Evaporators applications

McKenaa, T. Design model of a wiped film evaporator, applications to the devolatilisation of polymer melts. Chemical Engineering Science 50(3), 453-467 (1995)... 

There are several ways to increase the steam economy, or to get more evaporation with less steam input, for certain types of evaporation applications. The use of multiple-effect configurations or compression evaporation can be considered for large flow rates of relatively dilute aqueous solutions. Both multiple-effect and compression evaporation systems require a sizable incremental capital investment over single-effect evaporators, and these systems are larger and more complex than the simpler one-stage evaporators. Like the multiple-effect evaporators described above, compression evaporation systems can only be justified by a reduced level of steam consumption. 

H2. Herbain, M., and Bertin, D., Micros parateur k usage multiple (filtration, essorage, Evaporation). Application aux dosages radiometriques. Bull, soc. chim. biol. 41, 637-642 (1959). 

Microfin tubes are widely used for in-tube convective condensation, as well as the evaporation applications noted in the previous subsection. 

While mathematical models have been developed for predicting performance of thin-film evaporators, suppliers of thin-film machinery maintain extensive pilot plant testing laboratories for obtaining development and process data with small evaporators. Data obtained from one or two days of testing on several drums of feed material are sufficient for predicting and scaling performance to large evaporator applications. 

Generally, though, steam jet ejectors and liquid-ring pumps are used for evaporator applications. 

The flow of solids suspended in a liquid stream is encountered in some evaporator applications. The characteristics of the flow depend upon the physical properties and relative amounts of the solid and liquid and upon the shape and particle size distribution of the solid being transported. 

In most evaporator applications the control of product quality is constantly affected by variations in feed rate and composition to the evaporator. In order to counter these load variations, the manipulated variable must attain a new operating level. In pure feedback or cascade arrangements, this new level is achieved by trial-and-error as performed by the feedback controller. 

Evaporation applications that, in the past, used single-effect designs because of low capacity or the need for expensive construction materials will increasingly use vapor compression as a means of... 

Used For Like 800, but quicker evaporation Application Technique Wipe on or spray on iqiplication Teaq> Ambient Tenq>erature Type of Molds No aluminum... 

Petroleum solvents are relatively light petroleum cuts, in the C4 to C14 range, and have numerous applications in industry and agriculture. Their use is often related to their tendency to evaporate consequently, they are classified as a function of their boiling points. 

Volatility is one of the most important properties of a hydrocarbon solvent. Volatility has a direct relation to the time it takes to evaporate the solvent and, therefore, to the drying time for the dissolved product. The desired value of volatility varies greatly with the nature of the dissolved product and its application temperature. Therefore, whether it be an ink that needs to dry at ambient temperature, sometimes very fast, or whether it be an extraction solvent, the volatility needs are not the same. 

The Marangoni effect has been observed on the rapid compression of a monolayer [54] and on application of an electric held, as in Ref. [55] it occurs on evaporation [56]. 

To prepare crystalline monoperphthalic acid, place the thoroughly dry ethereal solution (4) in a distilling flask equipped with a capillary tube connected with a calcium chloride or cotton wool drying tube, and attach the flask to a water pump. Evaporate the ether without the application of heat (ice will form on the flask) to a thin syrup (about 150 ml.). Transfer the syrup to an evaporating dish, rinse the flask with a little anhydrous ether, and add the rinsings to the syrup. Evaporate the remainder of the ether in a vacuum desiccator over concentrated sulphuric acid about 30 g. of monoperphthalic acid, m.p. 110° (decomp.), is obtained. 

The successful application of an external standardization or the method of standard additions, depends on the analyst s ability to handle samples and standards repro-ducibly. When a procedure cannot be controlled to the extent that all samples and standards are treated equally, the accuracy and precision of the standardization may suffer. For example, if an analyte is present in a volatile solvent, its concentration will increase if some solvent is lost to evaporation. Suppose that you have a sample and a standard with identical concentrations of analyte and identical signals. If both experience the same loss of solvent their concentrations of analyte and signals will continue to be identical. In effect, we can ignore changes in concentration due to evaporation provided that the samples and standards experience an equivalent loss of solvent. If an identical standard and sample experience different losses of solvent. 

The previous discussion demonstrates that measurement of precise isotope ratios requires a substantial amount of operator experience, particularly with samples that have not been examined previously. A choice of filament metal must be made, the preparation of the sample on the filament surface is important (particularly when activators are used), and the rate of evaporation (and therefore temperature control) may be crucial. Despite these challenges, this method of surface ionization is a useful technique for measuring precise isotope ratios for multiple isotopes. Other chapters in this book discuss practical details and applications. 

Ester interchange reactions are valuable, since, say, methyl esters of di-carboxylic acids are often more soluble and easier to purify than the diacid itself. The methanol by-product is easily removed by evaporation. Poly (ethylene terephthalate) is an example of a polymer prepared by double application of reaction 4 in Table 5.3. The first stage of the reaction is conducted at temperatures below 200°C and involves the interchange of dimethyl terephthalate with ethylene glycol... 

Emulsion polymerization also has the advantages of good heat transfer and low viscosity, which follow from the presence of the aqueous phase. The resulting aqueous dispersion of polymer is called a latex. The polymer can be subsequently separated from the aqueous portion of the latex or the latter can be used directly in eventual appUcations. For example, in coatings applications-such as paints, paper coatings, floor pohshes-soft polymer particles coalesce into a continuous film with the evaporation of water after the latex has been applied to the substrate. 

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

Paraffin wax vapor barriers are used in water rinse removers that can disperse the wax without coating the substrate. In soak tank applications, water is sometimes doated on top of an ad-solvent, neutral pH, nonwater rinse remover to prevent evaporation. Flotation devices that cover the exposed surface area may be used with other formulas. 

High test molasses (invert molasses) is produced from cane sugar when sucrose manufacture is restricted because of overproduction. The cane sugar at ca 55 wt % solids is en2ymatically converted to invert symp to prevent crystallisation and evaporated to a symp. The product is used in the same applications as blackstrap molasses. 

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