Parametric Analysis and Optimization of Heat Exchangers in a Thermal Power Plant

Abstract

Heat Exchangers are equipments targeted to the efficient transfer of heat from a hot fluid to a cold fluid, mostly through an intermediate metallic wall and without moving parts. The Heat Exchangers are one of the important and critical equipments for the power generation technology as the overall performance of a power plant system is directly affected by the heat exchanger's performance. For a large capacity power plant, a small change in the output makes a huge difference in considerations such as performance effectiveness, total cost of equipment etc. In the present study, an investigation is carried out for the design and performance analysis of heat exchangers such as surface condenser and feedwater heaters used in power plants by changing various critical parameters and optimization of those parameters for power plant optimization. The HEI (Heat Exchanger Institute) Standard’s method is used for designing the heat exchangers and calculations using excel functions is carried out for the thermal design of heat exchangers. The present study is conducted considering parameters such as TTD (Terminal Temperature Difference), Tube Outer Diameter, Tube Material and Cooling water Velocity for a surface condenser. The present study indicates that in case the value of TTD is increased, while keeping the heat duty and length of tube constant, all other parameters such as the number of tubes, the mass flow rate of cooling fluid and the effective heat transfer area decreases. The thermal design calculations considering SS439 as a tube material (instead of SS304) reveal that there is a saving of about 10% in the overall weight of tube material utilized. For the feedwater heaters, the present study is conducted considering TTD analysis and Desuperheating Zone addition in the LP heater. The present study indicates that in case the value of TTD increase, the total area of heater linearly decreases in the LP heater whereas the total area of heater exponentially decreases in the HP heater. A comparison of LP heater without Desuperheating Zone and with Desuperheating Zone shows that if the superheat is available with steam and a Desuperheating Zone is provided to LP heater then the total area of LP heater decreases at a remarkable level as compared to the total area of LP heater without a Desuperheating Zone.