Partial condensers temperature profile

An alternative method, which can also be used to estimate the pressure drop in a partial condenser, is given by Gloyer (1970). The pressure drop is calculated using an average vapour flow-rate in the shell (or tubes) estimated as a function of the ratio of the vapour flow-rate in and out of the shell (or tubes), and the temperature profile. 

Column 1 As the base case design in Table 5.3 shows, column 1 has 51 stages, and operates with a partial condenser with a duty of 1.371 MW at the top, and a side condenser with a duty of 8.144 MW at stage 2. It has no reboiler however, it receives a side heat stream with a duty of 15.299 MW to the last stage from section 2 of the plant. The temperature profiles of both columns are shown in Figure 5.9. 

Fig. 4.8 Influence of the inert gas on the partial pressure and temperature profiles. g vapour temperature, i s saturation temperature, pi partial pressure of the condensing vapour, po partial pressure of the inert gas, p = pi + po total pressure...

This method also considers the stage temperatures as the independent variables. The algorithm is applied to a single-feed, two-product column with a partial condenser and reboiler. As in the original Thiele-Geddes method, the problem definition is such that the feed component flow rates, are known and fixed. The column pressure profile is also fixed, as well as its configuration, which defines the number of stages and feed location. In addition, one product rate (the distillate) and one internal flow (such as the reflux rate, Lj) are specified. The solution method, outlined below, is described in detail by Holland (1975). 

For all examples, the column pressure is 400 lb/in2 abs, a partial condenser is used, and the feed enters as a liquid at its bubble-point temperature. The initial temperature profiles are taken to be linear between the pinches. Assumed values for Tr and Ts were Tr= Tfccd — 15°F and Ts = Tfeed -1- 15°F, and initial values for TD and TB were TD= Tfeed - 40°F and Tfeed + 40°F. Initially, take V = Vr = V2 for the rectifying section and Vj= Vs= Vr for the stripping section. Use the equilibrium and enthalpy data given in Tables B-2 and B-24 of App. B. 

For all examples column pressure = 400 lb/in2 abs, partial condenser, thermal condition of the feed is boiling-point liquid. Initial temperature profile linear between the pinches (252-282°F) for all examples. For Examples 11-7 and 11-8 the initial temperature profile was taken to be linear between 227 and 242°F for plates 1 through 5 and the temperature of the distillate was taken to be 217°F. Initial vapor rates V — V2 for all j. In Example 11-7 the liquid sidestream is withdrawn from plate 6 (the accumulator is assigned the number 1), and in Example 11-8, it is withdrawn five plates above the feed plate. Use the equilibrium and enthalpy data given in Tables B-2 and B-24 of the Appendix. 

Predicted column profiles for temperature, total vapor and liquid flow rates, and component vapor and liquid mole fractions are shown in Figure 6.24, where stages are numbered from the top down (stage 1 is the partial condenser, stage 14 is the partial reboiler). Computed heat exchanger duties are as follows ... 

Condensation processes are especially suitable for the cleaning of low flow highly concentrated streams of exhaust gas. The entire waste gas stream is cooled below the dew point of the vapors contained therein, so that these can condense on the surface of the heat exchanger (partial condensation). Theoretically, the achievable recovery rates depend only on the initial concentration, the purification temperature and the vapor pressure of the condensables at that temperature. In practice however, flow velocities, temperature profiles, the geometry of the equipment, etc. play decisive roles, as effects such as mist formation (aerosols), uneven flow in the condensers and uncontrolled ice formation interfere with the process of condensation and prevent an equilibrium concentration from being reached at the low temperatures. 

Profiles of partial pressure and temperature in a condenser when noncondensables are present partial pressure of... 

FIGURE 11.5 Upward thermal diffusion cloud chamber. Typical cloud chamber profiles of total gas-phase density, temperature, partial pressure p (n-nonane in this example), equilibrium vapor pressure p saturation ratio 5, and nucleation rate J, as a function of dimensionless chamber height at T = 308.4 K, S = 6.3, and total p = 108.5 kPa. (Reprinted with permission from Katz, J. L., Fisk, J. A. and Chakarov, V. M. Condensation of a Supersaturated vapor IX. Nucleation of ions, J. Chem. Phys. 101. Copyright 1994 American Institute of Physics.)... 

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