Application of the “three-in-one” two-column tower for aqueous urea solutions

The “three-in-one” two-stage tower combines the heater, distillation tower, and separator together, which saves on piping and reduces space requirements. This leads to a shorter process flow, thereby reducing the amount of biuret generated in the system and lowering the likelihood of pipeline blockages. It is simple to operate and effective； The operational flexibility is low; especially in the distillation and separation sections, where the space is limited, liquid carryover is likely to occur.

In the full-circulation aqueous solution process for urea, the binary towers seem to consist of a \"heater, a distillation tower, and a separator\" connected together – is this what is meant by a \"three-in-one\" design? What was the original binary tower like? Could the poster give some details?

In some systems, the binary tower heaters are separate, while the distillation section and the separation section are integrated.

The so-called \"three-in-one\" two-stage tower was first applied in the small urea production plant with an annual capacity of 40,000 tons, designed by the Fourth Research Institute in the early 1980s; it combined the low-pressure decomposition tower and the low-pressure decomposition heater of the former Zhongshi Fertilizer Plant into one unit, with the distillation section and separation section of the original low-pressure decomposition tower being integrated together. Due to the small scale of the designed urea plant, the size of this tower is also small; therefore, it has been designed in a \"three-in-one\" format, featuring a small footprint and a compact structure. As mentioned on the second floor, this tower is prone to liquid carryover. The reason for this is that the design of other equipment in the small-scale urea production facility includes large margins of safety; meanwhile, the expansion of urea production occurs at a rapid pace and to a significant extent, which leads to the aforementioned problem. According to current chemical separation analysis, the gas distributor and the space allocated for the separation section in the original design of this tower had defects, which resulted in low separation efficiency and a tendency to carry liquid along. However, the \"three-in-one\" design concept of this tower is ingenious; after improvements, there have been significant enhancements in terms of structure, simulation calculations, and separation efficiency, yielding good performance. This post was last edited by lxq700918 on 2009-4-6 11:31.]

The “three-in-one” two-stage tower combines the heater, distillation tower, and separator together, which saves on piping and reduces space requirements. This leads to a shorter process flow, thereby reducing the amount of biuret generated in the system and lowering the likelihood of pipeline blockages. It is simple to operate and effective； Operational flexibility is limited; especially in the distillation and separation sections, where the space is limited, liquid entrainment is likely to occur

According to available information, the \"three-in-one\" two-stage tower was actually proposed by Xiao Zhimin, an expert in urea production from the former Fourth Research Institute. Its structure consists of a distillation section in the upper part, a falling-film heat utilization section in the middle part, and a steam heating section in the lower part. Currently, the aqueous urea production plants of domestic enterprises in Shandong are using this “three-in-one” two-column design; it’s just not clear what the results of using it are Please have someone who is aware of the situation explain it.

In our plant, the distillation section and the separation section are integrated, while the reboiler of the double column is separate.