초록 ▼

Pollution from industrial plants which produce NOx and waste water is reduced by utilizing waste water to prepare aqueous NOx-reducing solutions. Total water hardness in the waste water is preferably maintained below 2500 ppm, silicate below 200 ppm and the calcium to magnesium ratio above 2:1. The

Pollution from industrial plants which produce NOx and waste water is reduced by utilizing waste water to prepare aqueous NOx-reducing solutions. Total water hardness in the waste water is preferably maintained below 2500 ppm, silicate below 200 ppm and the calcium to magnesium ratio above 2:1. The aqueous NOx-reducing solution will preferably contain hardness suppressing compostions in effective amounts.

대표청구항 ▼

An improvement in a process for controlling emissions which conserves water usage and reduces waste water discharge, the process including burning fuel with air to produce heat and utilizes water as a heat transfer medium, the process resulting in the production of waste water and combustion gases c

An improvement in a process for controlling emissions which conserves water usage and reduces waste water discharge, the process including burning fuel with air to produce heat and utilizes water as a heat transfer medium, the process resulting in the production of waste water and combustion gases containing NOx, and introducing an aqueous solution of NOx-reducing agent into the combustion gases under conditions effective to reduce the NOx concentration thereof, the improvement comprising: recovering the waste water at the site of combustion; mixing a NOx-reducing agent with the waste water and a hardness-suppressing composition in sufficient quantities to provide an aqueous solution of the NOx-reducing agent effective for reducing the NOx concentration of the combustion gases while moderating the tendency for precipitation of hardness factors; wherein the aqueous solution of NOx-reducing agent is prepared by admixing said waste water, an effective NH-containing composition, and a hardness-suppressing composition comprising at least one member selected from the group consisting of water-soluble or water-dispersible polymers, phosphonates, chelants, phosphates and mixtures thereof, of a composition and in an amount effective to moderate the tendency for precipitation of hardness factors comprising at least calcium; and wherein the NOx-reducing agent comprises an NH-containing composition comprising a member selected from the group consisting of ammonia, urea, urea hydrolysis products, carbamates, ammonium carbonate, ammonium bicarbonate, cyanurates, ammonium salts, and mixtures of two or more of these; following mixing of the NOx-reducing agent with the waste water and a hardness-suppressing composition, contacting the combustion gases with the aqueous solution of NOx-reducing agent under conditions effective to achieve selective gas phase reaction of the NOx-reducing agent with the NOx.