Open Access

ARTICLE

Numerical Simulation of Sludge Combustion in TTF Precalciner

by Penghui Wang, Hongtao Kao^*

College of Materials Science and Engineering, Nanjing Tech University, Nanjing, 211816, China

* Corresponding Author: Hongtao Kao. Email:

Journal of Renewable Materials 2021, 9(4), 671-693. https://doi.org/10.32604/jrm.2021.013377

Received 04 August 2020; Accepted 16 September 2020; Issue published 01 February 2021

Abstract

The research method of computational fluid dynamics (CFD) is used to study the technology of burning sludge in cement precalciner. The simulation results show that the flow field in the TTF precalciner is stable, the spray effect is good, and no raw meal collapse occurs. The special structure of the TTF (Trinal-sprayed) precalciner allows the pulverized coal and sludge to fully exchange heat with the flue gas and burn. When there is no sludge burning in the furnace, the decomposition rate can reach 92.1%, and the maximum temperature of the precalciner can reach 1600 K. When the moisture content of the sludge is constant, as the amount of sludge increases, the overall furnace temperature shows a downward trend and the minimum temperature at the precalciner outlet can be reduced to 1080 K. The phenomenon shows that sludge has a great influence on furnace temperature. In order to ensure that the decomposition rate of the raw meal is not less than 85%, the decomposition rate of the raw meal under different conditions is calculated. It was found that the sludge input can be about S-20% when the mositure content of the sludge is 50%. Moreover, when the water content of the sludge is 60%, the burning amount of sludge cannot be higher than S-20%, which ensures the normal decomposition of cement. The addition of sludge reduces the temperature in the precalciner and further inhibits the generation of thermal NO_x. The reduction of CO content produced by incomplete combustion of pulverized coal indicates that CO suppresses the production of fuel-type NO_x. The NO_x concentration at the gooseneck is as low as 522 mg/Nm³. Additionally, it was also found that when the sludge input is fixed, the NO_x concentration decreases with the moisture content of the sludge increasing, indirectly proving the inhibitory effect of H₂O on NO_x.

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