In this paper two options for H2 production by means of fossil fuels are presented, evaluating their performance when integrated with advanced H2/air cycles. The investigation has been developed with reference to two different schemes, representative both of consolidated technology (combined cycle power plants) and of innovative technology (a new advance mixed cycle, named AMC). The two methods, here considered, to produce H2 are: • coal gasification: it permits transformation of a solid fuel into a gaseous one, by means of partial combustion reactions; • steam-methane reforming: it is the simplest and potentially the most economic method for producing hydrogen in the foreseeable future. These hydrogen production plants require material and energy integrations with the power section, and the best connections must be investigated in order to obtain good overall performance. The main results of the performed investigation are quite variable among the different H2 production options here considered: for example the efficiency value is over 34% for power plants coupled with coal decarbonization system, while it is in a range of 45–48% for power plants coupled with natural gas decarbonization. These differences are similar to those attainable by advanced combined cycle power plants fuelled by natural gas (traditional CC) and coal (IGCC). In other words, the decarbonization of different fossil fuels involves the same efficiency penalty related to the use of different fossil fuel in advanced cycle power plants (from CC to IGCC for example). The CO2 specific emissions depend on the fossil fuel type and the overall efficiency: adopting a removal efficiency of 90% in the CO2 absorption systems, the CO2 emission reduction is 87% and 82% in the coal gasification and in the steam-methane reforming respectively.
Process integration of membrane reactor for steam methane reforming for hydrogen separation with CO2 capture in power production by natural gas combined cycle
