The continuous vacuum distillation of Dipropylene Glycol Sds adopts three-column linkage operation, which has high efficiency, low energy consumption, and stable quality of finished products. The specific operation is as follows.
1. Operation of the propylene glycol rectification tower The synthesized dipropylene glycol crude product (DPG and TPG content is about 50% and 10%) is pumped to the horizontal tank of the propylene glycol rectification tower, and the gas phase enters the propylene glycol rectification tower after being heated and evaporated. Vertical kettle, the catalyst is enriched in the horizontal kettle, and regularly returned to the catalyst storage tank for recycling, and the propylene glycol at the top of the tower is returned to the synthesis system. Control the steam pressure of the horizontal kettle at 0.6~0.7MPa, control the steam pressure of the vertical kettle at 0.6~0.7MPa, the vacuum degree in the tower is -98kPa, the reflux ratio is 3~4, and the temperature at the top of the tower is controlled at At about 110°C, the content of propylene glycol obtained at this time reaches 99%. The temperature of the vertical kettle is controlled at about 135°C, the content of propylene glycol is <0.2%, the contents of Dipropylene Glycol Sds and tripropylene glycol are about 86% and 13% respectively, and the mixture is pumped to the middle tank of the kettle.
2. Operation of the Dipropylene Glycol Sds rectification tower The mixed material is pumped to the dipropylene glycol rectification tower (the feeding position is fed from the middle of the tower). The vapor pressure of the boiler is controlled at about 0.7MPa, the vacuum degree in the tower is -99kPa, the top of the tower is used for total reflux or intermittent light removal (when the content of propylene glycol in the mixed material is > 0.5), and the temperature in the tower reaches 135°C Dipropylene glycol products are produced from left and right, the content can reach more than 99.5%, and the comprehensive sample of finished products can be guaranteed at about 99.7%. The temperature of the tower kettle is controlled at about 170°C, the content of Dipropylene Glycol Sds is less than 5%, and the mixed material is pumped to the middle tank of the kettle.
3. The operation of the tripropylene glycol rectification tower The mixed material is pumped to the tripropylene glycol rectification tower (the feed position is fed from the middle of the tower). The steam pressure is controlled at about 0.8MPa, the vacuum degree in the tower is -99kPa, the reflux ratio at the top of the tower is controlled to 4-5, and the middle temperature reaches about 160°C to produce the finished tripropylene glycol with a content of more than 99%. The heavy components in the tower kettle are regularly exported to the intermediate tank after being enriched.
The three-tower continuous industrial vacuum distillation production of Dipropylene Glycol Sds is easy to operate, avoids the links of feeding, heating, lightening, etc., and saves a lot of time; the content of each point in the operation process is guaranteed, and the material is integrated The separation effect is good, the quality of the finished product is improved; the output is increased, and the energy consumption is reduced. It can be seen that compared with the three-tower intermittent vacuum distillation, the three-tower continuous vacuum distillation has absolute advantages, and will definitely become the first choice for the industrial vacuum distillation of Dipropylene Glycol Sds.
