Method and apparatus for removing dust and gas pollutants from waste gases, particularly waste gases produced in the manufacture of optical waveguide preforms
First Claim
1. Method for purifying waste gases containing pollutants in dust, gas, and/or vapor form wherein in a first step, dust is extracted, and wherein in one or more further steps, the gaseous pollutants are absorbed from the dust-free waste gas by means of an absorption liquid flowing in an absorption-liquid circulation system,characterized in that a dry, coated fabric filter is used for the dust extraction, that the pollutant concentration of the absorption liquid is measured continuously, that, when a predeterminable maximum permissible pollutant concentration is reached, part of the absorption liquid is withdrawn from the absorption-liquid circulation system and is subjected to a chemical detoxication treatment in a separate detoxication circulation system and is then introduced into a sewage system, and that in the absorption-liquid circulation system, the withdrawn part of the absorption liquid is replaced by fresh, unpolluted absorption liquid.
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Abstract
A method is disclosed for purifying waste gases containing extremely finely dispersed pollutants in dust form and pollutants in gas and vapor form, particularly for purifying waste gases produced in chemical vapor phase reactions during the manufacture of optical waveguide preforms. In a first step, dust is extracted in a dry, coated fabric filter (1). The gaseous and vaporous pollutants are then absorbed in a gas scrubber. During this gas-scrubbing process, as soon as the absorption liquid circulating in an absorption-liquid circulation system reaches a pretermined pollutant concentration, part of the absorption liquid is withdrawn from the absorption-liquid circulation system and detoxicated in a separate detoxication circulation system. The part withdrawn is simultaneously replaced by fresh, unpolluted absorption liquid. The method requires little maintenance, is fully automatic and, since the necessary chemicals are added in measured quantities, keeps chemical consumption to a minimum while fully satisfying the legal requirements for prevention of air and water pollution.
82 Citations
9 Claims
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1. Method for purifying waste gases containing pollutants in dust, gas, and/or vapor form wherein in a first step, dust is extracted, and wherein in one or more further steps, the gaseous pollutants are absorbed from the dust-free waste gas by means of an absorption liquid flowing in an absorption-liquid circulation system,
characterized in that a dry, coated fabric filter is used for the dust extraction, that the pollutant concentration of the absorption liquid is measured continuously, that, when a predeterminable maximum permissible pollutant concentration is reached, part of the absorption liquid is withdrawn from the absorption-liquid circulation system and is subjected to a chemical detoxication treatment in a separate detoxication circulation system and is then introduced into a sewage system, and that in the absorption-liquid circulation system, the withdrawn part of the absorption liquid is replaced by fresh, unpolluted absorption liquid.
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8. An apparatus for purifying waste gases containing pollutants in dust, gas, and/or vapor form, comprising:
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a dust collector including a dust filter having polytetrafluoroethylene-coated fabric filters and means for conveying said waste gases through said filter; a gas scrubber connected to said dust collector for receiving said waste gases and subjecting said waste gases to an absorption-liquid; an absorption-liquid circulation system for storing said absorption-liquid and circulating said liquid through said gas scrubber; a detoxication tank for receiving used absorption-liquid; means for automatically withdrawing absorption-liquid from the absorption-liquid circulation system as a function of the pollution concentration of the absorption-liquid, for introducing said withdrawn absorption-liquid into the detoxication tank and for automatically refilling the absorpotion-liquid circulation system with fresh absorption-liquid; and means for maintaining circulation of the withdrawn absorption-liquid through the detoxication tank and for automatically introducing a reductant, a sodium hydroxide solution, and a strong acid into the detoxication tank in amounts determined by the redox-potential of the withdrawn absorption-liquid and the pH level of said liquid. - View Dependent Claims (9)
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Specification