Assignment 19 - Pumps

Pump Notes

Date: 30/05/2023

Pump

• A pump is a mechanical device used to transfer fluids (liquids or gases) from one place to another by creating pressure or suction. Pumps are widely used in various industries and applications to move liquids or gases through pipes or other conduits. Here are some common types of pumps and their typical uses:

• Centrifugal Pump: Uses centrifugal force to transfer fluid and is suitable for high flow rate applications. Examples include radial-flow and axial-flow pumps.

• Reciprocating Pump: Utilizes a piston or plunger to create a reciprocating motion, generating pressure and pumping fluid. Examples include piston pumps and diaphragm pumps.

• Rotary Pump: Relies on the rotation of gears, lobes, or screws to transfer fluid. Examples include gear pumps, screw pumps, and vane pumps.

• Diaphragm Pump: Employs a flexible diaphragm to pump fluids, making them suitable for corrosive, abrasive, or viscous substances.

• Peristaltic Pump: Features rotating rollers or shoes that compress and squeeze a flexible tube to move fluid. Also known as hose pumps or tube pumps.

• Gear Pump: Utilizes interlocking gears to transfer fluid, typically with a constant flow rate. Common types include external gear pumps and internal gear pumps.

• Axial Flow Pump: Moves fluid in a parallel direction to the pump shaft, ideal for applications requiring low head but high flow rates, such as in irrigation or drainage systems.

• Jet Pump: Uses a high-velocity jet of fluid to create a vacuum that draws and transports fluid from a well or reservoir. Often used in deep well pumping or water supply systems.

• Submersible Pump: Designed to operate while submerged in the fluid being pumped, commonly used in applications such as drainage, sewage, and groundwater pumping.

• Screw Pump: Utilizes one or more rotating screws to transfer fluid, providing a smooth and continuous flow. Common types include single-screw pumps and twin-screw pumps.

Each type of pump has its advantages and disadvantages, and their specific usage depends on factors such as the fluid being pumped, flow rate requirements, pressure considerations, and the environment in which they will be used. It is important to select the right type of pump based on the specific application to ensure optimal performance and efficiency.

Advantages and disadvantages of few of the above mentioned pumps are given below:

Centrifugal Pump

• Advantages:

• High flow rates: Centrifugal pumps can handle large volumes of fluid, making them suitable for applications that require high flow rates.

• Simple design: Centrifugal pumps have a relatively simple construction, which makes them easy to operate, maintain, and repair.

• Wide range of applications: Centrifugal pumps are versatile and can be used in various industries, including water supply, irrigation, HVAC systems, and chemical processing.

• Disadvantages:

• Limited suction lift: Centrifugal pumps have limitations when it comes to suction lift, meaning they may not be suitable for applications where the pump needs to pull fluid from a deep well or a distant source.

• Poor performance with high viscosity fluids: Centrifugal pumps are less efficient when handling highly viscous fluids, as their impeller design is optimized for low viscosity fluids.

• Limited pressure capabilities: Centrifugal pumps are not as effective at generating high pressures compared to other pump types, such as reciprocating pumps.

Reciprocating Pump:

Advantages:

• High-pressure capabilities: Reciprocating pumps can generate high pressures, making them suitable for applications requiring high-pressure fluid transfer.

• Versatility: Reciprocating pumps can handle a wide range of fluids, including corrosive and abrasive substances.

• Precise control: Reciprocating pumps offer precise flow control and can handle variable flow rates, making them suitable for applications requiring accurate dosing or metering.

Disadvantages:

• Complex design: Reciprocating pumps have a more complex design compared to centrifugal pumps, requiring more maintenance and higher operational costs.

• Vibrations and noise: Reciprocating pumps can produce vibrations and noise due to the reciprocating action, which may require additional measures to reduce noise levels.

• Limited flow rates: Reciprocating pumps typically have lower flow rates compared to centrifugal pumps, which may not be ideal for applications requiring high volumes of fluid transfer.

Diaphragm Pump:

Advantages:

• Ability to handle corrosive and abrasive fluids: Diaphragm pumps are suitable for pumping fluids that are corrosive, viscous, or contain solids, as the diaphragm acts as a barrier between the fluid and the pump components.

• Self-priming: Diaphragm pumps can self-prime, meaning they can start pumping without the need for external priming.

