Numerical simulation of O<sub>2</sub>/CO<sub>2</sub> combustion in large cement precalciner

Abstract

The cement industry is the second largest source of CO2 emissions after the power industry. The greenhouse effect caused by CO2 is increasing nowadays, so CO2 emission reduction is urgent, the cement precalciner kiln O2/CO2 combustion technology has great application value in CO2 emission reduction. This paper selects 3200 t/d TTF cement precalciner as the research object, and Tianhe-2 supercomputer is used to carry out massive parallel CFD numerical simulation. Numerical simulation was used to study on the effects of pulverized coal combustion mixed air with pulverized coal combustion mixed O2/CO2 on velocity field, temperature field, material composition distribution and NO x concentration distribution. The results show that the O2/CO2 combustion technology has similar velocity field distribution and raw material decomposition ratio when compared with the conventional air combustion, and it will not affect the operation of the precalciner. Besides, the over-temperature zone in the precalciner is reduced, the temperature-brushing phenomenon is effectively alleviated, and the NO x concentration at the outlet reduced greatly from 995 to 96 mg/m3, so that the post-treatment De-NO x process can be removed to reduce investments. Furthermore, the nearly pure high-concentration CO2 in the flue gas is easy to be captured and reused, alleviating the greenhouse effect.