Condensers partial condensation

The operating line for the rectifying section then intersects the diagonal at point (jcc.xtd). This is true for either a partial or a total condenser. (Partial condensers are discussed in the next section.)... 

Separation of mixtures of condensable and non-condensable components. If a fluid mixture contains both condensable and noncondensable components, then a partial condensation followed by a simple phase separator often can give a food separation. This is essentially a single-stage distillation operation. It is a special case that deserves attention in some detail later. 

When a mixture contains components with a broad range of volatilities, either a partial condensation from the vapor phase or a partial vaporization from the liquid phase followed by a simple phase split often can produce an effective separation. This is in essence a single-stage distillation process. However, by its very nature, a single-stage separation does not produce pure products hence further separation of both liquid and vapor streams is often required. 

The reactor effluent is thus likely to contain hydrogen, methane, benzene, toluene, and diphenyl. Because of the large differences in volatility of these components, it seems likely that partial condensation will allow the effluent to be split into a vapor stream containing predominantly hydrogen and methane and a liquid stream containing predominantly benzene, toluene, and diphenyl. 

Consider a three-product separation as in Fig. 5.11a in which the lightest and heaviest components are chosen to be the key separation in the first column. Two further columns are required to produce pure products (see Fig. 5.11a). However, note from Fig. 5.11a that the bottoms and overheads of the second and third columns are both pure B. Hence the second and third columns could simply be connected and product B taken as a sidestream (see Fig. 5.116). The arrangement in Fig. 5.116 is known as a prefractionator arrangement. Note that the first column in Fig. 5.116, the prefractionator, has a partial condenser to reduce the overall energy consumption. Comparing the prefractionator arrangement in Fig. 5.116 with the conventional... 

Consider now thermal coupling of the prefractionator arrangement from Fig. 5.116. Figure 5.16a shows a prefi-actionator arrangement with partial condenser and reboiler on the prefractionator. Figure 5.166 shows the equivalent thermally coupled prefractionator arrangement sometimes known as a Petlyuk column. To make the two arrangements in Fig. 5.16 equivalent, the thermally coupled prefractionator requires extra plates to substitute for the prefractionator condenser and reboiler. 

The output from the turbine might be superheated or partially condensed, as is the case in Fig. 6.32. If the exhaust steam is to be used for process heating, ideally it should be close to saturated conditions. If the exhaust steam is significantly superheated, it can be desuperheated by direct injection of boiler feedwater, which vaporizes and cools the steam. However, if saturated steam is fed to a steam main, with significant potential for heat losses from the main, then it is desirable to retain some superheat rather than desuperheat the steam to saturated conditions. If saturated steam is fed to the main, then heat losses will cause excessive condensation in the main, which is not desirable. On the other hand, if the exhaust steam from the turbine is partially condensed, the condensate is separated and the steam used for heating. 

The Claisen condensation is initiated by deprotonation of an ester molecule by sodium ethanolate to give a carbanion that is stabilized, mostly by resonance, as an enolate. This carbanion makes a nucleophilic attack at the partially positively charged carbon atom of the e.ster group, leading to the formation of a C-C bond and the elimination ofan ethanolate ion, This Claisen condensation only proceeds in strongly basic conditions with a pH of about 14. 

Liquids by liquids. The apparatus represented by Fig. 11, 58, 3 is employed for the extraction of aqueous solutions by solvents lighter than water, such as ether or benzene. The solvent distilled from the flask (attached to the lower end) and condensed by the reflux condenser (fltted to the upper end) passes through the funnel down a narrow tube, partially open at the lower end, into the aqueous solution, then rises to the surface and returns to the flask, having during its passage extracted some portion of the dissolved material from it. To improve the efficiency of the process. 

Place 50 g. (57 ml.) of dry A.R. benzene and 0 5 ml. of dry p rridine (1) (dried over potassium hydroxide pellets) in a 500 ml. round-bottomed flask. Attach a reflux condenser to the flask and an inverted funnel (just dipping into some water in a beaker) to the top of the condenser (Fig. II, 13, 8, b). Partially immerse the flask in a bath of cold water, supported upon a tripod and gauze. Carefully pour 125 g, (40 ml.) of bromine (for precautions to be taken with bromine, see Section 111,35, Note 1) through a condenser and immediately insert the absorption device into the upper end of the condenser. A vigorous reaction soon occurs and hydrogen bromide is evolved which is absorbed by the water in the beaker when the reaction slackens, warm the bath to 25-30° for... 

Hydrolysis of benzanilide. Place 5 g. of benzanilide and 50 ml. of 70 per cent, sulphuric acid in a small flask fitted with a reflux condenser, and boU gently for 30 minutes. Some of the benzoio acid will vapourise in the steam and solidify in the condenser. Pour 60 ml. of hot water down the condenser this will dislodge and partially dissolve the benzoic acid. Cool the flask in ice water filter off the benzoic acid (anifine sulphate does not separate at this dilution), wash well with water, drain, dry upon filter paper, and identify by m.p. (121°) and other tests. Render the filtrate alkaline by cautiously adding 10 per cent, sodium hydroxide solution, cool and isolate the aniline by ether extraction. Recover the ether and test the residue for anifine (Section IV,100). 

Bromo-4-aminotoluene hydrochloride. Transfer the partially dried 3-bromo-4-acetaminotoluene to a 1 5-litre round-bottomed flask, add 250 ml. of rectified spirit, and reflux on a water bath until the sohd dissolves completely. Introduce through the condenser 250 ml. of concentrated hydrochloric acid to the boihng solution and continue the refluxing for a further 3 hours. During this time crystals of 3-bromo-4-aminotoluene hydrochloride separate. Pour the hot mixture into a 1-Utre beaker and cool thoroughly. Filter the crystals of the hydrochloride at the pump through a Buchner funnel and wash rapidly with two 50 ml. portions of chilled rectified spirit. The yield of the hydrochloride is 150 g. 

A modified Hahn condenser, a form of partial condenser, is illustrated in Fig. VI, 12, 1 it is best constructed of Pyrex glass. The dimensions given are only approximate and may be varied slightly. The inside clearance should be approximately 0-3 cm. a water jacket should be fitted over the central portion of the side arm by moans of rubber stoppers. Alternatively, the side arm may have a length of about 10 cm. and a condenser fitted to this in the usual manner. An approximately 1 cm. layer of absolute alcohol is placed in the inner condensing tube and the top of the tube is connected to a reflux condenser. The outside of the condenser below the side arm should be insulated with asbestos cloth or paper. The refluxing mixture boils the ethyl alcohol in the inner tube, most of the isopropyl alcohol is returned to the flask and the acetone distils over. 

The important feature is that a three-dimensional gel network comes from the condensation of partially hydroly2ed species. Thus, the microstmcture of a gel is governed by the rate of particle (cluster) growth and their extent of crosslinking or, more specifically, by the relative rates of hydrolysis and condensation (3). 

The Stainicaibon process is described in Figures 3—7. The synthesis section of the plant consists of the reactor, stripper, high pressure carbamate condenser, and a high pressure reactor off-gas scmbber. In order to obtain a maximum urea yield pet pass through the reactor, a pressure of 14 MPa (140 bar) and a 2.95/1 NH —CO2 molar ratio is maintained. The reactor effluent is distributed over the stripper tubes (falling-film type shell and tube exchanger) and contacted by the CO2, countercurrendy. This causes the partial NH pressure to decrease and the carbamate to decompose. 

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