One of the pictures shows the process route, which (a) enables one to understand what the pictures mean and (b) describes a technology that is now lost. The photograph shows one of the liquid phase “stalls” at Billingham. Liquid phase, in this case, means that the oil stayed as a liquid.
Each stall contained a set of three reactors in which hydrogen reacted with a coal oil slurry, whereby part of the coal formed more oil. The oil was separated off from the unreacted coal, and sent round to a distillation column. The lightest fraction from the distillation column was similar to petrol and mixed with the output from the second stage of the process,
In the second stage, the fraction of the oil, from the distillation column, with an intermediate boiling point was sent to the two vapour phase hydrogenation reactors. More petrol was made. It will be apparent that the whole process was very complex and can only be understood by working through the diagram.
Images and details courtesy of Fred Starr.