Karr extractor

Laboratory studies of the rearrangement process began with semi-continuous operation in a single, 200-mL, glass reactor, feeding 1 as a liquid and simultaneous distillation of 2,5-DHF, crotonaldehyde and unreacted 1. Catalyst recovery was performed as needed in a separatory funnel with n-octane as the extraction solvent. Further laboratory development was performed with one or more 1000-mL continuous reactors in series and catalyst recovery used a laboratory-scale, reciprocating-plate, counter-current, continuous extractor (Karr extractor). Final scale-up was to a semiworks plant (capacity ca. 4500 kg/day) using three, stainless steel, continuous stirred tank reactors (CSTR). 

Component CSTR-3 Reaction Mixture Karr Extractor Feed Recovered Catalyst Stream... 

Karr and Lo [63] have developed sin jle scaling rules for the Karr extractor. To scale HETS from one column size to another, requires that the plate spacing, amplitude, and total volumetric flow rate per unit area be kept the same for each extractor. They foimd for a high interfacial-tension system such as the o-xylene, acetic-acid, water system, that... 

Equations 6.31 to 6.33 have been successfiilly used to scale many Karr extractors from pilot plant experiments to commercial scale extractors up to 1.53 m (5.02 ft) in diameter [61]. 

To complete sizing the Karr column requires sizing the electric motor. The size of the electric motor to disperse one of the phases is small. Walas [51] states that a 1.5 hp (1.12 kW) motor is sufficient to agitate a Karr extractor 30 in (0.762... 

To illustrate the procedure for sizing a Karr extractor, we will use a process design described by Drew [69]. The design requires separating a solution of methylene chloride and methanol. The first step in the process is to contract. 

One of the chief characteristics of the Karr column is its high-volumetric efficiency when compared to other extractors. Volumetric-efficiency is defined as ... 

Karr, Holmes, and Cusack have given comparisons of the Karr column volumetric efficiency with other types of extractors. In Table 15-10 are data showing the values of HETS and volumetric efficiency over a range of column diameters from 1-36 in (0.025-0.9 m) Fig. 15-51... 

As with the other extractors, the final design of a Karr column depends on the scale-up from a pilot test. The following procedure is recommended. 

Figure 11 Agitated extractors. Left to right RDC, Karr, Oldshue-Rushton, Scheibel, Kuhni extraction columns. 

Table 6.31 Minimum HETS and Volumetric Efficiency for the Karr, Recip-rocating-Plate Extractor (Source Ref. 61 with permission). 

Table 6.32 Summary of Equations for Sizing the Karr, Reciprocating-Plate Extractor...

The HETS for an extractor can be estimated by using the scaling rules developed by Karr and Lo [62] and experimental values of HETS summarized in Table 6.31. First, determine if the extraction system is a low interfacial-tension system or a high interfacial-tension system. Next, select a value of HETS from Table 6.31 from the following systems ... 

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