Feasibility assessment of the applicability of tri-generation systems in the apparel industry in Sri Lanka : a case study

Abstract

In this study, the technical and financial performances of the first tri-generation plant installed in Sri Lanka were evaluated. This plant was installed at Tee Jay Lanka PLC; a leading knit fabric manufacturer in the local context. In this tri-generation design, the thermal demand of the process was matched and the technology used was the Rankine cycle with a back-pressure turbine. The overall efficiency, heat to power ratio and the net electrical power were the technical parameters evaluated for the technical feasibility. The net cash flow was evaluated for the financial performance. The evaluation indicates that the TG plant operates below the technical performance of a TG system, which uses the same technology. The failure to operate the steam turbine was identified as the main factor for the underperformance. However, the financial feasibility was observed for the year 2016, indicating a positive cash flow throughout the year. The detailed study reveals that the process steam flow variation caused the back-pressure variation and therefore, the tripping of the turbine. It was proposed to alter the turbine control mode from load command mode to the back-pressure mode. However, the turbine startups failed due to high vibration. After the dismantling of the turbine, it was found that the rotor had corroded and the turbine blades were loose. It was sent for repairs. Afterwards, the turbine is to be started under back pressure mode. If the operation is successful, the technical parameters which measure the performance will reach nominal levels. The political factors affecting the performance were also reviewed in brief. The energy efficiency policies of the government are to be strengthened to encourage investment in energy efficiency projects. The policy of importing coal has to be reviewed again to assure a seamless supply chain especially for the small and medium scale users.