Performance Study Of Three Kinds Of Cyclone Separators-angular Entrance、Tapered Outlet And Cylindrical Body Structure

As a highly-efficient clean combustion equipment, the CFB boiler is widely used around the world. With the development of this technology, the CFB boil’s structure must be optimized. A cyclone separator is one of the key equipments of a CFB boil and plays an important role in the operation of a CFB boil. One of the important researches is to improve the separator performance and the compatibility.Based on the requirement of modified boils, this research comes up with three new cyclone separator structures. They are angular entrance, tapered outlet and cylindrical body structure. In this paper, both experimental research and numerical simulation are used to study gas-solid flow characteristics and separator performance of these three new separators. It gives the main study tasks and contributions of this thesis as follows.This research has set up a visual cold cyclone separator experimental bed to do the study on the separator performance of these three new separators and the standard separator. Experimental results show that the cyclone separator with an angular entrance is not beneficial for the separator performance. When the angular entrance’s upward angle is 45° and the downward angle is 30°, the separator performance becomes the lowest. The cyclone separator with a suitable tapered outlet is helpful to improve the separation efficiency. Under the same standard condition, the cylindrical cyclone’s and the cylinder-on-cone cyclone’s separation efficiency are both nearly 96.5%, while their pressure drop are both nearly 1100Pa. They have the same level of the separator performance and the same trend with the influence of the operating conditions and some structure parameters.As for numerical simulation, this research takes advantage of Reynolds stress turbulence model and Euler multi-phase model to do the study on gas-solid flow field and separator performance. As for the flow field, simulation results show that the gas-solid flow field of these three new cyclone separators is similar to the normal one on the whole, but has some differences in local. For example, based on characteristics of the flow field, the cylindrical cyclone is divided into three areas:rotation area mainly for particle separation, transition area for avoiding back-mixing and accumulation area. What’s more, extended research on separator performance of these three new cyclone separators has done using numerical simulation. The results show that, both flow field and separator performance agree well with the experimental data. Increasing angular entrance’s upward angle or downward angle is bad for separator performance. The performance of a cyclone separator with an inverted circular-truncated-cone-shaped exit will be influenced a lot by size. Critical height is discovered for the cylindrical cyclone in this research. Below the critical height, separator performance will sharply decrease with cyclone height decreasing. The value of the critical height is equal to the height of rotation area plus the height of accumulation area.A modified cyclone separator is put forward based on the experimental and simulation study. The results show that, in comparison to the standard separator, under the same standard operation conditions(T=800℃, dp=300 μm, Vi=30 m/s, Ci=2.0 kg/m3), the separation efficiency of this modified real cyclone separator increases by as much as three percentage points, while the pressure drop has a raise about 200 Pa. The separation efficiency is 99.17%, while the pressure drop is 1089 Pa.