Module 12 – Plant Startup & Shutdown

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

1. Understand the purpose and importance of safe startup and shutdown.

2. Recognize the key steps and sequences involved in plant or unit startup.

3. Recognize the key steps and sequences involved in plant or unit shutdown.

4. Understand operator interventions and monitoring during these processes.

5. Apply safe practices and checklists to prevent accidents or equipment damage.

12.1 – Introduction to Startup & Shutdown

Definition:

• Startup = bringing the plant or a unit from idle or shutdown state to normal operation.

• Shutdown = taking the plant or a unit from normal operation to a safe, idle state.

Importance:

• Improper startup or shutdown can cause:

  • Safety hazards (fire, overpressure)

  • Equipment damage (thermal shock, mechanical stress)

  • Process upsets or off-spec product

Operator Role:

• Execute sequences according to SOPs

• Monitor key parameters and alarms

• Communicate with control room and maintenance

Analogy:

• Startup = “starting a car and gradually increasing speed safely”

• Shutdown = “parking and turning off engine carefully to avoid damage”

12.2 – General Principles of Startup

Preparation Steps:

1. Review SOPs and checklists.

2. Verify safety systems and interlocks are active.

3. Inspect equipment for readiness (valves, pumps, compressors).

4. Confirm availability of utilities (steam, cooling water, electricity, instrument air).

5. Check feedstock supply and quality.

Startup Sequence (Conceptual):

1. Pre-Startup Checks: verify all systems ready.

2. Equipment Warm-Up: gradually bring heaters, pumps, compressors online.

3. Flow Introduction: slowly introduce feedstock, monitor pressure and temperature.

4. Reaction Initiation: bring reactors to desired operating conditions.

5. Product Separation & Utility Coordination: start downstream separation and ensure utilities meet demand.

6. Ramp-Up to Normal Operation: adjust flow, temperature, and pressure gradually while monitoring trends.

Operator Tips:

• Never rush startup steps; follow SOP sequence.

• Observe alarms and abnormal trends carefully.

• Maintain communication with team during each stage.

Analogy:

• Startup = “warming up an oven before baking cake; gradual increase avoids burning or damage”

12.3 – General Principles of Shutdown

Preparation Steps:

1. Review shutdown SOPs.

2. Communicate intention to control room and team.

3. Ensure product storage or disposal is ready.

4. Confirm utilities and downstream equipment are available for safe shutdown.

Shutdown Sequence (Conceptual):

1. Gradual Feed Reduction: reduce feedstock flow slowly to prevent thermal or pressure shock.

2. Equipment Cool-Down: bring heaters, reactors, compressors to safe temperature.

3. Isolation: close valves, isolate pumps and compressors.

4. Depressurization / Purging: safely release pressure or purge lines with inert gas if needed.

5. Final Checks: confirm levels, pressures, and temperatures are within safe idle range.

6. Lockout / Tagout (LOTO): secure equipment for maintenance or long-term shutdown.

Operator Tips:

• Follow sequence exactly; skipping steps risks safety.

• Monitor trends for abnormal conditions.

• Maintain communication with team.

Analogy:

• Shutdown = “cooling down and turning off a car engine gradually, then applying handbrake and parking”

12.4 – Operator Monitoring During Startup & Shutdown

Key Parameters to Observe:

• Temperature, pressure, flow, level

• Alarms and interlocks

• Utility status (steam, cooling water, electricity)

• Product quality (conceptually)

Operator Responsibilities:

• Adjust manual valves or switches as per SOP.

• Monitor trending data and respond to abnormal conditions.

• Notify control room or supervisor immediately if unsafe conditions arise.

Analogy:

• Operator during startup/shutdown = “pilot adjusting controls during takeoff and landing”

12.5 – Safety Considerations

Hazards During Startup:

• Overpressure or vacuum in vessels

• Thermal shock in heat exchangers or reactors

• Gas leaks from introducing feed too quickly

Hazards During Shutdown:

• Overcooling or freezing in heat exchangers

• Residual pressure or flammable gases

• Improper isolation of utilities

Operator Tips:

• Always verify interlocks, alarms, and safety systems before each step.

• Use PPE as required.

• Never bypass safety systems.

12.6 – Conceptual Checklists for Operators

Startup Checklist (Conceptual):

1. Pre-startup inspection complete

2. Utilities available and verified

3. Safety interlocks active

4. Equipment warmed up and checked

5. Feedstock ready and quality verified

6. Communication with control room established

Shutdown Checklist (Conceptual):

1. Feed flow reduced gradually

2. Equipment cooled down safely

3. Valves and pumps isolated

4. Lines depressurized/purged

5. Levels and pressures safe

6. LOTO applied if required

12.7 – Quiz / Knowledge Check

1. What is the main purpose of startup and shutdown procedures?

2. Name three steps in a safe startup sequence.

3. Name three steps in a safe shutdown sequence.

4. Why is gradual feed introduction important during startup?

5. What is the operator’s role during startup and shutdown?

6. Give an analogy for plant startup and shutdown in everyday life.

12.8 – Suggested Media for Google Sites Integration

• Videos:

  • Conceptual animation of startup sequence

  • Conceptual animation of shutdown sequence

  • Operator monitoring and panel walkthrough

• Diagrams / Infographics:

  • Startup flowchart

  • Shutdown flowchart

  • Operator monitoring points and checklist

• PDF Downloads:

  • Conceptual startup checklist

  • Conceptual shutdown checklist

  • Safety precautions guide

• Interactive:

  • Embedded quizzes

  • Scenario exercises: respond to abnormal conditions during startup/shutdown

12.9 – Summary & Key Takeaways

1. Startup = bringing plant from idle to normal operation safely; shutdown = bringing plant to safe idle.

2. Following SOP sequences prevents accidents, equipment damage, and process upsets.

3. Operator monitoring, communication, and adherence to safety systems are critical.

4. Gradual ramp-up/ramp-down of feed, temperature, and pressure avoids hazards.

5. Checklists and pre/post-startup/shutdown inspections ensure safe and reliable operation.