【Q&A Question 076】March 17, 2017
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This post was last edited by 955559 on 2017-7-21 22:32. [Q&A Question No. 076] 2017.03.17: What is the significance of controlling the bottom temperature of the fractional distillation tower in the distillation process? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) The bottom temperature of the distillation tower is a key indicator of the amount of evaporation that occurs in that tower; a higher temperature corresponds to greater evaporation ； Excessively high temperatures can even lead to entrainment, resulting in a higher dry point and darker color of the side-stream product. However, when the temperature at the bottom of the tower is low, the desired components cannot evaporate; this results in lower-quality product and increased load on the equipment below. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html Third Phase of HaiChuan’s Outstanding Management Members Selection Contest http://bbs.hcbbs.com/thread-1655902-1-1.html (Source: HaiChuan Chemical Forum)
Control of different fractions and product purity
The upper limit of the bottom temperature of the fractionation tower is constrained by coking of the oil at the bottom of the tower, while the lower limit is constrained by the temperature at the convective outlet of the heater and the minimum value of the recycle ratio. If the temperature is too low, it will affect the thermal balance of the entire tower; generally, the temperature at the bottom of the tower is controlled by regulating the temperature in the evaporation section
How to control the bottom temperature of the distillation tower? Answer: The upper limit of the bottom temperature of the distillation tower is determined by coking of the oil at the bottom of the tower, while the lower limit is constrained by the temperature at the convection outlet of the heater and the minimum value of the recycle ratio. If the temperature is too low, it will affect the thermal balance of the entire tower; generally, the temperature at the bottom of the tower is controlled by regulating the temperature in the evaporation section. The factors that affect the bottom temperature of the fractionation tower are: (1) changes in the amount of feedstock. (2) Changes in the distribution of upward and downward reflux. (3) Change in the temperature of the evaporation section. (4) Changes in the temperature of the crude oil. (5) Changes in the temperature of oil and gas entering the tower. (6) Changes in radiation flux. (7) Changes in the liquid level at the bottom of the tower. Corresponding adjustment methods: (1) Identify the cause of changes in raw material quantity and stabilize feeding. (2) Adjust the distribution amounts of the upper and lower refluxes properly. (3) Adjust the temperature of the evaporation section properly. (4) Strengthen communication among various positions and adjust the parameters properly. (5) Use quench oil to adjust the temperature of the oil and gas. (6) Identify the causes of changes in radiation flux and stabilize the flux. (7) Control the amount flowing into the tower and the radiation from the heating furnace.
The bottom temperature of the tower is the main indicator for measuring the amount of evaporation of the material within that tower. High temperature, high evaporation rate ； Excessively high temperatures can even lead to carrying over, resulting in a higher dry point and darker color of the side-stream products. However, when the temperature at the bottom of the tower is low, the desired components cannot evaporate; this results in lower-quality products, which in turn affects the quality of the various side streams as well as the load on the equipment at the bottom of the tower.
It enables a better maintenance of thermal balance； It is possible to control the initial boiling point and flash point of the bottom oil, thereby regulating the quality of the oil product!
The bottom temperature of the distillation tower is the main indicator of the amount of evaporation of the material in that tower; a higher temperature corresponds to greater evaporation； Excessively high temperatures can even lead to entrainment, resulting in a higher dry point and darker color of the side-stream product. However, when the temperature at the bottom of the tower is low, the desired components cannot evaporate; this results in lower-quality product and increased load on the equipment below.
The bottom temperature of the distillation tower is the main indicator of the amount of evaporation of the material in that tower; a higher temperature corresponds to greater evaporation； Excessively high temperatures can even lead to entrainment, resulting in a higher dry point and darker color of the side-stream product. However, when the temperature at the bottom of the tower is low, the desired components cannot evaporate; this results in lower-quality product and increased load on the equipment below.
Ensuring the temperature at the bottom of the tower is critical in order to properly control the dry point of the product, at 95 degrees
The bottom temperature of the tower is the main indicator for measuring the amount of evaporation of the material within that tower. High temperatures result in high evaporation rates; excessively high temperatures can even lead to carrying over, causing the dry point of the side-product to increase and its color to darken. However, when the temperature at the bottom of the tower is low, the appropriate components cannot evaporate; as a result, the product quality is poor, which also affects the quality of the products from various side streams as well as the load on the equipment at the bottom of the tower.