TLE Furnace WKM & Decoke Valve Valve Operation

[BBMM]

A client plans to simultaneously (USING DCS system) close one motor driven (MOV) valve (WKM valve to Pyrofrac) and at some point in time open another MOV valve (Decoke valve to Decoke, Such that pressures are balanced during the operation. What is a logical way to design this knowing the valves have different cross sectoinal areas (WKM is much larger). is therea web site that explains a methodology? This is safeguardng plan to protect from a closed outlet situation. ANy help is appreciated.

 

[Longinthetooth]

It sounds as if you are going for a decoke completely controlled from the control room. Most everyone installs physical disconnects (Swing ells or blinds) for decoking pipe-ups. That way, the chance of getting air into the process is zero. I think you are talking cracking furnaces, and air in the quench tower or oil frac is something I would hate to be near. All our cracking furnaces have full strength blinds installed before decokes. Time consuming but very safe.

 

[BBMM]

This is actually a safeguarding mitigation to keep from having operators manually close WKM and open the Decoke valves simultaneously with hand wheels and monitor pressure. The would like to automate the manual task with DCS using MOV's on the valves which are gate valves which I don't think will allow them good control and may have motor trips if they have to keep bumping both valves while monitoring pressure.