Liquid and Gas Load

The trickle bed reactors that operate in the downflow configuration and have a number of operational problems, including poor distribution of liquid and pulsing operation at high liquid and gas loading. Scaleup of these liquid-gas-solid reactors is much more difficult than a gas-solid or gas-liquid reactor. Nevertheless, the downflow system is convenient when the bed is filled with small catalyst particles. And, because the catalyst particles are small, these reactors are quite effective as filters of the incoming feed. Any suspended fine solids, such as fine clays from production operations, accumulate at the front end of the bed. Eventually, this will lead to high pressure differentials between the inlet and outlet end of the reactor. 

The number of trays is determined by dividing the theoretical number of stages, which is obtained from the relationships in Section III, by the appropriate tray efficiency. It is best to use experimental efficiency data for the system when available, but caution is required when extending such data to column design, because tray efficiency depends on tray geometry, liquid and gas loads, and physical properties, and these may vary from one contactor to another. In the absence of data, absorption efficiency can be estimated using O Connell s empirical correlation. This correlation should not be used outside its intended range of application. 

Determine the liquid and gas loadings. The liquid and gas loadings are defined by the liquid-to-gas ratio determined in step 3 and by the stipulation that the tower is to operate at an approach to flooding of 80 percent at constant L/G. For flooding defined at constant L/G, Eq. (11.1) becomes... 

Figure 5.6 Liquid and gas loads in typical trickle-bed reactors for gas oil hydroprocessing.

In terms of the hydraulic design of columns, the liquid and gas loads are major design parameters to be considered. For the liquid flow, the load characteristic is expressed as the liquid volume flow related on the inner column area ... 

Percent void space high amounts of open flow area tend to reduce pressure drop, minimize the possibilities of plugging due to solids accumulation, and increase loading and flooding liquid and gas flow rates. 

The only disadvantage of this method is that the obtained product (BA) has a lower bulk density. Such a puffed product, with large quantities of liquids and gas, can be loaded onto the expanded borax. For example, organic such as trichloroethylene, cyclohexanone and pentachlorophenol can be loaded at very high percentages onto the puffed borax, as can non-ionic and anionic surfactants, with the product retaining its free-flowing characteristics. This renders the puffed borax very useful in such diverse compositions as dairy cleaners, fabric softeners and bath additives [8]. 

Being a disperse system, the foam exhibits a more complex behaviour when subjected to mechanical loading, compared to that of its constituting phases liquid and gas. Of all rheological parameters the latter are characterised by the viscosity alone. The complete description of the foam system requires knowledge of the constants of elasticity (modulus of... 

Surface mass changes can result from sorptive interactions (i.e., adsorption or absorption) or chemical reactions between analyte and coating, and can be used for sensing applications in bodi liquid and gas phases. Although the absolute mass sensitivity of the uncoated sensor depends on the nature of the piezoelectric substrate, device dimensions, frequoicy of operation, and the acoustic mode that is utilized, a linear dependence is predicted in all cases. This allows a very general description of the working relationship between mass-loading and frequency shift, A/ , for AW devices to be written ... 

Saturators consisting of an evaporator and a recondenser have been used successfully for such applications. In the evaporator the gas bubbles through the liquid and is loaded with the compound above the desired concentration value. Therefore the temperature in the evaporator is kept at a value of S-10°C above the saturation temperature, corresponding to the desired concentration. Maintaining this temperature at approximately this level will suffice. 

Therefore, a range of on-line sensors will be installed to measure for instance temperatures (including those along the absorber and stripper), pressures, liquid and gas flows, gas composition and absorber and stripper solvent levels. Solvent sample points will be included for solvent extraction to facilitate detailed off-line composition analysis. The rich stream shall be equipped with a coriflow mass flow meter that is able to measure solvent density. Since the solvent density increases with CO2 loading, this means that one obtains an indication of die loading real-time. 

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