Experimental Study on the Circulating Characteristics of the Return Particles in CFB and the Validity of the Particles to Desulphurization

The cold-model experimental system that particles flow from the top of CFB reactor is set up to study the circulating characteristics of the particles in the reactor. In order to get further information about the particles distribution and interaction with air flow, the two-phase gas-particle flow and particle concentration in the tower are studied with the use of phase-Doppler particle dynamic analyzer (PDA) system. The effects of the operating parameters including the mass flow rate and the superficial gas velocity on the process of the particles return to the main flow were investigated. The definition of valid internal circulation is put forward in this paper to describe the contribution of the particle to the SO₂ removal reaction. The results showed that the concentration distribution tends to be right high and left low in the radial direction. In axial, more particles concentrated in the upper of the reactor, especially in the case of high superficial gas velocity. With the decrease of the superficial gas velocity, the maximum fallback length of particle and the average particle concentration increase quickly. While the valid particle concentration increases slowly. The quantity of valid particles increases a little. Sending the particle from the top of the reactor has little contribution to the SO₂ removal reaction.