how can we measure the temperature inside an enclosed shell having temp.at the tune of 800*C & corrosive env.?

Question

Actually it is a huge steel shell, having burning Coal inside, I have to measure the temp. into this shell at the same time there should not be any leakage..

Answer 1

At this temperature, the usual way to measure it would be a radiation pyrometer. But that means you do need a small hole in the shell, so that the pyrometer can "see" the inside.

It might be possible to have a tungsten filament inside the shell. Measuring the resistance of the filament would indicate the temperature; resistance is nearly proportional to absolute temperature. You would also need some kind of sealed, electrically insulated feed-throughs for the filament.

edit added:
I agree that Nita's (the 2nd answerer) solution is much easier than mine.

Answer 2

Almost any thermocouple or RTD sensor will do it. You must somehow penetrate the cylinder, so you can submerge the tip of the thermocouple in to whatever you are trying to measure. Thermocouple is connected with the external instrument which is calibrated tom show temperature. Omega Engineering has excellent catalog on line with everything you can possibly need to measure temperature and more. http://www.omega.com/

Answer 3

There are digital sensors available. Through the thermowell on the reactor insert a suitable alloy probe. Normally hastealloy B should be fine. Alternatively you can use the MOC of the shell itself. Connect it to a pre-calibrated sensor and from the display record the temperatures.

Answer 4

Check Watlow, install a 316 stainless or hasteloy thermocouple well with a Type J Iron Constantan thermocouple lead, to a digital readout.

Answer 5

Measuring the temperature of the outside of the metal. Look up the heat conductivity of the said metal and you should be able to come up with the answer. The other answer would be very expensive.
Ni