Jia-bing Wang*, Takeshi Tsunemi*, Takashi Fujii* and Muneharu Ichikawa**

*R & D Center, Osaka Gas Co., Ltd.,
**Osaka Gas Eng. Co., Ltd.,

+ Correspondence should be addressed to Jia-bing Wang:
R & D Center, Osaka Gas Co., Ltd.,
(6-chome, Konohana-ku, Osaka 554 Japan)

Abstract

A mathematical model is presented to compute the behavior of fluid flow, heat- and mass-transfer in a dried sewage sludge melting furnace using a coke-packed bed. A system of equations describing the conservation of mass, momentum and enthalpy is used to simulate the transport phenomena. Finite volume method is used to solve the system of coupled non-linear partial differential equations on the gas phase and coke particles. For the dried sludge particles, a set of ordinary differential equations is solved using Lagrange method for computing the particle trajectories. The numerical predictions are in reasonable agreement with the measurements obtained by a bench-scale melting furnace. The influence of process operating variables such as swirl velocity, as well as combustion characteristics of the dried sluge, on the coke consumption of melting furnace is studied using a field modeling technique. The principal conclusion reached from this study is that upgrading of this melting furnace can be achieved with modifications of size distribution and composition of the dried sludge, together with the optimization of process operating variables. This model is applied effectively as an engineering tool for designing the furnace and improving the performance of furnace in operation.

Key words: simulation model, dried sludge melting, coke combustion, packed bed, three-fluid model