Message Board Thread - "Process heater scanning"

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Process heater scanning PM390 12/29/2009
Hello,
I was wondering if there was anyone in the forum who is in this area of work? I am currently about 4 months into it. I am level 1 certified. I work in a refinery as a Heater Specialist with 2 PM390s. One has a Hughes array which I use with a flame filter for my heater scan mainly. I am having a hard time judging temps/emissivity due to scale buildup, t-reflect, long angles, etc..
I was just wondering if there was anyone here with knowledge in this area and willing to share any tips or recommendations for better analysis.
 
Re:Process heater scanning Infrared Guy 1/5/2010
PM390,
We perform process heater tube surveys on a daily basis. I may be able to offer you some help. Contact me at kenb12@hotmail.com
 
Re:Process heater scanning paulpartin 2/11/2010
I also do heater inspections (learning every time). Look for Ron Luciers procedure for fired heaters. It is posted on this board somewhere (2004-2006?) timeframe. It is a good basis for what to do.
 
Re:Process heater scanning manuel-thermoimagen 2/11/2010

check this threads..
(2006)
http://www.infraredtraining.com/community/boards/thread/325/

(2004)
http://www.infraredtraining.com/community/boards/thread/221/

good luck.


 
Re:Process heater scanning PM390 2/25/2010
Tons of great information here! Also found a Reflectometer for giving you emissivities! I have a copy of Lucier's (almost typed lucifer!) and it seems pretty handy. Although I am doing this pretty blindly as I really have nobody to compare notes with. I have requested more in depth/hands on/one on one/ with one of our IR specialists who travels the globe doing heater reports. As he will be here next week I am anxious to get on the ball with knew knowledge on how IR of heater tubes is supposed to be done!
I can do IR on everything else no problem, but when it comes to heater tubes and the age of our heaters/leagalities if a heater tube failure, I am real hesitant in submitting a report saying the heater 'looks fine', or 'shut it down! you have a hot spot!"
 
Re:Process heater scanning jvoitl 2/26/2010
I would be careful with a reflectometer. Make sure it operates in the same spectral range as your cameras.
 
Re:Process heater scanning ec 2/26/2010
You need 2 parameters to calculate heater tube temperatures - Emissivity and background temperature. If you remember in infrared thermography school, we approximate background temperature by laying down an aluminum foil sheet next to the target. You can apply the same technique inside the heater firebox by using a shiny, polished, very reflective stainless steel sheet. Meanwhile, emissivity is the tricky one due to scale, deposits on the tube surface. You need basically a reference point in the tube surface to calibrate your infrared camera and set your emissivity.
 
Re:Process heater scanning TDLIR 2/28/2010
I have been inspecting furnace tubes for over 15 year. A few years ago I presented a paper of Steam Reformer inspection and talked about reformer tube inspection without the use of temperature to locate tube problems and issues with furnace operation. You can read this paper here at the irinifo.org web site:

http://irinfo.org/articles/2_1_2008_james.html

This January I presented a paper on a case study that I was a part of in order to see how accurate reformer tubes can be measured with an IR camera (PM390)and a proper reference. This paper talks about the major issues, problems and parameters for proper and accurate temperature measurment of reformer or furnace tubes.

It is not just knowing the E and the R it is much much more. And if you have the time and money, you can achieve accuracy to the single digit degrees C as I have.

Best Regards,

Sonny James
 
Re:Process heater scanning TDLIR 2/28/2010
I forgot to mention if you want a copy of this paper you can email me at tdlir@hotmail.com
 
Re:Process heater scanning ec 3/2/2010
You are heavily advertising your tube inspection procedure for a Steam Methane Reformer. The SMR is one of the friendliest heater in a refinery mainly because the tubes are relatively clean, tubes are near or accessible from the inspection ports at all levels of the heater. Also, the tube temperatures and the firebox temperatures are not that far apart such that variations in emissivity will affect tube temperatures slightly. I admire your confidence when you said your tube temperature measurement accuracy is within a single digit.

How about other heaters? Heaters with dirty tubes because of scale and deposits, and huge cylindrical heaters where the tubes are quite a distance from the inspection window. Can you also claim single digit accuracy on these? Do you use any reference to compare your results?
 
Re:Process heater scanning TDLIR 3/2/2010
Sorry In Advance For The Long Reply.

Hi ec, thanks for your comments. You are correct in some and incorrect in others.

Firstly, let me say that heater tube inspection and procedures can be argued upon infinitely. Therefore, I am not going to make this an argument on “My Procedure” to inspect heater tubes.

