Process Gas Cooler Failure Analysis Case studies in Abu Qir
Eng. Elsayed Mohamed Elsayed Elbanna
Eng. Elsayed Moh. Elbanna, PMP R&D Sector Head at Abu Qir Fertilizers Co.
Eng. Elsayed Elbanna brings two decades of technical expertise to the fertilizer and petrochemical sector, specializing in the engineering design, research & development, long-term operations support and project management.
His recent experience had been in a process lead role and had involved in production related problems, bottleneck & revamp studies, equipment design, appraise equipment manufacturers recommendation and to recommend/ implement modifications aiming at the improvement of the reliability and performance of assets leading to the optimization of maintenance cost , as well as he had involved in new project management started from Conduct feasibility studies through EPC tendering process, evaluation, award till successful performance test and handover.
Abstract
Ammonia Plant (II) Process Gas Cooler (PGC) (Stiffened Type) faced a problem of repeated tube failure and tube-sheet propagation of some cracks. The diagnosis of failure revealed that such a failure mechanism is mainly related to the thermal cycle over 30 years from thermal shocks during startups and shutdowns, as well as the restriction of water circulation at the back of the tube sheet (steam blanketing) which lead to Dry – Wet conditions. This condition result in tube wall thinning and exerts additional stress on the tube sheet approaching material yield stress and plastic deformation.
On the other hand, Ammonia Plant (III) PGC (Membrane Type) faced a problem and was replaced twice, the failure in the first Cooler was concluded as a result of tube vibration problems and the PGC was replaced by a new one, but the replaced cooler failure was diagnosis as a result of higher heat flux which exceeds the critical heat flux value of the tube bundle resulting in a phenomena called Departure from Nucleate Boiling (DNB) while adherent magnetite passive film cracked, separated from tube surface and rebuilt again on the tubes surface and the cycle (wet/dry) repeated which finally reduce the tube thickness & failure occurs.
Finally, this paper presents some recommendations to avoid or minimize failure problems in Process gas Coolers.
