Liquid operations

Unlike the case with liquid operations, where numerous restrictions are applied for safe handling (particularly for nonconductive liquids), powder operations are normally considered only with respect to the provision of proper grounding unless MlEs less than about 10 mJ are involved or flammable vapor is additionally present. For powders in air... 

Ionic liquids operate in true biphasic mode. While the recovery and recyclability of ionic liquid was found to be more efficient than with the conventional AICI3 catalyst (red oil), the selectivity for the monoalkylated aromatic hydrocarbon was lower. In this gas-liquid-liquid reaction, the solubility of the reactants in the ionic phase (e.g. the benzene/ethene ratio in the ionic phase) and the mixing of the phases were probably critical. This is an example in which the engineering aspects are of the utmost importance. 

Item No. No. of Units Service Liquid Oper. Temp. F So. Gr.GPM Avail. NPSH, FI. Ditchorge Pretf. PSI6 Speed RPM BHP Pump H.P. Driver Driver Type File Ref. 

Figure 9-54. Typical pressure drop—capacity curves for countercurrent gas-liquid operation, for Koch Flexipac . Used by permission of Koch Engineering Co., Inc., Bull. KFP-4. Parameter lines on charts are gpm/ft. ...

Fito, P. and Chiralt, A. 1997. Osmotic dehydration An approach of the modelling of solid food-liquid operations. In Food Engineering 2000 (P. Fito, E. Ortega-Rodriguez, and G.V. Barbosa-C novas, eds), pp. 231-252. Chapman Hall, New York. 

A height of at least 10 ft (3 m) above the vessels internal liquid operating levels (liquid hold-up in distillation column trays is not included)... 

FM Data Sheet 7-32. Flammable Liquid Operations. Factory Mutual Engineering Corporation, Norwood, MA. 

A successful extraction of hepfane from fhe azeotropic mixture with ethanol by means of a liquid-liquid operation with the IL, [QQIm][PFJ, was recently published [153]. 

High-pressure conditions favour a smaller bubble size and narrower bubble-size distribution, and therefore lead to higher gas hold-up in BSCR, except in systems operated with porous plate distributors and at low gas velocities. For design purposes in BSCR at high pressure, where the liquids operate in the batch mode, Luo et al. [31] proposed the following formula for the calculation of the gas hold-up, based on their proper experimental data and those of many other authors [1,26,31-34] for various systems of gas, liquid and solids ... 

The separation processes involving all-liquid operations can be implemented continuously, which, is very advantageous industrially, as it ensures high throughputs. 

As stated earlier, distillation and related vapor-liquid operations are by far the most common separation processes In the organic-chemical, petroleum and allied Industries It Is unlikely that adsorption will ever rival distillation In frequency of use, but adsorption s share of the separation task should grow substantially The purpose of this section Is to indicate the likely areas of growth in existing and new applications, as well as the technological Innovations which would foster this growth ... 

Special cantilevers have been designed for in-vacuum as well as in-liquid operation. Piezoresistive cantilevers [205] and micromachined cantilevers with an integrated electronic sensor [206] make the deflection measurements more simple, however demonstrate lower force sensitivity. 

Sie ST, Lebens PJM. Monolithic reactors for countercurrent gas-liquid operation. In Cybulski A, Moulijn JA, eds. Structured Catalysts and Reactors. New York Marcel Dekker, 1998 305-321. 

Const, (power) dissipation energy per unit vessel volume Const, impeller discharge flow energy Turbulent dispersion Gas-liquid operation Reaction requiring microscale mixing... 

Monolithic catalyst carriers are state-of-the-art in exhaust gas cleaning, for example in automobiles, DeNOx or removal of VOCs. To minimize diffusion length and to increase the geometric surface area, monoliths with small-diameter channels have been developed which can be produced easily by extrusion, followed by calcination. In the past few years the application of monoliths in gas-liquid operation has been investigated intensively [10-13]. 

In monolithic catalyst carriers with wider channels, the hquid forms a film on the channel walls, whereas in the core of the channel a continuous gas phase exists. As shown by Lebens [10], countercurrent gas-liquid operation is now possible, and shows certain advantages over the countercurrent trickle bed operation. Typical channel diameters are 3-5 mm, and the geometric surface areas are between 550 and 1000 m2 m 3. Below the flooding point, almost no hydrodynamic interaction between the gas and hquid can be observed for example, the RTD is the same for both co-current and countercurrent operation. Apart from some surface waves, the film flow is completely laminar. 

Due to an always high water contents at the reactor inlet, the eventual internal water loop (as described in Fig. 8.3) should not be a problem. However, if co-current and countercurrent operation is compared (Fig. 8.28), a clear difference between these two operation modes is found only for the water concentrations, whereas the gain in space-time yield is limited to around 10 %. This can be attributed to the high recirculation rate of the liquid, whereas in both experiments the gas phase was vented after one pass. Therefore, the gas-liquid operation was of the cross-flow-type rather than pure co-current or countercurrent To identify the effect of pure co-current or countercurrent operation, the gas phase should also be recycled. 

Mesh Microcontactor A mesh microcontactor contains a microstructured plate with regular circular openings through which separate gas and liquid streams come into contact [270,271]. Stability of the interface and prevention of breakthrough are achieved by adjusting the pressure. Gas-liquid operation requires a low gas flow... 

These ideas of impeller flow, head and power input as related to operating variables have some merit for a qualitative description of the effects of the operating variables on the process. However, it requires extensive experience, and usually actual experiments, to decide whether a system performance is favored by a particular combination of flow and head. (Rushton and Oldshue (R12) note that high values of Q/3Care preferred for blending and solid suspension, low ratios for liquid-liquid and gas-liquid operations.) This approach still requires the systematic study of impeller speed and diameter as process variables. 

There are oidy a small number of cracking operations in Africa. The main producers are Egypt, Libya and Nigeria each with a capacity of about 300,000 t/y and South Africa with a capacity of 585,000 t/y. The latter production is integrated with the large coal and gas to liquids operations of Sasol. 

An analysis is made of the factors which pose a limit to representative downscaling of catalyst testing in continuous fixed-bed reactors operated with either gas or gas-liquid flow. Main limiting factors are the axial dispersion and, in the case of gas-liquid operation, also the contacting of the catalyst. The effects of catalyst and reactor geometries are quantified, and boundaries for safe operation are indicated. 

The flammable liquid operations and all its appurtenances must be physically separated from the rest of the plant for maximum safety. Care should be taken that the separate buildings are no larger than production efficiency demands in... 

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