Liquid stream compositions

Liquid stream compositions that do not reflect the lighter components in the sample. A sample of gasoline is collected in a bottle. The methane and half the ethane are flashed off as the bottle warms on the laboratory bench. 

In an equilibrium separation, a feed stream containing m components at given composition, pressure, and enthalpy (or temperature if in a single phase) is split into two streams in equilibrium, here taken to be a vapor and a liquid. The flow rates of the feed, vapor, and liquid streams are, respectively,... 

A hypothetical moving-bed system and a Hquid-phase composition profile are shown in Figure 7. The adsorbent circulates continuously as a dense bed in a closed cycle and moves up the adsorbent chamber from bottom to top. Liquid streams flow down through the bed countercurrently to the soHd. The feed is assumed to be a binary mixture of A and B, with component A being adsorbed selectively. Feed is introduced to the bed as shown. 

This equation gives the relation between the bulk compositions of the gas and liquid streams at each level in the tower for conditions in which the operating curve can be approximated by a straight hne. 

The tower operates in the same manner as a condensate stabilizer with reflux. The inlet liquid stream is heated by exchange with the gas to approximately 30 F and is injected in the tower at about the point in the tower where the temperature is 30 F. By adjusting the pressure, number of trays, and the amount of reboiler duty, the composition of the bottoms liquid can be determined. 

Both liquid and vapor products are withdrawn, with liquid reflux composition being equal to liquid product composition. Note that on an equilibrium diagram the partitd condenser liquid and vapor stream s respective compositions are in equilibrium, but only when combined do they represent the intersection of the operating line with the 45° slope (Figure 8-14). 

However, if he selects an outlet stream composition (say the liquid stream) instead of a flow-rate, then the simultaneous solution of the mass balance and v-l-e relationships would not be necessary. The stream compositions could be calculated by the following step-by-step (sequential) procedure ... 

A separator divides a process stream into three phases a liquid organic stream, a liquid aqueous stream, and a gas stream. The feed stream contains three components, all of which are present to some extent in the separated steams. The composition and flowrate of the feed stream are known. All the streams will be at the same temperature and pressure. The phase equilibria for the three phases is available. How many design variables need to be specified in order to calculate the output stream compositions and flow rates ... 

In order to calculate the outlet stream composition it is reasonable, for a condenser, to assume that the gas and liquid streams are in equilibrium at the outlet liquid temperature... 

This example illustrates the use of liquid-liquid phase equilibria in material balance calculations. The condensate stream from the condenser described in Example 4.2 is fed to a decanter to separate the condensed water and dichloroethane (EDC). Calculate the decanter outlet stream compositions. 

The precise location of the feed point will affect the number of stages required for a specified separation and the subsequent operation of the column. As a general rule, the feed should enter the column at the point that gives the best match between the feed composition (vapour and liquid if two phases) and the vapour and liquid streams in the column. In practice, it is wise to provide two or three feed-point nozzles located round the predicted feed point to allow for uncertainties in the design calculations and data, and possible changes in the feed composition after start-up. 

Equation 12.22 relates the compositions of vapor and liquid streams passing each other in the stripping section of a column. Equation 12.22 can be used together with vapor-liquid equilibrium calculations to calculate a composition profile in the stripping section of the column, similar to that of the rectifying section of the column as described above. The calculation is started with an assumed bottoms composition and Equation 12.22 applied repeatedly with vapor-liquid equilibrium calculations working up the column. 

From the point of view of the composite curves, the location of the pinch and the A Tmin at the pinch would depend on which kind of streams were located in the region of the point of closest approach between the composite curves. If only liquid streams were present around the point of closest approach of the composite curves, then in the above example, ATmin = 10°C will apply. If there were only gas streams in the region around the point of closest approach, then in the above example, ATmin = 20°C would apply. If there was a mixture of liquid and gas streams at the point of closest approach, then A Tmin = 15°C would apply. 

The pinch design method, as discussed so far, has assumed the same A Tmin applied between all stream matches. In Chapter 16, it was discussed how the basic targeting methods for the composite curves and the problem table algorithm can be modified to allow stream-specific values of A Tmin. The example was quoted in which liquid streams were required to have a A Tmin contribution of 5°C and gas streams a ATmin contribution of 10°C. For liquid-liquid matches, this would lead to a ATmin = 10°C. For gas-gas matches, this would lead to a ATmin = 20°C. For liquid-gas matches, it will lead to a ATmin = 15°C 2. Modifying the problem table and the composite curves to account for these stream-specific values of ATmin is straightforward. But how is the pinch design method modified to take account of such A Tmin contributions Figure 18.9 illustrates the approach. Suppose the interval pinch temperature from the problem table is 120°C. This would correspond with hot stream pinch temperatures of 125°C and 130°C for hot streams with ATmin contributions of 5°C and 10°C respectively. For... 

