As the vapor moves up the column it gets progressively cooler which allows some of the mixture to condense and further concentrates the vapor with the lightest component s.
The number of steps corresponds to the number of trays needed for a given mixture. Determining the size of the tower and the number of trays needed was historically a very difficult process involving many calculations.
The McCabe-Thiele method greatly simplified that process. The method uses a graphical representation of the material balance equations as operating lines on a graph of the liquid composition x-axis and the vapor composition y-axis. The bottom line in Figure 3 is the x-y line. This starts at the origin and ends where x and y both equal 1.
This line would represent a distillation column that operated at total reflux and total boil- up, meaning that all of the vapor and all of the liquid is recycled back into the system. The next line added is the vapor —liquid equilibrium line for a binary system which is found experimentally. By moving step-wise between the two lines we can find the number of theoretical plates needed for a specific separation of a binary mixture and the liquid and vapor composition at any point in the distillation column.
These stage lines can be seen in Figure 3. In practice, we want to draw a purified product out of the column in the form of either a distillate top of the column or the bottoms product bottom of the column or both. This means that we cannot use the x-y line for such a column. Subsequently, as we remove more distillate as product we decrease the slope of the top operating line, which is the line for the reflux ratio.
By changing the amount of liquid re-boiled, which is liquid returned to the column as a vapor, or by changing the amount of vapor refluxed, returned to the column as a liquid, we change the number of theoretical plates necessary for a given separation. We can see from the diagram in Figure 4 that where that line intersects with the two operating lines is the feed stage, or the tray at where the incoming stream enters.
When dealing with multi- component mixtures addition assumptions and calculations are necessary. There are a number of issues that need to be watched when sizing a continuous distillation column properly. They are: Foaming- foaming occurs when the gas passing upward causing the liquid to bubble excessively. While this normally depends on the properties of the liquid, it can also be caused by improper tray designs.
Entrainment- Occurs when the vapor velocity is too high due to a column having too small of a diameter. This causes liquid to be held up at the trays and does not allow proper circulation of the liquid. Weeping- Occurs when the vapor velocity is too low. When the velocity drops too low, liquid starts to fall, or weep, through the holes in the plates. This does not allow enough liquid to get to the re-boiler which means that the entire column needs to be shut down and re-started.
Flooding- This occurs when liquid entrainment become too severe. This causes a large pressure drop in the column and contaminates the distillate. The column is constructed of a round bottom flask 7 which holds a methanol- water solution. This solution is distilled by applying electrical energy to the heating jacket 24 which heats up the solution causing the volatile liquids and gases to rise.
Total reflux occurs in the system by feeding cooling water 10 into a cooling coil 16 at the top of the column. Thermocouples T1-T9 measure the temperatures at various points in the system and output them onto an electrical temperature monitor Only open when filling round bottom Check for leaks and cracks that 5 Feed Supply Valve Nalgene flask could cause malfunctions.
Valve is labeled to either drain, fill or Check for leaks and cracks that 6 Three way valve Swagelok prevent loss could cause malfunctions.
Do not heat when empty!! Ensure flask is cooled before Used to hold the Methanol-water 7 Round Bottom Flask Na adding any fluid Look for any solution leaks or cracks before adding solution or heat.
The top piece Examine entire column for any 9 Glass sections of column Na contains the cooling water tubes and leaks, cracks or anything that a narrowed opening so that total could fracture structural integrity reflux can be assumed. Always open when distillation Cooling water Connection 10 ChE Unit Ops Cooling water is supplied by lab column is in operation to supply for Apparatus. Always open when distillation Cold Chicago Used to start flow of cooling water 11 Cooling Water Supply Valve column is in operation to supply Faucets into system.
Check for leaks and cracks. Coil where heat transfer takes place Check for any leaks or cracks that 16 Cooling Coil Na between distillate and cooling water could cause malfunctions. Measures temperature of cooling Check for any leaks or cracks that 17 Temperature Gauge Weksler water exiting column in degrees could cause malfunctions.
Heat Supply for Heating Conducts electricity and passes it into Examine for loose wires or 20 Powerstat Jacket the heating jacket malfunction Check for loose wires or Displays temperature taken at the 21 Digital Temperature Monitor Monogram malfunctions that may be different thermocouples. Make sure probes are secure and 22 Thermocouples Omega Reading outputs on Digital allow no leaks to touch them.
Monitor temperatures Switch either on or off. Heats the bottom of the distillation Very HOT. Exercise extreme 24 Electric Heating Jacket Na column electrically. Pay close attention to Measures the temperature above stage T8 Thermocouple above Stage 6 Omega temperature so column does not 6.
