A novel approach for treatment of CO_2 from fossil fired power plants. Part B: The energy suitability of integrated tri-reforming power plants (ITRPPs) for methanol production

摘要

In Part A of this two-paper work, a novel approach for treatment of CO_2 from fossil fired power plants was studied. This approach consists of flue gases utilization as co-reactants in a catalytic process, the tri-reforming process, to generate a synthesis gas suitable in chemical industries for production of chemicals (methanol, DME, ammonia and urea, etc.). In particular, the further conversion of syngas to a transportation fuel, such as methanol, is an attractive solution to introduce near zero-emission technologies (i.e. fuel cells) in vehicular applications. In fact, the methanol can be used in DMFC (Direct Methanol Fuel Cell) or as fuel for on-board reforming to produce hydrogen for PEMFC (Proton Exchange Membrane Fuel Cell). Thus, in order to analyze the tri-reforming process, integrated systems, ITRPPs (Integrated Tri-Reforming Power Plants) for co-generation of electrical power and synthesis gas were defined and their performances were investigated. The integrated systems consist of a power island, based on a thermal power plant (a steam turbine power plant, ITRPP-SC, and a gas turbine combined cycle ITRPP-CC), and a methane tri-reforming island. This paper (Part B) focuses on the methanol synthesis process by using the syngas produced by the methane tri-reforming island. Therefore, the ITRPP plant configurations have been modified adding the methanol synthesis island and the performances of these integrated plants, that co-produce electrical power and methanol, have been evaluated. The energy and environmental analysis has been carried out by means of a numerical approach which has allowed to calculate the syngas composition, to define the energy and mass balances and to estimate the CO_2 emissions for each configurations. Furthermore, the conventional technology for methanol generation, based on methane steam reforming with carbon dioxide addition, has been analysed and the performances of integrated systems (ISRPP, Integrated Steam Reforming Power Plant), that consist of a power island with a CO_2 capture unit, the methane reforming island and the methanol synthesis island, have been investigated.rnResults point out that the energy and environmental sustainability of the integrated plants, based on the tri-reforming technology for the co-generation of electrical power and methanol, depends on the flue gases composition. Thus, the tri-reforming process can be considered a promising approach for treatment of CO_2 when the exhausts contain low oxygen concentrations (i.e. flue gases from steam cycle power plant).