Javed, Reformer tube skin temperature monitoring by Optical pyrometer - both by operational and inspection personnel - is an accepted industry practice / system (built-in) in most of the refining, petro chemical, fertilizer industries for over 5-6 decades. For Topsoe side fired furnaces, tube skin monitoring thru each peep hole and side hole windows at different floor levels (for each furnace) is also an accepted industry method or system. This is done by Operations group in three shifts. Inspection group cross-checks the readings with an independent pyrometer once in 15-30 days depending on the errors in operational readings and hot spots seen in furnace tybe skin monitoring. Also it is an accepted system or standard that both pyrometers (operations and Inspection group pyrometers) are calibrated with a independent and different calibration type pyrometer to check the accuracy in both pyrometers to apply correction factors or errors that are likely to crop between different operating personnel and inspection personnel. This is usually done once in 3-6 months. Thermoscan studies are also done (as a compliment not as a substitute) in recent years say during the last 6-10 years by some refiniries, petro chemical plants with an emissivity factor of 0.90 - 0.95 is usuall applied for furnace tube skin temperature. Thermo scan is done usually as a compliment (not a total subsitute) to routine optical pyrometer measurements (done on three shift basis by operational personnel in a running refinery, petro chemical or fertilizer plant). Purchase of a new pyrometer and thermo scan is dictated by several considerations (cost, accuracy, service, spare parts availability, reliability, trouble free use etc). Discussion forum cannot give any specific view on this. Trust this help you C.V.Srinivasan Nishi Engineers Pvt Ltd India April 22, 2007 E-mail: nishi@vsnl.com >hi all of you > >i m new to this forum... >the dilemma i m facing is not new...instead it must have >been discussed time and again.... > >we at our refinery have a haldor topsoe A/S designed side >fired terraced wall hydrogen reformer (capacity--38000 >MTPY)having 150 tubes housed in two furnace chambers equally >(75 in each fire box and in a single line).tubes are made of >paralloy HM39WM cast alloy. > >for regular measurement of tube skin temperature we have >been using minolta/land cyclops optical pyrometer (spectral >range of 0.8 to 1.1 um ) while assuming an emmisivity of >0.90 > >recently our process department which monitors tube metal >temperature have decided to go for another model of >minolta/land cyclops i.e. furnacepro having a narrow band >spectral range of 3.9 um.which is well and fine. >on the other hand our deparment(inspection) is looking at >the possibility of acquiring a thermography camera .we had a >demo of the flir system P50F THERMACAM (SR--3.9 >um)recently.during those measurements emissivity was taken >to be 0.9. > >as is quite well documented optical pyrometer readings need >to be corrected to get actual tube skin temperature .in this >scenario i wish to know how acurate will a thermacam will be >& how much should i consider my tube metal emissivity to >be.do i need a detailed one time survey for emissivity >measurement using contact type pyrometer. > >please advise