How do you find the minimum reflux ratio from McCabe Thiele?

Minimum Reflux Ratio (Rm) Solving above equations gives a quadratic expression, which is solved for positive roots. Draw a line from ( xD, yD) passing through ( x1, y1) with an intercept xD / (Rm + 1) on Y axis. Reflux ratio is calculated as 1.5 times the minimum reflux ratio.

How do you find the minimum reflux ratio?

The reflux ratio is defined as the ratio of the liquid returned to the column divided by the liquid removed as product, i.e., R = Lc/D.

How do I choose optimum reflux ratio?

The total cost, which is the sum of fixed cost and operating cost, must therefore passes through a minimum. The reflux ratio at this minimum total cost is the optimum (or economical) reflux ratio. Typically the optimum reflux ratio is approximately 1.2 to 1.5 times Rmin.

Which of the following is true for minimum reflux ratio?

For minimum reflux ratio the number of trays becomes infinite. Explanation: For minimum reflux ratio, all the condensed vapour becomes distillate; no reflux. So it requires infinite number of trays. 6.

What is reflux ratio at total reflux?

The Reflux ratio is the ratio between the boil up rate and the take-off rate. Or in other words, it is the ratio between the amount of reflux that goes back down the distillation column and the amount of reflux that is collected in the receiver (distillate). Instead we call this “total reflux” or equilibration.

Can minimum reflux ratio be less than 1?

As far as I understand there is no limit for reflux ratio if desired specs and economically feasable operation is achieved.

What are the limitations of the McCabe-Thiele method?

A number of shortcomings exist in the McCabe­ Thiele method when it is applied to the cases of subcooled (or superheated) feed: 1. When the feed is a subcooled liquid (or a superheated vapor), on the assumption that Land Dare all constants, the number of theoretical stages tends to a mini­ mum according to the McCabe-Thiele method,

What is the minimum reflux ratio in MiG method?

method, the number of theoretical stages is defined. Minimum Reflux Ratio. The minimum reflux is obtained when the feed line, equilibrium curve and the operating line of the section meet at one point. The minimum reflux is the minimum allowable re­ flux for the separation.

How do you calculate theoretical stages at an actual reflux ratio?

The recommended method to use to determine the actual theoretical stages at an actual reflux ratio is the Erbar/Maddox relationship. In the graph, N is the theoretical stages and R is the actual reflux ratio L/D, where L/D is the molar ratio of reflux to distillate. N, is the minimum theoretical stages and R, is the minimum reflux ratio.

What is the unitless ratio of reflux ratio?

= reflux ratio that requires an infinite number of stages in the rectifying section (unitless) = molar flow rate of vapor within the rectifying section, assumed constant in McCabe-Thiele model (mol time -1)