(JP9180746-A)      A device has the following items; fuel cells in a stack, a thermal insulating shell, a follow-up of after-burning combustion chamber between the stack and the shell and an auxiliary burner. The follow-up chamber is joined at opposite ends through channels with at least one outlet (4) for exhaust gases. These channels are sealed off by two valves.    A combustion chamber of the auxiliary burner communicates with the channel between the follow-up chamber and the second valve. In a starting phase, the second valve is closed and the first is opened. A pre-reformer for gas treatment is in the shell, joined to a heat exchanger which has a heating channel used by the exhaust gas of the auxiliary burner.    ADVANTAGE -   No damage to cells during start-up phase.    (US5840437-A)      A device has the following items; fuel cells in a stack, a thermal insulating shell, a follow-up of after-burning combustion chamber between the stack and the shell and an auxiliary burner. The follow-up chamber is joined at opposite ends through channels with at least one outlet (4) for exhaust gases. These channels are sealed off by two valves.    A combustion chamber of the auxiliary burner communicates with the channel between the follow-up chamber and the second valve. In a starting phase, the second valve is closed and the first is opened. A pre-reformer for gas treatment is in the shell, joined to a heat exchanger which has a heating channel used by the exhaust gas of the auxiliary burner.    ADVANTAGE -   No damage to cells during start-up phase.    (EP780917-B1)      A device has the following items; fuel cells in a stack, a thermal insulating shell, a follow-up of after-burning combustion chamber between the stack and the shell and an auxiliary burner. The follow-up chamber is joined at opposite ends through channels with at least one outlet (4) for exhaust gases. These channels are sealed off by two valves.    A combustion chamber of the auxiliary burner communicates with the channel between the follow-up chamber and the second valve. In a starting phase, the second valve is closed and the first is opened. A pre-reformer for gas treatment is in the shell, joined to a heat exchanger which has a heating channel used by the exhaust gas of the auxiliary burner.    ADVANTAGE -   No damage to cells during start-up phase.