Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Electrical Power and Machines

As the world is seeking to use a clean fuel to power up engines, natural gas is one of the most important candidates in this area. In order to use natural gas for residential and industrial purposes, the gas pressure needs to be reduced to pressure that is more convenient for these purposes using Pressure Reduction Stations (PRS). The ordinary PRS using throttling valves to achieve the required pressure drop. There is energy contained in the pressure of the high-pressure gas in the form of enthalpy.The conventional pressure reduction devices used in pressure reduction stations waste this energy.In order to save this energy a turbo expander is used in the PRS which is used to drop the pressure of the gas and drives a generator to produce electricity but this process causes a larger temperature drop. This temperature drop could cause ethane in the gas to condense after expansion or frost problems surrounding the pipe system. To avoid this cooling problem the gas needs to be preheated. Currently, the gas-fired boiler is used and the hybrid turbo expander and fuel cell system is a new approach to this problem. A fuel cell is used to preheat the gas before it enters the turbo expander, and it helps to provide a low range of electrical power

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