Leather processing

The main sources of exhaust gas in the production of synthetic leather are the volatilization of organic solvents:

(1) Volatilization of resin and solvent during batching, transportation and storage;

(2) Volatilization of organic matter during processing such as coating or impregnation;

(3) volatilization of organic matter during heating in the oven;

(4) volatilization of organic matter in the post-treatment process.

Exhaust pollutants are related to the specific process and formulation composition. For a certain process, the formula can often be changed, so the specific pollutants produced are not fixed. The general pollutants in the production process are

①Dry polyurethane process: organic solvents (DMF, toluene, xylene, butanone, etc.)

②Wet polyurethane process: organic solvents (DMF)

③ Polyvinyl chloride and other related processes: plasticizer fumes (dioctyl phthalate, etc.), vinyl chloride, hydrogen chloride, organic solvents, lead

④Post-treatment process: organic solvents (DMF, toluene, xylene, butanone, butyl acetate, etc.), particulate matter

⑤ Microfiber process: organic solvents (DMF, toluene, xylene, etc.)

Exhaust emission standards, with reference to the "Volatile Organic Compounds Control Emission Standards" (GB37822-2019), "Shandong Province Volatile Organic Compounds Emission Standards" (DB37-2801), the following table of exhaust emission standards:

(1) information provided by the owner in relation to the project

(2) "Law of the People's Republic of China on Environmental Protection" (2015-01-01)

(3) "Air Pollution Prevention and Control Law of the People's Republic of China" (2016-01-01)

(4) Ambient Air Quality Standards (GB3095-2012)

(5) "Law of the People's Republic of China on the Promotion of Cleaner Production", Decree No. 72 of the President of the People's Republic of China

(6) National Environmental Protection "Thirteenth Five-Year" Plan

(7) "Comprehensive Emission Standards for Air Pollutants" (GB16297-1996)

(8) "Emission Standards for Odor Pollutants" (GB14554-1993)

(9) "Environmental Protection Design Code for Construction Projects" (GB50483-2009)

(10) "Design Code for Heating, Ventilation and Air Conditioning" (GB50019-2003)

(11) "Building Design Fire Code" (GB50016-2014)

(12) "Code for the design of power supply and distribution systems" (GB50052-2009)

(13) "Emission Standards for Volatile Organic Compounds Control in Industrial Enterprises" DB13/2322-2016

>>Exhaust gas system design

The proposed process route adopts "catalytic combustion + activated carbon adsorption and desorption + fan" for effective exhaust gas treatment. The process equipment diagram is as follows:

催化燃烧+活性炭吸附脱附+风机

(1) After the waste gas is pretreated to remove dust and particulate matter, it is sent to the activated carbon adsorber. When the activated carbon adsorber Ⅰ is close to saturation, firstly, the treated gas is automatically switched to the activated carbon adsorber Ⅱ (activated carbon adsorber Ⅰ stops adsorption operation), and then the hot airflow is used to desorb and desorb the activated carbon adsorber Ⅰ to desorb the organic matter from the activated carbon. In the desorption process, the organic waste gas has been concentrated, the concentration is tens of times higher than the original, up to 2000ppm or more, the concentrated waste gas is sent to the catalytic decomposition device, and finally it is discharged as CO2 and H2O.

(2) After completing desorption and desorption, the activated carbon adsorber Ⅰ enters the standby state, and when the activated carbon adsorber Ⅱ is close to saturation, the system automatically switches back and desorbs and desorbs the activated carbon adsorber Ⅱ at the same time, so the cycle works.

(3) When the concentration of organic waste gas reaches 2000ppm or more, the catalytic bed can be maintained in self-ignition without external heating. This solution not only saves the energy consumption greatly, but also reduces the equipment investment because the processing capacity of catalytic decomposer is only 1/10 of the original exhaust gas processing capacity. This solution is suitable for both continuous and intermittent operation.

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