TECH TALK
One solution for detecting relief events has already been discussed . A WirelessHART ® acoustic and temperature transmitter mounted on the discharge of critical relief devices indicate when a release event is occurring , Figure 4 . Pairing these devices with downstream flow measurement on the flare header allows plant personnel to immediately detect a relief event , calculate the magnitude of the release , and move quickly to resolve the overpressure condition .
Open thief hatches , gauge hatches , and pressure relief manways are another source of vented emissions . Thief hatch and gauge hatches can be inadvertently left partially or fully open , and tank pressure vents can lift undetected . Solutions for these devices can be as simple as a switch which detects when the hatch or vent is open , position sensors which indicate when a tank vent is operating , or monitoring tank blanketing regulators to indicate developing problems , Figure 5 .
Figure 5 : A WirelessHART gateway and a variety of wireless field devices can reduce vented emissions by detecting open hatches , tank blanketing issues , and tank pressure vent releases .
A WirelessHART gateway enables a multitude of devices to be inexpensively installed across the plant . These devices provide a means for plant personnel to immediately detect and react to releases and stop them quickly .
Another significant source of vented emissions occurs at remote oilfield sites where natural gas is used to actuate pneumatic equipment because instrument air is not available . These devices bleed natural gas to the environment constantly , and environmental agencies across the globe have targeted this equipment , mandating low bleed or even zero emissions .
Automation providers have introduced a broad array of very low bleed and zero emission alternatives for these remote sites . The most common solution involves low power , electric valve actuators and electronic transmitters . These devices cut methane vented emissions to zero , while providing information to enable a host of advanced process control strategies , each of which can be implemented from a remote location . This solution yields dramatic emission reductions , while generating significant increased profit from greater well throughput , tighter control , and reduced maintenance and operating costs .
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Real World Savings
Several facilities have employed these technologies to not only achieved dramatic emission reductions , but to also experience significant cost reductions that quickly paid for the project .
One refinery installed flow meters and relief valve acoustic detectors on their extensive flare header system . The project paid for itself in five months by providing plant personnel with the information needed to immediately detect and stop relief events , as well as detect leaking relief valves . This allowed the plant to reduce overpressure events , which had been costing between USD $ 2,500 to USD $ 50,000 per release .
Several oil companies are actively pursuing wholesale electrification of their well site valves and instrumentation . The expected savings are nearly USD $ 1 million per well due to increased production , reduced losses , remote control capability , and significantly improved operation .
The array of technology solutions and equipment options are extensive , so end users may find it helpful to consult with their valve vendor to determine the best choices for achieving their emission reduction goals .
Conclusion
There are many sources of fugitive and vented emissions , included but not limited to valves , thief hatches , flanges , seals , and various types of instruments . Each of these sources can be monitored using a variety of techniques and solutions , such as :
• Live-load packing .
• Bellows seals .
• No-bleed controllers .
• Electric actuators .
Proper selection of devices to limit emissions is the first step , for example correct valve types and sizes . Once the right devices are selected for either new or retrofit applications , the next step is installing monitoring devices as appropriate to detect , and in some case measure , emissions . Vendors offering a comprehensive line of these types of devices , along with corresponding domain knowledge for applying solutions , can assist to ensure proper selection and application .
REFERENCE
All figures courtesy of Emerson .
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Marcelo Dultra is a process industry director for Emerson ’ s Automation Solutions business in Houston , Texas , specializing in pressure relief valves . He has over 25 years of experience in process automation and safety systems . He received his BS degree in electrical engineering from Unicamp in Brazil and his MBA from Texas A & M . Marcelo has worked in multiple projects involving digital integration , fieldbus networks , safety systems , partial stroke testing , and wireless valve monitoring .
Emily Thomas is a marketing director for Emerson ’ s Automation Solutions business in Marshalltown , Iowa , specializing in control valves . She received her BS degree in chemical engineering from Purdue University , and for the past six years she has worked on developing strategies to grow Emerson ’ s position in the process industry through new product innovation , improved customer experiences , and customer lifecycle support .
Dan Myers is the director of business development for Emerson ’ s Actuation Technologies business . He joined Emerson in 1999 as a project manager , and he served in various sales and management roles in his 22-year career .
20 Valve World Americas | September 2022 • www . valve-world-americas . net