The malodorous gas produced by experimental animals mainly comes from the malodorous gas produced during the animal feeding and experimental stages. According to the analysis of the odor components, the exhaust gas produced by the experimental animals is mainly composed of ammonia and sulfide.
It can burn the skin, eyes, and mucous membranes of respiratory organs. If people inhale too much, it can cause lung swelling and even death.
An acute poison, inhaling a small amount of high-concentration hydrogen sulfide can be fatal in a short time. Low concentrations of hydrogen sulfide have effects on the eyes, respiratory system and central nervous system; such as methyl mercaptan, its toxic effect is similar to hydrogen sulfide. Inhalation of methyl mercaptan vapor can cause headache, nausea and varying degrees of anesthesia; high concentration of vapor can cause respiratory paralysis and death. This product has a strong stimulating effect on eyes, skin, mucous membrane and upper respiratory tract. May cause damage to liver and kidney. Methyl sulfide vapor is irritating to the nose and throat, causing cough and chest discomfort. Sustained or high concentration inhalation headache, nausea and vomiting. Liquid or mist is irritating to eyes. May cause dermatitis.
To sum up, the concentration of exhaust gas produced by experimental animals is relatively high, and the exhaust gas is discharged directly without effective treatment, which will cause a great degree of pollution to the surrounding environment, especially the social impact is extremely bad. Therefore, it is necessary to use the collection pipeline to collect the exhaust gas in a centralized manner, and then pass it through the purification system to meet the standard and then discharge it at high altitude.
Exhaust Approach
The principle of secondary treatment of the general exhaust pipe after partial primary treatment should be adopted.
At present, the main methods used for exhausting ammonia and hydrogen sulfide include local chemical treatment, absorption pollution and odor treatment, and photolysis treatment. The specific handling principles are as follows:
➤ Local chemical treatment: At present, there are mainly chemical filters for ammonia and hydrogen sulfide; the branch pipe of the exhaust system should be equipped with chemical devices to eliminate pollution, such as chemical filters, and should be set in the negative pressure section of the fan. The equipment space should be reserved according to the amount of pollution and odor treatment, and the operation space for the valves, motors, detection holes, etc. of the relevant equipment should be reserved at the same time. Sufficient space for installation and maintenance should be left between the main equipment of the pollution and odor treatment system, and the surrounding area of the main equipment should meet the requirements of emergency passages and specifications.
➤Absorption pollution and odor treatment: The factors that should be considered in the selection of absorption process are mainly pollution odor properties, flow rate, concentration, absorbent properties, absorption device characteristics and economical efficiency, etc. Absorption devices include spray towers, plate towers, turbulent ball towers, etc. Activated carbon adsorption can be used in emergency conditions.
➤Photolysis treatment: Factors to be considered in the selection of photolysis process: flow rate, flow rate, pressure, composition, nature, inlet concentration, discharge concentration, etc. of polluted gas. It should be designed according to 120% of the maximum polluting odor emission, and the airflow speed should be controlled. The continuous working time of photolysis equipment should not be less than 12 months. The contact time of the gas should be ≧1.0s.
➤Jet exhaust method: also known as exhaust jet cylinder method. The height of the exhaust pipe should meet the requirements of the current national air pollutant discharge standards, and the minimum height should not be less than 15m. The height of the exhaust pipe refers to the vertical height from the ground to the exhaust outlet. The wind speed at the outlet of the exhaust pipe should be ≧15.5m/s, and the exhaust capacity should be reserved for centralized large-scale exhaust pipes. The exhaust stack shall be provided with sampling holes and monitoring platforms for monitoring, as well as necessary auxiliary facilities. The top of the exhaust jet tube should not be provided with an umbrella cap.
