Why is the vacuum poor in the vacuum distillation tower?

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This article analyzes the reasons for the poor vacuum condition in distillation towers from multiple aspects. I. Pipeline leaks: Pipeline leaks can cause a sharp drop in the vacuum level of the distillation tower. There are two main reasons for this: on one hand, pipeline leaks allow gas to enter the distillation tower, increasing the internal pressure ； On the other hand, pipeline leaks can cause gas to escape from the top of the distillation tower, resulting in a sharp drop in the vacuum level inside the tank, preventing the desired vacuum level from being maintained. II. Plate clogging: During the distillation process, scaling and carbon deposition can easily occur on the plates, leading to the blockage of their pores and thereby affecting the proper operation of the distillation tower. When the holes in the tray are blocked, it affects the flow of gas inside the distillation tower, impairs the efficiency of distillation separation, and results in a decline in the quality of the distilled product. If not cleaned in time, more and more plate holes will become blocked, affecting the normal operation of the distillation tower. III. Damaged trays: The trays are damaged. Damage to the tray plates reduces the efficiency of the distillation tower; at the same time, it puts pressure on the packing and other equipment located below the tray plates, leading to further damage. The damage to the tray can be caused by excessive negative pressure, or by factors such as equipment aging, corrosion, and damage. If not repaired in time, it may lead to the complete destruction of the tray, resulting in significant losses. IV. Tube Corrosion: Tube corrosion is primarily caused by chemical reactions such as acid corrosion and alkali corrosion that occur due to the media present at the bottom of the tower and on the tray surfaces during the production process. These reactions lead to corrosion and rusting on the surface of the tubes, thereby affecting the vacuum level of the distillation tower. If not addressed promptly, it may lead to the rupture of the tubes, affecting the safety of the entire distillation tower. V. Is the operation of the tower top condenser normal? Fluctuations in the refrigerant temperature cause fluctuations in the gas-phase load of the tower; if the condenser is unable to fully reduce the temperature for complete condensation, it functions more like a sub-condenser, and the aforementioned phenomena will occur. In such cases, considering a slight reduction in the refrigerant temperature may be advisable. VI. Blockage in vacuum pipelines: A blockage in the vacuum pipelines can directly lead to a decrease in vacuum level. These pipelines are usually insulated using hot water or steam, but uneven heating or poor insulation can cause blockages, resulting in poor vacuum conditions. Therefore, it is necessary to check the insulation of the vacuum pipelines, as well as the supply pressure and temperature of the hot water or steam pipelines, and to ensure that the steam traps are functioning properly. VII. Vacuum pump failures: When steam flows through the nozzle of a steam jet pump, pressure is primarily converted into kinetic energy. A significant pressure difference exists between the pressure inside the pump and the pressure at the outlet, which allows the working steam to flow smoothly through the pipes. However, over time, the nozzle is subjected to high-speed flow of steam, leading to wear on it; this in turn can cause unstable operation of the vacuum pump. VIII. Changes in feed composition: Fluctuations in the amount of feed or its temperature can also cause fluctuations in vacuum; this requires inspection and analysis of the process materials or the feed valves. In short, the poor vacuum in a distillation tower is not caused only by the eight factors mentioned above; other issues such as improper operation and equipment aging can also lead to problems. To ensure production safety, companies need to regularly maintain and inspect distillation towers in order to identify and resolve issues promptly.