Tray Classifier

Tray Classifier A hybrid like the screw-conveyor classifier, the tray classifier rakes pulp up the sloping bottom of a tank while solvent flows in the opposite direction. The solvent is forced by a baffle to the bottom of the tank at the lower end before it overflows. The sohds must be rugged enough to stand the stress of raking. 

Three principal types of cross-flow tray are used, classified according to the method used to contact the vapour and liquid. 

Figure 1. Slurry reactors classified by the contacting pattern and mechanical devices (a) slurry (bubble) column (b) countercurrent column (c) co-current upflow (d) co-current downflow (e) stirred vessel (C) draft tube reactor (g) tray column (h) rotating disc or multi-agitated column reactor (i) three-phase spray column — liquid flow —> gas flow.

In addition, the pairs of trays were classified in six groups according to their sealing rank, I to VI (Figure 4B and C), and the sealing rank was handled as a covariate in the analysis-of-variance model. No interaction terms between the main factors or between the covariate and the main factors were defined in the model. 

Cross-flow trays are also classified according to the number of liquid passes on the plate. The design shown in Figure 11.23a is a single-pass plate. For low liquid flow... 

Devices for effecting contact of vapor and liquid may be classified as shown in Table 12.6. Recently, there has been a trend away from the conventional crossflow devices, in the direction of counterflow devices, mostly packings. Still, an enormous number of older columns are operating with trays, and thus the technology of tray design and analysis is important. 

For packed columns, which are classified as counterflow columns (most trays are crossflow devices), mass transfer is related to transfer tassa in connterflow vapor-liquid cou(acting Hie most-used criterion of efficiency is the height equivalent to a theoretical plate (HETP) thet was first introduced by Peters 1... 

Although most carousel apphcations in industry use human operators to store and retrieve the parts, fully automated systems have also been installed by replacing the human operator with automatic insert/extract devices to remove or insert the trays/tote boxes automatically. Also, depending on the plane of rotation, carousels are classified as horizontal carousels or vertical carousels. 

Conventional dryers used in the mineral-processing industry are classified as hearth type, shaft type, and grate type. Other types of dryers used less commonly in current practice are the spray type, fluid-bed type, pneumatic or flash type, conveyor type, drum type, stationary- and rotating-tray type, infrared type, and others. Only the more commonly used dryers are discussed in this chapter. 

Each technique has advantages and disadvantages. Packed columns are flexible as the packing can be easily modified for optimisation of each recovery process, but they are best suited to small scale operations. Tray columns are used for large scale, low to medium flow rate applications involving non-corrosive materials. Spray systems are used almost entirely for applications where pressure drop is critical such as flue gas treatment. Types of equipment classified as spray columns include cyclone and venturi systems. Bubble column equipment is a low cost, low maintenance option however back mixing can occur which reduces the counter-current flows required for optimum absorption. 

Going one level up in aggregation we consider the structures of complete columns. Conventionally, RD columns are classified in hybrid and non-hybrid units, depending on the distribution of reactive trays inside the column. Thus, hybrid columns are distillation columns with a reactive core and nonreactive sections (rectifying and/or stripping sections). Non-hybrid RD columns denote columns where all trays including condenser and reboiler are reactive (Giittinger, 1998). Hybrid columns are commonly... 

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