Trays design temperatures

Many columns have water removal trays designed into the column. Top or bottom temperatures may have to be changed to expel the water if the column isn t provided with water removal trays. In some instances, the water can be expelled by venting the column through the safety relief system. 

An application of this instrument is illustrated in the study of color change in dehydrated carrots with storage at different temperatures. Typical results are given in Table IY. The measurements were made on the dry material packed level in a tray designed to fit at a specific level in the instrument. The instrument is mounted so that the tray rests horizontally and no cover glass is then necessary to hold the sample in place. 

The specification is the same for all plates at or below the weak-acid feed point. The only operating parameter in this region to change significantly is the temperature. The bottom plate temperature is 65°C and the weak-acid feed tray is closer to 50°C. Even this temperature difference is not expected to affect the tray design such that individual sieve plates need to be sized. The operating parameters at the bottom sieve tray are therefore given as follows ... 

Development in Palm Oil Deodorization. The main operation in the deodorizer is the stripping of volatile materials and thermal action due to the combined effects of superheated steam, high temperature, and efficient vacuum. The older deodorizers (prior to 1985) use bubble caps or sieve-tray designs to effect the... 

This definition has the advantage of being very simple to use however, it does not take into account the variation in efficiency from one stage to another due to changes in physical properties of the system caused by changes in composition and temperature. In addition, efficiencies for various species and for various tray designs may differ. 

Tray temperature often varies from one set of operating conditions to another (e.g., it is higher when a distillation column is pressured than when it is depressured). Often, the tray temperature is not the same as the shell temperature. Tray design should allow for thermal expansion of tray sections. Failure to do so may result in tray buckling or beam warping. 

To ensure practically no leakage, a leakage test is commonly conducted upon installation. In this test, the weep holes are plugged and the trays are filled with water to the top of the weir. The rate of fall of water level is then measvu ed. It has been recommended that this rate should not exceed 1 in per 20 minutes (48, 86, 257, 371, 409). If the leakage is not critical, a more liberal tolerance can be adopted (48). This test is not always conclusive, because a tray that leaks badly under test conditions may perform satisfactorily at the design temperature and vice versa. 

The solution to the RD problems results in the optimum number of trays, the optimal feed tray location, reflux ratio, condenser and reboiler duties and liquid hold-ups on each tray. Since the model contains both continuous e.g. temperature and composition) and discrete i.e. number of trays) design variables, it should be solved by MINLP optimization technique. 

Dehydration capacity vs. temperature (gas drying), 449-455 glycol circulation vs. tray capacity, 450-451 tray design, 451-452 reboiler temperature variable, 453 overheating glycol, 453—454... 

Figure 8.16 shows the column specifications in the HYSYS simulation file as received from the process design engineer. Note that the designer has included 12 potential specifications for the column, of which only two can be active at any given time. Here, the component fraction C3 in the bottoms and the tray 20 temperature are currently active. 

The base case design point is not the most profitable operation point. Under both control strategies, more profit can be made if the tray 20 temperature is reduced from its base case value of 63.8°C. A lower tray 20 temperature produces more bottoms stream volume, but at a higher TVP. But because the profitability of the increased volume is higher than the cost of the increased TVP of the bottoms stream, a lower tray 20 temperature set point is preferred. At some point, however, it is likely that a constraint will be hit on how much bottoms stream can be generated. For this work, it will be assumed that the maximum bottoms stream production that can be handled in blending is 200 m h ... 

Deodorization can be carried out ki batch, continuous, or semicontkiuous systems. Figure 4 shows a typical design for a semicontkiuous deodorizer. The heated ok is passed through a series of trays under vacuum. Steam is passed through the ok through a steam sparge ki the bottom of the tray. Volatiles are carried through the headspace and condensed. In addition to fatty acids and compounds responsible for odor, some tocopherols and sterols are also distilled kito the condensate. The amount of tocopherols distilled depends on deodorization temperature and vacuum. 

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