Extraction of butadiene by acetonitrile method

As the concentration of 1,3-butadiene in the feed increases, the load on the distillation column rises, which means that more trays and/or a higher reflux ratio are required to achieve the desired separation. 1. Change in the number of trays: Generally, when the proportion of heavy components in the feed increases, it may be necessary to increase the number of trays in order to achieve the same separation effect. This is because each tray provides a certain degree of gas-liquid equilibrium stage, and more trays mean better contact and separation effects. 2. Change in reflux ratio: After increasing the feed concentration, it is usually necessary to raise the reflux ratio to ensure sufficient separation efficiency. An increase in the reflux ratio can enhance the repeated gas-liquid contact within the tower, thereby improving separation efficiency. 3. Changes in the control parameters at the top and bottom of the tower: As the feed concentration increases, and while the purity requirement for the product at the top of the tower remains unchanged, it may be necessary to adjust the temperature and pressure at that point in order to maintain the specified properties of the product. At the same time, the composition of the material in the bottom of the tower also changes, and it may be necessary to adjust the heating method or the flow rate at the bottom of the tank in order to maintain stable operation. Overall, increasing the concentration of 1,3-butadiene in the feed will require adjustments to the distillation process, including increasing the number of trays, raising the reflux ratio, and adjusting the operating parameters at the top and bottom of the tower to ensure product quality and operational stability. .

I. Analysis of desolvent concentration: In the acetonitrile method for extracting butadiene, acetonitrile serves as the solvent, and its concentration has a significant impact on the distillation efficiency. As the concentration of 1,3-butadiene in the feed increases, the solvation and selective extraction of 1,3-butadiene by the solvent acetonitrile change. To maintain a stable separation effect, it may be necessary to adjust the concentration of the solvent acetonitrile. Solvent recovery tower: During the solvent recovery process, by adjusting the concentration of the recovered acetonitrile, it is possible to control the amount of water that enters the solvent system, thereby stabilizing the water content of the solvent. As the concentration of 1,3-butadiene in the feed increases, it may be necessary to raise the concentration of recovered acetonitrile in order to reduce the amount of water entering the solvent system and maintain the stability and selectivity of the solvent. Circulating solvent system: In a circulating solvent system, the concentration of the solvent acetonitrile also needs to be strictly controlled. As the concentration of 1,3-butadiene in the feed increases, it may be necessary to increase the flow rate of the solvent acetonitrile to enhance its extraction capacity for 1,3-butadiene. At the same time, the concentration of the solvent acetonitrile can be further controlled by adjusting the operating parameters of the solvent recovery tower, such as the top temperature of the tower. II. Changes in control parameters at the tower top and bottom: In the distillate at the tower top: As the concentration of 1,3-butadiene in the feed increases, the amount of 1,3-butadiene in the distillate at the tower top may also increase. To ensure the quality of the overhead distillate, it may be necessary to adjust the operating parameters of the tower, such as temperature and pressure. At the same time, it is necessary to increase the reflux flow rate to maintain a constant reflux ratio, thereby ensuring that the proportions of various components in the overhead distillate meet the required standards. However, excessive reflux flow can lead to increased energy consumption and reduced tray efficiency; therefore, it is necessary to find the optimal reflux ratio. Reactor bottom distillate: The reactor bottom distillate mainly contains the unextracted heavy components and the solvent acetonitrile. As the concentration of 1,3-butadiene in the feed increases, the amount of 1,3-butadiene in the bottom distillate may decrease, as more 1,3-butadiene is extracted to the top of the tower. To ensure the quality of the bottom stream from the tower, it may be necessary to adjust the operating parameters of the tower bottom, such as the amount of heating steam and the amount of solvent fed in. At the same time, it is necessary to regularly analyze the composition of the bottom fraction from the tower to ensure that it meets the production requirements. III. Changes in the number of plates and the reflux ratio. Number of plates: The number of plates is one of the important parameters in the design of distillation columns. As the concentration of 1,3-butadiene in the feed increases, it may be necessary to increase the number of tower plates to improve separation efficiency. However, increasing the number of trays raises equipment costs and energy consumption, so a comprehensive consideration is required. In practical operations, the separation efficiency can be optimized by adjusting the temperature and pressure distribution across the tray. For example, the separation efficiency can be improved by increasing the heat transfer area on the trays or by optimizing the heat transfer method. Reflux ratio: The reflux ratio is an important operational parameter in the distillation process. It represents the ratio of the amount of return fluid to the amount of produced fluid. As the concentration of 1,3-butadiene in the feed increases, the reflux ratio may need to be adjusted in order to maintain a constant separation efficiency. Generally, increasing the reflux ratio can improve the purity of the overhead distillate, but it also increases energy consumption and the load on the tray. Therefore, it is necessary to find the optimal reflux ratio to balance the relationship between separation efficiency and energy consumption.