Process Control Design Methodology Quiz

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Questions and Answers

What is the first step in the process control design methodology?

Identify the hazardous conditions

Identify the operating parameters

Identify the measurables

Understand the process (correct)

Which of these are NOT considered a measurable parameter in process control?

Redox/potential

Density

Flexibility (correct)

Conductivity

Which of these are NOT a commonly used measurement method for process control?

Infrared

Magnetic (correct)

Ultrasonic

Radiowaves

What is the purpose of setting control limits in the process control design methodology?

To ensure the process operates within safe and desired parameters (B) Signup and view all the answers

What is the purpose of defining a fail-safe system in process control?

To ensure the process can continue to operate safely in the event of a failure (D) Signup and view all the answers

What is the main purpose of integrating and testing the process control system with other systems?

To identify potential conflicts between systems (B) Signup and view all the answers

Which of these is NOT considered a major cause of failures in process control?

Unpredictable market fluctuations (B) Signup and view all the answers

Which of these steps in the process control design methodology is directly related to ensuring the system can handle unexpected events?

Create redundancy systems (A) Signup and view all the answers

What is the main objective of adding control to a water tank in a heating or cooling process?

To maintain water levels at operational conditions. (B) Signup and view all the answers

What role do level sensors play in managing a water tank?

They inform personnel about the water level. (C) Signup and view all the answers

What issue could arise from failing to maintain control over the water tank levels?

Water overflow from the tank. (B) Signup and view all the answers

Which of the following statements accurately describes the filling process of the water tank?

The tank is filled without any drainage occurring. (B) Signup and view all the answers

What could potentially happen if water levels in the tank are not monitored?

Potential overflows and operational disruptions. (D) Signup and view all the answers

What is the primary purpose of process control in chemical engineering?

To maintain process variables near desired values (C) Signup and view all the answers

Which of the following best describes a Distributed Control System (DCS)?

Manages interconnected processes across an entire plant (B) Signup and view all the answers

What is one of the key benefits of implementing process control in a chemical plant?

Improved safety measures (D) Signup and view all the answers

What distinguishes a Programmable Logic Controller (PLC) from a Distributed Control System (DCS)?

DCS controls an entire plant and interconnected processes (D) Signup and view all the answers

Which of the following is NOT a role of process control?

Increasing operator workload (C) Signup and view all the answers

How does full automation in chemical plants benefit operations?

It enhances the ability to communicate with field instruments (D) Signup and view all the answers

Which process control advantage helps minimize environmental impact?

Achieving optimal chemical ratios (B) Signup and view all the answers

What is a potential risk of poor process control in a chemical plant?

Decrease in safety standards (C) Signup and view all the answers

What is the purpose of the input variable in a control process?

It shows the effect of the surroundings on the process. (A) Signup and view all the answers

Which type of control system involves a single control variable and a single manipulated variable?

Single Input - Single Output (SISO) (A) Signup and view all the answers

What distinguishes disturbances in a control process?

They include inputs that cannot be controlled by an operator. (A) Signup and view all the answers

In a cascade control system, what role does the 'Master' controller play?

It sets the setpoint for the 'Slave' controller. (B) Signup and view all the answers

What is referred to as dead time in control systems?

The delay in the output after applying input. (A) Signup and view all the answers

Which function does the 'D' part of a PID controller represent?

Derivative Control (B) Signup and view all the answers

What characterizes a Multiple Input - Multiple Output (MIMO) control system?

Several controlled variables influenced by several inputs. (D) Signup and view all the answers

Which statement about manipulated outputs is true?

They can be controlled by the operator or control system. (B) Signup and view all the answers

What is the formula for calculating error in process controls?

Error = setpoint - process variable (A) Signup and view all the answers

Which part of a PID controller is responsible for integrating past error over time?

Integral Control (B) Signup and view all the answers

How does the output of a proportional control change?

It is proportional to the amount of error. (B) Signup and view all the answers

What does the term 'setpoint' refer to in process control?

The desired value for a controlled variable (D) Signup and view all the answers

Which process control activity includes safety and environmental protection?

Safety, Environment and Equipment Protection (D) Signup and view all the answers

In what hierarchy of process control activities is real-time optimization categorized?

Planning and Scheduling (A) Signup and view all the answers

What is the main purpose of a PID controller?

To automatically adjust system variables (C) Signup and view all the answers

Which control action would respond immediately to changes in the error signal?

