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Show 1. Introduction. In this paper we describe the design of a 2-color intrusive pyrometer used to measure particle temperatures at "point" locations in "large" coal-water fuel (CWF) flames. In this context,. "large" is a combustion chamber volume of 2'x2'xlO' (0.6xO.6x3m; about 106 cc); and the "point" radiating source defined by the movable probe is a volwne of about 5 cc. The principal measurements have already been reported [1], but not the details of the 2-C pyrometer design; this is the focus of this paper. Much of the design is conventional and has been reported recently [2] in a description of the device used in smaller flames (of 15 cm path length across the furnace); what is unique in . . the application to the larger furnace is the design of the tip of the probe used to pick up the radiation signal. The context of this problem is the need for measurement of particle temperatures in p.c. flames where gas and particle temperatures may be different, and conventional suction pyrometer or venturi-pneumatic measurements provide values that are generally considered to be averages of the gas and particles or, more probably, are values strongly biassed to the ambient gas temperatures. This is also true of ultra-fine, fast-response (sapphire) optical fibers where the temperature of the fiber tip is measured (optically). The natural alternatives, of 2-color or other optical measurements, can have the advantage of being non-intrusive; however, the value obtained is then generally a measurement of the average temperatures across the viewing volume. Consequently, intrusive detennination of the radiating volume would appear to be a necessary component of any optical design for "point" measurements, and this design aspect is the component that is believed to be unique at this time in the design described here. The design would also appear to be not limited by further increase in flame size. 2. Probe Design. The principle of the probe design is conventional. It is a variant of a device developed by Macek and Bulik [3] for measurements in fluids beds, and the variant used in these studies is described in some detail elsewhere [2]; following is a swnmary. A radiation signal is captured in an optic fiber; the signal is then split into two, passed through filters at two different wavelengths (800 and 1000 run), and transmitted 2 |