The fish meal plant turns leftover aquatic goods, along with some tiny fish and shrimp, into fish meal for feed using a variety of techniques, including high-temperature steam heating, pressing, drying, and crushing. Malodorous gas is created at numerous points in the production process, and the odor seriously pollutes the air.
1.Source of odourous gas
The processing technology of fish meal in my country is generally: aquatic product scraps, wet drying, pulverization, dryer drying, and making fish meal.
The primary odor-causing factors are:
1) Organized emission sources, such as high-temperature cooking exhaust gases from fish mael wet drying furnaces;
2) Unorganized emission sources, such as raw material storage yards, wastewater, wastewater treatment facilities, raw material transfers in manufacturing, etc. The main sources of odor among them are high-temperature cooking, raw material storage areas, and raw material transfers.
2.Process route selection
There are many purification methods for malodorous gas, mainly including the following:
1) Masking method (neutralization method, odor elimination method): The malodorous gas is mixed into the scented mixture to mask the odor.
2) Air oxidation (combustion) method: use most odorous substances with reducing characteristics, such as organic sulfur and organic amines, to carry out oxidative deodorization. There are thermal oxidation and catalytic combustion.
3) Water spraying method: Dissolving malodorous gas with water to remove malodorous odors.
4) Chemical oxidation absorption method: Borrowing the chemical unit operation theory, it is suitable for treating waste gas with high concentration of malodorous pollutants, with mature technology, stable operation and small footprint , the processing efficiency is higher.
5) Adsorption method: The odorous substances are adsorbed by adsorbent activated carbon, activated clay, etc., with high deodorization efficiency and low power consumption.
6) Photocatalytic oxidation method: Under the irradiation of high-energy ultraviolet light, various reactions (photochemical reactions) such as ring opening and breaking of chemical bonds of volatile organic compounds (VOCs) are degraded into low molecular compounds such as CO2 and H2O; on the one hand, high-energy ultraviolet light is used. Oxygen in the air is irradiated by light to generate ozone, ozone absorbs ultraviolet rays to generate oxygen free radicals and oxygen, and oxygen free radicals react with water vapor in the air to generate hydroxyl free radicals, a stronger oxidant, and organic The exhaust gas is completely oxidized to inorganic substances such as water and carbon dioxide. In addition, ozone that does not absorb ultraviolet rays is also a strong oxidant, and after contacting with some organic wastes, it oxidizes to form inorganic substances such as water and carbon dioxide.
7) Combined method: When the deodorization requirements are high and it is difficult to meet the requirements with a single purification process, the combined deodorization method is used, that is, several methods are used in combination to improve the deodorization efficiency and reduce operating costs.
Selected photocatalytic deodorization process. The fish meal exhaust gas is drawn out through the induced draft fan, and enters the dust removal, cooling and dehumidification equipment through the dust hood pipe for pretreatment, and then enters the photocatalytic deodorization equipment. After treatment, it can reach qualified discharge.
After spraying a large amount of cooling water, most of the organized high-temperature steam from Fanxiang equipment is condensed and sent to the deodorization tower, and the mixed dust in the steam is also washed. It is then transferred to a dehumidifying filter for drying under the suction of the blower. Finally, the steam is diverted to an ion photocatalytic purifier, where ion and UV light tubes are used to break down odor molecules, bringing the steam up to emission standards.
Post time: Nov-10-2022