EMISSION CONTROL TECHNOLOGY

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EMISSION CONTROL TECHNOLOGY

• FOR INTERNAL COMBUSTION ENGINES

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INTRODUCTION

• INTERNAL COMBUSTION ENGINES ARE USED IN A VARIETY
  OF STATIONARY APPLICATIONS RANGING FROM POWER
  GENERATION TO INERT GAS PRODUCTION.
• BOTH SPARK AND COMP. ENGINES CAN BE FOUND.
• A VARIETY OF FUELS CAN BE USED FOR I.C.ENGINES.
• THE OPERATION OF I.C ENGINES RESULTS IN THE
  ENISSION OF HYDROCARBONS,CO,NOX,, PARTICULATE
  MATTER.

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TECHNIQUES USED TO CONTROL

• CATALYST CONTROL TECHNOLOGY-
• PRINCIPLE- USED FOR CONTROLLING THE GASEOUS
  EMISSION OF A STATIONARY I.C. ENGINES THE
  CATALYST CAUSES CHEMICAL REACTIONS WITHOUT BEING
  CHANGED OR CONSUMED. CATALYST TRANSFORM
  POLLUTANTS INTO HARMLESS GASES.

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SELECTIVE CATALYTIC REDUCTION

• INTRODUCING A REDUCING AGENTS SUCH AS
  AMMONIA,UREA,MAKES THE NECESSARY CHEMICAL
  REACTIONS POSSIBLE.
• THE REACTIONS ARE-
• 4NO4NH3O2--? 4N26H2O
• 2NO4NH32O2--? 3N26H2O

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OXIDATION CATALYSTS

• OXIDATION CATALYSTS CONTAIN PRECIOUS METALS
  IMPREGNATED INTO A HIGH GEOMATRIC SURFACE AREA
  CARRIER AND ARE PLACED IN THE EXHAUST STREAM THEY
  ARE VERY EFFECTIVE IN CONTROLLING COHYDROCARBON
  EMISSION.

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CATALYTIC CONVERTER
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WORKING

• HELP IN REDUCING EMISSIONS
• BY CONTROLLING EXHAUST BEFORE IT LEAVES THE
  ENGINE.
• BY CONTROLLING THE AIR TO FUEL RATIO(IDEAL RATIO
  14.71 )

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HOW REDUCE POLLUTION

• Most modern cars are equipped with three-way
  catalytic converters. "Three-way" refers to the
  three regulated emissions it helps to reduce --
  carbon monoxide, VOCs and NOx molecules. The
  converter uses two different types of catalysts,
  a reduction catalyst and an oxidation catalyst.
  Both types consist of a ceramic structure coated
  with a metal catalyst, usually platinum, rhodium
  and/or palladium. The idea is to create a
  structure that exposes the maximum surface area
  of catalyst to the exhaust stream, while also
  minimizing the amount of catalyst required (they
  are very expensive).

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DIAGRAMS
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TYPES

• There are two main types of structures used in
  catalytic converters -- honeycomb and ceramic
  beads. Most cars today use a honeycomb structure.

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TYPE 1

• The Reduction CatalystThe reduction catalyst is
  the first stage of the catalytic converter. It
  uses platinum and rhodium to help reduce the NOx
  emissions. When an NO or NO2 molecule contacts
  the catalyst, the catalyst rips the nitrogen atom
  out of the molecule and holds on to it, freeing
  the oxygen in the form of O2. The nitrogen atoms
  bond with other nitrogen atoms that are also
  stuck to the catalyst, forming N2. For example
• 2NO gt N2 O2 or 2NO2 gt N2 2O2

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TYPE2

• The Oxidization CatalystThe oxidation catalyst
  is the second stage of the catalytic converter.
  It reduces the unburned hydrocarbons and carbon
  monoxide by burning (oxidizing) them over a
  platinum and palladium catalyst. This catalyst
  aids the reaction of the CO and hydrocarbons with
  the remaining oxygen in the exhaust gas. For
  example
• 2CO O2 gt 2CO2

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CONTROL SYSTEM

• The third stage is a control system that monitors
  the exhaust stream, and uses this information to
  control the fuel injection system. There is an
  oxygen sensor mounted upstream of the catalytic
  converter, meaning it is closer to the engine
  than the converter is. This sensor tells the
  engine computer how much oxygen is in the
  exhaust. The engine computer can increase or
  decrease the amount of oxygen in the exhaust by
  adjusting the air-to-fuel ratio. This control
  scheme allows the engine computer to make sure
  that the engine is running at close to the
  stoichiometric point, and also to make sure that
  there is enough oxygen in the exhaust to allow
  the oxidization catalyst to burn the unburned
  hydrocarbons and CO.

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THANKS