How to adjust the process parameters of a distillation tower?

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How is the pressure in a distillation column adjusted during operation? What are the factors that affect changes in tower pressure? The pressure in the tower is one of the main control parameters for a distillation tower. In the operation of any distillation column, the column pressure must be kept within specified limits in order to adjust other parameters accordingly. Excessive fluctuations in tower pressure can disrupt the material balance and gas-liquid equilibrium throughout the tower, resulting in a product that does not meet the required quality standards. Therefore, many distillation columns have specific measures to ensure that the column pressure remains within an appropriate range. For the tower pressure of the pressurized tower, there are mainly the following two methods of adjustment. ①When the top condenser is a fractional condenser, the column pressure is generally adjusted based on the gas phase withdrawal rate. With all other conditions unchanged, the gas-phase recovery increases and the column pressure decreases ； The gas-phase recovery decreases and the tower pressure rises. ②When the top condenser is a total condenser, the column pressure is usually adjusted by the amount of refrigerant used, which is equivalent to adjusting the temperature of the reflux liquid. With all other conditions remaining unchanged, increasing the amount of cooling agent lowers the temperature of the reflux liquid and reduces the tower pressure ； If the amount of cold fluid is reduced, the temperature of the reflux liquid rises and the tower pressure increases. For the pressure control of a vacuum distillation column, there are mainly the following two methods. ①When the vacuum in the tower is achieved using a jet pump, the vacuum level of the tower can be adjusted by modifying the amount of refrigerant or the temperature of the refrigerant in the top condenser, thereby changing the amount of exhaust gas. When the separated material is allowed to come into contact with air, in this control scheme, the steam jet pump operates at its maximum capacity. A control valve is installed on the pipeline leading to the atmosphere, and by adjusting the opening degree of this valve, the amount of exhaust gas drawn from the system can be controlled, thereby regulating the vacuum level in the tower. ②When using an electric vacuum pump for vacuum creation, a control valve is installed on the return line of the vacuum pump; the degree of opening of this control valve is used to adjust the amount of exhaust gas removed from the system, thereby controlling the vacuum level in the tower.