×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Boiler Feed Water Pumps oil cooler issue.

Boiler Feed Water Pumps oil cooler issue.

Boiler Feed Water Pumps oil cooler issue.

(OP)
We have experienced increased water content in lube oil of main feed water pump. This lube oil is supplied by shaft mounted main oil pump from lube oil tank to bearings of main boiler feed water pump and main boiler feed water booster pump. Both pump are coupled in series by motor and reduction gear.In lube oil tank, heater remains off and there is no provision of silica jel damp removers. During first operation, water contents remain with in range. But when it is taken out of service, water contents start to build up. Consequently, I have to remove oil cooler to perform hydrostatic rest. Hydrostatic test is qualified. I am clueless about water ingress. What can be reason ?

Daren!

RE: Boiler Feed Water Pumps oil cooler issue.

I would assume your seal between shaft and pump is letting water by. If this is a mechanical seal they usually need to have rotation to work correctly. If the pump stops it should not be pressurised waiting to start otherwise your seal will leak.

Other option is whether there is condensation coming in from the outside air via the tank breather pipe?

but pump seals sounds like the most obvious to me. Can you post more details of the pump and its seal arrangement?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boiler Feed Water Pumps oil cooler issue.

Oil cooler leak would be my guess, since hydrotest fails with cooler inline ( higher pressure water leaks into zero pressure oil when oil pump is not running).

RE: Boiler Feed Water Pumps oil cooler issue.

Hydro test is qualified means it was tested and did not leak?

RE: Boiler Feed Water Pumps oil cooler issue.

(OP)

1. Leakage from mechanical seal is minimum. There is leakage detection line attached to drain cavity if water leakes from mechanical seal. So, water ingress from mechanical seal is no option and it is quite obvious.

2. Hydrostatic test of cooler always qualifies at room temperature (even of dismounted/removed cooler). There is serrated gasket at sealing surface of cooler. We are using 56KR Klingret gasket. There is no problem with oil when if pump remains operational for the first time. When it is downed and taken into service again, oil shows water contents.

Daren!

RE: Boiler Feed Water Pumps oil cooler issue.

Daren, we can't see what you can so it would be good to post the P &ID of the lube oil system and also the section details of the pump.
Where is this drain cavity? That's why we need to see a drawing.

When you say "taken out of service" or the pump is "down" what do you mean?

Just turned off? Or isolated and drained ? Or ??

Is there a breather on the oil tank?
Does it go through a desiccant?

What is used to cool the oil? water? what does this cooler look like?

Why do you have to remove it each time?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boiler Feed Water Pumps oil cooler issue.

(OP)
Water cools the oil.
Pump down means that pump is taken out of service as per operation requirement to take stand by operation in service
Pump remains in stand-by mode.
There is no breather on tank
There are heaters in tank but they are not taken in service as temperature remains in acceptable range.
Is is barrel type four stage pump. I have no sectional diagram at present. But I try to explain.
From free end to drive end arrangement.
Thrust bearing, journal bearings with lybrith seals on both side, mechanical seal , cooling water jacket, balance drum, 4 stage impeller, mechanical seal, cooling water jacket, journal bearing with lybrith seals on both ends.
Designer has provided 5mm cavity between lybrith seal and mechanical seal on DE and NDE side. If oil leaks from lybrinth seal, it is collected in cavity and if water leaks from mechanical seal, it goes into cavity. Then through cavity, this oil/water drains through drain pipe into trench.

Daren!

RE: Boiler Feed Water Pumps oil cooler issue.

What do you mean by no breather on the lube oil tank? There is no filter or no breather?

Doesn't make sense to have no breather.

But if not humid air getting in then where? We need to see some sort of diagram or photo or details of this oil cooler to try and help.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boiler Feed Water Pumps oil cooler issue.

That raises a question, is the oil being cooled to a point that causes condensation? Is cooling water flow being maintained through the cooler while the unit is in standby? What is the temperature of the sump when the unit is idle?

RE: Boiler Feed Water Pumps oil cooler issue.

Also what are the operating pressures of the water and oil in person and standby mode?

Operating temperature?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Boiler Feed Water Pumps oil cooler issue.

Is this oil cooler a plate frame heat exchanger ? - notorious for inter stream leaks.

RE: Boiler Feed Water Pumps oil cooler issue.

Plate and frame exchangers are not notorious for interstream leaks. The fluids are typically air gapped with external leakage routes.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close