Product News
0102030405
Applications of RTO in Different Industries
2025-09-04
1. Applications of RTO in the Packaging Printing, Coating, and Painting Industries
The packaging printing, coating, and painting industries are significant sources of VOC emissions in the light industry. Production uses large amounts of ink, thinners, adhesives, and other materials, with the drying process producing VOC waste gases, including toluene, xylene, and ethyl acetate.
Industry characteristics:
- VOC emissions in packaging, printing, and coating industries are characterized by large air volume and high concentration (up to 12 g/m³). The purification efficiency of RTO must reach over 99.8%.
- These industries generally have a demand for waste heat recovery. The technology of "RTO + waste heat recovery (steam, hot water, thermal oil, etc.)" is widely applied.
- Painting industry VOC emissions are marked by large air volume, low concentration, and dust. Exhaust contains toxic substances like benzene and xylene, requiring treatment levels for both below 10 mg/m³ and RTO efficiency above 99.5%.
- Waste gases from PVC products, rubber, and graphite drying contain dust and greasy aerosols, requiring regular cleaning and replacement of the bottom ceramic heat storage media. Technologies such as "baghouse dust removal" and "quick replacement of the bottom heat storage media" are often adopted.
Based on the above characteristics, leading enterprises such as Wahaha, Dali Foods, Amcor Group, and China Tobacco in the packaging printing industry; Lucky Film, Enjie Co., and Bluesail Medical in the coating industry; and BYD, Shaanxi Auto, and Geely in the painting industry, have widely adopted third-generation Rotary RTO systems, all of which have been operating stably for more than four years.
3.2 Applications of RTO in the Waterproof Membrane Industry
During the production of asphalt waterproof membranes, VOC emissions are generated from the asphalt mixing reactors, asphalt membrane production lines, and asphalt storage tanks. Asphalt fumes are a complex mixture containing a large number of polycyclic aromatic hydrocarbons (PAHs) and small amounts of heterocyclic compounds containing oxygen, nitrogen, and sulfur. They typically exist in the air as aerosols. Studies have identified more than 80 PAHs in asphalt fumes, including benzo[a]pyrene, benz[a]anthracene, and carbazole. Asphalt fumes are mainly composed of gas and liquid phases.
Figure 3.1 Rotary RTO for End-of-Pipe Treatment in the Waterproof Membrane Industry
Industry characteristics:
- The exhaust gas contains a large amount of dust and viscous liquid-phase high-boiling hydrocarbons, which can easily block the heat storage media.
- The emission requirements are stringent, with the industry standard being NMHC <10 mg/m³.
- High energy efficiency is required for RTO.
Treatment route and advantages of Rotary RTO technology:
- To address the issue of clogging of the bottom heat storage media, the three-bed RTO "reverse burning" technology is not adopted (since reverse burning cannot meet emission standards). Instead, the Rotary RTO "quick replacement of the bottom heat storage media" technology is chosen. An inspection port is set between the clogged bottom heat storage layer and the second-to-bottom layer, allowing rapid replacement of the clogged bricks.
Figure 3.2 Quick Replacement Structure of Bottom Heat Storage Media in Rotary RTO
- Rotary RTO systems use rubber-contact rotary valves with very high sealing performance, achieving purification efficiencies above 99.8%, fully meeting VOC emission requirements of <10 mg/m³.
- Rotary valves have a long service life and low failure rate, while Rotary RTO systems also have lower investment costs.
Based on these characteristics, leading enterprises in the waterproof membrane industry, such as Oriental Yuhong and Keshun Waterproof, have completely replaced their three-bed RTO systems with Rotary RTO systems.
2. Applications of RTO in the Chemical Industry
The pharmaceutical and fine chemical industries (chemical additives, stabilizers, etc.) are significant sources of VOC emissions. Their VOC emissions are complex in composition and have fluctuating concentrations. Typical difficult-to-treat components include halogenated hydrocarbons such as dichloromethane and chloroform, ammonia, triethylamine, hydrogen chloride, hydrogen sulfide, and occasionally hydrogen fluoride.
Industry characteristics:
- The exhaust gases often contain chlorine, sulfur, and ammonia, which can cause equipment corrosion and blockages of ammonium salts in the heat storage media.
- Exhaust gases containing nitrogen-based organics produce NOx after decomposition.
- Wide fluctuations in VOC concentration, sometimes with sudden spikes, pose significant safety risks.
Treatment route and advantages of Rotary RTO technology:
- The treatment route of "pretreatment (acid-alkali scrubbing + dehumidification) + rotary RTO + post-treatment (SCR + acid-alkali scrubbing)" is adopted. In the low-temperature regions of the equipment, anti-corrosion materials, coatings, fast drainage, and preheating technologies are applied.
- To prevent and mitigate ammonium salt blockages, techniques such as exhaust preheating, hot air purging, bottom brick washing, and quick replacement are employed.
- A combined rotary RTO + SCR process is used for NOx removal.
- Safety measures include safety distances, concentration buffering tanks, optimized sampling times for concentration detection, a "two-out-of-three" strategy with FID detectors, predictive safety software, HAZOP analysis, and SIL classification, among others, to ensure the intrinsic safety of the plant.
Based on these characteristics, leading companies such as Simcere Pharmaceutical, Sichuan Pharmaceutical, Lianhong Group, Sinochem Lantian, and Yangnong Chemical have adopted Rotary RTO systems as the core equipment for VOC treatment.
3. Applications of RTO in the Petrochemical Industry
In ABS resin, ethylene, polypropylene, maleic anhydride, EVA plants, as well as wastewater treatment plants, tank farms, and loading/unloading stations, RTO is applied for VOC treatment.
Industry characteristic:
1. Exhaust gases contain oily aerosols, macromolecular polymers, dust, and particulates. For example, ABS plants Emit Vocs with acrylonitrile, subject to an emission limit of 0.5 mg/m³.
2. High emission standards must be met, with a general requirement of <20 mg/m³.
3. Large fluctuations in exhaust concentration and volume.
Treatment route and advantages of Rotary RTO technology:
- Depending on the exhaust composition, various pretreatment processes (such as bag filters, saddle-ring filters, and primary cryogenic cooling) are employed. To address blockages caused by dust and high-boiling copolymers, the "reverse burning" process is avoided. Instead, quick replacement of bottom heat storage bricks is implemented.
- Rotary RTO systems use a single rotary valve for gas distribution, ensuring stable and reliable operation with a low failure rate. They are particularly advantageous for large airflows.
- Valve seals use labyrinth structures combined with rubber-contact sealing technology, achieving near "zero leakage" and purification efficiency up to 99.8%. This ensures that high-concentration VOCs (up to 12 g/m³) can still meet the emission requirement of <20 mg/m³.
- For stringent emission requirements such as acrylonitrile at 0.5 mg/m³, a "secondary series air distribution" solution is adopted.
- Rotary RTO systems have smaller footprints and lower energy consumption, making them particularly suitable for retrofitting in older plants.
Based on these characteristics, the petrochemical industry has widely adopted Rotary RTO systems. In China, more than 200 successful cases have been implemented, including Shanghai Gaoqiao Petrochemical, Guangxi Beihai Refining & Chemical, Dushanzi Tianli Henghua, and Shandong Yulong Petrochemical.