【Daily Question】Chemical Engineering Principles 187: Distillation Operations (September 29)
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The last edit to this post was made by Zaihui Kangqiao on 2015-10-9 at 07:56. The Chemical Engineering Theory section is now launching a \"One Question per Day\" activity aimed at helping everyone reinforce their basic knowledge in chemical engineering. Subsequent series will include those on \"Principles of Chemical Engineering\", \"Mass Transfer and Separation\", \"Thermodynamics in Chemical Engineering\", and \"Chemical Process Engineering\". We hope for your active support! Answers to the questions in the \"One Question per Day\" activity can be viewed directly, and the thread will be closed after 1 day ! You get 3 wealth rewards just for participating, and an additional 3 wealth points for correct answers~ Short answer question: Why are reflux and reboilers necessary in the distillation process? Reflux is a necessary condition to ensure the normal and stable operation of a distillation column. It is to replenish the liquid phase composition and quantity on the tray ； Maintain the stability of the liquid phase composition and quantity on the tray ； Increase the concentration of the overhead product. The reboiler mainly provides a certain amount of rising steam.
Reflux is used to concentrate the light key components at the top of the tower, while reboiling is used to concentrate the heavy key components at the bottom of the tower.
It achieves the effect of mass and heat transfer of the materials, as well as multiple partial vaporizations and partial condensations of the components, in order to achieve component purification
Why are reflux and reboilers needed in the distillation process? Answer: High-purity separation of liquid mixtures is achieved through reflux, and the purity of the product can be controlled by adjusting the reflux ratio ； A reboiler can vaporize the liquid once again; the returning solvent, after multiple mass transfer processes, is recombined and sent to the bottom of the tower, where it needs to be boiled again for distillation to continue.
1. Ensure the presence of both gas and liquid phases for mass transfer within the distillation tower； 2. Ensure that the product meets the distillation requirements
The main indicators for evaluating distillation operations are: ① Product purity. ②Component recovery rate. ③Total operation cost. The number of plates in a plate tower or the height of the packing layer in a packed tower, as well as the location where the feed liquid is introduced and the reflux ratio, all have an impact on the purity of the product. Adjusting the reflux ratio is the main method used in distillation column operation to control product purity.
: ① Product purity. Factors such as the number of trays in a plate column or the height of the packing layer in a packed column, as well as the location where the feed liquid is introduced and the reflux ratio, all have an impact on product purity. Adjusting the reflux ratio is the main method used in distillation operations to control product purity. ② Component recovery rate. This is the ratio of the concentration of a component in the product to its concentration in the feed liquid. ③ Total operating cost. This includes the heating costs associated with the reboiler, the cooling costs related to the condenser, and the depreciation cost of the distillation equipment. Changing the reflux ratio during operation directly affects these first two costs. Additionally, even with the same amount of heat input and cooling, the heating and cooling costs vary depending on the boiling and condensing temperatures; especially when steam is not used as a heating agent or when air or cooling water cannot be used as coolants, these costs increase. Choosing an appropriate operating pressure can sometimes avoid the need for high-temperature heating agents or low-temperature coolants (or refrigerants), but it increases the costs associated with pressurization or vacuum creation
Why are reflux and reboilers needed in the distillation process? Answer: It is a distillation method that uses reflux to achieve high-purity separation of liquid mixtures; without reflux, it is simply distillation rather than rectification. A reboiler, as the name implies, is used to vaporize the liquid again. The solvent that has undergone reflux undergoes multiple mass transfer processes before being sent back to the bottom of the tower, where it needs to be boiled once more for rectification to continue.
Why are reflux and reboilers needed in the distillation process? Answer: Reflux is a necessary condition to ensure the normal and stable operation of a distillation column. It is to replenish the liquid phase composition and quantity on the tray ； Maintain the stability of the liquid phase composition and quantity on the tray ； Increase the concentration of the overhead product. The reboiler mainly provides a certain amount of rising steam.
This post was last edited by charlie_999 on 2015-9-29 09:53. Short answer: Why are reflux and reboilers necessary in the distillation process? Answer: Reflux is a necessary condition to ensure the normal and stable operation of a distillation column. It is to replenish the liquid phase composition and quantity on the tray, thereby ensuring effective heat balance ； Facilitates adjustment of process parameters. Maintain the stability of the liquid phase composition and quantity on the tray ； Increase the concentration of the overhead product. The reboiler mainly provides a certain amount of rising steam.
It is a distillation method that uses reflux to achieve high-purity separation of liquid mixtures; without reflux, it is simply distillation rather than rectification. A reboiler, as the name implies, is used to vaporize the liquid once again. The solvent that has undergone reflux undergoes multiple mass transfer processes before being sent back to the bottom of the tower, where it needs to boil again for rectification to continue.