Case 3: RTO with Waste Heat Recovery for Phthalic Anhydride Tail Gas (Xinbao Coal Chemical)
Project Overview
This is a tail gas treatment project for a 40kt/a phthalic anhydride production plant. The flue gas contains phthalic anhydride, maleic anhydride, benzoic acid, naphthoquinone, sulfur dioxide and other substances, with complex components and acidic media. The system needs to realize VOC purification and waste heat recovery simultaneously to maximize economic benefits.
Core Parameters
- Design gas treatment capacity: 75,000 Nm³/h
- Combustion temperature: 850℃
- Annual operating hours: 8,000
Process Solution
Integrated process: Desulfurization Tower + Three-Chamber RTO + Waste Heat Boiler
Process Flow: Production Tail Gas → Desulfurization Tower → Mist Eliminator → RTO Incinerator → Waste Heat Boiler → Chimney Discharge
Pre-desulfurization: Wet desulfurization tower removes acidic gas such as SO₂ to prevent corrosion on high-temperature equipment.
High-temperature Incineration: Organic pollutants are fully oxidized and decomposed inside RTO, with VOC removal efficiency ≥ 99%.
Waste Heat Utilization: High-temperature flue gas enters the heat pipe boiler to produce saturated steam for energy recovery.
Main Equipment
Desulfurization tower & circulating pump, three-chamber RTO, ceramic regenerator, pneumatic poppet dampers, 8t/h heat pipe waste heat boiler, explosion-proof fans, electrical & instrument assemblies.
Operation Performance
- Emission: VOC, NOₓ and particulate matter all reach industrial emission standards, no peculiar odor.
- Energy Benefit: The boiler produces 8.8 tons of saturated steam per hour. The annual income from waste heat far exceeds operating costs, realizing waste-to-energy.
- Equipment Durability: Pre-desulfurization reduces acid corrosion; the outer shell temperature of RTO is controlled below 65℃.
- Maintenance: Modular design, convenient inspection and replacement of components.
Technical Highlights
- Integrated design of desulfurization, incineration and waste recovery, suitable for acidic organic waste gas from coal chemical industry.
- Stable operation with small pressure fluctuation during valve switching.
- Equipped with FM/IRI certified burner and flame monitoring devices for multi-level safety protection.