Abstract: A method and improved apparatus is disclosed for improving combustion efficiency and reducing emission of gaseous pollutants during the manufacture of cement in conventional long rotary kilns. Air is injected through a port in the wall of a rotary cement kiln having a secondary burning zone established by burning solid fuel in contact with the in process mineral at a point downstream, relative to kiln gas flow of the clinkering zone in the kiln. The air injection apparatus is designed to enhance mixing of the injected air with the kiln gas stream and is characterized by high linear flow rates and/or multi-directional air injection ports. The air injection ports can be located downstream of a secondary burning zone to provide staged combustion with concomitant reduction in concentration of NO.sub.x, CO and hydrocarbons in the kiln gas stream.

Abstract: The present invention relates to methods for selectively reducing NO.sub.x so that nitrogen can be removed from emission effluent streams and NO.sub.x emissions can be reduced to very low levels. In addition, the present invention teaches a method whereby NO.sub.x and SO.sub.x may be simultaneously removed from the effluent stream.The present invention teaches the reduction of NO.sub.x with cyanuric acid. Initially, cyanuric acid is decomposed to form decomposition products. The reaction of cyanuric acid to produce its decomposition products, such as isocyanic acid or related reaction intermediates, takes place in an oxygen-free, fuel rich, decomposition zone with the reaction temperature in the range of from about 1000.degree. F. to about 3000.degree. F.After the cyanuric acid is decomposed in the absence of oxygen, the decomposition stream is mixed with the effluent stream containing NO.sub.x. At this point the oxygen level of the stream must be carefully controlled to provide an excess of oxygen.

Abstract: The present invention relates to methods for selectively reducing NO.sub.x so that nitrogen can be removed from emission effluent streams and NO.sub.x emissions can be reduced to very low levels. In addition, the present invention teaches a method whereby NO.sub.x and SO.sub.x may be simultaneously removed from the effluent stream.The present invention teaches the reduction of NO.sub.x with --NH and --CN containing selective reducing agents such as ammonium sulfate, urea, and NH.sub.3. Initially, the selective reducing agent is decomposed in a fuel-rich environment to form highly reactive decomposition products. The reaction of the selective reducing agent to produce its decomposition products, such as NH, NH.sub.2, and related reaction intermediates, takes place in an oxygen-free, fuel-rich decomposition zone with the reaction temperature in the range of from about 300.degree. F. to about 2400.degree. F.

Abstract: The following specification discloses a process and burner for combusting fossil fuels such as coal to provide low SO.sub.x and NO.sub.x emissions. The process includes pulverizing the coal together with an alkaline material, such as limestone in an amount calculated to provide an alkaline metal stoichiometric equivalent of one to seven times the stoichiometric equivalent of the sulphur contained in the coal. The resulting pulverized coal-limestone mix is then combusted under fuel rich conditions. For example, 25% of the theoretical air required to combust the coal is preheated and injected into the combustion zone together with the pulverized coal-limestone mixture. The primary or transport air is swirled to increase mixing and to stabilize the flame. Preheated secondary air is introduced to the combustion zone. The amount of the preheated secondary air amounts to approximately 40% to about 100% of the theoretically required air.