Gasification

The Lurgi Dry Ash Process

The patent for the Lurgi dry ash process, or “coal pressure gasification” as it was originally known (“Vergasung von Braunkohle unter Druck mit Sauerstoff-Wasser - dampf-Gemischen,” or “Gasification of browncoal under pressure with oxygen-steam mixtures”), was granted in 1927. In 1931 Lurgi started to develop, a pressurized version of existing atmospheric producer gas technology, using oxygen as blast, initially for gasification of lignite (Lurgi 1970; Lurgi 1997). The development was made in close cooperation with the Technical University in Berlin under the direc­tion of Professor Rudolf Drawe, one of the fathers of modern gasification. The first commercial application was built in 1936 (Rudolf 1984). In 1944 two large-scale plants were in operation in Bohlen (Saxony) and Briix (now Most, Czech Republic) producing town gas. The position of the Lurgi dry ash process as the only pressure gasification system for many years, together with continued development, for example, in scale-up, automation, and operational optimization, have all contributed to the commercial success of this technology.

Standardized reactor sizes are shown in Table 5-2.

These figures for throughput and gas production are nominal figures, which are substantially influenced by the quality of coal processed. For instance, Sasol reports

achieving 30% excess throughput compared with the original rated design (Erasmus and van Nierop 2002).

Most commercial gasifiers operate at pressures of 25-30 bar. A demonstration plant has been operated at pressures of 100 bar (see Section 5.1.3).