Main role of air filter in radioactive waste gas treatment
The radioactive exhaust gas of the air filter belongs to the gas that is relatively harmful to the human body, Air filter is very important for its treatment method. Therefore, air filter is generally used for treatment in the industry. The main functions of various air filters will be described below. Air filter radioactive waste gas purification technology: there are many methods for waste gas purification, including filtration, adsorption, washing, retention and decay. Common exhaust gas purification equipment includes: filtration: air inlet prefilter (used to remove the dust from the air inlet, with a filtering efficiency of at least 85%); air exhaust prefilter (installed before the high-efficiency air particle filter, to remove the coarse particles in the air flow and improve the service life of the high-efficiency particle air filter, with a filtering efficiency of at least 85%); and high-efficiency filter (used to collect the fine particles in the air flow, with a filtering efficiency of at least 95%) High efficiency particulate air filter (absolute filter HEPA is used to collect ultra-fine particles and dust in exhaust gas, and the particle size is less than 0.3 μ M U.M particles, removal efficiency > 99.97%)) iodine filter (iodine adsorber usually uses 1% ki impregnated activated carbon as the medium, the removal rate of elemental iodine can reach 99.9%, and the removal rate of organic iodine can reach 99%)) other types of filters (bag filter, metal sintered filter, ceramic candle filter, ruthenium filter). According to the characteristics of waste gas, select appropriate process technology for purification treatment, and discharge to the atmosphere is allowed after reaching the standard. The secondary wastes (such as waste filter core, waste activated carbon, waste filter bag, etc.) generated in the exhaust gas purification process should be reasonable and as little as possible. The exhaust gas purification system shall prevent leakage. The exhaust gas purification system may have the accumulation of soot and oil, and the occurrence of combustion and explosion accidents shall be prevented. The retention decay storage system shall have sufficient retention decay time and sufficient storage capacity (the decay storage tanks are standby for each other). The air filter shall be inspected regularly and replaced timely to ensure that the filtering efficiency is met. When the radiation field intensity is high, the filter shall be replaced remotely. Low wind speed makes the air filter better: As we all know, the filtering effect of air filter has a certain relationship with the wind speed. Most people may think that the higher the wind speed, the better the filtering effect of air filter. However, the reality is just the opposite. The smaller the wind speed, the better the effect of "Zijing" brand air filter. See the detailed analysis below for details The diffusion effect of small particle size dust (Brownian motion) is obvious. When the wind speed is low, the air flow will stay in the filtering data for a longer time, and the dust will have more opportunities to impact the obstacles, so the filtering efficiency is high. Experience shows that as for the high-efficiency filter, if the wind speed is reduced by half, the dust transmission rate will be reduced by nearly an order of magnitude (the efficiency value will be increased by 9); if the wind speed is doubled, the transmission rate will be increased by an order of magnitude (the efficiency will be decreased by 9). Similar to the effect of diffusion, when the filter material is static (electret data), the longer the dust stays in the filter material, the greater the possibility of being absorbed by the data. If the wind speed is changed, the filtering efficiency of electrostatic data will be significantly changed. If you know that there is static electricity on the data, you should reduce the air volume passing through each filter as much as possible when you stop the design of the air conditioning system. As for the large particle dust mainly based on inertial mechanism, according to the traditional theory, the probability of collision between dust and fiber will be reduced and the filtration efficiency will be reduced when the wind speed is reduced. However, in theory, this effect is not obvious. As the wind speed is small, the fiber's resilience to the dust is also small, and the dust is more likely to be stuck. When the wind speed is high, the resistance is large. If the service life of the filter is based on the final resistance and the wind speed is high, the service life of the filter is short. It is difficult for ordinary users to observe the effect of wind speed on filtration efficiency, but it is much easier to observe the effect of wind speed on resistance. As for the high-efficiency filter, the speed of air flow through the filter material is generally 0.01-0.04m/s. Within this range, the resistance of the air filter is in direct proportion to the filtered air volume. For example, a 484 × four hundred and eighty-four × The initial resistance of 220mm "Zijing" brand high-efficiency filter is 250pa under the rated air volume of 1000m3 / h. If the actual air volume in operation is 500m3 / h, its initial resistance can be reduced to 125pa. For the common ventilation filter in the air-conditioning box, the speed of air flow through the filter material is within the range of 0.13-1.0m/s. The resistance and air volume are no longer linear, but an upward arc. The air volume increases by 30%, and the resistance may increase by 50%. If the filter resistance is a very important parameter for you, you need to ask the filter supplier for the resistance curve.