Method for processing waste and old granular activated carbon of specific shape

Abstract

The application discloses a kind of waste special shape granular activated carbon processing method, to solve the technical problem of making special shape granular activated carbon as a kind of regenerative special shape granular activated carbon including columnar granular activated carbon again.It includes: waste special shape granular activated carbon is regenerated and handled;Waste special shape granular activated carbon after regeneration is handled and is crushed, and the crushing is used to crush waste special shape granular activated carbon after the regeneration into carbon powder;The carbon powder is mixed with liquid hole blocking agent to obtain first mixture;The first mixture is mixed with adhesive to obtain second mixture;The second mixture is injected into special shape granular material forming mold and is extruded from special shape granular material forming mold under the action of press machine to obtain special shape granular material;Special shape granular material is sequentially dried, carbonized and activated in order to obtain regenerative special shape granular activated carbon.

Description

Technical Field

[0001] This disclosure relates to the field of waste activated carbon treatment technology, specifically to a method for preparing mixed activated carbon, a method for treating mixed activated carbon, waste activated carbon of specific shapes, and a method for forming carbon powder. Background Technology

[0002] Generally, activated carbon loses its adsorption capacity after a period of use and becomes unusable; this activated carbon is then called spent activated carbon. If the spent activated carbon can be regenerated, it is either processed independently or by a specialized organization. This regeneration is usually offline, and methods typically include chemical regeneration and ultrasonic regeneration. If the spent activated carbon cannot be regenerated or the regenerated form does not meet usage requirements, it is generally disposed of as hazardous waste through rigid landfill or incineration, as stipulated in the "National Hazardous Waste List." Rigid landfill and incineration not only waste resources but also cause secondary pollution to the environment, thus contradicting the principles of sustainable development.

[0003] The activated carbon developed and produced by the applicant in this disclosure is mainly used as a desulfurization catalyst in catalytic flue gas desulfurization and a denitrification catalyst in flue gas SCR denitrification. The basic principle of catalytic flue gas desulfurization is that sulfur dioxide, water, and oxygen in the flue gas to be desulfurized are adsorbed onto the desulfurization catalyst and react under the catalytic action of the active components to generate sulfuric acid. When the sulfuric acid adhering to the desulfurization catalyst reaches a certain level, a regeneration solution (usually dilute sulfuric acid and / or water) can be used to wash the desulfurization catalyst, thereby removing the adhering sulfuric acid and releasing the active sites of the desulfurization catalyst. The principle of flue gas SCR denitrification is that when the flue gas to be denitrified and the mixed reducing agent pass through the denitrification catalyst, the nitrogen oxides in the flue gas to be denitrified are selectively reduced to nitrogen and water, thereby achieving the purpose of removing nitrogen oxides.

[0004] The aforementioned desulfurization and denitrification catalysts also face the challenge of disposing of spent activated carbon. Specifically, when the performance of spent desulfurization and denitrification catalysts still fails to meet requirements after regeneration using conventional methods, rigid landfill or incineration becomes necessary. The applicant has continuously tried new regeneration methods, but the results have consistently been unsatisfactory. Summary of the Invention

[0005] The inventors of this disclosure innovatively propose a method to address the problem that the performance of recycled activated carbon still fails to meet requirements. This method involves first using recycled activated carbon as raw material to manufacture regenerated activated carbon, and then mixing the regenerated activated carbon with benchmark activated carbon (i.e., pre-made activated carbon with superior performance) according to a predetermined mixing ratio to create a hybrid activated carbon. This hybrid activated carbon achieves a balance between usage cost and performance for users. However, in manufacturing regenerated activated carbon from recycled activated carbon, it was found that the recycled activated carbon is often severely deformed (e.g., broken). Regenerated activated carbon made from recycled activated carbon often requires secondary molding, which necessitates first crushing the recycled activated carbon into carbon powder, then mixing the carbon powder with a binder before secondary molding into a specific shape. However, the resulting specific-shaped blanks often have obvious defects such as burrs. Based on the above ideas and the technical problems encountered, the following invention is proposed.

[0006] One of the objectives of this invention is to provide a method for preparing mixed activated carbon and mixed activated carbon, so as to solve the technical problem that waste activated carbon is difficult to use due to unsatisfactory performance after regeneration.

[0007] The second objective of this invention is to provide a method for processing waste granular activated carbon of a specific shape, in order to solve the technical problem of producing a regenerated granular activated carbon of a specific shape, including columnar granular activated carbon.

[0008] The third objective of this invention is to provide a method for forming carbon powder to solve the technical problem of low quality of the blank after secondary forming of activated carbon powder (which can be from various types of waste activated carbon, such as waste powdered activated carbon used for water treatment, etc.), including the carbon powder produced in the above-mentioned method for treating waste activated carbon of specific shapes.

[0009] In a first aspect, a method for preparing a mixed activated carbon is provided, comprising: determining the intended use environment of the mixed activated carbon; determining an evaluation method for the performance of the mixed activated carbon based on the intended use environment; obtaining regenerated activated carbon, wherein the regenerated activated carbon is obtained by treating waste activated carbon, the treatment including regeneration treatment of the waste activated carbon; obtaining a reference activated carbon, wherein the reference activated carbon is a pre-made activated carbon whose performance is superior to that of the regenerated activated carbon; configuring the regenerated activated carbon and the reference activated carbon into mixed activated carbon samples according to different mixing ratios and evaluating them using the evaluation method to obtain a set mixing ratio; and configuring the regenerated activated carbon and the reference activated carbon into mixed activated carbon according to the set mixing ratio.

