The Basic Concept of Single-Train Plants

The earlier plants operated at deficit, and needed an auxiliary boiler, which was integrated in the flue gas duct. Auxiliary burners in tunnels or flue gas duet were additionally used in some instances. This situation was partially caused by inadequate waste heat recovery and low efficiency in some energy consumers. Typically, the furnace flue gas was discharged in the stack at rather high temperature because there was no air preheating and too much of the reaction heat in the synthesis loop was rejected to the cooling media (water or air). In addition, efficiency of the mechanical drivers was low and the heat demand for regenerating the solvent from the C02 removal unit (at 

The first generation of the single-train steam reforming plants is discussed in [426], [1007]-[1012], and the required catalysts are reviewed in [633], [1013] -[1014], A survey of the development of the steam reforming concept through 1972 can be found in [1015]. Other references which cover the development of the steam reforming before the introduction of the single-train concept (1940 to 1960) can be found in [402 p. 276]. 

The new plant concept had a triumphant success story. By 1969, 30 new Kellogg large single-train plants with capacities of 1000 t/d or more were in operation, and other contractors were offering similar concepts. 

The decrease in energy consumption compared to the older technology was dramatic, and with the low gas prices at that time it is understandable that greater emphasis was placed on low investment cost, although there was a considerable potential for further reducing the energy consumption. 

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