Differential Distillation:
It is a batch and a single stage distillation that starts with a still pot, initially full, heated at a constant rate. In this process the vapor form on boiling the liquid is removed at once from the system. Since this vapor is richer in the more volatile component than the liquid, it follows that the liquid remaining becomes steadily weaker in this component, with the result that the composition of the product progressively becomes weaker in more volatile component (i.e, impurity starts dominating).
The special distinction of differential distillation is that whilst the vapor formed over a short period is in equilibrium with the liquid, the total vapor formed is not in equilibrium with the residual liquid. Then, at the end of the process the liquid that remains (and is concentrated in less volatile component) is removed as bottom product.
Flash / Equilibrium Distillation:
This is type of distillation is the continuous process. It's main distinction is that the definite fraction of the liquid feed is vaporized in such manner that the vapor must be "in equilibrium" with the residual liquid. Hence called "equilibrium distillation".
The feed is usually pumped through a fired heater but is still a liquid and not in vapor phase. This feed enters the still through a valve where the pressure is reduced. This sudden reduction in pressure reduces the boiling point of the feed. The hot feed becomes vaporized at once as it passes through the valve (hence also named "flash distillation") and enters in the still. The still is essentially a separator in which the partly liquid and vapor produced by the reduction in pressure have sufficient time to reach equilibrium. The vapor is removed from the top of the separator and is then usually condensed, while the liquid leaves from the bottom.
Rectification:
In the two process above, the vapor produced in still is in equilibrium with the liquid remaining, but only a small increase in concentration of more volatile component is achieved. Major distinction b/w rectification and the above two distillation processes lies here, that this process achieves comparatively more
It is a batch and a single stage distillation that starts with a still pot, initially full, heated at a constant rate. In this process the vapor form on boiling the liquid is removed at once from the system. Since this vapor is richer in the more volatile component than the liquid, it follows that the liquid remaining becomes steadily weaker in this component, with the result that the composition of the product progressively becomes weaker in more volatile component (i.e, impurity starts dominating).
The special distinction of differential distillation is that whilst the vapor formed over a short period is in equilibrium with the liquid, the total vapor formed is not in equilibrium with the residual liquid. Then, at the end of the process the liquid that remains (and is concentrated in less volatile component) is removed as bottom product.
Flash / Equilibrium Distillation:
This is type of distillation is the continuous process. It's main distinction is that the definite fraction of the liquid feed is vaporized in such manner that the vapor must be "in equilibrium" with the residual liquid. Hence called "equilibrium distillation".
The feed is usually pumped through a fired heater but is still a liquid and not in vapor phase. This feed enters the still through a valve where the pressure is reduced. This sudden reduction in pressure reduces the boiling point of the feed. The hot feed becomes vaporized at once as it passes through the valve (hence also named "flash distillation") and enters in the still. The still is essentially a separator in which the partly liquid and vapor produced by the reduction in pressure have sufficient time to reach equilibrium. The vapor is removed from the top of the separator and is then usually condensed, while the liquid leaves from the bottom.
Rectification:
In the two process above, the vapor produced in still is in equilibrium with the liquid remaining, but only a small increase in concentration of more volatile component is achieved. Major distinction b/w rectification and the above two distillation processes lies here, that this process achieves comparatively more
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