Distillation stripping equations

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. 

The HETP of a packed-tower section, valid for either distillation or dilute-gas absorption and stripping svstems in which constant molal overflow can be assumed and in which no chemical reactions occur, is related to the height of one overall gas-phase mass-transfer unit Hqc by the equation... 

The component balance equations for reflux drum, column enriching section, feed plate, column stripping section and the column base and reboiler are very similar to those derived previously for the binary distillation example CONSTILL, but are now expressed in multicomponent terms as described in Section 3.3.3.4. 

Reaction of Chlorine with Compounds. 1. Take a strip of filter paper, wet it with several drops of freshly distilled turpentine, and introduce it, using pincers, into a bottle with chlorine. What is observed Write the equation of the reaction. 

SC (simultaneous correction) method. The MESH equations are reduced to a set of N(2C +1) nonlinear equations in the mass flow rates of liquid components ltJ and vapor components and the temperatures 2J. The enthalpies and equilibrium constants Kg are determined by the primary variables lijt vtj, and Tf. The nonlinear equations are solved by the Newton-Raphson method. A convergence criterion is made up of deviations from material, equilibrium, and enthalpy balances simultaneously, and corrections for the next iterations are made automatically. The method is applicable to distillation, absorption and stripping in single and multiple columns. The calculation flowsketch is in Figure 13.19. A brief description of the method also will be given. The availability of computer programs in the open literature was cited earlier in this section. 

Approximate design equations applicable only to the case of pure physical desorption are developed later in this section for both packed and tray stripping towers. A more rigorous approach using distillation concepts may be found in Sec. 13. A brief discussion of desorption with cnemical reaction is given in the subsection Absorption with Chemical Reaction. ... 

Referring to Figure 2.2 for MVC column configuration, the model equations for the rectifying section are the same (except the reboiler equations) as those presented for conventional batch distillation column (Type III, IV, V in section 4.2). The model equations for the stripping section are the same (except the condenser equations) as those presented for inverted batch distillation column (Type III, IV, V in section 4.3.2). However, note that the vapour and liquid flow rates in the rectifying and stripping sections will not be same because of the introduction of the feed plate. 

Abundant descriptions of the theoretical basis and procedures for computer methods appear in recent literature and are summarized in books by King (1980, Chapter 10), Seader and Henley (1998, Chapter 15), and Kister (1992, Chapter 4). The present chapter will be devoted to the basic equations, the kinds of process specifications that can be made and met, and convergence criteria applicable to iterative calculations of problems of distillation, absorption, and stripping. To a certain extent, the same methods are applicable to liquid-liquid extraction and other phase separation processes. 

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. 

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