Abstract: Disclosed are a process and apparatus for selective catalytic reduction of NOx. The process is enabled by bypassing a heat exchanger section, such as an economizer, of the boiler in advance of an SCR unit at low load conditions to enable NOx reduction even at low loads using urea instead of ammonia. In a preferred form, under high load conditions, the bypass can be almost fully closed and the economizer can be operated normally without excessively cooling the combustion gases, using only a portion of bypassed gases which are hot enough to decompose the urea into its active components including ammonia.

Abstract: Disclosed are a process and apparatus for selective catalytic reduction of NOx. The process is enabled by bypassing a heat exchanger section, such as an economizer, of the boiler in advance of an SCR unit at low load conditions to enable NOx reduction even at low loads using urea instead of ammonia. In a preferred form, under high load conditions, the bypass can be almost fully closed and the economizer can be operated normally without excessively cooling the combustion gases, using only a portion of bypassed gases which are hot enough to decompose the urea into its active components including ammonia.

Abstract: Disclosed are a process and apparatus for selective catalytic reduction of NOx. The process is enabled by passing a heat exchanger section, such as an economizer, of the boiler in advance of an SCR unit at low load conditions to enable NOx reduction even at low loads using urea instead of ammonia. In a preferred form, under high load conditions, the bypass can be almost fully closed and the economizer can be operated normally without excessively cooling the combustion gases, using only a portion of bypassed gases which are hot enough to decompose the urea into its active components including ammonia.

Abstract: The present invention relates to a process for the use of a urea hydrolysate for nitrogen oxides reductions. More particularly, the process involves forming a urea hydrolysate under conditions of low pressure and introducing the hydrolysate into a combustion effluent under conditions effective for the reduction of nitrogen oxides.

Abstract: Improved processes and improved compositions reduce the environmental damage caused by large-scale combustion, especially in the field of NO.sub.x reduction by selective noncatalytic reduction (SNCR) in the gas phase. In one aspect, the process improves the reliability of known means, compositions and methods for reducing the concentration of pollutants in a gas stream by: preparing an aqueous solution comprising a pollutant-reducing agent and a water-dispersible polymer, and introducing the solution into the gas stream. Preferred polymers comprise high molecular weight polymers selected from the group consisting of homo and copolymers of acrylic acid and acrylamide with RSV values of at least 10, sodium acrylate acrylamide copolymers with RSV values of at least 10, sulfonmethylated acrylamide/acrylamide/acrylic acid terpolymers of RSV of at least 18, alkylene oxide polymers and copolymers, and mixtures of any of these and like polymers.

Abstract: A method for removing carbonyl sulfide from fluids, particularly gases, involves contacting them with alkaline aqueous solutions containing peroxide and hindered amine. The sulfur products so formed can then be separated from the fluid. In one embodiment, gas containing carbonyl sulfide is cycled through a wet scrubber containing a solution of hydrogen peroxide and methyldiethanolamine, triethylamine, dimethylmonoethanolamine, diethylmonoethanolamine, triethanolamine, 2-amino-2-meth-yl-1-propanol, and/or 1,8-p-menthanediaminemethyldiethanolamine at a pH of about 9 to 11, e.g., about 10. Methyldiethanolamine is preferred in one embodiment. A dispersant such as a water-soluble polymer having a molecular weight of about 500 to 100,000 may optionally be employed in the solution. Abatement of greater than 90% of the carbonyl sulfide is achieved in preferred embodiments.

Abstract: More reliable removal of sulfur oxides (SO.sub.x) from combustion effluents by in furnace injection is achieved by stabilizing slurries of calcium carbonate (limestone), calcium oxide (lime) and calcium hydroxide (hydrated lime) for extended periods of time and during in-furnace injection. The slurries are stabilized by a stabilization system comprising a generally hydrophobic surfactant having an HLB of less than about 8 and a more hydrophilic surfactant having an HLB of at least about 8, wherein the HLB values of the hydrophobic and the hydrophilic surfactants differ by at least about 3.

Abstract: Improved processes and improved compositions reduce the environmental damage caused by large-scale combustion, especially in the field of NO.sub.x reduction by selective noncatalytic reduction (SNCR) in the gas phase. In one aspect, the process improves the reliability of known means, compositions and methods for reducing the concentration of pollutants in a gas stream by: preparing an aqueous solution comprising a pollutant-reducing agent and a surface active agent in ratio of surface active agent to pollutant-reducing agent of greater than 1:4000, the amount and composition of surface active agent being effective to reduce average droplet size by at least 10%, and introducing the solution into the gas stream. Preferred surface active agents have HLB values of from about 8 to about 20, and are preferably anionic or nonionic agents such as C.sub.11 -C.sub.15 secondary alcohol ethoxylates, C.sub.12 -C.sub.

Abstract: More reliable removal of sulfur oxides (SO.sub.x) from combustion effluents by in furnace injection is achieved by stabilizing slurries of calcium carbonate (limestone), calcium oxide (lime) and calcium hydroxide (hydrated lime) for extended periods of time and during in-furnace injection. The slurries are stabilized by a stabilization system comprising a generally hydrophobic surfactant having an HLB of less than about 8 and a more hydrophilic surfactant having an HLB of at least about 8, wherein the HLB values of the hydrophobic and the hydrophilic surfactants differ by at least about 3.

Abstract: The present invention relates to a process for reducing the nitrogen oxides level in an effluent from the combustion of a carbonaceous fuel, which involves preparing an emulsion of a nitrogen oxides reducing treatment agent and a hydrocarbon having a boiling point which is lower than that of said nitrogen oxides reducing treatment agent; and introducing said emulsion into the effluent from the combustion of a carbonaceous fuel under conditions effective to reduce the nitrogen oxides level therein.

Abstract: The present invention relates to a process for the use of a urea hydrolysate for nitrogen oxides reductions. More particularly, the process involves forming a urea hydrolysate and introducing the hydrolysate into a combustion effluent under conditions effective for the reduction of nitrogen oxides.

Abstract: A process for reducing nitrogen oxides in a combustion effluent is presented. The process involves introducing a nitrogenous treatment agent other than ammonia into the effluent to create a treated effluent having reduced nitrogen oxides concentration such that ammonia is present in the treated effluent; introducing a source of ammonia into the effluent; and contacting the treated effluent with a nitrogen oxides reducing catalyst.