Instrumentation

Lecture 1 PPT

📘 IRP #1 – Introduction to Flow Diagrams & Materials Selection

(Theoretical summary of all pages – including image-only slides – based on )

1️⃣ Course Idea & Structure – Why This Matters 💡

This course is about how to design industrial processes — especially chemical and biotech systems — and how to make them:

Technically sound
Controllable
Economically viable
Safe and reliable

Two major pillars:

🔧 A) Instrumentation & Design

How to design processes
How to choose components and instruments
How to make PFDs and P&IDs
How to evaluate costs

🎛️ B) Process Control

How to control chemical and biotech processes
Understanding control loops
Learning PID control
Implementing in PLC systems

Employers want engineers who understand this whole chain — not just theory, but how real plants work.

2️⃣ Industrial Control Systems ⚙️

Industrial processes never run perfectly on their own. They are constantly affected by:

Disturbances
Changes in feed composition
Temperature variations
Pressure fluctuations

To keep the system stable, we use control loops.

🔁 The Control Loop – Core Concept

A basic control loop consists of:

Setpoint (SP) → Desired value
Process Variable (PV) → Measured value
Sensor + Transmitter → Measures PV
Controller → Compares SP and PV
Control element (valve/pump) → Adjusts process
Feedback loop

The controller calculates an error:

e = SP - PV

It then adjusts the manipulated variable (u).

🎛️ PID Control

PID =

P → Proportional
I → Integral
D → Derivative

⚠️ Important: PID ≠ P&ID

PID → Control algorithm
P&ID → Diagram

PID control is often implemented in PLCs (Programmable Logic Controllers).

3️⃣ Where Is Process Control Used? 🌍

Practically everywhere:

🧪 pH Control

Fermentation
Coagulation

🌡 Temperature Control

Cooking
Brewing
Pasteurization

💨 Pressure Control

Filtration
Water distribution

📏 Level Control

Tanks
Reactors

Control systems are fundamental in biotech and chemical engineering.

4️⃣ The Exam Structure 🎓

Mini project (design + control)
Group defense
Pass/fail grading

The theoretical goal: Understand how to design and control a process from scratch.

5️⃣ The Design Process 🏗

Design is systematic:

Problem statement
Planning
Implementation
Financial evaluation

Engineering is not just calculations — it includes economics.

6️⃣ Process Flow Diagrams (PFD) 🗺

A PFD shows:

Major equipment
Process flow
Basic connections

It does NOT show:

Instrumentation details
Control logic

It’s an overview.

📊 PFD with Mass Balances

A more detailed PFD includes:

Flow rates
Compositions
Material balances

This links chemical engineering theory with process design.

7️⃣ P&ID – Process & Instrumentation Diagram 🔍

A P&ID is much more detailed than a PFD.

It includes:

Sensors
Transmitters
Controllers
Valves
Pumps
Signal lines

It shows how control loops are physically implemented.

This is what plant operators and engineers actually use.

8️⃣ ISA 5.1 Instrument Nomenclature 🏷

Standard naming system.

First letter = measured variable:

Letter	Meaning
T	Temperature
P	Pressure
L	Level
F	Flow

Following letters = function:

Letter	Meaning
I	Indicator
R	Recorder
C	Controller
T	Transmitter
V	Valve
S	Switch
Y	Compute
AH	High alarm
AL	Low alarm

Example:

PIC = Pressure Indicator Controller

This standardization is critical in industry.

9️⃣ Control Valves (Image Slide Explained) 🚪

Different valve types:

Globe valves
Diaphragm valves
Three-way valves

Valves regulate flow — they are final control elements.

🛑 Valve Failure Modes

Important safety concept:

Fail open
Fail closed
Fail locked
Failure mode indeterminate

Failure position depends on safety requirements.

Example:

Cooling water valve → often fail open
Fuel supply → fail closed

🔌 Signal Types in P&ID

Electric analog:

4–20 mA (industry standard)

Pneumatic:

Instrument air (older systems, explosive areas)

Binary:

On/off (solenoids)

Software links:

Internal digital communication

Modern plants mainly use electric signals.

Instrument lines are drawn lighter than process lines.

🖥 Instrument Location Symbols

Symbols indicate:

Field mounted
Local panel mounted
Control room mounted
PLC / Distributed control system

This tells you where the instrument physically resides.

🔁 Example: Flow Control

Two ways to control flow:

1️⃣ Valve after pump 2️⃣ Variable pump speed

Valve control = cheaper Pump speed control = more energy efficient

Design is always a trade-off between CAPEX and OPEX.

🔬 Unit Operations

Core building blocks of process plants:

Distillation
Gas–gas operations
Liquid–liquid separation
Liquid–solid operations
Reactors
Heat exchangers
Gas & liquid handling
Solid transport

Understanding these helps you interpret PFDs.

🧪 Tank with pH Control (Design Exercise)

Continuous Stirred Tank Reactor (CSTR):

Requirements:

Maintain constant pH
Maintain constant level
Maintain retention time

So you need:

pH sensor + transmitter
pH controller
Acid dosing pump/valve
Level sensor
Level controller
Possibly flow control

Everything must communicate via signals.

This integrates:

Process design
Instrumentation
Control theory

🧱 Materials Selection

Critical engineering decision.

Must consider:

Operating conditions:

Temperature
pH
Salts
Erosion

Fabrication:

Welding
Casting
Machining

Corrosion resistance

Use chemical resistance charts.

Wrong material = failure.

