Potential of Exergy Efficiency Improvement of Coal Power Plants in Sri Lanka: a Case Study

In the context of energy utilization it is required to harvest maximum possible potential from the available energy sources. Therefore analysis, monitoring and optimization of available energysources and in particular those related to power plants are major requirement in the sector. Generally the energy performances of power plant are evaluated using criteria based on 1st law of thermodynamics. However, subsequent development in the field of thermodynamic studies in particular the exergy analysis was identified as a useful method to design, evaluation, optimization and improvement of power plant performance. It is based on 2^nd law of thermodynamics.

 

In this study, it is aimed to find out the potential of exergy efficiency improvement opportunities in coal power plants through exergy flow analysis. A methodology was developed to estimate exergy flows in coal power plants and efficiencies of major equipment in power plant employing 2^nd law or exergy analysis. This was done according to general equations which are used in thermodynamics. As a result, set of equations pertaining to the thermodynamics behaviours was established to analyse exergy flows in coal power plants.

 

The methodology was then applied to unit 01 of Lak Vijaya power station (LVPS) in Sri Lanka as a case study. In the process, thermodynamic properties of water-steam cycle of LVPS unit 01 under both design and actual calculation were used to evaluate exergy values of critical states of the cycle as well as the resulting exergy flows and related efficiencies of major equipment.

 

Boiler was identified as the major exergy destruction equipment in power plant and consequently it has less exergy efficiency. Hence boiler sub system was analysed to identify potential of exergy efficiency improvement in coal power plants. The main parameters of boiler were used to identify the exergy flow behaviours of the boiler.

 

An economic analysis was also done for the boiler to identify the benefits. Not only steam generating cost saving in power plant but also reduction of hazardous CO₂ emission calculations were carried out.