Flare Stack Thermowell

Started by Hawaii596, 03-09-2015 -- 16:19:48

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Hawaii596

03-09-2015 -- 16:19:48
Anyone have vast experience with Flare Stack Thermowells?  Need to spec out good thermocouple type, good sheathing materials for fast temp response time, or any other suggestions as to what type technology temp sensor will hold up to around 2200 F continuous with occasional excursions up to about 2600 F.  Looked into Type C Tungsten/Rhenium, and apparently they won't hold up to the high temperatures.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

metrologygeek

#1
03-12-2015 -- 09:17:37
It seems like you're looking at using a noble metal thermocouple for this range. I'd go with B since it has a higher temperature limit and doesn't require cold junction compensation.

Hawaii596

#2
03-12-2015 -- 17:20:03
Its a l ittle of a convoluted mess.  Without getting into too much internal details, we have done them in R, and B has a theoretically slightly better max temp (go figure: B, R, and S are all Platinum/Rhodium combinations in varying proportions; but I guess the added Rhodium in the second leg slightly improves max temp).  The challenge has been that even with R, these things are used in a Flare Stack which constantly billows 2200 F flames, and in a couple of months, the R thermocouple essentially dissolves.  I have spent quite a lot of time researching, and there aren't many good answers out there.  I can't go into too much detail due to confidentiality.  Just wondering if anyone has worked on Flare Stack Thermowells that could specifically converse about various options.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

dminesinger

#3
03-13-2015 -- 01:36:16
Had a regular customer that was a steel foundry. They had to replace their T/C about every other month. Sound like what you are going to have to do.
PapaBear

*'It's the Veteran, not the reporter who has given us the freedom of the press.'
'It's the Veteran, not the poet, who has given us the freedom of speech.'
''It's the Military who salutes the flag, who serves beneath the flag, and whose coffin is draped by the flag, who allows the protester to burn the flag.'

Hawaii596

#4
03-13-2015 -- 08:41:20
As alluded to, that's about the size of it.  And as mentioned, I can't go into detail here.  But what my research has been telling me is that everyone is going to infrared - there are some pieces of IR thermometry hardware made just for such applications.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883
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