Flue gas treatment to remove fly ash and sulphur oxide(s) - with pre:wash to remove fluorine and chlorine cpds. and residual fly ash allowing pure gypsum recovery

摘要

Removal of harmful materials, e.g. fly ash, S oxides, F and Cl cpds., from flue gas involves sepg. most of the fly ash mechanically and electrostatically and the S oxides by exchange with an aq. wash liquor contg. Ca ions in the form of Ca sulphate. This wash stage is preceded by another wash stage for the sepn. of the F and Cl cpds. and the rest of the fly ash in the gas. The process is useful for preventing environmental pollution by flue gas from power stations burning refuse, coal etc. High grade gypsum can be produced and capital and operating costs for fly ash sepn. are reduced.