Hydrodynamic Similarity In Dense Transport Bed

Pressurized pulverized coal dense transport bed gasification technology is an important development of IGCC technology selection and polygeneration. However, dense-phase transport bed has features different from the other reactor, of which gas-solid flow behavior is very complex. By conducting a study of hydrodynamic similarity, people could provide a reference for reactor design and scale up. Study of hydrodynamic similarity has been more directed to bubbling and fast fluidization, but gas solid flow in the riser of dense transport bed belong to dense suspension upflow, which is significantly different from other flow patterns, so it is required for study of hydrodynamic similarity of gas solid flow in dense phase transport bed, analyzing applied similar criteria, conducting extensive validation experiments and modelling its validity.1. Using the method of dimensional analysis, from the basic flow equation, obtained similar criteria applied to solid flow dense suspension upflow and moving bed. Wherein, Ar is affecting the number of gas-solid phases of important physical parameters of the force, conducting experiments should first select the same or similar physical condition Ar number, and then design the appropriate action depending on the flow riser and riser of similarity criteria condition.2. Suitable solid particles and gas was selected due to similar criteria for flow experiments. In a wide operating range of the riser, flow behavior of Geldart Class B sand particles was studied. Under conditions of high solids circulation rate, solid volume concentration of the fully developed can be more than 0.07. Since the gas expansion in the axial direction for acceleration, the profile of solids holdups is not the typical S-shaped distribution of the fast fluidization conditions. When selecting the same or similar number of similarity criteria obtained, the solid holdups and solid velocity presents a similar distribution. The experimental data and theoretical analysis combined to give rise for compute-intensive suspension stream flow model parameter distribution. Established a riser model based on force decomposition method of solid flow, calculation rerults of riser pressure drop and experimental results are in good agreement.3. Based on the empirical relationship of non-fluidized gas-solid flow, combined with dense transport bed downcomer flow characteristics, established of gas-solid flow model has been negative pressure differential moving bed. Standpipe axial pressure distribution and the distribution of voidage are calculated by the model with the theoretical analysis. Since there are differences between the arrangement of the ideal state physical parameters and the experimental apparatus experimental, material aeration position, when the experiment actually pass into the loose merry is larger than the calculated value. According to the similarity criterion, calculated voidage and pressure gradient of different materials under different operating conditions distribution, results show that the downcomer moving bed of solid flow acted similarity.4. Place the riser and downcomer model combined system pressure balance analysis. Established a system pressure balance model that can accurately predict the system solid circulation rate, and distribution of the solids concentration within the riser can be described well. Through further analysis of system, increasing the diameter ratio of the riser and downcomer are conducive to the riser solid circulation rate and solid holdups increased.