Guidelines for Reuse of an Existing Tower

The guidelines discussed next are mainly recommended by Wankat (1988), and the following things in order of increasing costs, can be explored when the existing column cannot produce the desired product purities  

Find out whether the product specifications can be relaxed. A purity of 99.5% is much easier to obtain than 99.99%. 

Will a new feed stage at the optimal stage allow meeting product specification Consider replacing the existing column internals with more efficient or tighter-spaced trays or new packing. This is relatively expensive but is cheaper than a new column. 

If the column vapor loading is more than the limit implying the existing column diameter is not large enough, engineers can consider  

Operating at a reduced reflux ratio, which reduces vapor loading however, this could make it difficult to meet product specifications  

---