Application of Six Sigma DMAIC methodology in thermal power plants: A case study

In the past few years, successful cases of Six Sigma implementation have been reported in numerous manufacturing industries. This technique has also been implemented in some service industries but the same cannot be said about its implementation in process industries. In this paper, an attempt is being made to apply Six Sigma methodology to a process industry taking a specific case of a thermal power plant. DM (de-mineralised) water in thermal power plants is an expensive input material. A DM water make-up cycle is required to compensate for the losses incurred in the water steam cycle due to evaporation, start-up and shut-down, venting, valve passing and blow downs. It has been found that a 0.1% increase in DM water consumption increases the generation cost by Rs. 80.46 Lakhs per annum, which includes the cost of heat loss, extra water and consumption of chemicals. Hence, the Critical To Quality (CTQ) aim, selected for this Six Sigma application, is to reduce the consumption of DM water in a thermal power plant. In the present case study, the process was studied and the implementation of the Six Sigma project recommendation and improvement action plans reduced the mean make-up of water from 0.90% to 0.54% of MCR (Maximum Continuous Rating), accruing with it a comprehensive energy saving of nearly Rs. 296.09 Lakhs per annum.