Reliable Process Performance
Decrease unscheduled downtime and production losses with ValvTechnologies’ switching valves.
The ValvTechnologies four-way switch valve is designed for use in the delayed coker found in many integrated oil refineries. There are two drums in a delayed coker unit that work consecutively while in operation. When one drum is functioning, the other drum is being de-coked. The switching valve is required to direct hot feed to either drum A or drum B. The valve also has the bypass position to divert flow back to the fractionator for or during emergencies. The bypass has the same port dimension as the main drum feed lines. The control package also has the capabilities of providing multiple intermediate positions to provide the capability to warm the new drum while slowly reducing feed to the live drum. The switch valve is the most critical valve in the unit.
Where is this valve usually found?
This valve is found in delayed coker units where multi-port valves are required in high-temperature coking applications. These systems contain sticky residue, solids and other system contaminants.
Common switch valve failures:
The two most common failure modes for switch valves are locking up/coking up and leak by. ValvTechnologies’ solves this customer challenge with valve purging.
Purging is critical for the valve to deliver operational Reliability over expected mission time or scheduled production run between major turnarounds. ValvTechnologies’ purge design is a continuous sweeping steam method: we introduce steam in the upper and lower valve cavity at a higher pressure than the transfer line process. This assures hot resid is effectively removed from valve cavities, thus coke buildup is prevented. This allows the valve to cycle over long productions runs for drum filling operations without “torqueing out”.
ValvTechnologies also purge the spring seat pocket. This prevent coke buildup in spring area and affecting seat to ball sealing. In the event of loss of steam we have sealed the pocket area with a series of graphite seals to isolate the pocket for hot resid entry. This allows the spring to function properly for Isolation purposes.
Belleville Spring Design:
ValvTechnologies’ switch valve utilizes the same spring design as our isolation valves: we use a Belleville spring for consistant compression of the ball to the seat. According to the Spring Manufacturers Institute, the Bellville type spring is best to maintain linear rates in high thermal conditions. Also, the Bellville has a tin profile with no areas for resid to collect and harden unlike other spring designs so the purge and spring design concept in our valve provides reliability in isolation and operation.
Ball/seat hard coatings:
ValvTechnologies coats ball and seat contact surfaces with HVOF RiTech® 31. This coating has been chosen for excellent thermal, cycling and wear resistance inherit in coke service. RiTech® 31 maintains excellent hardness in high temperature applications and doesn’t crack or lose hardness capabilities in elevated temperatures unlike stellite or platings. This propriatary HVOF process is completed 100% in house at ValvTechnologies.
What makes this valve unique?
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