The best way to expand plant capacity is by retrofitting and this is possible only with a systematic and professional approach by both the technology supplier and as well as the end customer, writes V K Pant & K V Anjani Kumar, based on the success story at Meghalaya Cements.
The Meghalaya Cements unit at Lumshnong in the Jaintia hills district of Meghalaya started its production in 2006. Initially, the original supplier provided all the mechanical and electrical equipment along with the engineering for the plant, and guaranteed a throughput of 1600 TPD (tonne per day). Around mid-2010, MCL (Meghalaya Cements Limited) decided to go for plant upgradation to a level of 2600 TPD and the required technical know-how was provided by the same supplier. The upgradation included addition of a raw grinding circuit, coal grinding circuit, second pre-heater tower and extension of cooler. The entire modification could yield a production level of 2200 TPD. Lot of studies were carried out by various technical expert teams and renowned cement suppliers for optimising the plant and a few modifications were carried out without much substantial gains.
In such a scenario, LNVT carried out the plant audit in March 2013 and concluded that there was sufficient margin in the system that needed to be explored, in order to achieve the target production of 2600 TPD.
After a systematic and scientific analysis of the data, LNVT proposed plant upgradation. The proposed upgradation of the plant represents an increase of nearly 16 per cent of the original operating capacity. The findings of the plant audit and the proposed modifications are explained below. It may please be noted that all the proposed modifications are based on very precise calculations in order to achieve optimum performance from the system.
1) The Meghalaya cement plant is a very complex installation comprising a lot of independent machinery. However, individually the various departments have unutilised capacity. 2) New pre-heater string that was installed in the year 2006 allows more scope for changing day to day operations. 3) All the material distribution boxes will be replaced with LNVT distribution boxes to improve the dispersion as well as mixing. 4) Introduction of a settling chamber, to avoid dust carryover to calciner, which was affecting the combustion in the calciner. 5) Modification of tertiary air duct for eliminating the turbulence and smoothing the gas flow for eliminating the avoidable pressure drop. 6) Calciner modification for adjusting the velocity profiles. 7) Adjusting the size of tertiary air duct and inlet area of calciner with suitable modification for balancing the secondary and tertiary air quantities. 8) Top stages of both the strings (twin cyclones) will be replaced with high efficiency single cyclones. This is to reduce the high return dust quantity, thus saving both heat and power. 9) Lifting of String-1 Stage-2 feed pipe to avoid bypassing of calciner. 10) Modification of Stage 3 inlet area to reduce the pressure drop across the system. The comparison of operating conditions before and after modification tabulated below:
All the above modifications (except top stage replacement and Stage 3 inlet modification) were carried out in two phases. The modifications were completed towards the end of November2013. In a span of three days after light-up, the plant could produce 2600 TPD; it recorded the highest clinker production in the month of December 2013.
Increase in clinker production by almost 20 per cent. Coal consumption reduced by almost 5 per cent. Specific air through tertiary air improved, resulting in proper combustion. System is able to run continuously without any operational problems. Both MCL and LNVT are sure that the pant can produce beyond 2800TPD after carrying out the remaining modification work.
In the present economic scenario, the best way to expand the plant capacity is by retrofitting and this is possible only with a systematic and professional approach by both the technology supplier as well as the end customer, as proved to be successful in the case of MCL upgradation. It is ably proved that with properly executed retrofitting, the benefits could be as high as installing a new circuit.
V K Pant, VP (Projects) of Meghalaya Cements Limited K V Anjani Kumar, GM, (Process & Commissioning) of LNVT, Chennai Email: (firstname.lastname@example.org)