Cement Energy and Environment

It was found out that the offset in the centre- line of the incoming duct at the joint with the centre line of the ESP was causing the gas to change its natural direction. Gas distribution test - A test was carri ed out for improving the distlibution inside the ESP of kiln no. 2 to ensure that the entire ESP space came into action. as well as to distribute the load evenl y across the ESP's eros section. As suspected, the gas distri bution was not uniform and it was observed from the markings on the wall that the left hand side of the ESP (as seen in the direction of the gas fl ow) was getting overloaded leavi ng the right hand side under-utilised. The test showed that the gas velocity was max imum ( I m/sec) at the bottom portion and minimum (0.04 m/ sec) at the top left corner of the ESP. Though the gas di stri but ion rec orded a 40-per cent RMS. it was observed that the velocities recorded from left to 1ight showed a vast improvement. It was observed during the test that the minimum gas volume of 60 per cent was not available through the booster fan. In fact, the avai lable volume was below even 50 per cent. When the gas distribution te t was conducted for a second time, the gas volume avai lable was found to be just sufficient. The overall pattern of the ga velocity was the same in the ESP. The increase in the velocity was less at the bottom and more at the top. Percentage RMS calculated thi s time was 32.6 wh ich was it self an improvement over the previous test. It may be mentioned that the improvement in the gas distribution resulted entirely fromthe increased gas volume as no modification had been carried out on the distribution devices. After the second test, it was decided that both the booster and the preheater fans are to be started so as to maximi se the available gas volume. When the gas di tribution screens at the inlet were inspected, the top po1tion of the second screenwas blocked. Thi s blocking was removed to reduce the resistance at the top and some of the blocking plates were used to block the bottom of the screen to increase the resistance. After thi s third test was conducted and readings taken, a substantial improvement in the percentage RMS was recorded. The final ga. distribution value i 12.8 per cent RMS. As can be seen f rom th e forego ing res ults, the percentage RMS value was reduced to 12.6 after all the mod ifications were carried out and increasing the gas volume. It is expected that when the ESP is in operation with the full gas volume, the percentage RMS will improve further. Correclii'C lfl'll\11/'C\ Turning vanes were installed in the inlet duct and the inlet nozzle of the ESP to di stri bute the gas uniformly. Gas distribution tests were conducted to fine-tune the gas di stribution pattern . (;as Sncakagt• Pmhlcm The gas whjch sneaks through from below the hopper baffles ex its untreated. In addi tion, it can cause re– entrainment of the dust which is already collected in the hopper. Fig.3 shows the portion of the oas sncakino 0 0 below the treatment zone (through the hopper). The darker portion on this support is the marking made by high velocity gas. The profile of this cleanswface clearly indicated that the gas was entering the hopper with a high velocity (estimated to be 4 to 5 m/s). Lt was also observed during inspection that the lower one third pottion of the baffle was clean due to the high velocity gas hitting it. Funher, the gap below the baffle was found to provide a low resistance path for the gas to sneak. / Fig 3 Sneakage through hopper inspection of the ESP also revealed that a p01tion of the total gas volume was sneaking through the trough type hopper. Such sneakage of the gas causes higher emission, since untreated dust-l aden gas reaches the stack and also scoops back the collected dust from the hopper into the gas stream.