In asphalt mixing plants, particularly during the production of recycled materials, substantial quantities of high-concentration asphalt exhaust gases are generated. The challenges lie in the gases’ high concentration, their content of dust and particulates, and the large air volumes involved—typically exceeding 35,000 to 40,000 m³/h. Current regulations, such as GB 16297-1996 “Integrated Emission Standard for Air Pollutants,” mandate that asphalt exhaust emissions be kept below 20 mg/m³. Conventional technologies—including plasma electrostatic precipitation, activated carbon filtration, and scrubber-based gas cleaning—along with direct incineration in the primary drying drum, all fall short of meeting these stringent requirements, making compliance difficult. Moreover, operating costs are a critical factor; excessive energy consumption can significantly drive up production expenses, rendering solutions unaffordable for users. Consequently, highly efficient, low‑energy exhaust‑gas treatment systems are an urgent need for customers. Wuxi Xue Tao Group Co., Ltd. and its subsidiaries, drawing on practical experience and years of expertise in manufacturing asphalt recycling mixers and boilers, have developed the ROIE‑I series VOCs incineration system (a two‑stage TO furnace) combined with waste‑heat recovery equipment. This integrated solution effectively addresses both challenges: it efficiently treats asphalt exhaust gases to meet strict emission standards while reducing operating costs, delivering dual benefits of economic efficiency and environmental protection.

The operating principle of the ROIE‑I system for VOCs (secondary TO furnace) at Wuxi Xue Tao is as follows: During asphalt mixing, the asphalt exhaust gases are fed into the TO furnace, where they are thoroughly mixed with combustion air and burned. The natural gas used for combustion generates a high temperature of approximately 750–800°C within the furnace, oxidizing and decomposing pollutants such as benzo[a]pyrene, asphalt fumes, and total non-methane hydrocarbons into carbon dioxide and water, thereby eliminating odors. The gases after high‑temperature decomposition fully meet environmental standards, and the recovered waste heat is entirely reused to preheat the aggregates in the asphalt mixing equipment, ensuring no thermal energy is wasted.

Case:

A VOCs incineration system (a two‑stage TO furnace) and a waste‑heat recovery unit from Wuxi Xue Tao’s ROIE‑I series were installed on an imported asphalt mixing plant at a company in Suzhou to treat asphalt exhaust gases. Following this environmental‑protection upgrade, the plant has already produced over 20,000 tonnes of asphalt mixtures, including more than 6,000 tonnes of reclaimed material. During operation, third‑party testing by a specialized agency confirmed that all emission parameters fall well below regulatory limits; notably, odors have been completely eliminated, with no adverse impact on nearby residents. The facility has now been running continuously for approximately 30 days without a single complaint, effectively resolving the customer’s longstanding challenges and demonstrating the technology’s excellent performance in treating asphalt exhaust gases.

Following field tests at construction sites in Shanghai, Suzhou, and other locations, the asphalt exhaust gas treated by this solution exhibits a substantial reduction in concentration, well below the emission standard of 20 mg/m³ for asphalt fumes, fully meeting environmental protection requirements. In terms of operational energy consumption, an effective heat‑recovery system ensures efficient energy utilization; coupled with the high‑efficiency treatment provided by a two‑stage thermal oxidizer, the overall cost is only RMB 2–3 per ton of material, representing a significant reduction compared with conventional treatment approaches. This approach effectively mitigates the environmental impact of asphalt exhaust gases, minimizes risks to nearby residents and the ecological environment, and avoids penalties and shutdowns associated with non‑compliant emissions, delivering substantial environmental and social benefits.

The use of VOCs incineration (a two-stage thermal oxidizer) combined with waste‑heat recovery equipment for treating asphalt exhaust gases is technically feasible and economically viable. It effectively addresses the challenge of handling high‑concentration asphalt emissions, complies with stringent emission standards, and reduces operational energy consumption and costs, thereby meeting both environmental protection requirements and economic efficiency goals.