Material balance, stages recovery

Analytical models using classical reservoir engineering techniques such as material balance, aquifer modelling and displacement calculations can be used in combination with field and laboratory data to estimate recovery factors for specific situations. These methods are most applicable when there is limited data, time and resources, and would be sufficient for most exploration and early appraisal decisions. However, when the development planning stage is reached, it is becoming common practice to build a reservoir simulation model, which allows more sensitivities to be considered in a shorter time frame. The typical sorts of questions addressed by reservoir simulations are listed in Section 8.5. 

This chapter will focus on a unique problem encountered during recovery of intracellulary produced proteins. Disruption of cells produces a mixture of nucleic acids and proteins in the solution from which the desired proteins must be fractionated. Typical separation schemes involve first the removal of nucleic acids from solution by precipitation. The desired protein is then isolated and purified from the mixture of remaining nucleic acids and proteins. A scheme for recovery of intracellular bacterial enzyme tartrate dehydrogenase from cell paste is shown in Fig. 1. Material balance at the different stages of the scheme in two different experiments showed that 53-60% loss in enzyme activity took place during precipitation of nucleic acids by protamine sulfate and during ammonium sulfate fractionation of proteins (Table 2). Reduction in volume, removal of major nonprotein... 

IH TABLE 2 Material Balance at Different Stages of Recovery of Tartrate Dehydrogenase from Cell Paste... 

For more precise values, computer programs can be used to calculate soluble recovery as well as solution compositions for conditions that are typical of a CCD circuit, with varying nnderflow concentrations, stage efficiencies, and solution densities in each of the stages. The calculation sequence is easily performed by utilizing material-balance equations around each thickener. 

The material balance for the first cycle of operation in the present study is shown in Figure 42.12. The present material balance shows a total input of 12 m of 10% NaSCN feed containing 3% impurities. A total amount of 18.4 m of DM water is added for dilution of feeds during the five stages from cycle 2 onwards. The ouqDut product is 21.6 kg of 3.6% NaSCN, which is fi ee of color and contains only 0.06% of impurities since a dilution of 1 1.5 is employed from Stage II onwards. The other output is a final reject quantity of 4.8 m containing <0.1% NaSCN and 4.7% impurities for disposal. The total NaSCN recovery is 99.4% and impurity rejection 94.2%. 

Since the system is binary, the two recovery specifications determine the total product rates by overall material balance. With the total number of stages fixed, the reflux ratio required to achieve the desired separation depends on the feed locations. It is desirable to operate the column at the lowest possible reflux ratio in order to minimize the condenser and reboiler duties. 

Designing a column usually starts with heat and material balance calculations, preferably using a computer simulation program. These calculations determine the liquid and vapor flow rates and the number of equilibrium stages required to meet the design performance specifications (separation, recovery, etc.). Fluid properties, such as densities and viscosities, may also be generated by the computer program. 

The combination of an absorption cascade topped by a condenser is referred to as an enricher. A partial reboiler topped by a stripping cascade is referred to as an exhauster. As shown in Fig. 12.25 stages for an enricher are numbered from the top down and the overhead product is distillate, while for an exhauster stages are numbered from the bottom up. Feed to an enricher is vapor, while feed to an exhauster is liquid. The recovery equations for an enricher are obtained from (12-64) by making the following substitutions, which are obtained from material balance and equilibrium considerations. 

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