Low-voltage arc ignition regeneration and activation method for composite granulation of waste cloth and powdered carbon

Abstract

The invention discloses a low-voltage arc ignition regeneration activation method for composite granulation of waste cloth and powdered carbon, which comprises the following steps: removing impurities from waste powdered activated carbon, mixing the waste powdered activated carbon with a waste cloth fiber raw material, carrying out pyrolysis and extrusion granulation, and carrying out bonding granulation by using a molten phase obtained after pyrolysis of the waste cloth fiber raw material to form columnar particles; the ash content proportion of the activated carbon in the columnar particles is reduced through the molten phase, and pore optimization and construction are achieved; drying the columnar particles to obtain columnar activated carbon; and regenerating and activating the columnar activated carbon in different temperature zones to obtain a regenerated activated carbon finished product. The invention develops a new way for treating the waste cloth and the waste powdered activated carbon, solves the problems of low regeneration efficiency, high carbon loss, serious damage to pore structure and the like of the powdered activated carbon, improves the specific surface area and adsorption performance of the regenerated activated carbon, participates in structure construction by using a cracking product of cloth fiber, realizes full utilization of carbon resources, and reduces the production cost. And the high-value utilization of dual wastes is realized while the granulation forming performance is ensured, so that the environment-friendly benefit and the economic value are realized at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of activated carbon regeneration and solid waste resource utilization, and in particular to a method for granulating waste cloth fibers and waste powdered activated carbon together and regenerating and activating the same through low-pressure arc starting technology. BACKGROUND

[0002] Waste powdered activated carbon is usually difficult to directly regenerate and utilize due to its small particle size, high impurity content, and low carbon content. At the same time, the problem of waste cloth treatment is increasingly prominent. Waste cloth has a wide source and complex material, including cotton, hemp, silk, wool, and other natural or synthetic fibers, and is difficult to sort. Recycling of fibers requires high cloth purity, complex process, and high dependence on manual work, and has low processing efficiency and high cost. Burial and incineration and other methods are prone to cause soil and air pollution, and are difficult to achieve green disposal.

[0003] In terms of composition, the main chemical components of waste cloth are cellulose and lignin, and the main elements are carbon, oxygen, and hydrogen, which are highly consistent with the basic element composition of activated carbon. According to research, in waste cloth from urban life, the proportion of natural fibers (such as cotton, hemp, etc.) is generally 45%–60%, and the proportion of synthetic fibers (such as PET, nylon, etc.) is about 35%–50%. Cotton fibers and polyester fibers together constitute the main components of waste cloth, both have good pyrolysis carbon yield, and generate porous structure carbon source and natural melting binder in the high temperature pyrolysis process. The chemical behavior of different types of waste cloth in the thermal cracking process is as follows:

[0004] The main component of cotton and hemp natural fibers is cellulose ( ), and the high temperature main pyrolysis reaction is as follows:

[0005]

[0006] Pyrolysis is mainly divided into three stages: dehydration (200–300°C), main pyrolysis (300–400°C), and carbonization (400–600°C), which can generate biochar, a small amount of bio-oil, and gaseous products. The solid phase carbon structure has a good basis for the development of micropores.

[0007] The thermal cracking reaction of synthetic fibers (such as PET) can be represented as:

[0008]

[0009] The PET cracking gas includes benzene, toluene, terephthalic acid (TPA), and other aromatic intermediates, and generates a high-viscosity molten phase (carbon black structure or amorphous carbon) during thermal cracking, which coats the surface of the particles during the cooling process and can spontaneously provide adhesion.

[0010] Therefore, it is necessary to apply the waste cloth cooperatively in the reactivation granulation of the powdered activated carbon to improve the reactivation effect of the powdered activated carbon. SUMMARY

[0011] The present application aims to provide a powdered activated carbon regeneration method which utilizes waste cloth fibers as skeleton materials, composites with waste powdered activated carbon for granulation, and adopts low-pressure arc regeneration technology for regeneration and activation. Considering that the waste cloth mainly contains carbon, hydrogen and oxygen elements, the biochar produced by pyrolysis of the waste cloth under high temperature conditions can be used as a supplementary carbon source to reduce the ash content of the activated carbon, and the molten phase in the pyrolysis process of synthetic fibers can be used as a natural binder, so that the waste cloth and waste powdered activated carbon are used as raw materials to realize the shaping, solidification and preliminary structure support of the particles without adding any external adhesive, and then the low-pressure arc regeneration technology is used for regeneration and activation, which develops a new way for the treatment of waste cloth and waste powdered activated carbon, and also solves the problems of low efficiency, high carbon loss and serious damage to pore structure during the regeneration of powdered activated carbon, improves the specific surface area and adsorption performance of the reactivated activated carbon, utilizes the pyrolysis products of cloth fibers to participate in structure construction, and realizes the full utilization of carbon resources.

