New Zealand Refining Co. Ltd. (NZRC) said results from the first in a series of efficiency upgrades to the hydrocracking unit at its 107,000-b/d Marsden Point refinery indicate that the plant is on track to improve diesel processing and lift refining margins.
The refitting of the hydrocracker’s mild vacuum column in March already has resulted in a 3.5% step-up in separation efficiency for gas oil than the company originally had expected, the company said.
The improved separation efficiency stems from the refitting of the column with structured packing, a honeycomb-shaped series of corrugated metal plates that make separation of gas oil in the first stage of processing more efficient and improves the yield of higher-value products from the hydrocracking process, the company said.
“It’s clear that we’re getting far better gas oil separation from the column refit, and with a cleaner cut, we’re able to pull more gas oil out of the column without it being recycled to a second stage of processing, where conversion to less valuable, lighter products occurs,” said Sjoerd Post, NZRC’s chief executive officer.
Post said he expects the column refit to also improve energy use by helping the refinery to achieve gas oil separation at lower temperatures and reduce the amount of hydrogen required in the process.
In addition to the column refit, on which optimization work remains under way, NZRC also has undertaken other upgrades to improve the refinery’s hydrocracking efficiency during the March maintenance shutdown. These include the replacement of catalyst as well as the increased use of natural gas in lieu of produced fuel gases that can be made into marketable products.
A further improvement includes the installation of a pipeline to route bleed from the hydrocracker’s mild vacuum column to the refinery’s butane deasphalting unit, which is scheduled to be completed in the next two weeks, the company said.
“While this is just one component stream in our processing, it is an important first contribution to the series of initiatives aimed at lifting the performance on the hydrocracker which, taken together, are expected to add 66¢/bbl to NZRC’s gross refining margin,” Post said.
Though initially targeted for completion in early April, the March planned maintenance shutdown of the refinery’s hydrocracker was delayed to mid-April amid delays from inclement weather and the need for additional repair work (OGJ Online, Apr. 15, 2014; Mar. 4, 2014).