Questions about distillation

Possible reasons: A low reflux ratio, too few trays in the distillation section, flooding, low tray efficiency, improper temperature control, and so on, can all lead to substandard product quality.

How can we determine what the cause is?

What product? Without the specifications, can they help determine what the cause is?

The common reason for this is improper adjustment of the reflux ratio. The stage where the problem occurred should be identified by analyzing the purity of the intermediate materials ； Furthermore, all parameters should be strictly controlled within their set ranges.

The top of the tower or the bottom? Was it unqualified from the start of testing, or during operation? How can it be made clear if it’s not described properly?

It would be best if the poster could list your process parameters so that a targeted analysis can be carried out.

There are three ways to obtain the product from a distillation tower: from the top, from the bottom, or from the middle. For these three cases, the reasons for substandard product quality are different. 1. If the product at the top of the tower is of poor quality, the following parameters are usually adjusted: the reflux ratio or the amount of product taken from the top of the tower, the temperature and pressure at the top of the tower, the number of trays in the distillation section (the feeding position), and the amount of feed. 2. If the product at the bottom of the tower is of poor quality, the following factors are usually considered: the amount of product taken from the bottom of the tower, the temperature and pressure at the bottom of the tower, the number of trays in the stripping section, and the amount of feed. 3. If the quality of the product taken from the middle part of the tower is poor, the following factors are usually considered: the temperature and pressure in that middle section, the amount of feed, and the feeding position

It’s best to write down the parameters so that everyone can analyze them

Your question is too general, and it doesn’t seem like that of a professional. There are many reasons for poor quality, which need to be analyzed one by one. 1. Is it due to the design of the tower? If that’s the case, then no matter what you do, it will be impossible to achieve a satisfactory quality. The best approach is to invite a design institute with extensive expertise to carry out the design during the initial stage of facility construction. 2. Do not be afraid to spend money on project construction; have the design institute provide a turnkey solution, and pay only after qualified products are produced. Otherwise, the design institute will have to take responsibility. 3. The installation of components inside the tower has a significant impact on product quality; if there are issues with the installation, it is difficult for the quality to meet standards. 4. The actual operation of distillation is complex, but the specific operating parameters are limited to just a few, and these need to be explored step by step.