Liquid volume requirements

The large liquid volume required can be obtained by using a deep liquid level on the plates or by having the overflow from a plate pass thro igh a holding tank for the chemical reaction before it is added to the plate below. Deep liquid levels give undesirable action with normal-type bubble plates, but tall caps and risers can be used to obtain satisfactory operation. 

If we raise the temperature still further, the liquid vaporizes to form nitrogen gas, taking whatever density is necessary to fill the container. The density now depends upon the volume of the container and the temperature. For the sake of comparison, suppose the gaseous nitrogen is placed in that volume that gives a pressure of one atmosphere when the container is placed in an ice bath at 0°C. Then the density is found to be only 0.00125 gram per milliliter. This means that the volume required for one mole of gas is... 

Aluminum sulfate generally produces a large sludge volume and is slow to react and often difficult to de-water. It is usually supplied in dry blocks or a = 50% strength liquid. The required dose rate varies considerably, but it is approximately 20 to 100 ppm, as supplied. 

We can operate at the required liquid volume—say, by putting the reactor on load cells—but the gas-phase volume and thus the total volume may change upon scaleup. Correlations are needed for the gas-phase holdup and for kiAj. A typical correlation for kiAj is that by Middleton ... 

Liquid flows continuously into an initially empty tank, containing a full-depth heating coil. As the tank fills, an increasing proportion of the coil is covered by liquid. Once the tank is full, the liquid starts to overflow, but heating is maintained. A total mass balance is required to model the changing liquid volume and this is combined with a dynamic heat balance equation. 

Solid precursor is interesting for storage the tank volume required for a given autonomy will indeed be lower than the tank volume needed to store liquid urea. 

If the reaction occurs in the liquid phase at 25 °C, determine the reactor volume requirements for cascades of one and three identical CSTR s. The rate at which liquid feed is supplied is 0.278 m3/ksec. Use the graphical approach outlined previously. The following constraints are applicable. 

For the liquid-phase reaction A + B products at 20°C, suppose 40% conversion of A is desired in steady-state operation. The reaction is pseudo-first-oider with respect to A, with kA = 0.0257 hr1 at 20°C. The total volumetric flow rate is 1.8 m3 h 1, and the inlet molar flow rates of A and B are FAo and Fbo mol h 1, respectively. Determine the vessel volume required, if. for safety, it can only be filled to 75% capacity. 

An exothermic first-order liquid-phase reaction A - R is conducted in a PFR. Determine the volume required for 90% conversion of A, if the process is adiabatic. 

Determine Ihe type of reactor with the smallest volume for the second-order liquid-phase reaction A - products, where (—rA) = k c, and the desired fractional conversion is 0.60. Calculate the volume required. 

In situations 3 and 4, as much interface area as possible with a minimum volume of bulk liquid is required. However, hydrogenations are not very fast reactions and, in most cases, situations 1 or 2 prevail. 

The mass spectrometer is also incompatible with the HPLC system, but for a different reason. The ordinary mass spectrometer operates under very low pressure (a high vacuum see Chapter 10), and thus the liquid detection path must rapidly convert from a very high pressure and large liquid volume to a very low pressure and a gaseous state. Several approaches to this problem have been used, but probably the most popular is the thermospray (TS) technique. In this technique, the column effluent is converted to a fine mist (spray) as it passes through a small-diameter heated nozzle. The analyte molecules, which must be thermally stable, are preionized with the presence of a dissolved salt. A portion of the spray is introduced into the mass spectrometer. The analyte and mobile phase must be polar if the TS technique is used because the mobile phase must dissolve the required salt and the components must interact with the analyte molecule. See Workplace Scene 13.5. 

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