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Guide for Standardized Management of Activated Carbon Treatment Process


Time:

2022-10-14

Activated carbon adsorption is a commonly used method to treat volatile organic compounds (VOCs) in industrial enterprises. The self inspection guide for standardized management of activated carbon adsorption treatment process in gas related enterprises is coming!

In the organic waste gas treatment process, the activated carbon treatment method is widely used, and there are also many problems, such as the mismatch between the design air volume and the treated waste gas, unreasonable equipment structure, the replacement of defective activated carbon, the gas flow rate of the adsorption layer does not meet the standard, and the replacement of activated carbon is not timely, which greatly reduces the treatment effect.


Activated carbon adsorption is a commonly used method to treat volatile organic compounds (VOCs) in industrial enterprises. It is widely used because activated carbon has the following characteristics:
1. Activated carbon has large specific surface area and adsorption capacity, good mechanical strength, chemical stability and thermal stability, and can be regenerated repeatedly.
2. According to different forms, activated carbon can be divided into granular activated carbon, honeycomb activated carbon and powdered activated carbon, which can be applied to different process conditions.

 

Self inspection guide for standardized management of activated carbon adsorption treatment process in gas related enterprises

01 Design air volume
The VOCs emission process shall be operated in a confined space or collected with a fully enclosed gas collecting hood. If it is impossible to use a partial gas collecting hood in a closed manner, the collection point shall be reasonably selected according to the characteristics of exhaust gas emission. According to the Classification and Technical Conditions of Exhaust Hood (GB/T 16758), a gas collecting hood capable of effectively collecting exhaust gas shall be set. The VOCs unorganized emission position farthest from the opening surface of the gas collecting hood shall be set, and the wind speed shall be controlled at least 0.3m/s.
The fan of the activated carbon adsorption device shall meet the needs of the air volume calculated according to the shape, size and quantity of the gas collecting hood in the workshop and the control wind speed. If it fails to meet the requirements, it shall be modified by replacing a high-power fan, adding a flue fan, adding a vertical curtain, etc.

 

02 Equipment quality
The internal structure of horizontal activated carbon canister and box type activated carbon canister shall be reasonably designed, with smooth gas flow, no short circuit and no dead angle. The doors, welds and pipe connections of the activated carbon adsorption device shall be tight without air leakage. All bolts and nuts shall be surface treated and firmly connected. The shell of metal device shall be made of stainless steel or anti-corrosion treatment, and the surface shall be smooth and clean without rust, burr, uneven concave and convex defects.
The exhaust fan should be installed at the rear end of the adsorption device to form a negative pressure, so as to ensure that no polluting gas leaks outside the tank body of the equipment box.
Sampling ports shall be set on the inlet and outlet pipes of the activated carbon adsorption device, which shall meet the requirements of Technical Requirements for Environmental Protection Products - Industrial Waste Gas Adsorption and Purification Device HJ/T 386-2007, so as to facilitate daily monitoring of the activated carbon adsorption efficiency. The activated carbon shall be replaced timely according to the replacement cycle of activated carbon, and the replaced activated carbon shall be treated as hazardous waste.  

 

03 Gas flow rate
The gas flow rate of the adsorption layer of the adsorption device shall be determined according to the form of the adsorbent. When granular activated carbon is used, the gas flow rate should be less than 0.60m/s, and the filling thickness should not be less than 0.4m. The activated carbon shall be completely filled to avoid short circuit of air flow; When activated carbon fiber is used, the gas flow rate should be lower than 0.15m/s; When honeycomb activated carbon is used, the gas flow rate should be lower than 1.20m/s.

 

04 Waste gas pretreatment
The content and temperature of waste gas particles entering the adsorption equipment shall be lower than 1mg/m respectively ³ And 40 ℃, if the particle content exceeds 1mg/m ³ Filter or wash shall be used for pretreatment.
The adsorption effect of activated carbon on acid waste gas is poor, and acid gas is easy to cause corrosion to the equipment body, so washing shall be used for pretreatment first.
The enterprise shall formulate equipment operation and maintenance procedures for regular replacement of filter materials to ensure the use of activated carbon under the conditions of low particulate matter and low moisture content.

 

05 Quality of activated carbon
Iodine adsorption value of granular activated carbon ≥ 800mg/g, specific surface area ≥ 850 ㎡/g;
The horizontal compressive strength of honeycomb activated carbon shall not be less than 0.9MPa, the longitudinal strength shall not be less than 0.4MPa, the iodine adsorption value shall be ≥ 650mg/g, and the specific surface area shall be ≥ 750m2/g. The specific surface area of activated carbon fiber shall not be less than 1100 ㎡/g (BET method);
The enterprise shall prepare the product quality certification materials about the iodine value, specific surface area and other products of the purchased activated carbon manufacturers for future reference.

 

06 Filling amount of activated carbon
Disposable granular activated carbon is used to treat VOCs waste gas. Generally, the annual amount of activated carbon used should not be less than 5 times the amount of VOCs produced, that is, 1 ton of VOCs produced, and 5 tons of activated carbon are needed for adsorption. Generally, the replacement cycle of activated carbon shall not exceed 500 hours or 3 months of accumulated operation. In actual work, the filling amount and replacement cycle shall be determined according to the actual situation of the enterprise.

 

07 Standardize enterprise environmental protection management
The activated carbon adsorption treatment unit shall be started before the production process equipment generating waste gas and shut down later than the production process equipment, and the interlocking control with the production unit is encouraged if conditions permit. The activated carbon adsorption device shall be provided with a nameplate and posted at a conspicuous position of the device (refer to the setting specification of drain outlet), including the name, model, air volume, name of activated carbon, filling amount, filling method, iodine value of activated carbon, specific surface area, etc. of environmental protection products. The enterprise shall keep daily operation and maintenance account records of activated carbon adsorption, mainly including equipment operation start and stop time, equipment operation parameters, consumption of consumables (purchase amount, usage amount, filling amount, replacement amount and replacement time, disposal records, etc.) and energy consumption (power consumption).
In actual work, the safety production requirements should be strictly implemented and the activated carbon treatment process should be standardized.
Enterprises that have not built supporting waste gas treatment facilities shall be ordered to stop production according to law and rectify within a time limit; In addition to odor control, new enterprises shall not adopt single low temperature plasma, photocatalysis, photo oxidation, water spray and other low efficiency end treatment technologies. Existing enterprises shall be replaced with efficient treatment processes (such as combustion technology) as soon as possible or modified with multiple process combinations.

 

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