Steam Flow Measurement

[josemg]

I want to measure steam flow and temperature without shutting down the system. System is 100 psig saturated steam nominal three boilers of 1000 bhp each.

What is the best type of measurement devices for this application?

 

[randi]

Originally Foxboro, but now invensys sells a variety of sensing and monitoring devices for steam flow applications. They have sales and service offices throughout north America and the rest of the world. Check with them under :

http://www.invensys.com

 

[ICman]

Depends on the measurement and accuracy you want. Differential pressure instruments, perhaps with a multi-variable transmitter to sense temperature, would work. This includes orifice plates, Wedge meters, Annubars, etc. Or, a coriollis-type meter for a mass measurement (might be $$$).

There are other methods, with various accuracies and expense. There are also several vendors, including Foxboro (Invensys) already mentioned, Rosemount (Emerson), ABB, Honeywell, etc.

Is this just a temporary measurement? Since you don't want to shutdown, it may be. In that case, you might look into an Annubar that can be inserted through a valve. You could also insert a separate thermometer, I guess. I don't think a clamp-on ultrasonic flowmeter will work in steam, but you might check with Panametrics or Controlatron.

 

[xnuke]

I know you want a measurement, but I thought I'd provide a couple of numbers for you:

Temperature of saturated steam at 100 psig is approximately 327.99 deg F (164.44 deg C) from steam tables.

When running at full capacity, you should have approximately 103500 lbm/hr of steam flow. Size your flowmeter accordingly. (34.5 lbm/bhp-hr x 1000 x 3)

Good luck trying to measure your parameters without shutting down the system. We use vortex flowmeters from Foxboro, but they're installed in the piping downstream of the boilers. You'll have to check on the suitability of clamp-on ultrasonic meters for steam like ICman said. I think I remember seeing a presentation by a Panametrics rep that said steam could be measured with their ultrasonic, but I don't know if the transducers had to be wetted or could be clamp-on.

xnuke

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[josemg]

The Annubar meter seems to be the best answer. I guess doing the hot tap with a valve and then inserting the meter thru that valve. We need to check if there is enough space and the means of using the hot tap machine on the pipe header since it is at a height of about 30 ft inside the boiler room.

Other issue is the calibration of this meter. If we calibrate the meter to say 100psig operating pressure but the boiler can only do 80 psig because of the combustion settings are not working properly, we will have false readings. By density adjustment a differential or velocity type meter will have an error equal to:

For differential devices like orifice plates,
%=(SQRT(S.V.actual/S.V.specified)-1)x100
For velocity devices like vortex,
%=((S.V.actual/S.V.specified)-1)x100

% is percent over or under reading.
S.V. is specific volume of saturated steam at operating pressure.
(See Spirax Sarco Design of Fluid Systems Manual page 60)

This usually means an over reading of the real lbs/hr when really the boiler has not reached its rated capacity.

Is there someone with the same situation?

 

[Sierra]

Use a Insertion Multi Marameter Mass Vortex meter with a Hot-tap system. There are systems available to install these uner "hot" conditions. (see

http://www.sierrainstruments.com

model 241)

 

[adil4adil]

if the plant you dont want to shutdown you can put on
vortex flowmeter at bloiler feed water end and further can directly relate with the steam with its density correction at that pressure of 100psig also pressure increase in steam is proportional to temperature here we can say approx. 162oC. Forbes & marshall(India-mumbai)can very well guide on this matter.

adil

 

[MarkTX]

I had run into an installation a few years ago that had a number of insertion turbine meters installed on their steam system. I thought this was odd because of the moving parts of the turbine and the temperature of the steam. They didn't have any maintenance records so I am not sure how much problems they had. The company that made the insertion turbine also made an insertion vortex meter. I just wanted to mention this as another option. In the plant I am working now the management does not like hot taps. I think they would force me to another option, wait until the unit is down, or not install anything. If you want the insertion meters company name let me know, I can email it to you.
Mark

 

[alexpln]

... try to run simulation on Process Control Calculators from

http://www.lavell.lnk.pl

or if the pressure is high you can use ultrasonic flowmeters... Panametrics came up with those.