Steam generator for fuel cell system

A method of reducing pressure pulsations in a steam generator during steam generation, the steam generator comprising a heat exchanger with at least one internal heat exchange surface;

• a water inflow pipe and a fuel inflow pipe;
• and a dripper head comprising a flow passageway fluidly connected to the water inflow pipe, which dripper head extends inside the heat exchanger above the heat exchange surface for feeding water droplets down onto the heat exchange surface for conversion into steam;
• wherein:
• the dripper head comprises a plurality of outlet holes spaced along the length of the flow passageway;
• between adjacent outlet holes the dripper head has a stepped profile on at least its underside, when viewed in cross-section, the method comprising adjusting the flow rate of the water to a selected flow rate whereby the stepped profile prevents droplets from adjacent holes coalescing;
• each outlet hole being segregated from an adjacent outlet hole by at least one baffle that projects outwardly relative to the outlet hole, the baffle extending at least partially around the circumference or periphery of the dripper head;
• and
• the steam generator combines the fuel with the steam inside the steam generator during use.

A method of operating a steam generator for a fuel cell system, the steam generator comprising:

• a heat exchanger with at least one internal heat exchange surface,
• a water inflow pipe and a fuel inflow pipe,
• a dripper head comprising a flow passageway fluidly connected to the water inflow pipe, which dripper head extends inside the heat exchanger above the heat exchange surface for feeding water down onto the heat exchange surface for conversion into steam;
• wherein the dripper head comprises a plurality of outlet holes spaced along the length of the flow passageway, between adjacent outlet holes the dripper head has a stepped profile on at least its underside, when viewed in cross-section, to prevent droplets from adjacent holes coalescing, each outlet hole being segregated from an adjacent outlet hole by at least one baffle that projects outwardly relative to the outlet hole, the baffle extending at least partially around the circumference or periphery of the dripper head;
• the method comprising:
• feeding water through the water inflow pipe to the dripper head;
• dripping the water from the dripper head, via the outlet holes, as water droplets, rather than steam or a spray, the water droplets dripping onto the heat exchange surface for conversion into steam;
• and
• the steam generator combining the fuel with the steam inside the steam generator during use.