EXPERIMENT MODULE CHEMICAL ENGINEERING EDUCATION LABORATORY PROCESS DYNAMIC OF DRAINED TANK (DPT)

Transcription

1 EXPERIMENT MODULE EDUCATION LABORATORY PROCESS DYNAMIC OF DRAINED TANK FACULTY OF INDUSTRIAL TECHNOLOGY INSTITUT TEKNOLOGI BANDUNG 2018

2 Contributors: Dr. Tri Partono Adhi, Dr. Winny Wulandari, Dr. Ardiyan Harimawan, Moch. Syahrir Isdiawan B., Raissa Alistia, Darien Theodric DPT

3 TABLE OF CONTENTS TABLE OF CONTENTS... i LIST OF FIGURES... ii LIST OF TABLES... iii CHAPTER I PREFACE... 1 CHAPTER II EXPERIMENT GOALS AND OBJECTIVES Experiment Goal Experiment Objectives... 2 CHAPTER III EXPERIMENTAL DESIGN Experimental Scheme Alat dan Bahan... 3 BAB IV WORKING PROCEDURE Calibration of Tank Cross-Sectional Area Determination of Input Flowrate Determination of Output Flowrate and Mathemical Model Parameters (k and n) Disturbance Simulation... 6 APPENDIX... 8 A. RAW DATA TABLE... 8 B. CALCULATION PROCEDURE DPT 2018 i

4 LIST OF FIGURES Figure 1. Equipment layout... 3 Figure 2. Flowchart of the calibration of tank cross-sectional area Figure 3. Experimental flow diagram of determining the input flowrate Figure 4. Experimental flow diagram for determining the output flow rate and the mathematical model parameters k and n Figure 5. Experimental flow diagram of disturbance simulation Figure 6. Correlation between water volume and water level Figure 7. Correlation between volume change and time span Figure 8. Correlation between ln(-dh/dt) and ln h DPT 2018 ii

5 LIST OF TABLES Table 1. Experimental data of correlation between volume and water level Table 2. Correlation between water level and time Table 3. Calculation result of volume change Table 4. Calculation result of flowrate Table 5. Correlation between water level and time Table 6. Calculation result of linearization method Table 7. Calculation result of k and n using linearization method Table 8. Calculation of the difference between h from integration and h from experimental data Table 9. Calculation result of k and n using integration method DPT 2018 iii

6 CHAPTER I PREFACE Chemical plant is a series of various processing units that are systematically and rationally integrated. The overall operation goal of the plant is to convert raw materials into more valuable products. In the operation, the plant will always experience disturbance from external environment. During operation, the plant should always consider the technical, economic, and social aspects to reduce the significance of external change influence. Process dynamics shows the performance of processes whose profiles are always changing over time, happening as long as the process system has not reached steady state. Dynamic state occurs when disturbance is introduced to a steady-state condition. For the process to be stable, the dynamic characteristics of the process system and the processing system must be identified. Understanding of the dynamics of apparatus and operating equipment will ease the control, prevention of damage, and monitoring where there is damage to the condition of the equipment such as decrease of equipment performance or inability of equipment to work within the operating specifications. Learning about process dynamics is also important to predict the behavior of the process under certain conditions. Forecasting the process behavior needs to be done in the design of process control to: Supress influences from disturbances. Ensure process stability. Optimize the process system performace. Keep the security and safety of work environment. Fulfil the desired product specification. Keep the operation economical. Fulfil the environmental requirement. DPT

7 CHAPTER II EXPERIMENT GOALS AND OBJECTIVES 2.1 Experiment Goal By conducting this practicum, students are expected to learn unsteady state process dynamics (behaviour) through simple physical system. 2.2 Experiment Objectives The objectives that students are expected to fulfil are: 1. Recognize and define steady state and unsteady state condition of simple physical system. 2. Build mathematical model of simple physical system in unsteady state condition. 3. Determine parameters in built mathematical model from experimental data. DPT

8 CHAPTER III EXPERIMENTAL DESIGN 3.1 Experimental Scheme The equipment layout for process dynamics experiment of empyting tanks is shown by Figure 3.1. Reservoir Q1 Reservoir Q2 (valve for disturbance) Tank 1 k1, n1 Q3 Tank 2 k2, n2 Q4 Water reservoir Figure 1. Equipment layout. 3.2 Alat dan Bahan Equipments used in the experiment are: A set of process dynamics experimental equipment of emptying tank. Stopwatch Beaker glass Measuring cup Bucket Cloth Substance used in the experiment is: Water DPT

