Fuel cell system including an ammonia remover and method of operating the same

A fuel cell system comprising:

• a reformer that generates a hydrogen-containing gas by using a raw material;
• a fuel cell that generates electric power by using the hydrogen-containing gas;
• an ammonia remover that removes ammonia from the hydrogen-containing gas generated in the reformer before the hydrogen-containing gas is supplied to the fuel cell;
• a fluid passage that allows space in an upper part of the ammonia remover to be in communication with an atmosphere;
• an on-off valve that is provided on the fluid passage and allows and blocks the communication between the space in the upper part of the ammonia remover and the atmosphere;
• and
• a controller including a processor and a memory storing a program,
• wherein the program, when executed by the processor, causes the controller to perform operations including:
• opening the on-off valve in at least one of a water draining process and a water loading process of the ammonia remover.