Another development of the Lurgi dry-bottom gasifier was the high-pressure Ruhr 100 gasifier which was designed for operation at 100 bar. Apart from its high - pressure capability, the reactor contained a number of other new features. It had two coal lock hoppers, which halves the lock gas losses by half by operating alternately. This was implemented to counter the rise in such losses, which accompanies the rise in operating pressure. It had the additional effect of simplifying the drive arrangement for the stirrer, which could now be mounted centrally. Another new feature was the addition of a second gas tapping at an intermediate level between the gasification and devolatilization zones. Not all the gas volume is required to achieve devolatilization of the feed, so the excess is drawn off from the bed as “clear gas.” The measured compositions of the carbonization gas containing the volatiles and the clear gas are given in Table 5-5.
A 240 t/d pilot plant was started up in 1979. By September 1981 many of the most important goals of the tests had already been confirmed. Increasing the pressure from 25 bar to 95 bar, approximately doubled the throughput of the reactor. The pressure increase also increased the methane production from about 9 mol% in the product gas to 16mol% (Lohmann and Langhoff 1982).