[0010] Secondly, a mixed activated carbon is provided, which is prepared by the method for preparing the mixed activated carbon of the first aspect described above.

[0011] The above-mentioned preparation method of mixed activated carbon and the mixed activated carbon provide an innovative way to utilize waste activated carbon, which can help users achieve a balance between the cost and effect of activated carbon use, and can also reduce the amount of waste activated carbon that is rigidly landfilled or incinerated, thereby reducing resource waste and environmental pollution.

[0012] Thirdly, a method for treating waste granular activated carbon of a specific shape is provided, comprising: regenerating the waste granular activated carbon of a specific shape, wherein the target material to be removed during the regeneration process is mainly the byproducts generated in the waste granular activated carbon of a specific shape during its previous use; crushing the regenerated waste granular activated carbon of a specific shape into carbon powder; mixing the carbon powder with a liquid plugging agent to obtain a first mixture, wherein the liquid plugging agent is used to prevent the adsorption of the carbon powder in the first mixture to a subsequent binder and can at least partially vaporize and volatilize during subsequent heating; mixing the first mixture with a binder to obtain a second mixture, wherein the binder is used to ensure the plasticity of the second mixture and can at least partially transform into carbonized material during subsequent carbonization; injecting the second mixture into a granular material forming mold and extruding granular material of a specific shape from the granular material forming mold under the action of a press; and sequentially drying, carbonizing, and activating the granular material of a specific shape to obtain regenerated granular activated carbon of a specific shape.

[0013] Fourthly, a method for molding carbon powder is provided, wherein the carbon powder is activated carbon powder and is used to prepare activated carbon of a specific shape after molding; the method includes: mixing the carbon powder with a liquid plugging agent to obtain a first mixture, wherein the liquid plugging agent is used to prevent the adsorption of the carbon powder in the first mixture to a subsequent binder and is at least partially vaporized and volatilized during the heating required to prepare the activated carbon of the specific shape; mixing the first mixture with a binder to obtain a second mixture, wherein the binder is used to ensure the plasticity of the second mixture and is at least partially converted into a carbonized material during the carbonization required to prepare the activated carbon of the specific shape; molding the second mixture to form a blank of a specific shape, wherein the activated carbon of the specific shape is obtained by sequentially drying, carbonizing and activating the blank of the specific shape.

[0014] The above-mentioned methods for treating waste activated carbon granules of specific shapes and for forming carbon powder solve the technical problem of obvious defects such as burrs in the blanks of specific shapes after mixing carbon powder with binder and performing secondary forming.

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages provided by the present invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice. Attached Figure Description

[0016] The accompanying drawings, which form part of this disclosure, are used to aid in understanding this disclosure. The contents provided in the drawings and their related descriptions in this disclosure may be used to interpret this disclosure, but do not constitute an undue limitation of this disclosure.

[0017] Figure 1 This is a schematic diagram of the structure of an industrial kiln flue gas purification system according to an embodiment of the present disclosure.

[0018] Figure 2 This is a schematic diagram of the structure of an SCR denitrification device according to an embodiment of the present disclosure. Detailed Implementation

[0019] The present disclosure will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present disclosure based on these descriptions. Before describing the invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0020] The technical solutions and features provided in the various sections, including the following description, can be combined with each other without conflict. Furthermore, where possible, these technical solutions, features, and related combinations can be given specific technical subject matter and protected by relevant patents.

[0021] The embodiments described below are generally only some embodiments and not all embodiments. All other embodiments obtained by those skilled in the art based on these embodiments without creative effort should fall within the scope of patent protection.

[0022] The terms "comprising," "including," and any variations thereof in this disclosure, the corresponding claims, and related parts are intended to cover non-exclusive inclusion. Other related terms and units can be reasonably interpreted based on the content provided in this disclosure.

[0023] The activated carbon developed and produced by the applicant in this disclosure is mainly used as a desulfurization catalyst for catalytic flue gas desulfurization and a denitrification catalyst for flue gas SCR denitrification.

[0024] The basic principle of catalytic flue gas desulfurization is as follows: sulfur dioxide, water, and oxygen in the flue gas to be desulfurized are adsorbed on the desulfurization catalyst and react under the catalytic action of the active components to generate sulfuric acid; when the sulfuric acid attached to the desulfurization catalyst reaches a certain level, the desulfurization catalyst can be washed with a regeneration liquid (usually dilute sulfuric acid and / or water) to remove the attached sulfuric acid and release the active sites of the desulfurization catalyst.

[0025] The principle of flue gas SCR denitrification is: when the flue gas to be denitrified and the mixed reducing agent pass through the denitrification catalyst, the nitrogen oxides in the flue gas to be denitrified are selectively reduced and converted into nitrogen and water, thereby achieving the purpose of removing nitrogen oxides.

[0026] The following section will first describe a specific application scenario of the aforementioned desulfurization and denitrification catalysts in order to provide a more comprehensive understanding of the contents of this disclosure.

[0027] Figure 1 This is a schematic diagram of the structure of an industrial kiln flue gas purification system according to an embodiment of the present disclosure. Figure 2 This is a schematic diagram of the structure of an SCR denitrification device according to an embodiment of this disclosure. Figures 1-2 As shown, the industrial kiln flue gas purification system of this embodiment includes at least: a catalytic flue gas desulfurization module 3, a low-temperature SCR denitrification module 4, and a heat exchange module 2. This industrial kiln flue gas purification system provides an integrated desulfurization and denitrification solution with a wide range of applications, covering numerous industrial kiln flue gas desulfurization and denitrification scenarios.

