By Gregory Hale
Out of disasters sometimes comes some good and that is what is happening after the Buncefield, England, catastrophe in 2005.
“One of the results of that disaster was the need for wireless secondary alarming,” said Greg LaFramboise, wireless technology lead for Chevron during his talk Tuesday at the 2012 Americas Triconex Technical Conference in Galveston, TX.
Buncefield was a major disaster caused by a series of explosions December 11, 2005 at the Hertfordshire Oil Storage Terminal, in Hertfordshire, England. The terminal was the fifth largest oil-products storage depot in the United Kingdom, with a capacity of about 60 million imperial gallons of fuel.
The first and largest explosion occurred at 6:01 a.m., which led to further explosions that eventually overwhelmed 20 large storage tanks. The cause of the explosion seems to have been a fuel-air explosion. Essentially, a storage tank overflowed and the vapors ended up ignited and that started the chain reaction of explosions.
At the Chevron Richmond, CA, refinery, the company has a huge challenge with the terrain that surrounds the plant. They have mountains on one side where they have over 200 tanks placed and they have a bay on the other side.
With that kind of topology, they knew they would have to use wireless to ensure a safer environment for the refinery and the surrounding area.
The company already had a wireless sensor infrastructure in place which was already seeing use in process and monitoring.
While they already had a wired monitoring system in place, they wanted this secondary alarming system as an extra safety measure.
“We are looking at alarms that go all the way to the operator,” LaFramboise said. “The alarm will go to the operator for action. There will be no automatic executive action.”
Chevron went to the tanks and placed battery-powered wireless instruments on the top of the tank. These instruments have a battery life of 4 to 5 years, he said.
One of the positive results so far, LaFramboise said, was the “entry point into the system is completely independent from the primary wired devices.”
One of the problems, he said, was there are not enough tank level instrument available that are truly wireless, which means getting its power from a battery
They now have a system up and running and they are currently undergoing an evaluation. One of the problems they faced when they first installed the system was spotty coverage.
“Early on we had flat spots and it turned out we had OPC problems, but after six patches, it is working well,” LaFramboise said.
In the end, wireless monitoring for tank levels may not be for everyone, but it appears to be working at the Chevron Richmond refinery.