Benefits of Rotork Actuation for Vital Refining Process

Test and development co-operation confirms the benefits of Rotork actuation for vital refining process

Published: 31st March 2011 | Issue 16

Expansion turbine installation equipped with a Rotork IQML actuator

Expansion turbine – also known as ‘turbo expander’ - technology performs a critical function in the upstream processing of natural gas. Expansion turbines are generally used in low temperature processes involving the extraction of hydrocarbon liquids from the natural gas.

Rotork’s extensive experience with the equipment, with energy clients including major names in the oil and gas industries, has precipitated important development work involving the use of Rotork IQML modulating linear electric actuators to improve the efficiency of turbo expander performance. The Rotork actuators are used to operate the inlet guide vanes that direct the flow of air onto the turbo expanders’ rotor blades, instead of pneumatic actuators that have been traditionally specified for this duty.

Rotork has worked closely with both manufacturer and enduser to verify that the performance of the IQML actuator meets the arduous and continuous operating requirements of this specialised duty, which is entirely dictated by the downstream demands of the refining process. Within the actuator, accurate positioning is ensured by fitting the Rotork Folomatic analogue position controller with appropriate deadband settings, whilst the actuator’s torque/thrust values are custom-programmed to suit continuous reversal demands in output direction. Improved lubrication of the output screw has also been identified and implemented to ensure long-term trouble-free operation. In addition, the actuator’s data logger has provided essential operating data for a detailed study enabling the manufacturer to identify the changing nature of the air flow at the various positions of the inlet guide vanes.

These developments have been further assisted by comprehensive testing at Rotork’s research and development facilities at Bath in the UK, where millions of starts and stops in conditions replicating accurate site conditions have been successfully carried out in arduous bench testing programmes. As a result of the test and development work, Rotork has modified existing installations by introducing IQML actuators at a number of major refinery sites including Qatargas and Rasgas. One of these installations is pictured.

Rotork’s activities with metering pump sets continue to grow as manufacturers incorporate Rotork electric valve actuators within standard products and packaged plants.

The metering pump is a positive displacement chemical dosing device with the ability to automatically vary its dosing capacity as process conditions dictate. The pump features a high level of repetitive accuracy and is capable of pumping a wide range of chemicals including corrosives or viscous liquids and slurries in hazardous environments including oil and gas installations, refineries and chemical processing plants. The pumping action is operated by a reciprocating piston which is either in direct contact with the process fluid or shielded from the fluid by a diaphragm.

Rotork multi-turn electric actuators precisely control the stroke of the pump, typically operating from a 4-20mA control signal. The 1000 Series actuator from Rotork Process Controls is well suited to this application, featuring a compact mechanical design, 100% continuous modulating performance with high repeatability and resolution, manual override and a simple set-up programme.

The Rotork IQPro electric actuator is also used for this application. In addition to accurate pump stroking capabilities, the IQPro offers the benefits of non-intrusive set up and commissioning, data logging and valve diagnostics utilising Rotork’s popular IQ-Insight software.

The compact dimensions of Rotork electric actuator designs are a further assistance to the products’ adoption in metering pump applications, where the space available between the piston housings is often restricted.

Rotork Controls, Tel: +44 1225 733200
Website: www.rotork.com

Rotork UK