Abstract:
A process is presented for reducing the concentration of pollutants in an effluent from the combustion of a carbonaceous fuel. The process comprises injecting a first treatment agent into the effluent at a first temperature zone and injecting a second treatment agent into the effluent at a second temperature zone, wherein the first and second treatment agents are injected under conditions effective to reduce the effluent pollution index.
Abstract:
A safe, reliable SCR system for reducing NOx emissions from an internal combustion engine hydrolyzes urea or like reagent under sufficient pressure to assure generation of ammonia, without production of solids that could foul injectors or catalysts. The heat for hydrolysis can be provided by the exhaust or an auxiliary means.
Abstract:
Urea is pyrolyzed in a chamber designed to facilitate gasification of the urea by pyrolysis with conversion of urea to ammonia and isocyanic acid (HNCO) with water vapor and carbon dioxide. The product gases are introduced into exhaust gases from a lean-burn engine, preferably upstream of a turbocharger. The exhaust gases are then contacted with an SCR catalyst.
Abstract:
A safe, reliable SCR system for reducing NO.sub.x emissions from a lean-burn internal combustion engine utilizes urea in aqueous solution. A modular assembly is provided for mounting inside a urea reagent tank enables controlled feeding an aqueous urea solution to an injector. The assembly includes a reagent quality sensor, a reagent temperature sensor, a reagent level sensor and a pump.
Abstract:
Platinum group metal fuel additives are effective in fuel environments which make the exclusion of water impractical. The fuels additives comprise a platinum group metal compound and a water-functional composition selected from the group consisting of lipophilic emulsifiers, lipophilic organic compounds in which water is miscible and mixtures of these. The additives are preferably effective in fuel compositions having water contents of at least about 0.01% water by weight.
Abstract:
The invention provides a method employing a fuel additive to improve the operation of a pass-through oxidation catalyst over long periods of time with continued catalytic activity and without the undesirable conversion of SO.sub.2 to SO.sub.3. A pass-through catalyst support is continuously, selectively catalyzed by the combustion of a fuel containing a platinum group metal composition which burns to release the catalyst metal in active form. The effectiveness of the process is attributed to improved combustion in the engine by the catalyst and the treatment of the catalytic oxidizer with active catalyst metal released during combustion such that, in the exhaust system, the soluble organic fraction of the particulates and the levels of gaseous unburned hydrocarbons and carbon monoxide are significantly reduced. The catalysts conditioned by the present invention cause minimal conversion of SO.sub.2 to SO.sub.3. The platinum group metal compositions soluble or dispersible in the diesel fuel and are added in amounts effective to provide concentrations of the metal in the fuel of less than 1 part per million (ppm).
Abstract:
This invention presents a process for performing ammonia scrubbing. More particularly, the present invention comprises a process in which a non-nitrogenous treatment agent is introduced into the effluent so as to interact with ammonia present in the effluent under conditions effective to perform ammonia scrubbing, i.e., at least partially rid the effluent of ammonia.
Abstract:
A multi-stage NOx reduction system employs catalysts effective at different temperature ranges and can have reagent injectors associated with each, for use in series or in parallel. A controller directs reagent introduction to one catalyst or the other as temperature and other conditions dictate. Valving can redirect exhaust to particular catalyst zones, if necessary.
Abstract:
Emissions of pollutants from diesel engines are reduced by a combination of mechanical devices and fuel additives. In one series of embodiments, diesel emissions of NO.sub.x and particulates are reduced, simultaneously with gaseous hydrocarbons and carbon monoxide, by the combined use of exhaust gas recirculation or engine timing modification, with a particulate trap and a platinum group metal catalyst composition. In another embodiment, a multi-metal catalyst composition, comprising a combination of a platinum metal catalyst composition and at least one auxiliary catalyst metal composition, especially cerium or copper, is employed to provide catalyst metal to the exhaust system including a diesel trap to lower the balance point of the particulate trap (the temperature at which the rate of trap loading equals the rate of regeneration) while also lowering the emissions of carbon monoxide and unburned hydrocarbons. Data for platinum, copper and cerium catalysts establishes effective amounts. Tests also show selective maintenance of low oxidation of SO.sub.2 to SO.sub.3.
Abstract:
Urea or other solid NO.sub.x -reducing reagent is employed in a selective catalytic reduction process on emissions from diesel and lean-burn gasoline engines. The solid reagent is fed to a gas generator that produces a reactant gas by heating. In one embodiment the reactant gas is maintained at elevated temperatures to prevent condensation products from forming. The reactant gas contains ammonia and is fed to the exhaust on an as-needed basis.