Simple Spray Towers

Simple Spray Towers The other extreme to the pipeline and reverse jet contactors is an open vessel where spray is injected down into upflowing gas to form a rain of liquid. The advantage of simple spray towers is that they give low gas pressure drop and also tend to be nonfouling. 

Unlike simple spray towers that operate at gas velocities on the order of 0.6 to 1.5 m/s (2 to 5 ft/s), cyclonic scrubbers are designed to operate at gas velocities of 60 to 180 m/s (200 to 600 ft/s). This makes cyclonic scrubbers much more efficient than spray towers in removing particulates due to the much greater particle-to-liquid relative velocity and turbulence. However, cyclonic type scrubbers are still not as efficient as ventmi scrubbers. 

Fig. 2. Types of spiay towers (a) horizontal spray chamber (b) simple vertical spray tower (c) cyclonic spray tower, Pease-Anthony type (d) cyclonic spray...

Spray Towers These are simple gravity extractors, consisting of empty towers with provisions for introducing and removing liquids at the ends (see Fig. 15-32). The interface can be run above the top distributor, below the bottom distributor, or in the middle, depending on where the best performance is achieved. Because of severe axial back mixing, it is difficult to achieve the equivalent of more than one or two theoretical stages or transfer units on one side of the interface. For this reason they have only rarely been applied in extraction applications. 

For the absorption of soluble gases or particulates from the gas streams, scrubbers can be used. These are generally simple packed columns, spray towers, or Venturi units. Design methods are well established [236]. Attention must be paid to the prevention of sprays, mists, and carryover when wet scrubbers are used. 

Natural-draft cooling towers evolved from spray ponds. The simplest and earliest design consisted of a small water spray pond surrounded with walls having inwardly sloping louvers. Figure 4.9 shows a cross section of a simple cooling tower formed by enclosing a spray pond with louvered walls. 

Figure 4.9 Cross section of a simple cooling tower formed by enclosing a spray pond with louvered walls.

Limestone Long-Term Tests with Two Scrubber Loops and Forced Oxidation. The venturi/spray tower system was modified for two-scrubber-loop operation with forced oxidation as shown in Figure 2. Two tanks were used in the oxidation loop (venturi loop) air was injected to the first of these tanks through a simple 3-inch diameter pipe below the agitator. Adipic acid was dry-fed to the spray tower effluent hold tank. This was accomplished by manually adding one-pound increments hourly to maintain specified concentration, usually totaling only a few pounds per hour. A small screw feeder would serve the purpose in a full-scale plant. 

The commoner and preferred alternative is to use air coolers of simple design. The heated ambient air up to temperatures of 250-400 C is mixed with the quench air of the NSD spray tower furnace. This direct application of heat is simple and cheap provided that the distance between the sulphonation operation and the NSD spray tower is no more than 1(X) m. A lagged pipeline connects the sulphonation plant and the spray tower furnace. 

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