Tray-type reactors

FIG. 12-85 Perforated-tray type of reactor-discharge control. 

Figure 8.2.2 Conceptual scheme for a tray-type adiabatic reactor.

Because the catalyst is sensitive to sulfur, the gases are purified by one of several sulfur-removing processes, then are fed through heat exchangers into one of two types of reactors. With bed-in-place reactors, steam at around 4.5 kPa, in quantity sufficient to drive the gas compressors, can be generated. A tray-type reactor with gases introduced just above every bed... 

The second reactor to be described is the tray type, Figure 8, which allows the catalyst to be put on individual trays at certain depths throughout the reactor. In the usual design of this reactor cold synthesis gases are added between trays to drive the reacting gases to a lower temperature favoring a better equilibrium. 

Continuous reactors are at work all the time. This means newly introduced reactants mix to some extent with products. This extent is termed backmixing. A tower has many plates or baffles in it and experiences less backmixing as, for instance, a tank with no plates. Continuous reactors can then be found within towers and columns. Towers may be packed or plate (bubble cap or sieve tray) type. Optimum reactor design attempts to curtail the amount of dead space or areas where no reaction is taking place. It is also possible to have reactants take a shorter path than is necessary for optimum reaction. This is called shortcircuiting. 

Tray-type reactors. Intemally, a variety of different tray types may be used. The descriptive terms for these trays include bubble cap trays, flexitrays, ballast tra5 , float tray, sieve trays, turbogrid, and kittel trays. They use a variety of techniques, including sieve slots and holes, as well as caps or fitted mini skirts, to alter the residence time of the fluid that passes over them, thereby enabling a more complete reaction. 

Relationships Between Objects, Processes, and Events. Relationships can be causal, eg, if there is water in the reactor feed, then an explosion can take place. Relationships can also be stmctural, eg, a distiUation tower is a vessel containing trays that have sieves in them or relationships can be taxonomic, eg, a boiler is a type of heat exchanger. Knowledge in the form of relationships connects facts and descriptions that are already represented in some way in a system. Relational knowledge is also subject to uncertainty, especiaUy in the case of causal relationships. The representation scheme has to be able to express this uncertainty in some way. 

Figure 17.11. Types of contactors for reacting gases with liquids many of these also are suitable for reacting immiscible liquids. Tanks (a) with a gas entraining impeller (b) with baffled impellers (c) with a draft tube (d) with gas input through a rotating hollow shaft, (e) Venturi mixer for rapid reactions, (f) Self-priming turbine pump as a mixer-reactor, (g) Multispray chamber. Towers (h) parallel flow falling film (i) spray tower with gas as continuous phase (j) parallel flow packed tower (k) counter flow tray tower. (1) A doublepipe heat exchanger used as a tubular reactor.

FIG. 19-26 Types of industrial gas-liquid reactors, (a) Tray tower, (b) Packed, countercurrent, (c) Packed, co-current, (d) Falling liquid film, (e) Spray tower. (/) Bubble tower, (g) Venturi mixer. (h) Static in-line mixer, (t) Tubular flow. / Stirred tank. /, Centrifugal pump. (l) Two-phase flow in horizontal tubes. 

FIG. 19-31 Some examples of bubble column reactor types, (a) Conventional bubble column with no internals. (6) Tray bubble column, (c) Packed bubble column with the packing being either an inert or a catalyst. [From Mills, Ramachandran, and Chaudhari, Multiphase Reaction Engineeringfor Fine Chemicals and Pharmaceuticals, Reviews in Chemical Engineering, 8(1-2), 1992, Figs. 2, 3, and 4.]... 

Trays, fractionating assembly of sieve trays, 428 bubblecap, 428,430-433 capacity, F-factor, 429 capacity, Jersey Critical, 432 capacity, Souders-Brown, 432 cartridge, 428 design data sheet, 429 dualflow, 426 efficiency, 439-456 Linde, 430 ripple, 426 sieve, 428,429 turbogrid, 426 types, 426 valve. 429.430.432 Trickle reactors, 576, 607 Tridiagonal matrix, 407 Trommels, 335... 

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