The Best Tutorial On| Emission From Diesel Engines

Emission from diesel Engines

Introduction

In this post on Emission from diesel Engines, we will discuss Diesel Exhaust Emissions, Emission reduction technology, and their control.

What are the emissions from a diesel engine?

Emission from the exhaust gas of a Diesel consists of the following.

1. Oxides of nitrogen(NOX)
2. Oxides of Sulphur (SOX)
3. Particulate Matter (PM)
4. Oxides of Carbon as Carbon dioxide (CO2)
5. CO (Oxides of Carbon as Carbon Monoxide)
6. Volatile Hydrocarbons from Lube oil and unburnt fuel (HC)

Oxides of nitrogen

Despite the fact, NOx consists of nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O), dinitrogen pentoxide (N2O5).NOx’s primary reference is to NO and NO2.

In combustion processes, NOx formation is inevitable because the oxidation of N2 forms thermal NOx by O2 in the air. NOx is an unwelcome by-product of combustion because it is recognized as an air pollutant and induces secondary pollutants such as photochemical chemical smog.

An atmospheric state where a blend of gaseous photochemical oxidants, solid nitrate, and sulfate remains at an elevated combination is Photochemical smog. Acid rain and photochemical oxidants are the cause of NOx.

Oxides of Sulfur (SOX)

Principally, SOx consists of sulfur monoxide (SO), sulfur dioxide (SO2), and sulfur trioxide (SO3). Because SO instantly oxidizes into SO2 and is not decomposable at room temperature under atmospheric pressure. Therefore, it refers to SO2 and SO3.

Despite the fact observation of SO2 is as gas or molecules and SO3 is as PM. In combustion processes, sulfur in fuel leads to the formation of SOx.

Commonly in cases associating fossil fuels like petroleum and coal, observe SOX formation. SOx is an unacceptable by-product because its consideration is as an air pollutant along with NOx. SOx is the leading cause of fog.

Particulate Matter (PM)

PM is either a solid particle in liquid droplets. Aerosol in Atmosphere is also Particulates. Commonly hanging particulate element confirms to a particle with 10 mm or less in size.

Origination of PM is due to the emission of soot, smog, and fly ash in carbon.

Particulates hanging in the Atmosphere in heavy concentrations are air pollution.

Inhaling PM will negatively affect the human and other living being’s health because PM deposits in the lungs and respiratory tract.

PM Emissions from the diesel engine are a severe problem universally.

The fuel of Diesel engines contains a heavy amount of sulfur.

During the combustion process in diesel engines, sulfur produces SOx, i.e., SO2 and sulfate, a PM type.

Oxides of Carbon as Carbon dioxide (CO2)

Carbon dioxide emissions from the Diesel engine exhaust is approximately 6 %. Carbon dioxide is non-toxic but has a significant share in Global Warming (Greenhouse Effect) and being the cause of Earth’s atmosphere change.

Carbon dioxide is the unavoidable output of the combustion of fossil fuels.

Due to the higher thermal efficiency of Diesel engines, emissions from Diesel engines are lower than any other heat engines.

Efficient fuel combustion will produce less carbon dioxide. The amount of carbon dioxide production is directly proportional to the volume of fuel-burning (Relates with the plant efficiency).

Changeover of fuel from Heavy fuel oil to natural gas, hydrogen, or biofuel to decreases the CO2 emission.

Emission Reduction Technology -Emission from Diesel Engines)

The diesel engine has the advantage of lower carbon dioxide due to its more efficiency and compact size.

Besides the fact due to the presence of harmful particulates and NOx in the Diesel Engine emissions, it is mandatory to control the emissions with the latest technology.

Marine diesel exhaust emission has a high NOx concentration to the tune of 500e1000ppm. Furthermore, diesel emissions contain sulfur oxides (SOx) and PM.

Due to the low rpm of the Diesel Engine and the Initiation of emissions at a slow rate, it is easy to manage emissions control.

From the environmental safety aspects, for the reduction of emissions and the improvement of efficiency in Diesel Engine Fuel injection system is the leading technology, since this technology enhances the combustion.

The impulsive Valve timing system is the automated regulation mechanism. Closing the intake valve before the bottom dead center will lower the combustion temperature and minimize the effective compression ratio. This operation of the valve timing will result in emission reduction.

