Refineries, hydrogen separation

Downstream of the reactors and the hydrogen separator, the product is fed to one or more fractionating columns, where it is split into several streams. If just the butanes and lighter gases are removed, the remaining stream is generally called reformate. But in those refineries where benzene is recovered, to... 

FIGURE 13 Hydrogen separation applications in the refinery. [From S. Leeper etal. (1984). Report No. EGG-2282, EG G Idaho, Inc. (Report to U.S. Department of Energy), and D. L. MacLean etal. (1983). Hydrocarbon Processing 62, 47-51.]... 

There is a recent trend in refineries away from the first option and toward the second, because of the falling cost of hydrogen separation from gas mixtures via pressure-swing absorption. If the C02 from refinery production of hydrogen... 

Carbon dioxide-methane separation Solvent vapor recovery Hydrogen and carbon dioxide recovery from steam-methane reformer off-gas Hydrogen recovery from refinery off-gas Carbon monoxide-hydrogen separation Alcohol dehydration Production of ammonia synthesis gas Normal-isoparaffin separation Ozone enrichment... 

Smith, R., E. A. Petela, 1991-1992, Waste minimisation in process industries. The Chemical Engineer (UK), ibid. 1. The problem, 24-25, Oct. 1991, ibid. 2. Reactors. 17-23, Dec. 1991, ibid 3. Separation and recycle systems, 24-28 Febr. 1992, ibid 4. Process operations, 21-23, April 1992, ibid 5. Utility waste, 32-35, July, 1992 Towler, G. P., R. Mann, A. J. Serriere, C. M. D. Gabaude, 1996, Refinery hydrogen management cost analysis of chemically-integrated facilities, Ind. Eng. Chem. Res., 35 (78), 2378-2388... 

Based on existing technology, a refinery hydrogen unit, using crude oil as a feedstock and a rated output of IOOMW-H2, has a capital cost of 50 million, or an overnight capital cost of approximately 500.5 /kW-H2 (CONCAWE 1999). Based on a thermal efficiency of 36.8%, the crude oil input for this facility is estimated at 8.6 million GJ per year, or 3.1 million GJ-H2. The O M costs are difficult to separate from that of the refinery itself. H2 im initially assumes annual O M costs for the hydrogen refinery unit are 4% of the overnight capital costs. 

In many refineries hydrogen upgrading processes, the impurities to be rejected include hydrocarbons that have value significantly above fuel value. This is particularly true for olefin-containing streams. The relative amounts of high-value hydrocarbons and the incremental cost of further separation determine whether by-product recovery is an important parameter to be considered. 

In the past, the available membranes lost a significant fraction of their selectivity when operated at these high temperatures. They also became plasticized by absorbed heavy hydrocarbons in the feed gas. As a consequence, a number of early hydrogen-separation plants installed in refineries had reliability problems. The development of newer polyimide and polyaramide membranes that can safely operate at high temperatures has solved most of these problems and the market for membrane-based hydrogen-recovery processes in refineries is growing. 

Hydrogen and Cariwn Dtradde Productiaa fiom Steam-Methane Refinner OCf Gas Production of Ammonia Synthesis Gas Hydrogen Recovery fiom Refinery Off Gases Methane-Caibon Dioxide Separation fiom Landfill Gas Caihon Monoxide-Hydrogen Separation Normal - Isoparaffin Separation Alcohol Dehydration... 

Membrane Engineering Progress and Potentialities in Cas Separations 301 14.4.1 Case Study Hydrogen Separation in Refineries... 

During the 1970s, considerable research and developmental work was devoted to membranes. Many potential applications were identified, but commercialization was slow. In 1977, Monsanto demonstrated its first full scale membrane separator at Texas City, Texas, in a hydrogen/carbon monoxide ratio adjustment application (Burmaster and Carter, 1983). In 1979, Monsanto commercialized its hollow fiber membrane module as the Prism separator. From 1979 to 1982 Prism separators were evaluated in several refinery hydrogen purification applications (Bollinger et al., 1982). The success of these pilot tests established the commercial viability of gas separation with membranes. The first large scale commercial CO2 membrane separation project was the installation of two membrane separation facilities at the Sacroc tertiary oil recovery project in West Texas in 1983. Up to 80 MMscfd of gas has been processed in these facilities (Parro, 1984). 

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