Proportional Control (D) Signup and view all the answers

Which of the following are examples of why a process would need to be transitioned from one operational condition to another?

Economic considerations (A), Changes in product specifications (B) Signup and view all the answers

What is the primary objective of control in a process?

To ensure consistent and predictable results (D) Signup and view all the answers

What is the primary factor that causes a water tank to overflow when there is no drainage and it is being constantly filled?

Lack of sufficient tank capacity (D) Signup and view all the answers

What is the purpose of setting operational conditions and set points in a process?

To achieve optimal product quality and consistency (D) Signup and view all the answers

Which of the following is NOT a factor influencing the transition of a process from one operational condition to another?

Employee productivity (C) Signup and view all the answers

What is the purpose of adding control valves and level sensors to a water tank in a heating or cooling process?

To prevent the tank from overflowing or running dry (B) Signup and view all the answers

Which of the following is an example of an operational constraint that may necessitate a change in process conditions?

A new regulation prohibiting the use of certain chemicals (D) Signup and view all the answers

In the context of process control, what does the term 'set point' refer to?

The specific value at which a process variable should be maintained (C) Signup and view all the answers

Study Notes

Introduction to Process Dynamics and Control

Course name: Process Dynamics and Control
Course code: CH158-2P
Instructor: Engr. Louise Grace Avena-Ardeta

Process Control

Process control combines statistics and engineering principles to manage processes.
It involves mechanisms, architectures, and algorithms for process control.
Examples of tasks include: controlling water stream temperature, operating a jacketed reactor isothermally, maintaining reactant ratios in a reactor, and preventing tank overflow.

Further Objectives of Process Control

Safety is a crucial aspect, aiming to minimize environmental impact.
Optimizing processes involves maintaining process variables near desired values.

Distributed Control System (DCS)

Modern chemical plants often utilize full automation, facilitated by DCS.
DCS systems communicate with instruments in the field, aiding engineers and operators.

DCS vs PLC

Programmable Logic Controllers (PLC) manage individual machines.
Distributed Control Systems (DCS) manage entire interconnected plants.

Objectives of Control

Maintain processes at their operational conditions and setpoints.
For example, maintaining a water tank level in a heating/cooling process without drainage.

Design Methodology for Process Control

Understand the process.
Identify operating parameters.
Identify hazardous conditions.
Identify measurable elements (temperature, pressure, flow rate, pH, humidity, level, concentration, viscosity, etc.).
Select measurement points.
Select measurement methods (electric, pneumatic, light, radiowaves, infrared, nuclear).
Select a control method.
Design the control system.
Set control limits.
Define the control logic.
Create a redundant system (for fail-safe).
Establish lead/lag criteria.
Integrate and test the system with other systems.

Hierarchy of Process Control Activities

Activities involved in controlling a process span different time scales (days, hours, minutes, seconds).

Failures in Process Control

Real-world incidents like the Bhopal gas tragedy highlight the importance of safety controls.
Operational failures can be attributed to factors like equipment malfunctions and safety control failures.
Examples of relevant incidents are the Bhopal Gas Tragedy (1984) and the BP Texas City Refinery explosion (2005).
These case studies illustrate the risks associated with neglecting safety precautions in process control.

Definitions and Terminologies

Input Variable: The impact of surroundings on the processes.
Manipulated Output: A variable in the surroundings controllable by the system or operator.
Disturbances: Uncontrollable inputs influencing the process.
Output Variable: The variables that are the effect of a process on its surroundings.
Single Input Single Output (SISO): One input variable influences one output variable.
Multiple Input Multiple Output (MIMO): Multiple input variables influence multiple output variables.
Cascade Control: Two or more controllers working together (Master-Slave loops).
Dead Time: The time delay between a disturbance and its effect.
Derivative Control: Proportional response to the change rate of an error in the system.
Error: The difference between the setpoint and the process variable.
Setpoint: The desired value for process variable to attain.
Proportional Control: Proportional output in response to the system error.
Integral Control: Proportional output in response to the duration and amount of system error.
PID Controller: A controller consisting of proportional, integral, and derivative control actions.

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Description

Test your knowledge on the key concepts and steps involved in the process control design methodology. This quiz covers essential parameters, control limits, fail-safe systems, and the integration of process control systems. It also addresses measurement methods and common failures in process control.