Understanding Automation and Control Systems in Pneumatic Conveying Operations
Automation refers to processes that execute functions independently, without requiring manual intervention from humans or other machines. It encompasses a variety of technologies aimed at minimizing human involvement through predetermined decision criteria and machine-based processes.
What is Automation? Automation broadly describes technologies designed to decrease human input by utilizing established decision-making criteria and relationships between subprocesses. This is accomplished through various means, including mechanical, hydraulic, pneumatic, electrical, and electronic devices, often in combination with computers.
Types of Automation: Logic-Based vs. Non-Logic-Based In practical terms, a manual process might involve an individual carrying a bucket of water to the second floor of a building, while an automatic process could use an electric pump to do so. This pump performs a single function without integrated logic.
Conversely, automation systems with pre-defined logic can adjust operations based on conditions. For example, a home water heater or thermostat uses logic to manage the heating process by activating and deactivating heat based on adjustable temperature cut-off points.
Additional logic can also enhance automation systems, such as programmed settings for different times of the day to improve user comfort.
Automation Modules Overview Effective automation typically relies on three key modules:
- Input Module (Measurement): This module measures essential conditions, like room temperature, to assess required actions.
- Controller Module / Processor Module (Logic): Equipped with programmed logic, this module decides when to issue commands to the output module, such as a thermostat signaling the HVAC system based on temperature changes.
- Output Module (Action): This module executes commands received from the controller, such as opening or closing valves in response to temperature readings.
Advanced Logic Automation Deepening our understanding of logic in automated systems, it is essential to differentiate between types of logic. The second category (Processor Module) features continuously adaptable logic, incorporating data and experience to refine operations.
Certain automated systems employ “Fuzzy Logic,” which adjusts operational logic based on previous behaviors. Advanced temperature-regulating systems may allow for slight temperature fluctuations instead of strict precision. Additionally, some robotic systems operate within defined parameters, making internal decisions independently from the programmer’s direct input.
Automation in Bulk Material Handling In pneumatic conveying and bulk material handling industries, the second type of automation (Controller or Processor Module) is prevalent.
Automation not only reduces labor costs and enhances production speed but also increases system reliability, allowing for greater operational efficiency.
Input-Processor-Output Systems in Automation More sophisticated automation uses Input-Processor-Output (I/O) systems. These systems can remember and execute machine instructions, incorporating multiple input and output variables—sometimes exceeding 100. The complexity and number of I/Os depend on the required automation level and whether the control is managed locally or remotely.
Manual operations in conveying systems can lead to challenges, especially when operators lack a thorough understanding of the system design. Given that even minor errors can result in significant financial losses, implementing a well-designed automated control system is crucial.
Troubleshooting I/O Systems In pneumatic conveying, if solids are introduced into a line without adequate airflow velocity, blockages can occur. To mitigate this risk, the solids feeder should only be activated once the airflow is established, typically after the blower has operated for five minutes. This interlocking function prevents potential blockages by halting the feeder if airflow ceases.
Types of I/Os
- Point I/Os (Digital I/Os): These inputs convey single-set values, such as a level sensor indicating whether a powder level has been reached.
- Pressure/Vacuum Relief Valves: These are adjustable to defined pressure set points.
- Pressure and Temperature Switches: These can send varying output signals based on adjustable high and low set points.
Digital I/Os typically transmit signals via voltage (e.g., 24 V DC or 120 V AC), while Analog I/Os operate through sensors, capable of measuring a range of values and sending signals in 4-20 mA current or 0-10 V depending on the configuration.
Programming Logic and Functional Descriptions Numerous PLC models require various programming languages, making it impractical for a programmer to master every software type. However, the essential operational sequence falls under the expertise of a pneumatic conveying designer, who produces a Functional Description (FD). This allows experienced programmers to develop the necessary code using the provided PLC software.
Programming Software Types PLC manufacturers provide two primary software types:
- Development Software: This sophisticated software is primarily for programmers writing complex code and is often utilized by conveying system suppliers.
- Client Software: More user-friendly and less expensive, this software allows end-users to make minor adjustments to the program without altering the overall structure, such as setting user access levels.
By understanding these foundational concepts of automation and control systems, stakeholders can effectively implement and optimize pneumatic conveying systems for greater efficiency and reliability.