Small decisions, big significance
As industrial gas processes are highly dependent on valve operations, valves play a critical role in the availability of most industrial gas process plants.
The best performance from industrial gas plants is not delivered by only using best-in-class and reliable valves, but by tying reliable valve solutions directly into the effective maintenance planning of the whole plant.
Reliability and efficiency rarely come from a single source, but are created by multiple smaller aggregates. Smaller decisions, beginning from the design phase to the operational decisions, define how well the plant will perform.
An eight bed PSA gas purification plant in a single production train configuration.
Industrial gas production essentials
The most critical challenge regarding industrial gas production is ensuring reliability and the subsequent availability of industrial gases in processes needing the supply, as for example in refineries and the chemical industry. In practice, this means maximizing uptime and a continuous, uninterrupted supply of gases. At the same time, profitability is an important parameter.
For plants serving refineries without intermission all year round, availability and reliability are absolutely essential to ensure uninterrupted production. Planned shutdowns are generally kept short. This places high demands not only on the process itself, but also on the plants’ components. Furthermore, plants typically hold high standards regarding the environmental efficiency of their production processes.
Gas production options
Industrial gas processes can be divided into three categories: membrane technologies, swing adsorption technologies, and air separation (ASU) technologies. These technologies have a lot in common from a product specification point of view, but they differ a lot in terms of production scale. Whereas air separation technologies are used in large-scale production, swing adsorption and, in particular, membrane technologies provide less output.
Different production environments
Membrane technology is based on the use of partially permeable membranes, which selectively allow gases to pass through the membrane while others are left in the basic gas stream. In terms of demands on valves, this method of separation is the least challenging.
A 20 in. Mapag BK series valve after cryogenic tests according to BS6364 standard.
Swing adsorption option of gas production includes three different main adsorption processes based on either pressure (PSA/VSA) or temperature alternation (TSA). High-pressure differentials are typically present on both sides of valves during the different process stages. Moreover, valves need to be absolutely tight. In very extreme cases, valves might see 1 million cycles per year, which is obviously challenging for any valve design.
The basic ASU process separates air into its primary components, end products being nitrogen, oxygen and several rare noble gases like argon, helium, krypton or xenon. The most common technology in this separation process is cryogenic distillation, which requires multiple stages of compression, purification, cooling and distillation. The major challenges of this multistage process are severe operational and environmental requirements, such as very cold temperatures and oxygen enriched atmosphere. Naturally, these extreme conditions require a lot from process valves, and extra attention to the valve design is needed to secure reliability. Mainly, these valves have to provide long lasting safe and tight shutoff to avoid health hazards and safeguard uninterrupted production to reach maximum availability of the industrial gas plant. In addition, they must provide stable control over fugitive emissions.
Solutions based on experience
For the swing absorption process, valves with enhanced performance have been introduced to maximize the level of efficiency through unparalleled innovations within both valve internals and basic assembly. Specifically, controllability and maintainability have been improved, without compromising the renowned, best-in-class capacity of the valve.
Intelligent valve controllers, such as Neles SwitchGuard (shown here on top of a Neles L6 butterfly valve), are often used in switching processes to secure the reliable valve operations and to maximise the valve availability in PSA processes.
Intelligent valve controllers are often used in switching processes in combination with the valves. The embedded intelligence makes it possible to see online what is going on with the valves and also to store the diagnostic data for later analysis. With the help of an asset management solution, this information can be used to plan the maintenance to ensure the maximal availability of switching valves in the PSA process.
For the ASU process, specific valves have been designed to cover all air separation stages from the compression to the tank loading and distribution. These valves are tested according to international or customer specific standards in lifelike conditions to ensure true valve performance.
Due to the many stages of the ASU process, the optimal plant operation also includes an effective automation system to help operators optimize and control the total cycle. Additionally, it provides relevant maintenance data through integrated condition monitoring.
An innovative approach
As industrial gas processes are highly dependent on valve operations, valves play a critical role in the availability of most industrial gas process plants. These plants all require reliable valve performance to secure the constant supply of industrial gases to the wide variety of processes involving them. By adopting the innovative valve and accompanying solutions that have been developed based on years of experience in the industrial gas field, producers can guarantee the consistent production and boost their profitability.
Mr. Mikko Vuolanto worked as Product Manager Neles and Mapag butterfly valves for Metso Automation. Mikko holds a degree in materials engineering and has been working in various positions within engineering already more than ten years.
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