and preliminarily screened to remove impurities in the sludge. The purpose of preparing the sludge garbage particles is to improve the efficiency of the subsequent pyrolysis carbonization process.

[0033] Step (2) pyrolyzing and carbonizing the sludge and garbage particles in a multifunctional pyrolysis and carbonization furnace for organic solid waste to obtain activated carbon;

[0034] Specifically, the pyrolysis carbonization conditions are: pyrolysis in an absolutely oxygen-free environment, a pyrolysis temperature of 450-500° C., and a pyrolysis time of 50-70 minutes.

[0035] Preferably, the activated carbon can be cooled after the carbonization treatment to avoid damaging its microscopic pore structure. The cooling treatment can be carried out in a carbonization furnace or by using air.

[0036] Step (3) crushing and floating the activated carbon to obtain a fine activated carbon suspension;

[0037] Specifically, a ball mill is used to grind the activated carbon with water, the mass of activated carbon: the mass of water = 1:1.2-1.5, and the ball milling is carried out for 20-30 minutes. The particle size of the activated carbon after ball milling is ≤0.2mm. Then, the crushed activated carbon suspension is transported to a flotation machine for flotation, kerosene is used as a flotation collector, and pine oil is used as a flotation frother to obtain a fine activated carbon suspension. The solid-liquid ratio of the fine activated carbon suspension is 400-600g / L.

[0038] Step (4) spray-drying the fine activated carbon suspension to obtain powdered activated carbon.

[0039] Specifically, the fine activated carbon suspension is dried using a centrifugal spray dryer to obtain powdered activated carbon.

[0040] The technical indicators of the powdered activated carbon obtained by the above method are: iodine value ≥900 mg / g, particle size (≤100 mesh) ≥90%, moisture Mt ≤5%, ash content Aad ≤10%, pH value: 7-9 (the above percentages all represent mass fractions).

[0041] According to the above preparation method, the following specific working steps are designed:

[0042] 1. Select raw materials:

[0043] (1) The sludge from a sewage treatment plant in a certain city has an organic matter content (dry basis) of 52% and a moisture content of 60%.

[0044] (2) The domestic waste in a certain city has an organic matter (dry basis) content of 87%, a moisture content of 16%, and a particle size of ≤10 mm.

[0045] (3) Kerosene and pine oil.

[0046] 2. Preparation method:

[0047] First, the domestic garbage and urban sludge are transported to the kneading machine in a ratio of 1:1 for mixing for 15 minutes, and then the mixture is transported to the coal rod machine for molding to obtain garbage sludge particles (particle size 20×20mm), and then the garbage sludge particles are transported to the organic solid waste multifunctional pyrolysis carbonization furnace for pyrolysis and carbonization to obtain activated carbon. The pyrolysis conditions are: pyrolysis in an absolutely anaerobic environment, pyrolysis temperature of 500℃, and pyrolysis time of 50 minutes. Subsequently, the activated carbon and water are mixed in a ratio of 1:1.4 and then crushed in a ball mill for 25 minutes to make its particle size less than 0.2mm; then the crushed activated carbon is input into the flotation machine for flotation (using kerosene and pine oil as flotation agents) to obtain a fine activated carbon suspension; finally, the fine activated carbon suspension is sent to a centrifugal spray dryer for drying to obtain powdered activated carbon.

[0048] 3. Technical performance indicators of powdered activated carbon

[0049] The iodine value of the prepared powdered activated carbon is 952 mg / g, the particle size (≤100 mesh) is 96%, the moisture content Mt is 4.25%, the ash content Aad is 7.89%, and the pH value is 7.8.

[0050] The present invention uses domestic waste and urban sewage sludge to prepare powdered activated carbon, and there is no need to pre-dry the urban sewage sludge. This simplifies the preparation process of activated carbon from domestic waste and significantly reduces the production cost of activated carbon, while also achieving efficient resource utilization of domestic waste and urban sewage sludge, which has important economic and environmental benefits for saving resources and protecting the environment.

[0051] In addition, a nitrogen or inert gas supply system is connected to the outside of the organic solid waste multifunctional pyrolysis carbonization furnace, the nitrogen or inert gas supply system and the organic solid waste multifunctional pyrolysis carbonization furnace are connected through a gas supply pipe, and a plurality of gas analyzers for detecting the gas composition inside the carbonization furnace are installed inside the organic solid waste multifunctional pyrolysis carbonization furnace;

[0052] Before starting the multifunctional pyrolysis carbonization furnace for organic solid waste, open the nitrogen or inert gas supply system and inject a certain amount of nitrogen or inert gas into the carbonization furnace.

[0053] Start the carbonization furnace heating system and adjust the gas flow control valve installed on the gas supply pipe at the same time to keep the gas flow entering the carbonization furnace at a stable level.

[0054] Use a gas analyzer to monitor the gas composition in the carbonization furnace in real time to ensure that the oxygen content is below the preset threshold.

[0055] During the pyrolysis carbonization process, the gas flow control valve and the nitrogen or inert gas supply system are adjusted in a timely manner according to the feedback from the gas analyzer to maintain an oxygen-free or low-oxygen environment in the carbonization furnace.

