Abstract: A process for operating a system for water vapor reforming of methanol includes a mixture preparation step for preparing a water vapor/methanol mixture from water and methanol, which mixture is subsequently introduced into a reforming reactor in a quantity which depends on the load condition of the system. According to the invention, the water vapor/methanol mixture ratio of the water vapor/methanol mixture introduced into the reforming reactor is maintained at a predeterminable desired value unaffected by short-term load changing operations, to avoid undesirable short-term increases of the CO-concentration in the reformate.

Abstract: A valve with a Laval nozzle, a valve needle movable axially in the Laval nozzle, and an inlet chamber which receives the valve needle foot, in which chamber a radially extended inlet opening terminates. The inlet chamber is separated axially from the inlet plane of the Laval nozzle by a flow channel located therebetween. The inlet chamber is delimited by the valve needle on one side and by one of the valve needle housing sections surrounding the valve needle on the other side. This valve can be used in particular as a metering valve for metering a process gas for a reaction process in a motor vehicle operated by a fuel cell.