Quench tank

This is covered by Huckins14, DIERS /Grossel171, Keiter191 and Singh151, who also discusses the need to account for level swell in a quench tank. 

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HoUow-fiber fabrication methods can be divided into two classes (61). The most common is solution spinning, in which a 20—30% polymer solution is extmded and precipitated into a bath of a nonsolvent, generally water. Solution spinning allows fibers with the asymmetric Loeb-Soufirajan stmcture to be made. An alternative technique is melt spinning, in which a hot polymer melt is extmded from an appropriate die and is then cooled and sohdified in air or a quench tank. Melt-spun fibers are usually relatively dense and have lower fluxes than solution-spun fibers, but because the fiber can be stretched after it leaves the die, very fine fibers can be made. Melt spinning can also be used with polymers such as poly(trimethylpentene), which are not soluble in convenient solvents and are difficult to form by wet spinning. 

FIG. 17-17 Quench tank for overflow or cyclone solids discharge. [Gilfillan et al., "The FluoSolids Reactor as a Source of Sulphur Dioxide, J. Chem. Metall. Min. See. S. Afr. (May 1954).]... 

Types of Equipment The three most commonly used types of equipment for handling emergency relief device effluents are blowdown drums (also called knockout drums or catch tanks), cyclone vapor-liquid separators, and quench tanks (also called passive scruh-hers). These are described as follows. 

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. 

The criteria for application and performance characteristics of blowdown drums, cyclone separators, and quench tanks are discussed as follows. 

FIG, 26-21 Quench tank with direct-contact baffle tray section. 

General In comparison with design information on blowdown drums and cyclone separators, there is very httle information in the open technical hterature on the design of quench tanks in the Chernies industry. What is available deSs with the design of quench tanks (Sso called suppression pools) for condensation of steam or steam-water mixtures from nuclear reactor safety vSves. Information and criteria from quench tanks in the nuclear industry can be used for the design of quench tanks in the chemicS industry. There have been sev-... 

Design Critena Pertinent criteria for quench tank sizing and design are presented below ... 

In controlled venting operation, the quench tank pressure is maintained at a desired level by a pressure controller/control valve system or pressure rehef valve. This mode of operation is used when the discharge mixture bubble point is close to or below the maximum ambient temperature, and it is desired to hmit the maximum quench tank pressure. 

QUENCH TANK VOLUME The total volume of the quench tank should be equal to the sum of the following volumes ... 

QUENCH TANK GEOMETRY Quench tanks can have any of the following three types of geometiy ... 

Figure 26-20 shows conventional quench tank sparger arrangements. As can be seen in this figure, the sparger can be of the follow-ing types ... 

Mass-Transfer Contact Section Where there is a strong possi-bihty that not all of the incoming vapors will be condensed in the pool, a direct-contact mass-transfer section is superimposed on the quench tank. This can be a baffle-tray section (as shown in Fig. 26-21) or a packed column sec tiou. 

For additional details on the design of blowdown drums, cyclone separators, and quench tanks, such as mechanical design, thrust forces, ancillary equipment, and safety considerations, refer to the books and articles listed in the General References. 

Operating pressure There are three modes of operation of a quench tank atmospheric pressure operation, nonvented operation, and controlled venting operation. Atmospheric operation is usually feasible when the effluent Being emitted has a bubble point well above the maximum ambient temperature. A very small quantity of vapor escapes with the air that is displaced as the tank fills with the emergency discharge (typically about 0.2 percent of the reactor contents). Depending on the toxic or flammable properties of the vapor, the vent from the quench tank can be routed to the atmosphere or must be sent to a scrubber or flare. 

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