We have kiln with off-line calciner and five stages preheater. The reading of cyclones outlet gas temperatures and pressures till 2004 were:
Cy-1: 330 °C & 86 mbar.
Cy-2: 545 °C & 64 mbar
Cy-3: 720 °C & 53 mbar
Cy-4: 800 °C & 44 mbar
Cy-5: 825 °C & 24 mbar
After 2004 the annual stoppage of the plant reduced due to shortage of cement in the country and as a result the maintenance of the preheater stopped. From 2004 to 2007 our kiln condition was upset due to worn out of some dip tubes, false air and hot spots in several areas of preheater, etc. End of 2007 specialist was called to supervise the work in the preheater and he really did good work in short time .... brick lining and casting work in the rizer duct, fixing new type (short) dip tubes in three cyclones, replacing and casting kiln inlet plate, and etc. anyway, after this stoppage kiln started but we couldn’t reach to the maximum feed rate as it was in 2004 and we have observed changing in the preheater cyclones reading especially in cyclone one temperature & pressure:
Cy-1: 348-352 °C & 76-78 mbar (Due to this high temp C.T outlet gas temp. couldn’t be controlled)
Cy-2: 560 °C & 56 mbar
Cy-3: 720 °C & 45 mbar
Cy-4: 790 °C & 35 mbar
Cy-5: 820 °C & 20 mbar
We tried to adjust parameters, flame, and materials but there was no any improving. I will really appreciate your help to solve this problem.