Design rules for steam condensate systems

摘要

This master’s thesis focuses on the design of steam condensate system of steam power plants. Condensate is generated when fractions of extracted steam from the turbine transfer heat to feedwater in the feedwater heaters. Also small amounts of condensate form in steam pipelines due to radiation heat loss. The condensate produced in the steam using equipment and pipelines should be removed as quickly as possible in order to avoid various problems, such as fractures in pipeline fittings, loss of live steam and so forth. The recovered condensate is treated water containing sensible heat that accounts for approximately 10% to 30% of the total heat contained by the live steam. Thus the boiler fuel demand can be potentially reduced from 10% to 20% by economically recovering hot condensate. The proper design of condensate system requires detail knowledge about condensate piping network, different components of the system as well as various problems associated with condensate flow both in steam and condensate pipelines. In this study, major components of steam condensate system are presented, followed by a discussion of most common problems with condensate, such as water hammer, flash steam, pipe erosion and so on. For optimum design of steam condensate system, the study highlights recommendations for the slope of horizontal steam and condensate pipelines, analysis of condensate flow behaviour in upward inclined steam pipes, sizing of components, such as drain pockets, discharge lines from steam traps, and the importance of using different components in steam condensate system.