Liquid feeds

Practical experience has shown that the most convenient and best means of expressing R is in terms of the solute concentrations in the washed cake hquid the feed liquid (or unwashed cake liquid), and the cake wash hquid. Furthermore, the wash ratio N may also be expressed either as a volume or weight ratio. 

Process data Sp. gr. of feed liquid = 1.0 TDS (total dissolved solids) in feed liquid = 4.0 wt % fresh water used for washing vacuum level = 18 in Hg final cake liquid content = 25 wt %. 

For columns in which there is a substantial flash of the feed liquid, or in which the feed is a vapor of a different composition than the internal vapor, a collector plate can be installed above the feed point. The purpose of this plate is to provide mixing of the vapor phase in the gas risers so that a more uniform vapor composition enters the rectifying section of the column. 

In determining the proper size and number of cyclones required for a given application, two main objectives must be considered. The first is the classification or separation that is required, and the second is the volume of feed slurry to be handled. In the case of hydroclones, before determining whether these objectives can be achieved, it is necessary to establish a base condition as follows Feed liquid - water at 20 C. Feed solids - spherical particles of 2.65 specific gravity Feed concentration - less than 1 % solids by volume Pressure drop - 69 kPa (10 psi) Cyclone geometry - "standard cyclone" as described above. 

The carrier should not dissolve in the feed liquid or receptor phase in order to avoid leakage from the liquid membrane. In order to achieve sufficient selectivity, minimization of nonselective transport through the bulk of the membrane liquid is required. Liquid membranes can be divided into three basic types [6] emulsion supported and bulk liquid membranes, respectively (Fig. 5-2). 

X = mols of component i in vapor plus mols of component i in liquid divided by the total mols of feed (liquid + vapor)... 

For tray columns, bubble caps, valves or sieve, the feed liquid usually enters the column either in between functioning trays or at the top (reflux). The liquid or liq-uid/vapor mixture for flashing liquids must be dispersed uniformly across the tray. Such an arrangement often requires a special tray designed for the purpose to allow... 

Feintuch [221] pre.sents calculations for a pipe distributor with tray and downcomers to disperse the reflux or feed liquid uniformly across the tray (which should not be counted as a working tray, but a distribtuion device) and... 

Hydrotreating was carried out at 3.1 MPa (450 psig) and 613 K (340 °C) in a three-phase upflow fixed-bed reactor (Figure 1). The feed liquid was prepared by combining different quantities of 1.0 wt% tetralin (Aldrich, 99%), 0.02 wt% N as quinoline (Aldrich, 99%), 0.05 wt% S as 4,6-dimethyldibenzothiophene (4,6-DMDBT, Fisher, 95%), 0.3 wt% S as dimethyldisulfide (DMDS, Aldrich, 99%), n-octane (Aldrich, 99%), and balance n-tridecane (Alfa Aesar, 99%). Liquid product compositions were determined with a Hewlett-Packard 5890A chromatograph equipped with a 50 m dimethylsiloxane colunm (Chrompack, CPSil 5B) of 0.32 mm i.d. Reaction products were identified by matching retention times with commercially available standards. 

Methanol feed/concentra-tion Liquid feed/O.SM Liquid feed/1 M Vapor feed Vapor feed Liquid feed/1 M Liquid feed/1 M Liquid feed/1 M... 

Physical state of the feed liquid, slurry, wet solid. 

Bubble-point calculation, feed (liquid feed)... 

To solve Equation 9.50, start by assuming a feed condition such that q can be fixed. Saturated liquid feed (i.e. q = 1) is normally assumed in an initial design as it tends to decrease the minimum reflux ratio relative to a vaporized feed. Liquid feeds are also preferred because the pressure at which the column operates can easily be increased if required by pumping the liquid to a higher pressure. Increasing the pressure of a vapor feed is much more expensive as it requires a compressor rather than a pump. Feeding a subcooled liquid or a superheated vapor brings inefficiency to the separation as the feed material must first return to saturated conditions before it can participate in the distillation process. 

The height of the column for a packed column needs to allow for liquid distribution and redistribution. As the feed enters the column, the liquid above the feed needs to be collected, combined with the feed liquid and distributed across the packing below the feed using troughs,... 

In Figure 10.10a, it can be seen that for porous membranes, the partial pressure and concentration profiles vary continuously from the bulk feed to the bulk permeate. This is not the case with nonporous dense membranes, as illustrated in Figure 10.10b. Partial pressure or concentration of the feed liquid just adjacent to the upstream membrane interface is higher than the partial pressure or concentration at the upstream interface. Also, the partial pressure or concentration is higher just downstream of the membrane interface than in the permeate at the interface. The concentrations at the membrane interface and just adjacent to the membrane interface can be related according to an equilibrium partition coefficient KM i. This can be defined as (see Figure 10.10b) ... 

Henry s law coefficient 3 = PA/CA for hydrogen dissolved in feed liquid = 2240 bar/(kmol/m3). 

Quench pool/catch tank This type of system, as shown in Fig. 23-55, is used to condense, cool, react with, and/or collect a mixture of liquid and vapors discharging from a relief device by passing them through a pool of liquid in a vessel. Feed vapor and liquid (if present) are sparged into the pool of cool liquid, where the vapors are condensed and the liquid is cooled. If the feed materials are miscible with the pool liquid, they mix with and are diluted by the pool liquid if not, the condensate, feed liquid, and pool liquid separate into layers after the emergency relief event is over. The condensed vapors, feed liquid, and quench liquid are contained in the vessel until they are sent to final disposal. 

The distribution of fhe feed liquid and of binder fhroughout the bed and on the surface of individual parficles depends upon the structure of fhe bed parficles and fhe viscosify of fhe feed solution. A binder solution which increases rapidly in viscosity as solution is evaporated, and the concentration of binder increases, is less likely to be able to flow around a bed parficle and cover fhe surface area and consequently layered particle growth is much less probable. A solution for which the viscosity remains more or less constant with concentration is better able to spread around a particle before the solution dries and forms a solid crusf. However, fhe intensity of particle-particle contacts makes it extremely unlikely that significant coverage of the surface will occur. 

When the fluidized bed consists of non-porous particles, solvent in the feed liquid is evaporated in a well-defined zone close to the spray nozzle and from fhe surface of the bed particles with which it inevitably comes into contact. No permanent gas jet or void exists in this region particle motion is not well ordered and no regular coating of parficles wifh feed solution takes place. The random and intense contact between particles and liquid results in agglomeration. Even if the mass and heat balances for the bed as a whole have been satisfied, both... 

V particle volume Vb volume of binder per particle Vg granule envelope volume Wa mass flow rate of fluidizing gas XV mass flow rate of feed liquid Xs mass fraction of solute in feed liquid... 

A pressurized tank (10 bar) is used for the storage of distilled water fed to the reactor. To feed liquid water, a specific mass flow controller (Quantim, Brooks) is used. 

Pure component in gas phase and first-order kinetics in the gas reactant In this case, the gas phase is a pure component A (CAG is constant) and the concentration of A in the feed liquid phase is considered to be zero (unsaturated liquid phase). Furthermore, A is slightly soluble in the liquid (HA is large) so that KL = fg, while the intrinsic rate is of first order with respect to A —rm = kmCAS, per unit mass of catalyst. 

---