[0028] The catalytic flue gas desulfurization module 3 includes a desulfurization reactor. The desulfurization reactor has an inlet for the flue gas to be desulfurized, an outlet for the desulfurized flue gas, a outlet for the desulfurization catalyst regeneration liquid, and a desulfurization catalyst loading space located in the desulfurization reactor. The desulfurization reactor is equipped with a desulfurization catalyst regeneration liquid spraying device for washing and regenerating the desulfurization catalyst in the desulfurization catalyst loading space. During desulfurization, the flue gas enters the desulfurization reactor from the inlet for the flue gas to be desulfurized, is desulfurized by the desulfurization catalyst, and is then discharged from the outlet for the desulfurized flue gas. When the sulfur dioxide in the flue gas passes through the desulfurization catalyst, it reacts on the desulfurization catalyst to form sulfuric acid. When the desulfurization catalyst is washed and regenerated, the sulfuric acid enters the desulfurization catalyst regeneration liquid and is discharged from the outlet for the desulfurization catalyst regeneration liquid.

[0029] The low-temperature SCR denitrification module 4 includes an SCR denitrification reactor 43 and a mixer 41 (used to mix a reducing agent such as ammonia with flue gas) located before the SCR denitrification reactor 43. The SCR denitrification reactor 43 has a flue gas inlet for denitrification, a flue gas outlet for denitrification, and a denitrification catalyst filling space located in the SCR denitrification reactor. The denitrification catalyst filling space is used to fill the denitrification catalyst. The operating temperature of the denitrification catalyst is 120℃-200℃ (therefore, the denitrification catalyst is called a low-temperature denitrification catalyst). During denitrification, the flue gas mixed with the denitrification reducing agent enters the SCR denitrification reactor from the flue gas inlet for denitrification, then passes through the denitrification catalyst for denitrification, and is then discharged from the flue gas outlet for denitrification.

[0030] The heat exchange module 2 includes a first heat exchanger 21, which has a first flue gas inlet to be cooled, a first flue gas exhaust outlet, a first flue gas inlet to be heated, a first flue gas exhaust outlet, and a first heat exchanger first heat exchanger channel and a first heat exchanger second heat exchanger channel located in the first heat exchanger 21 for indirect heat exchange. The two ends of the first heat exchanger first heat exchanger channel are respectively connected to the first flue gas inlet to be cooled and the first flue gas exhaust outlet, and the two ends of the first heat exchanger second heat exchanger channel are respectively connected to the first flue gas inlet to be heated and the first flue gas exhaust outlet.

[0031] Furthermore, in the industrial kiln flue gas purification system of this embodiment, the first flue gas inlet to be cooled is used to connect to the industrial kiln flue gas source, the first cooled flue gas exhaust port is used to connect to the flue gas inlet to be desulfurized, the desulfurized flue gas exhaust port is used to connect to the first flue gas inlet to be heated, the first heated flue gas exhaust port is used to connect to the flue gas inlet to be denitrified, and the denitrified flue gas exhaust port is used to output the denitrified flue gas to the industrial kiln flue gas purification system.

[0032] Generally speaking, the temperature of the flue gas to be desulfurized at the flue gas inlet can be 50℃-100℃; the temperature of the heated flue gas at the first heated flue gas outlet can be 120℃-220℃.

[0033] The working principle of the industrial kiln flue gas purification system in this embodiment is as follows: high-temperature flue gas (e.g., 130℃-170℃) from the industrial kiln flue gas source enters the first heat exchanger 21 from the first flue gas inlet to be cooled. The first heat exchanger 21 discharges the cooled flue gas (e.g., 60℃-80℃) from the first cooled flue gas outlet. The cooled flue gas enters the catalytic flue gas desulfurization module 3 as the flue gas to be desulfurized. The desulfurized flue gas output from the catalytic flue gas desulfurization module 3 returns to the first heat exchanger 21 from the first flue gas inlet to be heated. The first heat exchanger 21 discharges the heated flue gas (e.g., 120℃-160℃) from the first heated flue gas outlet. The heated flue gas enters the low-temperature SCR denitrification module 4 as the flue gas to be denitrified. The low-temperature SCR denitrification module 4 outputs the denitrified flue gas. In the first heat exchanger 21, the high-temperature flue gas from the industrial kiln source indirectly exchanges heat with the low-temperature desulfurized flue gas output from the catalytic flue gas desulfurization module 3. Therefore, the industrial kiln flue gas purification system of this embodiment reduces the temperature of the flue gas to be desulfurized through the first heat exchanger 21; on the other hand, it can also raise the temperature of the flue gas to be denitrified to the temperature range required by the low-temperature SCR denitrification module 3. Since the first heat exchanger 21 indirectly exchanges heat between the high-temperature flue gas from the industrial kiln source and the low-temperature desulfurized flue gas output from the catalytic flue gas desulfurization module 3, the heating of the flue gas to be denitrified does not generate excess energy consumption.

[0034] like Figure 1 As shown, in the industrial kiln flue gas purification system of this embodiment, when the temperature of the flue gas from the industrial kiln flue gas source is too high, for example, exceeding 170°C (such as coke oven flue gas), a second heat exchanger 22 can be set in the heat exchange module 2. The second heat exchanger 22 has a second flue gas inlet to be cooled and a second cooled flue gas outlet. The first cooled flue gas outlet is used to connect to the second flue gas inlet to be cooled, and the second cooled flue gas outlet is used to connect to the flue gas inlet to be desulfurized. The second heat exchanger 22 can be a waste heat boiler. The function of the second heat exchanger 22 is that when the temperature of the flue gas from the industrial kiln flue gas source is too high, by further recovering the heat of the flue gas, both waste heat is effectively utilized, and the temperature of the flue gas to be desulfurized and the flue gas to be denitrified can be controlled within an ideal range. In order to control the direction of the first heat exchanger 21 or the flue gas outlet, a control valve 23 is also provided between the first heat exchanger 21 and the second heat exchanger 22.