[0012] The technical scheme adopted by the present application is as follows:

[0013] The low-pressure arc reactivation method for waste cloth and powdered carbon composite granulation of the present application has the following steps:

[0014] S1: The waste powdered activated carbon is put into a settling tank to remove impurities, and the obtained product is used as a main raw material.

[0015] S2: After the waste cloth is collected, crushed and opened, the waste cloth fiber raw material is separated.

[0016] S3: The waste cloth fiber raw material is mixed with the main raw material, pyrolysis and extrusion granulation are carried out, the molten phase after pyrolysis of the waste cloth fiber raw material is used as a binder to realize bonding granulation, forming columnar particles, and the molten phase serves as a supplementary carbon source, not only reducing the ash content of the activated carbon in the columnar particles, but also playing a role in reinforcing the main raw material and its own pores, and constructing new pores together with the main raw material; the columnar particles are dried to remove water, and columnar activated carbon is obtained.

[0017] S4: A low-pressure arc regeneration device is used to regenerate and activate the columnar activated carbon in temperature zones, CO2 gas is introduced into the medium temperature zone of 450 DEG C to 550 DEG C to promote the development of micropores and keep the micropore channels clean, and water vapor is introduced into the high temperature zone of 750 DEG C to 850 DEG C to realize deep activation and micropore structure construction, and finally the reactivated activated carbon product is obtained.

[0018] Preferably, the waste powdered activated carbon is produced in the process of water treatment, waste gas treatment or soil remediation.

[0019] Preferably, the opening is performed by an opener.

[0020] Preferably, the waste cloth fiber raw material is separated by a drum sieve.

[0021] Preferably, the length of the waste cloth fiber raw material is not greater than 5 mm.

[0022] Preferably, the waste cloth fiber raw material is mixed with the main raw material at a mass ratio of 1:4.

[0023] Preferably, the diameter of the columnar activated carbon is 3 mm, and the length is 3-5 mm.

[0024] Preferably, the drying temperature is 150 DEG C, and the drying time is 4 hours.

[0025] Preferably, the CO2 gas flow rate in the medium temperature zone is 3 L / min, and the water vapor flow rate in the high temperature zone is 10 L / min.

[0026] Preferably, after step S4 is performed, the regenerated activated carbon product is measured for iodine adsorption value and activated carbon ash content.

[0027] The present application has the beneficial effects:

[0028] 1. The present application organically combines the difficult-to-handle waste cloth with the difficult-to-regenerate powdered activated carbon, realizes high-value utilization of double waste while ensuring granulation forming performance, and has both environmental protection benefits and economic value.

[0029] 2. The present application realizes adhesion with powdered activated carbon through pyrolysis of cloth fibers, without adding any exogenous adhesive, achieves granulation, solidification and preliminary structural support (which includes reinforcement of original pores of powdered activated carbon and cloth fibers and construction of new pores), forms waste cloth and waste powdered activated carbon composite granulation, effectively improves the carbon content of the composite granulation, reduces the ash content and carbon loss rate of the activated carbon, has a simple process flow and low cost. And, the activated carbon particles are activated by partition atmosphere, effectively reconstructing the micropore and mesopore structure, so that the specific surface area and adsorption capacity of the regenerated activated carbon are significantly better than those of traditional regenerated products, solving the performance decline problem caused by carbon loss and structure collapse.

[0030] 3. The present application does not need to sort the waste cloth, nor does it need to deeply purify the powdered activated carbon, so the pretreatment step is simple, the labor and equipment investment are small, and it has good economic adaptability and cost control ability.

[0031] 4. By optimizing the granulation process and the design of the low-voltage arc ignition regeneration device, the present application can realize continuous batch processing, is suitable for activated carbon recycling enterprises, water treatment industry and waste gas purification system, and has good popularization and industrialization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The flow chart of the method of the present application.

[0033] Figure 2 The schematic diagram of the low-voltage arc ignition regeneration device for stepwise temperature zone regeneration and activation in the present application.

[0034] Figure 3 The comparative graph of the iodine adsorption value of the waste powder activated carbon and the columnar activated carbon after regeneration and activation and the ash content of the activated carbon in the embodiment of the present application. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described in detail below in combination with the drawings of the present application.

[0036] As shown in Figure 1 , the low-voltage arc ignition regeneration method of waste cloth and powder carbon composite granulation, the steps are as follows:

[0037] Step 1, collect the waste powder activated carbon generated in the water treatment process, which contains impurities (such as sludge). Put the waste powder activated carbon into the sedimentation tank, remove most of the impurities by sedimentation method, and get the product as the main raw material.

[0038] Step 2, collect waste cloth and crush it, then open it by an opener, and separate the waste cloth fiber raw material that can be used for granulation by a drum screen with a 5mm aperture.

