With renewed interest in enhanced oil recovery (OR) as existing fields become depleted, there is renewed interest in supplying CO2 for flooding by CO2 recovery from flue gas. This paper examines key design and operating issues and trends for new unit designs which hold the potential for reducing the costs associated with this source of CO2.
In the mid-I980's, when crude oil prices were over $30 per barrel, several plants came on line in West Texas in the U.S. which used 30 wt% MEA with special inhibitors to extract CO2 from boiler flue gas for use in OR. However, when the price of crude oil dropped dramatically, these plants quickly became uneconomic and were scrapped. The then existing pro=s licensors, Dow Chemical and Union Carbide, became less active in promoting these technologies and in 1989 Dow Chemical sold their FT-l process to Fluor Daniel Inc.. Fluor Daniel renamed the technology "ECONAMINE FGSM" and bas since licensed two commercial plants, one 320 te/d plant at Bellingham Massachusetts (U.S.A.) (1989) and also te/d plant for Sumitomo Chemical at Chiba, Japan (1993). Both plants sell CO2 primarily to the food industry. The Bellingham plant, which bas a gas turbine exhaust flue gas source, was constructed by Fluor Daniel. The Sumitomo plant was constructed by Mitsubishi Heavy Industries (MHI) with the flue gas source from a boiler fired by a variety of fuels including heavy fuel oils.
In addition, Fluor Daniel has completed a number ofstudies, several of which involved large-scale plants (1000 teld and larger). These studies were prompted by interest in using the CO2 for OR and to avoid the new carbon tax being imposed in EC countries. In addition, Fluor Daniel designed two pilot plants for Japan which were used by the owners to study the process for greenhouse gas mitigation purposes. The results from the KEPCO pilot plant have been reported in the literature. 1,2 Much of the KEPCO work is applicable to OR applications as will be discussed later in this paper.
Interest in greenhouse gas emission mitigation has spawned a number of processes for capturing .CO2 from boiler stacks (hat differ considerably from capture by chemical solvents. None of these processes are presently offered commercially ant! most will remain in the laboratory study phase at least for the near future. The inherent cost of CO2 capture and subsequent sequestration either in land formations or as clathrates in deep ocean trenches has proven to be expensive for any proposed process. Japan's Central Research Institute of the Electric Power Industry (Criepi, Tokyo) has concluded (hat the economics of CO2 fixation and disposal will not be economical for fossil fuel plants and proposed other alternatives for limiting CO2 emissions.3 The Japanese government has co-funded a number of cooperative studies concerning CO2 capture and sequestration. In Norway, which presently is imposing the highest carbon tax in the EC, studies are underway to develop novel CO2 capture techniques (hat employ chemical solvents using membrane technology in the absorption step.