PEM water electrolysis for oxygen generation method and apparatus

摘要

A PEM based water electrolysis stack consists of a number of cells connected in series by using interconnects. Water and electrical power (power supply) are the external inputs to the stack. Water supplied to the oxygen electrodes through flow fields in interconnects is dissociated into oxygen and protons. The protons are transported through the polymer membrane to the hydrogen electrodes, where they combine with electrons to form hydrogen gas. If the electrolysis stack is required to be used exclusively as an oxygen generator, the hydrogen gas generated would have to be disposed off safely. The disposal of hydrogen would lead to a number of system and safety related issues, resulting in the limited application of the device as an oxygen generator. Hydrogen can be combusted to produce heat or better disposed off in a separate fuel cell unit which will supply electricity generated, to the electrolysis stack to reduce power input requirements. This however, will add to system complexity, cost and efficiency loss. The present invention provides an improved method and a simple system for the production of oxygen, and internal utilisation of hydrogen (within the cell / stack) that also reduces the power consumption.