Humidification of dusty materials
The chemical industry, along with ventilation and aspiration is widely used wetting dusty materials and gidroobespylivanie. This particularly applies to the processing of materials that emit toxic dust.
However gidroobespylivanie, and the more moisture is not always possible. On some production materials may be processed only in the dry state. These industries include, for example, the production of lime, cement, glass, colored pigments, etc. In such cases, of particular importance and sealing kapsyulyatsiya dusting apparatus. Keep in mind that fine dust can pass through even the smallest leaks, for example through the seals. If this dust is poisonous, contains, say, mercury, lead, cadmium or chromium salts, it can not tolerate even the slightest breaches of the premises. In this case, perhaps, the only acceptable solution is to cover dusting devices in the cabin.
dusty processes associated with manual work - packing, rastarivanie n, etc. - certainly should be in shelters with air suction. Sometimes, for example in packaging bulk mercury, manual work is carried out using the built-in cover sleeves with gloves similar to the packaging of radioactive drugs. Shelters with built-in sleeves must be provided in the design of apparatus designed for manual operation associated with the release of toxic dust. The foregoing reaffirms the need for "community" of technologists and specialists in ventilation.
In industries that emit toxic gases and vapors, with modern technology most of the processes is sealed. Evolved gases and vapors are in a confined space equipment and pipes and removed from them, together with technological "tails". These latter are subjected to special treatment in order to capture and disposal, and then after the final cleaning are released into the atmosphere.
When sealed the production process, it would seem, ventilation is not needed. But the complete sealing of practice does not happen. Leakage of gases and vapors always occur through leaks equipment and pipelines working under pressure, in addition, there are specks test, measuring instruments, etc., through which the pollutant can be released. Therefore, as a rule, ventilation and arranged in a sealed process. Ventilation is general exchange or area and only partially - with local suction.
In the chemical industry and area shelters pumps suit all places possible leaks of equipment - a pilot valves, seals in pumps, sometimes even a flanged pipe connections. Shelters are small enclosures with the working apertures, performed covers of air suction. If the pumped fluid with the maximum allowable concentration of vapor 5 mg/m3 or less, it is recommended that the entire pump to enter into a casing with exhaust air out of him. If you can not cover the device in areas of possible hazards breakthrough required the installation of suction funnels PLI slits, rarely in such cases, apply suction panel.
The amount of air removed from the casing or suction devices at the zonal sealed equipment, are relatively small and range from 200 to 1000 m3 / h. Only under very toxic substances extracted air volumes exceed 1000 m3 / h. However, the number of small suction is sometimes significant - up to 30 or even 40 points.
When pressurized equipment bulk of the air is removed general ventilation, except for industries that operate with extremely toxic substances. In the latter applies kapsyulyatsiya equipment in cabins, shelters such as "pipe in pipe", etc.
In some cases it is impossible to determine the amount of pollutant (n gaseous vapors) into the air space. Consequently, it is impossible to determine the airflow calculation. In the chemical industry often have to prescribe air for general ventilation on the basis of empirical evidence, namely, the multiplicity of exchange. Such a definition of air allowed 4.9 SNIP II-F. 7-62.