Hydrogen gas production device

1. A hydrogen gas production apparatus comprising:

a vaporizer configured to generate ammonia gas by heating liquid ammonia;

a main thermal decomposition device configured to decompose the ammonia gas generated in the vaporizer, into nitrogen gas and hydrogen gas, by heating the ammonia gas by causing a fuel gas to burn;

a cooler configured to cool a first decomposition gas including the nitrogen gas and the hydrogen gas generated through the decomposition in the main thermal decomposition device; and

a separator configured to separate hydrogen gas from the first decomposition gas having been cooled,

wherein the cooler is configured to cool the first decomposition gas by allowing heat exchange between the liquid ammonia before being introduced into the vaporizer and the first decomposition gas, and

the vaporizer generates ammonia gas by heating the liquid ammonia having undergone the heat exchange in the cooler.

2. The hydrogen gas production apparatus according to claim 1 , further comprising:

a sub thermal decomposition device configured to decompose a portion of the ammonia gas generated in the vaporizer, into nitrogen gas and hydrogen gas, by heating the portion of the ammonia gas; and

a mixer configured to mix a second decomposition gas including the nitrogen gas and the hydrogen gas generated through the decomposition in the sub thermal decomposition device, and another portion of the ammonia gas generated in the vaporizer, to generate the fuel gas, wherein

the main thermal decomposition device heats a remainder of the ammonia gas generated in the vaporizer, by causing the fuel gas to burn together with air.