Jeff Cox, Additive Direct Services
Early in my career as refinery account manager for a process chemical company, I prepared a quarterly performance review report for a major refinery group. After submitting a rough draft to my supervisor, it was quickly returned with red marks stating, "Safety always comes first." I was so excited to proclaim our program's cost-efficiency successes and production benefits that I buried the lede: our continued stellar safety record. How could I do that after what I have seen, especially after running the H2S control program?
I first witnessed the detrimental consequences of H2S exposure during the summer after my sophomore year of high school (back in the early 80s). An older friend of mine from down the street had just gotten a job working on river barges straight out of high school. One June morning, he opened a hatch door on a crude oil barge and his life changed forever. No one knows how long he lay unconscious after being knocked down to the deck from H2S exposure.
After he'd spent a couple weeks in the hospital, I visited and was stunned to find him sitting at the edge of his bed staring out the window in a zombie-like state. The brain damage that occurred from oxygen deprivation left him unable to string together coherent sentences. He could walk a bit and observe some things going on around him, but he was not capable of much else. He was lucky to be alive, but really, how lucky was he? This memory of my friend has been tremendously influential in shaping my views on how to create a safe environment for H2S control and removal.
Reliable sampling and accurate testing protocols are the first line of defense in understanding the scope and magnitude of a potentially hazardous situation. The most common test method used for safety identification is ASTM D5705(M), or the "vapor test." This test measures potential H2S volatilization in a crude oil sample and mimics the potential field exposure of workers in their environment. Extreme care in sampling and handling are needed due to the nature of capturing and containing a volatile gas from a liquid. Samples are easy to degrade and will produce a "false low" result that may lead to incorrect treatment diagnosis with hazardous exposure.
Another test, known as the "liquid test" (UOP 163), is used primarily to determine substance quality and measures the partsper- million weight of H2S in a stable sample. It does not reflect the potential for volatilization like the vapor test, and therefore cannot be used to establish treatment strategy.
Proper chemical selection and application are critical components for a successful H2S treatment program. There must be direct contact between the H2S molecule and the chemical. Installing point-source injection systems upstream of product transfer pumps during oil movement is the most effective operation available to achieve reliably correct testing results.
Terminals have also begun providing in-house treatment programs. Treatment procedures typically fall in line with daily operations. Chemical injection equipment with automated controls is being used in remote locations to make it easier to operate during long hours of transfer operations. This eliminates the need for additional outside personnel on-site and reduces associated safety risks.
Approved chemical and logistical supplies are essential assets for suppliers and operators taking control of H2S removal. Many H2S scavengers have recently been removed from approved usage lists. As those lists continue to evolve, new replacement chemical deliveries should be accompanied by a certificate of analysis to ensure the product has been checked for quality by the manufacturer.
In the long term, stored crude oil will continue to present challenges as H2S is generated in containment by the same microbial mechanisms that helped manufacture H2S during crude oil's creation. Eventually, this oil will be moved for processing and may require additional treatment for H2S removal. Those who control the fate of crude oil also control the safety and treatment procedures surrounding H2S.
Remember: Safety always comes first.
Jeff Cox, Vice President of Technical Sales, Additive Direct Services
For more information, visit www.additivedirectservices.com or call (713) 328-4667.
