THE A.A.B. COMPANY 615 McCallie Avenue Chattanooga, TN

Transcription

1 To: From: Re: Upper Management A.A.B. Project Engineers THE A.A.B. COMPANY 615 McCallie Avenue Chattanooga, TN Dryer Oven Maintenance & Energy Studies Date: November 26 th, 2013 The A.A.B. Company has recently acquired a drying oven for use in evaporative processes. The condition of the oven, however, is below operational standards. In order for this system to operate efficiently, there needs to be maintenance and an energy study performed. While performing these tasks, an Operational Manual was developed. The data acquisition system also needed to be calibrated. This was not able to be done due to inconsistent communication between the oven and the computer interface. The overall objectives were not able to be completed in the allotted time due to system malfunctions and un-foreseen setbacks. Enclosed: Drying Oven: Maintenance & Energy Studies Report

2 Drying Oven: Maintenance & Energy Studies Team AB: Alexandra Johnson Ann Palko Ben Kegley

3 Abstract The objective of the drying oven study was to use the Labview interface to measure and record the temperature and mass over time of the trays in order to first conduct an energy study and then to conduct a drying study. The drying study analyzes drying rates at a set temperature range. The experiments were put on hold due to a variety of electrical issues associated with getting the oven into operable condition. The oven is still in questionable condition due to the inoperability at high temperatures. Drying Oven Team AB i

4 Table of Contents I. Abstract... i II. Introduction...1 III. Theory...1 IV. Equipment...2 V. Procedure a. General Oven Operation b. Drying Experiment VI. Results and Discussion VII. Conclusions...20 VIII. Recommendations...21 IX. References...22 X. Appendices a. Oven Trouble Shooting b. LabVIEW Trouble Shooting Drying Oven Team AB ii

5 Introduction UTC has in its possession a drying oven manufactured by Blue M Electric Company in However, this drying oven has not been in operation for several years. Team AB was tasked with performing maintenance and energy studies. While accomplishing these tasks, an Operational Manual needed to be developed, the Data Acquisition System needed calibrating, and the power to the oven needed to be measured. While at UTC, the oven has been integrated to work with LabVIEW in order to become a remotely controlled system. LabVIEW is a graphical programming platform that helps engineers scale from design to test and from small to large systems. 1 LabVIEW is able to control the temperature setting as well as record the mass over time of trays that hang on strain gauges. The trays that hang on the inside of the oven can be filled with any substrate and then any solvent (the simplest being water) can be added in order to observe the drying rates due to various temperatures. There has been copper tubing added to the oven in order for water to be injected during heating, which can also be controlled by LabVIEW. A typical experiment in the oven would involve raising the oven to a steady temperature and injecting a sample of water into a tray and then observe and record the change in mass over time as the water evaporates. This is the simplest method of determining drying rates. Theory Drying is defined as a mass transfer process consisting of the removal of water (or another solvent) by evaporation. Drying rates are thus defined as the change in mass over time for the solvent. There are several variables that affect drying rates. Some of these variables being surface area of solvent, temperature, free or forced convection, velocity of forced convection, physical properties of the substrate and solvent, etc. One of the simplest ways to determine a drying rate is to plot the mass over time of a sample that is being heated. If there is a known amount of solvent at the beginning of heating, then the loss of mass represents the evaporation of the solvent. UTC has an oven that is set up to observe drying rates. The Blue M oven at UTC is a forced convection oven that has been integrated to be controlled with LabVIEW. The oven has strain gauges that are used to monitor mass along with copper tubing that allows water to be injected during experimentation. LabVIEW monitors the mass of the substrate that is suspended from the strain gauges along with the oven temperature and then plots these values over time. As water is injected onto the substrate, a change in mass can be observed. If the water is added after the oven has reached temperature, the water will heat up and begin to evaporate. As LabVIEW is plotting the mass, a decrease in mass will be observed due to drying. This plot can be used to determine the drying rate of water for the set temperature. Drying Oven Team AB 1

6 Equipment The equipment used is a drying oven manufactured by Blue M Electric Company in While at UTC, the oven has been integrated to work with LabVIEW in order to become a remotely controlled system. There has been copper tubing added to the oven in order for water to be injected during heating into the trays that hang on strain gauges. LabVIEW is able to control the temperature setting, record the mass over time of trays during heating, and actuate the valves that release water through the copper tubing. Figure 1: Blue M Drying Oven Figure 2: Inside the oven. Figure 3: Computer Station with LabVIEW. Drying Oven Team AB 2