💰 Design Case: Batch vs Continuous Fermentation

You must:

Design system
Select materials
Scale up
Estimate CAPEX
Estimate OPEX

This links engineering to business reality.

🎓 Mini Project

Apply everything to your own case.

You design:

Process
Control strategy
Equipment
Materials
Economics

Then defend it.

This simulates real engineering practice.

🧠 Big Picture Takeaways

This lecture establishes:

How processes are structured
How control loops work
How diagrams represent reality
Why standardization (ISA) matters
Why material selection is critical
Why economics cannot be ignored

It connects: Chemical engineering + Instrumentation + Control theory + Economics.

Quiz

Score: 0/30 (0%)

Q0. In the context of the lecture, what is the main difference between a PFD and a P&ID?

A PFD shows the control algorithm, while a P&ID shows only material costs.

A PFD gives a process overview, while a P&ID gives detailed instrumentation and control information.

A PFD is only used for batch processes, while a P&ID is only used for continuous processes.

A PFD shows only electrical signals, while a P&ID shows only chemical reactions.

Q1. Why is it important to understand both process design and process control in industrial biotechnology or chemical engineering?

Because process control replaces the need for equipment design.

Because process design determines what is built, while process control determines how it is operated safely and consistently.

Because process control is only used during exams, not in real plants.

Because material selection is unrelated to process operation.

Q2. In a basic feedback control loop, what does the controller compare?

The pump speed and valve size

The setpoint and the measured process variable

The material cost and the operating cost

The PFD and the P&ID

Q3. What does the process variable represent in a control loop?

The desired target value chosen by the operator

The measured value of the controlled process parameter

The purchase price of the control valve

The theoretical value shown only in the PFD

Q4. What is the function of a sensor and transmitter in a control loop?

To physically mix the contents of a reactor

To measure a process variable and send that information to the controller

To estimate capital costs

To replace the need for a valve or pump

Q5. Which statement correctly distinguishes PID from P&ID?

PID is a diagram, while P&ID is a control algorithm.

PID refers to proportional-integral-derivative control, while P&ID refers to a process and instrumentation diagram.

PID and P&ID mean exactly the same thing.

PID is only used for material selection, while P&ID is only used for cost estimation.

Q6. Why are PLCs important in industrial control systems?

They are used only to draw process flow diagrams.

They are programmable devices that can execute control logic for industrial processes.

They eliminate the need for sensors.

They are chemical reactors used for fermentation.

Q7. According to ISA-style instrument naming, what does the first letter usually represent?

The equipment cost

The measured variable

The operator's name

The material of construction

Q8. What does the instrument code PIC most likely mean?

Pressure Indicator Controller

Pump Internal Connection

Process Instrument Cost

Programmable Industrial Compressor

Q9. In ISA-style notation, what does the letter T usually mean when it is the first letter of an instrument tag?

Transmitter

Temperature

Tank

Timer

Q10. Why can the meaning of the letter T depend on its position in an instrument code?

Because the first letter describes the measured variable, while later letters describe instrument function.

Because T always means tank regardless of position.

Because ISA codes are random and have no standard structure.

Because T means temperature only in fermentation systems.

Q11. Why might a variable-speed pump be more efficient than controlling flow only with a downstream valve?

Because it avoids wasting energy by forcing flow through a partly closed valve.

Because it removes the need for any control loop.

Because it is always cheaper to purchase than a valve.

Because it can measure pH directly.

Q12. In a pH-controlled continuous stirred tank reactor, which combination of instruments would be most relevant?

pH sensor, pH transmitter, pH controller, and acid dosing control element

Only a thermometer and a pressure alarm

Only a distillation column and a heat exchanger

Only a PFD without any control loop

Q13. Why is level control important in a continuous stirred tank reactor?

Because level affects tank volume and therefore retention time.

Because level control directly changes the molecular weight of the product.

Because level control replaces the need for pH control.

Because level is only relevant in gas pipelines.

Q14. Which factor is most directly relevant to materials selection for process equipment?

Temperature, pH, salts, erosion, corrosion resistance, and fabrication method

Only the color of the equipment

Only the name of the process diagram

Only whether the process is drawn in draw.io

Q15. A PFD contains complete information about sensors, valves, pumps, signal lines, and automation logic.

True

False

Q16. A P&ID is generally more detailed than a PFD.

True

False

Q17. In a feedback control loop, the setpoint is the measured value coming from the sensor.

True

False

Q18. The error in a control loop is commonly understood as the difference between the setpoint and the process variable.

True

False

Q19. PID control and P&ID diagrams refer to the same concept.

True

False

Q20. Temperature control can be relevant in cooking, fermentation, brewing, and pasteurization.

True

False

Q21. Pressure control may be relevant in filtration and water distribution systems.

True

False

Q22. The first letter in an ISA-style instrument code usually describes the function of the instrument, not the measured variable.

True

False

Q23. In ISA-style notation, F can indicate flow as the measured variable.

True

False

Q24. Instrument signal lines are normally drawn the same way as process piping lines on a P&ID.

True

False

Q25. Electric 4–20 mA signals are commonly used in modern industrial plants.

True

False

Q26. Pneumatic signals are only theoretical and are never found in real industrial plants.

True

False

Q27. A valve failure mode can be important for process safety.

True

False

Q28. Material selection should consider both process conditions and fabrication methods.

True

False

Q29. Batch and continuous fermentation systems can differ in design, control strategy, scale-up approach, CAPEX, and OPEX.

True

False