Hydrogen generator, operating method of hydrogen generator, and fuel cell system

1. A hydrogen generator comprising:

a hydro-desulfurizer configured to remove sulfur compounds from a raw material;

a reformer configured to generate hydrogen-containing gas with use of the raw material that has passed through the hydro-desulfurizer;

a raw material supply device configured to supply the raw material to the reformer;

a recycle flow passage configured to supply a portion of the hydrogen-containing gas discharged from the reformer, to the raw material before the raw material flows into the hydro-desulfurizer;

an on-off valve provided in said recycle flow passage;

a pressure detector located at a position upstream of the on-off valve in the recycle flow passage; and

an abnormality detector configured to detect an abnormal clogging in the recycle flow passage based on a pressure detected by the pressure detector, in a state in which the raw material supply device is supplying the raw material to the reformer, with the on-off valve closed.

2. The hydrogen generator according to claim 1 , wherein the abnormality detector closes the on-off valve in its open state in a state in which the reformer is generating the hydrogen-containing gas and detects an abnormal clogging based on a pressure detected by the pressure detector after the closing of the on-off valve.

3. The hydrogen generator according to claim 1 , wherein the abnormality detector closes the on-off valve in its open state before the reformer starts generation of the hydrogen-containing gas and detects an abnormal clogging based on a pressure detected by the pressure detector after the closing of the on-off valve.

4. The hydrogen generator according to claim 1 , wherein the abnormality detector closes the on-off valve in its open state after the reformer stops generation of the hydrogen-containing gas and detects an abnormal clogging based on a pressure detected by the pressure detector after the closing of the on-off valve.

5. The hydrogen generator according to claim 1 , comprising a throttle section disposed in the recycle flow passage, and wherein the pressure detector is located downstream of the throttle section.

6. The hydrogen generator according to claim 1 , comprising a buffer section in a portion of the recycle flow passage which is located downstream of the on-off valve.

7. The hydrogen generator according to claim 1 , comprising a controller configured to execute a process for relieving an abnormal clogging in the recycle flow passage after the abnormality detector detects the abnormal clogging in the recycle flow passage.

8. The hydrogen generator according to claim 1 , comprising a notification device configured to notify that an abnormal clogging has occurred in the recycle flow passage.

9. The hydrogen generator according to claim 7 , comprising a notification device configured to notify that a process for relieving the clogging in the recycle flow passage is in execution.

10. A fuel cell system comprising:

the hydrogen generator recited in claim 1 ; and

a fuel cell configured to generate electric power using hydrogen-containing gas supplied from the hydrogen generator.

11. A method of operating a hydrogen generator comprising the steps of:

removing sulfur compounds from a raw material by a hydro-desulfurizer;

generating hydrogen-containing gas by a reformer, using the raw material that has passed through the hydro-desulfurizer;

supplying a portion of the hydrogen-containing gas which has been discharged from the reformer, through a recycle flow passage, to the raw material before the raw material flows into the hydro-desulfurizer;

detecting, by a pressure detector, a pressure in a portion of the recycle flow passage which is located upstream of an on-off valve provided in the recycle flow passage; and

detecting an abnormal clogging in the recycle flow passage based on the pressure detected by the pressure detector, in a state in which the raw material is being supplied to the reformer with the on-off valve closed.