Experimental Study Of The Motion Characteristics Of Coal And Biomass In The Collision-block-type Low NOx Fuel-rich/Lean Burner

Biomass and coal co-firing power generation is a good method to utilize biomass energy effectively, with low emissions of NOx and CO2. This technology will be widely applied because of the simple technical barriers and the low engineering cost. But the density, shape and composition of biomass particles are different from those of coal particles, which influenced the characteristics of multiphase flow in pneumatic conveying process. So the burners need to change.In this paper, the motion characteristics and the separation performance of two-phase flow is investigated, in the collision-block-type fuel-rich/lean burner which is developed by Zhejiang University. Glass powder (SiO2) particles are used to simulate coal particles, rice husk is chosen as typical biomass. The block heights h=40mm,50mm,60mm are used as the condition variable. Results showed that the different heights of block have obvious influences to the motion characteristics and the separation performance of both glass powder particles and rice husk particles.In the study of the motion characteristics and the separation performance of glass powder particles, an experimental research was conducted in a visual cold experimental setup using a three-component particle-dynamics anemometry (PDA) system. Results showed that the fuel-rich and fuel-lean streams have different velocities after the block, the velocities difference bigger as the block higher. There is an annular recirculation zone after the block. The turbulence intensity is largest in the annular recirculation zone, the turbulence intensity greater as the block higher. At the same time, the collision-block-type fuel-rich/lean burner gave good separation performance, the separate effort more obvious as the block higher, the particle mass ratio of rich and lean flow is1.23,1.83,4.48, as h=40mm,50mm,60mm.In the study of the motion characteristics of rice husk particles, the particle velocity is investigated using a high-speed video camera measurement system. Results showed that the fuel-rich and fuel-lean streams have different velocities after the block, the velocities difference bigger as the block higher. There is also an annular recirculation zone after the block. The annular recirculation zone moved backward and moved up as the block higher, the turbulence intensity greater as the block higher.In the study of the distribution characteristics of rice husk particles in the burner outlet, the separation performance and the particle size distribution characteristics are investigated using a screening and weigh method. Results showed that the collision-block-type fuel-rich/lean burner also gave good separation performance with rice husk particles, the separate effort more obvious as the block higher, the particle mass ratio of rich and lean flow is1.39,1.87,4.19, as h=40mm,50mm,60mm. At the same time, overall speaking, the particle sizes of the fuel-rich streams are bigger than the fuel-lean streams, the trend is more obvious as the block higher.