Abstract: A 3D mathematical model of flow， combustion and radiation heat transfer was established to study the combustion performance of calcium carbide furnace off-gas(CCFG)in the combustion chamber and to investigate the impact on combustion from different excess air coefficient. It is found that the flue gas from CCFG burning is blocked by a baffle wall and forms a big vortex， thus the high temperature zone is inside the baffle wall. With the increase of excess air coefficient， the fuel conversion degree becomes larger， but even if the excess air coefficient was up to 1.3， there remained CO in the combustion chamber exit， i.e.， a small amount of fuel will burn out in the kiln chamber. As the excess air coefficient increases， the average temperature of gas increases first and then decreases at the exit of combustion chamber.

Key words: twin burn annular shaft kiln, combustion chamber, calcium carbide furnace off-gas, combustion performance, numerical simulation