7 Procedure General Oven Operation: 1. Make sure Drying-Oven.vi control panel is open on the desktop 2. To set the temperature of the oven use the Temperature Setting scale on the left hand side of the control panel by moving the slider or typing in a desired temperature Drying Oven Team AB 3

8 3. Adjust data recording intervals for the experiment 4. If you would like the charts on the control panel to be cleared before the experiment, assure button says YES Drying Oven Team AB 4

9 5. To collect your data, enter your address into the field on the right hand side of the control panel Then copy the URL in the box while the experiment is running and paste it into the internet search bar and press enter If a valid address has been entered, the data will be ed. Drying Oven Team AB 5

10 6. Assure that the Dryer Power button is pressed Off On 7. Click on the RUN button to start the experiment Drying Oven Team AB 6

11 8. Dryer will automatically shut off after 30 minutes, so be sure to watch the Countdown Clock and refresh when necessary by clicking Reset Countdown 9. While running: The fan in the oven should always be on while the oven is heating, if you do not hear the fan (it is very loud, you cannot mistake it) STOP the experiment and see the section on Troubleshooting To observe when the heater turns on or off, watch the light in the circuit box (Labeled #11) and listen for a loud click from the relay in the oven Watch the temperature plot on the control panel to assure the temperature is indeed rising Drying Oven Team AB 7

12 10. To end the experiment and turn the oven off, press the STOP button and assure the light in the circuit box (Label #0) is off Drying Oven Team AB 8

13 Drying Experiment: 1. Make sure a pan of sand is in the oven resting on a strain gauge and has a water inlet pointed down at it a. Pan Selection: Correct b. Pan Placement Incorrect Colored hanging arm for pan Matching color strain gauges to hang pans on c. Water Inlet Placement Marked copper tubing for water injection Black marks represent the Inlet valve # Make sure to take note of which strain gauge arm the pan is on and which water inlet is above it Drying Oven Team AB 9

14 2. Make sure Drying-Oven.vi control panel is open on the desktop 3. To set the temperature of the oven use the Temperature Setting scale on the left hand side of the control panel by moving the slider or typing in a desired temperature Drying Oven Team AB 10

15 4. Adjust data recording intervals for the experiment 5. If you would like the charts on the control panel to be cleared before the experiment, assure button says YES Drying Oven Team AB 11

16 6. If you would like to zero the weighing system, assure the Zero Weights button on the control panel is pressed before the experiment Drying Oven Team AB 12

17 7. To collect your data, enter your address into the field on the right hand side of the control panel Then copy the URL in the box while the experiment is running and paste it into the internet search bar after the experiment has ended and press enter If a valid address has been entered, the data will be ed. Drying Oven Team AB 13

18 8. Assure that the Dryer Power button is pressed Off On 9. Click on the RUN button to start the experiment Drying Oven Team AB 14

19 10. Dryer will automatically shut off after 30 minutes, so be sure to watch the Countdown Clock and refresh when necessary by clicking Reset Countdown 11. While running: The fan in the oven should always be on while the oven is heating, if you do not hear the fan (it is very loud, you cannot mistake it) STOP the experiment and see the section on Troubleshooting To observe when the heater turns on or off, watch the light in the circuit box (Labeled #11) and listen for a loud click from the relay in the oven Watch the temperature plot on the control panel to assure the temperature is indeed rising; if the temperature is not rising, see the section on Troubleshooting Drying Oven Team AB 15

20 12. After the system has reached a steady state temperature, water can be injected into the pan of interest by clicking on the appropriate water valve button 13. To end the experiment and turn the oven off, press the STOP button and assure the light in the circuit box (Label #0) is off Drying Oven Team AB 16

21 Results and Discussion One of the few experiments we were able to complete was a study of how much energy the oven used as it was heating up to set temperatures. This was simply done by setting the oven at a temperature (i.e. 150 F) and recording the times when the heater was on as well as off. Depicted below in Figure 4, is an example of one of these energy studies. The y-axis depicts the power to the oven in a percentage (either 0% or 100%), and the x-axis is the time (in minutes). This particular experiment was done starting at room temperature and heating up to 150 F. Figure 4: Time that oven is on after reaching steady state when at 150 F. We conducted two more of these studies at 200 F and 250 F respectively. Below in Figure 5, are the compiled results from the three experiments. This graph has the energy consumed by the oven in watts depicted on the y-axis, and the x-axis is the temperature in F. We were only able to collect data at three temperatures because the oven could not reach 300 F. Drying Oven Team AB 17

