Cyclones separation factor

Equipment Selection Criteria and Guidelines A number of factors should be considered in order to determine when to select a blowdown drum, cyclone separator, or quench tank to handle a multiphase stream from a relief device. Among these are the plot plan space available, the operating limitations of each type, and the physicochemical properties of the stream. 

Cyclone separators are extremely important to the successful operation of the cat cracker. Their performance can impact several factors, including the additional cost of fresh catalyst, extra turnaround maintenance costs, allowable limits on emission of the particulates, incremental energy recovery in the wet gas compressor, and hot gas expander. 

Six-tenths factor, 47 Yearly cost indices, 47 Critical flow, safety-relief, 438 Back pressure, 440 Sonic flow, 438 Critical flow, see Sonic Cyclone separators, 259-269 Design, 260-265 Efficiency chart, 263 Hydroclones, 265-267 Pressure drop, 263, 264 Scrubber, 269 Webre design, 265 Deflagration venting nomographs,... 

The effectiveness of a cyclone separator depends upon its size and the size of particles to be removed. The smaller the outer shell the more effective the separation conversely, the smaller the particle the greater the separating force required to move it from the air stream to the outer wall. The importance of cyclone size is evident from a consideration of the separation factor discussed in Chapter 2, Eq (2-46). If denotes the separation factor we have... 

As to the distance traveled by the particles themselves, it is obvious that this varies directly as the diameter. Since the separation factor varies inversely as the diameter, we see that large cyclones are less effective in handling fine particles than would be expected from consideration of the separating factors alone. 

Air carrying particles of density 1800 kg/m and an average diameter of 20 pm enters a cyclone at a linear velocity of 18m/s. The diameter of the cyclone is 600 mm. (a) What is the approximate separation factor for this cyclone b) What fraction of the particles would be removed from the gas stream ... 

What forces act on a particle inside a cyclone separator What factors govern the magnitudes of each of these forces ... 

However, there are factors complicating spreading mud process of scrubbers. Despite observed rough expansion of scopes of wet clearing of gas, there is no data about full replacement of equipment with them (cyclone separators, wet filters, scrubbers, etc.) at least in one of the industries (Aliev, 1986 Belov, 1991 and Kolesnik, 1986). 

Both the models of Smolik and Zenz predict cyclone separation efficiency as a function of loading purely from knowledge of the efficiency at low loading and the loading itself. Physical and operational factors, such as cyclone geometry and size, solids size distribution and density, inlet velocity and other operating conditions, are not included in these models, and the effect of these parameters is thus not thought to be of primary importance. In the Muschelknautz model, on the other hand, the inlet velocity, the cyclone dimensions, and the mean size and density of the inlet solids all feature. 

Figure 13.7.3 shows the raw efficiency data plotted against superficial air velocity in the cyclones. The fact that the efficiency reduces with increasing gas velocity confirms that re-entrainment, and not separation efficiency of the incoming droplets, is the factor limiting the cyclone separation efficiency. 

Since cyclones rely on centrifugal force to separate particulates from the air or gas stream, particle mass is the dominant factor that controls efficiency. For particulates with high densities (e.g., ferrous oxides), cyclones can achieve 99 per cent or better removal efficiencies, regardless of particle size. Lighter particles (e.g., tow or flake) dramatically reduce cyclone efficiency. 

In practice, so-called overspray occurs this characterizes the non-deposited liquid drops. In the model, a factor kos considers the overspray, as a ratio of the mass flux of the overspray and the injected solid mass flux. The efficiency of the separator (filter, cyclone) is considered by a factor ksep, which describes the ratio of the re-fed mass flux to the granulator to the fed mass flux into the separator. The factor kgrowth describes the ratio of the mass flux which comes from the separator and is used for the layering and growth (continuous phase) and the mass flux which comes from the separator (dust) and is used as new internal seeds (disperse phase). 

As an example - to produce an overflow of 80 % passing 149 p (100 mesh), the multiplier from Table 3 at 80 % passing is 1.25. The micron size for the application is 149 p (100 mesh). The D50c required = 1.25 x 149 = 186 p for the application. The separation that a cyclone/hydroclone can achieve can be approximated from the following relation. The Dc50 (base) for a given diameter cyclone is multiplied times a series of correction factors designated by C, C2, and C3 ... 

---