Charging trickle method

The effect of physical processes on reactor performance is more complex than for two-phase systems because both gas-liquid and liquid-solid interphase transport effects may be coupled with the intrinsic rate. The most common types of three-phase reactors are the slurry and trickle-bed reactors. These have found wide applications in the petroleum industry. A slurry reactor is a multi-phase flow reactor in which the reactant gas is bubbled through a solution containing solid catalyst particles. The reactor may operate continuously as a steady flow system with respect to both gas and liquid phases. Alternatively, a fixed charge of liquid is initially added to the stirred vessel, and the gas is continuously added such that the reactor is batch with respect to the liquid phase. This method is used in some hydrogenation reactions such as hydrogenation of oils in a slurry of nickel catalyst particles. Figure 4-15 shows a slurry-type reactor used for polymerization of ethylene in a sluiTy of solid catalyst particles in a solvent of cyclohexane. 

Trickle charging is used only for Pb cells. The current used in trickle charging is very much less than the rated battery current. The method is used for storage batteries which supply little or no current as a normal condition. They therefore remain charged for long periods and a small trickle of current is sufficient to maintain the charge. 

This is a charge conducted at a constant rate. The rate is usually at or below the finish rate. A trickle charge is a low-rate constant-current charge given to maintain the battery at a fuUy charged condition. This should be used only when the charging rate is matched to the battery. Some portable power and a few smaU-size stationary batteries use the trickle-charge method. 

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