22 Figure 5: Energy usage versus temperature setting. This semester our senior team worked with two junior lab teams; Team Silver and Team Brown. The first experiment we had those teams run was to collect temperature profiles. This was done by heating the oven to a predetermined temperature and collecting the temperature readings from the computer interface. The experiment helped to familiarize the two teams with the oven and the LabView software. Originally, we were going to use this data to help us conduct an in depth energy study with a drying experiment, but due to all the complications with the oven this was not possible. Depicted below in Figure 6, is an example of the collected data from one of these experiments. 2 Drying Oven Team AB 18

23 Figure 6: Temperature profile over time of drying oven between 100 and 200 F. 2 The next experiment assigned to Team Silver and Team Brown was to measure the mass flow rates of the water as if flowed out of the copper tubing inside of the oven. Again, this was meant to help us with a drying experiment. Below in Figure 7, is an example of the flow rates found from each piece of tubing. 3 Drying Oven Team AB 19

24 Figure 7: Average flow rate of water inlet tubing. 3 Conclusions We were able to collect measurements for the oven energy study based on oven operating temperatures, although as noted in the report, these measurements were not completely accurate due to problems associated with the operation of the oven at higher temperatures. The potential data point at x=300 F was deemed at outlier and was therefore not included in Figure 5. The accuracy of the energy study is therefore in question since we only have 3 data points. According to Figure 5, the higher the temperature, the more energy is consumed. The graph shows a possible linear relationship with a formula to determine the energy consumed by the oven as a function of temperature. We had planned on doing a drying experiment with the Junior teams but had to spend the majority of our time fixing the oven. We were only able to partially complete the energy study that was supposed to help us derive the energy balances that we needed to properly do the drying experiment. Since the oven was first inoperable and then inconsistent at higher temperatures, were not able to conduct any drying experiments. Drying Oven Team AB 20

25 Recommendations Originally, we decided to try to get the oven in working order. This was done by fixing problems as we encountered them. As a whole, we probably spent more time, effort and money (labor costs) to fix the oven than it would have taken to buy a much newer oven (no more than 10 years old). Our recommendation would be to buy a newer oven to replace the old, unreliable oven. This would ensure accuracy in energy measurements and drying times and cost less money overall. If purchasing a newer oven is not feasible, hiring an electrical engineer would help get the current oven in working order in less time. To determine which to pursue, another energy study should be done that includes 5 temperature set points to determine a possible linear relationship, these should not be within 50 F of 300 F, which was the point at which the oven stopped working correctly. We recommend an energy study at the 5 different temperature set points of 150, 175, 200, 225, 250 F. If the oven is found to work correctly at these temperatures without any operating issues, an energy balanced can then be used and drying experiments can be potentially accurately pursued. Drying Oven Team AB 21

26 References [1] [2] Srofe, Raul. Drying Rate Lab. pg. viii Figure 3: Slope Transition from 100 F and 200 F. October 13, [3] Srofe, Raul. Drying Rate Lab. Pg. vii Figure 2: Mass Flow Rate of All Eight Spouts. October 13, Drying Oven Team AB 22

27 Appendix A Troubleshooting Oven: 1. Is the Oven Breaker set to ON? Dryer Oven Breaker Box Drying Oven Team AB 23

28 2. Did the fan stop working? a. Make sure the Dryer Power button is pressed on the control panel Off On b. Check to see if the breaker on the oven says ON and START button is pressed in Drying Oven Team AB 24

29 c. If the ON label is not sticking out of the switch, press the STOP-RESET button, and then the START button d. If (a) and (b) have been carried out but the fan will still not turn on, check to assure that the fan is receiving power. e. If problems still persists, contact Dr. Ennis or Dr. Henry Drying Oven Team AB 25

30 3. Is the oven not heating up? a. Make sure the Dryer Power button is pressed on the control panel Off On b. Check to assure the heater is receiving power. c. If problems still persists, contact Dr. Ennis or Dr. Henry Drying Oven Team AB 26

31 LabVIEW: 1. Is the LabVIEW control panel running? Running: Notice the different panel formats Not Running: Drying Oven Team AB 27

32 a. If LabVIEW is running, and oven is not working, see Oven Troubleshooting. b. If LabVIEW is not running, click the run button (looks like an arrow) and the control panel will start running again. c. If the user is unfamiliar with LabVIEW and there is any error message that pops up, record error type and go to step If oven is still not in operation, check to assure the program is operating properly by viewing the block diagram. If the user is unfamiliar with LabVIEW, go to step If problems still persists, contact Dr. Ennis or Dr. Henry (Jim- with error messages or issues that need to be fixed. Drying Oven Team AB 28