Selection of distillation columns

Packed towers have low resistance and are suitable for low-pressure applications, while tray towers can handle high loads and are appropriate for large-scale projects. However, Air Liquide’s packed towers can also handle high loads with a minimal amplification effect, though they are quite expensive

It would be best to provide specific parameters so that each issue can be analyzed individually

We handle 3-4 tons per day of the separation of mineral base oil from hydrocarbon cleaning agents. Due to our small scale, we currently use existing equipment that consists of a distillation column 2 meters high mounted on a distillation still, followed by a cooler. We now want to operate in a more professional manner and would appreciate some guidance from everyone. Mineral oil is Doudar’s 360B food-grade white oil, while the hydrocarbon cleaner is 103. After separation, activated clay is added to the white oil for decolorization; however, since a significant amount of oil remains in the clay, other methods of adsorption are being considered.

The prominent advantages of packed towers are low resistance to fluid flow, simple structure, less use of steel, low cost, and ease of installation and maintenance. The common types of plate distillation towers include: (1) Tray towers: Their advantage is their simple structure and low gas pressure drop, but their main disadvantages are a narrow operating range and the tendency for the small-pore trays to get clogged. To overcome the disadvantages of sieve plates, they have been continuously improved; for example, to address the issue of high requirements regarding horizontal installation, countercurrent sieve plates were developed ； To overcome the liquid leakage issue of sieve plates at low loads, a sieve plate with disks beneath it was designed ； To reduce foam entrainment on the tray, methods such as reducing the tray spacing, using trays with baffles or perforated designs, replacing the inlet weir with an inclined foam generation platform, and employing Lindström trays with gas guide grooves on the trays have been employed. (2) Bubble column: Advantages include good operational flexibility ； The downside is its complex structure ； The plate pressure drop is high. (3) Floating valve tower: The advantage is its large production capacity ； High operational flexibility ； High tray efficiency ； The gas pressure drop and the liquid level difference are small ； The cost of the tower is low. (4) Guided floating valve tower: Guiding holes are provided at the top of the floating valves, which serve to guide the flow of liquid. (5) Jet-type towers: there are tongue trays, floating jet trays, and floating tongue trays. (6) Mesh tray: A thin metal plate with directional meshes. (7) Cross-flow tray: Lacks an overflow weir; its efficiency is very low, but it is widely used in the distillation of polymers

Learning* learning*, but it doesn’t seem very detailed

One is to consider the performance, and the other is to look at the specific operating conditions and medium.

It depends on your operational flexibility; generally, the minimum load for a sieve plate tower is 70%, as lower loads make it impossible to maintain proper operation and control. While a packed tower can achieve 50%.

Currently, there seems to be a trend toward using packed towers for large-scale air separation.