01. Overview
Driven by the global “Dual Carbon” targets, the solar photovoltaic (PV) industry has achieved rapid explosive growth. China has ranked first in the world for consecutive years as the largest exporter of PV products. Nevertheless, complex waste gas pollutants generated during photovoltaic panel manufacturing have become a major bottleneck restricting the green and low-carbon development of PV enterprises. Multiple production procedures, ranging from silicon wafer cleaning to chemical vapor deposition (CVD), produce waste gas with diverse and complex compositions. Belonging to the pan-semiconductor sector, the solar PV industry shares highly similar waste gas characteristics with integrated circuits and optoelectronic display manufacturing, leading to high treatment difficulty. CADAIR focuses on pan-semiconductor waste gas treatment and adheres to the core principle of classified collection and combined treatment, providing customized, stable, and compliant waste gas treatment solutions for global PV manufacturers.
02. Industry Waste Gas Characteristics
Accurate analysis of waste gas characteristics is the premise of efficient purification in the PV manufacturing industry. The industry features three prominent exhaust characteristics:
- Wide Pollution Sources: Waste gas is discharged throughout multiple production processes, including silicon wafer cleaning, oxidation, wet/dry etching, ion implantation, and CVD.
- Complex & Variable Compositions: Various pollutants are continuously generated during production, including acidic exhaust, alkaline exhaust, organic volatile gas, and special process gas.
- Diversified Pollutant Types: Acidic exhaust derives from wafer cleaning, oxidation and etching processes; alkaline exhaust is mainly produced in cleaning and dry etching procedures; organic waste gas contains acetone, isopropanol and other common solvents; special process gas covers dopant gas, arsine (AsH₃), phosphine (PH₃), silane (SiH₄), nitrogen trifluoride (NF₃), etc.
Additionally, the waste gas generated by the PV industry is also commonly found in semiconductors, electronic manufacturing, precious metal processing and chemical nitration industries.
03. Waste Gas Treatment Challenges
Due to the complex physical and chemical properties of PV manufacturing exhaust, traditional single treatment technologies cannot meet industrial emission standards. The core challenges faced by PV waste gas treatment are summarized as follows:
- Mixed Exhaust Components: Acidic gas, alkaline gas, organic VOCs and special toxic gas coexist. A single treatment process is incapable of synchronous purification of diverse pollutants.
- High Safety Hazards: Highly toxic gases (AsH₃, PH₃) and spontaneous combustion gases (SiH₄) impose strict requirements on the safety, airtightness and stability of treatment equipment.
- Strict Emission Standards: Multiple regions have tightened environmental regulations, and the emission limits of NMHC, NOx and other indicators are close to detection thresholds.
- High Operation Costs: Continuous treatment of high-airflow exhaust leads to massive energy consumption and high operating costs, increasing the economic burden on manufacturers.
- 24/7 Production Demand: PV production lines operate uninterruptedly all year round; any equipment failure will cause huge economic losses to enterprises.
04. Customized Waste Gas Treatment Solutions
Targeting the above industry pain points, CADAIR independently develops a systematic purification solution based on gas classification + combined treatment. We flexibly match diversified treatment technologies according to pollutant types and physical & chemical characteristics to ensure long-term stable and compliant emission of all types of PV waste gas.
4.1 Process Scheme List
| Waste Gas Type | Treatment Technology/Solution | Key Process/Features |
| VOCs (Organic Waste Gas) | Zeolite rotor concentration + Combustion technology | Realize the conversion of high-airflow low-concentration waste gas to low-airflow high-concentration gas through adsorption-desorption and concentration. RTO (760°C), RCO (300–550°C) and CO (300–550°C) combustion technologies oxidize and decompose VOCs into harmless CO₂ and H₂O. |
| Acidic/Alkaline Exhaust | Scrubber tower | Purify waste gas via acid-base neutralization reaction. The purification efficiency of sulfuric acid mist, hydrochloric acid mist and hydrofluoric acid mist ≥95%; the removal rate of chromic acid and cyanide ≥90%. Equipped with an anti-corrosion structure for long-term stable operation. |
| Special Exhaust (NOx) | NOx treatment system | Combined process of NO oxidation tower and NO₂ reduction tower, with NaOH and reducing agent dosing. The overall NOx removal rate is over 95%, which completely eliminates yellow smoke at the chimney outlet. |
| Special Exhaust (AsH₃, PH₃) | Metal oxide adsorption | Adopt chemical absorption principle. Active adsorbent components (e.g. CuO) undergo irreversible chemical reactions with toxic gases, converting harmful pollutants into harmless solid compounds such as Cu₃As₂ and Cu₃P₂. |
| Special Exhaust (NF₃, SiH₄, etc.) | Thermal Plasma | Adopt internationally advanced thermal plasma + wet scrubbing combined technology. Pollutants are pyrolyzed and decomposed under ultra-high temperature (up to 3,000°C). Equipped with independent cooling and scrubbing sections for dual filtration and purification. |
| Dust, acid mist, aerosols | Wet electrostatic precipitator (EP) | The dust removal efficiency is over 99%. Featuring low pressure drop and low energy consumption, it is specially designed for fine particulate matter and mist pollutants. |
| Process exhaust ducts | Process exhaust system | Adopt FRP duct material, featuring light weight, high strength and excellent chemical corrosion resistance. Suitable for the transportation of acid & alkaline exhaust, flue gas and dust-containing waste gas. |