[0035] like Figure 1As shown, the industrial kiln flue gas purification system of this embodiment typically includes a dust removal module 1. The dust removal module 1 includes a dry flue gas dust collector, which is connected to the first flue gas inlet to be cooled, removing dust from the flue gas sourced from the industrial kiln before conveying it to the first flue gas inlet to be cooled. The dry flue gas dust collector can be an electrostatic precipitator, an electrostatic bag filter, a bag filter, a ceramic filter, or a metal filter, etc. Generally, the dust removal module 1 needs to control the dust content in the output flue gas to within 50 mg / Nm³. 3 This ensures the heat exchange efficiency of heat exchange module 2 (if the dust content in the flue gas is too high, dust will adhere to the pipes in heat exchange module 2, affecting the heat exchange efficiency), and also prevents dust from clogging the desulfurization catalyst in catalytic flue gas desulfurization module 3, thereby increasing the operating resistance of the industrial kiln flue gas purification system and affecting the desulfurization efficiency and the quality of sulfuric acid by-products.

[0036] like Figure 2 As shown, the low-temperature SCR denitrification module 4 also includes an SCR denitrification pretreatment device 42. The SCR denitrification pretreatment device 42 includes a pretreatment reactor, which has an inlet for the flue gas to be pretreated, an outlet for the pretreated flue gas, a outlet for the pretreated catalyst regeneration liquid, and a pretreatment catalyst loading space within the pretreatment reactor. The pretreatment reactor is equipped with a pretreatment catalyst regeneration liquid spraying device (similar to a desulfurization catalyst regeneration liquid spraying device in catalytic flue gas desulfurization) for washing and regenerating the pretreatment catalyst in the pretreatment catalyst loading space. The operating temperature of the pretreatment catalyst is 120℃-200℃. During pretreatment, flue gas mixed with a pretreatment reducing agent enters the SCR pretreatment reactor from the inlet for the flue gas to be pretreated, is pretreated by the pretreatment catalyst, and then exits from the outlet for the pretreated flue gas. During the washing and regeneration of the pretreatment catalyst, the pretreatment catalyst regeneration liquid is discharged from the outlet for the pretreatment catalyst regeneration liquid.

[0037] In the low-temperature SCR denitrification module 4, the pretreatment reactor of the SCR denitrification pretreatment device 42 can reduce the content of dust and sulfur dioxide (in small amounts) in the flue gas to be denitrified by utilizing the adsorption and other effects of the pretreatment catalyst. The pretreatment catalyst in the pretreatment reactor of the SCR denitrification pretreatment device 42 also uses a columnar granular activated carbon. The pretreatment reactor of the SCR denitrification pretreatment device 42 can further remove sulfur dioxide from the flue gas to be denitrified by utilizing the principle of catalytic flue gas desulfurization (i.e., sulfur dioxide, water, and oxygen in the flue gas to be denitrified are adsorbed on the pretreatment catalyst to generate sulfuric acid), thereby avoiding the ammonium sulfate generated by the reaction of sulfur dioxide with the denitrification reducing agent (usually NH3) from entering the denitrification catalyst and affecting denitrification. By periodically washing and regenerating the pretreatment catalyst in the pretreatment reactor of the SCR denitrification pretreatment device 42 (the regeneration principle is the same as that of catalytic flue gas desulfurization), the activity of the pretreatment catalyst can be restored. Therefore, the low-temperature SCR denitrification module 4 combines the SCR denitrification pretreatment device 42 with the SCR denitrification device 32, which helps to improve the denitrification efficiency. Engineering practice shows that when the SCR denitrification pretreatment device 42 is used in combination with the SCR denitrification device 32, the denitrification efficiency can reach ≥90%.

[0038] The aforementioned desulfurization catalyst, denitrification catalyst, and pretreatment catalyst each utilize different columnar granular activated carbon. The composition and properties of these catalysts vary depending on their respective application environments.

[0039] The aforementioned desulfurization catalysts, denitrification catalysts, and pretreatment catalysts have long service lives, but the disposal of spent activated carbon remains a challenge. Users are particularly concerned about the operating costs of these catalysts, especially the periodic replacement costs. Therefore, the following methods for treating spent activated carbon are proposed to address the specific needs of the desulfurization, denitrification, and pretreatment catalysts, thereby helping to reduce the periodic replacement costs.

[0040] For ease of description, based on their application, desulfurization catalysts are referred to as activated carbon for desulfurization catalysts, denitrification catalysts as activated carbon for denitrification catalysts, and pretreatment catalysts as activated carbon for pretreatment catalysts. Activated carbon for desulfurization catalysts can be further categorized into activated carbon for spent desulfurization catalysts, activated carbon for regenerated desulfurization catalysts, activated carbon for standard desulfurization catalysts, and activated carbon for mixed desulfurization catalysts. The rest follow the same pattern.

[0041] Treatment of activated carbon from spent desulfurization catalysts

[0042] 1.1 Determination of the mixing ratio of activated carbon for mixed desulfurization catalysts.

[0043] First, based on the operational requirements of the catalytic flue gas desulfurization module 3, a performance evaluation method for activated carbon used in the mixed desulfurization catalyst was determined.

