A mathematical model was developed to describe the gasification of biomass in a fluid-bed reactor. The model was simplified, applied to the gasification of feedlot manwe, and a preliminary attempt was made to compute the gas composition and yields of gas, liquid, and solid products assumlng that the water-gas shift reaction was the only gas-phase reaction. The governing equations were solved by using a soltware Interface. Althu& the predicted and experimental values agreed reasonably well, the comparkon suggested that cracking and reforming reactions involving the volatiis produced during devolatitlzation should be included in the model. An approximate calculation of the gas yields and liquid yields incorporating the thermal cracking reactions of the heavy volatlles compared more favorably with the data.

A model has been proposed for the condition of incipient fluidization in a centrifugal fluidized bed. The model is based on the balance between the overall forces, including the centrifugal and fluid frictional forces, exerted on the fluidized particles and the overall effective weight of the particles. Equations have been derived from the model for predicting the critical fluidizing velocity and the maximum pressure differential (or pressure drop) through the centrifugal bed. A series of experiments was carried out with different solid particles, bed rotational speeds, and bed heights. The resultant data for the critical fluidizing velocity and the maximum pressure drop of the bed indicate that the proposed model is valid and the derived equations are of practical 11s". SCOPEFluidized beds have many advantages as gas-solid contactors. For example, mass and heat are transferred rapidly in the beds and, therefore, temperature and concentration can be maintained uniformly throughout the beds. In addition, solids may be added or removed during operation, which renders continuous operation possible. Thus fluidization technology has been employed extensively in process industries. However, the application of a fluidized bed can be limited, sometimes, by the necessity of pumping a large volume of fluidizing medium through it. This can cause violent slugging or lifting of the fluidized particles out of the bed, thereby creating difficulties in using fluidized beds in industrial applications such as coal combustion, filtration of dusty air, flue gas desulfurization, and solids drying. Recently, the use of centrifugal fluidized beds has received much attention for application in these areas (see, e.g., Gal et al., 1982; Kroger et al., 1979 Kroger et al., ,1980 In a centrifugal fluidized bed, particles are fluidized in the centrifugal field. The bed usually consists of a cylindrical basket that rotates,about its axis of symmetry; the rotation of the axis causes the particles in the basket to form an annular region at the circumference of the basket. Fluid is injected inward through the porous surface of the basket wall, and the particles begin to fluidize when the force exerted by the fluidizing medium becomes equal to the effective weight of particles in the centrifugal field (Takahashi et al., 1984).Features of the centrifugal fluidized bed, especially its advantages over the columnar fluidized bed in gravitational field, are discussed below.The centrifugal fluidized bed can be operated in much wider ranges of conditions than the columnar fluidized bed. In the centrifugal fluidized bed, radial acceleration can be enhanced over the gravitational acceleration, g, by changing the rotational speed of the basket that permits a much larger flow rate per unit area of the distributor than is possible in the columnar fluidized bed, which operates only against the force of gravity.2. The centrifugal fluidized bed can be used for a variety of process operations in systems outside the gravitational field or in systems in rocking mo...

Technology evaluation has been increasingly important because of the pressing needs of new product introduction in a competitive global market. To select the most appropriate technology, a firm needs to have a robust technology evaluation framework to evaluate several technology candidates based on multiple criteria and evaluated by multiple experts. Thus, this paper presents an integrated model for evaluating various technologies for New Product Development (NPD). A network that takes into account the benefits, opportunities, costs, and risks (BOCR) aspects of different technologies is constructed first, and interpretive structural modeling (ISM) is applied next to determine the interrelationships among the factors. Finally, fuzzy analytic network process (FANP) is used to facilitate the evaluation process of decision makers under an uncertain environment with interrelated factors. The proposed model is applied in a flat panel manufacturer in selecting the most suitable panel technology.

This paper describes an investigation of the determination of the heat transfer coe cient at the workpiece±die interface for the forging process. A surface thermocouple has been constructed to measure the temperature at the die surface, where a high pressure occurs, for the simple upsetting forging process. The process was also simulated by a commercial ®nite element package. The measured and predicted temperatures were then used in an inverse algorithm with an iterative approach to determine the interface heat transfer coe cient (IHTC). The results show that the predicted temperatures modelled by a constant IHTC at the rest-on-die stage were in good agreement with the experimental measurement. However, for the forging stage, the IHTC values vary signi®cantly during the process. This has important consequences in the implementation of simulation software.

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