Case study – power station steam (boiler) feed pump lube oil

Case Study – Power Station Steam (Boiler) Feed Pump Lube Oil

BioKem recently completed a lubrication purification role at one of Australia’s large coal fired power stations. BioKem had previously assisted the Plant during a shutdown; however this call was urgent due to a significant anomaly occurring in one of their Steam (Boiler) Feed Pump oil tanks.

Lubricant: Caltex Regal R&O 32

The Problem In-house lube oil lab reports revealed an ISO 4406 trend of 20/18/14 (NAS 9) over a 12 month period, peaking at 22/19/15 (NAS 11) when they flagged it. This is definitely out of spec for a Steam Feed Pump lube tank, even using a Group 1 mineral oil.

A large quantity of sludge was removed from the on-board strainers. It was later determined that the on-board filtration and coalescer system was not working correctly and the filter housings also held a lot of sludge.

The site had already had a failure of a $28,000 control valve system that was suspected to be from the contaminated oil and continued operation of the unit in this state, was a concern.

The Challenge The main consideration from the Plant engineering team was to stay online and correct the contamination problem ASAP. A reasonable solution could have been to dump the oil and refresh the lube system with a fresh charge of 7,000 of oil. This would have involved the unit being offline so was not preferred! Also, filling with (new) unpolished oil, which is supplied nominally around 21/18/15 (NAS 10) was not going to help.

Considering the urgent nature of the project, BioKem mobilised on a Sunday, to be onsite 6:00 am Monday morning, completing safety inductions and site requirements. We deployed a low profile 140l/min Vacuum Dehydration Oil Purification System (VDOPS) suited for this constrained environment.

Tasked with correcting the SFPT lube oil ISO 4406, and identifying the contaminants, BioKem established a mobile laboratory to patch test samples whilst onsite.

An additional challenge was the tank ports, at 1� diameter, that were too small to flow the required 140 LPM of our purification rig which has 2� connections.

The BioKem VDOPS rig, with a flow capacity of 140 LPM or 8,400l/hr, vacuum dehydration, 2 Âľm filtration, centrifuge and heating. The compact design and low profile of this rig allow us to stage it right next to the Boiler Feed Pump Tank.

Purification Tasks For the 7,000l tank, circulating at 140 LPM, a complete cycle is every 50 minutes, we estimated up to three days of purification, operating 24hrs, to correct the ISO 4406 from 22/19/15 (NAS 11), to a healthy 16/14/12 (NAS 5). times the intelligent maintenance costs. It doesn’t get much better than

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