Pollution control system for kiln exhaust

Abstract

Disclosed is a method and apparatus for the reduction of organic compounds and other emissions from an industrial plant utilizing a cement or minerals kiln that has a high level of organic compound emissions. The invention consists of a filter for the control of particulate emissions which has been treated with a catalyst to provide catalytic destruction of gaseous emissions as process gases are passed through the porous medium of the filter.

We claim: 
     
         1 . A method for the reduction of contaminant emissions including organic compounds present in vapor form from the process gases of an industrial plant utilizing a kiln and/or calciner to heat treat a raw material, said method comprising
 (i) directing plant process gas containing entrained particulate matter and contaminant emissions from the plant to a pollution control device comprising a process gas inlet and process gas outlet and an interior portion located intermediate the inlet and outlet, said interior portion containing at least one filtering element for removing the particulate matter from the gas, said at least one filtering element containing at least one catalyst for removing some of the contaminant emissions;   (ii) directing the process gas through the inlet and thereafter through the filtering element, wherein entrained particulate matter is separated from the process gas and the process gas comes in contact with the at least one catalyst to thereby reduce the contaminant emissions contained in the gas ; and   (iii) directing cleaned process gas through the outlet of the pollution control device.   
     
     
         2 . The method of  claim 1  further comprising:
 removing the separated particulate matter from the pollution control device. 
 
     
     
         3 . The method of  claim 1  wherein the process gas is comprised of at least one of kiln off gas, preheater off gas, precalciner off gas, raw material milling system off gas, solid fuel milling system off gas product cooler vent gases and kiln process product milling off gases. 
     
     
         4 . The method of  claim 3  wherein the process gases comprise product cooler vent gases. 
     
     
         5 . The method of  claim 1  wherein the process gases within the pollution control device are maintained at a temperature between 80° C. and 450° C. 
     
     
         6 . The method of  claim 1  wherein the at least one catalyst is selected from the group comprising vanadium, platinum, palladium, ruthenium, titanium, lanthanum, cerium, yttrium, zirconium, tungsten, manganese, niobium, molybdenum, nickel, iron and copper. 
     
     
         7 . The method of  claim 1  wherein the filtering element is a fiberglass bag. 
     
     
         8 . The method of  claim 1  wherein the filtering element is treated with a membrane. 
     
     
         9 . The method of  claim 1  wherein the filtering element is a porous ceramic structure. 
     
     
         10 . The method of  claim 1  wherein at least one reactive agent is contacted with the at least one catalyst agents to increase the reduction of hydrocarbons present in the filtering elements. 
     
     
         11 . The method of  claim 10  in which the at least one reactive agent is selected from the group comprising ozone, peroxide, potassium permanganate, calcium chloride, sodium hydroxide, sodium bromide, bromine and chlorine. 
     
     
         12 . The method of  claim 2  wherein removal of the separated particulate matter from the pollution control device is achieved by pulsing gas through the filtering elements. 
     
     
         13 . The method of  claim 2  wherein removal of the separated particulate matter from the surface of the filtering elements is achieved through sonic or ultrasonic vibration. 
     
     
         14 . The method of  claim 2  wherein removal of the separated particulate matter from the surface of the filtering elements is achieved through mechanical removal of particulate matter with a solid object. 
     
     
         15 . The method of  claim 2  further comprising:
 returning the removed particulate matter to the industrial plant process. 
 
     
     
         16 . The method of  claim 1  in which the organic compounds comprise Total Hydrocarbons. 
     
     
         17 . The method of  claim 1  wherein the organic compounds comprise at least one of formaldehyde, acetaldehyde, xylene, benzene, styrene, and naphthalene. 
     
     
         18 . The method of  claim 1  wherein the organic compound comprise Volatile Organic Compounds. 
     
     
         19 . The method of  claim 1  in which mercury compounds within the process gas are oxidized by the at least one catalyst. 
     
     
         20 . The method of  claim 1  wherein at one of nitrogen oxides, dioxin/furan emissions and carbon monoxide are reduced by the at least one catalyst. 
     
     
         21 . The method of  claim 1  further comprising injection of a sorbent upstream of the pollution control device for the adsorption of at least one of sulfur dioxide, sulfur trioxide, arsenic, thallium, mercury, hydrogen chloride, hydrogen fluoride, or hydrogen bromide. 
     
     
         22 . The method of  claim 21  wherein the sorbent includes at least one of calcium oxide, calcium hydroxide, trona, sodium bicarbonate, cement kiln dust, calcined material, and activated carbon. 
     
     
         23 . The method of  claim 19  wherein a nitrogenated agent is introduced to increase the reduction of nitrogen oxides. 
     
     
         24 . The method of  claim 23  wherein the nitrogenated agent includes at least one of ammonia, urea, ammonium bisulfate, or flyash. 
     
     
         25 . The method of  claim 1  further comprising injection of a sorbent downstream of the pollution control device for the adsorption of at least one of sulfur dioxide, sulfur trioxide, arsenic, thallium, mercury, hydrogen chloride, hydrogen fluoride, or hydrogen bromide. 
     
     
         26 . The method of  claim 25  wherein the sorbent includes at least one of calcium oxide, calcium hydroxide, trona, sodium bicarbonate, cement kiln dust, calcined material, and activated carbon.