Stripping calculations

The total of theoretical trays in the column is the sum of those obtained from the rectifying calculations, plus those of the stripping calculations, plus one for the feed tray. This does not include the reboiler or partial condenser as trays in the column. 

The stripping calculations are handled in a manner similar to the steps above, and using the figures indicated. 

One long side of the compartment wall was split into a large number of thin, horizontal strips and the heat flux from the gas layer to the center of each strip calculated using the well known expression... 

Smith studied the effect of boiling point differences of various cuts of hexane on miscella (218). Smith also determined the vapor pressure of hexane-soybean oil solutions at high solvent concentrations (211). When making stripping calculations, one should be aware that the last portions of solvent to vaporize consist of higher boiling constituents in that particular cut of solvent. 

Thus, the mole fraction of water vapor in a gas that is saturated, that is, in equilibrium contact with pure water (jc = 1.0), is given simply by the ratio of the vapor pressure of water at the system temperature divided by the system pressure. These equations find application in distillation, absorption, and stripping calculations. 

The Murphree efficiency is defined using vapor concentrations as a matter of custom, but the measured efficiencies are rarely based on analysis of the vapor phase because of the difficulty in getting reliable samples. Instead, samples are taken of the liquid on the plates, and the vapor compositions are determined from a McCabe-Thiele diagram. A plate efficiency can be defined using liquid concentrations, but this is used only occasionally for desorption or stripping calculations. 

The thickness of a pure silver plate on a base metal is to be determined by controlled-potential coulometry. The metal sheet is masked except for a circular area 0.50 cm in diameter electrical connection is made to the metal, the sheet is clamped in a cell so that the unmasked area is covered with electrolyte, and the silver plate is anodically stripped. Calculate the average thickness of the silver... 

This is because on one hand, heav wave is weaker and on the other hand, photoelastic testing method is unfavorable for observing the sound field of axial symmetry. The sound field (see Fig.4) excited by strip ciystal in solid is observed with photoelastic testing method. The wavefront of head wave can be see in Fig.4, which is a circumstantial evidence of wavefront of head wave excited just by point-shape crystal. We can calculate... 

Table 1 describes the timing results (in seconds) for a system of 4000 atoms on 4, 8 and 16 nodes. The average CPU seconds for 10 time steps per processor is calculated. In the case of the force-stripped row and force-row interleaving algorithms the CPU time is reduced by half each time the number of processors is doubled. This indicates a perfect speedup and efficiency as described in Table 2. Tables 3, refibm table3 and 5 describe the timing results, speedups and efficiencies for larger systems. In particular. Table 4 shows the scaling in the CPU time with increase in the system size. These results are very close to predicted theoretical results.

The concentration of copper in a sample of sea water is determined by anodic stripping voltammetry using the method of standard additions. When a 50.0-mL sample is analyzed, the peak current is 0.886 )J,A. A 5.00-)J,L spike of 10.0-ppm Cu + is added, giving a peak current of 2.52 )J,A. Calculate the parts per million of copper in the sample of sea water. 

In addition, most devices provide operator control of settings for temperature and/or response slope, isopotential point, zero or standardization, and function (pH, mV, or monovalent—bivalent cation—anion). Microprocessors are incorporated in advanced-design meters to faciHtate caHbration, calculation of measurement parameters, and automatic temperature compensation. Furthermore, pH meters are provided with output connectors for continuous readout via a strip-chart recorder and often with binary-coded decimal output for computer interconnections or connection to a printer. Although the accuracy of the measurement is not increased by the use of a recorder, the readabiHty of the displayed pH (on analogue models) can be expanded, and recording provides a permanent record and also information on response and equiHbrium times during measurement (5). 

Empirical attempts have been made to relate strip and grab test results, particularly for cotton fabrics, so that if one strength is known, the other can be calculated. The relationship is complex, depending on fiber strength and modulus, yam size and crimp, yam-to-yam friction, fabric cover factor, weave, weight, and other factors (19). 

The energy requirements for desorbing 1,1-dichloroethane from activated carbon in a stripping—adsorption process for water purification have been calculated at 112 kj/kg (14). Chlorinated hydrocarbons such as 1,1-dichloroethane may easily be removed from water by air or steam stripping. 

In a large number of processes, there ate unit operations related to vapot-Hquid separations distillation, absorption, extraction, stripping, flashing, and separation of Hquid and vapor stream arising from changes in temperatures and pressures. Calculations for these unit operations necessitate trial and... 

Some plants use a bleed-and-feed process where a calculated quantity is withdrawn to waste treat each day and replaced with an equivalent amount of fresh solution. Using cleaners that reject oils can be effective if proper equipment is available. Stripping racks and reject parts off-line helps extend the... 

It is assumed that process conditions and physical properties are known and the following are known or specified tube outside diameter D, tube geometrical arrangement (unit cell), shell inside diameter D shell outer tube limit baffle cut 4, baffle spacing and number of sealing strips N,. The effective tube length between tube sheets L may be either specified or calculated after the heat-transfer coefficient has been determined. If additional specific information (e.g., tube-baffle clearance) is available, the exact values (instead of estimates) of certain parameters may be used in the calculation with some improvement in accuracy. To complete the rating, it is necessary to know also the tube material and wall thickness or inside diameter. 

Example 2 Calculation of Kremser Method For the simple absorber specified in Fig. 13-44, a rigorous calculation procedure as described below gives results in Table 13-9. Values of were computed from component-product flow rates, and corresponding effective absorption and stripping factors were obtained by iterative calculations in using Eqs. (13-40) and (13-41) with N = 6. Use the Kremser method to estimate component-product rates if N is doubled to a value of 12. 

A knowledge of the reflux ratio (obtained from the specified distillate and top vapor rates) permits the calculation of (f d) from which ( i/d) is obtained, etc. Equation (13-50) is applied to each stage in succession until the ratio 2/d in the overflow from the stage above the feed stage is obtained. The calculations are then switched to the stripping section. 

In the inner-loop calculation sequence, component flow rates are computed from the MESH equations by the tridiagonal matrix method. The resulting bottoms-product flow rate deviates somewhat from the specified value of 50 lb mol/h. However, by modifying the component stripping factors with a base stripping factor, S, in (13-109) of 1,1863, the error in the bottoms flow rate is reduced to 0,73 percent. 

The design of a plate tower for gas-absorption or gas-stripping operations involves many of the same principles employed in distillation calculations, such as the determination of the number of theoretical plates needed to achieve a specified composition change (see Sec. 13). Distillation differs from gas absorption in that it involves the separation of components based on the distribution of the various substances between a gas phase and a hquid phase when all the components are present in Doth phases. In distillation, the new phase is generated From the original feed mixture by vaporization or condensation of the volatile components, and the separation is achieved by introducing reflux to the top of the tower. 

In gas absorption, the new phase consists of an inert nonvolatile solvent (absorption) or an inert nonsoluble gas (stripping), and normally no reflux is involved. The following paragraphs discuss some of the considerations peculiar to gas-absorption calculations for plate towers and some of the approximate design methods that can be employed when simplifying assumptions are vahd. 

Edmister, W. C., Absorption and Stripping-factor Functions for Distillation Calculation by Manual- and Digital-computer Methods, A.I.Ch.E. Journal, June 1957. 

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