The purpose of VOCs (volatile organic compounds) assessment and monitoring is to understand the VOCs concentration level, distribution and **, to help enterprises grasp VOCs emissions and better control pollution sources. At present, there are several problems in the monitoring of VOCs:
1. The collection of ledgers is incomplete
In terms of VOCs material ledger, enterprises generally do not summarize all the information that needs to be sorted out on a ledger as required, and the record format is not standardized; In terms of the operation ledger of treatment facilities, enterprises lack systematic information records, especially incomplete information records such as operation time, waste gas treatment capacity and residence time.
2. The efficiency of exhaust gas collection is low
In the process of on-site inspection, on the one hand, it is difficult to seal the production workshop due to the large production workshop or the excessive movement of production equipment, the production line is too long, etc.; On the other hand, some enterprises collect the organic waste gas generated in the molten state of plastic by setting up a local gas collection hood in the workshop, because the distance between the gas collection hood mouth and the control point is far, resulting in poor collection effect, so that the monitoring data is not biased.
3. The removal rate of treatment facilities is low
On the one hand, for enterprises with an annual output of less than 10 tons, the process is mainly spray or dry filter cotton + UV photolysis + activated carbon, in the process of on-site inspection, it is found that the number of UV lamps installed by some enterprises does not match the processing capacity, or the particles generated by the process do not go through pretreatment directly into the UV photolysis device, and the particles settle on the UV lamp, and the photolysis effect is minimal.
On the other hand, the amount of activated carbon filling does not match the amount of volatile organic compounds to be treated, or because the activated carbon is not replaced for a long time, the activated carbon is in a state of failure, or the flow rate of the exhaust gas in the adsorption device is too fast and the residence time is insufficient, resulting in the volatile organic compounds in the exhaust gas being discharged without being adsorbed or not achieving the desired treatment effect.
4. The disposal of hazardous waste is not standardized
The enterprise did not put secondary pollutants such as spray waste liquid, adsorption saturated waste activated carbon, filter cotton or outer packaging contaminated with organic solvents into the designated hazardous waste storage site, or did not seal and store it in time after disposal, which is easy to cause fugitive emission of volatile organic compounds.
5. The setting of the sampling port or sampling port is not standardized
In order to calculate the removal rate of treatment facilities, enterprises should set up permanent standard sampling ports at the appropriate positions of the air ducts before and after the exhaust gas treatment facilities, and the location of the sampling ports should be set at not less than 6 times the diameter from the downstream direction of the elbow, valve and reducer and not less than 3 times the diameter from the upstream direction of the above components.
Enterprises should improve the accuracy and reliability of VOCs inspection results by establishing a comprehensive ledger, improving the efficiency of waste gas collection and the removal rate of treatment facilities, standardizing the treatment of waste, and standardizing the selection of sampling points and sampling equipment, so as to provide data support and scientific basis for pollution source control, policy formulation and environmental management, and help enterprises achieve ultra-low emission goals.