Regenerative Thermal Oxidizer (RTO) for Coating Industry
Click HereOverall Solution for VOCs Waste Gas Treatment in the Film Coating Industry
Treatment Target
- Organized emission <50 mg (non-methane total hydrocarbons);
- Energy saving, only use natural gas to start the furnace!
- Unorganized within the factory: non-methane total hydrocarbons <10mg/m3;
- After treatment, chimney emission indicators: nitrogen oxides <50mg/m3;
Collection of VOCS Exhaust Gas in Film Coating Plant
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Oven cross ventilation
The low-concentration exhaust gas from the rear oven is sent to the fresh air inlet of the front oven as fresh air, and is generally not passed into the first 2-3 high-concentration ovens. This method can reduce the exhaust volume of the coating machine.
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Coating head/glue room connected to oven in series
The low-concentration exhaust gas from the coating head/glue preparation room is sent into the fresh air inlet of the oven by a fan and used as fresh air for the oven (generally not passed into the high-concentration ovens in the first two sections). This method can reduce the exhaust volume of the coating head and glue preparation room, and avoid the low-concentration exhaust gas from entering the RTO to dilute the total concentration.
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Low-concentration exhaust gas large circulation form wind reduction – suitable for hot air heat recovery
Waste Heat Recovery Methods & Selection
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Steam waste heat recovery
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Heat transfer oil waste heat recovery
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With standby electric heating and waste heat recovery
Emissions of Exhaust Gas from Thin Film Coating VOCS
For example, a coating machine has 8 ovens, the total exhaust volume of the ovens is 10,000 m3/h, and the average temperature of the ovens is 140°C (the average temperature of the high and low temperature zones of the 8 ovens). Then the energy consumption of the oven of a coating machine is
Reference Exhaust Gas Volume of Coating Machine
| Coating product classification | Oven length | Reference exhaust air volume | Exhaust air temperature |
| Advertising consumables | 24 m～40m | 9000m³/h～ 10000m³/h | 60℃～80℃ |
| Anodized aluminum (transfer paper) | 12 m～24m | 8000m³/h～ 10000m³/h | 60℃～70℃ |
| Reflective film, reflective material | 24 m～72m | 7000m³/h～ 10000m³/h | 70℃～80℃ |
| Solar backplane film | 20 m～32m | 8000m³/h～ 10000m³/h | 70℃～80℃ |
| Aluminum-plastic film | 24 m～32m | 9000m³/h～ 12000m³/h | 70℃～80℃ |
| Tape | 16 m～28m | 10000m³/h～ 12000m³/ | 60℃～80℃ |
| Release film | 20 m～36m | 9000m³/h～ 10000m³/h | 60℃～100℃ |
| Protective film | 24 m～36m | 9000m³/h～ 10000m³/h | 70℃～80℃ |
| Lithium battery separator | about 28m | about 35000m³/h | 40℃～60℃ |
| Photosensitive film | about 60m | about 50000m³/h | 70℃～80℃ |
Properties of Common Solvents for Thin Film Coating
| Substance | Molecular formula | Molecular weight | Lower explosion limit (%) | Density Kg/L | Heating value Kcal/kg | Safe concentration (25%LEL) |
| Ethyl acetate EAC | C4H8O2 | 88 | 2.2 | 895 | 6101 | 21.6 g/m³ |
| Toluene | C6H5CH3 | 92 | 1.2 | 870 | 10138 | 12.3 g/m³ |
| Butanone | CH3COCH2H5 | 72 | 1.7 | 810 | 8098 | 13.6 g/m³ |
| Propyl acetate | C5H10O2 | 102 | 2 | 888 | 6770 | 22.7 g/m³ |
| Xylene | C8H10 | 106 | 1.2 | 870 | 10295 | 14.2 g/m³ |
| Methanol | CH3OH | 32 | 6 | 792 | 5688 | 21.4 g/m³ |
| Acetone | CH3COCH3 | 58 | 2.5 | 785 | 7363 | 16.2 g/m³ |
| Cyclohexane | C6H12 | 84 | 1.1 | 947 | 10012 | 10.3 g/m³ |
| Cyclohexanone | C6H10O | 98 | 1.1 | 950 | 8584 | 12.0 g/m³ |
| Ethanol | C2H6O | 46 | 3.3 | 790 | 7098 | 16.9 g/m³ |
| Isopropanol | C3H8O | 60 | 2 | 786 | 7902 | 13.4 g/m³ |
| 120# solvent oil | Mixture of n-heptane, isoheptane, cycloheptane, etc. | 1.1 | 766 | 10695 | 8.8 g/m³ |
Safe Concentration of VOCS Exhaust Gas
The concentration of organic gases in the air is usually expressed in g/m3. Taking ethyl acetate as an example
Classic Cases in Coating Industry
Shanghai Kaixinsen
The main products are: diffusion film, prism film, micro-transparent film, solar film and other functional films.
