Regenerative Thermal Oxidizer for the Ink and Coating Industry

I. Introduction to Ink Production

Ink and similar product manufacturing refers to the production of colored paste-like substances for printing, as well as inks for computer printers and copiers. These are made by mixing, grinding, and blending pigments, binders (such as vegetable oils, mineral oils, resins, and solvents), and fillers.

During production, solvents are used to disperse and dissolve materials. Common solvents include toluene, xylene, ethyl acetate, propyl acetate, n-propanol, isopropanol, anhydrous ethanol, polyurethane, propylene glycol methyl ether acetate, etc.

Key production processes include mixing, stirring, grinding, dispersing, filling, and cleaning. Among these, mixing, stirring, and grinding are the primary sources of VOC emissions.

II. Overall Technical Solution for VOCs Waste Gas Treatment in Ink and Coating Manufacturing

1. Selection of Treatment Technology Route

The ink industry emits large but dispersed volumes of VOCs. The composition of waste gas varies due to differences in production processes and raw materials, posing specific treatment challenges. Enterprises should select treatment technologies that are appropriate for their specific conditions.

Typical VOC concentration in ink production line waste gas: 900–1,500 mg/m³; exhaust air volume: 10,000–20,000 m³/h. This constitutes a high air volume, medium-concentration VOCs emission scenario.

Considering both environmental protection and operational cost savings, the proposed treatment route is "Front-end Filtration + RTO" for managing waste gas from ink production lines. Specific steps are as follows:

1. Collect VOC emissions from various production processes.
2. Pass the mixed organic waste gas through a front-end filtration system to remove dust and particulates, preventing clogging of the RTO’s regenerative ceramic bed.
3. The pre-treated gas is directed via pipelines to a rotary RTO for high-temperature combustion, ensuring compliance with emission standards after treatment.

Figure 1: VOCs Waste Gas Treatment Process Flow Diagram

2. Factors in Selecting Treatment Equipment

1) Filtration Equipment Selection
Dry filters are typically used for waste gas filtration. Standard options include primary filters (G3/G4) and medium-efficiency filters (F5/F6), which offer high dust retention, good air permeability, modular design for easy assembly, and long service life.

• G3 efficiency: For particles ≥5.0μm, filtration efficiency 70% > E ≥ 50% (equivalent to U.S. standard L5).
• G4 efficiency: For particles ≥5.0μm, filtration efficiency 90% > E ≥ 70% (equivalent to U.S. standard L6).
• F5 efficiency: For particles ≥1.0μm, filtration efficiency 50% > E ≥ 30% (equivalent to U.S. standards M9, M10).
• F6 efficiency: For particles ≥1.0μm, filtration efficiency 80% > E ≥ 50% (equivalent to U.S. standards M11, M12).

2) Incineration Equipment Selection
The mainstream technologies for downstream incineration are RCO and RTO. Given the complex solvent composition in ink production, which can easily lead to catalyst poisoning and deactivation, and the high investment cost of high-air-volume RCO systems (with a typical catalyst lifespan of only around 8,000 hours and high replacement costs), RTO is selected as the downstream treatment method.

Since the VOC concentration is only 900–1,500 mg/m³, a rotary RTO with lower self-sustaining energy consumption is chosen.