By an analysis of the composition of gas or liquid stream and the arrangement or conditions at the particular facility one can prudently arrive at the optimum detection philosophy. 

Liquid-solid separations, pilot plant, 18 731 Liquid-solid suspension, effective thermal conductivity of, 13 277 Liquid-state metal-matrix composite processing, 16 166-169 Liquid steel, 23 250 Liquid stream dehydration, molecular sieves in, 16 840... 

Various correlations for mean droplet size generated by plain-jet, prefilming, and miscellaneous air-blast atomizers using air as atomization gas are listed in Tables 4.7, 4.8, 4.9, and 4.10, respectively. In these correlations, ALR is the mass flow rate ratio of air to liquid, ALR = mAlmL, Dp is the prefilmer diameter, Dh is the hydraulic mean diameter of air exit duct, vr is the kinematic viscosity ratio relative to water, a is the radial distance from cup lip, DL is the diameter of cup at lip, Up is the cup peripheral velocity, Ur is the air to liquid velocity ratio defined as U=UAIUp, Lw is the diameter of wetted periphery between air and liquid streams, Aa is the flow area of atomizing air stream, m is a power index, PA is the pressure of air, and B is a composite numerical factor. The important parameters influencing the mean droplet size include relative velocity between atomization air/gas and liquid, mass flow rate ratio of air to liquid, physical properties of liquid (viscosity, density, surface tension) and air (density), and atomizer geometry as described by nozzle diameter, prefilmer diameter, etc. 

Control of the vaporization process, i.e. the temperature of the capillary, is of crucial importance. Optimum performance is obtained with around 95% vaporization of the liquid stream. Too much heat results in vaporization occurring within the capillary with deposition of analyte and, if operation of the interface under these conditions is continued for any length of time, blockage of the capillary. On the other hand, if insufficient heat is applied to the capillary, vaporization does not occur and liquid flows from it and no spray is obtained. The optimum temperature is dependent on a number of parameters, among the most important being the composition of the mobile phase and its flow rate. Good temperature control is therefore required to obtain the best conditions when gradient elution is employed. 

Equation 11.84 represents any operating line relating the composition of the vapour yn rising from a plate to the composition of the liquid reflux entering the plate, or alternatively it represents the relation between the composition of the vapour and liquid streams between any two plates. From equation 11.83, it may be seen that all such operating lines pass through a common pole N of coordinates xd and Hd. 

Alternatively, noting that the right-hand side of equations 11.77, 11.78 and 11.79 are independent of conditions below the feed plate, a stream N may be defined with mass equal to the difference between the vapour and liquid streams between two plates, of composition xd and of enthalpy Hd. The three quantities Vn, Ln+1, and N are then on a straight line passing through N, as shown in Figure 11.27. 

Step 5 Calculate the density of the reservoir liquid at reservoir conditions using the feed stream composition from Step 1, reservoir temperature, and bubble-point pressure. The procedure is described in Chapter 11. 

Very often the liquids to be processed may be contaminated with substances detrimental to some types of zeolites consequently a complete knowledge of the process stream composition and physical properties must be available before preliminary sieve selection can be made. In the absence of prior knowledge of separation factors, competitive co-adsorption, environmental stability, regeneration techniques, or irreversible zeolite contamination, zeoli te contamination, zeolite specification must be proceded by time-con-... 

Table 1 gives the components present in the crude DDSO and their properties critical pressure (Pc), critical temperature (Tc), critical volume (Vc) and acentric factor (co). These properties were obtained from hypothetical components (a tool of the commercial simulator HYSYS) that are created through the UNIFAC group contribution. The developed DISMOL simulator requires these properties (mean free path enthalpy of vaporization mass diffusivity vapor pressure liquid density heat capacity thermal conductivity viscosity and equipment, process, and system characteristics that are simulation inputs) in calculating other properties of the system, such as evaporation rate, temperature and concentration profiles, residence time, stream compositions, and flow rates (output from the simulation). Furthermore, film thickness and liquid velocity profile on the evaporator are also calculated. 

A coaxial CF-FAB interface was applied to the coupling of CE with tandem MS. A pair of coaxial fused silica capillary columns were used to deliver, independently, the microcolumn effluent and the FAB matrix directly to the FAB probe tip face. The advantages of the system are that the composition and flow rates of the two liquid streams can be independently optimized, the FAB matrix does not affect the microcolumn separation process, and peak broadening is minimized because the two streams do not mix until they reach the tip of the FAB probe, where ion desorption occurs. 

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