The Wilson-Snyder Coker Switch Valve can be best described as a diverter valve. It does not cut off flow from the inlet to one or more outlets so that the flow through the valve is continuous during a switch. Used in the delayed coking process (produces anode, needle and fuel grade coke at elevated temperatures), the switch valve is the valve that diverts coke flow from the heater to one drum or the other or sends it to bypass as required. The Wilson-Snyder switch valve has proven to be a rugged, durable valve for this tough service(continually cycles 700 to 950o F). It is an inverted tapered plug valve with the inlet through the bottom and positioned so flow through the valve is continuous during a switch. The design and materials make the valve stronger and more durable than any other design. The body is forged 9 chromium alloy steel developed for high temperature service and the 410ss plug has proven especially durable over the years. The valve body and plug are precision ground to form a pressure tight metal to metal sealing surface.
The Wilson-Snyder switch valve’s performance is greatly enhanced by automatic operation. Precise control of the position of the plug prevents improper seating (causes the valve to coke up and/or gall the seat faces resulting in a leak). Whenever the valve seating has been automated, the valve has had no operational problems and has not needed repair over several turnarounds. Early automated versions proved that automatic operation extended the valve life and reduced the need for repair but did not offer the control to fully automate the switch. Several years ago, Wilson-Snyder teamed up with M.E.A. Incorporated to develop a modern actuator that could be integrated into an automated process control scheme. M.E.A. is an industry leader in electro-hydraulic actuators in refinery applications.
The basic actuator package consists of two components.
- The first is the actuator itself. This is mounted on the valve and includes a double acting ram to seat or unseat the valve with all the force necessary and under precise control, a bi-directional hydraulic motor to rotate the plug, electronic sensory devices to determine the plug position and a back-up hand wheel for manual operation.
- The second component is the hydraulic manifold that controls the actuator. It can use manual valves to control the seating/unseating and rotation or add a programmable controller to coordinate the switch by push button or process control.
There is enough capacity in the controller to control the Wilson-Snyder valve and all associated valves during a switch. This would allow a fully controlled switch that would increase safety and efficiency. The controller can also communicate with the customer’s process control system. The actuator can be provided the hydraulic power necessary to operate the valve.
The Wilson-Snyder switch valve with the M.E.A. actuator provides a system with a proven, reliable valve now operated automatically with a controller featuring precise operation fully integrated with process control. This system allows a customer to operate longer and with fewer operational problems and eliminates the valve as a turnaround concern.
Typical Actuator logic for operating Wilson-Snyder Switch Valves
Listed below is the typical logic sequence proposed for switching from Drum “X” to Drum “Y” and then after extended interval, from Drum “Y” to Drum “X”. The primary valve outlet ports are labeled “Drum X” and “Drum Y”.
- Valve outlet at “DRUM X”.
- Press pushbutton “DRUM Y”.
- Cylinder drives plug off its seat.
- Hydraulic motor rotates plug to 50% position between X and Y and stops automatically.
- Hydraulic cylinder.
- Valve sets in this position until an Operator determines that it is OK to proceed to DRUM Y. An Operator then presses pushbutton “DRUM Y” again (Note: If it is not OK to proceed to Drum Y, press pushbutton “BYPASS and the cylinder will drive plug off its seat, hydraulic motor rotate valve toward Bypass position via Drum X direction and stops and the cylinder reseats plug).
- Cylinder drives plug off its seat.
- Hydraulic motor finishes plug rotation toward Drum Y position and stops automatically.
- Hydraulic cylinder reseats plug.
- Valve sets in this position while coke drum is being filled.
- Valve is to be returned to Drum X position.
- Press pushbutton “DRUM X”.
- Cylinder drives plug off its seat.
- Hydraulic motor rotates plug to 50% position between Y and X and stop automatically.
- Hydraulic cylinder reseats plug.
- Valve sets in this position until an Operator determines that it is OK to proceed to Drum X. An Operator then press pushbutton “DRUM X” again (Note: If it is not OK to proceed to Drum X, press pushbutton “BYPASS” and the cylinder will drive plug off its seat, hydraulic motor rotate valve toward Bypass position via Drum Y direction stops and the cylinder reseats plug).
- Cylinder drives plug off its seat.
- Hydraulic motor finishes plug rotation toward Drum X position and stops automatically.
- Hydraulic cylinder reseats plug.
- Valve sets in this position while coke drum is being filled.
- This cycle is repeated as required.
Profitability, Reliability, Safety
Now you can automate your Wilson-Snyder Delayed Coking Operation with minimum valve downtime-and no costly piping changes or Steam Purging! Wilson Snyder Coker Switch Valves automated by M.E.A. Inc. Only the M.E.A., Inc. Electro-Hydraulic Actuator lets you retrofit your switch valve quickly, easily, safely and economically.
- Promises minimum valve downtime during installation
- Features no costly piping or valve changes- which can save you as much as $150,000! Fits any drum
- Eliminates costly and dangerous steam purging of valves
- Operates without valve maintenance for as long as 10 years... Minimum valve repairs!
- Provides proven performance: M.E.A., Inc. has automated over 35 Wilson-Snyder switch valves in delayed coking operations throughout the world in the past 5 years.
- Operates three ways- automatic, semi-automatic and manual.
- Eliminates problems that ball valves can't handle- heavy crude with inorganics, and frequent and costly repairs. Our actuator and W-S valves can handle it!
- Gives you automatic positive seating and unseating. No manual operation required. Eliminates personnel hazard. No coking or plug problems.
- Delivers push-button operation- local, remote or both- to simplify operator's job and avoid errors.
- Features a PLC-controlled actuator that can control all other shut-off valves... for Total System Responsibility. Continues operation with or without electrical power because of M.E.A.'s electro-hydraulic advantage
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algorithm enhanced with shutter forecasting control. Intelligent solid-state plating power control module gives better plating accuracy and higher speed compared to the other conventional shutter-only or PID-only control system. Typical plate time per crystal is less than 2 seconds (1) (totally 2 plating cycles), with typical frequency spread of less than ± 5 ppm.
