The Quzhou Ecological Environment Bureau issued a letter to enterprises in the city that use activated carbon to treat VOCs waste gas, in order to scientifically guide enterprises to use activated carbon in a standardized manner and ensure that pollutants are stably discharged in compliance with standards.
A letter to enterprises in the city that use activated carbon to treat VOCs waste gas
Hello!
In recent years, ozone (O3) has become the primary pollutant that causes the air quality in our city to exceed the standard, affecting the production and life of the people. Volatile organic compounds (VOCs) are one of the important precursors of ozone formation, and reducing VOCs emissions can effectively control ozone pollution.
Environmental engineering practice shows that adsorption is the most mature and common method for VOCs treatment on the market (suitable for enterprises with small VOCs emissions), and the most common adsorbent is activated carbon, which is often used in large air volume and low concentration VOCs treatment, and plays an irreplaceable and important role in VOCs waste gas treatment. However, in the daily supervision of the ecological environment department, it was found that many enterprises had problems such as long-term failure to replace activated carbon or failure to open the facilities normally, the activated carbon used was damp or seriously damaged, and the use of inferior carbon during the use of activated carbon facilities, resulting in some adsorption devices being unable to play their due role, and some were even useless.
Recently, our city has experienced continuous rainfall, and activated carbon is very susceptible to moisture, which affects the collection and treatment of waste gas. In order to scientifically guide enterprises to use activated carbon in a standardized manner and ensure that pollutants are stably discharged in compliance with standards. Our bureau now popularizes science and advocates the following:
1. Standardized use of activated carbon
1. Select high-quality activated carbon
Enterprises should choose granular activated carbon as an adsorbent, and the iodine value of granular activated carbon (an important indicator for measuring the adsorption capacity of activated carbon) should not be lower than 800mg/g, and the carbon tetrachloride adsorption rate should be ≥60%. Enterprises should prepare the product quality certification materials of the activated carbon manufacturer for the iodine value, specific surface area, carbon tetrachloride adsorption rate, etc. for reference. At the same time, the advantages and disadvantages of activated carbon can be identified through the simple method of "one look, two weigh, three test, four test".
2. Use compliant adsorption devices Use adsorption devices that comply with the requirements of the "Technical Specifications for Industrial Organic Waste Gas Treatment Engineering by Adsorption Method" (HJ 2026-2013). A filter device is required before the activated carbon. For paint spraying exhaust with more paint mist, a dry paint mist capture and filtration system should be used. The concentration of exhaust particulate matter or oil smoke should not exceed 1mg/m3. A differential pressure gauge is installed in front of the filter of the activated carbon box. When the resistance is lower than the initial value or reaches 1.5~2 times the initial resistance value, it should be checked and replaced in time. Do a good job of outdoor sun protection. The inlet exhaust gas temperature should not exceed 40℃ (preferably below 35℃), and the relative humidity should not exceed 80%. The activated carbon box should adopt a multi-layer air distribution structure and be equipped with an activated carbon loading and unloading hole/door. The apparent flow rate of the carbon layer using granular activated carbon should be controlled at 0.4~0.6m/s, the single-layer thickness of the carbon layer should be controlled at 400~450mm, and the residence time of the exhaust gas in the carbon layer is generally not less than 0.75s. When the concentration of imported VOCs in organic polymer processing, deodorization or other production processes is very low, the relevant parameter requirements can be appropriately lowered. For reference on activated carbon loading, see the attached table.
Note: 1. The minimum loading amount of activated carbon with air volume exceeding 20000Nm3/h can be estimated by referring to this table; 2. If characterized by NMHC index, the VOCs concentration: NMHC concentration ratio can be estimated by referring to 2:1.
3. Regular replacement of activated carbon Enterprises should determine the activated carbon replacement cycle according to the design plan of waste gas activated carbon adsorption treatment facilities. In principle, the activated carbon replacement cycle should generally not exceed 500 cumulative hours or 3 months of operation; when there is no waste gas treatment facility design plan or the actual construction situation does not conform to the design plan, refer to the following formula to calculate the activated carbon replacement cycle:
Note: If the dynamic adsorption value in the calculation is higher than 15%, the activated carbon performance certification document containing the basis for the dynamic adsorption value should be provided.
