Distillation tower top reflux system and distillation tower top reflux method

Abstract

The invention relates to a distillation tower top reflux system and a distillation tower top reflux method. The system comprises a distillation tower, a reflux pump and an air cooler, wherein the topportion of the distillation tower is provided with a temperature display and control device 1, the upper portion of the distillation tower is sequentially provided with spraying devices, tower platesand a tower breaking disc from top to bottom, one side of the tower body above the liquid discharge channel of the tower breaking disc is provided with a condensate recovery port, the condensate recovery port is connected to a spraying liquid pipeline through a condensate pipeline outside the distillation tower, the reflux pump and the air cooler are sequentially arranged on the condensate pipeline along a condensate flowing direction, the tower body below the tower breaking disc is provided with a reflux liquid inlet, the reflux liquid inlet is connected to the condensate pipeline on the downstream of the reflux pump through a reflux liquid pipeline outside the distillation tower, and the condensate pipeline on the downstream of the air cooler is connected to a product recovery pipeline on the tower top. According to the present invention, with the system and the method, the problem that the circulating water pipe diameter of the internal reflux method is too large so as not to easilysupport can be avoided, and the reflux rate of the top of the tower can be precisely controlled; and the system and the method are particularly suitable for large-scale distillation process systems.

Description

technical field [0001] The invention relates to the technical field of distillation and purification in tar processing and benzene hydrogenation process, in particular to a reflux system and method at the top of a distillation tower. Background technique [0002] At present, the small-scale distillation process adopts the external reflux method, that is, the gas phase material evaporated from the top of the distillation tower is cooled in the condensing cooler and then enters the reflux tank, and is pumped out by the reflux pump. Part of the material returns to the top of the tower as reflux, and the other part Material is extracted. The reflux flow is controlled according to the temperature at the top of the tower, and the output is controlled according to the liquid level of the reflux tank. [0003] As the distillation scale increases, the diameter of the gas phase outlet pipe at the top of the distillation tower also increases. Due to the high outlet temperature at the ...

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Problems solved by technology

[0003] As the distillation scale increases, the diameter of the gas phase outlet pipe at the top of the distillation tower also increases. Due to the high outlet temperature at the top of the tower, if the gas phase pipe diameter is too large, the expansion will also increase, which is not conducive to the support at the support. Stress analysis and structural design; for construction, it is not conducive to installation, and the construction cost is high

[0004] Therefore, the current large-scale distillation process basically adopts the internal reflux control method, that is, the overhead condenser is directly placed on the top of the distillation tower, and the gaseous phase material at the top of the tower is condensed and then flows back into the tower. Although this method can solve the above-mentioned problems, it cannot Precisely control the return flow at the top of the tower, especially if the top condenser is directly placed on the top of the distillation tower, the circulating water pipe needs to be led from the pipe gallery to the top condenser. Taking a distillation tower with a height of 45 meters as an example, the circulating water The diameter of the pipe will reach DN400. Such a large-diameter pipe stands tens of meters high, which is not conducive to support and fixation. Especially when there is no frame above a certain height in the upper part of the distillation tower, it can only be fixed by welding the bracket on the tower wall. This method has great risks, and the input cost of large-diameter pipelines is also high

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