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The development of magnox fuel cans at the Heston Laboratories of A.P.C. Ltd. required a non-contact method of measuring fuel can temperature during heat transfer tests. Infra-red techniques were examined and a two colour ratio pyrometer was selected as offering the greatest prospect of success. A design specification was compiled for an instrument having a lower temperature limit of 250°C with a target area of approximately 1mm². During heat transfer tests a pressurised rig is used and an observation window is necessary. This leads to some deterioration in performance which it is impracticable to remove by internal chopping and the pyrometer is designed for outside use. Operational wavebands around 1.8 and 2.3 microns are chosen and a lead sulphide infra-red detector operating at room temperature is selected. The properties of the detector lead to a design where the signal is chopped at 900 cps and modulated at 30 cps by the energy in each waveband. Conventional optical systems are considered and rejected in view of the large size of chopper wheel necessary. An alternative system is devised in which a commercially available pencil galvanometer is used to combine the function of chopping at both 900 cps and 30 cps. This enables an optical system to be designed which, because it employs reflecting optics, is compact and for the most part axially symmetric. The signal ration is extracted using an automatic gain control technique and a high signal to noise ratio is achieved with a phase sensitive rectifier at the output. The pulses which activate the galvanometer chopper and phase sensitive circuits are derived from a master oscillator operating at 900 cps. The performance of the system is assessed and it meets the specification in all respects except for a small surface geometry effect. The underlying cause for this is examined and a means for overcoming it is suggested. The performance when scanning a magnox can during bench tests is illustrated and it can be seen that although agreement to within 2°C is obtained with thermocouples placed at the fin roots, the geometry effect prevents the isolation of fin tip temperature. During the development of the instrument the possibility of wider application was an important consideration. Some of the applications which have arisen are discussed briefly and an indication of the performance of the pyrometer is given. Furthermore the system is capable of easy modification for use with a cooled detector and other regions of the infra-red spectrum.

This project focuses on the numerical modeling of a rotary kiln pyrolyzer such as found in the e.g. WoodRoll multistage gasification process. The model consists of two parts: a granular flow model, and a pyrolyzer model. In the first part, Saeman's equation was employed to develop a model which can describe the behavior of solid granular flow in a rotary kiln without reaction. Residence-time distribution (RTD) is the main aim to study in this part, which was simulated by axial dispersion model (ADM). The model requires only one fitting parameter that is dispersion coefficient (Dax), which was studied in parallel by two cases: constant value of Dax, and Dax as a function of kiln's length. The result of both models show good predictable in comparison to experimental data from literature, and represent narrow distribution of residence times that behave similar to plug flow reactor. Unfortunately, the result still cannot claim which model of Dax is the best model to describe RTD in rotary drum. The second part of the thesis purpose to design the model of rotary kiln pyrolyzer, which contains specific behavior of granular flow, heat transport in a kiln, and primary pyrolysis of wood. The model of steady-state condition with constant wall temperature was simulated to generate temperature profile and conversion along a kiln. This model included all heat transport features such as conduction, convection, and radiation. According to the result, supplied energy from outer surface of the kiln essentially transfer through the kiln via heat conduction, which occur between solid bed and rotating surface of the kiln. Temperature profile that generated by this model looks reasonable to the process of rotary kiln pyrolyzer, which affected by heating system and heat of reaction along the kiln. The result also demonstrated that conversion of wood is strongly dependent of wall temperature or heating rate of the system. Nonetheless, kinetics data for wood pyrolysis still a debatable issue in many research, and this model required validation by experiment of rotary kiln pyrolyzer.

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