Diesel Emission and Reduction Processes

Contents

Diesel Emission and Reduction Processes1

Introduction3

Discussion3

Alternative Fuels5

Modification of Combustion6

Increase Injection Pressure6

Modification of injector specification7

Change in number of injectors7

Diesel Oxidation Catalyst9

Selective Catalytic Reduction9

NOx Adsorbers10

Closed Crankcase Filters10

Scavenge /Charge Air cooling10

Water Injection11

Exhaust Gas Re circulation11

Conclusion12

References13

Diesel Emission and Reduction Processes

Introduction

There are several health risks and hazards associated with diesel engines especially due to oxides of nitrogen and particle emission (PM). There are also certain ways to control the exhaust of diesel. Today, diesel emission control can control all the gases exhaust from diesel engine, such carbon mono oxide, hydrocarbons, matter, oxides of nitrogen and air pollutants. With the help of these controls, air quality can be made better.

Discussion

Emission of exhaust from diesel engine creates much health problems in Unites States. The problems include young mortality, respiratory problems, cardiovascular disease, asthma, and defects in lungs. Road diesel vehicles produced 25% of the oxides of nitrogen (NOx) and 23% PM10 Radiations. It is found that old diesel vehicle can produce 8 tons of pollution per year. In total life of the engine, it can produce 160 to 240 tons of pollution. A heavy truck can also produce the same amount of pollution as 150 passenger cars. Diesel produces tine particles, which consists of carbon core and very toxic to lungs. They directly inserted into the respiratory system where there are large industries in urban population.

There are also particulates of Sulphur Oxides (SOx) are present which are due to the presence of sulphur in exhaust gases. During the combustion process, sulphur oxidizes to form sulphur dioxide and sulphur trioxides. The fuels, which contain low sulphur quantity, are expensive. Companies are forcing to reduce the sulphur content and the process of desulphurization. The desulphurization can be easily achieved by wet scrubbing. The fuel gas passes through the quencher to cool down there and reach the saturation temperature. It is washed out with the neutralizing agent such as sea water in a scrubber. The risks of using diesel fuels with sulphur contents are that it is corrosive. It is dangerous and toxic to the environment, as sulphur dioxide and sulphur trioxide, when combine with atmosphere it forms Sulpheric Acid, and cause the acid rain to occur which is dangerous to the physical life, and environmental damage

Figure :- Typical emissions from low speed

Diesel engine

Pollutant

NOx

CO

HC

CO2

SO2

Medium

Speed

Engines

(g/kWh)

1.2

1.6

0.5

660

4.2x%S

where S =

content

Low

Speed

Engines

(g/kWh)

17

1.6

0.5

660

4.2x%S

sulphur

(%m/m)

Table 3.1:- Emission comparison between low and medium speed diesels engines.

Carbon dioxide is also one of the major products for combustion. There is no such effective method to reduce the emission of carbon dioxide because whenever there is combustion processes emission of carbon dioxide is mandatory. The only way is to reduce the amount of fuel which stops the emission of carbon dioxide. Carbon dioxide is non toxic but lead to green house effects and global warming.

Carbon mono oxide is typically formed when there is incomplete combustion. It is due to the incomplete combustion of hydrocarbons where oxidation process does not give proper time for the reaction occurring. There are also sufficient amount of hydrocarbons emission, which is due to the non sufficient ...