Autothermal ammonia cracker

A method of autothermally cracking ammonia with air or oxygen, comprising the steps of:

• providing a counterflow heat exchanger having one or more inlets in gas flow communication with one or more incoming flow channels, one or more outgoing flow channels in gas flow communication with an outlet, and a turnaround region in gas flow communication with the incoming and outgoing flow channels;
• flowing gaseous ammonia into an inlet of the heat exchanger;
• flowing an oxygen-containing gas mixture into an inlet of the heat exchanger;
• preheating the ammonia within one or more of the incoming flow channels;
• preheating the oxygen-containing gas mixture within one or more of the incoming flow channels;
• combusting the preheated ammonia and the preheated oxygen-containing gas mixture within the heat exchanger at a gas temperature that is higher than 1400° C., or at a gas temperature that is higher than 1300° C. in combination with a gas pressure that is higher than 1 bar, or at a gas temperature that is higher than 1200° C. in combination with a gas pressure that is higher than 10 bars, thereby forming a hydrogen-containing gas mixture from the ammonia and from the oxygen-containing gas mixture;
• cooling the hydrogen-containing gas mixture within one or more of the outgoing flow channels;
• and
• flowing the hydrogen-containing gas mixture out of the outlet of the heat exchanger;
• wherein the heat exchanger performs the cooling of the hydrogen-containing gas mixture in conjunction with the preheating of the next incoming ammonia and also in conjunction with the preheating of the next incoming oxygen-containing gas mixture.

A method of autothermally cracking ammonia with an oxygen-containing gas mixture, comprising the steps of:

• providing a counterflow heat exchanger having flow channels for separately preheating gaseous ammonia and an oxygen-containing gas mixture in conjunction with cooling of reaction products which are formed from the ammonia and from the oxygen-containing gas mixture;
• separately preheating the ammonia and the oxygen-containing gas mixture by the heat exchanger;
• decomposing some or all of the preheated ammonia within the heat exchanger, thereby forming a hydrogen-containing gas mixture from at least a portion of the ammonia;
• burning a portion of the preheated ammonia or a portion of the hydrogen-containing gas mixture with the preheated oxygen-containing gas mixture within the heat exchanger, thereby forming an exhaust gas and releasing heat for the decomposition of the ammonia;
• and
• cooling the exhaust gas and the hydrogen-containing gas mixture by the heat exchanger;
• wherein the heat exchanger performs the cooling of the exhaust gas and the hydrogen-containing gas mixture in conjunction with the preheating of the next incoming ammonia and next incoming oxygen-containing gas mixture.

A method of starting an autothermal ammonia cracker, comprising the steps of:

• providing a counterflow heat exchanger having a first inlet in gas flow communication with a first set of one or more incoming flow channels, a second inlet in gas flow communication with a second set of one or more incoming flow channels, wherein the first and second inlets are separate, a set of one or more outgoing flow channels in gas flow communication with an outlet, and a turnaround region or combustor in gas flow communication with the incoming and outgoing flow channels;
• flowing a flammable starting mixture into the heat exchanger in conjunction with a starting period, wherein the starting mixture comprises a fuel component and an oxidizer component, separate from the fuel component;
• flowing the fuel component into the first inlet;
• flowing the oxidizer component into the second inlet;
• separately flowing the fuel component and the oxidizer component through the incoming flow channels and into the turnaround region or combustor;
• combusting the starting mixture within or downstream of the turnaround region or combustor, thereby releasing heat for raising a temperature of the heat exchanger.