(48b) Design and Optimization of High Temperature Heat Exchangers

Abstract

This paper summarizes issues concerning selection, design, construction, operation, and maintenance of High Temperature Heat Exchangers (HTHE).

Historically, HTHEs were mainly used for gas turbine engine recuperation and flue gas recuperation. Recent application areas are found in low emission power plants, hydrogen production, high temperature fuel cell systems, and Carbon Dioxide (CO₂) capture and sequestration (CCS).

While it is evident that weight and volume are not vitally important in stationary power plants, there is a strong incentive to reduce both weight and volume of HJTHE because considerations of shielding, remote handling, fluids inventory, hazards, control response rates, and costs. For marine power generation weight and volume become critically important.

Depending on the HE construction, there is a threshold for the maximum operating temperature. Beyond this temperature level, the HE cannot be used, or special design and material considerations are required. This threshold is usually considered to be 600 °C.

This paper presents information about issues of high-temperature Shell-and-Tube heat exchangers, for services up to 1100^oC. Materials selection, confidence in heat transfer and pressure drop predictions, mechanical issues associated with thermal strain cycling caused by changes from low to high load were discussed. The current gaps in design manufacturing, and operation in this field were identified with the objective to improve high-temperature heat exchanger efficiency, economic feasibility, and safety.