Process and plant for producing hydrogen from ammonia

A plant for production of hydrogen by cracking of ammonia, comprising:

• a multistage cracking apparatus having multiple catalyst beds for catalytic cracking of an ammonia feed gas stream to hydrogen and nitrogen with supply of heat;
• an evaporation apparatus disposed upstream of the cracking apparatus and in which liquid ammonia is heated and evaporated;
• heat exchangers with which the ammonia feed gas is heatable;
• a hydrogen reprocessing unit, wherein a burner system of a tail gas combustion unit for combustion of a tail gas from the hydrogen reprocessing unit is provided in order to provide a flue gas from this tail gas combustion unit as energy source for the cracking reaction;
• a flue gas duct for the flue gas from the tail gas combustion unit;
• and
• multiple heat exchangers disposed in the flue gas duct, where a first of these heat exchangers is provided for heating of the process gas that has exited from a first catalyst bed and has been cooled down by the reaction in the first catalyst bed to a reaction temperature for a second catalyst bed, where a second of these heat exchangers is provided for heating of the process gas that has exited from the second catalyst bed and has been cooled down by the reaction in the second catalyst bed before it enters a third catalyst bed.

A process for producing hydrogen by cracking of ammonia in a multistage cracking apparatus having multiple catalyst beds for catalytic cracking of an ammonia feed gas stream to hydrogen and nitrogen with supply of heat, comprising:

• heating and evaporating liquid ammonia in an evaporation apparatus upstream of the cracking apparatus;
• heating the ammonia feed gas using heat exchangers;
• combusting a tail gas from a hydrogen reprocessing unit using a burner system of a tail gas combustion unit to provide a flue gas from this tail gas combustion unit as energy source for the cracking reaction;
• passing the flue gas through a flue gas duct;
• and
• heating a process gas that exits a first catalyst bed and that has been cooled down by the reaction in the first catalyst bed to a reaction temperature for a second catalyst bed using a first heat exchanger in the flue gas duct and heating a process gas that exits a second catalyst bed and that has been cooled down by the reaction in the second catalyst bed before it enters a third catalyst bed using a second heat exchanger in the flue gas duct.