9 BAB IV WORKING PROCEDURE 4.1 Calibration of Tank Cross-Sectional Area First, tank 1 is emptied and then filled with known water volume measured by measuring cup. The height of water surface after every addition of known water volume is noted. The experiment is done six times. After the data are obtained, the correlation between water volume and water surface height is plotted. This procedure is then done to tank 2 as well. The flowchart of the calibration of tank cross-sectional area is shown by Figure 4.1. Start Water with known volume is filled into the tank No The height of water surface is noted Six different known water volume End Yes Figure 2. Flowchart of the calibration of tank cross-sectional area. 4.2 Determination of Input Flowrate To determine the input flow rate, first the tank is emptied, the output valve is closed, and the input valve is opened with a certain opening. The time when the water surface reaches certain height is noted. The height of water in the tank is correlated with the volume of water by DPT

10 multiplying the height of the water and the cross-sectional area of the tank. Correlation between the volume of water and time is plotted. The gradient of this curve expresses the input volumetric flowrate. The procedure is then repeated on different valve openings. The experimental flow diagram for determining the input flow rate can be seen in Figure 4.2. Start Tank is emptied, out valve is closed, input valve is opened Amount of time for addition of certain water level is noted Four variation of input valve openings End Yes Figure 3. Experimental flow diagram of determining the input flowrate. 4.3 Determination of Output Flowrate and Mathemical Model Parameters (k and n) The tank is initially filled to full, then the valve output is opened with a certain opening and time is recorded for each drop of a certain water level. The volume of water in the tank is correlated with the height of the water in the tank by multiplying the water level and the cross-sectional area of the tank. The correlation between the volume of water and time is plotted. The gradient of this curve expresses the volumetric output flow rate. The parameters k and n are obtained from the processing of experimental data. The procedure is then repeated on different valve openings. This procedure is performed on tank 1 and 2. The experimental flow diagram for determining the output flow rate and the mathematical model parameters k and n can be seen in Figure 4.3. DPT

11 Start Tank is filled with water Output valve is opened by certain opening Amount of time for certain water level drop is noted Four variation of output valve openings End Yes Figure 4. Experimental flow diagram for determining the output flow rate and the mathematical model parameters k and n. 4.4 Disturbance Simulation An experimental simulation of disturbance is performed on tank 1 because this experiment must be carried out with one of the flow rates being kept constant. Tank 1 is first emptied, and then all valves are closed. After that, the input valve (Q1) and the output valve (Q3) are opened simultaneously with specified opening. The water level for a certain amount of time span is then recorded. Recording is done until the steady state is reached, that is when the water level in the tank does not change anymore. After reaching steady state, this condition is then disturbed. The disturbance may be the addition or reduction of input/output valve openings, otherwise the disturbance may also be the increase of the input stream by opening disturbance valve (Q2). After being disturbed, the water level for a certain amount of time span is then recorded and stopped after the system reaches steady state. The experimental flow diagram of disturbance simulation can be seen in Figure 4.4. DPT

12 Start Tank is emptied Output and input valve are opened simultaneously with certain opening Water level after certain amount of time is noted until steady state is reached Disturbance is introduced to the steady system Water level after certain amount of time is noted until steady state is reached again End Figure 5. Experimental flow diagram of disturbance simulation. DPT

13 APPENDIX A. RAW DATA TABLE 1. Tank Cross-Sectional Area Calculation Tank 1 Tank 2 No Volume (ml) h (cm) No Volume (ml) h (cm) Input Flowrate Calculation...% opening...% opening...% opening...% opening No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) DPT

14 ...% opening...% opening...% opening...% opening No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) Output Flowrate Calculation 100% opening 75% opening 50% opening 25% opening No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) DPT

15 4. k and n Parameter Calculation 100% opening 75% opening 50% opening 25% opening No h (cm) t (s) t (s) t (s) t (s) DPT

16 5. Disturbance Simulation Before disturbance is introduced % of input opening 1 = % of input opening 2 = % of output opening = No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) DPT

17 After disturbance is introduced % of input opening 1 = % of input opening 2 = % of output opening = No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) DPT

18 B. CALCULATION PROCEDURE 1. Tank Cross-Sectional Area Calculation a. Calculating from water volume and level For example, the data obtained from experiment are shown in Table 1. Table 1. Experimental data of correlation between volume and water level. Tank 1 No Volume (ml) h (cm) The volume can be calculated by using the following formula: Dengan: V = water volume (ml) A = tank cross-sectional area (cm 2 ) h = water level in tank (cm) Therefore, tank cross-sectional area can be known from the gradient of volume and water level correlation. The curve of the correlation between volume and water level from Table 1 is shown in Figure B.1. DPT

19 V (ml) y = x R² = h (cm) Figure 6. Correlation between water volume and water level. Note: The curve should have (0,0) intercept From Figure B.1, the tank cross-sectional area is the same as the curve gradient, which is cm 2. b. Calculation from tank circumference From the tank circumference, the tank diameter can be found by using the following formula: with: D = tank inside diameter (cm) K = tank inside circumference (cm) Tank cross-sectional area can be calculated by using the following formula: Dengan: A = tank cross-sectional area (cm 2 ) D = tank inside circumference (cm) 2. Calculation of input and output flowrate Say that from the experiment we obtained data which are shown in Table B.2. DPT

