GENERAL SIR JOHN KOTELAWALA DEFENSE UNIVERSITY DEPARTMENT OF MECHANICAL ENGINEERING MECHANICS & CONTROL LABORATORY Liquid Solvent Distribution with Pressure Control INSTRUCTOR MS. MONIESHA THILAKARATHNA NAME U PASCALINE INDEX NO F/ENG/21/6275/MC INTAKE 38 STREAM MECHACTRONICS GROUP NO GROUP MEMBERS MC01 MDD PERERA SWHS MENDIS T STEVEN DATE OF 18/04/2023 PERFORMANCE DATE SUBMISSION OF 02/05/2023 INTRODUCTION PLCs are specialized computers used to automate industrial operations, made up of a CPU, I/O modules, and programming software. They are versatile and can be programmed to carry out tasks such as monitoring inputs, processing data, and controlling outputs. In this practical, a PLC was used to control a liquid distribution system by monitoring liquid pressure. Programming software is used to create the code that instructs the PLC on how to carry out its functions. PLCs are an essential tool in modern industry, able to automate a wide range of tasks and provide real-time control and monitoring of industrial processes. Figure 1 : Programmable logic controller (PLC) The pressure control system is set to start when a switch is switched on and stop when that same switch is switched off. When the switch is switched on, the pump starts filling the water tank with cleaning solution until the pressure reaches 0.6 Bar, when the pump is shut off and the valve is opened to discharge the liquid to clean the solar panel. The valve stays open until the pressure reaches 0.2 Bar, at which point, the valve is closed and the pump restarted. Because the system is designed to clean sets of three solar panels, each time the valve is opened, a counter is increased, and when it hits 3, the system is allowed 10 seconds to rest before resetting the counter and going on to the next set of solar panels. Figure 2:Diagram Of Control system This is a closed loop control system which contains a digital input for the start/stop instruction (the switch), a pressure sensing transducer (PS), and a pump (P), and valve (V) as the actuators, all controlled by a PLC. Figure 1b.Control system of liquid solvent distribution with pressure control OBJECTIVES - To comprehend the operation of a liquid solvent distribution system with two pressure levels. - To create a flowchart for a two-level pressure control system for a liquid solvent distribution system. - To put the application's true capabilities to the test. PRE-LAB QUESTIONS APPARATUS Figure 3: Diagram of basic components of level control system Fluid Tank(WT): A storage tank to hold the desired amount of water Pressure Transducer: An electronic pressure measurement system. It converts a physical pressure value into an analogue electrical signal by accurately measuring the deflection of a pressure. Pump driver: it is operated using a PWM signal PROCEDURE Calibrating the Pressure Sensor - The water storage tank (SD in Figure 1) was already filled. - The 0 cm mark of the mobile scale was aligned with the 4 cm mark of the permanent scale on the WT. - The following settings were made to the DL 2314 Process Panel interface: 1. The delivery and motor valves were turned completely counter-clockwise to the fully open position. 2. The On-Off Driver Interfaces were connected, and the solenoid valve switch was set to the OFF position. 3. The manual valve was turned completely counter-clockwise to the fully open position. 4. The drain and needle valves were turned completely clockwise to the fully closed position. 5. The air valve was turned completely clockwise to the fully closed position. 6. The knob on the PID interface was turned completely counter-clockwise to give 0V. - It was ensured that all of the switches on the DL 2314 Control Panel were turned off and that all potentiometers were set to 0. - The Control Panel was configured as follows: 1. The pressure sensor's terminals 9, 10, 11, and 12 were connected to the P/U interface's corresponding terminals. 2. Linear driver terminals 18, 19, and 20 were connected to set point 1's corresponding terminals. 3. The positive terminal of the digital multimeter (configured to measure digital voltage) was connected to pressure interface terminal 13 and the negative terminal to the earth terminal. - The hardware devices of the DL 2314 Control Panel were switched on by switching on both the power and mains switches. The 15V and +15V Lights in the controllers' PID areas lighted up. - By moving the knob on set point one clockwise, the WT was filled with water up to the 0cm mark on the mobile scale. (The air valve was kept open while filling the tank, and closed afterwards.) - The trimmer offset was adjusted until the multimeter read 0V. - The terminal of set point 1 was connected to terminal 18 of the linear driver. - The knob on set point one was turned clockwise to set the voltage at 10V; the motor pump started to operate. - When the pressure gauge read 1 bar, the set point 1 knob was turned counter-clockwise to stop the pump. - The trimmer gain was adjusted such that the multimeter read 10V. - The pressure sensor was now calibrated. - The mains switch was switched off to switch off the hardware devices of the DL 2314 Control Panel. TESTING AND RESULTS Testing 1. After a program was loaded and was running in the PLC, the actual status of the ladder elements was monitored using the step 7 software. 