[0044] The performance of activated carbon for mixed desulfurization catalysts is evaluated using two indicators: sulfur capacity and average crushing strength. Sulfur capacity refers to the weight of sulfur absorbed per unit weight of desulfurizing agent, expressed as a percentage (%). Average crushing strength is used to evaluate the performance of activated carbon for mixed desulfurization catalysts, measured in Newtons per centimeter (N / cm).

[0045] Secondly, the spent desulfurization catalyst is processed into regenerated desulfurization catalyst activated carbon using activated carbon. This specifically includes the following operations / steps / processes:

[0046] I. Regeneration treatment of the activated carbon used in the waste desulfurization catalyst, wherein the target substances to be removed in the regeneration treatment are mainly the products generated in the activated carbon used in the waste desulfurization catalyst during previous use.

[0047] The products generated here are mainly acidic substances, such as certain sulfates, generated from the activated carbon in the waste desulfurization catalyst during previous use.

[0048] Preferably, the regeneration process includes heating the spent desulfurization catalyst with activated carbon at a temperature of 800℃-1000℃ in the absence of oxygen. Experiments show that heating the spent desulfurization catalyst with activated carbon at a temperature of 800℃-1000℃ in the absence of oxygen has a significantly better regeneration effect than conventional water washing regeneration methods and ultrasonic regeneration methods.

[0049] Experiment on regeneration treatment of spent desulfurization catalysts with activated carbon

[0050] Used activated carbon from waste desulfurization catalysts (containing ash on the surface, with an ash content of approximately 10%, complex physical properties, and a sulfur capacity of only 1%-2% as tested) was dried to constant weight at 110℃ and set aside. The waste activated carbon was then regenerated using four methods: water washing regeneration, ultrasonic regeneration, heating at 800℃-1000℃ in the absence of oxygen for 1 hour (referred to as thermal regeneration), and water washing regeneration followed by ultrasonic regeneration and finally heating at 800℃-1000℃ in the absence of oxygen for 1 hour (referred to as water washing + ultrasonic + thermal regeneration). The sulfur capacity of each method was then tested.

[0051] Table 1: Sulfur Capacity After Different Regeneration Methods

[0052]

[0053] The results showed that the activated carbon used for recycling spent desulfurization catalysts had a very low sulfur capacity. Water washing regeneration restored the sulfur capacity to 6.6%, ultrasonic cleaning regeneration to 9.4%, and thermal regeneration to 23.3%. To verify the effectiveness and level of thermal regeneration, a control experiment was designed using a combination of water washing, ultrasonic cleaning, and thermal regeneration. The results of this experiment were used as the limiting sulfur capacity after regeneration with activated carbon from spent desulfurization catalysts, which was 26.1%.

[0054] The sulfur capacity after thermal regeneration is 23%, while the sulfur capacity after a combination of water washing, ultrasonic cleaning, and thermal regeneration is 26.1%. The difference in sulfur capacity between the two is only 2.8%. From the perspective of simplicity, practicality, and economy, thermal regeneration is considered sufficient to meet the requirements for regenerating spent desulfurization catalysts with activated carbon.

[0055] The pore structure of activated carbon used in the regenerated waste desulfurization catalyst is shown in Table 2. As can be seen from Table 2, the specific surface area of ​​the activated carbon used in the waste desulfurization catalyst is 705 m². 2 / g, water washing regeneration, ultrasonic cleaning regeneration, and thermal regeneration can all improve its specific surface area and corresponding pore structure performance indicators. However, the improvement is not commensurate with the corresponding sulfur capacity. Analysis shows that this may be because the activated carbon used in waste desulfurization catalysts has a high ash and acid content, which occupies the pores inside the carbon material and blocks the channels connecting the pores, thus resulting in the low desulfurization performance of the activated carbon used in waste desulfurization catalysts.

[0056] Both water washing and ultrasonic cleaning can effectively remove the accumulated ash inside the activated carbon of spent desulfurization catalysts to varying degrees (the ash content of the activated carbon itself is 10%, while the ash content of the activated carbon after water washing and ultrasonic cleaning is around 7%), and also remove some acid, thus significantly improving desulfurization performance. Thermal treatment regeneration primarily removes acidic substances from the activated carbon inside the spent desulfurization catalysts (the mass of the treated activated carbon is reduced by 10%), resulting in a sulfur capacity of 23%, which is a significant improvement compared to water washing and ultrasonic cleaning.

[0057] Therefore, it can be concluded that the performance degradation of activated carbon used in waste desulfurization catalysts is mainly due to the presence of a large amount of acidic substances in the activated carbon itself; ash and other impurities also have a significant impact on desulfurization performance.

[0058] In summary, the desulfurization capacity of activated carbon from spent desulfurization catalysts is low. However, the desulfurization capacity of activated carbon from spent desulfurization catalysts is significantly improved after water washing, ultrasonic cleaning, and thermal regeneration. Comparatively, thermal regeneration can restore the original sulfur capacity of activated carbon from spent desulfurization catalysts to a greater extent. It is simple to operate and economical, making it an ideal regeneration process for activated carbon from spent desulfurization catalysts. Analysis of the pore structure and ash content of samples treated by various methods reveals that ash accumulation and acidic substances inside the carbon material are the main reasons for the decrease in sulfur capacity of activated carbon from spent desulfurization catalysts. Among these, the impact of residual acidic substances is greater than that of ash accumulation.

[0059] Table 2: Pore structure after treatment with different regeneration methods

[0060]

[0061] II. The spent desulfurization catalyst activated carbon that has undergone regeneration treatment is crushed into carbon powder.

