Steam Flow Metering 1

[NeilatNEL]

I am performing a government sponsored review of steam flow metering technology and how it is applied in the UK. I'd be grateful if anyone out there would be willing to share their experiences. Specifically, I am trying to get a handle on the metering methods used and information available to the users. This could cover any industry (probably Process, Power, Geothermal & Food sectors are the main ones). I'm interested in the answers to the following questions (with either reference to a specific application or more general information) :

1. What application did you use the flow meter for?
2. What were your uncertainty, sensitivity, reliability or other specific requirements?
3. What were the operating conditions (pressure, temperature, flow rate etc)
4. What type of meter did you use, and why?
5. Did you have any good or bad experiences? How good was the support from the supplier?
6. How did you measure the steam density?
7. Were there any specific installaton requirements (e.g. steam traps, lagging, straight upstream lengths)
8. Any other comments

I'd also be interested in any sources of information on the subject (e.g. web pages, books, courses (in the UK only!).

The end result of this work will include a web page with freely available reports. This will come on-line in about 18 months.

Thanks for your help.

Neil

 

[quark]

1. For utility billing to four formulation plants.
2. Inaccuracy of NMT 1% of mass flow rate and fit and forget type was the requirement.
3. Pressure is 10 Bar maximum, flow rate ranging from 1000 to 4000 Kgs/Hr, saturated steam.
4. Density compensated vortex flow meter (Smart transmitter).
5. Support is good and no probs.
6. Density compensation by temperature measurement and steam tables are fed in the processor.
7. Steam trap before meter. Straight lengths 10 and 5 upstream and downstream respectively.
8. a)Check for high turndown and high accuracy meters.
b)Check for filters due to vibration

I can help you if you have any specific questions.

Good Luck,

 

[TBP]

The district heating operating I worked for used vortex shedding meters (with pressure transmitters to compensate for any line pressure fluctuations) for billing purposes. Any meter manufacturers I have dealt with have similar installation requirements for straight lengths of pipe upstream and down, and what basically what amounted to good steam piping practices (sloping, trapping, etc.) Meter sizing is similar to control valve sizing, in that if you have the right sized line for your service, the meter will typically be one pipe size smaller. The steam system operated at 125 PSIG, with the boiler safety valves lifting at 150. The meter bodies were rated for 300 PSIG steam service, and came in either a flanged, or wafer style body to be mounted between class 300 flanges. For larger lines, such as 12", we used an insertion vortex meter, that dropped into the line though a thread-o-let. To get the turndown we required, we reduced the 12" line to 10" for the meter installation, then took it back up to 12" after the specified staight diameters of 10" pipe.

Something that we found, as we retro-fitted new steam meters into our system, was that a large number (as in most) of lines and their existing orifice plate meters were grossly oversized for the steam load. To have a 6" line reduced to 2" for the new meter was pretty common. The percentage of oversized steam installations is HUGE in every industry I've been involved with.