A NOVEL EXHAUST AFTER-TREATMENT SYSTEM FOR A DIESEL ENGINE OR A SPARK IGNITION GASOLINE, CNG,LNG, ENGINE

摘要

Internal Combustion Engines, both Compression-Ignition (CI), mainly for Diesel oil, and Spark Ignition, for Gasoline, Compressed Natural Gas (CNG) or LPG emit pollutants during operation but particularly during cold startup in addition to nitrogen, carbon dioxide and water. The POLLUTANTS are: Carbon Monoxide (CO) Unburned Hydrocarbons (HC) and Nitrogen-Oxides (NOx) All cars today must be equipped with Catalytic Converters for oxidizing the CO to C02 and the HC to C02 and water and for the reduction of the NOx to N2 and water. These catalysts are inactive at temperatures below ca. 300 deg.c. and so when starting an engine from cold the emission of pollutants is high and not mitigated by the catalysts. Another problem is that a Reductant is required for the reduction of the NOx to N2 and water and the reductants in the exhaust gases namely CO and HC or Ammonia or Urea added to the flue gases are not efficient enough to fulfill the more stringent requirements for very low emission of NOx, There were many suggestions, in the literature and patents that propose the use of electrical heating of the catalysts monoliths, however the high burden on the batteries and also the long time needed for the heating made this approach virtually impractical. Another approach, for the DENOx and sometimes also for the cold startup was to manufacture hydrogen from water by electrolysis and first, store hydrogen and oxygen for injection into cold catalysts and ignite it prior to injection of the main fuel to the engine and secondly, during the run to produce hydrogen to be used as the reductant of NOx This approach also proved to be too difficult and costly and altogether impractical. In the present invention here an auxiliary small fuel system, preferably alcohol like Methanol, is installed. At cold startup the injection of the main fuel, such as Diesel Oil for CI engines or Gasoline for SI engines, is delayed for a few seconds and the compressed air from the engine flows into the after treatment main passage and mixes with injected Methanol and the mixture flows into the first catalyst section where at the inlet a metal net connected to an electrical source, such as a car battery, is heated igniting the mixture of air-methanol until the catalyst section is heated and then, in sequence, all catalyst sections, and in the case of a Diesel Engine also the DPF (DIESEL PARTICULATES FILTER), are heated up to the effective operating temperature. At that point all Methanol supply is cut off and a Methanol-Water mix is injected to a catalytic hydrogen production section (HPC) which is installed in parallel to the main exhaust passage and the Hydrogen rich stream is injected as the redactor to the catalysts De-NOX reduction section. Now with the catalyst sections (and the DPF section FOR A DIESEL ENGINE) are hot thus fully effective, the main fuel into the engine is injected normally with all pollution abating devices fully and efficiently operational