[0062] Generally speaking, the crushing process involves crushing the carbon powder to pass through a 200-mesh sieve.

[0063] III. The carbon powder is mixed with a liquid plugging agent to obtain a first mixture, wherein the liquid plugging agent is used to prevent the carbon powder in the first mixture from adsorbing the subsequent binder and can at least partially vaporize and volatilize during subsequent heating.

[0064] IV. The first mixture is mixed with a binder to obtain a second mixture, wherein the binder is used to ensure the plasticity of the second mixture and to enable it to be at least partially converted into carbonized material during subsequent carbonization.

[0065] V. The second mixture is shaped into a blank of a specific shape.

[0066] The inventors discovered that activated carbon from spent desulfurization catalysts often suffers from severe deformation (such as breakage). When manufacturing regenerated activated carbon using this spent activated carbon as raw material, secondary molding is often required. This secondary molding necessitates first crushing the regenerated spent desulfurization catalyst into activated carbon powder, then mixing the powder with a binder before secondary molding into a billet. However, the billet produced in this way exhibits significant defects such as burrs. Research revealed that the main reason for these defects is the strong adsorption capacity (high iodine value) of the carbon powder, leading to uneven adsorption of the binder. This uneven mixing of the binder results in poor billet quality.

[0067] After mixing the carbon powder with a liquid plugging agent to obtain a first mixture, the liquid plugging agent can quickly seal the micropores on the surface of the carbon powder, thereby hindering the adsorption of the carbon powder in the first mixture by the subsequent binder. Furthermore, the liquid plugging agent can at least partially vaporize and volatilize during subsequent heating to create pores, thereby increasing the porosity of the regenerated desulfurization catalyst. Subsequently, the first mixture is mixed with a binder to obtain a second mixture. The binder ensures the plasticity of the second mixture and can at least partially transform into carbonized material during subsequent carbonization, thereby compensating for the mass loss during the regeneration of the spent desulfurization catalyst using activated carbon.

[0068] Preferably, the liquid plugging agent comprises at least one of CMC solution and silica sol. CMC solution and silica sol themselves can also act as binders; therefore, when the liquid plugging agent comprises at least one of CMC solution and silica sol, it helps to improve molding quality. Furthermore, when the liquid plugging agent comprises silica sol, the silica sol transforms into silica during subsequent carbonization. Silica has strong corrosion resistance and helps to improve the strength and specific surface area of ​​the regenerated desulfurization catalyst.

[0069] Optionally, the binder comprises coal tar. Coal tar is a commonly used binder that ensures the plasticity of the second mixture. Furthermore, the coal tar is simultaneously carbonized during the subsequent carbonization process, thereby compensating for the mass loss during the regeneration of waste activated carbon.

[0070] Generally, when the liquid plugging agent is composed of at least one of CMC solution and silica sol, and the adhesive is composed of coal tar, the ratio of the amounts of the carbon powder, the liquid plugging agent, and the adhesive is: mass of carbon powder : mass of liquid plugging agent : mass of adhesive = 1 : (0.3-1) : (0.5-1.5); wherein the mass percentage concentration of the CMC solution is 5%-25%, and the mass percentage concentration of silica in the silica sol is 10%-35%.

[0071] Preferably, the ratio of the amount of carbon powder, the liquid plugging agent and the adhesive is: mass of carbon powder: mass of liquid plugging agent: mass of adhesive = 1:(0.4-0.6):(1-1.5).

[0072] Optionally, the liquid plugging agent is composed of a CMC solution and a silica sol; the mass ratio of the CMC solution to the silica sol is 0.5-1.5.

[0073] Specifically, molding the second mixture into a blank of a specific shape includes: injecting the second mixture into a mold for forming granules of a specific shape and extruding granules of a specific shape from the mold under the action of a press.

[0074] The "specifically shaped granules" in the process of injecting the second mixture into a specific-shaped granule molding die and extruding the specific-shaped granules from the die under the action of a press are specifically columnar granules.

[0075] Optionally, the press is a vertical hydraulic press, and the granule forming mold of the specific shape includes a spray plate installed at the outlet of the vertical hydraulic press during use, the spray plate being densely covered with granule forming holes of the specific shape.

[0076] Of course, in other possible implementations, molding the second mixture into a blank of a specific shape includes: injecting the second mixture into a honeycomb blank forming mold and extruding the honeycomb blank from the honeycomb blank forming mold under the action of a press.

[0077] VI. The specific shaped granular material is successively dried, carbonized, and activated to obtain regenerated activated carbon for desulfurization catalyst.

[0078] Optionally, the carbonization temperature is 600℃-1000℃ and the time is 1 hour-3 hours. Preferably, the carbonization temperature is 800℃-850℃.

[0079] Activation is performed using steam for 1 hour at a temperature of 600℃.

[0080] Experiment on activated carbon preparation for char powder molding and regenerable desulfurization catalyst

[0081] The purpose of this experiment is to obtain regenerated activated carbon for desulfurization catalyst by secondary molding of carbon powder and sequential drying, carbonization and activation in an economical and feasible manner, and to test the desulfurization performance (sulfur capacity) and strength index (average crushing strength) of the regenerated activated carbon for desulfurization catalyst.

[0082] The spent desulfurization catalyst that has undergone thermal regeneration is crushed using activated carbon: pulverized and passed through a 200-mesh sieve, the resulting carbon powder is set aside. The carbon powder is divided into multiple portions, and each portion is subjected to secondary molding using different methods (molding with a 4mm aperture and 15mm thickness spray plate) to obtain various different columnar granular materials (samples). These samples are then used to prepare activated carbon for regenerated desulfurization catalysts.