• Reversible operation: Diaphragm pumps can operate in both directions, allowing for pumping and reversing the flow as needed.

Disadvantages:

• Limited flow rates: Diaphragm pumps generally have lower flow rates compared to centrifugal pumps, which may not be suitable for applications requiring high volumes of fluid transfer.

• Limited pressure capabilities: Diaphragm pumps may not achieve as high pressures as reciprocating pumps, which can be a limitation in certain applications.

• Diaphragm wear and replacement: The diaphragm in diaphragm pumps may wear out over time and require periodic replacement, adding to maintenance costs.

It's important to note that these advantages and disadvantages may vary depending on specific pump models, manufacturers, and application requirements.

Pump Control Systems:

Here is 10 examples of pump control systems and their applications:

1. Constant Speed Control: Controls the pump to operate at a fixed speed, commonly used in applications where a constant flow rate is required, such as HVAC systems and water supply networks.

2. Variable Speed Control: Allows the pump speed to be adjusted based on the demand, providing energy efficiency and optimizing system performance. It is used in applications such as water treatment plants, irrigation systems, and industrial processes.

3. Pressure Control: Maintains a specific pressure setpoint by adjusting the pump speed or flow rate. It is used in applications like water distribution networks, booster pumps, and firefighting systems.

4. Level Control: Monitors and controls the liquid level in a tank or reservoir by adjusting the pump operation. It finds applications in wastewater treatment plants, sewage pumping stations, and industrial storage tanks.

5. Flow Control: Regulates the flow rate through the pump based on the required process flow, commonly used in chemical processing plants, food and beverage production, and pharmaceutical industries.

6. On/Off Control: Switches the pump on or off based on the system's demand. It is used in applications like sump pumps, dewatering systems, and small-scale irrigation.

7. Dual Pump Control: Controls two pumps to work alternately or together, providing redundancy and ensuring continuous operation in critical applications like water supply systems and firefighting networks.

8. PID Control: Utilizes a Proportional-Integral-Derivative (PID) algorithm to maintain precise control of pump parameters such as pressure, level, or flow. It is commonly used in complex industrial processes and HVAC systems.

9. Remote Monitoring and Control: Enables remote monitoring and control of pump systems through a centralized control center or mobile devices. It is used in large-scale water distribution networks, wastewater treatment plants, and remote pumping stations.

10. Energy Optimization Control: Implements advanced algorithms to optimize pump operation based on energy efficiency, load demand, and system conditions. It finds applications in energy-intensive industries, such as oil and gas, where energy savings are crucial.

These are just a few examples of pump control systems and their applications. The choice of control system depends on the specific requirements of the pumping application, system dynamics, and energy efficiency goals.

Example: Constant Speed Control System for a Pump

Description:

The Constant Speed Control system maintains a fixed speed for the pump to achieve a constant flow rate. The system consists of a pump, a speed controller, and flow rate measurement sensors.

Required I/Os:

• 1 digital output (DO) for pump control

• 2 analog inputs (AI) for flow rate measurement

• 1 analog output (AO) for speed control

CODESYS ST Code:

PROGRAM ConstantSpeedControlSystem VAR     // Constants     DesiredFlowRate: REAL := 100.0; // Desired flow rate in m^3/hr     // Variables     ActualFlowRate: REAL;  // Actual flow rate measured by sensors     PumpSpeed: REAL := 50.0; // Initial pump speed in Hz PROGRAM Main     // Main program logic goes here     // Read actual flow rate from sensors     ActualFlowRate := ReadFlowRate();     // Calculate the error between desired and actual flow rates     VAR         Error: REAL := DesiredFlowRate - ActualFlowRate;     END_VAR     // Adjust pump speed based on the error     IF Error > 0.0 THEN         PumpSpeed := PumpSpeed + 1.0; // Increase pump speed by 1 Hz     ELSE         PumpSpeed := PumpSpeed - 1.0; // Decrease pump speed by 1 Hz     END_IF     // Set the pump speed output     SetPumpSpeed(PumpSpeed);     // Other program logic goes here END_METHOD METHOD ReadFlowRate: REAL     // Code to read the flow rate from sensors goes here     // Replace this with your actual implementation     // Return the measured flow rate     RETURN 95.0; // Sample value END_METHOD METHOD SetPumpSpeed(speed: REAL)     // Code to set the pump speed output goes here     // Replace this with your actual implementation     // Set the pump speed output     // Example: PumpSpeedOutput := speed; END_METHOD

In this example, the Constant Speed Control system uses a digital output (DO) to control the pump, two analog inputs (AI) to measure the flow rate, and one analog output (AO) to adjust the pump speed. The CODESYS ST code reads the actual flow rate from sensors, calculates the error between the desired and actual flow rates, adjusts the pump speed based on the error, and sets the pump speed output.

