Ammonia cracker

Hydrogen is indispensable for the bright hardening or annealing of metals. But, viewed from the standpoint of safety, hydrogen gas is by no means an advantageous atmosphere. Dissociated ammonia atmosphere or forming gas is the only furnace atmosphere that can make up the demerits of hydrogen and function nearly 100% as if it were hydrogen gas. There are cases where forming gas cannot replace pure hydrogen, but such cases are very rare. For almost all applications involved, forming gas atmosphere will answer the purpose.

An ammonia cracker, NH₃-cracker or hydrogen generator is used for the production of forming gas. Hydrogen and Nitrogen are generated in a cost effective way in a volume ratio of 3 : 1 or in a weight ratio of 14 : 3. The NH₃ is coming from bottles or from an ammonia tank.

The dissociation of ammonia gas NH₃ takes place at a temperature of around 920°C in the presence of a special catalyst in an electrically heated furnace.

2 NH₃ → 3H₂+ N₂

Using a heat exchanger for pre-heating the incoming gas by the hot cracked gas from the furnace helps saving energy.

Applications

The forming gas is used in conveyor furnaces and in tube furnaces for anneal processes in a reducing atmosphere for brazing, sintering, deoxidation, and nitrization.