THE SITUATION FOR VALVES: NOT ONLY ENTER AND EXIT
Valves are this type of common aspect in multivariable production and process control systems that regardless of their frequently critical role in loop performance, the procedure industries appear to become taking them as a given. In 2003, Honeywell Process Solutions released research since the performance in excess of 100,000 control loops. Of individuals loops, case study revealed 49% were performing poorly which 16% percent of individuals had sticky valves.
In a
control valve seminar, it held that year, Emerson Process-Fisher Control's Joe Herink, director of PlantWeb Sales stated: "As many as 80% from the process loops today don't reduce process variability and also the control valve may be the leading offender." In the center from the problem were poorly specified and installed valves.
What I'm driving at here's that loop performance relies a good deal on valve performance. But regardless of valves' critical role, companies appear to not be using the sources (that's time, money, effort) to aid the correct specs and upkeep of
control valves within the plants they build and operate. Add a number of fundamental intricacies that lead for an individual valve's cost, along with its total price of possession (TCO), and it is the effect on overall system/operational costs.
However, the buck doesn't hold on there since the economic dynamics flowing through valves don't turn off using the cost from the technology. Simply, loop performance has everything related to precise valve control, and loop performance has everything related to product quality and plant profitability. Hence, precision valve control equals lucrative operations.
Gary Hawkins, a senior technical specialist at UOP LLC, the well-known supplier of process technology and talking to services towards the refining industry situated in Plusieurs Plaines, Ill., states the procedure units they design frequently include specs for 50–C100 control valves. "Our focus is around the overall control-loop performance and also the
control valves and actuator technologies we specify are impelled through the process dynamics we're trying to control."
Hawkins and that I spoke about how exactly difficulties with dead time, response time, valve stiction along with other valve maladies are frequently the opponents of precise process control and just how getting past individuals issues frequently comes lower towards the cost one must pay to achieve precise valve control.
Are UOP clients willing to cover the required valve, fast actuator, and digital control technologies which get them with the process performance weeds and into the sweet clover that precision valve control delivers? Hawkins states his clients depend on UOP expertise to specify what's going to work, but he concedes there's pressure to cost-justify all components and also the discussion could possibly get pretty rigorous if not every benefit could be damaged lower into individuals hard-numbered metrics the bean- excuse me- cost-conscious financial executives need when assigning scarce capital sources. "Sometimes it requires a little bit of belief," states Hawkins, "but the advantages of advanced valve technology is real. Although it is not easy to evaluate them precisely with an individual basis due to the interactions using the overall system. I attempt to convince any skeptics that technologies that may contain the loop nearer to the preferred setpoints, which can react to upsets inside a stable manner, have a lot of downstream value and over-shadow their incremental costs-especially whenever you also think about the avoidance of unplanned downtime and the advantages of diagnostics."
Fortunately, valve and actuator technologies still advance and its likely engineers won't need to work so difficultly to cost-justify valves that ensure precise flow control. One company has a better idea is Woodward Governor Co. of Rockford, Ill. Lately, the organization introduced an exciting-electric integrated control valve system for gas flow control systems. In the center from the valve is really a stem seal design that produces a cascading number of TCO benefits since the actuator will no longer have to beat the ultimate clamping forces required to seal the packing against fugitive emissions. There's no requirement for high-torque pneumatic or hydraulic actuators (or its incumbent hardware) to beat stem friction loads a little, less-costly motor will the job. It's also delivered as the system, filled with digital controls which allow contemporary asset management/networking scenarios- and that can help ease specs/procurement hassles.
Precision flow control is ensured with well-specified, well-maintained and precisely-controlled valves, but with regard to your process, a cent saved might not always be considered a cent earned.