DYNAMIC MODELING OF A TUNNEL KILN

In this article the dynamic model of a tunnel kiln is developed in det ail, based on the transient heat conduction occurring in the products (or wares) and in the lining bricks of kiln cars (LBKC), as well as on the gas continuity, heat balance, and material balance equations. The computational method used to solve the present model is discussed bri efly. Numerical simulations associated with a 72-m-long tunnel kiln th at is used for firing clay bricks were performed Transient heat conduc tion in two dimensions in wares and in LBKC were computed. Two oxygen schedules under one firing schedule and three lining brick structures were simulated. The fuel consumption and flow rates of primary air, co oling air, and exhaust flow were investigated under different atmosphe re (i. e., oxygen concentration) schedules. The relationship between t he fuel consumption and heat storage rate in wares and in LBKC was als o studied. The results of the present numerical simulations show that, using the present model, we can predict the following parameters. tem perature distributions in wares and in lining bricks and in metal part s of kiln cars; fuel consumption; heat losses; heat storage and heat s torage rates in wares, in lining bricks, and in metal parts of kiln ca rs; gas flow; and exhaust components. The present results disclose tha t the dynamic characteristic of a tunnel kiln is dominated by the tran sient heat conduction in wares and in lining bricks. This transient fe ature determines the tunnel kiln behavior, such as fuel consumption, c ooling air flow, exhaust flow, heat storage and heat loss, etc. The re sults obtained are in good agreement with the practical situation. Fro m the present simulations two types of energy-saving structures of kil n cars are suggested.