The fundamental importance of carbon in determining
the mechanical properties of steel, special attention has been devoted to
those controlled atmosphere processes that are require to control carbon
exchange between the furnace atmosphere and work being treated.
The endothermic gas yields a potential between 0.7 to 0.9 which corresponds
to the surface carbon content aimed at in the majority of processes.
Endothermic atmospheres are used principally in the heat treatment of carbon
steels and may be slightly carburizing to low carbon steels. Endothermic gas
is produced by the reaction of an air-gas mixture ranging from 25 to 40% of
perfect combustion. It is necessary to supply external heat in the
endothermic reaction. The process is based on single catalytic cracking of
LPG or natural gas with accompanying admission of air at such a rate that
the product gas after cracking contains only CO, H
2, N
2
and traces of CO
2 and moisture.
- CO : 28 to 30%
- H2 : 20 to 25%
- CO2 : 0.1 to 0.5%
- N2 : Balance
Our endothermic gas generator consist of a mixer unit, cracking retort, gas
cooler and control panel. All equipments are accommodated in a single
compact unit. The reaction takes place in presence of high activity catalyst
at a working temperature around 1050
oC. Heating of the retort is
affected electrically by heating elements around the retort.
- Feed Stock : LPG or Natural Gas.
- Capacities : 5 NM3/hr to 100 NM3/hr packaged
unit.
Exo-gas (lean ratio) : These atmospheres
ranging from 90 % to 98 5 of perfect combustion have the following
composition :
- CO2 : 11 to 13%
- CO : 0. 5 to 1. 5%
- H2 : 0. 5 to 2%
- N2 : Balance
These are normally used for bright annealing of copper, scale-free
annealing of brass and similar operation on non-ferrous metals.
Exo-gas (rich ratio) : The protective gas rich in CO and H
2
is known as rich exo gas and is generated within 55% to 90% of perfect
combustion, the gas composition will be:
- CO2 : 5 to 6%
- CO : 10 to 12%
- H2 : 11 to 13%
- N2 : balance
The composition of atmosphere gas depends on composition of fuel also. The
presence of reducing constituents CO & H
2 will effectively
prevent the oxidation of many metals. However, with the presence of CO
2,
the atmosphere becomes de-carburizing in character.
Therefore we offer following type of exo-gas generator :
Raw Exo - Gas Type : Where the products of combustion are directly
used as. Protective gas.
Partially Dry Exo - Gas Type : Certain applications require only
partial removal of moisture to prevent oxidation and de-carburization. In
these, the gas are passed through a refrigeration unit to reduce the dew
point to around plus 5
oC.
Perfectly Dry Exo - Gas Type : Wherever materials call for moisture
free gas generator is followed by a refrigeration unit and a packaged drier.
Here the dew point of the product gas is reduced to around minus 40
oC.
Fuel : Natural Gas, LPG, Kerosene, Diesel.
Capacities : 10 nm
3/hr to 1000 nm
3/hr in
various standard sizes.
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