pm2. 5衡量标准

mmsy5201314 2017-09-16 01:58:13 547 浏览

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socool薇 2017-09-16 12:57:40

pm2. 5，即细颗粒物的标准，是由美国在1997年提出的，主要是为了更有效地监测随着工业化日益发达而出现的、在旧标准中被忽略的对人体有害的细小颗粒物。细颗粒物指数已经成为一个重要的测控空气污染程度的指数。目前，我国的pm2.5标准值为24小时平均浓度小于75微克/立方米为达标，然而，这一数值与pm2.5国际标准相比，还相差甚远，仅仅是达到世卫组织设定的Z宽标准。世界卫生组织(WHO)认为，pm2.5标准值为小于每立方米10微克。年均浓度达到每立方米35微克时，人患病并致死的几率将大大增加。而以世卫组织数据为准的话，pm2.5国际标准分别为准则值，24小时小于25微克;过渡期目标1，24小时小于75微克;过度目标2，24小时小于50微克;过度其目标3，24小时小于37.5微克。

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高分英译中 (5): CIPTankFill–theCIPtankisfilledfromoneoftheunitsinoperation.CIPTankHeating–foracidCIPs，thewaterintheCIPtankisheatedto40°C.Backwash-Theskidisbackwashedtoremoveexcesssoli... CIP Tank Fill – the CIP tank is filled from one of the units in operation. CIP Tank Heating – for acid CIPs， the water in the CIP tank is heated to 40 °C. Backwash - The skid is backwashed to remove excess solids and maximize the chemical cleaning efficiency. The backwash waste is drained to the regular waste outlet. Hot water Fill - The skid is filled with water from the CIP tank. Filtrate Recirculation and Chemical Dosing - The CIP transfer/recirculation pump starts to recirculate the water to the skid in a closed loop. The skid is fully isolated from the rest of the system， typically by block and bleed systems. The acid or chlorine (sodium hypochlorite) is added in the loop at the beginning of the recirculation sequence until the appropriate quantity of cleaning chemical is added. Filtrate Recirculation – The cleaning solution is recirculated through the filtrate side of the membrane array. This step is similar to filtration. Soak/Aeration - The modules are left to soak for a preset time. With an acid clean， repeated aeration steps can be used to improve cleaning efficiency. Draindown - The cleaning solution is drained away from the skid to drain or to the neutralization system if the system incorporates one. Rinse Backwash - The skid is refilled with feed water and backwashed to remove residual chemical. All rinse water is directed to drain or the neutralization system. Filtration to Waste – The unit is put into filtration but the filtrate with chemical residue is sent to drain or the neutralization system. The pH and ORP meters are used to verify that the skids have been rinsed to the point where the filtrate has no chemical cleaning residue. The unit can then be put back into filtration or standby. Pressure Decay Test (PDT) The integrity test procedure is similar to that used on all of the other Memcor systems. The principal process steps include draining down the lumen of the fibers， pressurizing the inside of the module fibers with integrity air while the upper backwash waste outlet valve is open to atmospheric pressure， shutting down the air supply and monitoring the pressure over time using the filtrate pressure transmitter supplied with each unit. The PDT result is logged on the SCADA system and displayed on the SCADA computer as well as the optional local HMI. This result is used to calculate the Log Removal Value (LRV)， which confirms integrity of the system. Each Memcor CP unit is tested at regular time interval adjustable by the operator. The time interval is set at 24 hours by default. 展开