In an industrial or waste to energy plant, upon turbine trip, the high pressure steam from the steam generator is attemperated in a pressure reducing desuperheating (PRD) valve and then condensed in the main condenser. In certain instances, the steam from the PRD valve is condensed in a separate heat exchanger often called the bypass condenser.
Some of the challenges encountered in the design and operation of a bypass condenser are:
- High tubeside flow rates
- High temperature differences between shellside and tubeside fluids
- Large shell diameters and extremely small tube lengths
- Large operational transients
The design and construction of bypass condensers is similar to that of steam surface condensers and feedwater heaters. The circulating water from the cooling tower flowing through the tubeside imparts the condenser characteristics, while the condensation and subcooling of the condensate on the shellside impose the feedwater heater characteristics.
A clear understanding of the principles of design of steam surface condensers and feedwater heaters is mandatory for designing a reliable and robust bypass condenser.
Bypass condensers can be designed for a wide range of operating scenarios such as high pressure, low pressure, condensing only, condensing and subcooling, horizontal, vertical, constant pressure or constant level. Performance at off design conditions can impact the hardware design and therefore must be carefully considered prior to finalizing the mechanical design. Maarky bypass condensers are designed to offer reliable performance at all specified operating scenarios.
For more details on dump condensers please refer to technical paper published by Maarky engineers titled “Design and Control of Bypass Condenser” presented at ASME Conference in Anaheim, California, in 2012.
