We stand at the top category of predictive plant maintenance
Overall, the modern cement industries hold good health as compared to other continuous process industries in terms of equipment age, efficiency and infrastructure, says Indranil Dutta, Head (E&A), Burnpur Cement. Excerpts from the interview...
Brief us on the major upgradation projects taken up in your plants.
Installing waste heat recovery (WHR) at the rotary kiln, preheater and calciner section which helps enhancement of in-house power generation, about 30 kWh per MT of produced clinker.
Alteration of existing cyclone with low-pressure drop high-efficiency cyclones which helps low pressure drop, lower preheater fan power consumption, lower pressure drop across pre-heater, increase in clinker productivity, and lower maintenance cost. Installation of variable speed fluid coupling (VSFC) for cooler ID fan helps reduce damper loss; power consumption reduces by replacing the higher rating motor to lower rating.
Installing VVVFD for cooler fans can avert damper loss, lower maintenance cost, and reduces power consumption.
How does one decide between retrofitting and a new system?
It can be decided on the basis of factor analysis of the existing plant.
Qualitative factors: External environment like availability of fresh land, limestone, fuel linkage, etc; market demand and barriers like the brand´s stage in PLC (Product Life Cycle); present process technology, design and engineering like if the plant incorporated with the latest technologies, i.e., VRM, WHR, etc; and financial viability analysis like payback, debt service coverage ratio, internal rate of return and other break-even point analyses.
Quantitative factors: Gestation period like site identification, RM quality study etc; plant depreciation and evaluation. Based on the above factors and by applying simple Kaiser Mayer Sampling Adequacy, we may decide whether retrofitting of an existing plant is viable or it is better to switch to a completely new system on the same premises.
How important are preventive and predictive maintenances?
We stand at the top category of predictive plant maintenance. The predictive maintenances (PdM) are carried out when the machines are running in their normal production modes. Some process plants have a weekly shutdown and this is for their preventive maintenance (PM) activities. Though on an average, these PM and PdM have tentative same type of nature, i.e., mainly machine inspection and other lubrication related jobs. But most important, if PdM carries out in a plant, it reduces the shutdowns, which in turn increases production."
What is the time-period for upgradation for electrical/automation systems in a cement plant?
Every product has a limited life period. The cement industry has extreme harmonics in the line voltage and current as VVVFDs, slip ring and induction type motors are being used. Harmonics, higher ambient temperature, hazardous environment in RM section, continuous production, single phasing, over-loading and unbalance load distribution may cause damage to the E&A systems. Although we are taking proper precautionary measures, the E&A systems need upgradation for the optimisation of energy uses and consumption which is one of the essential priorities of the cement industry. Controlling energy current in the production process could increase production capacity and lower the electricity cost per MT.
Now, to incorporate such development, we need to keep in mind the cost-benefit factor. To enhance the life span of the E&A systems, they must be upgraded with the latest available preventers in the market; upgradation time is normally within two to three years.
Next priority is to be given to the PF compensation section. To optimise the PF and its rebate, we may upgrade the APFC panel with heavy-duty capacitors and other updated instruments, as it has a direct impact on the energy bills. Upgradation time is within 3-5 years, depending on the health of the capacitors.
We may upgrade the automation systems that too step by step and as per budgeting schedule. This may help us for better production and smooth running of the plant; upgradation time can be as per working condition and breakdown percentages. Finally, the ´A´ category vital capital inventories like mill motors, transformers which are losing their efficiency due to winding, filtering and other breakdown issues also need upgradation, after analysing their depreciation value; upgradation time can be as per present working condition and depreciated value.