Controle de emissões de poluentes em motores a diesel

Abstract

Although diesel engines are extremely efficient, thecomponents discharged by these engines are harmful to health, damaging the populationhealth.The aromatic hydrocarbons formed during the incomplete combustion of carbon-containing materials, especially coal and petroleum affect atmospheric equilibrium and may suffer nitration reactions and atmospheric oxidation, which result in generation ofphototoxins and genotoxic which resultsforest destruction, and the gases released in the exhaust of diesel fuel combustion releasescarbon monoxide, which sharply confined environment can cause death and long term respiratory diseases, and other chemicals such as sulfur oxide and nitrogen oxide that can cause lung cancer. For these reasons and to control environmental pollution, the Kyoto Protocol was signed by several nations.The International Maritime Organization (IMO), through MARPOL (Marine Pollution -7378) issued guidelines to curb environmental pollution by vessels.The article "Pollution Generated by Internal Combustion machines Moved Diesel" published by Quim. New, Vol 27, No. 3, 472 -. 482, 2003, diesel oil is a derivative,consisting of aliphatic hydrocarbons having 9-28 carbon atoms in the chain and sulfur in concentrations ranging from 0.1 % to about 0.5%, which when burned produces carbon monoxide, hydrocarbons, nitrogen oxide, sulfur oxide and particulate matter, which can cause injuries in humans asseen above, and for this reasonit isregulated by specific legislation. There are also other components of burning diesel as aldehydes, ammonia, benzene, cyanide, the toluene and polynuclear aromatic hydrocarbons which also are not regulated.According to the National Department of Fuel (DAC),in the Brazilian domestic market is available three types of diesel namely: a) the Type A is the automotive diesel used in diesel engines and small heating installations; b) type B is the metropolitan diesel which is used for automotive application, differing from the type A to possess no more than 0.5% sulfur and are sold in metropolitans areas like Rio de Janeiro, Porto Alegre, Curitiba, São Paulo, Belo Horizonte, Salvador, Recife, Fortaleza and Aracaju .; c) the Dtype is the marine diesel. This type of diesel is produced specifically for use in marine vessels engines, thediesel has to have specifiedits flash point in at least 60° C.Diesel fuel A and B, gets refinery additives designed to improve the performanceof this fuel. Among these additives may be mentioned the de-emulsifiers, antifoams, dispersants and corrosion inhibitors.The use of these additives is intended to prevent diesel emulsion form with water, thus hindering their separation from the product and preventing its drain. It also allows complete filling of the tanks of the vehicles, which was previously hampered by the additive foam generation. In addition to these factors, the additives serve to keep clean the fuel system and the combustion chamber, increasing the useful life of the engine, thus minimizing the emission of polluting and optimizing fuel efficiency.There are two main strategies to control pollution ofatmosphericfromemissions produced by burning diesel. The first is to improve the quality of the produced diesel fuel, i.e., with lower pollutant content and the second is to hold, through filters, pollutants, preventing them from reaching the atmosphere.Apart from this there are other two strategies such as those adopted by Japan, Sweden and the State of California in the United States of North America, theydecided to reduce diesel emissions bytaking the steps: a) shut down the engines for ships at pier, supplying them with energy from shore; b) recommend the treatment of exhaust gases in order to reduce emissions; c) reducing the speed of ships in port; d) apply reduced rates to ships in port to adopt the regulations of these countries / state, and in these conditions, vessels which have lowemissions of nitrogen oxide have lower rates and vice versa.