Evaporator costs associated with

By use of selective membranes, water can be removed by filtration from the juice in order to effect its concentration. Depending upon the molecular size of the compounds and the cut-off value of the membrane used, there is likely to be some loss of flavour components. These may be recovered from the permeate by distillation and returned to the juice concentrate. Concentration by these methods is less effective in terms of folding than other methods but can provide advantages in specific cases for example, capital costs associated with hyperfiltration are around 10-30% less than for evaporative systems with aroma recovery equipment. 

Concentration. Clarified filtrates, centrates, or column eluates are usually too dilute for use in their specific applications, thus, substantial amounts of water must be removed. This can be achieved by evaporation or by ultrafiltration. Concentration methods used in industrial settings, such as evaporation, which is done under vacuum, and solvent extraction, may or may not be suitable for dewatering proteins because of their potential for thermal or chemical denaturation, and due to high energy costs associated with evaporation. The benefit of evaporation is that nonvolatile compounds that may stabilize the proteins are retained. 

Although there are clearly some specific advantages with the wiped film evaporators, they have not been widely applied for commercial polystyrene production. Reasons for this are most likely the high equipment and maintenance costs associated with these types of units. 

The two major costs associated with evaporators, as with any process equipment, are capital investment and operating costs. The best estimate of the installed cost of evaporation systems is, of course, a firm bid from a vendor. The installed cost, however, can be estimated based on the heat transfer surface area, as in Peters and Timmerhaus. Costs taken from published references must be adjusted for changes subsequent to the time of publication. To do this, one may use an index such as the Marshall and Swift allindustry index. The value of this index is published each month in Chemical Engineering, a McGraw-Hill publication. Further information on the use of this and other cost indices as well as their histories are available, for example, in Peters and Timmerhaus and Ulrich.f Variation of purchased evaporator costs with material of construction and pressure can also be found in Ulrich. ... 

The chlor-alkali industry s development of ion-exchange membrane-based electrolytic cells in the early 1970s was driven by environmental concerns associated with mercury and asbestos and the desire to reduce energy costs associated with electrolysis and caustic evaporation [1] (Ihble 4.8.1). 

Acryhc and methacryhc nonaqueous dispersions (NADs) are primarily utilized by the coatings industry to avoid certain difficulties associated with aqueous dispersion (emulsion) polymers. Water as a suspension medium has numerous practical advantages, but also some inherent difficulties a high heat of evaporation, a low boiling point, and an evaporation rate that depends on the prevailing humidity. Nonaqueous dispersions alleviate these problems, but introduce others such as flammabihty, increased cost, odor, and toxicity. 

Processability will be important insofar as the need for complex equipment will add to cost, and it may ultimately render the material useless for this type of application. An example is melting point. Even if all other factors were attractively addressed, a high melting point would require special melting equipment and may in fact be dan-gerons to the patient. There are, of course, alternative methods of delivery to melting, snch as solvent evaporation, but the risks associated with those methods must also be evaluated. 

Extractive distillation processes are still widely used for nitric acid concentration. Because the operational and maintenance problems associated with sulfuric acid concentration plants are considerable, and their capital cost substantial, attention has been directed periodically to the use of extractive agents other than sulfuric acid. Phosphoric acid (I) acts like sulfuric acid but poses similar problems of reconcentration. Solutions of certain metallic salts, in particular metallic nitrates, permit similar enhancement of relative volatility and are readily reconcentrated in straightforward evaporation equipment, offering the possibility of a compact integrated concentration process. 

The results obtained should also be used to calculate and confirm the cooling system volume, rate of evaporation, and cycles of concentration. Quite often the results show that the initial site-data information obtained, and subsequent proposals for water treatment volumes and costs, bear little resemblance to actual practice. If this is the case, the earlier that the buyer and engineering manager are aware of the situation, the better. However, it is incumbent on the field service engineer to devise a plan to minimize the cost and control effects associated with the new position. 

The high capital investment cost of the Asahi process is due to the necessity for large absorbers, evaporators, crystallizers, dryers, rotary kiln crackers and screw decanter separators. The major operating and maintenance costs are electricity, fuel oil, steam and chemicals such as soda ash, EDTA and limestone. The requirement for consumption of large amounts of utilities is associated with the operation principle and design of the Asahi process. According to the economic evaluation, equipment required for N0X and SO2 absorption (such as packed-bed absorbers) accounts for 20% of total direct capital investment for treatment of dithionate ion (such as evaporator, crystallizer, dryer, and cracker) it accounts for about 40% and for treatment of nitrogen-sulfur compounds (such as screw decanter and cracker) it accounts for only 2%. 

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