| abstract |
Synthetic fuels are produced from synthesis gas in a four-stage reactor system with a single recycle loop providing the requisite thermal capacity to moderate the high heat release of the reactions and to provide the reactants and reaction environments for the efficient operation of the process. The first stage converts a portion of the synthesis gas to methanol, the second stage converts the methanol to dimethylether, the third stage converts the methanol and dimethylether to fuel and the fourth stage converts the high melting point component, durene, and other low volatility aromatic components such as tri- and tetra-methylbenzenes to high octane branched paraffins. The four-stage catalyst used for hydrotreating is resistant to CO poisoning. The reactions i produce water as a side product that is carried through to a high pressure separator after the fourth stage. The streams from the separator are a liquid fuel stream, a water stream and a gaseous stream that contains light hydrocarbon gases and the unreacted synthesis gas. The larger part of this gas stream is recycled to the inlet of the first stage and mixed with the fresh synthesis gas stream. Alternatively, the fresh synthetic gas stream is mixed with the product of the second stage. The smaller part of the gas stream from the separator is sent to hydrocarbon recovery and to fuel gas used for providing preheat of various streams. The liquid fuel is sent for blending into fuel products, such as gasoline, jet fuel, or diesel, and the water stream can be sent, for example, to the synthesis gas producing plant for steam generation. |