2. The voltmeter was connected in parallel to the power supply of the pump. 3. Voltage was set to 10V by turning the “set point 1” knob until the digital multimeter displayed 10v. 4. The wires were connected to the input 0.0 to start the process automation. Figure 5: Diagram of CPU 1214C 5. On/off of the monitoring was pressed from the TIA portal to observe the status of the developed Program. a) Before wires were connected to the digital input I0.0, the status of the input was set to OFF b.The PLC kept the pressure between the two values (0.2 Bar and 0.6 Bar). c. After 3 events the counter was switched ON d. A delay of 10 secs was added to allow the other set of solar panels to be cleaned. 6. The closed fluid tank was found to have an air leak during the experiment, which caused the pressure to steadily drop. This could have caused a calibration error because there will be a drop in pressure when we put the pressure inside the closed fluid tank at 1 Bar and adjust the trimmer gain to 10V in that brief period. Even though the valve should be closed and the pump should turn on again at 0.2 Bars, it actually occurs at 0.15 Bars. Figure 6: Diagram of pressure gauge Even though the PLC system is intended to release the valve and turn off the pump at 0.6 Bars in that situation, it will happen at 0.55 Bars. DISCUSSION 1. List the sequence of process steps (Flow chart) and prepare the inputs/output table Flow Chart of Liquid Solvent Distribution System With Pressure Level Control OFF ON YES NO YES NO NO YES YES NO 2. Briefly explain the pressure sensor calibration procedure The pressure in the closed fluid vessel was initially 0 bars, and the voltmeter measurement was set to 0V. The pump was then manually switched on until it reached 1 bar of internal pressure, and the voltmeter measurement was adjusted to 10V using the trimmer gain. When calibrated, the pressure gauge displayed a voltage variation of 0-10 volts when the pressure increased from 0 to 1 bar, indicating a constant gradient increment. 3. Why are signal conditioning circuits important in automated control systems? Signal conditioning circuits are essential in automatic control systems because they oversee processing, amplifying, filtering, and converting the incoming signals from various sensors and transducers into a form that can be precisely measured, analyzed, and used by the control system. Without appropriate signal conditioning, the signals may be too weak, noisy, distorted, or incompatible with the needs of the control system, leading to incorrect or unreliable control actions. By increasing the signal-to-noise ratio, lowering errors, compensating for non-linearities, and adapting to changing circumstances, signal conditioning circuits play a crucial part in improving the accuracy, dependability, and efficiency of the control system. Additionally, they can shield the control system from harm or dysfunction caused by too many or incorrect impulses. 4. What would happen if temperature changes in the system? The precision and stability of pressure sensors and control valves can be impacted by temperature changes in a pressure control system, which can result in subpar performance and possible safety risks. Changes in temperature can cause the materials in the system to expand or contract, which can alter pressure measurements and control actions. Furthermore, high temperatures can cause the pressure sensors and valves to drift or malfunction, resulting in incorrect pressure control and the possibility for equipment harm or failure. 5. Applications of pressure control systems in industry. In many different sectors, including the chemical, oil and gas, pharmaceutical, food and beverage, and many others, pressure control systems are used extensively. Pressure control devices are frequently used in the following industrial contexts: ● Pharmaceutical manufacturing: Uses pressure control systems in a number of procedures, including fermentation, purification, and formulation, to keep sterile conditions, avoid contamination, and guarantee product quality. ● Chemical processing: In reactors, distillation columns, and other vessels, exact pressure levels are maintained by pressure control systems to regulate reaction rates, product quality, and safety. ● Production of oil and gas: To keep safe and effective pressure levels, avoid blowouts and wellbore damage, and maximize production rates, pressure control systems are used during drilling, well testing, and production operations. ● Heating, ventilation, and air conditioning systems (HVAC): Pressure control systems are used to manage air pressure and flow rates for optimum comfort and energy efficiency. ● Food and beverage processing: Pressure control systems are used to keep the required pressure levels for cooking, sterilization, filling, and sealing processes. . CONCLUSION A pressure control system is an essential part of many industrial processes and applications because it enables exact regulation and maintenance of pressure levels. It uses a variety of sensors, valves, and controllers to monitor and change the pressure in real-time, ensuring safe and effective operation and avoiding damage or issues with product quality. However, there are some drawbacks to pressure control systems, such as the difficulty and expense of installation, upkeep, and repair, as well as the possibility of system failure due to faulty sensors, valves, or user error. The advantages of pressure control systems usually outweigh the disadvantages, and they are crucial for many industrial processes and applications. Figure 8: A timing diagram for the above applications SW-Switch P-Pump V-valve T-Timer C-Counter P1-Lower Limit of Pressure Level P2-Upper Limit of Pressure Level REFERENCES ● H. G. 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