That being said let me start with your comments and questions:

1. “You are heavily advertising your tube inspection procedure for a Steam Methane Reformer.”

Answer: No. My intent is not to advertise any procedures. My paper explains that I have developed a program to assist plant operators to gain more consistent single point pyrometer reading. This is because; there were no consistency as all were using this type of equipment incorrectly due to no adequate training. As to using Thermography for these reformers, I am not saying that my way is the only way, I am simply explaining what results I have gotten and what I have learnt.

2. “The SMR is one of the friendliest heater in a refinery mainly because the tubes are relatively clean.”

Answer: Friendliest Heater in a Refinery: No. Relatively Clean: Yes. I say no to the friendliest because temperature aside, it is difficult to diagnose problems with reformer heaters as the process is sometimes more complex than a box or cylindrical heater. Temperature is not everything. It is just one part of the inspection. This is what I say in my paper.

3. “tubes are near or accessible from the inspection ports at all levels of the heater”

Answer: Yes you are correct.

4. “the tube temperatures and the firebox temperatures are not that far apart such that variations in emissivity will affect tube temperatures slightly”

Answer: This is not true. Depending on the reformer, Delta-T from Refractory to Tube can be more than 300C. In addition, tube emissivity is Greatly affected by reflected temperature, tube condition, tube temperature, etc… As a person who has used several contact reference standards, I have found that E can vary into the double digits. Industry Rule of Thumb of 0.85 does not hold true.

5. “I admire your confidence when you said your tube temperature measurement accuracy is within a single digit.”

Answer: Thanks! And Yes, with a proper reference, accuracy can be achieved. If you read my paper, you will realize that I do not say what is accurate as this is different for many people. I mention that you are only as accurate as your accepted reference standard. So yes, as compared to a calibrated contact reference standard, I have achieved single digit accuracy.

6. “How about other heaters? Heaters with dirty tubes because of scale and deposits, and huge cylindrical heaters where the tubes are quite a distance from the inspection window. Can you also claim single digit accuracy on these?”

Answer: Again, my papers go to say that one of the most important things to be aware of are the limitations. Every furnace has limitations and thus you must be aware and try to compensate for them. So let’s talk about:

Scale deposit: Depending on the type and thickness of the scale deposit, this issue can be of little or extreme importance to a process engineer. Again, a scale deposit is a limitation. If you identify scale as I do from time to time of other heaters, you have to determine what you can do to overcome this limitation if you can or work around it or with it. Every inspection on a heater has a specific goal. It is not always temperature accuracy. Many times apparent temperatures will work as a guide, but identifying and diagnosing a problem or condition is what many plant engineers want.

Tubes at far Distances: Again, my paper discusses these types of limitations. Be aware and try to compensate, if you cannot then note it in the report.

Can I claim Single Digit for these types of furnaces?: Yes. For the tubes that I can compensate for. Just like any other furnace.

7. Do you use any reference to compare your results?

Answer: Yes whenever I can and it is practical. If I cannot, I report my limitations.

Final Note: Nothing is ever perfect in the field, but the key is to know what the limitations are. Also knowing the process among other things that I mention in my papers. Different heater will demand different procedures. An Inspector must know how to adapt to gain the best results possible. My papers were on Steam Reformers. However, the knowledge and techniques I mentioned can be used to help inspectors with other heaters. It will for the least make them ask question which may lead to better answers. My way is not the only way, but my experience can help someone else. That is why I write these papers. Otherwise, I can be just like many other professional tube inspectors and not tell anyone anything and keep all my knowledge and experience until I die. Who benefits from this? All this does is make it harder for this technology to progress the correct way. I believe in mentoring and teaching, which is why I have devoted my career to this.

I also do not claim to know everything. In fact, I know very little when it comes to the grand scheme of things, as do most of us. However, what I know, I know it well and I am always open to criticism as I learn from this. So thank you for your question, it has made me think some more and has already made me a better thermographer. You are always welcome to come down to my part of the world, I will be more than happy to have more of these great discussions. In fact, I ask that all professional tube inspectors comment and ask questions on my papers. I am the only one in my part of the globe that is qualified to perform these surveys. So I too learn by trial and error and by other who question and mentor. My luxury is that I have dozens of reformers and furnaces in less than a 5-mile radius and all the plants are always happy for me to come in and try something new whenever I think of something. Apart from plant personnel, not much thermographers have this advantage.

Best Regards,

Sonny James
 


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