The PSA unit in a petrochemical plant handles the purification of hydrogen, an extremely demanding industrial gas process that requires perfect tightness with high cycling, fast response time and short shutdowns. The reliability of the valves in a PSA unit is crucial and requires a detailed focus on maintenance programs and spare parts availability.
The French refinery wanted a partner who could ensure reliable PSA unit operation and top-level safety while optimizing maintenance costs and anticipating failures. Another goal was to improve maintenance through diagnostic tools.
The refinery had previously trusted Metso to check valve conditions whenever needed throughout the years. This positive experience, along with our field-proven results in the sector and years of product and spare parts expertise, led the refinery to ask us to help design a comprehensive maintenance strategy for the plant’s PSA unit.
Customized maintenance program
First, we carried out a complete valve condition audit, checking all devices, identifying obsolete devices and recommending upgrades. Then we proposed and implemented a maintenance program that included diagnostics, repairs and spare parts.
We overhauled and upgraded the 60 existing valves with the Neles® SwitchGuard™ SG9000, high-cycle kits and Neles® ND9000™ valve controllers. An additional 36 valves were delivered for the PSA unit expansion, making all valves interchangeable.
Valve condition is monitored through an advanced device and asset management software which provides an accurate flow of information during all stages of the production process, allowing the refinery to manage maintenance activities with sufficient time to order spare parts and plan for service operations.
A total of 24 valves were delivered to cover one bed while another complete set was in stock in case of failure. Thus, one set is always on site when the other is being maintained.
Attentive customer support
Nowadays, our technician visits the refinery four times a year to analyze data and give recommendations according to the defined plan. Based on the spare parts consumption history and criticality analysis, all obsolete items are removed and just the necessary spares are stocked to make certain the refinery has optimal inventory for the PSA unit. All spare parts are included in the customer management system. Orders are placed automatically, refilling stock as needed.
The maintenance agreement includes regular training during each visit to keep the refinery’s staff updated.
Increased reliability, optimized maintenance
Before the implementation of the upgrades and monitoring solutions, the refinery was losing a few million euros in revenue in 2007 and 2008. Since implementation, no unplanned shutdowns have occurred at the customer’s PSA unit.
The customized maintenance strategy allows the refinery to monitor valve conditions continuously and prioritize day-to-day actions. Spare part needs and maintenance plans are now clearly defined. Maintenance intervals have been extended to 2.5 years and maintenance activities can be conducted without stopping production.
Today, the PSA unit is highly reliable. The refinery also has seen increased safety levels, optimized maintenance costs and reduced unplanned shutdowns.
Our attention to details and reliable customer service have brought success to this refinery’s operations.
This topic has previously been published in Petroleum Technology Quarterly Q1/2016, Technology in Action section.