07. MG3217 Kendali Proses S03: Ratio Control, Cascade Control dan Feedforward Control

Summary

This video discusses various advanced control strategies used in industrial processes, including ratio control, multilevel control, and feedforward control. The focus is on how these methods are applied in industries like metallurgy for processes such as combustion and fluid temperature regulation. Key concepts such as maintaining precise ratios between gases for combustion, using multiple controllers to improve response times, and anticipating disturbances before they affect the system are covered. The importance of understanding these principles for effective process control and optimization is emphasized, with an encouragement to apply these techniques in practical settings.

Takeaways

• 😀 Ratio control is commonly used in industries such as metallurgy, especially for controlling the ratio of gases in combustion processes like natural gas and oxygen.
• 😀 In ratio control, maintaining an exact balance between substances like natural gas and oxygen is crucial for optimal combustion, typically following a 2:1 mole ratio.
• 😀 In real-world applications, such as in factories, slight excess oxygen (e.g., 2.1 or 2.2) is often used to ensure complete combustion.
• 😀 Temperature control is closely integrated with ratio control, as adjusting the amount of oxygen and fuel affects the temperature output.
• 😀 A block diagram in ratio control shows the relationship between controlled variables, disturbances, and system outputs, with pressure being a major disturbance factor.
• 😀 Multilevel control systems, such as cascade control, are used to improve response times and prevent slow reactions in temperature-sensitive processes.
• 😀 Multilevel control works by having a primary controller regulate the main process and a secondary controller responding more quickly to disturbances like temperature fluctuations.
• 😀 A feedback control system alone might be slow to respond, so multilevel control anticipates disturbances more effectively by adjusting flow rates before significant errors occur.
• 😀 Feedforward control anticipates disturbances and adjusts control parameters before an error or deviation from the setpoint occurs, improving system stability.
• 😀 A combination of feedforward and feedback control systems is recommended to ensure minimal deviations and proactive response to disturbances, ensuring smoother operations in complex processes.

Q & A

What is ratio control, and where is it commonly applied?

Ratio control is a technique used to maintain a specific ratio between two or more variables in a process. It is commonly applied in industries like metallurgy, where controlling the ratio between gases, such as natural gas and oxygen in combustion processes, is critical for achieving perfect combustion.

Why is it important to control the ratio of natural gas to oxygen in industrial combustion processes?

Controlling the ratio of natural gas to oxygen is crucial for achieving efficient combustion. A proper ratio ensures that the combustion process is complete, minimizing waste and pollution. Excess oxygen is often used in factories to ensure that the combustion process is efficient and to prevent incomplete burning.

How does the example of the metallurgical industry illustrate ratio control in action?

In the metallurgical industry, natural gas and oxygen are used in a specific ratio (e.g., 2:1) for combustion. By controlling the flow of both gases, the process ensures that enough oxygen is available for complete combustion of the natural gas, leading to efficient energy production.

What role does temperature control play in ratio control systems?

Temperature control is integrated into ratio control systems to ensure that the desired temperature is achieved during processes like combustion. For instance, when heating substances in a furnace, the temperature is continuously measured and controlled by adjusting the flow of air or fuel based on the setpoint temperature.

What is a multilevel control system, and how is it used in industrial applications?

A multilevel control system involves using two or more control loops to regulate a process. It is often used when a single control system cannot react quickly enough. For example, in the heating of water using hot oil, a primary control loop regulates the water temperature, while a secondary control loop manages the temperature of the hot oil to prevent delays in response time.

What problems can arise with single-loop control systems in temperature control applications?

Single-loop control systems may not react quickly enough to changes, especially when there are significant delays in the system's response, such as when heating water with hot oil. This can lead to inefficient heating or overshooting the desired temperature, which can be mitigated by using multilevel control systems.

How does the feedforward control method anticipate disturbances?

Feedforward control anticipates disturbances by measuring variables that could potentially affect the system before they create errors. Unlike feedback control, which reacts after a disturbance has occurred, feedforward control adjusts the system in real-time to prevent deviations from the setpoint.

What is the advantage of using feedforward control combined with feedback control?

The advantage of combining feedforward and feedback control is that feedforward can quickly respond to anticipated disturbances before they cause errors, while feedback control corrects any residual errors. This combination ensures that the system remains stable and efficient, even when disturbances occur.

In the example of multilevel control for heating water, how does the secondary controller help improve the system's response?

The secondary controller in a multilevel control system for heating water regulates the temperature of the hot oil in the jacket surrounding the water tank. By adjusting the flow of hot oil in response to changes in its temperature, the secondary controller ensures that the water reaches the desired temperature more quickly, preventing delays that would occur with a single control system.

What are the key differences between conventional and typical control systems?

Conventional control systems rely on feedback to correct errors after they occur, while typical control systems, like the keskit system, anticipate changes and react more quickly. The keskit system uses multiple controllers and measuring instruments to ensure a faster and more accurate response to disturbances, improving system stability.