Fuel is injected with an abundance ratio of surface area to the volume by a more significant number of most minute particles. This form of injected fuel produces enhanced vaporization from the size of the fuel globules. This complete process results in perfect and cleaner combustion with reduced NOx and Particulates emissions.

Injection of a small amount of fuel into the pre-combustion chamber creates ignition delay.

Prevention of rapid ignition by the method of ignition delay minimizes the NOx. In the following list, we are describing, in brief, the Emission reduction techniques for diesel engines

1. A common-rail fuel injection system — the new emission control technologies use the common rail fuel injection system.
2. Fuel pre-treatment:- Fuel pre-treatment reduces the causes that lead to the emergence of pollutants in fuel. An advantage of the pre-treatment is that it is relatively practical and straightforward because it does not require additional devices with an engine. A disadvantage of the pre-treatment is that the applicable pollutants are limited.
3. Combustion enhancement: — An Important Benefit of combustion enhancement is that this technology doesn’t require additional devices outside the engine. A disadvantage of combustion improvement is that optimization, and significant reduction is technically challenging to accomplish Improvement in thermal efficiency of the engine reduces the fuel consumption. Reducing the fuel consumption of Diesel engines by waste heat recovery.
4. After Treatment:- Exhaust gas after treatment is the reduction of pollutants in the exhaust gas. An advantage of the after-treatment is that this process can reduce many pollutants. After Treatment process can apply to many kinds of pollutants. The demerit of the Treatment is that additional devices outside an engine are needed.
5. BioFuels:– Biofuels, which usually are liquid or gas, are made from plants instead of fossil fuels. Diesel Engines use the specified biodiesel fuel. In this process of producing BDF, vegetable oil and animal fats have glycerol.
6. LNG

1. The engines use The Natural evaporated gas known as boil-off gas of LNG as fuel for the engines. The main benefit of LNG usage is that it reduces SOx, NOx, and CO2 emissions mainly. SOx emission is almost zero, while NOx and CO2 will minimize by nearly 80% and 25%, respectively. Nonetheless, a demerit is that a substantial special tank is required to store LNG, which causes problems in terms of expenditure and stock capacity in a ship.
2. Fuel Engines will satisfy the requirement of present and future stringent regulations. Dual fuel engines are very clean engines since these engines use gas as fuel. These engines emit low NOx, particulate matter (PM), CO2, and zero SOx.
3. Gas engines reduce 43% of NOx, 25% of CO2, and 100% of SOx compared to oil. Consequently, dual-fuel engines have many advantages.

Gas-fuel engines will reduce SOx, PM, and CO2 in addition to NOx.

Unlike the ignition of diesel fuel in diesel engines, an ignition source is necessary for combustion in gas engines.

Gas engines use the following methods of ignition.

1. Spark Plug

2. Self Ignition — In this method, a mixture of natural gas and air ignite by the self-ignition of the diesel oil spray.

3. Pre- combustion chamber ignition method by the spark plug.

4. Self Ignition with the spray of diesel oil in the pre-combustion chamber.

Natural gas engines have the disadvantage of Knocking. Knocking causes sharp sound with vibrations. Knocking shockwaves cause damages to the engine material.

Responsive restriction of the air-to-fuel ratio prevents the Knocking-in Dual fuel engines.

In actual operation, output control of power overcomes the Knocking. It is possible in the dual-fuel engine to change over the process from diesel and gas mode internally.

Nevertheless, a few problems and difficulties persist during a change in a property of gas, Due to the presence of low methane number in gas causing knocking.

Options of oil are also tricky due to the difference in properties of Diesel oil and gas. Generally, Marine fuel oil with a sulfur content of 3.5% uses a lubricating oil with a high total base number (TBN) of 30e40 mg(KOH)/g. To improve the performance of both gas and diesel engines development of proper lubrication is essential.

A natural gas fuel with a sulfur content is 0% uses lubricating oil with a low TBN of w5 mg(KOH)/g.

Indian Emission Standards

Conclusion (Emission from Diesel Engines)

I hope the post on Emission from diesel Engines has been useful to readers.

Good Luck!