Wastewater Treatment System for a Lurgi Coal-Gasification Plant

摘要

In response to a Great Plains directive, the Lummus Company developed a system which maximized the reuse of water within the plant and precluded discharge of process wastewaters to any surface stream. The individual processes selected were all well proven on conventional process plant wastewaters. It was only this combination of these processes to achieve zero discharge that appeared unique. The key to successful performance of the originally proposed system was conventional biological treatment of the stripped gas liquor resulting from the gasification of lignite in Lurgi gasifiers. This report was written to describe the wastewater treatment system developed for the Great Plains coal gasification project under construction in Mercer County, North Dakota. This treatment system is one of the most unique design features of the plant. It was developed at considerable expense to Great Plains through test and analytical work performed over a six-year period. The report contains the basic information used to design the wastewater treatment system and a description of the final design. However, some of the detailed analysis and flow stream compositions completed for the detailed design of the wastewater treatment processes are proprietary to Sasol or Lurgi and cannot be included in this report. We make no claims as to the universal acceptability of this treatment system for other coals, other plant site conditions, or other gasification processes. However, the description of the steps taken to arrive at this design may be helpful in developing optimum designs for other similar facilities with similar operating conditions.