What are the key points to address when selecting a valve for sulphur applications?
When we talk about sulphur valves, in most cases they are used in the sulphur recovery unit. Various processes in refineries and gas plants produce gases that contain hydrogen sulphide (H2S) and the amount of sulphur is legislated to meet HSE and gas piping specifications, which is when sulphur recovery unit kicks in. The sulphur recovery unit involves a furnace that heats the feed, a few reactors where H2S and SO2 are converted into elemental sulphur and a sulphur pit into which the elemental sulphur runs down after condensation.
An application full of challenges
The valves in sulphur recovery are subject to rough process conditions, such as high-temperature operations, erosive & sticky fluids, a tendency towards liquid sulphur solidification or crystallization. One key challenge in the application is jamming, because the build-up of sulphur in the valve cavities leads to a torque increase or seizing, eventually resulting in complete failure of the valve. The wrong choice of valves could result in an inefficient operation and unnecessary product losses. Valves also need to meet all safety requirements and efficient flow control.
Key features to ensure high performance and reliable operation
Metal bearings and bearing protection design play an important role in preventing sulphur build-up and valve jamming. True metal to metal sealing in a triple eccentric valve provides values such as long-lasting bi-directional tightness, minimized friction and high temperature compatibility when dealing with such erosive and sticky fluids. A steam jacket on the sulphur let-down valves may help to avoid sulphur solidification. All of these are very important keys to continuous production and profitability, as well as sustainability and fulfilling safety and environmental requirements in processes such as sulphur recovery.
