Refining and Petrochemical Company HAZOP Minute Sheet

Project: Crude Distillation Unit

Node: 3

Draw No:2

Node Description: Preflash Furnace (10-H-02)

Guide Word

Cause

Consequence

Safeguards

Recommendation

1. High Flow of feed

1. Increased pumping capacity of feed pump10-P-25AB

2. Crude feed line valve PV1 fully opene

3. Crude feed flow controller 10-FRC-1051 faulty

1. High level in preflash column causing column offset

2. Low temperature of preflash column feed

1. High flow alarm should be installed

2. Frequent checking and maintenance of flow controllers and valves

2. Low Flow of feed

1. Low head of crude feed pump 10-P-25AB

2. Feed valve PV1 partly blocked

3. Feed flow controller 10-FRC-1051 failed

4. Fouling of preflash furnace tubes

5. Ruptured heater tubes

1. Low level in preflash column

2. Pump cavitations and leaks

1. Low flow alarm installation suggested

2. Check and clean furnace tubes when choked with coke

3. Regular checking and maintenance of flow controller and valves

4. Clean heat exchangers tubes when blocked

3. No Flow of feed

1. Pump 10-P-25AB fails

2. Feed valve PV1 fully blocked

3. Feed flow controller 10-FRC-1051 faulty

4. Fouling of preflash furnace tubes

5. Ruptured heater tubes

1. Furnace pipe will be chocked with coke

2. Low level in preflash column causing pump cavitations and leaks

1. Install spare feed pump to auto start if pump 10-P-25AB fails

2. Check and maintain flow controller and valves regularly

3. Inspect heat exchangers and flow lines and clean them when dirty

4. High Flow of fuel

1. Temperature controller 10-TRC-1137 faulty

2. Fuel oil flow controller FR-1146 faulty

3. Fuel gas flow controller FR-1149 faulty

4. Fuel oil valve PV3 fully opened

5. Fuel gas valve PV4 fully opened

1. Coking in furnace tubes

2. Fouling of furnace tubes

1. Regular inspection of fuel valve and circulation system

2. Check temperature controller regularly

5. Low flow of fuel

1. Temperature controller 10-TRC-1137 faulty

2. Fuel oil flow controller FR-1146 faulty

3. Fuel gas flow controller FR-1149 faulty

4. Fuel oil valve PV3 partially blocked

5. Fuel gas valve PV4 partially blocked

1. Low coil outlet temperature

1. Frequent inspection of fuel valves

2. Check and maintain temperature controller

6. Low Flow of atomizing steam

1. Steam control valve PV2 faulty

1. Incomplete combustion

2. Smoke generation

1. Install steam-air ratio with low steam rate alarm

7. As well as High Flow of primary air

1. High draught

1. Increased stack loss

2. Reduced furnace efficiency

1. Install air-fuel ratio controller

8. As well as low Flow of primary air

1. Low draught

1. Incomplete combustion.

2. Loss of fuel

1. Install air-fuel ratio controller

9. High Temperature

1. Furnace temperature controller 10-TRC-1137 faulty

2. Fuel oil flow controller FR-1146 faulty

3. Fuel gas flow controller FR-1149 faulty

4. Fuel oil valve PV3 fully opened

5. Fuel gas valve PV4 fully opened

1. Cracking of crude feed

2. High crude temperature may cause pressure build up and rupture furnace tubes

1. Regular checking and maintenance of heater temperature controller

2. Install high temperature alarm

3. Frequent checking of heater fuel valves

10. Low Temperature

1. Temperature controller 10-TRC-1137 faulty

2. Fuel oil flow controller FR-1146 faulty

3. Fuel gas flow controller FR-1149 faulty

4. Fuel oil valve PV3 partially blocked

5. Fuel gas valve PV4 partially blocked

6. Fouling in heater tubes

1. Low coil outlet temperature into preflash column

1. Regular check and maintain temperature controllers

2. Check fuel flow valves frequently.

3. Inspect crude preheat train regularly

11. High Pressure

1. High temperature in furnace causing release of light ends

1. Expansion of hot oil and consequent rupture of furnace tubes

1. Install pressure controller

2. Install high pressure alarm