Importance of proper Boiler feed water quality in Pool Condenser plants
Importance of proper Boiler feed water (BFW) quality in Pool Condenser Plants.
Topic
In 2016 severe damage occurred in the tube sheet of a Pool Condenser (constructed in X2CrNiMo25-22-2) in a Stamicarbon CO2 stripping plant in China. The damage did not occur at the high pressure process side containing the highly corrosive ammonium carbamate. In general corrosion at process side of Stamicarbon Pool Condensers and Pool Reactors in X2CrNiMo25-22-2 is very limited. For Safurex® Pool Condenser and Pool Reactors corrosion is hardly detectable at process side.
In this case specific case, the damage occurred unexpectedly at the low pressure steam / condensate side, were corrosion problems were not expected.
The root cause of this mishap was poor chemistry of the boiler feed water (BFW), circulating through the U-bundle of the Pool Condenser. This was not expected, since water treatment of steam systems is well known and considered normal practice in the industry.
This resulted is severe erosion-corrosion damage of the carbon steel underneath the weld overlay of the tube sheet. This failure mode is also referred to as Flow Accelerated Corrosion (FAC).
Repair of the tube sheet was challenging and considered temporarily, to bridge the time for replacement with a new Pool Condenser.
Based on the outcome of this root cause analysis, counter measures were taken in order to prevent similar mishaps in other Pool Condensers and Pool Reactors. Furthermore, changes are implemented in the design of new Pool Condensers and Pool Reactors. A guideline to control the quality of the BFW and an in-service inspection program are developed to be able to identify any damages during planned turn arounds.
About Alex Scheerder
Mr. Alex Scheerder holds a Master’s in Science degree in Applied Physics from the Technical University of Eindhoven, the Netherlands.
He started his professional career in 1986 as a Research Associate at the NDT (Non Destructive Testing) Department of DSM Research in the Netherlands, involved in research and development of NDT- inspection techniques for (petro)-chemical installations (static equipment) at DSM.
From 1992 Mr. Scheerder headed the NDT Department of DSM Engineering-Stamicarbon, responsible for non-destructive inspections in all chemical process installations of DSM and Stamicarbon Urea Plants worldwide.
In 2001 he joined Stamicarbon as a Mechanical Lead Engineer within the Services Department and later on within the Urea Technology Department, responsible for the mechanical expertise field of the Stamicarbon Urea process. He worked on the development and successful introduction of the Safurex® duplex stainless steel in Stamicarbon urea plants. In 2007 he became head of the Mechanical Engineering & Inspection Department, delivering services with respect to design and engineering of urea equipment (PDP packages), in-service corrosion inspections and QA/QC during manufacturing of critical HP urea equipment. In 2014 Mr. Scheerder became the Inspections & Materials Engineering Head of Department within Stamicarbon and worked on further developments on the Safurex® material such as Safurex STAR and DEGREE. Since mid of 2019 Mr. Scheerder holds the position of Principal Engineer within Stamicarbon.