Measures the temperature of the Pay close attention to Thermocouple placed before T9 Omega cooling water before it is introduced temperature so column does not cooling coil into the cooling coil. Close when no Gas Sample Collection Port G1 Na plate via a sealed tube and release valve Keep samples cold by collecting sam for stage 1. You will also benefit by visiting the video from the previous distillation experiment that was completed last semester, as that one has a more detailed description of the valves and sensors: Term 1 Experiment Video.
This distillation process will be run on continuous basis using the dosing pump. The mixture of ethanol and water will be fed onto the first lowest level in the column by opening valve V4. With continuous feed students will be collecting and analyzing the distillate and residue on continuous basis.
Distillate will be captured in the graduated glass receiver Component 11 in Figure 2 and the residue will be collected in another graduated glass receiver component 14 in Figure 2.
Valves V12 and V15 will have to be opened, to drain the distillate and residue from the graduated cylinders into the storage tanks if the liquid levels in the cylinders will be reaching maximum volume. Two runs will be completed with different reflux ratios, one with the value of 1. All Rights Reserved. Skip to content Introduction Distillation is a form of physical separation. Equipment In the distillation column in the E laboratory, the trays contain a bubble-cap.
Looks amazing! Exactly what a newbie like me needs to see. Glad the weekend is coming up, I've got some reading to do! We in the SD core have encouraged the development of this document and finally have something to show - all thanks to Crozdog - take a bow please. Stand up! OK, Enough already! Crozdog is also working on a manual for operating a SD Gin Basket so if you can contribute to his efforts on that it would also be appreciated.
He has a beta SD setup of Gin Basket prototypes and is trying to concoct and navigate through the myriad ways of using the Gin Basket. The possibilities are far reaching, not just for flavoring alcohol into gin but also for cooking, extracting essence and even perfumes. I think the development of the Dash manual and the Gin Basket manual to be a key for distillers to fully utilize their equipment. At a minimum they have proven guidelines to follow.
General release of the Gin Basket is expected to be in about a month from now. I said that last month? Trust me, either in a month or the next. And that's a fact. To determine the appropriate tray, it will consider the fouling tendency, allowable of pressure drop and turndown requirement in the column.
Heating element installed at the bottom of to ensure the liquid mixture evaporates in the whole column. The vapor phase will rise up into the condenser and the product will be entering into the distillate tank, meanwhile the liquid will go downward as a waste or bottom products. There are two heat exchangers above the distillation column. Then the reflux tank will be filled with the condensate that flow from condenser.
The electromagnetic controlled in the column by switching of on and off controlled the reflux ratio. The remaining from the reflux tank then turned back to the top of the column. Therefore, the refractive index of every sample analysed by refractor meter.
The rectification is the mass transfer between the two phases in equilibrium. Figure 2 - Process Flow Diagram for Common Distillation Column Process From the distillation column system, there are two principle method that need to be followed in order to carry out the experiment which is batch distillation method and continuous steady state distillation process.
Batch distillation process is the process when there is no reflux and the vapor that boiling the liquid mixture to be separated and condensing vapor not allowing any liquid to return into the top column. Therefore, the continuous distillation process is vice versa. Some example of continuous distillation is flash distillation single stage partial vaporization and rectification distillation.
In the industries, there are many categories of products that use distillation for separation such as petroleum refining, petrochemical, process of natural gas and beverage. In generally, the typical aim to remove the light component from mixture of heavy component.
Other example of distillation process is within the food industries which concentrating essential oils and flavour, deodorization of fats and oil. Distillation is a physical process used to separate chemicals from a mixture depending on the differences in volatilities of the components that make up the mixture.
In the distillation process, a volatile vapor phase and a liquid phase that vaporizes are involved Geankoplis, Their operation is based on the difference in boiling temperatures of the liquid mixture components. The binary mixture of methylcyclohexane-toluene is used in the experiment to understand the concept of distillation. The vapor raised in the boiler flow into the unit at the bottom of the column. The velocity of the vapor passing through the column depends on the boil-up rate. As the vapor passes straight upward through the liquid on the sieve trays Tham M.
The pressure drop is expected to increase as the boil — up rate is increases. As the vapor exits the top of the unit, it is cooled by a condenser Tham M. The condensate is stored in the reflux drum.
The refractive indexes can be measured for mixtures of known concentration made up for the binary system. The refractometer works using the principle of light refraction through liquids ProSciTech, It measure the critical angle of the liquid or mixture under test and different concentration will yield to different reading of the critical angle.
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