[0039] Step 3, mix the waste cloth fiber raw material with the main raw material at a ratio of 1:4, and perform pyrolysis (150-300℃) and extrusion granulation in an extrusion granulator to form columnar particles. No external binder is added in this process, but the molten phase formed after pyrolysis of the waste cloth fiber raw material is used for bonding and granulation. This molten phase acts as a supplementary carbon source, not only reducing the proportion of activated carbon ash in the columnar particles, but also reinforcing the main raw material and its own pores (including macropores with a pore size greater than 50nm, mesopores with a pore size of 2-50nm and micropores with a pore size less than 2nm), and constructing new pores together with the main raw material. The columnar particles are dried at 150℃ for 4 hours to remove water, and columnar activated carbon with high mechanical strength is obtained.

[0040] Step 4, use as Figure 2The low-pressure arc ignition regeneration device shown regenerates and activates the columnar activated carbon in a stepwise temperature zone. In the low-temperature zone (45℃-450℃), with the desorption of water and volatile organic matter in the columnar activated carbon, a small part of the (previously blocked) pores in the columnar activated carbon can be reopened. In the medium-temperature zone (450℃-550℃), CO2 gas with a flow rate of 3L / min is introduced to promote the development of (new) micropores and keep the micropore channels clean. In the heating zone (550℃-750℃), with the pyrolysis and desorption of pyrolysis-type organic matter, most of the (previously blocked) pores in the columnar activated carbon can be quickly reopened. In the high-temperature zone (750℃-850℃), water vapor with a flow rate of 10L / min is introduced to achieve deep activation and (new) micropore construction. Finally, the regenerated activated carbon product with excellent adsorption performance is obtained.

[0041] To prove that the columnar activated carbon formed by compounding waste cloth and powdered carbon for granulation in the present application has the effect of improving the regeneration and activation effect of powdered activated carbon, the iodine adsorption value (iodine value) and activated carbon ash of the waste powdered activated carbon and the columnar activated carbon after low-pressure arc ignition regeneration are measured, and the comparison results are as shown in Figure 3 As can be seen from the comparison results, the columnar activated carbon after regeneration and activation by the method of the present application has a high iodine value and a low activated carbon ash, significantly improving the adsorption performance and recycling value of the activated carbon after regeneration and activation. Among them, the iodine adsorption value is a core index for measuring the degree of development of the micropore structure of activated carbon and the adsorption performance, which is directly related to the number of micropores, specific surface area and removal capacity of small molecular pollutants of activated carbon. The activated carbon ash refers to the inorganic content remaining after the activated carbon is burned at high temperature, usually expressed as a percentage by mass, which directly affects the purity and adsorption performance of activated carbon.

Claims

1. A low-voltage arc ignition method for recycling waste cloth and powder carbon composite granulation, characterized in that: The specific steps are as follows: ​ S1: The waste powdered activated carbon is put into a settling tank to remove impurities, and the obtained product is used as a main raw material; S2: After the waste cloth is collected, crushed and opened, the waste cloth fiber raw material is separated; S3: The waste cloth fiber raw material is mixed with the main raw material, pyrolysis and extrusion granulation are performed, the molten phase after pyrolysis of the waste cloth fiber raw material is used as a binder to realize binder granulation, forming columnar particles, and the molten phase serves as a supplementary carbon source, which not only reduces the proportion of activated carbon ash in the columnar particles, but also plays a role in reinforcing the main raw material and its own pores, and constructing new pores together with the main raw material; the columnar activated carbon is obtained after drying the columnar particles; S4: The columnar activated carbon is regenerated and activated in temperature zones using a low-pressure arc regeneration device, CO2 gas is introduced into the medium temperature zone at 450-550°C to promote the development of micropores and keep the micropore channels clean; water vapor is introduced into the high temperature zone at 750-850°C to realize deep activation and micropore structure construction, and finally the regenerated activated carbon product is obtained.

2. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The waste powdered activated carbon is generated during water treatment, waste gas treatment or soil remediation.

3. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: An opener is used for opening.

4. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: A drum screen is used to separate the waste cloth fiber raw material.

5. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The length of the waste cloth fiber raw material is not more than 5 mm.

6. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The waste cloth fiber raw material is mixed with the main raw material at a mass ratio of 1:

4.

7. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The diameter of the columnar activated carbon is 3 mm, and the length is 3-5 mm.

8. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The drying temperature is 150°C, and the drying time is 4 hours.

9. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: The CO2 gas flow introduced into the medium temperature zone is 3 L / min, and the water vapor flow introduced into the high temperature zone is 10 L / min.

10. The method for low-voltage arc ignition of waste cloth and powder carbon composite granulation according to claim 1, characterized in that: After step S4 is performed, the iodine adsorption value and activated carbon ash of the regenerated activated carbon product are measured.

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