Views: 3 Author: Xicheng EP LTD Publish Time: 2022-09-28 Origin: Xicheng EP LTD
The main components of waste gas treatment in the sewage station are anaerobic reaction to produce H2S, nitrogen, mercaptan, and sulfide gas, which leads to the generation of peculiar smell. It is necessary to collect and treat the odor of sewage treatment by blocking to solve the problem of the odor of sewage treatment station. Impact. The following is an example of a sewage station deodorization project to explain the solution for odor elimination in sewage stations.
The main processes that produce odor in the sewage station in this design plan include primary sedimentation tank, secondary sedimentation tank, air flotation tank, A tank, SBR tank, and sludge thickening tank. Collect and process the collected gas in a centralized manner, cooperate with the corresponding design and supporting equipment foundation production, equipment installation, electrical installation, system operation and debugging.
Introduction of sewage deodorization process
According to the situation on site, the exhaust gas is high-humidity gas with high temperature, and the exhaust gas is mainly ammonia, hydrogen sulfide, methyl sulfide, methyl mercaptan, odor and other gases. There are mainly the following treatment methods for this kind of waste gas:
The facilities for washing and treating odor should include washing tower, washing liquid circulation system, dosing system, electrical control system, demisting device, etc. The washing method should set up washing stages such as water washing, acid washing, alkali washing, and oxidation according to the composition, concentration and emission standards of the malodorous gas, and select water or detergents containing acid and alkali, chemical oxidants and co-solvents, etc., and should meet the following requirements :
Large capacity and high selectivity;
Low saturated vapor pressure, high boiling point and good thermal stability;
Not easy to foam, low viscosity;
Good chemical stability, low corrosiveness, non-toxic, cheap and easy to obtain;
The rich liquor produced by washing is easy to be comprehensively processed.
Activated carbon adsorption is suitable for deodorization treatment with low intake air concentration. The activated carbon adsorption deodorization system shall meet the following requirements:
The particulate matter in the odor should be removed;
The number of regenerations and replacement cycles of activated carbon should be determined according to factors such as odor emission requirements and activated carbon adsorption capacity;
The temperature of odor should not be higher than 80 ℃;
When the odor and humidity are too high, dehumidification measures should be added;
The activated carbon material should be granular activated carbon, the particle size should be 3~4mm, the porosity should be 0.5-0.65, and the specific surface area should not be less than 900 m2/g;
The filling density of the activated carbon layer should be 350-550 kg/m3;
Activated carbon can be arranged in layers and in parallel.
According to the site inspection and communication with the owner, the waste gas mainly comes from the high-humidity and high-temperature gas generated during the treatment of industrial wastewater. The gas has a high water content, and hot gas can be clearly felt at the site, mainly steam containing pollutants. , In view of this phenomenon and exhaust gas detection data, our company mainly adopts three-stage chemical washing method, namely acid chemical washing + oxidative chemical washing + alkaline chemical washing, so that the pollutant discharge can meet the relevant emission standards in the "Odor Pollutant Emission Standard".
According to the analysis of waste gas components, it is mainly acidic, alkaline and organic waste gas, and the gas concentration is not high, but the gas is malodorous gas, and people can clearly feel the stench. Because hydrogen sulfide is acidic, it is easy to neutralize with sodium hydroxide solution. In engineering, sodium hydroxide solution is a relatively cost-effective absorption liquid, with a treatment efficiency of more than 95%. Ammonia gas is a common malodorous gas. Ammonia gas is very easy to dissolve in water, and the aqueous solution is weakly alkaline. It has high mass transfer efficiency and fast reaction speed in contact with acidic absorption liquid, and the treatment efficiency of ammonia gas is above 99%. Because the gas contains more methyl mercaptan and methyl sulfide organic gases, the absorption efficiency of ordinary acids and bases is low. For such gases, our company has found that when such gases are in a medium with strong oxidizing properties The removal efficiency is high. Combined with a large number of experiments, special agents for this type of organic waste gas have been developed and applied to the spray tower, and the effect is remarkable.
Due to the detection of methane gas in the exhaust gas, the concentration is higher than the explosion limit of flammable and explosive gas required by plasma equipment, so plasma and UV photolysis equipment is not recommended.
The Wet Scrubber can effectively remove the acid/alkaline gas contained in the waste gas, and the waste gas treatment equipment is produced with PP as the main material. The packing is made of PP Raschig rings. According to the principle that the gas-liquid two-phase conducts mass transfer reaction on the surface during the gas absorption process and the transfer rate is proportional to the specific surface area, the filler is used to increase the specific surface area of the two-phase contact, so that the two phases are fully contacted, so as to achieve absorption and The purpose of purifying exhaust gas. The moisture content of the purified gas is relatively large, so that the gas passes through the defogging layer, and the defogging layer packing can effectively absorb the moisture in the gas, and the purified gas is discharged from the air outlet.
The working principle of the Wet Scrubber: the structural type of the washing tower is divided into vertical and horizontal.
The working principle of the vertical Wet Scrubber is gas-liquid two-phase countercurrent contact; the waste gas containing sulfur dioxide enters the tower from the lower inlet of the tower and moves upwards, through single-layer or multi-layer packing, the waste (tail) gas is fully contacted with the liquid phase and then absorbed or absorbed. Neutralized, clean gas is discharged through the upper demister layer, so as to achieve the effect of absorption and purification.
The working principle of the horizontal Wet Scrubber structure is gas-liquid two-phase cross-flow contact. When the waste (tail) gas passes through the packing layer, it is fully contacted with the liquid phase and then absorbed or neutralized, so as to achieve the effect of absorption or purification.
The equipment itself includes the washing tower body, the packing layer, the defogging layer, the circulating water pipeline, and the circulating water tank.