Message Board Thread - "Thermography of tube skin temperature of Furnace tubes-- Solution needed"

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Thermography of tube skin temperature of Furnace tubes-- Solution needed Sanjib 8/21/2005

We intend to procure an infrared thermal imager for our oil refinery process heaters. Before finalising the technical specifications,can any body help us on the following?

1)What type of camera would be the best for this application? can you tell the suitable wavelength range?

2)Can we go for a long range camera(7-14 um) with flame filter at 10.6um, as is done in FLIR Thermacam P65? does it give good results? any body having any experience on this? Is it essential that we should go for SW/MW camera..What about LW camera with uncooled microbolometer technology like P65?

3)Which models( make also)would be best for this application?

Already we have seen demostration of a few cameras. But, all are showing quite high values of the skin temperature( than actually is) when viewed through the flame,reason being the interference of flame. Pl. suggest me the regarding the latest models and companies that give really good results...

 
Re:Thermography of tube skin temperature of Furnace tubes-- Solution needed Azar 8/22/2005
FLIR has introduced a new camera for furnace/heater tube inspections.

The camera is ideally suited for such work utilizing a 3.9 micron flame filter. The images are crisp and clear. Accuracy is an impressive +-2% of reading. The camera will sell for <$40K.

For a demonstration please contact your local FLIR representive or call 1-800-GO-INFRA (1-800-464-6372).
 
Re:Thermography of tube skin temperature of Furnace tubes-- Solution needed Doctir bob 8/22/2005
Some work that I did at a electric power generating station for EPRI in 1995 provides some very useful information for this application. We measured the spectral transmittance across 36 feet of gas flame in this boiler. As shown in the accompanying figure, the peak transmission occurs at 3.9 micrometers. While there is another, lesser peak, near 10.1 micrometers, it has about 1/3 the transmittance, and is not preferred.
 
Re:Thermography of tube skin temperature of Furnace tubes-- Solution needed TDLIR 8/25/2005
As you can see from the last 2 replies you got from Azar and Doctir bob, you now know that the answers to your questions are:

1- SW/MW wavelength camera with a 3.9 micron filter

2- Going LW is not advised as the transmission percentage is much too low (approx 30%). That is true for even the uncooled microbolometer. But as you can see FLIR now has an uncooled SW/MW microbolometer for this application only.

3- Currently, the best-proven models of cameras right now are the PM390 and 550 SW/MW cooled systems.

With regards to your remarks about the demonstrations done at you plant and getting higher temperature values... I do not know which cameras were demonstrated to you, but you must also take into consideration that without proper Background, Emissivity and Distance corrections, you temperatures will most definitely be way off. The higher you go in temperature, the larger the degree of error. So therefore a small variation in Emissivity will have a big effect on your temperatures. And wrong background settings will also affect you temperature accuracy. And distance will affect your spot size, so small diameter tubes at far distances may not be accurately measured.

You must establish references that you can use to calibrate and adjust your IR camera to. Without these references you are simply making uneducated guesses on temperature. Many thermographers and professionals all have their own preferences of references, such as Gold Cup pyrometers, Test Coupons, Contact Thermocouples, embedded thermocouples, etc…

My recommendation is whatever satisfies your needs for what is an accurate reference for your application is good enough. Remember that you can only be as accurate as your reference.

Know your limitations and try to work around them in whatever way you can.

Hope this helps.

Regards
Sonny James
www.tdlir.com
 
Re:Thermography of tube skin temperature of Furnace tubes-- Solution needed jack1970 7/25/2011
Doctir bob wrote:
rk that I did at a electric power generating station for EPRI in 1995 provides some very useful information for this application. We measured the spectral transmittance across 36 feet of gas flame in this boiler. As shown in the accompanying figure, the peak transmission occurs at 3.9 micrometers. While there is another, lesser peak, near 10.1 micrometers, it has about 1/3 the transmittance, and is not preferred.
hi,

i have noted that in you graph of a transmission spectra of a gas fired boiler, you go only down to 2um. Just wondering what is the transmission spectral below 2um.

Jack
 
Re:Thermography of tube skin temperature of Furnace tubes-- Solution needed USMC4me 7/25/2011
A lot of Thermographers haven't performed thermal scans on furnace/boiler tubes before. This type of inspection should be performed by an experienced fire heated process inspector. One of the main reasons is being able to identify the proper emissivity level and background temperatures.
As far as equipment is concerned, one of the most reliable cameras is the PM390. This is what I have been using for quite some time and it is pretty accurate within the plus or minus 2% ratio.
I work for ACUREN Inspection, inc. out of the LaPorte, Texas office. We travel across the U.S. performing this type of inspection on a routine basis for several clients. If you would like to email me I will reply with all of my contact info so we can discuss this further. My email address is jmsmith@ACUREN.com.
Thanks
John
 


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