Strippers design

An appropriate procedure for executing the design of an absorber-stripper system is to set up a carefully selected series of design cases and then evaluate the investment costs, the operating costs, and the operability of each case. Some of the economic factors that need to be considered in selec ting the optimum absorber-stripper design are discussed later in the subsec tion Economic Design of Absorption Systems. ... 

In these equations, the first term is a correction for finite liqiiid-phase concentrations, and the integral term represents the numbers of transfer units required for dilute solutions. It would be very unusual in practice to find an example in which the first (logarithmic) term is of any significance in a stripper design. 

Typical Fractionator-Absorber/Stripper Design Number of Troys... 

In the past several years, more attentions have been given to improving mechanical performance of the reactor stripper. Proprietary stripper designs are being offered by the FCC technology licensers in attempts to improve the catalyst/steam contact. 

To decide the most economic water flow-rate, the stripper design should be considered together with the absorption design, but for the purpose of this example the absorption design will be considered alone. Using Figure 11.40 the number of stages required at different water rates will be determined and the optimum rate chosen ... 

Use 0.8, as the higher concentration will favour the stripper design and operation, without significantly increasing the number of stages needed in the absorber. 

The relationships between temperature, pressure, and composition for the Urea—C02 — NH3 — H20 system are given in References 5 and 6. These are equilibrium relationships. The reaction velocity may be obtained from the graph in Figure 5 of Reference 5, which is reproduced below for ease of reference (Figure FI). Some stripper design data appear in Reference 7. 

G. Bonani, P. Eberhardt, HJ. Hofmann, Th.R. Niklaus, M. Suter, H.A. Synal and W. Wolfli, Efficiency improvements with a new stripper design, Nucl. Instrum. Methods B 52, 338 344 (1990). 

For most sour water stripper design work, a computer is used to perform the calculations. Several of the proposed sour-water modules were incorporated into a tower program and a series of designs on a typical sour-water stripper have been undertaken. 

Spent-catalyst stripper. The stripper in the example shown in Figure 33 is an annular zone between the reactor shell and the periphery of the grid. Numerous other stripper designs have also been employed (53). These alternatives include a central stripping section, with an... 

Four key factors determine the efficiency with which volatile compounds may he removed from the liquid phase in an air stripper. Air-stripper design must include... 

A graphic comparison of the stripping factor (S) and the number of transfer units (NTU) shows that beyond S = 4-5, little additional contaminant removal occurs (9), as shown in Fig. 2. A stripping factor of 3 is suggested for most calculations of the required air-to-water ratio. NTU for air-stripper design can be calculated by substituting the desired removal efficiency into Eq. (8). The product of the HTU and the NTU yields the packed column height necessary to effect the desired removal of the contaminants ... 

FIGURE 6.2-4 Chart for absorber and stripper design by Gas Processors Suppliers Association procedure. (From GPS A Engineering Data Book Reproduced with permission of Gas Process ass Suppliers Asso-cialinn, Tulea. OK.)... 

In order to solve the problem by means of the DPE, the two critical parameters, namely and have to be specified. By merely specifying the flowrate of vapor and liquid streams it is simple to determine the reflux ratio. It is important to emphasize again that constant molar overflow (CMO) is assumed, meaning that the vapor and liquid flows remain constant throughout the column (see Section 3.3.2). This is a standard assumption in absorber and stripper design, and is generally a very good one, but it can be relaxed if the situation calls for it [5,6]. Recall that the reflux ratio is defined as... 

Notice that the nonsharp side-stripper design shown in Figure 6.31 is qualitatively similar to the one depicted here. Although the TT method is only applicable to the idealized case of sharp splits and constant relative volatilities, it is very useful for initial design estimates for the minimum energy demands of a structure and comparison. Once values have been determined for each CS, it is fairly simple to convey these values in terms of the previously defined split ratios. For the side stripper ... 

Overhead temperature on stripper > design reflux flowrate too low/[flooded] / [foaming] /feed contaminated with light hydrocarbons. 

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