CEE Oct-Dec 2002

IN-HOUSE MODIFICATIONS Lakshmi Cement. a division of JK Cor p. Ltd is sit uated in southwest Rajasthan. Total production capacity of the unit is 2.4 mill ion tpa of cement and the plant has two operating dry process ki lns, two vertical rolle r grindi ng mill s, two coa l mill s and three cement mills. It is eq uipped with • state-o f-thc art po llution cont ro l and monitoring facilities and SPM em ission levels are maintained consistently below 40 mg/Nm' . The plant was supp lied by M/s. Fuller. India. The performance of the pollution con trol equipment is excellent, with the exception of the 0-Sepa bag house for cement mill no. 2. where operating diffe rential pressure was recorded at slightly higher during the commissioning of the mill. Cement mill no. 2 was installed in 1996, with a rated capacity of 150 tph. The miII is 14 m long x 4.6 m dia and is equipped with a N-3500 0 -Sepa separator. When the miII was commissioned, the operating differential pressure (DP) of the O– Sepa bag filter was on the higher side i.e. 230 - 260 mm wg. This was due tn the high air-to-cloth ratio i.e. 1.38 rn 3 /m~/min and the high in let dust concen tration i.e. 715g/m\as there is no pre-collector between the separator outlet and bag fi lter inlet. When the mi ll product ion op timi sat ion prog ramme was implemented, the flow requirement throu gh the 0-Sepa Bag filter increased, i.e. the se parator air requ irement per ton of material fed to the 0-Sepa. This resulted in a fut1her increase in O-Sepa bag fi Iter DP from 280-300 mm wg and power consumption by the bag fi lter fan. This increase became a bottleneck in the optimisati on of the mill , the refore preve nting the expected re sults from being achieved. The following options were available in order to reduce different ial· pressure: • Replacement of ord inary polyester fil ter bag with high efticiency PTFE membrane laminated po lyester filter bags. • lnstalla1ion of pre-collector between th e 0-Sepa sepnrator outlet and the bag filter inlet. • Installation of an additional parallel bag hou se to the existing one. • Conversion of bag filter clea ning mechanism from plenum pulse type to jet pulse type. The company studied all of these proposals in detail and found that these options were either ca pital intens ive or were not feasible due to space constraints. Sin ce the options avai lable were either ve ry expensive or were impract;cal, the company began to conce ntrate on low-cost options with high yield. • Increasing the module gas inlet opening The open ing provided at the inlet of the hopper was originally 1631 x 743 mm and was increased to 2435x743mm. This rise in the gas inlet size of hoppers resulted in a drop of gas inlet velocity from 6-4 m/sec and a resultan t drop in overall differential pressure of the bag house was observed as 15 - 20 mmwg. • Increasing cleoningji·equency The clean ing frequency of bags has been increased by adj ust ing the dwell time from I0-3 sec in two phases. The increased cleaning frequency of the fi It er bags has inc reased the compressed air consumption. although a drop or approximately 20 mm wg in DP was recorded . • fnstaflation oflour modzdes in 32 the series of 1he existing bag filter As estimated. the company has spent approximately US$ I0 000 on the execution of all the three jobs and the resu lt s achieved have proved beneficial in several ways. The payback period has on ly been 3 months. • increasing !he length of.filter hog and cage The replacement of the fi Iter bags is being carried out in phases with increased- length filte r bags. In the first phase, old fi Iter bags have been replaced with new ones, the length of filter bags in six modules has been increased and the DP is able to be fu rther reduced by another 20 mm wg. At present, the operating DP is in the range of 150 -- 170 mm wg and the power of bag filter fan has reduced by another 20kW. Minor modificati ons involving less capital investment and down ti me in po ll uti on control equipment can produce substantial results. Any plant having similar kinds or problems s hould concentrate on similar in-house modifications, as this not on ly creates a sense of scif-satisfaction, but also saves the company cons iderable cost. Courtesy: World Cement July 2002. Pp73-75. Fax: +4-1(0)1252 718992 E-nwil: nwil@worldcenJenl. com Weh : www. worldcemenl.com . BURNING THE MIX Linda M Hills el al. Scientists Construction Technology Laboratories, Inc A comprehensive understanding of the chemical and physical aspec ts of raw materi a l transformation into c linker is an important founda tion to inc rease prod uction. red uce costs . and improve quality at the cement plant. Thi s pape r, thi s year's prize -·