Open Discussion Forum Question 4

4. We are operating ethylene cracking furnaces of Selas and Lummus design. One of the important operating parameter is to restrict the tube metal temperature within metallurgical limits. For this purpose operators are required to record the tube temperatures by using optical pyrometers and recording it manually on a log sheet. To reduce the element of human error and omission, we would like to introduce some kind of data logging system which automatically records the temperature when the operator points it a tube and the readings could be afterward uploaded on a PC for analysis / corrective action. Appreciate if any one on the forum suggest any equipment, preferably tested one or any other idea to eliminate fudged reading from the log sheet.  (Asian Ethylene Producer - 12 Dec 2003)

Comment from Texas Ethylene Producer

Presently good quality optical pyrometers using laser technology are available. These are used to measure TMTs in the field and simultaneously record the information, store and retrieve. Many different varieties of them can be seen in the internet under Preferably you should look for laser pyrometer with ability to automatically correct emissivity, preferably emmisivity correction +_2 deg C. These laser pyrometers come with capability to record and store data both as analog or digital form. These data are retrievable and can be interfaced to PC. 1milli second data acquisition rate in the range of 600 ~1500 deg C are available. The laser pyrometer can be used to shoot the TMTs in the field on regular basis and down loaded to a data historian. Regular check of these values wills not only safeguards the tubes from overheating beyond the tube allowable maximum temperature but also indicate time for the furnace decoke.