PRINCIPLE OF OPERATION
Ammonia Cracker gas generator produces mixture of Hydrogen and Nitrogen which is commonly used in Heat treatment furnaces. Ammonia gas from cylinders is passed over a bed of Nickel Catalyst at 850 degree celcius temperatures and cracking takes place into its basic constituents i.e. 75% H2 & 25% N2.
Ammonia cracking reaction is Endothermic and hence it requires heat from outside source. The source is electrically heated type furnace (Rectangular shape) and a Retort made of heat resistant provided inside to hold the catalyst.
PROCESS OF OPERATION
Ammonia gas is supplied from the battery of cylinders at the battery limit of the unit. The liquid ammonia cylinders are kept vertically in a water trench and vapor ammonia gas from the top of the cylinders is supplied to the unit. The vapor Ammonia Pressure is reduced to the required 0.5 kg/cm2 g by pressure regulator. It is then passed through the heat interchanger where ammonia vapor gets pre-heated up and then enters the catalyst tube (i.e. Retort) from top. In retort, it comes in contact with catalyst and gets cracked at high temperature.
The ammonia cracking reaction is endothermic and takes place at approximately at 850 degree celcius temperatures. The heat of reaction is supplied by providing electrical heating elements in the heating chamber. The furnace has temperature controller for automatic temperature control, which controls the reaction temperature.
The cracked ammonia gas coming out from the bottom of the retort at around 850 degree celcius is then passed through the heat inter-changer to pre-heat the un-cracked ammonia feed. Here the cracked gases gets cooled to around 400 degree celcius. For further cooling these gases now passes through a water cooler to bring them to around 40 degree celcius.
In the cracked ammonia outlet line a Rotameter is provided to indicate continuous flow. This Ammonia Cracker can be operated at any capacity from 10 to 100 % rating simply by throttling ammonia feed line valve. Whenever ammonia is not in use, nothing need to be done except closing the feed valve. The temperature of the ammonia cracking furnace is automatically controlled by the temperature controllers. The ammonia cracking plant can be kept in hot condition for days and days. Whenever you wish to restart cracking process, it can be done instantaneously. Whenever plant is to be shut-down for long time, the ammonia cracking furnace can also be shut-down. It takes around 8-hours for Ammonia Cracking Furnace for heat up to reach operating temperature of 850 degree celcius.
PURIFIER
For reducing residual ammonia and to get very dry gas, a Molecular seives based purifier is provided after Ammonia cracking unit. This reduces ammonia down to 1-ppm level and dries gas up to (-) 80 degree celcius dew point.
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Without Purifie |
With Purifie |
Hydrogen |
75% |
75% |
Nitrogen |
25% |
25% |
Oxygen |
Nil |
Nil |
Residual Ammonia |
100 PPM(max) |
1 PPM (max) |
Dew Point |
(-) 30 0C |
(-) 80 0C |
CAPACITIES OFFERED
3 Nm3/hr to 300 Nm3/hr.
SALIENT FEATURES
• Fully automatic, skid mounted units.
• Rectangular furnace has hinged type door for easy inspection and maintenance.
• Power consumption is low as 0.5 KW per NM3 of gas generated.
• Skin temperature as low as 35 degree celcius above ambient.
• High turn down ratio.
• Very safe and proven design, No operator is required.
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