Process and installation for cogeneration of electrical energy and steam

摘要

The by-product is reduced in hydrogen to a concentration of 5% or less, preferably ca. 2%, to form a mostly methane fuel gas to feed a turbine combustion chamber. At least part of the residual gas (13) left from the reduction process and rich in hydrogen is used to fuel a post-combustion operation at the inlet to the recovery heater. The process uses a gas turbine (3) and a heater (4) recovering heat from the turbine exhaust gases (15) on an industrial site where one unit (1) forms a gaseous by-product (7) containing methane and hydrogen. Part of the residual gas is used to fuel an auxiliary heater (22) producing steam. A small amount of fuel (18,23), e.g. natural gas, is added to the fuel (17,21). The fuel contains 40-60% hydrogen. The reduction of hydrogen comprises treatment of the by-product by selective permeation. The gas turbine is the type with dry chamber combustion and low nitrogen oxide (NOx) production. The by-product contains 20-60% methane, 10-65% hydrogen and other components. The unit producing the by-product is a petrochemical installation, in particular a refinery, and the by-product has a composition of: 30-70% CH4, 10-40% H2, 0-40% C2 and 0-20% other components. The fuel gas has a composition of 40-90% CH4 (preferably 50-90%), 0-5% H2, 0-45% C2 and 0-25% other components. Alternatively, the unit is a steelworks, with the by-product a coking gas with a composition of: 20-30% CH4, 55-65% H2, 2-8% C2, 1-6% N2, 2-10% CO and 0-10% other components. The fuel gas in this case has a composition of 60-70% CH4, 0-5% H2, 5-20% C2, 5-15% N2, 5-15% CO and 0-10% other components. An Independent claim is also included for an apparatus for the above process.