Total reflux is a condition in distillation where the entire liquid leaving the condenser is returned to the top of the column as reflux. In other words, the reflux ratio is defined as the ratio of the liquid returning to the column as reflux to the liquid leaving the column as product.

Reflux Ratio and its Types:
The reflux ratio can take different values depending on the operating conditions of the distillation column. These values include total reflux, minimum reflux, and part reflux.

1. Total Reflux:
Total reflux occurs when all the liquid leaving the condenser is returned to the top of the column as reflux. This means that no liquid is withdrawn as product from the column. In this case, the reflux ratio is essentially infinity, as there is an infinite amount of reflux compared to the product flow rate.

Total reflux is often used at the beginning of a distillation process to establish a steady-state condition and to establish the desired composition profile within the column. It is also used in laboratory-scale distillations for analytical purposes.

2. Minimum Reflux:
Minimum reflux is the minimum amount of reflux required to achieve the desired separation in a distillation column. It is the lowest reflux ratio that still allows for the separation of the desired components. Operating at minimum reflux can be more economically favorable as it reduces the energy consumption of the distillation process.

3. Part Reflux:
Part reflux refers to any reflux ratio between the total reflux and the minimum reflux. It means that only a portion of the liquid leaving the condenser is returned to the column as reflux, while the remaining portion is withdrawn as product. Part reflux is commonly used in industrial distillation processes to achieve the desired separation with a reasonable energy requirement.

Conclusion:
In summary, the reflux ratio of infinity corresponds to the condition of total reflux, where all the liquid leaving the condenser is returned to the top of the distillation column as reflux. Total reflux is often used to establish steady-state conditions and desired composition profiles within the column. On the other hand, minimum reflux is the minimum amount of reflux required for separation, and part reflux refers to any reflux ratio between total reflux and minimum reflux.