How efficient is the chloride pre-scrubber in capturing mercury?
There is uncertainty about the ability of chloride pre-scrubbers to remove mercury. Some waste incinerators are reporting very high mercury removal in the chloride pre-scrubbers. Hans Gutberlet published a paper in VGB Kraftwerkstechnik # 72 in 1992 saying that only 35 percent of the mercury was removed in pre-scrubbers in coal-fired plants operated by VKR but the combination pre-scrubber and limestone scrubber resulted in almost total HgCl capture. HgCl represented 90-95 percent of total mercury. The percentage of oxidized mercury is due to the SCR. Investigations on three dry bottom furnaces and one slag tap furnace revealed that while metallic mercury was 40 to 60 percent of the total upstream of the SCR it was only 2-12 percent of the total downstream. Oxidation did not occur in tail-end SCR systems. This was due to the lack of HCl. Investigation was undertaken as to why the mercury removal was not higher in the pre-scrubbers. The conclusion was that the recycled HCl with the mercu
