Packed Bed Type Wet Scrubbers
and Degasers are used for removal of gas, vapors, chemical mist etc. These scrubbers are cylindrical towers and are packed with plastic tower packing or any-other suitable packing material for particular application. The scrubbers are provided with a water spraying arrangement, which can be supplied in various sizes with gas velocities ranging from 0.5m/sec. to 2m/sec and pressure drop between 50mmwg and 750 mmwg. Fumes / Gaseous contaminants travel vertically upwards while caustic liquid / water is sprayed from the top, over the tower packing. The liquid is recirculated with pump. Additionally, packed bed scrubbers offered, mostly counter current scrubbers, which can collect efficiently particulates up to a size of 4 - 5 micron.
Packed towers are used as contacting equipment for gas-liquid and liquid-liquid systems. It presents a cross-section of a typical unit. The shell is usually cylindrical, although square wooden, light metal, or .reinforced plastic towers are used. The basic unit consists ofOther Details:
- Packing (one or more sections)
- Packing support(s)
- Liquid distributor (s)
- Intermediate supports and redistributors
- Gas and liquid entrance and exit nozzles
- The shell may be of metal (steel, alloy, or non-ferrous). plastic, wood or some combination which may require the addition of liners or inner layers of rubber, plastic or brick
- The mechanical problems of attaching inner nozzles, supports and brick require considerable attention that is not an integral part of sizing the equipment.A shows a typical large steel brick-lined-membrane fined tower with corbeled brick support locations
- In these towers, temperature and/or corrosive conditions usually dictate the internal lining, and the selection of the proper acid-(or alkali-) proof cements
- Ceramic, plastic and other non-metal tower shells are used quite often.
- It is important to consider in ceramic construction that the main inlet or outlet nozzles or any other large connections should be oriented 90° to each other to reduce the possibility of cracking the walls, as most cracks go one-half diameter
- Preferably there should only be one nozzle at any one horizontal plane. The nozzles should never carry any piping or other stress load
- The bell and spigot type tower, is satisfactory for 2 to 2.5 psi in 12-inches diameter. to 30-inches diameter.towers when the joints are packed with asbestos and caulking compound.
- For operating pressures of 5 psi in 18-inches through 48-inches diameter., use asbestos and silicate cement?- Special hold-down packing gland-type rings will allow operation at slightly higher pressure. The porcelain towers should be used for the higher pressures rather than the weaker stoneware
- The rate of heating or cooling a stoneware or porcelain tower should not exceed 15° F. per minute