Caltex’s magazine for employees, franchisees & resellers
Issue 45 Oct – Nov 08
Article Highlights
The feed rate has been increased despite a hiatus caused by a power failure and poor weather that restricted unloading of crude oil and feed available for the unit. It again shows how refinery experts working together can make a really big difference.
In this issue:
Kurnell skills adding dollars
Ross Langshaw (left) and Jos Kusters with the Kurnell DHTU - producing more diesel thanks to on-site ingenuity.
They’ll be the first to admit their work isn’t always appealing. It involves handling massive machines and tasks of almost unimaginable complexity. Most non-refining people understand little or nothing about what Caltex’s refinery personnel do.
One recent example of refinery employees’ expertise in action was the work done in August and September on the diesel hydrotreater unit (DHTU) at Kurnell by the refinery’s Technical and Operations teams.
Their task: to identify through a process safety study a way to increase the unit’s diesel output.
The DHTU has been making low-sulfur diesel since it was upgraded as part of the Clean Fuels Project in 2006, with throughput limited to around 200 kilolitres an hour. Refinery planners realised that even a small incremental gain in output would be very significant for Caltex.
The challenge
What was holding it back? The main issue was a design condition on a vessel in the refinery known as the flare knock-out drum. In some emergency shutdown scenarios, the DHTU will release gas to the flare drum which must then also catch any liquid that may accompany the gas.
“A key issue with the drum,” explains Kurnell Technical Services Manager John Taylor, “is that it must have a certain capacity to accommodate that liquid. Simply put, our people had to ensure this capacity wouldn’t be exceeded if we increased the DHTU’s throughput.”
Jos Kusters (Technical) and Ross Langshaw (Operations) and their colleagues were soon focusing their attention on the problem. They began by looking at the unit’s operating levels and instrumentation.
The solution
Jos identified that by improving the reliability of instrumentation on the flare knock-out drum and slightly modifying levels at which it operated, they could change the operational range so there was more volume available to capture any liquid that would be carried over to flare in the event of an emergency. (This potentially dangerous situation resulted in an explosion at a Texaco refinery in 1994.)
Jos and Ross put in new maintenance regimes to ensure instruments were operating correctly. This helped them to increase accuracy and allowed them to operate the pump safely at the lowest possible level.
The end result was an increase in throughput from 200 kilolitres to 210 kilolitres an hour.
“We’ve been able to up the feed rate from September,” says John Taylor. “This was achieved despite a hiatus caused by a power failure and poor weather that restricted unloading of crude oil and feed available for the unit. It again shows how refinery experts working together can make a really big difference.”