CCI QuickTrak™ to the Rescue

CCI have been providing superior performance and reliable solutions for over 60 years in the severe service valve industry, and the recent retrofit of a Valtek Tigertooth compressor recycle valve in a major gas plant in Western Australia again proved CCI truly deserves its hard-earned reputation as the Valve Doctor®.

A problem was identified at the plant due to a poorly functioning pneumatic actuation system supplied by Valtek. By relying on a system of multiple volume boosters and quick exhausts valves to achieve the performance requirements for speed, the actuation system inherently provided poor resolution and control. Overall the actuation system was not able to provide sufficient protection for the plant’s air compressor.

Compressor recycle/anti-surge is typically considered a severe service application. To prevent compressor surge a quick response time of less than 2 seconds is required, with the facility for extra flow capacity. For the recycle operation, noise attenuation is required and stable throttling, a small signal response and minimal overshoot. Hysteresis and linearity at less then 1% is necessary.  When the valve is in the fully closed (normal operating) position, a class V shut–off or greater is recommended. Common problems associated with compressor recycle valves in the field are inadequate response times, instability, poor control, leakage across the valve, wearing of the valve trim and often sticking of the valve.

The proposal from CCI was to provide a QuickTrak™ system that would guarantee the performance criteria, provide long term digital calibration and control to improve the reliability of the system. The positioning capability of the QuickTrak™ system is very accurate and repeatable. Even more importantly, it does not use a mechanical linkage system that is present on all standard pneumatic actuators to translate linear position.

The major feature of the QuickTrak™ system is the combination of the large capacity spool with a high speed micro processor. As the control signal (4-20mA) is transmitted from the users control system, the controller moves the spool extremely fast to move the air as required between the top and bottom of the actuator. This allows the valve to react quickly to maintain the control variable more precisely.

In addition, there is absolutely no overshoot on the valve motion, thus the long term control is very stable. The usage of a high capacity spool eliminates the need for volume boosters and quick exhaust valves. Also, the use of the internally mounted probe eliminates linkages which cause hysteresis in the position feedback system.

CCI’s actuator and QuickTrak™ control system provides the required two-second stroking time, dramatically outperforming the eight-second stroking time that the Valtek hardware struggled to achieve. By shortening the stroking time and guaranteeing top quality products and service, CCI confidently provides the plant with peace of mind.

Overview of the QuickTrak™ Valve Controller

Mounted QuickTrak™

Published in Solutions Oil & Gas Summer 2006