Sleeved Plug Valves are ideal for Molten Sulfur service. They offer distinct advantages inherent in its design.
There are three main advantages and they are as follows:
The most important advantage would be that of being so called “Cavity-Free” In this case, what I mean by Cavity-Free is that there are no other possible leak paths or cavities where the flow can accumulate other than the cover/steam areas. In the case of Lubricated Plugs the body is drilled in one or more locations in order to install injector to facilitate the inclusion of lubricants. Why is this essential in a Sulfur Plant application? Cavities enable the flow of molten sulfur, which at that service temperature has a high viscosity, to remain trapped and in turn offer the possibility of solidification and reduction or complete elimination of the sealing capabilities of the valve. Even without a proper solidification, the infiltration of those cavities by the slurry-like flow greatly reduces the capability of the valve to operate.
The second most important feature Sleeved Plug Valve over other designs is that the sleeve protects the flow openings and the plug from erosion as well as its ability to be adjusted. All damage due to particulate vehicle in the flow is absorbed by the polymer sleeve, contrary to other designs. Sleeves are not only adjustable, meaning that as the sleeve wears, the tapered plug can be pushed further in and by its taper achieve again a perfect seal, they are also quickly and easily field serviced in the event of complete wear the sleeve can be changed in the field.. These two features not only translate into time savings and extended service life through adjustment, quick and easy re-sleeving but also in significant monetary savings do to lengthy shut downs to disassemble and machine worn metal components that Lubricated Plug valves require during schedule or unforeseen turnarounds.
Finally, the third most important feature would be the lack of regular maintenance required in continuous operation of our valves, unlike lubricated plug valves for example where a lubricant injection is necessary at each actuation. In the case Sleeved Plug Valves, the only maintenance required is the occasional adjustment of the plug depth in order to ensure a perfect seal.
Additionally it is highly recommended, in my opinion a requirement for Molten Sulfur Applications to specify high performance sleeve materials and jacketed valve. In your particular case, given the process temperature of 210° C., you should seek higher performance (polymer) materials other than PTFE. For two reasons:
1- PTFE will start breaking up above 204° C. in continuous service, unless it is used only intermittently, in which case it could withstand the elevated temperature.
2- Higher performance polymers are slightly more rigid and are not only suitable for continuous applications up to 260° C.; they can also withstand higher pressures associated with the type of flow and temperature of the process.
Please let me know if I can be of additional help and can provide more information on the high performance sleeve materials.
NOTE. The reason why I did not mention any particular brand names of the high performance sleeve materials is do to the fact that all mayor sleeve plug manufacturers offer this in a "Proprietary" brand name. Thereby making different claims as to there attributes. However it should be consider that all this materials outperform PTFE.