[0083] Table 3: Performance of Activated Carbon for Regenerated Desulfurization Catalysts with Different Sample Molding Ratios

[0084]

[0085]

[0086]

[0087] Note: The samples of Comparative Example 1 and Comparative Example 2 were directly processed at 800℃ for 2 hours to obtain regenerated activated carbon for desulfurization catalyst. Since the regenerated activated carbon for desulfurization catalyst prepared in Comparative Example 1 softens and disperses when exposed to water and is not usable, the strength of the regenerated activated carbon for desulfurization catalyst prepared in Comparative Example 1 was not tested.

[0088] The regenerated desulfurization catalyst activated carbon from Example 6 was obtained for later use as the regenerated desulfurization catalyst activated carbon for the subsequent preparation of mixed desulfurization catalyst activated carbon.

[0089] Subsequently, a reference-type activated carbon for desulfurization catalyst is obtained, wherein the reference-type activated carbon for desulfurization catalyst is a pre-formulated activated carbon whose performance is superior to that of the regenerated activated carbon for desulfurization catalyst. Here, the reference-type activated carbon for desulfurization catalyst has a sulfur capacity of 25% and a strength of 160 N / cm.

[0090] Then, the activated carbon for the regenerated desulfurization catalyst and the activated carbon for the reference desulfurization catalyst were respectively prepared into mixed desulfurization catalyst activated carbon samples according to different mixing ratios and evaluated using the evaluation method to obtain the set mixing ratio.

[0091] The different mixing ratios refer to the volume ratio of activated carbon used in regenerated desulfurization catalysts to activated carbon used in reference desulfurization catalysts. This volume ratio is used to align with the loading volume of the mixed desulfurization catalyst activated carbon in actual engineering applications, ensuring that the evaluation results of the mixed desulfurization catalyst activated carbon samples better reflect the actual engineering application effects.

[0092] The process of preparing mixed desulfurization catalyst activated carbon samples by mixing the regenerated desulfurization catalyst activated carbon and the reference desulfurization catalyst activated carbon in different mixing ratios and then evaluating them using the evaluation method includes:

[0093] Set a standard volume for activated carbon samples of mixed desulfurization catalysts, and then make the total volume of activated carbon samples of mixed desulfurization catalysts prepared according to different volume ratios equal to the standard volume of the activated carbon samples of mixed desulfurization catalysts.

[0094] The activated carbon samples for each type of mixed desulfurization catalyst were evaluated to obtain their respective performance characteristics.

[0095] The activated carbon for the regenerated desulfurization catalyst and the activated carbon for the reference desulfurization catalyst were prepared into mixed activated carbon samples for desulfurization catalysts according to different mixing ratios, and the samples were evaluated, including:

[0096] During the preparation of each mixed desulfurization catalyst activated carbon sample, the mass ratio of the regenerated desulfurization catalyst activated carbon to the reference desulfurization catalyst activated carbon corresponding to the mixed desulfurization catalyst activated carbon sample is obtained by weighing at least two of the three: the required volume of regenerated desulfurization catalyst activated carbon, the required volume of reference desulfurization catalyst activated carbon, and the mixed desulfurization catalyst activated carbon sample.

[0097] At this point, the set mixing ratio refers to the mass ratio of activated carbon used in the regenerable desulfurization catalyst to activated carbon used in the standard desulfurization catalyst. By converting the set mixing ratio into a mass ratio, it is easier to subsequently prepare the activated carbon for the mixed desulfurization catalyst.

[0098] Optionally, a container with a volume of 1 / N of the standard volume of the activated carbon sample for the mixed desulfurization catalyst can be prepared according to the standard volume of the activated carbon sample for the mixed desulfurization catalyst, where N is an integer ≥3 and ≤100. Then, when preparing the activated carbon sample for the mixed desulfurization catalyst, the container can be used to measure the activated carbon for the regenerated desulfurization catalyst and the activated carbon for the reference desulfurization catalyst in N separate measurements.

[0099] Experiment on the preparation of activated carbon for mixed desulfurization catalyst

[0100] Table 4: Sulfur Capacity of Reference Samples with Different Proportions of Carbon Samples

[0101]

[0102] Test results show that as the proportion of activated carbon in the regenerated desulfurization catalyst increases, the sulfur capacity of the activated carbon in the mixed desulfurization catalyst gradually decreases. Finally, the mixing ratio was determined using a combination of "30% FQ-1 + 70% reference sample".

[0103] 1.2 The regenerated desulfurization catalyst activated carbon and the standard desulfurization catalyst activated carbon are mixed according to a set mixing ratio and configured into a mixed desulfurization catalyst activated carbon.

[0104] Treatment of activated carbon from spent denitrification catalysts

[0105] The spent denitrification catalyst activated carbon was treated in a similar manner to the spent desulfurization catalyst activated carbon mentioned above to obtain a mixed type of denitrification catalyst activated carbon.

[0106] Treatment of activated carbon used in waste pretreatment catalysts

[0107] The pretreatment catalyst activated carbon is obtained by combining a portion of the regenerated desulfurization catalyst activated carbon obtained during the treatment of the aforementioned waste desulfurization catalyst activated carbon with a portion of the regenerated denitrification catalyst activated carbon obtained during the treatment of the aforementioned waste denitrification catalyst activated carbon. The volume ratio of the regenerated desulfurization catalyst activated carbon to the regenerated denitrification catalyst activated carbon is preferably set to 1.5-9.

[0108] The foregoing has described the relevant content of the present invention. Those skilled in the art will be able to implement the present invention based on these descriptions. All other embodiments obtained by those skilled in the art based on the foregoing content of this specification without inventive effort should fall within the scope of the present invention.

