#TechTalk – Semiconductor Manufacturing: Manages Emissions from Etching and Cleaning

Evolution of VOC Abatement Technologies

Traditional methods like scrubbers or direct incineration were inefficient for low-concentration VOC streams. The rotary concentrator and thermal oxidizer system provide an energy-efficient, scalable solution that is now the standard for emission control.

Rotary Concentrator

Function
The rotary concentrator optimizes the RTO by concentrating low-concentration VOCs, improving performance and cost-efficiency.

Key Components

• Rotating Wheel: Made of zeolite or activated carbon, it adsorbs VOCs.
• Segregated Sections:
  • Adsorption Zone: Low-VOC air is passed through and adsorbed onto the wheel.
  • Desorption Zone: Heated air desorbs VOCs.
  • Cooling Zone: Regenerates the wheel.
  • Pre-Filtration: HEPA filters or mist eliminators remove particulates, prolonging media life.

Operational Parameters

• Adsorption Temperature: 20°C–40°C
• Desorption Temperature: 180°C–250°C
• Airflow Rates: 1,000 to 100,000 SCFM.

Removal Efficiency
Achieves VOC concentration ratios of 10:1 to 20:1, improving RTO efficiency.
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Regenerative Thermal Oxidizer (RTO)

Function

The RTO destroys VOCs and HAPs via high-temperature oxidation, converting them to CO₂ and H₂O.

Key Components

• Heat Exchangers: Ceramic media recover heat, with up to 97% efficiency.
• Burner: Maintains high temperatures (1,400°F–1,600°F).
• Chambers and Valves: Ensure optimal heating and cooling.

Process Flow

1. Concentrated air enters the RTO.
2. Air passes through ceramic media for preheating.
3. VOCs are oxidized in the combustion chamber.
4. Clean air exits, transferring heat to incoming air.

Removal Efficiency

Achieves up to 98% VOC destruction efficiency.

Benefits

• High Destruction Efficiency: Meets the strictest regulations.
• Energy Savings: Through heat recovery.
• Robust Design: Ensures long-term operation.

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Combined System Advantages

Synergy

• Cost Efficiency: Reduced air volume lowers fuel consumption.
• Compact Design: Smaller RTOs due to reduced flow rates.
• High Performance: Meets regulatory requirements.

Quantitative Analysis

• A 10:1 concentration ratio reduces fuel costs by up to 70%.
• Energy savings reduce carbon emissions.

Applications

• Paint and Coating: Controls overspray and curing VOCs.
• Semiconductor Manufacturing: Manages emissions from etching and cleaning.
• Printing: Reduces VOCs from ink drying.
• Chemical Processing: Controls off-gases from reactors.

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Maintenance and Operational Considerations

Rotary Concentrator

• Inspection: Check the wheel for wear.
• Cleaning: Ensure efficiency.
• Filter Monitoring: Clean or replace pre-filters.

RTO

• Ceramic Media: Inspect for damage.
• Burner Calibration: Ensure combustion efficiency.
• Valve Inspections: Prevent leakage.

Predictive Maintenance

IoT-based monitoring minimizes downtime and costs.