Mvs Engineering Limited

EXO-gas generators produces protective atmosphere for Heat Treatment furnaces. Lean Exo-gas or Rich Exo-gas is produced simply by changing the air to fuel ratio in burner.

Lean Exo-Gas principle: Lean Exo-gas is produced by burning of fuels at slightly lower sub-stoichiometric combustion air to fuel ratio. This Exo-gas is lean in CO + H2 content. Lean Exo-gas generators are suitable for non-ferrous metals heat treatment.

Rich Exo-Gas principle: Rich Exo-gas is produced by burning of fuel at high sub-stoichoimetric combustion of air to fuel ratio. So the Exo-gas produced is rich in CO + H2 content. Rich Exo-gas generators are used for heat treatment of steel and also brazing and annealing applications.

• Dew Point: By providing a Refrigerated dryer after Gas generator dew point of (+) 5°C is achieved. For (-) 60°C dew point, a Molecular Sieves dryer is provided.

• Burner: These gas generators are fitted with a specially designed Swirl Flame burner which gives soot free combustion and oxygen free Exo-gas even under sub-stoichiometric conditions. Burner is ignited by spark plug and flame is continuously monitored by UV-flame scanner.

• Safety Interlocks: Fuel supply to burner stops automatically and gas generator shuts down safely giving audio-visual alarm due to any problem like-low combustion air pressure, flame failure, low water flow or low fuel pressure.

Fuel: The following fuels can be used in these Exo-gas generators:

• Natural Gas
• LPG
• Propane Gas
  

Endo-gas (endothermic gas) generators produce Endothermic gas (mixture of CO, CO2, N2 and H2) by reaction of air and fuel on Nickel catalyst at 1050°C temperature.

Endothermic Gas Generation principle: Endothermic process requires external heat which is provided by electrical heaters or fuel burning around the retort. Retort is made of heat resistant alloy suitable for 1050°C temperature. Due to cracking of fuel, some carbon deposits on catalyst, which is burnt-off every 15-days running by regeneration process which regains catalyst activity.

 

Lifespan of major components:

• Life of retort is around 2-years.
• Catalyst life is around 2-years.
  

Fuel:

The following fuels can be used in these generators:

• Natural Gas
• LPG
• Propane Gas
  

Kerosene and Diesel fuels are not suitable for Endo-gas generation.

 

Industrial Uses:
Endo-gas generators find use in:

• Gas carburizing
• Carbon restoration in steel
• Carbo-nitriding
• Hardening / Annealing
• High temperature Brazing
• Sintering
• Reduction of metal oxides

Use of furnace atmospheres based on Methanol cracking has become widely acceptable as alternative to Endo-gas generators for many applications like carburizing, carbonitriding, annealing and hardening. Here Nitrogen gas is used as a carrier gas which reduces consumption of methanol. Cracking process at temperatures above 750˚C is as under:

• CH3OH=2H2 + CO

Mixture of Nitrogen and Methanol (e.g. methanol 5 liters & Nitrogen 10 NM3) fed into furnace provides gas composition equivalent to Endo-gas as under:

• Carbon Dioxide (CO2) : 0.5% (Max)
• Carbon Monoxide (CO) : 20%
• Hydrogen (H2) : 40%
• Nitrogen (N2) : Balance
• Dew Point : (-) 40°C
  

Nitrogen gas of 99.5% purity from cylinders or from a captive PSA-Nitrogen generator is used. Methanol should be free from moisture for getting low dew point in your furnace.

• Turn Key Supply: We supply "Nitrogen + Methanol" system on turn-key basis. For nitrogen gas generation, we supply a PSA Nitrogen generator and for methanol feeding we provide a methanol feed tank, methanol flow meter and a methanol inline vaporizer.

Applications:
This type of generator is widely used in Heat Treatment furnaces for:

• Carburizing
• Carbo-nitriding
• Annealing
• Hardening