Case Study

Steam Distillation Figure

Pharmacia & Upjohn Steam Stripper Case Study 1993 by Dr. Anthony Cooper, APV Americas In 1990, The Upjohn Company In Kalamazoo, Michigan, USA had a problem with the release of small quantities of methylene chloride into the atmosphere. The methylene chloride was actually in a waste water stream and was released during certain process operations on this water. Although the water contained other volatile organic chemicals, it was only necessary to design a process to remove the methylene...

Solvent Recovery

The term solvent recovery often has been a somewhat vague label applied to the many different ways in which solvents can be reclaimed by industry. One approach employed in the printing and coatings industries is merely to take impure solvents containing both soluble and insoluble particles and evaporate the solvent from the solids. For a duty of this type, APV offers the Paraflash evaporator, a compact unit which combines a Paraflow plate heat exchanger and a small separator. As the solvent...

Principal Of Operation

Alcohol Stripping Systems

For water miscible and water immiscible high volatile compounds, the process is a relatively straight forward distillation system. For many of the systems, vapor liquid equilibrium data are available in the literature and in the many process simulation software programs. Steam stripping can also be used to remove low volatile components when the components have low miscibility with water. Those compounds can all be effectively removed from water by steam stripping, even though they have a lower...

Modular Systems

Azeotropic Distillation Column

Many distillation systems are suitable for modular construction. The main advantage to modular construction is that most of the assembly of equipment and piping is carried out in the factory. This is far more efficient and generally much more economical than field construction. Also, this results in much shorter installation times on site. For columns of 3 ft 900mm diameter or smaller, it is usually possible to mount the column and all auxiliary equipment onto a single module. This can be...

Basic Principles Of Distillation

When a mixture of two or more liquids is heated and boiled, the vapor has a different composition than the liquid. For example, if a10 mixture of ethanol in water is boiled, the vapor will contain over 50 ethanol. The vapor can be condensed and boiled again, which will result in an even higher concentration of ethanol. Distillation operates on this principle. Clearly, repeated boiling and condensing is a clumsy process, however, this can be done as a continuous process in a distillation column....

Azeotropic Distillation Without an Entraining Agent

Distillation Alcohol

Certain binary systems form vapor azeotropes that, when condensed, form a two phase liquid without the presence of a third component. The separation is achieved with the combination of an organic column and an aqueous column coupled with a decanter. This is shown schematically in Figure 24. The vapors from each column are condensed, and the resulting two phase liquids are combined and decanted in a single vessel. The organic phase is returned as reflux to the organic column and the aqueous...

Azeotropic Distillation With an Entraining Agent

Ethanol Distillation Flow Sheet

The most common form of azeotropic distillation is adding a third component to the azeotropic mixture in a distillation column. This third component essentially changes the vapor liquid relationship between the two components and allows separation. Using ethanol water as the example, the column is usually operated with a continuous feed of the azeotrope into the column, which contains the third component. This causes a ternary azeotrope to form in the vapor at the top of the column. When this...

Steam Stripping

The term steam stripping can be applied to any system where rising steam vapors in a column strip out the volatile components in the liquid. In particular, the term is applied to systems where steam is used to strip out partially miscible organic chemicals, even though the organic chemicals have boiling points above water. For example, toluene, which has a boiling point of 110 C, can be stripped out of water with steam. The low solubility of toluene in water changes the activity coefficient,...

Reboiler

Although there are many types of reboilers, the shell and tube thermosyphon reboiler is used most frequently. Boiling within the vertical tubes of the exchanger produces liquid circulation and eliminates the need for a pump. A typical arrangement is shown in Figure 9. For certain duties, particularly when the bottoms liquid has a tendency to foul heat transfer surfaces, it is desirable to pump the liquid through a forced circulation reboiler. Since boiling can be suppressed by use of an orifice...

Sieve Tray

The sieve tray is a low cost device which consists of a perforated plate that usually has holes of 3 16 inch to 1 inch 5 to 25mm diameter, a downcomer, and an outlet weir. Although inexpensive, a correctly designed sieve tray can be comparable to other styles in vapor and liquid capacities, pressure drop and efficiency. For flexibility, however, it is inferior to valve and bubble cap trays. It is also sometimes unacceptable for low liquid loads when weeping has to be minimized. Depending on...

Preheaterscoolers

Preheater Distillation Column

The degree to which fluids are aggressive to metals and gasketing materials generally determines the selection of plate or shell and tube preheaters and product coolers. If fluids are not overly aggressive toward gasket materials, a plate heat exchanger is an extremely efficient preheater since a very close temperature approach may be achieved. Added economy is realized by using heat from the top and bottoms product for all necessary preheating. While plate type units can be supplied with...

Valve Tray

Valve Trays

While the valve tray dates back to the rivet type first used In 1922, many design Improvements and innumerable valve types have been introduced in recent years. Two types of valves are illustrated in Figure 7. These valves provide the following 1. Throughputs and efficiencies can be as high as sieve or bubble cap trays. 2. Very high flexibility can be achieved and turndown ratios of 4 to 1 can be obtained without having to resort to large pressure drops at the high end of the operating range....

Batch Distillation

When particularly complex or small operations require recovery of the more volatile component, APV can offer batch distillation systems of various capacities. Essentially a rectification type process, batch distillation involves pumping a batch of liquid feed into a tank where boiling occurs. Vapor rising through a column above the tank combines with reflux coming down the column to effect concentration. This approach is not too effective for purifying the less volatile component since there is...

Tray Devices

Downcomer Distillation

While there are perhaps five basic distillation trays suitable for industrial use, there are many design variations of differing degrees of importance and a confusing array of trade names applied to their products by tray manufacturers. The most modern and commonly used devices include sieve, valve, bubble cap, dual flow, and baffle trays - each with its advantages and preferred usage. Of these, the sieve and valve type trays currently are most often specified. For a better understanding of...

Dual Flow Tray

The dual flow tray is a high hole area sieve tray without a downcomer. The liquid passes down the same holes through which the vapor rises. Since no downcomer is used, the cost of the tray is lower than that of a conventional sieve tray. In addition, the less complex design allows for easier cleaning. In recent years, use of the dual flow tray has declined somewhat because of difficulties experienced with partial liquid vapor bypassing of the two phases, particularly in larger diameter columns....

Ponchon Savarit

Ponchon Savarit

Where Pa and Pb are the vapor pressures of components a and b at a given temperature. The partial pressure p of component a above a binary ideal solution can be calculated by Where xa is the mole fraction of component a in the liquid. Similarly in a binary mixture, for component b. pb Pb-xb Notice that the sum of the partial pressures must equal the total system pressure P pb pa. For non ideal mixtures usually the case with steam stripping duties , the partial pressure is calculated from Where...