1. A hydrogen production apparatus comprising a desulfurizer that desulfurizes a source gas, a reformer that heats the desulfurized source gas in a state mixed with steam with a heater and obtains a reformed gas, a CO transformer that causes carbon monoxide in the reformed gas to react with steam and obtains a transformed gas, and a hydrogen purification unit that separates impurities other than hydrogen from the transformed gas after processing by the CO transformer to purify hydrogen gas, further comprising:a gas flow path that allows gas comprising at least one of the source gas, the desulfurized source gas, the reformed gas, the transformed gas, and/or the hydrogen gas to flow to the desulfurizer, the reformer, the CO transformer, and/or the hydrogen purification unit, and a pressure feed configured to cause the gas to flow in the gas flow path,
a controller programmed or configured to perform, in order, a hydrogen purification operation for driving the heater and the pressure feed to supply the gas to the gas flow path, and a stopping operation configured to stop operation of the heater and the pressure feed, and
a throttle unit in a return path that returns and circulates the gas while bypassing the hydrogen purification unit in a closed circulation circuit, the throttle unit configured to switch between a throttled state in which a first flow path resistance is set and a throttle released state in which a second flow path resistance is set, wherein the second flow path resistance is smaller than the first flow path resistance,
wherein the closed circulation circuit that returns and circulates the gas by the pressure feed in an order of the desulfurizer, the reformer, and then the CO transformer while bypassing the hydrogen purification unit, is provided in the gas flow path, and a purge gas supply path is provided where a purge gas is supplied to an upstream side of the pressure feed in the gas flow path,
wherein the controller, prior to the stopping operation, is programmed or configured to perform a purging step of replacing the gas within the gas flow path with the purge gas, and filling the purge gas into the gas flow path,
wherein the controller, in a start-up operation in which the heater is operated to increase the temperature of the gas within the gas flow path, which is performed prior to the hydrogen purification operation, is programmed or configured to perform a pressure increasing step of supplying the purge gas from the purge gas supply path to the closed circulation circuit, and increasing the pressure within the closed circulation circuit while operating the pressure feed, and subsequently to perform a temperature increasing step for operating the pressure feed and the heater and increasing the temperature, and
wherein the controller is programmed or configured to perform the pressure increasing step with the throttle unit switched to the throttled state, and to perform the temperature increasing step with the throttle unit switched to the throttle released state.