Please note that this is a simplified example, and you will need to adapt the code to your specific PLC hardware and configuration.

Example: Variable Speed Control System for a Conveyor Belt in an Industrial Process

Description:

In an industrial process, a conveyor belt is used to transport materials from one point to another. To optimize the conveyor belt operation and energy efficiency, a Variable Speed Control system can be implemented. This system adjusts the speed of the conveyor belt based on the material load, ensuring smooth operation and reducing energy consumption.

Industrial Process: Material Sorting and Packaging System

Hardware Requirements:

- Variable frequency drive (VFD) to control the motor speed of the conveyor belt

- Proximity sensors to detect the presence of materials on the conveyor belt

- Programmable Logic Controller (PLC) with appropriate digital and analog inputs/outputs

- Human-Machine Interface (HMI) for operator interaction and monitoring

Number of I/Os Required:

- 1 digital input (DI) for start/stop control of the conveyor belt motor

- 1 analog input (AI) for measuring the material load on the conveyor belt

- 1 analog output (AO) to adjust the motor speed of the conveyor belt

Functional Requirements:

1. Start/Stop Control:

- The system should allow the operator to start and stop the conveyor belt motor using a push button or HMI interface.

2. Material Load Detection:

- Proximity sensors should detect the presence of materials on the conveyor belt and provide input to the PLC.

- The analog input should measure the material load level on the conveyor belt.

3. Speed Adjustment:

- The PLC should analyze the material load input and adjust the motor speed accordingly.

- The speed adjustment should be smooth and gradual to avoid sudden changes in conveyor belt speed.

4. Speed Range Limit:

- The system should have predefined minimum and maximum speed limits for the conveyor belt motor.

- The speed should not exceed these limits to ensure safe and efficient operation.

5. Alarm and Indication:

- The system should generate an alarm or display a notification if the material load exceeds the safe operating range.

- The HMI should provide visual indications of the conveyor belt status and any alarm conditions.

CODESYS ST Code:

PROGRAM VariableSpeedControlSystem VAR     // Constants     MinSpeed: REAL := 10.0;   // Minimum speed of the conveyor belt motor in Hz     MaxSpeed: REAL := 50.0;   // Maximum speed of the conveyor belt motor in Hz     // Variables     MaterialLoad: REAL;       // Material load level on the conveyor belt     ConveyorSpeed: REAL;      // Speed of the conveyor belt motor METHOD Main     // Main program logic goes here     // Read the material load level from the analog input     MaterialLoad := ReadMaterialLoad();     // Adjust the conveyor belt speed based on the material load     ConveyorSpeed := CalculateConveyorSpeed(MaterialLoad);     // Set the motor speed of the conveyor belt     SetConveyorSpeed(ConveyorSpeed);     // Other program logic goes here END_METHOD METHOD ReadMaterialLoad: REAL     // Code to read the material load level from analog input goes here     // Replace this with your actual implementation     // Return the measured material load level     RETURN 0.75; // Sample value between 0 and 1 representing load percentage END_METHOD METHOD CalculateConveyorSpeed(materialLoad: REAL): REAL     // Code to calculate the conveyor belt speed based on material load goes here     // Replace this with your actual implementation     // Return the adjusted conveyor belt speed     RETURN (materialLoad * (MaxSpeed - MinSpeed)) + MinSpeed; END_METHOD METHOD SetConveyorSpeed(speed: REAL)     // Code to set the motor speed of the conveyor belt goes here     // Replace this with your actual implementation     // Set the motor speed output     // Example: ConveyorSpeedOutput := speed; END_METHOD

In this example, the Variable Speed Control system adjusts the speed of the conveyor belt motor based on the material load level. The CODESYS ST code reads the material load from the analog input, calculates the desired conveyor belt speed, and sets the motor speed output accordingly.

Please note that this is a simplified example, and you will need to adapt the code to your specific PLC hardware and configuration.