Five Years of Safe and Stable Ultra-Low Emission Operation of Regenerative Thermal Oxidizer
Five Years of Safe and Stable Ultra-Low Emission Operation of Rotary Valve Regenerative Thermal Oxidizer — A Phenol-Acetone Petrochemical Project in Shanghai
The Vocs Treatment project for a phenol-acetone plant in Shanghai, undertaken byYurcent Environmental Technology, has been operating successfully since 2018 for over five years. The purification efficiency reaches up to 99.5%, with thermal efficiency as high as 97.3%, achieving ultra-low NMHC emissions below 20 mg/m³. At the same time, the high thermal efficiency of the Rotary Valve Regenerative Thermal Oxidizer saves more than 7,000 m³ of fuel gas consumption per day, realizing both environmental compliance and energy-saving benefits.
1. Project Background
In 1981, China's first large-scale cross-industry and cross-department petrochemical enterprise — Sinopec Shanghai Petrochemical Company — was established. Over the past four decades, it has gradually developed into a ten-million-ton refining base and clean fuel production base in Shanghai, becoming a key production enterprise within the Sinopec system and an important energy production base in Shanghai.
During the “13th Five-Year Plan” period, the company invested a total of RMB 1.373 billion in safety and environmental protection projects, completing more than 260 projects related to safety hazard rectification and environmental protection, including ultra-low emission upgrades, wastewater treatment upgrades, and comprehensive VOCs control projects. The company actively promoted six major green development initiatives and established a full-process, full-coverage environmental protection management system covering source prevention, process control, and end-of-pipe treatment.
2. Waste Gas Source
The 200,000 tons/year phenol-acetone unit located in the Shanghai Chemical Industry Park, Jinshan District, Shanghai, carried out an ultra-low emission upgrade for comprehensive VOCs treatment in 2017. The details are as follows:
| Process Unit | 200,000 Tons/Year Phenol-Acetone Unit |
| Waste Gas Source | Process tail gas from the phenol-acetone unit, high-contaminated oil tanks, tank farm, and loading crane waste gas |
| Main Components of Waste Gas | Benzene, Acetone, Phenol, and Non-Methane Total Hydrocarbons (NMHC) |
| Waste Gas Air Volume | ≥ 40,000 m³/h |
| Waste Gas Temperature | Ambient Temperature |
| Ultra-Low Emission Requirement | NMHC ≤ 20 mg/m³ |
3. Design Solution
The project adopted the technical route of “buffer air mixing + Regenerative Thermal Oxidizer” for VOCs treatment. After technical evaluation and selection, the project finally chose the third-generation technology product — the Rotary Valve Regenerative Thermal Oxidizer.
Figure: RTO Skid-mounted System
4. Advantages of Rotary Valve Regenerative Thermal Oxidizer
As a third-generation technology product, the rotary valve regenerative thermal oxidizer demonstrates outstanding performance in operational safety, stable environmental compliance, operational reliability, and economic efficiency.
The rotary valve RTO mainly consists of a combustion chamber, ceramic regenerative beds, a rotary valve, and a combustion system. The furnace body is divided into 12 chambers, including 5 inlet chambers for waste gas, 5 outlet chambers for purified gas, 1 purge chamber, and 1 isolation chamber.
The rotary valve is continuously and uniformly driven by a motor. Under the action of the distribution valve, the waste gas continuously switches slowly among the 12 chambers. The sealing structure of the rotary valve RTO adopts lip-type rubber seals, and the sealing materials are selected for wear resistance, temperature resistance, and corrosion resistance.
Figure 3: RTO Skid-mounted Process Flow and Online Monitoring
5. Operating Performance
The project has been in operation since 2018. Analysis of the five-year operating performance has fully demonstrated the advancement of the third-generation rotary valve RTO technology:
- The purification efficiency reaches up to 99.5%, and the measured emission value at the stack outlet has remained stably below 20 mg/m³ for a long period.
- The thermal efficiency reaches as high as 97.3%, saving more than 7,000 m³ of fuel gas per day compared with the previous treatment equipment.
- The footprint is 36% smaller than the second-generation three-bed RTO;
- The pressure fluctuation during valve switching is extremely small, only ±25 Pa. In addition, the rotary valve distributes gas into the furnace continuously without interruption, causing no impact on upstream production facilities.
- There has never been any production limitation or shutdown caused by the RTO equipment, and no emission exceedance has occurred during operation.
While achieving ultra-low NMHC emissions below 20 mg/m³, the rotary valve RTO also saves more than 7,000 m³ of fuel gas consumption daily due to its high thermal efficiency, ultimately realizing both environmental compliance and energy-saving benefits.