Friday, September 30, 2016

50 Year Old Technology Comes South

In the June issue of Hydrocarbon Processing one finds an article written by three people from Valero Energy Corp titled "Utilize an optimizer to blend gasoline directly to ships". Valero's Pembroke refinery build in the 1960's was due for a DCS upgrade, and organisation decided to simultaneously upgrade their gasoline blending system. A simplified graphics of the system is shown in the figure below.

The idea of blending directly to shipment is however not new. Already in the 1970's Imperial Oil blended product directly to pipeline for shipment east from Edmonton to customers in Ontario. There were no laboratory check prior to the blend entering the pipeline, and in those days graphics displays were still in the research labs.So in a way 50 year old technology is coming to Pembroke.

However, it appears the optimizer at Pembroke do take things one step further. First they can blend to 20 different parameters - although most of the time only 5 are used. The article also indicate that the operators have a single display on which to interface with the blending system and start or stop transfers to ship.

As a former control engineer I would have liked to see a copy of the actual operator DCS display of the blending optimizer. I find that such displays are key to acceptance. Especially when there are up to 20 parameter you need to make it transparent to the operator which ones of these are on spec and which ones still have some give away.

Transparency is important especially if you want the operator to take action during a partial system failure, such as the failure a single pump in the blending system. They key is to maintain operator awareness during such events. It also requires the optimizer to be able to run with any subsets of pumps to cope with such a situation.

Some refineries have gone all the way, and completely eliminated the QC lab and gone to online analyzers. This give significant savings and also more reliable data to the process operators. Are you moving in that direction?

If not, I think you should!