Condensate polishing plant debottlenecking within a combined cycle power plant considering the limitation of water resources

Abstract

The most challenging problem with using Heller towers is the lack of proper water cooling in the hot air temperature. This matter creates a problem of increasing the condensate polishing plant’s (CPP) inlet water temperature, which deactivates the power plant cycle. CPP inactivation reduces the cycle water quality and damages the power plant's equipment. In this study, the thermodynamic conditions of a cycle were obtained in different weather conditions by modeling and encoding a combined cycle power plant in Yazd, located in Iran, using Thermoflex and MATLAB software. Then two solution scenarios of the air-cooled cooler and wetted-medium evaporative cooling were considered for debottlenecking of the CPP. The investment cost of the ACC was US $ 82,488, and this scenario could solve the CPP problem totally without using water with a payback period of 0.13 years. Using the water injection method, the annual water consumption was 835027 m3. The reverse osmose desalination and wetted-medium cooling investment costs were also US $ 8757300. This scenario could be used for CPP’s debottlenecking as well as increasing the steam cycle's power generation. This scenario is facing a significant challenge due to the high-water consumption. The Air-cooled cooler was chosen as a better solution by TOPSIS decision-making method. If a small-scale investment is intended to solve the CPP problem, the first scenario is preferable. If large-scale investment with profit from excess electricity generation, solving the CPP problem, and without water-shortage consideration are considered simultaneously, then the second scenario is highly recommended.