Cement, Energy and Environment

Productivity Improvement through Process Optimisation - NCB Experiences Rabindra Singh, Naga Kumar, Ramachandra Rao National Council for Cement and Building Materials 1.0 INTRODUCTION Indian cement Industry has resorted to a number of measures like technology up gradation, process optimization, use of captive power plant, use of energy efficient equipment etc . to reach the present level of productivity. However, there sti ll exists a significant Potential for improving productivity in a number of cement plants. Pro - active approach of cement plant can resu lt in timely action giving immense benefits in terms of increased production, improved quality with moderate to significant reduction in energy consumption thus improving the overall productivity of cement plant. NCB carried out kiln optimization study for a Plant in the Eastern part for a 1 million tonne cement capacity. The result of the optimization has been spectacular for the kiln in terms of improvement in quality and productivity. The kiln production is reported to have increased from 2900tpd to 3200 tpd with significant reduction in heat consumption to the tune of 80 kCal/kg clinker besides improvement in clinker quality in terms of free lime. The paper highlights the efforts of NCB towards process optimization leading to improved production, quality and energy efficiency to prepare the plant to achieve PAT targets of energy consumption besides abating the effect of global warming. 2.0 CASE STUDY 2.1 Problem Discussion The 3.8 m 10 x 56 m long kiln (3000 TPD clinker) was having the problem of high free lime in clinker and coating formation in burning zone resulting in reduction of output besides high preheater exit gas temperature and high heat consumption of 880 kCal /kg clinker. 2.2 Observations Kiln condition before and after implementation of NCB recommendations are shown in Table 1 our observations are as under: Table 1: Kiln condition before and after PARAMETER Before After Kiln Feed rate TPH 187-189 205-210 Kiln RPM 3.7 4-4.5 PH fan outlet temp. deg. C ( String-1) 376 365 PH fan outlet temp. deg. C ( String-1) 395 385 Tertiary air temp. deg. C 895-901 950-980 Kiln 1/L- 0 2, I CO% 0.51-0.001 /0.8-1 .06 1-1.5/0.00-0.2 Specific heat consumption 880 Kcal/kg clinker 800 Kcal/kg clinker 2.2.1 Plant Operation Kiln was operating with deficiency of combustion air with oxygen percentage varying from 0.51% to 0.001 % against the normal value of 2% and high CO formation in the range of 0.8% to 1.06% aga inst the normal value below 0.1%, high PH exit gas temperature of 375 OC & 395 OC at string 1 and string -2 respectively against the normal value of 310 OC & 330 OC for five stage preheater, low flame momentum at 1275%m/sec. high kiln feed LSF variation is in the range of 110-119, high degree of calcination is in the range 98-99% at kil n inlet. Operating parameters of the kiln IS shown in figure 1 & 2