Module 18 – Heat Exchangers & Refrigeration Systems

Objective:
By the end of this module, a trainee will be able to:

1. Understand the purpose and types of heat exchangers in a petrochemical plant.

2. Recognize the principles of heat transfer.

3. Understand refrigeration system principles used in butadiene and petrochemical plants.

4. Monitor and maintain heat exchanger and refrigeration performance.

5. Identify common issues and basic troubleshooting steps.

18.1 – Introduction to Heat Exchangers

Definition:

• Heat exchanger = equipment used to transfer heat from one fluid to another without mixing them.

Importance in Butadiene & Petrochemical Plants:

• Remove heat from reactors, condensers, compressors, and product streams.

• Maintain process temperature for reaction control and product quality.

• Recover heat in energy-saving applications.

Operator Role:

• Monitor inlet/outlet temperatures, pressure drop, and flow rates.

• Check for fouling, scaling, or leaks.

• Notify maintenance if performance drops.

Analogy:

• Heat exchanger = “car radiator transferring heat from engine to air or coolant.”

18.2 – Common Types of Heat Exchangers

• Shell & Tube

Tubes carry one fluid; shell carries the other

Monitor pressure drop, tube leaks, scaling

• Plate

Fluids flow through alternating plates

Check for gasket leaks, fouling

• Air Cooler / Fin Fan

Uses air to remove heat

Monitor air flow, fan operation, cleaning

• Condenser

Condenses vapor into liquid

Monitor pressure, temperature, and flow

• Reboiler / Cooler

Heat added or removed from process streams

Monitor temperature, level, and pressure

Operator Tips:

• Observe temperature approach (difference between hot outlet and cold outlet).

• Monitor pressure drops; high drop may indicate fouling or blockage.

• Ensure cleaning schedules are followed.

Recommended Visuals:

• Diagram comparing shell & tube, plate, and air cooler

• Flow indicators for operator monitoring

18.3 – Principles of Heat Transfer

Basic Concepts:

1. Conduction – Heat transfer through solid materials.

2. Convection – Heat transfer via moving fluid (liquid/gas).

3. Radiation – Heat transfer via electromagnetic waves (less common in process units).

Operator Relevance:

• Temperature differences drive heat transfer.

• Flow rate, fouling, and heat exchanger design affect efficiency.

Analogy:

• Conduction = “heat moving along a metal spoon in hot water”

• Convection = “boiling water circulating”

• Radiation = “heat from the sun”

18.4 – Refrigeration Systems

Purpose in Butadiene Plants:

• Maintain low temperatures for condensation, separation, and storage.

• Prevent vapor loss and maintain product quality.

Basic Components:

1. Compressor – Pressurizes refrigerant vapor.

2. Condenser – Cools vapor to liquid.

3. Expansion Valve – Reduces pressure and temperature of refrigerant.

4. Evaporator – Absorbs heat from process or storage stream.

Operator Role:

• Monitor refrigerant pressure, temperature, and flow.

• Check compressor operation and condenser cooling.

• Detect frost, leakage, or unusual noises.

Safety Considerations:

• Refrigerants may be toxic or flammable.

• High-pressure systems require caution during maintenance.

Analogy:

• Refrigeration system = “household refrigerator: compressor, condenser, expansion, evaporator.”

18.5 – Operator Monitoring & Basic Troubleshooting

Heat Exchangers:

• Low outlet temperature → check flow or fouling

• High pressure drop → strainer blockage, tube fouling

• Leak → isolate and notify maintenance

Refrigeration Systems:

• Low cooling → check refrigerant level, evaporator flow

• High pressure → condenser fouling, insufficient cooling water

• Compressor trip → check motor load, refrigerant pressure

Operator Tips:

• Use trend data for temperature and pressure to detect slow-developing problems.

• Always follow SOPs and safety guidelines for adjustments.

• Document observations and actions in logbooks.

18.6 – Preventive Measures & Operator Best Practices

1. Perform daily rounds to check temperatures, pressures, flows.

2. Ensure strain, dirt, or fouling is cleaned as per schedule.

3. Monitor refrigerant levels and compressor operation.

4. Communicate abnormalities to control room and maintenance.

5. Follow safety protocols for high-pressure and low-temperature systems.

Analogy:

• Operator = “caretaker ensuring heating/cooling systems in a building function properly.”

18.7 – Quiz / Knowledge Check

1. Name three types of heat exchangers and their operator considerations.

2. What are the main components of a refrigeration system?

3. How does fouling affect heat exchanger performance?

4. Why is monitoring temperature and pressure critical?

5. Give an analogy for heat exchangers and refrigeration systems in everyday life.

6. What should an operator do if refrigeration compressor trips unexpectedly?

18.8 – Media Sites Integration

• Videos:

  • Shell & tube heat exchanger operation overview

  • Refrigeration cycle animation and monitoring demonstration

  • Minor troubleshooting simulation

• Diagrams / Infographics:

  • Heat exchanger flow diagrams

  • Refrigeration cycle schematic

  • Operator monitoring panel illustration

• PDF Downloads:

  • Heat exchanger inspection checklist

  • Refrigeration monitoring guide

  • Preventive maintenance guide for exchangers

• Interactive:

  • Embedded quizzes

  • Scenario exercises: detect abnormal temperature/pressure and suggest operator action

18.9 – Summary & Key Takeaways

1. Heat exchangers transfer heat between fluids; proper monitoring ensures efficiency.

2. Refrigeration systems maintain low temperatures for condensation, separation, and storage.

3. Operators monitor temperatures, pressures, flow, and fouling to ensure performance.

4. Basic troubleshooting includes detecting leaks, low flow, high pressure, and abnormal trends.

5. Preventive observation and reporting are key to safe, reliable plant operation.