Dehydrating systems

A knock out vessel may on the other hand be followed by a variety of dehydrating systems depending upon the space available and the characteristics of the mixture. On land a continuous dehydration tank such as a wash tank may be employed. In this type of vessel crude oil enters the tank via an inlet spreader and water droplets fall out of the oil as it rises to the top of the tank. Such devices can reduce the water content to less than 2%. 

Although most of the installed solvent dehydration systems have been for ethanol dehydration, dehydration of other solvents including 2-propanol, ethylene glycol, acetone, and methylene chloride, has been considered. 

The hquid product streams are fed to a distillation system to remove the light impurities and to recover the ethanol as a 95% volume ethanol—water a2eotrope. To produce anhydrous ethanol, the ethanol—water a2eotrope is fed to a dehydration system. 

This chapter discusses the design of liquid glycol and solid bed dehydration systems that are the most common methods of dehydration used... 

Solid bed dehydration systems work on the principle of adsorption. Adsorption involves a form of adhesion between the surface of the solid desiccant and the water vapor in the gas. The water forms an extremely thin film that is held to the desiccant surface by forces of attraction, but there is no chemical reaction. The desiccant is a solid, granulated drying or dehydrating medium with an extremely large effective surface area per unit weight because of a multitude of microscopic pores and capillary... 

Figure 8-21 is a flow diagram for a typical two-tower solid desiccant dehydraiion unit. The essential components of any solid desiccant dehydration system are ... 

A similar classification scheme is used to gauge the severity of active CD.2 Patients with mild to moderate CD are typically ambulatory and have no evidence of dehydration, systemic toxicity, loss of body weight, or abdominal tenderness, mass, or obstruction. Moderate to severe disease is considered in patients who fail to respond to treatment for mild to moderate disease, or those with fever, weight loss, abdominal pain or tenderness, vomiting, intestinal obstruction, or significant anemia. Severe to fulminant CD is classified as the presence of persistent symptoms or evidence of systemic toxicity despite outpatient corticosteroid treatment, or presence of cachexia, rebound tenderness, intestinal obstruction, or abscess. 

In order to determine the optimum platform operating temperature it wos necessary to size the Glycol Dehydration System for the various platform operating temperotures considered. 

Selection of an optimized, energy-efficient crude oil dehydration system must consider the key variables of time, heat, coalescence, chemicals and gravity. The cost ol each of these must be weighed against the benefit if provides in solving a particular dehydration problem before an economical process can be structured. 

The optimum economic crude dehydration system will include a combination of these processes. Certainly some time will he required and it is a probability that some chemic al" aids can be jusiiiied, if not actually required. In most cases some form ol forced coalescence can Ik a gieal economic help. Ii is a reasonably rare occurrence when the addition ol some heal" is not required... 

Chemical additives are demulsifiers generally injected in the oil upstream of the dehydration system. The use of demulsifiers with a gravity separation device such as a three phase separator or settling tank can successfully remove as much as 95 percent of the produced water present in the oil. Removal of the remainder of the water droplets through... 

Figure 9.11 Photograph of a 50-m2 GFT plate-and-frame module and an ethanol dehydration system fitted with this type of module. The module is contained in the large vacuum chamber on the left-hand side of the pervaporation system [44]...

A similar study carried out on Malvasia delle Lipari grapes (Corte et al. 2001) showed that in the relevant passiti wine the content of glycosylated terpenes was extremely high, particularly in a sample obtained from grapes dried in an artificial dehydration system the wine obtained from the use of this artificial dehydration showed a glycosylated terpene... 

FIGURE 25 Medium-scale (30,000 liters/day) ethanol dehydration system by vapor permeation (Lurgi GmbH). 

Figure 20.8 shows a schematic flow diagram for a typical triethylene glycol dehydration system. The lean glycol is pumped to the top of an absorber column and flows downward in countercurrent contact with the water-wet gas entering the bottom of the... 

Wong T., Ko S., and Olgaard D. L. (1997) Generation and maintenance of pore pressure excess in a dehydrating system 2. Theoretical analysis. J. Geophys. Res. 102, 841-852. 

S. J. Wang, C. J. Lee, S. S. Jang, S. S. Shien,2008, Plant-wide design and control of acetic acide dehydration system via heterogeneous azeotropic distillation and divided wall distillation, J. Process Control, vol. 18, p. 45... 

Vapor pressures of DMSO and wafer are shown in Fig. ll-12d. Based on appearances, they could be separated by a single-stage batch distiUation (under vacuum and in a short time to avoid decomposition). Because of the affinity between these two liquids, however, a single-stage water stripper removed too much DMSO in the overhead stream. The solution to this problem was to insert a reflux condenser in the vessel with warm water in the jacket to aUow return of the entrained DMSO in the vapor stream back to the boilup. In accord with Fig. 11 -12d, the dehydration system pressure was maintained at about 50 mm Hg and the condenser jacket temperature was set at about 50-60°C, which successfully removed the water and maintained the freezing point near 18°C in the crystallizer. 

Ohtake, S., Schebor, C., Palecek, S.P., and de Pablo, J.J. Effect of sugar-phosphate mixtures on the stability of dppc membranes in dehydrated systems. Cryobiology, 48, 81, 2004. 

Comparing dehydration processes by activated alumina, molecular sieves, and methanol injection system, a methanol injection system is cheaper to build and operate than an activated alumina dehydration system when low water content natural gas is the feed. When natural gas with higher water... 

A few other dehydration systems are also widely used which employ glycol injection and contact with the gas. Mono-, or di-, or triethylene glycol solution is used for this purpose. The principles are very similar to the methanol dehydration system. The disadvantages associated with the glycol methods are inadequate distribution in the gas-gas exchangers, difficulty to remove from the dehydrated gas, foaming, and mutual solubility between the hydrocarbon liquids and the glycol solution. 

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