20 Table 2. Correlation between water level and time. 100% opening 75% opening 50% opening No h (cm) t (s) No h (cm) t (s) No h (cm) t (s) The volume change must be calculated first by using following formula: with: V = volume change (ml) A = tank cross-sectional area (cm 2 ) h = water level change (cm) The result of volume change is shown by Table B.3. DPT

21 Table 3. Calculation result of volume change. 100% output opening 75% output opening 50% output opening No h (cm) t (s) V (cm3) No h (cm) t (s) V (cm3) No h (cm) t (s) V (cm3) The volume change can then be calculated using the following formula: with: V Q t = volume change (ml) = flowrate (ml/s) = time span (s) Therefore, the flowrate can be known from the curve gradient of correlation between volume change and time span. The plot is shown in Figure B.2. DPT

22 y = x R² = y = x R² = V (ml) y = x R² = t (s) 100% bukaan 75% bukaan 50% bukaan Figure 7. Correlation between volume change and time span. From Figure 7., the flowrate of every opening is shown by Table 4. Table 4. Calculation result of flowrate. Opening Flowrate (ml/s) 100% 256,96 75% 245,01 50% 159,61 3. Calculaton of k and n Parameter Say that the data we obtained are shown in Table5. Table 5. Correlation between water level and time. h (cm) 100% opening 75% opening 50% opening 25% opening t (s) t (s) t (s) t (s) DPT

23 h (cm) 100% opening 75% opening 50% opening 25% opening t (s) t (s) t (s) t (s) a. Calculation with Linearization Method Correlation between water level rate of change and water level is shown by following formula: Dengan: h = water level (cm) t = time (s) k = parameter n = parameter The correlation that is shown by above formula can be linearized into: DPT

24 From the linearization, the plot between ln(-dh/dt) and ln h will give a result of a gradient. The value of the gradient, which is n and cross point, can be used to calculate k value. The result of calculation using linearization method is shown by Table 6. h (cm) ln h Table 6. Calculation result of linearization method. 100% opening 75% opening 50% opening 25% opening t (s) ln(-dh/dt) t (s) ln(-dh/dt) t (s) ln(-dh/dt) t (s) ln(-dh/dt) From Table B.6., the plot between ln (-dh/dt) and ln h is given by Figure 8. DPT

25 ln(-dh/dt) y = x R² = y = x R² = y = 0.1x R² = y = x R² = ln h 100% bukaan 75% bukaan 50% bukaan 25% bukaan Figure 8. Correlation between ln(-dh/dt) and ln h. The calculation result of k and n is shown by Table 7. Table 7. Calculation result of k and n using linearization method. Output Valve Opening Percentage k n 100% 199,27 0,12 75% 203,28 0,08 50% 135,88 0,11 25% 43,04 0,14 b. Calculation with Integration Method From the formula of correlation between level change and water level, the level at certain time can be found by integration method. DPT

26 From above formulas, k and n can be predicted so that the difference between h from integration and h from experimental data is minimum. The integration method is done by using the Solver application in Microsoft Excel. The calculation of the difference between h from integration and h from experimental data is shown in Table 8. Table 8. Calculation of the difference between h from integration and h from experimental data. 100% opening 75% opening 50% opening 25% opening k = k = k = k = h (cm) n = 0.3 n = 0.28 n = 0.27 n = 0.36 t (s) h integral h t (s) h integral h t (s) h integral h t (s) h integral h Total = 1.60 Total = 1.69 Total = 1.18 Total = 1.16 DPT

27 The result of k and n calculation using integration method is shown by Table 9. Table 9. Calculation result of k and n using integration method. Output Valve Opening k n Σ h (cm) 100% % % % DPT

28 JOB SAFETY ANALYSIS No Substance Sifat Bahan Treatment Action 1 Water No special treatment needed. (H 2 O) Melting point 0 o C (1atm). Boiling point 100 o C (1 atm). Stable on reaction. Viscosity = cp at 26 o C. Good solvent Thermal conductivity = 0.61 W/m.K (26 o C) Accidents that may happen Short circuit connection happening due to electric connection with water Falling down the stairs when conducting experiment Slipping due to water puddle from hose leakage Working Safety Equipment Countermeasures Try to cut the electrical connection of equpment. If this is not possible, contact authorities. Give adequate medical treatment to the wound. Make sure all hose connections are coupled well to prevent water leakage which results to water puddle. Clean if there s water puddle. Lab Coat Goggle Rubber boat Working Safety Procedure Experimental Phase Working Safety Procedure Equipment Make sure all connection are connected well, especially blowdown hose. Checking Make sure the electrical connection of pump is connected well. Experiment Be cautious in climbing the equipment stairs, try climbing with dry shoes. Post- Cut electrical connections of all equipment that requires electricity to operate. Experiment Assistant Advisor Lab TK Coordinator DPT