Uniflow Cyclone Research Articles

Pressure Loss and Separation Characteristics Calculation of a Uniflow Cyclone with a CFD Method

CFD simulations of separation devices are frequently carried out with simple models and boundary conditions due to cost and processing time limitations. In the present paper, calculations of pressure loss and separation efficiency of an uniflow cyclone have been performed on the basis of CFD simulations and compared with experimental data. It is shown that simplifications often made to reduce the computing effort significantly limit the prediction quality.

Application of mechanical similarity laws to the collection efficiencies of geometrically types of uni-flow cyclone dust collectors

From the mechanical similarity point of view, the centrifugal effect, Λr, and the Stokes number,St, as well as the Reynolds number,Rec for the motion of solid particles in the cyclone are the relevant parameters. In order to apply these similarity laws for the prediction of the characteristics of the collection efficiency,ηc, geometrically similar types of uni-flow cyclones were used. The body diameters of the cyclones wereD1=30,50,69 and 99 mm, respectively. The feed particle concentration of the fly-ash particles was up toCo=60 g/m3. From the experimental results: (1) the pressure drop, Δpc, in the cyclones was a function of not only the Reynods number,Rec, but also the body diameter,D1; (2) the collection efficiency,ηc, did not always increase with decreasing body diameter but there existed an optimal body size; (3) application of the mechanical similarity laws to the collection efficiency was not always sufficient for estimating the collection efficiency, since the feed particle concentration was an additional important factor; (4) a new parameter which was the ratio,Epf, of the apparent separation energy,Wp, of the solid particles to the energy loss,Ec, of the gas flow in the cyclone was introduced for discussing the collection efficiency; (5) Fuchs theory, used to estimate the collection efficiency, was examined. Fuchs theory may be applied for high feed particle concentration.

Study of the gas circulation patterns in a uniflow cyclone

AbstractA uniflow cyclone is being studied to achieve the separation of hot solids from the gaseous products of ultra‐rapid fluidized (URF) processes. An experimental method with hot wire probes was developed to study the gas flow around the gas outlet, where the solids exit. The vortex penetration in the solids exit could be determined. The presence of solids greatly reduced the vortex penetration in the uniflow cyclone. Restricting gas circulation around the gas outlet dramatically impaired the cyclone collection efficiency. Therefore, good cyclone performance requires a proper design below the gas outlet.

Uniflow cyclone efficiency study

A 0.05-m diameter uniflow cyclone, developed for the ultra-rapid fluidized reactor (URF) process, has been tested under cold modeling conditions at inlet velocities ranging from 9 to 31 m/s and solid loadings ranging from 1.0 to 6.0 wt. solids/wt.gas. The separation length was varied from 1.0 to 10.5 cyclone diameters. Glass beads with a Sauter mean diameter of 29 μm were used. Interferences in the inlet region greatly impaired the solids separation at short separation lengths. They were successfully eliminated by inserting a downward helical roof in the inlet region. Excellent collection efficiencies (over 99.99%) were thus achieved. When the separation length was increased, the vortex intensity in the gas exit region was reduced and the collection efficiency dramatically decreased.

Study of a novel uniflow cyclone design

AbstractA 5 cm diameter scale‐down model of a new uniflow cyclone for the ultra‐rapid fluidized (URF) reactor with a gas residence time under 20 milliseconds has been tested at high solids loading (5/1 wt. solids/wt. gas) under cold modeling conditions. The body length, gas exit diameter and amount of gas withdrawn with the existing solids (gas underflow) were varied to obtain high separation efficiency (over 99.9%). Silica sand of 55 and 105 micrometer Sauter mean diameter was used. Grade efficiency curves were determined for several specific configurations to get a deeper understanding of the mechanisms influencing the separation.

On the Characteristics of a Uniflow Cyclone Type Classifier (2nd Report)

On the Characteristics of a Uniflow Cyclone Type Classifier (2nd Report)

On the Characteristics of a Uniflow Cyclone Type Classifier (3rd Report)

On the Characteristics of a Uniflow Cyclone Type Classifier (3rd Report)

On the Characteristics of a Uniflow Cyclone Type Classifier (1st Report)

Hitherto, many attempts to use an ordinary cyclone as a sieve for the classification of coarse and fine dust particles are found failure, as many fine particles will be separated with in the coarse. Our newly designed cyclone type classifier consists of the multistage upside down type cyclone using the air separating method by the upward air current and connecting in series to an ordinary type cyclone. Air borne feed is introduced in the upward direction into the multistage cyclone inlet. Here, the air current is changed to the whirl by the guide vanes so as to produce a cyclonic whirl. The tangential velocity of the rising air whirl increases, the dia. of inner exhaust pipe decreases. The coarse particles separate out into the lower separating chamber, while the finer particles collect into the individual upper chamber according to their sizes, and the finest is carried away in the outgoing air to ordinary type cyclone. Tests were carried out using the various kinds of dust particles, but in this paper, we present a test result concerning to the cement powder which is passed through a sieve of 200 mesh Tyler standard screen. To analize the sizing of the classified dust particle, we offered a new separating and classifing charactreistic curve instead of the weight frequency curve of the dust particle.