Hydrogen-carbon monoxide ratio

Fresh feed that has the proper hydrogen carbon monoxide ratio (i.e., slightly above the 3 1 minimum stoichiometric ratio) is mixed with recycle gas and sent through a heat exchanger and into the first catalyst bed, Stage I. The space velocity in Stage I is controlled so that all of the carbon monoxide fed to it is completely converted. The inlet gases are... 

Solution. The feed consists of a 2 1 molar ratio of hydrogen-to-carbon monoxide, the same ratio in which they react therefore the hydrogen-carbon monoxide ratio remains constant throughout the process. Thus, it is necessary to calculate the flow rates of only one of the reactants carbon monoxide flow rates are calculated here. The hydrogen flow rate in any stream is twice that of carbon monoxide. Perfect separation between reactants and products is assumed. 

However, if electrolysis of water were used to provide oxygen for the gasifier the hydrogen produced at the same time would correct the hydrogen/carbon monoxide ratio. 

The hydrogen/carbon monoxide ratio is nearly ideal for the Fischer-Tropsch stage. However, extra oxygen is needed and the high reaction temperatures lead to... 

Longer chained hydrocarbon formation is much lower than expected. This is presumably because of the high hydrogen. -carbon monoxide ratio of the feed gas and because of the high pressure. Bond (1) cites both these conditions as favoring hydrogenolysis. 

In practice, the Fischer-Tropsch reaction is carried out at temperatures of 200°C-350°C (390°F-660°F) and at pressures of 75-4000 psi. The hydrogen/carbon monoxide ratio is usually 2.2 1 or 2.5 1. Since up to three volumes of hydrogen may be required to achieve the next stage of the liquids production, the synthesis gas must then be converted by means of the water-gas shift reaction to the desired level of hydrogen ... 

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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