The project is divided into two phases, the first phase is 40,000 air volume RTO, and the second phase is 50,000 air volume RTO.
Phase I 40,000 air volume system flow chart
| Production line | Product width (mm) | Production line speed (m/min) | Oven |
| T2、T3 | 1520 | 13 | 5节 |
| W3 | 1520 | 20 | 5节 |
| W4 | 1520 | 20 | 5节 |
- Total exhaust gas volume: 40000m³/h
- Main components of exhaust gas: butanone, toluene
- Concentration of exhaust gas: 1800~3000mg/m³
- Residual heat utilization: thermal oil
Phase II 50,000 air volume system flow chart
| Production line | Product width (mm) | Production line speed (m/min) | Oven |
| T4 | 1520 | 13 | 5节 |
| T5 | 1520 | 13 | 5节 |
| W5 | 1520 | 13 | 12节 |
| W6 | 1520 | 13 | 12节 |
- Total exhaust gas volume: 50000m³/h
- Main components of exhaust gas: butanone, toluene
- Concentration of exhaust gas: 1800~3500mg/m³
- Residual heat utilization: thermal oil
Guangdong Xinrui New Material Technology Co., Ltd.
The main products are: transfer paper, transfer film, anodized aluminum, polyester film, window film, protective film, etc.
- Total exhaust gas volume: Phase I: 30,000 m³/h 1 unit
- Phase II: 20,000 m³/h 1 unit
- Phase III: 70,000 m³/h RTO+180,000 m³/h rotor 1 unit
- Main components of exhaust gas: toluene, ethyl acetate
- Exhaust gas concentration: 2,000~5,400 mg/m³
- Waste heat utilization: hot air
Enjie Zhuhai New Material Technology Co., Ltd.
Main products: Wet-process lithium battery separato
Production equipment exhaust situation
Wet-process lithium battery separator coating line (Japan line)
- Total exhaust gas volume: 80000m³/h 3 units
- Main components of exhaust gas: acetone, etc.
- Concentration of exhaust gas: 3500~7000mg/m³
- Residual heat utilization: steam
- Project features:
· Front-end LEL real-time concentration detection to ensure safety
· Pipeline fire dampers to ensure safety
· System maintains self-operation
· Emissions meet standards
Jiangxi Ruijie New Material Technology Co., Ltd.
Main products: Lithium battery aluminum plastic film
Production equipment exhaust situation
Lithium battery aluminum plastic film coating line (Japanese line)
- Total exhaust gas volume: 65000Nm³/h 2 units
- Main components of exhaust gas: ethyl acetate, butanone, methylcyclohexane, toluene, isopropanol.
- Exhaust gas concentration: 3500~7000mg/m³
- Waste heat utilization: hot air
Project features:
· Front-end LEL real-time concentration detection to ensure safety
· Pipeline fire dampers to ensure safety
· Gas collection boxes for unified collection
· Emissions that meet standards
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