Internal-combustion engines – Miscellaneous – Fuels – lubricants and additives
Patent
1999-01-28
2000-12-12
Moulis, Thomas N.
Internal-combustion engines
Miscellaneous
Fuels, lubricants and additives
123 25R, F02B 7512
Patent
active
061583979
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a method for the reduction of the carbon black content in the waste gas of a diesel engine and a device to carry out this method.
As in the past, the emission of carbon black and NO.sub.x represents one of the greatest problems of the diesel engine. All previous strategies for the reduction of pollutants exhibit a "see-saw" effect between the carbon black and NO.sub.x waste gas concentration. By a time shift of the beginning of the injection in the direction of a later injection, it is possible to reduce the formation of carbon black, but this leads to higher NO.sub.x emissions. The waste gas recycling method, on the other hand, makes possible a reduction of the NO.sub.x production by the lower temperatures in the engine, but involves a strongly increased carbon black emission.
By additional injection of water into the combustion chamber, it is possible to reduce the NO.sub.x formation by reducing the combustion temperature--see Amin Velji et al., MTZ Motorentechnische Zeitschrift 57 (1996) 7/8, 400-407. A simultaneous reduction of the carbon black emission is attained only if water in the form of a diesel-water emulsion is introduced into the combustion chamber, but not if water is introduced into the combustion chamber with the combustion air or directly by a stratified injection.
From European Patent No. B 0,333,704, a method is known for reducing the fraction of harmful substances in the waste gas--namely CO, HC, and NO.sub.x --of a combustion process, in which hydrocarbon compounds participate, by supplying a liquid composition which contains a peroxide, such as hydrogen peroxide or another peroxy compound and water, into the combustion process--with the combustion air and/or the fuel-air mixture. The supply to the combustion process takes place in that known method already during the introduction or within the ignition phase of the combustion process. A carbon black reduction in the waste gas cannot be attained in the method execution indicated in this document. The liquid composition can contain 10 to 80 vol % hydrogen peroxide, which decomposes into OH radicals in the combustion chamber, which, in turn, favor the combustion.
SUMMARY OF THE INVENTION
The goal of the invention is to reduce the carbon black emission during the diesel motor combustion, using peroxy compounds, wherein, at the same time, the NO.sub.x emission should not be negatively influenced and preferably should be lowered simultaneously.
The desired goal of a reduction of the carbon black content in the waste gas of a diesel engine, into whose combustion chamber diesel fuel is injected and burned in cycles, is attained, in accordance with the invention, in that after the beginning of the injection and combustion of the fuel, liquid containing a peroxy compound from the series of hydrogen peroxide and other peroxy compounds, in particular, organic peroxy compounds, is supplied to the combustion chamber.
Hydrogen peroxide or the peroxy compound is appropriately supplied in the form of a water-containing liquid, usually in the form of a solution. The other peroxy compounds are--except for H.sub.2 O.sub.2 --organic peroxy compounds, such as peroxy carboxylic acids and hydroperoxides. Peroxy salts are generally less suitable because of the incrustation which thereby arises. Particularly preferred is an aqueous H.sub.2 O.sub.2 solution with a content of 10 to 75 wt %, in particular, 30 to 50 wt %.
The invention is based on the idea of eliminating carbon black particles formed during the combustion of diesel fuel toward the end and, in particular, following the combustion phase with the aid of hydrogen peroxide or another peroxy compound, supplied at this time to the combustion process, at least extensively by combustion.
During the diesel engine combustion process, carbon black is formed in the combustion phase following the self-ignition; this carbon black, however, is again oxidized, for the most part, by the OH radicals still present during this phase. The combustion phase is concl
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Antoni Christian
Born Caroline
Peters Norbert
Plessing Tobias
Degussa - Aktiengesellschaft
Moulis Thomas N.
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