Answers to PERECON Exercise 1 (DLSU). This topic covered the introduction to Labor Economics.Full description
main points for behavioral economic from hurley notes from class chapter 1 and 2 and 3
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Compiler Design by Aho,Ulman,Lam and SethiFull description
exercise on correct usage
Exercise 3 to Be Solved
1/8/2014
Hand- i n Exer ci se 3: Answer s
Hand-in Exercise Exercise 3: Answers Flash Vessel Pressure, Liquid to Feed Ratio, Temperature In this example the first thing to think about is which flowrate is going to be used to regulate the ratio. It would seem sensible to use the feed rate for the ratio leaving the liquid rate for the level in the flash vessel. The other alternative would also work but not as directly. For the pressure loop the most direct action would be to put the valve on the vapour line thus leaving the heat input for the temperature which again is the most direct method. A diagram showing these loops is shown below.
Pressure, Temperature, Vapour Rate In this example the first loop to consider is the vapour flowrate. This is easily controlled using the vapour rate. Next consi consider der th the temperat temperatu ure. Ag Again ain it is is possi possible ble to use use the the heat heat in input. put. Finally think about what is left - pressure and inventory - with two streams left to regulate - the feed and liquid. The obvious choice, and in fact the only one that will work, is to use the feed for pressure and the liquid rate for the inventory. A diagram showing these loops is shown below.
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Hand-in Exercise 3: Answers
Pressure, Vapour Rate, liquid to feed ratio Again for this example control the vapour rate in the usual manner. Now think about the ratio. In this case one flowrate will regulate the ratio and the other one will regulate the inventory. Again it could be either way but the most direct is to have the feed rate on the ratio control and the liquid rate on the inventory. This leaves the heat input to determine the pressure. A diagram showing these loops is shown below.
Distillation Column Pressure, Distillate Rate, Bottoms Rate, Bottoms Composition In this example the first thing to consider is the distillate and bottoms rates. These can be controlled directly as shown in the diagram. The pressure of the column can be controlled in a number of different ways as discussed in the notes but for http://ecosse.org/jack/control/control4/5th/h3/handinans.html
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Hand-in Exercise 3: Answers
simplicity the direct condenser method is use in all these examples. The bottoms composition can be controlled using the boilup rate. This leaves the top inventory in the reflux drum controlled via the reflux rate and the bottoms inventory controlled via the feed rate. A diagram showing these loops is shown below.
Pressure, Feed, High Purity Distillate Composition, Bottoms Rate As before the first loops to place are the feed rate and the bottoms rate. Next add in the high purity distillate composition loop by controlling the quality via the distillate flowrate. The pressure loop is next which is completed in the same way as before. Finally add the inventory loops. The level in the reflux drum is controlled using the reflux flowrate and the inventory at the bottom of the column is via the reboil rate. A diagram showing these loops is shown below.
Pressure, Feed, Distillate to Bottoms ratio, Bottoms Composition First loop to place on the diagram is the feed rate. Then it is easy to add the pressure loop. Next consider the distillate to bottoms ratio. One method would be to use the bottoms flowrate to control the ratio. This would leave the distillate flowrate to regulate either the bottoms composition or the inventory at the bottom of the column. This would be very undesirable due to the time lag involved caused by the level on the plates. A much better solution would be to use the distillate flowrate for the ratio leaving the bottoms flowrate for the inventory at the bottom of the column and the reboil rate for the composition although again these two loop are interchangeable. The inventory at the top of the column is regulated via the reflux rate. A diagram showing these loops is shown below.
