Purification Technology Q&A Version [004]

1. Maintain an appropriate gas-liquid ratio. 2. Ensure that the levelness of the tower trays is satisfactory. 3. There should be no leakage from the tower trays. 4. The absorbent must have a high purity. 5. The tower trays must be clean and free from contaminants, with the liquid layer thickness maintained.

1. Maintain an appropriate gas-liquid ratio. 2. Ensure the trays are level as required. 3. There should be no leakage from the trays. 4. The absorbent must have high purity. 5. The trays must be clean and free of contaminants, with the liquid layer thickness maintained.

1. Maintain an appropriate gas-liquid ratio. 2. Ensure the trays are level as required. 3. There should be no leakage from the trays. 4. The absorbent must have high purity. 5. The trays must be clean and free of contaminants, with the liquid layer thickness maintained.

1. Use high-efficiency trays； 2. Increase the liquid flow length on the tray ； 3. Reduce the flow width ； 4. Increase the height of the outlet weir.

1. Maintain an appropriate gas-liquid ratio. 2. The levelness of the tower trays must be satisfactory. 3. There should be no leakage from the trays. 4. The absorbent must have high purity. 5. The trays must be clean and free from contaminants, with the liquid layer thickness maintained.

There are mainly the following methods to improve the separation efficiency of the tower: (1) Improve the efficiency of the trays. Measures to improve tray efficiency include, in addition to using high-efficiency trays, mainly making minor improvements to existing trays. Another practical technical measure to improve tray efficiency is to increase the contact area between the gas and liquid phases on the tray as well as the residence time of the liquid phase, which can be achieved through any combination of the following three measures: ① Increasing the length of the liquid flow on the tray. ②Reduce the flow width. ③Increase the height of the outlet weir. In recent years, several new types of high-efficiency trays have been developed in China, which can be considered for use in newly built plants or during major renovations of existing ones. However, for most distillation units, the more economical approach is (2) to increase the number of theoretical plates. Under the specified tray type, product purity, and operating pressure, the separation efficiency that a distillation column can achieve is a function of the number of trays and the reflux ratio. Therefore, when the tray efficiency is similar, only by increasing the number of trays can the reflux ratio be reduced to achieve energy savings. For newly built or renovated atmospheric and vacuum distillation units, the number of trays in the atmospheric tower should be increased, particularly those at the lower part of the tower, in order to improve the distillation accuracy of the atmospheric tower. The current trend in the development of atmospheric pressure columns is an increasing number of trays and a continuous improvement in tray efficiency. The distillation section of the newly designed atmospheric tower should have no fewer than 50 trays; increasing the number of trays appropriately results in a modest increase in investment, but yields very significant benefits. (3) Reduce the operating pressure of the tower. Since low pressure can improve the relative volatility of the components being separated in the distillation column, reducing the operating pressure in the column allows the reflux ratio to be decreased while still achieving the same separation efficiency. Furthermore, reducing the tower pressure also enables achieving the same vaporization fraction at a lower furnace exit temperature. However, in practice, reducing the column pressure may be limited by various factors; for example, a atmospheric pressure column may be constrained by the capacity of the overhead condensation system (such as air coolers), while a vacuum system may be limited by the capacity and efficiency of the vacuum pump as well as the pressure drop across the trays. (4) Improve the stripping efficiency of the stripping section and the side-line stripper. The stripping efficiency in the stripping section of the atmospheric pressure tower directly affects the content of the 350qC fraction in the heavy crude oil at the bottom of the tower ； The stripping efficiency of the stripper for the side-stream product directly affects the amount of light components carried by that side-stream product. It is necessary to adjust and optimize the amount of stripping steam in a timely manner according to changes in crude oil varieties and product plans, in order to improve the stripping efficiency. (5) Apply Advanced Process Control (APC) technology. During production operations, different teams and operators achieve varying degrees of distillation precision and product yields, which reflects the significant impact of process operations. The application of APC technology, which relies primarily on multi-variable predictive control (RMPCT), can effectively improve operational performance.

There are mainly the following methods to improve the separation efficiency of the tower: (1) Improve the efficiency of the trays. Measures to improve tray efficiency include, in addition to using high-efficiency trays, mainly making minor improvements to existing trays. Another practical technical measure to improve tray efficiency is to increase the contact area between the gas and liquid phases on the tray as well as the residence time of the liquid phase, which can be achieved through any combination of the following three measures: ① Increasing the length of the liquid flow on the tray. ②Reduce the flow width. ③Increase the height of the outlet weir. In recent years, several new types of high-efficiency trays have been developed in China, which can be considered for use in newly built plants or during major renovations of existing ones. However, for most distillation units, the more economical approach is (2) to increase the number of theoretical plates. Under the specified tray type, product purity, and operating pressure, the separation efficiency that a distillation column can achieve is a function of the number of trays and the reflux ratio. Therefore, when the tray efficiency is similar, only by increasing the number of trays can the reflux ratio be reduced to achieve energy savings. For newly built or renovated atmospheric and vacuum distillation units, the number of trays in the atmospheric tower should be increased, particularly those at the lower part of the tower, in order to improve the distillation accuracy of the atmospheric tower. The current trend in the development of atmospheric pressure columns is an increasing number of trays and a continuous improvement in tray efficiency. The distillation section of the newly designed atmospheric tower should have no fewer than 50 trays; increasing the number of trays appropriately results in a modest increase in investment, but yields very significant benefits. (3) Reduce the operating pressure of the tower. Since low pressure can improve the relative volatility of the components being separated in the distillation column, reducing the operating pressure in the column allows the reflux ratio to be decreased while still achieving the same separation efficiency. Furthermore, reducing the tower pressure also enables achieving the same vaporization fraction at a lower furnace exit temperature. However, in practice, reducing the column pressure may be limited by various factors; for example, a atmospheric pressure column may be constrained by the capacity of the overhead condensation system (such as air coolers), while a vacuum system may be limited by the capacity and efficiency of the vacuum pump as well as the pressure drop across the trays. (4) Improve the stripping efficiency of the stripping section and the side-line stripper. The stripping efficiency in the stripping section of the atmospheric pressure tower directly affects the content of the 350qC fraction in the heavy crude oil at the bottom of the tower ； The stripping efficiency of the stripper for the side-stream product directly affects the amount of light components carried by that side-stream product. It is necessary to adjust and optimize the amount of stripping steam in a timely manner according to changes in crude oil varieties and product plans, in order to improve the stripping efficiency. (5) Apply Advanced Process Control (APC) technology. During production operations, different teams and operators achieve varying degrees of distillation precision and product yields, which reflects the significant impact of process operations. The application of APC technology, which relies primarily on multi-variable predictive control (RMPCT), can effectively improve operational performance.

1. Maintain an appropriate gas-liquid ratio. 2. The levelness of the tower trays must be satisfactory. 3. There should be no leakage from the tray surfaces. 4. The absorbent should have a high purity. 5. The trays must be clean and free from contaminants, with a consistent liquid layer thickness

1. Maintain an appropriate gas-liquid ratio. 2. The levelness of the tower trays must be satisfactory. 3. There should be no leakage from the tray surfaces. 4. The absorbent should have a high purity. 5. The trays must be clean and free from contaminants, with a consistent liquid layer thickness

1. Maintain an appropriate gas-liquid ratio. 2. The levelness of the tower trays must be satisfactory. 3. There should be no leakage from the tray surfaces. 4. The absorbent should have high purity. 5. The trays must be clean and free from contaminants, with a consistent liquid layer thickness