![]() ![]() This procedure is repeated for additional stages until the raffinate composition is nearly equal to the desired value. ![]() Where this line intersects the left side of the phase boundary is the composition of. Thus, the extract composition leaving stage 2,, is found by drawing a straight line from to (because from the previous equation). This equation is rearranged to define the operating point:Ī tie line from to the right side of the phase boundary yields the raffinate composition leaving stage 1, this line represents the first equilibrium stage (orange).Ī mass balance on stage 1 (total feed in = total feed out) is: The operating point is located at the intersection of a line drawn through points and and a line drawn through and because the overall mass balance for the system is: Ī line drawn from the desired raffinate composition through the mixing point until it intersects the phase boundary gives the extract composition leaving stage 1. Where is the line segment from the mixing point to the feed location, and is the line segment from the mixing point to the solvent location. The mixing point is located on the phase diagram using the lever rule: Here is the combined feed and solvent flow rate (kg/hr) and, and refer to the mass fractions of solute, solvent and carrier in (feed, solvent and mixed ), which is the stream fed to the cascade. Solute : (because the solvent feed contains no solute), The mixing point corresponds to the composition that would be obtained if the feed and the solvent flows were mixed together: First, the mixing point composition is calculated and located on the ternary phase diagram. ![]() The desired raffinate composition is specified, and the extract composition and the number of stages to obtain the desired raffinate composition are determined by mass balances. The feed ( ) flow rate, solvent ( ) flow rate and feed composition (select one of three compositions) are given. For any of the displays, check "show grid" to display grid lines on the ternary diagram. Finally, select "count stages" and move the "draw tie lines" slider to the right to see how to determine the number of stages and show the raffinate composition leaving each stage. This also displays a schematic of the flow system. Next, select "operating point" to see how the operating point ( ) is found. Select "mixing point" to see how the lever rule is used to determine the mixing point ( ), and check "show " to see how the extract composition from the first stage is found. Select "plot points" to display the feed ( ), solvent ( ) or raffinate ( ) on the phase diagram. The solvent mass flow rate is given, and the desired raffinate (refined product) composition is given. Select a feed composition from the drop-down menu. The system contains a solvent, carrier and solute. The Hunter–Nash method uses material balances and a ternary phase diagram with phase separation to determine the number of equilibrium stages needed for liquid-liquid extraction (LLE). ![]()
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