Claims

1. A method for treating waste activated carbon of a specific shape, characterized in that: include: The waste granular activated carbon of a specific shape is regenerated, and the target material to be removed in the regeneration process is mainly the product generated in the waste granular activated carbon of a specific shape during its previous use. The waste granular activated carbon of a specific shape that has undergone regeneration is crushed into carbon powder. The carbon powder is mixed with a liquid plugging agent to obtain a first mixture. The liquid plugging agent contains at least one of CMC solution and silica sol. The liquid plugging agent is used to prevent the carbon powder in the first mixture from adsorbing the subsequent binder and can at least partially vaporize and volatilize during subsequent heating. The first mixture is mixed with a binder to obtain a second mixture, wherein the binder contains coal tar and is used to ensure the plasticity of the second mixture and to enable it to be at least partially converted into carbonized material during subsequent carbonization; The ratio of the amounts of the carbon powder, the liquid plugging agent, and the adhesive is: carbon powder mass : liquid plugging agent mass : adhesive mass = 1 : (0.3-1) : (0.5-1.5); wherein, the mass percentage concentration of the CMC solution is 5%-25%, and the mass percentage concentration of silica in the silica sol is 10%-35%; The second mixture is injected into a granule molding die of a specific shape and extruded into granules of a specific shape under the action of a press. The specific shaped granules are sequentially dried, carbonized, and activated to obtain regenerated specific shaped granular activated carbon.

2. The method for treating waste granular activated carbon of a specific shape as described in claim 1, characterized in that: Both the waste-grade granular activated carbon and the recycled granular activated carbon are used as desulfurization catalysts, denitrification pretreatment agents, or denitrification catalysts; and / or, the granular material of the specific shape is columnar granular material.

3. The method for treating waste granular activated carbon of a specific shape as described in claim 2, characterized in that: Both the spent granular activated carbon and the regenerated granular activated carbon serve as desulfurization catalysts; therefore, the main target substances removed during the regeneration process are the acidic substances generated in the spent granular activated carbon during its previous use.

4. The method for treating waste granular activated carbon of a specific shape as described in claim 3, characterized in that: The regeneration process includes heating waste activated carbon of a specific shape in the absence of oxygen at a temperature of 800°C-1000°C.

5. The method for treating waste granular activated carbon of a specific shape as described in claim 3, characterized in that: Also includes: The regenerated granular activated carbon of a specific shape and the standard granular activated carbon of a specific shape are mixed in a set mixing ratio to form a mixed granular activated carbon of a specific shape. The reference type specific shape granular activated carbon is a pre-made specific shape granular activated carbon whose desulfurization performance under the intended use environment of the mixed type specific shape granular activated carbon is superior to that of the regenerated type specific shape granular activated carbon.

6. The method for treating waste granular activated carbon of a specific shape as described in claim 5, characterized in that: The set mixing ratio is determined through testing of mixed-type specific-shape granular activated carbon; the testing of mixed-type specific-shape granular activated carbon includes: The regenerated granular activated carbon of a specific shape and the reference granular activated carbon of a specific shape were respectively prepared into mixed granular activated carbon samples according to different mixing ratios, and their desulfurization performance was evaluated. Wherein, the different mixing ratios refer to the volume ratio of regenerated granular activated carbon of a specific shape to that of standard granular activated carbon of a specific shape; The regenerated granular activated carbon of a specific shape and the reference granular activated carbon of a specific shape were respectively prepared into mixed granular activated carbon samples according to different mixing ratios, and their desulfurization performance was evaluated, including: Set a standard volume for a mixed-type granular activated carbon sample with a specific shape, and then make the total volume of mixed-type granular activated carbon samples with different volume ratios equal to the standard volume of the mixed-type granular activated carbon sample. The desulfurization performance of each mixed-type granular activated carbon sample with a specific shape was evaluated, and the desulfurization performance of each sample was obtained.

7. The method for treating waste granular activated carbon of a specific shape as described in claim 6, characterized in that: The set mixing ratio refers to the mass ratio of regenerated granular activated carbon of a specific shape to that of standard granular activated carbon of a specific shape; then The regenerated granular activated carbon of a specific shape and the reference granular activated carbon of a specific shape were respectively prepared into mixed activated carbon samples according to different mixing ratios, and their desulfurization performance was evaluated, including: During the preparation of each mixed-type specific-shape granular activated carbon sample, the mass ratio of the regenerated specific-shape granular activated carbon to the reference specific-shape granular activated carbon corresponding to the mixed-type specific-shape granular activated carbon sample is obtained by weighing at least two of the three: the required volume of regenerated specific-shape granular activated carbon, the required volume of reference specific-shape granular activated carbon, and the mixed-type specific-shape granular activated carbon sample.

8. The method for treating waste granular activated carbon of a specific shape as described in claim 6, characterized in that: Prepare a container with a volume of 1 / N of the standard volume of the mixed-type specific-shape granular activated carbon sample, where N is an integer ≥3 and ≤100. Then, when preparing the mixed-type specific-shape granular activated carbon sample, use this container to measure the regenerated specific-shape granular activated carbon and the reference specific-shape granular activated carbon in N separate measurements.

9. The method for treating waste granular activated carbon of a specific shape as described in any one of claims 1-8, characterized in that: The press is a vertical hydraulic press, and the granule forming mold of the specific shape includes a spray plate installed at the outlet of the vertical hydraulic press during use, and the spray plate is densely covered with granule forming holes of the specific shape.

Images