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Air Pollution Control Systems for Boiler and Incinerators.Unique control problems_6

Tham khảo tài liệu 'air pollution control systems for boiler and incinerators.unique control problems_6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Sim poiPDF Mergeíand Split Unregistered Version - http www.simpopdf.com baghouses are used when dust concentrations are high and continuous filtering is needed. 9-3. Fabric characteristics and selection Fabric filter performance depends greatly upon the correct selection of a fabric. A fabric must be able to efficiently collect a specific dust be compatible with the gas medium flowing through it and be able to release the dust easily when cleaned. Fiber yarn structure and other fabric parameters will affect fabric performance. At the present time the prediction of fabric pressure drop collection efficiency and fabric life is determined from past performance. It is generally accepted practice to rely on the experience of the manufacturer in selecting a fabric for a specific condition. However the important fabric parameters are defined below to aid the user in understanding the significance of the fabric media in filtration. a. Fabric type. The two basic types of fabric used in filtration are woven and felted. The woven fabric acts as a support on which a layer of dust is collected which forms a microporous layer and removes particles from the gas stream efficiently. A felted material consists of a matrix of closely spaced fibers which collect particles within its structure and also utilizes the filter cake for further sieving. Filtering velocities for woven fabrics are generally lower than felts because of the necessity of rebuilding the cake media after each cleaning cycle. It is necessary that woven fabrics not be overcleaned as this will eliminate the residual dust accumulation that insures rapid formation of the filter cake and high collection efficiencies. Felts operate with less filter cake. This necessitates more frequent cleaning with a higher cleaning energy applied. Woven products usually more flexible than felts may be shaken or flexed for cleaning. Felts are usually back-washed with higher pressure differential air and are mainly used in pulsejet .