Cement Energy and Environment

4.0 Steps taken to enhance RABH performance. It was analyzed that increase in RABH gas volume, high inlet temperature, high differential pressure and increase in RABH gas velocity were the prime factor for not achieving at par performance of RABH, consequently having adverse impact on overall productivity of pryo processing system. 4.1 Reduction in RABH inlet gas volume: In-order to reduce the RABH inlet gas volume during direct mode of operation, water spray system was installed in ILC and both SLC string top stage cyclones. This system is having the capacity to drop individual preheater exit gas temperature by 100 Oeg C and resultant reduction in RABH gas volume and inlet temperature which in-turn improved the RABH performance to some extent. The issue with this system is huge water consumption of 30 to 35 KL/hr, regular maintenance and high moisture of 5 to 5.5% in gas. This also is extremely critical in view of the plant location in severe drought prone area. 4.2 Up-gradation in filter bag quality Increased gas volume and differential pressure at RABH after capacity enhancement was handled to some extent by replacing existing bags (Non PTFE) made up of fiber glass with Silicon , Graphite and Teflon finish by Fiber Glass, Acid resistant with PTFE membrane for all the compartments of RABH. The gross air to cloth ratio was increased from 0.432 to 0.522 m 3 /m 2 /min after capacity enhancement, up-gradation of filter bag quality helped in reduction in RABH differential pressure (OP) to some extent. 4.3 Reduction in Mechanical pressure drop in RABH by potential modifications possible: Extensive brain storming has been carried out before implementing recent modification like; Thought process-1: Adding two modules in RABH to handle the increased gas volume. This suggestion was not implemented because of huge investment and involved lot of changes in layout. Thought process-2: Converting existing RABH to Pulse-jet model of bag house. This suggestion was not implemented due to high investment cost & change in bag design and was difficult to complete with in the annual shutdown period. Thought process-3: Increasing filtration area by increasing the bag height and diameter. This suggestion was dropped, looking into the inconvenience to use the existing bags, which again resulting into huge investment. Thought process-4: As there was margin in ACR of existing RABH, decided to reduce RABH gas flow velocity at various points by increasing the area of duct and dampers. RABH differential pressure reduced by 50 mmWG by modifying following structural changes in the equipment: a) RABH gas inlet (entry point) area increased from 19.32 M2 to 29.90 M2. b) RABH outlet duct (exit point) area increased from 19.32 m2 to 29.90 m2. c) Module inlet damper area increased from 21.84 m2 to 43.68 m2. d) Module outlet damper area increased from 27.87 m2 to 55.75 m2 by increasing outlet damper from single to double damper. Earlier there were one 00 damper and one RA damper, after modification there are two 00 dampers and one RA damper for each module. (Total 22 modules). e) RA duct area increased from 1.68 m2 to 3.68 m2. 2 -