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Show 13 removal: 1) fabric filtration has been shown to be extremely effective in removing particulate and therefore many trace metals, and 2) the LIDS dry scrubber and baghouse are operating at low temperatures creating a higher potential for trace metals to condense out of the flue gas. Acid gases - primarily HCI and HF - have come under scrutiny primarily because of the large quantity of these substances emitted from electric power utilities. If acid gas regulations are required, coal-fired plants equipped with wet or dry FGD can achieve over 90% removal of HCI, as confirmed in field samplingJ5J Anotherform of HCI and HF control may be furnace sorbent injection. LIDS has both furnace limestone injection and a dry scrubber to effectively control acid gases. Preliminary risk assessment case studies appear to indicate that, compared with trace metals, organic compounds in utility power plant emissions pose only a very small risk to human health or to the environment due to their typical presence at or below the detection limit of current EPArecommended measurement methods. However, if organics such as furans and dioxins are regulated, LIDS has the potential for their control because of the use of a calcium-based sorbent injection process in the furnace/convection pass. The amount of HCI present in flue gas at lower temperatures - around 570°F - has been shown to directly affect the amount of dioxins and furans formedJ6] Therefore, injecting a compound that will react with HCI - such as limestone in the B&W LIDS process - may reduce the quantity of dioxins and furans formed. Overall, the B&W LIDS process should be able to respond effectively to any of the potential air toxics regulations that have been indicated to date. SULFUR TRIOXIDE (S03) REMOVAL Along with improving the emissions capture of today's conventional power plant, B&W is working on improving thermal efficiency of the power plant. One way this is being accomplished in the B& VV LEBS is through the removal of S03. There is evidence that sorbent injection of a calcium-based sorbent into the furnace/convection pass of the furnace removes a large portion of the S03 from the flue gases. Due to the removal of the S03, there exists a potential to reduce the air heater flue gas exittemperature below current standards due to the elimination of acid condensation concerns. According to lEA Coal Research, uSorbent injection reduced the S03 concentration almost down to zero. This is expected to reduce problems of cold end corrosion and make it possible to extract more heat from the flue gases and thereby improve the overall efficiency of the power plant."[7] The B& W LIDS process is therefore able to take advantage of the furnace limestone injection process in improving the overall efficiency of B&W's LESS. This is accomplished by reducing the air heater exit temperature because of the elimination of sulfuric acid condensation concerns - therefore, reducing the overall power plant thermal efficiency. |