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Anonymous Poster #1

Flow Meter at Condensate Water of Steam Turbine

07/04/2015 5:13 AM

Hi guys,

I need an advice over a Flowmeter, please advise which flow meter will be best on the following application;

· Medium = Canal Water (Cooling Water)

· Temperature = 55 deg C

· Pressure = 2.5 bar g

· Flow = 43,519 ton/hr

· Line size = DN2400 (96 inches?)

Please advise the best solution

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#1

Re: Flow meter at condensate water of steam turbine

07/04/2015 10:59 AM

There are three technologies that come to mind for large diameter pipe: magnetic flow meter, averaging pitot tube, and clamp-on transit time ultrasonic.

ABB makes a DN2000 mag tube that maxes out at ~110,000 tons/hr. Mag meters generally cover the same flow range regardless of manufacturer, so assuming someone makes DN2400 mag tube, extrapolating on the ABB chart shows that a DN2400 would max out at ~130,000 tons/hr, about 3 times your flow rate.

The ideal mag tube size is a DN1400 with a max flow rate of 52000 tons/hr, which uses 83% of the potential resolution of a DN1400 for your 43,500 ton/hr flow rate.

But large mag tube are very, very expensive.

At a fraction of the cost of a mag meter are the two other technologies.

I'm sure someone makes an averaging pitot tube (with a DP transmitter) but installation requires drilling and welding.

A clamp-on transit time ultrasonic flow meter does not require cutting or welding for transducer installation. . You mount the electronics box where it's convenient. Transit time is quite accurate. Not as accurate as a magmeter, but you need to determine how much premium you'll pay for increased accuracy.

Here's a photo of a clamp-on ultrasonic on a 10ft (~3050mm) cooling water pipe. You can see the transducers installed vertically at about 3m and 5m elevation.

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#4
In reply to #1

Re: Flow meter at condensate water of steam turbine

07/04/2015 10:36 PM

I have wondered if a depth/fish locater could be practically adapted for use as a transit time flow meter.

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#2

Re: Flow meter at condensate water of steam turbine

07/04/2015 12:38 PM

Perhaps I am unclear on the concept, Is this really condensate water?

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#3
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Re: Flow meter at condensate water of steam turbine

07/04/2015 3:26 PM

We want to install flow meters at water intake where water will be taken for condensing of steam of steam turbine.

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#5
In reply to #3

Re: Flow meter at condensate water of steam turbine

07/05/2015 12:06 AM

"We want to install flow meters at water intake"

Medium = Canal Water (Cooling Water)

· Temperature = 55 deg C

· Pressure = 2.5 bar g

· Flow = 43,519 ton/hr"

Surely your intake canal water can't be at 55°C! If it is, I definitely do NOT want to visit... That's got to be the exit temperature!

...and I'd like to see that canal that has 2.5 bar g.

Do you really want to install the flow meter at the input (where the water comes from the canal), or do you mean the input to the condenser, after the pump? Clearly the flow is the same everywhere in the loop (unless your system has major leaks, or some of it is evaporated in the process), so the flow meter can be installed anywhere in the loop.

Finally, one of my pet peeves is unwarranted precision. I'm willing to bet that you don't know the flow to 5 digits of precision, especially since you haven't yet installed the flow meter. 44 kton/hr would be a more reasonable figure.

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#8
In reply to #3

Re: Flow meter at condensate water of steam turbine

09/19/2024 7:51 AM

That's "cooling water".

The term <...condensate...> is usually process steam that has done its job and is being returned to the facility's hot well ready for re-boiling to make steam.

  • Why are these instruments required? After all, the flowrate is already known flom the above.
  • What is the justification for investment in them?
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#6

Re: Flow Meter at Condensate Water of Steam Turbine

07/05/2015 8:04 PM

Oh double plus yes on the accuracy peeve.

It is perhaps the most critical issue in specifying a flowmeter - how accurately do you need to know the flow.

In this case as with others I am a little shocked about the temp but lets say that the canal water comes in at 15C laves at 55C for a 40C rise. At best I would guess at temp measurement to 0.1C so you need 0.25% measurement to match the temperature measurement which would be +/- 100kg/hr.

For this sort of measurement again you are looking at low pressure drop and low space devices (an orifice plate need 10 x diameter upstream needs a straight run of 80ft) so the devices mentioned above are the ones I would be suggesting.

Mag Flow - best accuracy, most expensive, probably needs the most space for the installation

Averaging pitot tube - cheap, probably adequate accuracy, may need the longest straight run of piping, has to be installed in the piping requiring hot tapping welding etc.

Ultrasonic - pretty cheap, more that adequate accuracy, small space and run installed externally.

If the plant is existing I would go for the ultrasonic as I am GUESSING it gives you adequate accuracy but you will need to get an expert in to confirm that your installation location is suitable and will give the performance that you require.

Please do consult with an expert with all the important data and sensible assessments of accuracy. e.g. For control of your plant I think that +/- 100kg/hr is more than enough but if you are being charged for the canal water then maybe the bean counters would like something that does +/- 1kg/hr. These are things that we just don't know.

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#7

Re: Flow Meter at Condensate Water of Steam Turbine

07/15/2015 7:13 AM

Sonar Flow meter-more expensive than the others mentioned, but labour cost is low.We have been using Sonatrac for the last 6 years and it has not missed a beat.

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