Balance point determination

FIG. 11 96 Balance points of compressor and condenser determines performance of condensing unit for fixed temperature of condenser cooling fluid (flow rate and heat-transfer coefficient are constant). 

Freezing-point Determination. — I n the example to be described, pure benzene (see p. 136) is used as the solvent. Carefully dry the inner tube. Fit it wuth a cork and weigh it together w ith the coik suspended by a wire to the aim of the balance. Intioduce sufficient benzene to cov er the bulb of the Beckmann thermometer when it is pushed nearly to the bottom of the tube. About 10 c.c. will be found to be sufficient. Insert... 

Our strategy is to first solve the material balance, then determine the tower height. Since we are dealing with dilute solutions we may use the simplified form of the material balance. So for any point in the tower are related by... 

Either the temperatures or flows could be adjusted first. The common choice is to correct the temperature. Correction of temperatures is usually done through either bubble-point or dew-point determinations on the calculated stage compositions. After correcting the stage temperatures, the liquid and vapor enthalpies may be obtained from the calculated compositions, and the flows corrected by solution of the now linear heat balance equations of Table I. 

In order to determine whether the valves are fully open, fully closed or in between, and in order to apply the pressure drop equation between the open and closed balance points, the vapor hole velocities aft each balance point must be evaluated. The balance-point hole velocities are evaluated from a balance between the vapor force pushing the valve open and the gravity force tending to close it. This force balance gives (71,80)... 

Alternative Method of Determining the Balance Point of an Isotope... 

The procedure will therefore be to write overfill s> tem balances to determine m3 and X3, then balances on Unit 1 to determine mi and xi, and finally balances on the intermediate mixing point to determine m2 and X2. 

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