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End User Interview
MPT in PGB Exchanger Tubesheet to expose cracks in tubetubesheet joint. Photo courtesy of YPF.
Reparation of cracks in PGB Exchanger tubesheet during 2023 Non Planned Turnaround. Photo courtesy of YPF.
Refractory installation in PGB exchanger. Photo courtesy of YPF. destructive testing( NDT) on both refinery and petrochemical equipment. His role encompasses overseeing new and existing stationary equipment, including storage tanks, pipelines, and heat transfer systems. With a degree in mechanical engineering and a decade of experience in stationary equipment engineering, commissioning, and maintenance, Nicolás shared insights into the heat transfer challenges his team has faced over the past ten years.
What are the main challenges your plant is experiencing with heat transfer?“ Methanol production is a highly integrated and complex process. Our plant was originally designed with a 20-year operational lifespan, meaning that much of our stationary equipment is reaching the point where refurbishment or replacement is necessary to maintain nominal production levels. The biggest challenges stem from high equipment replacement frequency, short turnaround windows, and constant production demands.”“ These issues significantly impact all stationary equipment, particularly heat exchangers. The methanol process operates under high temperature and pressure conditions. For instance, our exhaust gas duct utilizes high-temperature combustion gases to generate high-pressure steam in a vertical exchanger. This steam powers a turbine that drives a high-pressure compressor, which in turn compresses synthesis gas for the distillation stage. If this vertical exchanger fails, the entire process must be halted.”
How do heat exchangers in a methanol plant differ from those in a typical refinery?“ Methanol plant heat exchangers must withstand much harsher conditions than those found in standard refinery operations. The choice of materials, manufacturing processes, and design considerations are far more demanding. High-temperature-resistant materials, complex welding techniques, and rare filler materials are all required.”“ For example, in the exhaust gas duct, temperatures can reach up to 900 ° C, and the exchangers, arranged in a vertical configuration, must endure tube skin temperatures of up to 650 ° C. This necessitates the use of stainless steel or low-alloy steels.”
“ Another critical example is our water preheater, where water is pressurized at 110 kg / cm ². The tubesheet in this exchanger is 300 mm thick, and the tubes are welded only on the tube side. A small gap between the tubes and the holes in the tubesheet allows water ingress via capillary action. Due to the high temperatures of the reformed gas, this water vaporizes, causing chemical accumulation. The combination of residual and in-service stresses, along with high heat flux, induces stress corrosion cracking, ultimately leading to welding joint failures. This results in water losses to the reformed gas stream, directly impacting production efficiency.”“ Similarly, our process gas boiler is tasked with cooling reformed gas at 850 ° C by transferring heat to water in the shell side to generate high-pressure steam, which powers the synthesis gas compressor. To withstand these conditions, the boiler’ s inlet features a refractory lining composed of bricks and a metal cover sheet with ferrules backed by
Reparation of Boiler water preheater tubesheet. Photo courtesy of YPF.
Nicolás Giménez, Head of Stationary Equipment Inspection at YPF. www. heat-exchanger-world. com
Heat Exchanger World June 2025 17