No hydrogen available for hydrogen production to start up
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What should be done when there is no hydrogen available at the time of starting up the hydrogen production unit? Some of the materials I read mention the use of liquid ammonia, while others suggest using natural gas directly. Could some expert help explain this? When should liquid ammonia be replenished when using it? ； For those that use natural gas directly, what needs to be taken into consideration during operation? Is the process time-consuming?
We have used both liquid ammonia and natural gas; it’s no problem to have catalyst manufacturers provide on-site guidance
Using natural gas is very convenient, and the reduction time is not long either.
Is there any information available on the direct production using natural gas? Please send it to me; thanks in advance
Process principle of ammonia cracking for hydrogen production and reduction conversion catalyst: In the conversion furnace, N2 gas is used to raise the temperature to 350°C at the furnace inlet; then steam is introduced. Liquid ammonia is added to this steam and together they are fed into the conversion furnace. As ammonia is added, the temperature in the furnace gradually rises to 460°C at the inlet and to 750–800°C at the outlet. Ammonia absorbs heat and cracks within the furnace tubes: 2NH3 = N2 + 3H2. As the temperature of the conversion catalyst bed increases, the ammonia cracking reaction becomes more complete. The conversion catalyst uses hydrogen generated by ammonia cracking for reduction reactions: NiO + H2 → Ni + H2O
Ammonia solution decomposition temperature reached! Also, the hydrogen purity under reduction conditions must be met!
In the low-sulfur natural gas steam reforming process, feed can be introduced in a short period of time, with reduction occurring simultaneously during the reaction, with little impact. Once gas is released from the middle and lower sections, it can be reused to produce hydrogen for desulfurization.
Hydrogen production from natural gas and hydrogen production via ammonia decomposition – both technologies are highly mature! It depends on what purpose the hydrogen is intended for; then different hydrogen production methods can be chosen.
Hydrogen can be produced by the thermal cracking of liquid ammonia for reduction purposes
Either of these two methods works; the one we commonly use is natural gas reduction. Steam is supplied at the outlet of the conversion furnace to raise the temperature to 730 degrees Celsius, after which the hydrogenation reactor is disconnected and natural gas is introduced. The flow rate is increased from 1,000 cubic meters per hour to 4,000 cubic meters per hour, while maintaining a hydrogen purity of over 70%. It is observed that the tubes in the conversion furnace change from red to darker in color; they no longer turn red. Since there is no increase in temperature in the middle section of the reactor, this indicates that the reduction process has been successful. In the liquid ammonia method, when the reduction conditions are met, liquid ammonia is added at the inlet of the conversion furnace; the ammonia gas undergoes cracking to produce hydrogen for reduction, with the hydrogen purity being maintained above 70%, and it is sufficient to add liquid ammonia in an indirect manner. When using liquid ammonia, be careful to avoid frostbite.