HOERBIGER valve actuators demonstrate their strengths.
[ Published in HOERBIGER@MOTION November 2014 ]
Open Grid Europe GmbH operates Germany's largest gas pipeline network with a total length of over 12,000 kilometers (almost 7500 miles). Compressor stations ensure that this gas reaches the consumer reliably and in the best quality. Electrohydraulic valve actuators made by HOERBIGER have successfully completed a one-year trial operation at the Cologne-Porz station.
Open Grid Europe supplies more than 450 national and international long-distance gas companies, municipal utilities, industrial customers and gas traders. The annual outfeed volume is approximately 725 billion kilowatt hours, accounting for some two thirds of Germany's entire natural gas consumption. Open Grid Europe's pipeline system is also a central element of the European natural gas network.
On its way to key customers, the gas reaches a peak pressure of up to 100 bar in the pipelines, which decreases steadily during transport as a result of friction and gas withdrawals. Compressor stations are positioned at intervals of 150 to 200 kilometers (100 to 125 miles), where the pressure is raised again for continued transport and the gas is filtered, measured, dried, compressed and cooled in multiple stages. The oldest of the 27 compressor stations in total has been located in Cologne-Porz since 1954, where eight compressors with a capacity totaling 100 megawatts process as much as 2 million cubic meters of natural gas per hour. The station offers 27 flow direction configurations in the pipeline network, allowing for very flexible operation, including a reversal of the transport direction with compression from North-to-South to South-to-North.
ELECTRIC ACTUATOR WITH SAFETY FUNCTION
This business segment is highly sensitive when it comes to safety: "We invest in the safety of our transportation network, and we are as extremely conscientious about protecting the environment as we are about our employees and equipment," is the motto of Open Grid Europe. In the quest for innovations, they came across the TriVAX electrohydraulic actuator, which HOERBIGER developed specifically for the process industry starting in 2009. The actuator blends the strengths of hydraulics – high power density and rigidity, yet simple integration of safety functions – with the ease of installation of electric actuators. There is only one mechanical interface to the valve and an electrical interface to the process control system.
"The unique feature is that the hydraulic system is not even noticeable because it is entirely encapsulated," says Marcus Grödl, Head of the Valve Automation Business Segment at HOERBIGER in Altenstadt. "The closed hydraulic circuit makes our system so reliable that five-year maintenance intervals and up to three million cycles are realistic." For commissioning or in the event of a power failure, it takes just a few steps to manually open and close the valve from the outside using the integrated hand pump. At the same time, the extremely compact and durable actuator requires only 800 watts of power. The entirely piping-free, encased power unit is ATEX-certified, making it also suitable for use in areas prone to explosions as well as outdoors in all weather conditions. This prompted the experts in the Porz compressor station to comprehensively and extensively test this new technology. Previously, electric, gas- or compressed air-controlled solutions were used.
As a result, the site tested the TriVAX Flex model, where the components can be individually configured and designed, while the standard TriVAX unit features an integrated controller unit for traditional standard applications. The test installation was launched during the summer months, when demand is less for gas suppliers, in order to then comprehensively test all the functionalities during the peak period in the winter.
After the one-year test operation was completed, the electrohydraulic valve actuator proved to pose no problems in terms of connecting and delivered flawless performance. Open Grid Europe is now deliberating to switch actuators that need replacement to the HOERBIGER system in the future.