Questions and Answers
What is the high-level alarm threshold for the scrubber solvent?
The level switch LS-001 is used to monitor the low level of the scrubber solvent.
False
What is the average flow rate of the recirculation pump for the scrubber solvent?
0.2 m3/min
During normal operation, the temperature of scrubber solvent must be less than ______.
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Match the following indicators with their functions:
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What is the time it takes to replenish the scrubber solvent from the lower level (15 %)?
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Which temperature indicates a high temperature alarm for the scrubber solvent?
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What is the purpose of the VOC system control philosophy?
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What does VOC stand for?
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The drain valves for the Building Area VOC treatment unit are normally kept open.
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The two carbon polisher tanks in the Building Area VOC treatment stream have a volume of ______ m3.
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What is the alarm set point for the high pressure drop in the normal process control system?
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What action is required if the temperature inside the carbon polisher tanks exceeds 100°C?
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What is the consequence of a VOC concentration greater than 0.24 ppm at the outlet of the carbon polisher tanks?
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Which equipment monitors the pressure drop across the carbon polisher tanks?
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The blowers in the tank farm area VOC system operate automatically and do not require manual intervention.
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Study Notes
Equipment Identification
- Equipment includes level switches (LS-002, LS-003), pressure differential indicator transmitters (PDIT-003 to PDIT-006), and temperature indicator transmitters (TIT-002, TIT-003).
- Specific IDs and locations for each equipment noted, e.g., LS-002 located at 39-WBA-001 and TIT-002 at 39-PVP-002.
VOC System Control Philosophy
- Project focused on the VOC Area in Veolia Central Utilities and Waste Valorization Plant, contractor: Power Energy Gulf for Environmental Services Company.
- Document revision date is July 21, 2024.
Normal Process Control System
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Level Monitoring:
- VOC solvent scrubber levels monitored with LS-001 (high) and LS-002 (low).
- Normal operating range for solvent is maintained at 15-20%.
- Physical level observation possible through a level hose.
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Solvent Recirculation System:
- Average flow rate of recirculation pump is 0.2 m³/min.
- Time to fill scrubber:
- From 0-15%: approximately 16.2 minutes.
- From 15-20%: approximately 5.4 minutes.
- Total fill time from empty to normal level is about 22 minutes; replenishment from lower level (15%) takes about 6 minutes.
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Pressure Drop Monitoring:
- Monitored across carbon polisher vessels using PDITs, normal pressure range is 10-25 inches WC.
- Alarm set at 25 inches WC for high-pressure drop.
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Temperature Monitoring:
- Scrubber solvent temperature monitored via TITs.
- Must remain below 60°C; alarm for exceeding this temperature.
- Inline cooler is OFF if temperature stays below 60°C.
Emergency/Shutdown Process Control System
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Level Alarms:
- High-level alarm (>25%) alerts operator to drain scrubber solvent manually.
- Low-level alarm (<15%) prompts operator to fill scrubber with fresh solvent.
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High-Pressure Drop Alarm:
- Alarm triggered if pressure drop exceeds 25 inches WC (~62.5 mbar), action required: replace carbon bed.
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High-Temperature Monitoring:
- Cooler activates if solvent temperature exceeds 55°C to reduce it to 50°C.
Building Area VOC Treatment
- Two carbon polisher tanks (39-HAA-005, 39-HAA-006) with a volume of 60 m³ each.
- Instrumentation includes pressure differential indicator transmitters (PDIT-001, PDIT-002) and temperature gauges (TG-001, TG-002).
- High-pressure drop alarm set at 10 inches WC (~25 mbar) for operation.
Tank Farm Area VOC Treatment
- Gaseous VOC-laden air process involves passing through flame arrestors, inline gas pipe cooler, and knockout tank.
- Equipment includes blowers and VOC solvent scrubber system for treatment with biodiesel.
Condensate Knockout Drum
- Level of condensate monitored with level indicator transmitter set at a high level of 30%.
- Pneumatic control valves and pressure indicator transmitters regulate and monitor system pressure and temperature at blowers.
- Normal operation pressure drop is maintained between 40-50 inches WC (~100-125 mbar).
Key Processing Steps
- Treatment involves passing through multiple stages including carbon polishers with specific design for safe and reliable operation.
- Continuous monitoring and alarms ensure minimal operational intervention and safety of the VOC treatment process.### Blow Down Pump Operation
- Pump 39-PVP-001 is activated based on a 30% level set point from the HMI.
- Signal sent to solenoid valve VE-001 prompts the operator to manually open drain valve 39-RD-201 of the condensate knockout drum.
Pneumatic Control Valve Functionality
- In case of low or no flow from the tank farm (Veolia Incinerator operational), suction pressure drops below 25 inches of WC (~62.5 mbar).
- Pneumatic control valve 39-VC-001 is adjusted to increase airflow, ensuring volumetric capacity of the blower by drawing in atmospheric air.
- Valve 39-VC-001 is a fail-to-open type, with its positioner calibrated for a suction side pressure set point of 10 inches of WC (~25 mbar).
ON/OFF Valve Operation Logic
- Valve 39-VA-001 operates 3 minutes per hour, controlled by a timer on the HMI integrated with the PLC.
- Operational logic:
- When incineration is ON:
- Close 39-VA-001, open for 3 minutes
- Open valves 80-VA-001 and 80-VA-002
- When incineration is OFF:
- Open 39-VA-001
- Close valves 80-VA-001 and 80-VA-002
- When incineration is ON:
Pressure Monitoring
- If pressure drop across the VOC treatment system reaches 60 inches of WC, an alarm triggers.
- Operators must either replace carbon media or reduce scrubber solution level to restore normal operation.
Temperature Regulation
- Inline air cooler 39-EL-201 activates automatically if the blower discharge air temperature exceeds 55°C, cooling down to 50°C.
- If air temperature surpasses 60°C due to air cooler failure, an alarm activates and the blower trips automatically.
VOC Solvent Scrubber and Carbon Polisher Vessel
- Specific instrumentation equipment regulates the control and monitoring systems within the VOC solvent scrubber and carbon polisher in the tank farm area.
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Explore the intricacies of the VOC System Control Philosophy for the Veolia Central Utilities and Waste Valorization Plant. This quiz covers the principles and processes involved in ensuring effective environmental management systems in industrial settings. Test your knowledge on best practices and regulatory compliance related to VOC control.