[0056] The organic solid waste multifunctional pyrolysis carbonization furnace is externally connected to a waste gas treatment system, which includes a waste gas collection pipeline, waste gas treatment equipment (such as an adsorption tower, a catalytic burner, etc.) and a waste gas discharge pipeline. A gas monitor is installed in the waste gas discharge pipeline to monitor the concentration of harmful gases in the waste gas in real time. The waste gas collection pipeline is wrapped with a phase change material on the outside, and the gas supply pipe also runs through the phase change material;

[0057] Before mixing the domestic garbage and the urban sludge, the domestic garbage and the urban sludge are dried by a hot air dryer. The hot air dryer includes a hot air pipe for conveying hot air to the inside of the dryer. The exhaust gas discharge pipe runs through the phase change material and is externally connected to the side end of the hot air pipe and communicates with the hot air pipe.

[0058] The exhaust gas collection pipe, the air supply pipe and the exhaust gas treatment pipe can be arranged in an S shape inside the phase change material to achieve sufficient heat exchange with the phase change material. The phase change material can be installed with a heat-insulating shell to reduce the impact of the external environment on the temperature of the phase change material.

[0059] By using phase change materials to achieve heat exchange with the exhaust gas collection pipe, the temperature of the high-temperature exhaust gas blown out from the multifunctional pyrolysis and carbonization furnace for organic solid waste is reduced, reducing the thermal damage caused by the high-temperature gas to the exhaust gas treatment equipment. The phase change material exchanges heat with the inert gas supply pipe and the treated exhaust gas discharge pipe connected to the hot air pipe, heats the gas inside the inert gas supply pipe and the treated exhaust gas discharge pipe, increases the temperature of the inert gas entering the multifunctional pyrolysis and carbonization furnace for organic solid waste, reduces the amount of thermal energy consumed by the multifunctional pyrolysis and carbonization furnace for organic solid waste to ensure high temperature, and the exhaust gas treated by the exhaust gas treatment equipment is transported to the hot air pipe after being heated, for auxiliary heating of domestic waste, thereby improving the efficiency of thermal resources and reducing resource waste.

[0060] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing powdered activated carbon from domestic waste, characterized in that: The following steps are involved: (1) Using domestic waste and municipal sludge as raw materials to prepare sludge waste particles; (2) pyrolyzing and carbonizing the sludge and garbage particles in a multifunctional pyrolysis and carbonization furnace for organic solid waste to obtain activated carbon; (3) crushing and flotation of the activated carbon to obtain a fine activated carbon suspension; (4) The fine activated carbon suspension is spray dried to obtain powdered activated carbon.

2. The method for preparing powdered activated carbon from domestic waste according to claim 1, characterized in that: The organic matter (dry basis) of the domestic waste is ≥85%, the moisture is ≤20%, and the particle size is ≤10mm; The municipal sludge has an organic matter content of ≥50%, a moisture content of 40%-70%, and a particle size of ≤50 mm; The ratio of domestic garbage to urban sludge is 1:1 to 2:

1.

3. The method for preparing powdered activated carbon from domestic waste according to claim 2, characterized in that: The step (1) comprises conveying the domestic garbage and the urban sludge to a kneader in a preset ratio and mixing them for 15-20 minutes, and then conveying them to a coal rod machine for extrusion molding to obtain sludge garbage particles, wherein the size of the sludge garbage particles is 20-30 mm in diameter and 30-20 mm in length.

4. The method for preparing powdered activated carbon from domestic waste according to claim 1, characterized in that: In step (2), the sludge garbage particles are pyrolyzed and carbonized in a multifunctional pyrolysis and carbonization furnace for organic solid waste to obtain activated carbon, and the pyrolysis conditions are: pyrolysis in an absolutely oxygen-free environment, a pyrolysis temperature of 450-500° C., and a pyrolysis time of 50-70 minutes.

5. The method for preparing powdered activated carbon from domestic waste according to claim 1, characterized in that: In the step (3), a ball mill is used to grind the activated carbon with water, wherein the mass of the activated carbon: the mass of the water = 1:1.2-1.5, and the grinding is carried out for 20-30 minutes. The particle size of the activated carbon after grinding is ≤0.2 mm.

6. The method for preparing powdered activated carbon from domestic waste according to claim 5, characterized in that: The crushed activated carbon suspension is transported to a flotation machine for flotation, kerosene is used as a flotation collector, and pine oil is used as a flotation frother to obtain a fine activated carbon suspension, the solid-liquid ratio of which is 400-600 g / L.

7. The method for preparing powdered activated carbon from domestic waste according to claim 1, characterized in that: In step (4), a centrifugal spray dryer is used to dry the fine activated carbon suspension to obtain powdered activated carbon.

8. The method for preparing powdered activated carbon from domestic waste according to claim 4, characterized in that: The multifunctional pyrolysis and carbonization furnace for organic solid waste is externally connected to an inert gas supply system, the inert gas supply system and the multifunctional pyrolysis and carbonization furnace for organic solid waste are connected via a gas supply pipe, and a gas analyzer for detecting the gas composition inside the carbonization furnace is installed inside the multifunctional pyrolysis and carbonization furnace for organic solid waste.

9. The method for preparing powdered activated carbon from domestic waste according to claim 8, characterized in that: The organic solid waste multifunctional pyrolysis carbonization furnace is externally connected to a waste gas treatment system, the waste gas treatment system includes a waste gas collection pipeline, a waste gas treatment device, and a waste gas discharge pipeline. The waste gas collection pipeline is externally wrapped with a phase change material, and the air supply pipe runs through the phase change material; The domestic garbage and urban sludge are dried by a hot air dryer before being mixed. The hot air dryer includes a hot air pipe that transports hot air into the body. The treated waste gas discharge pipe passes through the phase change material and is externally connected to the side end of the hot air pipe and communicates with the hot air pipe.