Study on reliability improvements of Lakvijaya power station related to the balance of plant systems : a case study

Abstract

Lakvijaya power station is the first coal fired power station in Sri Lanka having an installed capacity of 300MW. During 2012, it has supplied 18% of the Sri Lankan energy demand. The availability factor of this power station in 2012 was 68.8%. This is rather high compared with the average availability factor of coal powered power stations in countries in the region falls between 65% - 90%.According to the contract document, the availability factor of this plant has been expected as 85% [1]. However, there is a strong public opinion created by media that the plant is unreliable and prone to frequent failures. Therefore, any improvement in the availability of the power station will result in improving the public image as well as reducing overall costs spent on more expensive fuels. This research aims at critically analyzing the Auxiliary Systems of the power plant to identify their contribution to the reduction of plant availability and propose means of improving overall availability through increasing the reliability of auxiliary systems. Data related to outages were collected from plant operational logs and defect reportsfrom 22.12.2010 to 09.06.2012. Existing systems and layouts were studied referring to plant operation and maintenance manuals and by field observations. Analyzing thedata, it was found that failures and unsatisfactory performance in the auxiliary systems havecontributed to the low availability of the power plant by delaying re-starts after failures and reducing the plant capacity while in operation. Failures and problems in auxiliary systems such as The Sea Water Pre-Treatment System, De-salination System, De-mineralization System, Chlorination System and the Hydrogen Production and Storage System were critically analyzed during this research and improvements to the designs are proposed based on the results. The present availability factor of 21% of the De-salination System can be improved to 91% by carrying out the proposals made by this research. The availability factor of other systems too can be improved above 90% using the results. Estimated total cost of the proposals is Rs. 543 Million. However, by implementing themRs.2.7 Billion is expected to be saved annually, by reducing the operating and maintenance costs of auxiliary systems and improving the availability of the power plant.Expected payback period is only 2 ½ months. Therefore, the proposed modifications are extremely desirable and cost effective. They will make a good financial contribution due to the expected savings while improving the reliability and the public image of the power plant.