Patent ID: 6432565
Filing Date: 2002-08-13
Classification: E21B,H01M,Y02E,Y02P

Abstract:
Process of generating electricity from natural gas using a solid oxide fuel cell comprising the steps of:(a) converting at the anode side of the fuel cell the natural gas to hydrogen and carbon monoxide and allowing the cathode and anode reactions to take place to produce a potential difference between anode and cathode wherein an anode off-gas is produced which comprises water and carbon dioxide; (b) removing oxygen-depleted oxidant from the outlet of the cathode side and removing the anode off-gas from the outlet of the anode side; (c) feeding the anode off-gas from the outlet of the anode side of the fuel cell to a ceramic afterburner installation comprising a membrane consisting of a high temperature ceramic oxide having a characteristic of being permeable to oxygen and impermeable to nitrogen, said high temperature ceramic oxide further being an oxygen-ion conductor; (d) partially condensing the anode off-gas and removing water from the anode off-gas to produce a stream rich in carbon dioxide; (e) compressing the stream rich in carbon dioxide to a predetermined pressure; (f) cooling the compressed stream rich in carbon dioxide at least partly by indirect heat exchange with the natural gas stream which is supplied to the fuel cell to obtain an at least partly liquefied stream rich in carbon dioxide; (g) separating uncondensable gas from the at least partly liquefied stream rich in carbon dioxide; and (h) injecting the at least partly liquefied stream rich in carbon dioxide into a receptacle; characterised in that the step (c) of feeding the anode off-gas to the afterburner installation comprises feeding the anode off-gas to the ceramic afterburner installation in which unburned carbon monoxide and hydrogen are combusted, passing an oxidant through said membrane, and then combining said membrane passed oxidant with said unburned carbon monoxide and hydrogen, wherein said combustion occurs without addition of additional nitrogen to the anode off-gas or membrane passed oxidant.