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Show 6 Limestone Injection With Dry Scrubbing (LIDS) Process The B&W LIDS process - shown in Figure 4 - is a limestone-based furnace injection/dry scrubbing S02 removal process. The process actually comprises the cost-effective integration of three commercially-proven flue gas cleanup technologies: furnace limestone injection, dry scrubbing, and pulse-jet fabric filtration. Sulfur dioxide removal occurs in the boiler furnace and convection pass, in the dry scrubber, and in the fabric filter. Limestone is pulverized and injected as a dry powder into the flue gases in the upper furnace cavity of the boiler. Upon injection, the limestone undergoes calcination to form lime, a portion of which reacts with S02 in the flue gases forming calcium sulfate. The flue gases exiting the boiler then pass through a dry scrubber reactor where they are contacted by a slurry containing calcium hydroxide. In the dry scrubber, the flue gases are cooled and humidified to conditions near the water saturation temperature - commonly referred to as operation at a "low approach to saturation temperature". Under these conditions, a portion of the S02 in the gases reacts with the calcium hydroxide. Water contained in the slurry droplets evaporates as the droplets pass through the reactor vessel, and the products leave the dry scrubber as a dry powder still suspended in the flue gases. Finally, the flue gases enter the pulse-jet fabric filter (bag house) where coal fly ash, spent sorbent, and unreacted sorbent particles are collected. The use of a baghouse is a key feature of the LIDS process because of the additional S02 removal it yields as the flue gases pass through the sorbent-containing filter cake on the filter bags. The majority of the solids from the particulate collection device are recycled to a reagent preparation system to produce calcium hydroxide slurry forthe dry scrubber. The remainder of the solids collected are conveyed to disposal and/or utilized. Limestone Injection Dry Scrubber L- Boiler Air Heater Dry Scrubber Feed Slurry Slurry Preparation Solids Recycle Figure 4 B&W LIDS Process Baghouse Stack Solid By-Product to Disposal or Utilization |