Case Background
This is a real retrofit case—a plastic products company in Dongguan whose coating process generated organic solvent exhaust. Due to odor complaints from nearby residents, the environmental protection department required rectification.
The factory had previously used basic exhaust treatment equipment, but after rectification, exhaust was still being generated during production, with odor impacting nearby residents. This was already the company‘s fourth rectification.
The Root of the Problem: Why Previous Rectifications Failed
The exhaust treatment method previously used by the factory essentially did not solve the VOCs destruction problem.
Organic solvent exhaust that only passes through simple adsorption or filtration treatment means VOCs molecules are merely temporarily “intercepted” or “diluted,” not thoroughly decomposed. When adsorption materials become saturated or treatment efficiency declines, odor from exhaust still escapes to the surrounding area. For BOPP coating processes, solvents like ethyl acetate in drying exhaust have characteristics of high volatility and low olfactory threshold—even at low concentrations, they are sufficient to trigger complaints from nearby residents.
The Retrofit Solution: Why RTO
Facing repeated complaints and rectification requirements from the environmental protection department, the factory ultimately chose to install RTO (Regenerative Thermal Oxidizer) exhaust treatment equipment.
RTO works by heating exhaust to above 760°C, oxidizing and decomposing VOCs into carbon dioxide and water. Unlike previous treatment methods, RTO does not “transfer” or “dilute” pollutants—it thoroughly destroys them through high-temperature oxidation. RTO VOCs purification efficiency can reach over 99%, which is the fundamental path to resolving odor complaints.
Investment Scale
The factory invested over 3 million RMB for this RTO exhaust treatment facility.
Retrofit Results
After the retrofit was completed, conditions in the workshop and factory area changed significantly.
Odor eliminated in factory area. The factory manager stated: “The company installed a brand-new regenerative thermal oxidizer, and no odor can be smelled throughout the factory area.” During visits to the workshop and factory area, it was found that although there was still slight odor inside the workshop, no odor could be detected outside。
Resident complaints ceased. Residents who previously complained about the factory‘s exhaust odor stated that after environmental department inspections, they “could no longer smell odor,” and expressed approval of the rectification results. The factory manager also stated: “Now there are no more complaints from nearby residents.”
The Added Value of Heat Recovery
The RTO retrofit not only resolved environmental complaint issues but also brought energy-saving benefits.
The factory manager explained: “The heat generated by this equipment’s combustion can also be recycled and sent to the drying process, saving approximately 20% of energy.”
This is consistent with RTO‘s technical characteristic of heat recovery efficiency typically exceeding 90%. Recovered heat reused for oven heating directly reduces natural gas consumption, transforming RTO from a purely “pollution control device” into equipment with dual energy-saving functions.
Reference for Retrofit Timeline
Although this case did not disclose specific retrofit timeline data, based on general experience in the film coating industry for RTO retrofits, the production, installation, and commissioning cycle for a complete RTO system serving 2-3 coating lines is approximately 5-6 months. Installation requires foundation work and lifting conditions, with maintenance and inspection cycles typically every six months.
The Core Takeaway from This Case
Repeated rectifications are inferior to getting it right once. The factory went through four rectifications before finally resolving the problem. The methods used in the first three rectifications failed to fundamentally destroy VOCs, causing recurring problems. The introduction of RTO truly cut off the root of odor complaints.
Environmental investment can generate economic returns. RTO‘s heat recovery function saved the factory approximately 20% of energy consumption. In markets with higher natural gas prices, this proportion can be further amplified.
Proactive upgrading is superior to reactive rectification. The factory only underwent RTO retrofit under pressure from complaints and rectification requirements. If RTO is pre-installed during new factory planning or production line upgrades, losses from shutdown rectification and reputational impacts from complaints can be avoided.
Next Step
Want more detailed data on this case? Including before/after emission concentration comparisons, natural gas consumption changes, and payback period analysis? Request the complete case report.