Process equipment columns

Figure 12 shows the plan and elevation views of a process unit piping (9). A dmm is supported off the piperack. Heat exchangers are located far enough back from the support columns so that they are accessible and their shell covers can be removed. Pumps are located underneath the piperack, but sufficient room is provided for maintenance equipment to access the motors and to remove the pump if necessary. The motor is always oriented away from the process equipment and located on that side of the piperack. Instmment valve drops are shown supported from the columns. The instmment trays themselves mn on the outside of the support columns. Flat turns are only made from the outside position of the piperack. Nozzle-to-nozzle pipe mns are made whenever possible. Larger lines are located on the outside of the piperack. Connections to nozzles above the rack are made from the top... 

Batch distillation equipment can range from a free-standing column with a reboiler, condenser, receiver, and vacuum system, to the use of a jacketed reactor with a condenser. Distillation often involves the generation of combustible vapors in the process equipment. This necessitates the containment of the vapor within the equipment, and the exclusion of air from the equipment, to prevent the formation of combustible mixtures that could lead to fire or explosion. 

NFPA requirements state that if equipment or process vessels, columns of tanks are suitably constructed of substantial steel construction adequately grounded, and do not give off flammable vapors, no other mechanism of lighting protection is required. This is also true of flares, vent stacks and metal chimneys by nature of their construction and grounding facilities. 

The process equipment consists mainly of two extraction columns with pulsating trays and four distillation columns according to Fig. 10.4 [7]. The feed, with a high content of aromatics, is pumped to the middle of the first extraction column where the aromatics are extracted with the solvent SI (tetraethylene glycol). In the lower part, the extracted aromatics are washed with S2 (dodecane). The outgoing raffinate phase R1 (containing aliphatics,... 

Deviation from the two ideal flow patterns can be caused by channeling of fluid, by recycling of fluid, or by creation of stagnant regions in the vessel. Figure 11.1 shows this behavior. In all types of process equipment, such as heat exchangers, packed columns, and reactors, this type of flow should be avoided since it always lowers the performance of the unit. 

Separation of components occurs as the analytes and mobile phase are pumped through the column. Eventually, each component elutes from the column as a narrow band or peak on the recorder. Detection of the eluting components is important, and this can be either selective or universal, depending upon the detector used. Tlte response of the detector to each component is displayed on a chart recorder or computer screen and is known as a chromatogram. To collect, store, and analyze chromatograms, computers, integrators, and other data processing equipment are frequently used. 

As with chemical weapons ingredients, the chemical equipment needed to make chemical warfare agents is commercially available just about anywhere. Certainly, to set up a full-scale poison gas production line, terrorists would need reactors and agitators, chemical storage tanks, containers, receivers, condensers for temperature control, distillation columns to separate chemical compounds, valves and pumps to move chemicals between reactors and other containers. Additionally, ideally the equipment would be corrosion-resistant. For a full-scale mustard gas production plant the price tag would be between 2.5 and 5 million. Approximately 10 million would be required to set up a plant to manufacture tabun, sarin or soman.47 Terrorists, however, can be assumed to forego the scale and the safety precautions that most governments would consider essential for a weapons programme. In fact, standard process equipment or a laboratory set-up of beakers and... 

The techniques that have been used to characterise the mechanical properties of microparticles may be classified as indirect and direct. The former includes measurement of breakage in a "shear" device, for example, a stirred vessel (Poncelet and Neufeld, 1989) or bubble column (Lu et ah, 1992). However, the results from these indirect techniques are rather difficult to use since the mechanical breakage depends not only on the mechanical properties but also the hydrodynamics of the processing equipment, and the latter are still not well understood. To overcome this problem, a cone and plate viscometer that can apply well-defined shear stresses has been used to study breakage of hybridomas (Born et ah, 1992), but this is not a widely applied or applicable technique because the forces are too small to break most cells. 

This paper gives a comprehensive review of the up-to-date modeling of reactive separation processes in columns equipped with structured packings and consider in detail two different modeling ways. The first approach is based on the application of CFD, whereas the second one employs the idea of hydrodynamic analogy between complex and simple flow patterns. 

In the introduction to this chapter it has been already pointed out that for the design of chemical process equipment rules of thumb exist. Upon closer examination, these rules provide conditions which unconsciously accept partial similarity. Actually, one cannot expect that complicated processes of fluid dynamics occurring during mass and heat transfer can be adequately described by criterions such as power per unit of volume, P/V, for mixing vessels and superficial gas velocity, v = q/S, for bubble columns. 

Operating and design specifications of the equipment used in the proposed process Extraction Column, EC... 

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