Environmental Emissions: Industry and Automobiles

DR. MD. EHSAN

CES, BUET, NOV 2009

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Environmental Pollution

“Environmental Pollution” is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms.

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How is Contributing Most to Environmental Pollution ?

The major contribution to the environmental pollution comes from only a few countries. Several countries in the developed world are the leaders in air polluting emissions.

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This includes Gas-borne pollutants discharged into the atmosphere from different man-made or natural sources eg. - Smokestacks of Industrial and Power generation plants, Exhaust from Vehicles, Burnt Gases from Bushfires or Volcanic Irruptions.

Air pollution comes from both natural and man made sources. Though globally man made pollutants from combustion, construction, mining, agriculture and warfare are increasingly significant in the air pollution equation. Motor vehicle emissions are one of the leading causes of air pollution.

Environmental Emissions:

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“Global Warming” due to “Green House Effect” is the consequence of continuous large scale environmental emissions and mainly responsible for gradually increasing the temperature the earth’s atmosphere. World wide this is becoming the highest environmental concern today. The polluting gases that contribute to Global Warming are termed as Green House Gases (GHG).

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Constitution of Industrial Emissions:

Industrial Emissions is a broad term covering many process which involves fossil fuel combustion. This includes - Industry, Residential heating, Transportation (cars, trucks, and airplanes), Power Generation Utilities, and Commercial heating. Fossil fuels include coal, oil, natural gas, and gasoline. Two other processes are also usually included with industrial emissions. The first is the production of cement, which releases large amounts of CO2 as the limestone is prepared. The second item is gas flaring from oil fields.

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Air Quality Index

The Air Quality Index (AQI) is an index (that is, a numerical value or ratio derived from a series of observations) for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The purpose of the AQI is to help you understand what local air quality can mean to your health. To make it easier to understand, the AQI is divided into six categories:

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Industrial Emission Standards : Limits of Pollutants

Substances Sources Units Standard Values

Antimony Any source mg/Nm3 20

Arsenic Any source mg/ Nm3 20

Carbon monoxide Any source mg/ Nm3 or ppm 1000 or 870

Chlorine Any source mg/ Nm3 30

Copper Furnace or smelter mg/Nm3 30

Hydrogen Chloride Any source mg/Nm3 200

Hydrogen Sulphide Any source mg/Nm3 or ppm 140 or 100

Lead Any source mg/Nm3 30

Mercury Any source mg/Nm3 30

Oxides of Nitrogen Boiler / - Coal as fuel mg/Nm3 or ppm 940 or 500

Oxides of nitrogen Boiler / -Others fuel mg/Nm3 or ppm 470 or 250

Particulate Boiler & Furnace / - Coal as fuel

mg/Nm3 400

Particulate Boiler & Furnace / - Others fuel

mg/Nm3 400

Particulate Boiler & Furnace / - Heavy oil as fuel

mg/Nm3 300

Particulate Steel/ Aluminum Manufacturing

mg/Nm3 300

Particulate Other source mg/Nm3 400

Sulfur-di-oxide H2SO4 production mg/Nm3 or ppm 3000 or 500

Sulfuric acid Any source mg/Nm3 or ppm 100 or 25

Xylene Any source mg/Nm3 or ppm 870 or 200

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Ways of Controlling and Mitigating Environmental Emissions

• More Efficient Systems : Better machines or Operating Processes are used. Less fuel needs to be burned, Less Green hours gases would be produced.

• Reduction of Energy Wastage : Using the Energy better, involves loss

minimization after energy being produced.

• Removing Green House Gases : Carbon Capture and Storage (CCS) Technology.

• Use Renewable and Non-Polluting Source More : Technology needs to be further developed and commercialized.

• Recycle Material as much as possible: Reduces energy requirement for new materials.

• Economic Incentives : Efficient energy user must be encouraged by policy.

• Motivation and Awareness : Increasing public awareness through education and incentives.

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Emission from Motorized Vehicles

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Emission from Internal Combustion Engines

Expected Products : CO2 and H2O, as the fuels are hydrocarbons.Undesirable Products : CO, Unburned HC, NOx , PM, SOx , Pb

Major Emission Concerns :SI Engines : CO, Unburned HC, NOx, PbCI Engines : PM, NOx, Unburned HC, SOx

Unburned HC : Major Concern for SI engines.Could be as high as 6000 ppm, 1.5% of fuelConstitutes of fuel itself and partially reacted components.

Causes of Formation : Non-Stoichiometric AF ratios of combustionIncomplete combustion, EGRCrevice volumesValve Overlap

Oil or deposition on combustion chamber wall

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Carbon Monoxide (CO) :Major Concern for SI engines.Could be as high as 5% of exhaust volume.

Causes of Formation : Non-Stoichiometric AF ratios of combustion, Incomplete combustion, EGR

Nitrogen Oxides :Major Concern for both SI and CI engines.Could be as high as 2000 ppmConstitutes of NO and NO2

Causes of Formation : High temperature of combustionAvailability of excess Oxygen at high tempHighest rate at slightly lean mixture (=0.95)

Photo-Chemical Smog : NO2 + Energy from Sunlight NO + O O + O2 O3 (Ground level)

Sulfur Oxides (SOx) :Major Concern for CI engines.Causes of Formation : Sulfur in fuel SI (150-600 ppm), CI (5000 ppm-1%)

LSD (low sulfur diesel), ULSD (Ultra low sulfur diesel < 50ppm)

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Particulate Matter (PM) :

Major Concern for CI engines, may be in SI engines at high loads.High concentration effects the opacity of exhaust (smoke)Constitutes of Carbon Soot Particle, coated with SO3 and Soluble Organic Fractions (SOF) of fuel.

Average mean diameter – 10 m (PM 10), 2.5 m (PM 2.5) Smaller the size more is the health hazard.

Causes of Formation : Near-Stoichiometric AF ratios of combustionPresence of heavy components in the fuelRicher burning at high loads

At higher temperatures : PM but NOX

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Emission Standards :

Emission Standards may vary in different countries. The standards are getting stringent day by day.

EURO stand. CARB stand. FTP stand. EPA stand. Mode stand.

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Emission Measurement : Gas Analyzers

These are instantaneous vehicle emission measuring devices. Typically have Infrared and Electro-Chemical sensors for measurement of gas components.

3-Gas Analyzers : CO2 , CO and HC4-Gas Analyzers : CO2 , CO, HC and remaining Oxygen5-Gas Analyzers : CO2 , CO, HC, remaining Oxygen and NOx

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Emission Control Techniques

Pre-Engine System : Hot Air Intake SystemIn-Engine System : Electronic Fuel Injection, Exhaust Gas Recirculation Post-Engine System : Catalytic Converter, Diesel Particulate Filter

CC : Post Engine Emission Control Device Used for Petrol Vehicles

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Diesel Particulate Filters

DPF : Post Engine Emission Control Device used for Diesel run Vehicles

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Thank You

Let us all work for a better Environment