A method for filtering of noxious chemical substances or the like. Dust or flue gases containing

摘要

Dust-laden gas streams containing a chemically toxic or noxious component are initially passed through a first pocket filter to remove particulate matter and then may be charged with an additive capable of binding the toxic or noxious components in the form of solid particles which are entrained by the prepurified gas stream to a second pocket filter. The particulate layer containing the additive and deposited upon the latter filter surface is periodically dislodged and reentrained by the gas stream onto the filter surface until the quantity of additive which is deposited on the second filter surface is between 100 and 1,000 times the quantity per hour of the additive charged into the prepurified gas stream. Equilibrium is then maintained between collected solids on the second filter surface as additive solids are carried onto the latter so that the quantity of the additive withdrawn per hour as collected from the filter is equal to the quantity per hour of the additive charged into the prepurified gas stream.