THERMODYNAMIC ANALYSIS AND SYSTEMS DESIGN FOR COGENERATION OF POWER AND HYDROGEN FROM COAL

The concept of cogeneration of power and hydrogen plants is introduced with specific regard to the coal. coal requires steam to be converted to hydrogen, while coal fed powerplants usually discharge heat by condensing steam. Moreover, hydrogen can be burned with oxygen to produce steam and to generate power in high-temperature steam cycles. These considerations suggest that an integration of the processes could result in a very high efficiency of conversion . Several layouts with an integrated coal gasifier hydrogen production and a powerplant section have been modelled using a computer code (ASPEN PLUSTM). The gasifier is an atmospheric one and its integration with a partially counterpressure steam powerplant allows to reduce the losses at the condenser. The steam discharged from the intermediate pressure turbine is reheated and fed to the gasifier. The efficiency of the power plant is not high when considering the heat supplied, but a large amount of the heat discharged is utilised by the coal gasifier. The global efficiency is very high (more than 75%) and the cogeneration ratio (up to 11%) is suitable to meet a real demand of fuel and power, when considering the contribution of other power generation (i.e.: renewable sources).