Purifiers/Separators

Question 1

Difference between purifier & clarifier

Answer 1

A purifier is used to separate oil, water and solids. It has 2 liquid outlets, one for clean oil and one for water. Mainly used for FO.
A clarifier is used to separate oil and solids only. It does not have a gravity disc and therefore only one liquid outlet. It contains a seal ring to seal oil in instead.
Mainly used for LO.

Question 2

How a purifier/separator works

Answer 2

• Oil is preheated before entering to reduce viscosity and increase relative density between oil and water
(Closing water comes in and sits under the sliding bowl and raises it.
The bowl blocks the discharge port as a result and sealing water comes in to seal the bowl
System senses the pressure at the discharge to ensure that the bowl is sealed)
• The bowl rotates at ~8000rpm, using centrifugal force to separate oil, water and solids
• The oil is drawn into the bottom of separation discs and back up the discs while
• The water goes outwards and creates an oil-water interface as water is denser than the oil
• Impurities (solids) impact the bottom of the discs and flocculate together
• Clean oil goes upwards into centripetal pump
• When separator discharges, the 3-way valve closes, conditioning water is applied to soften sludge. Opening water comes in and opens the valve, displacing closing water that is holding the bowl up to uncover discharge ports to discharge the sludge to the sludge tank

Question 3

Purifier is vibrating

Answer 3

Do a de-sludge(flush) of the bowl
(3 way valve closes, conditioning water applied to soften sludge. Opening water comes in and opens the valve, displacing closing water holding the bowl up to uncover discharge ports to sludge tank)

• Could be caused by uneven sludge deposit, worn bearings, misaligned shaft, assembly mistake, worn clutch.
• Could also be the motor - bolts loose, windings (loss of phase causing vibrations), check motor amps

Question 4

Importance of gravity disc

Answer 4

If the gravity disc is too big, the oil will pass into water outlet due to water being less restricted
If the gravity disc is too small, water will pass through the clean oil outlet due to water being too restricted

Need to use a Nomogram to determine the correct gravity disc to use. Need to know specific gravity/density of oil, feed temperature and feed rate capacity of purifier.

Question 5

What should the flow through the FO separator be equivalent to?

Answer 5

The vessel’s FO consumption.

We want minimum flow through the separator to air the separation process by reducing flow vector so that the CF force vector can drag solids and water out easier otherwise they can stay in the clean oil

Question 6

Separator isolations

Answer 6

Inform duty, PPE, PTW & RA

Manual de-sludge
Stop separator
Switch off at panel
Switch off at breaker
LOTO
Prove dead if needed

Close oil inlet
Close outlet
Close closing/sealing water & opening water
Close steam if a heater is fitted
Drain bowl and piping
Vent system
Allow to cool