Natural gas-driven pneumatic controllers have long been used in the oil & gas industry . A recent report from the partners of the Natural Gas Star program estimates there are over 500,000 pneumatic controllers installed across different segments of the oil & gas industry . It is estimated that 85,000 of these are installed in the transmission sector and are driven by natural gas . The balance ( 400,000 in the production sector , and 13,000 in the processing sector ) is either driven by instrument air or natural gas . Many of these are lowpressure pneumatic actuators that rely on regulated pipeline gas pressure but utilize regulators and relief valves . |
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Different applications will require different solutions depending on several factors . Some of these factors are the size and layout of the site , the number of controllers on the site , the availability of grid or solar power at the site , and of course economic considerations . There is no one solution that is best for all failsafe automation applications . |
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Current emission-free solutions include electric actuators , electric spring-return actuators , self-contained natural-gas-driven actuators , and spring-return gear actuators ( either with or without electric operators ). New systems provide a clean solution for retrofitting many of the above-mentioned existing low-pressure applications . This eliminates the need to replace the actuator and deal with mounting hardware required to match the valve to the actuator sometimes resulting in field installation issues . The use of this new technology allows for installation at the actuator , eliminating the need to run costly tubing across a site . |
Figure 3 : Energy savings using Hybrid Automation . 1
How Does This Technology Work
Upon system start-up , the platform goes through an initial pressure charging of the accumulator . Once charged , external air is no longer used to power the pneumatic actuator . The system is a totally closed loop , which recirculates the internal air with no connection to a remote compressor station . This is a stand-alone platform requiring a source of power that can include solar .
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Figure 3 illustrates the energy efficiencies of the closed-loop operating system versus the industry standard ‘ open loop ’ pneumatic system , which vents exhaust air to the atmosphere . |
Looking Forward
Battery backup and supercapacitor failsafe actuators have their place and will see an increase in demand for lower torque output applications . The total cost of ownership with battery backup and supercapacitor failsafe actuators is a desirable attribute . Like all failsafe actuation , electric actuator performance must fit the application . Frequently asked questions / comments include :
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• Are slower cycle speeds during normal CW and CCW operating conditions a consideration ?
• How tolerant is the electric failsafe in high-vibration applications ? And
• In remote areas , will the current draw to operate the electric actuator be issue ?
By converting a pneumatic actuator to zero-vent to atmosphere electrically controlled platform , the pneumatic actuator line has a new revenue stream . Applications , where venting air during operation was an issue , can now expand their account base .
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• What are the maintenance requirements for the battery backup failsafe ?
• Effects of battery degradation in hightemperature environments ?
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REFERENCE
1 . Environmental Protection Agency . ( n . d .). Convert gas pneumatic controls to instrument air - US EPA . Retrieved April 5 , 2023 , from https :// www . epa . gov / sites / default / files / 2016-06 / documents / ll _ instrument _ air . pdf
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