installation of oil vapour extracter fan piping

[alroum]

I work in steam power plant utility, it's 2*100 MW, we got a heavy oil return from oil vapour extraction system, may be 1 drum every 2 days,the config of system as follow, suction from lube oil tank, include damper then one running and one stand by fan and outlet damper then oil seperator and then vent pipe, drain from seperator conect to smaller pipe diameter, this pipe drain oil in another smallest pipe. my QUATION is this configuration true or the drain from seperator should be the same pipe end with seal lobe?
note: the P gauge mounted on tank reading 0.

 

[stgrme]

The oil return from the separator of one to two barrels per day seems excessive. Some problems with installation and/or operation are possible.

First, vacuum in the lube oil tank may be too high. Adjust the damper at the inlet to the fans (extractors) to obtain 2 to 4 inches (50 to 100 mm) water column of vacuum in the bearing pedestals (not in the lube oil tank). Since vacuum will be small, use a manometer (rather than a gauge) for measurements.

Next, each drain from the separator, or from the fan housings, should be drained through its own loop seal. Drains should be returned to the oil tank. Do not connect the drain pipes to the suction pipe upstream of the fans. Drains returned to the suction pipe may cause re-entrainment of the oil in the vent piping.

Drain piping should be 1-inch NPS, as a minimum. Drain piping of 1.5-inch NPS would be better.

Best of luck!