4. Standardized disposal of waste activated carbon. The replaced waste activated carbon is hazardous waste, so it should be stored in a closed manner and handed over to enterprises with hazardous waste disposal qualifications for regeneration or disposal in accordance with the law. Keep relevant records in accordance with HJ 944 and other specifications. The record retention period shall not be less than 5 years. 5. Regularly maintain the adsorption device. Establish an operation and maintenance record of the waste gas treatment facility to record the operation and maintenance of the facility and the replacement of consumables, such as the replacement time and replacement amount of activated carbon; regularly check whether the waste gas collection pipeline and adsorption equipment are damaged, whether the filter material needs to be replaced, etc.
2. Pay attention to the following illegal acts
1. Substituting inferior activated carbon for good ones, purchasing and using low-iodine activated carbon; insufficient activated carbon filling, non-standard filling, long-term non-replacement, etc.
According to Article 108 of the "Law of the People's Republic of China on the Prevention and Control of Air Pollution", if the production and service activities that produce volatile organic waste gas fail to install and use pollution prevention and control facilities in accordance with the regulations, the ecological environment department of the people's government at or above the county level shall order rectification and impose a fine of not less than 20,000 yuan but not more than 200,000 yuan; if rectification is refused, it shall be ordered to suspend production for rectification.
2. Activated carbon treatment facilities are not opened normally, activated carbon is not filled in the activated carbon box, etc.
According to Article 99 (iii) of the "Law of the People's Republic of China on the Prevention and Control of Air Pollution", if air pollutants are discharged by evading supervision, the ecological environment department of the people's government at or above the county level shall order rectification or restrict production, suspend production for rectification, and impose a fine of not less than 100,000 yuan but not more than 1 million yuan; if the circumstances are serious, the people's government with approval authority shall approve the suspension of business or closure.
3. Failure to establish a ledger in accordance with regulations to record the main operation and maintenance information of the treatment facilities, such as the activated carbon replacement cycle and replacement amount, etc.
According to Article 69 of the Regulations on Pollutant Discharge Permit Management, if the ledger is not recorded in accordance with the requirements of the pollutant discharge permit or the content of the ledger is untrue or incomplete, the local ecological and environmental authorities at or above the prefecture-level city shall order rectification and impose a fine of not less than RMB 1,000 and not more than RMB 20,000 per day (calculated on a daily basis); if rectification is refused, the administrative authority that makes the penalty decision in accordance with the law may impose continuous daily penalties according to the original penalty amount from the day after the date of the order to rectify.
4. Excessive emission of volatile organic compounds (VOCs)
According to Article 99 (II) of the Law of the People's Republic of China on the Prevention and Control of Air Pollution, if the emission of air pollutants exceeds the air pollutant emission standards or exceeds the total emission control indicators of key air pollutants, the ecological and environmental authorities of the people's governments at or above the county level shall order rectification or restrict production, suspend production for rectification, and impose a fine of not less than RMB 100,000 and not more than RMB 1 million; if the circumstances are serious, the people's government with approval authority shall approve the suspension of business or closure.
5. Initiative
Entities that use activated carbon to treat VOCs waste gas in the city are requested to use activated carbon in a standardized manner, especially in recent rainy days with high air humidity. Activated carbon is very susceptible to moisture and failure, resulting in excessive waste gas emissions. We must attach great importance to it, and replace activated carbon and adsorption devices with poor treatment capacity through self-inspection of activated carbon use to ensure that waste gas is discharged normally and meets the standards.
In the next step, our bureau will combine routine inspections with the 2023 "Blue Sky" special law enforcement inspection action on the atmospheric environment, and carry out special inspections focusing on the replacement of activated carbon and the use of treatment facilities in adsorption process enterprises. Once environmental violations are found, they will be investigated and dealt with in accordance with laws and regulations.
