In the petrochemical and refining industries, sulfur-containing gases primarily originate from FCC units, delayed coking, and hydrodesulfurization processes during crude oil processing. These gases, including hydrogen sulfide, mercaptans, and sulfur dioxide, can lead to acid rain formation and air pollution if left untreated. According to recent studies, global sulfur emissions have risen from low levels in 1750 to a peak in 2022, mainly due to industrialization. The necessity of treating these gases lies in protecting ecosystems and preventing soil acidification and water pollution. In China, in cities like Beijing and Shanghai, factory emissions directly impact air quality, leading to respiratory illnesses.
The history of sulfur-containing gases can be traced back to the Industrial Revolution, when coal burning caused the London smog incidents, prompting the earliest air pollution regulations. Today, with updated environmental regulations in 2025, treating sulfur-containing gases has become central to corporate compliance. Yuchang Environmental’s RTO system uses high-temperature oxidation to convert H2S into SO2, which is then neutralized through scrubbing, achieving efficient removal.
SOₓ exhaust gas (sulfur oxide exhaust gas) refers to industrial or combustion emissions containing sulfur oxides, primarily sulfur dioxide (SO₂) and a small amount of sulfur trioxide (SO₃). In environmental engineering and air pollution control, SOₓ is commonly used as a general term for these pollutants.
SO₂ is oxidized to SO₃ in the atmosphere, which then reacts with water to form sulfuric acid (H₂SO₄). Acid rain corrodes buildings, acidifies soil and water bodies, and damages ecosystems.
It irritates the respiratory tract, triggering coughs, asthma, and bronchitis; the sulfates formed by combining with particulate matter can penetrate deep into the alveoli, increasing the risk of cardiovascular disease.
SO₂ and sulfuric acid mist are highly corrosive to metal pipes, boilers, chimneys, electronic equipment, etc., shortening their lifespan.
Sulfate aerosols are an important component of fine particulate matter (PM2.5) in the atmosphere, reducing atmospheric visibility (smog); They have a cooling effect (reflecting solar radiation)
| Major Sources of SOx | Components of SOx | Special Characteristics |
|---|---|---|
| Fossil Fuel CombustionPower plants, industrial boilers using coal or oil | Sulfur Dioxide (SO2)The predominant component | Acid Rain Precursor: Reacts with water vapor to form sulfuric acid (H2SO4), causing damage to forests, aquatic life, and building materials. |
| Procesos industrialesSmelting of mineral ores containing sulfur, oil refining | Sulfur Trioxide (SO3)Usually forms secondary to SO2 | Respiratory Toxicity: Highly irritating to the respiratory system; triggers bronchoconstriction and asthma attacks even at low concentrations. |
| TransporteLocomotives, ships, and heavy equipment using high-sulfur diesel | Sulfate Particles (SO42-)Particulate form | PM2.5 Formation: Contributes significantly to the formation of fine particulate matter (secondary aerosols), reducing visibility and harming lung health. |
| Natural SourcesVolcanic eruptions, sea spray, biological decay in wetlands | Trace Sulfur Species | Cooling Effect: Sulfate aerosols can reflect sunlight (albedo effect), potentially causing a temporary local or global cooling effect on the climate. |
Integrated Workflow: Thermal Oxidation (DeVOC) + Wet Scrubbing (DeSOx)
| Category | Parámetro | Value / Specification | Technical Note |
| 1. Core Performance | Eficiencia de eliminación | > 99% | For both SOx and VOCs |
| Thermal Recovery | 95% - 97% | Saves approx. 80% fuel | |
| Oxidation Temp | 850 - 950°C | High temp ensures full S-conversion | |
| Tiempo de residencia | 1 - 2 Seconds | Ensures complete oxidation reaction | |
| Airflow Range | 10,000 - 500,000 m³/h | Scalable capacity | |
| Caída de presión | < 200 Pa | Low resistance design | |
| Turndown Ratio | 5 : 1 | Flexibility for load fluctuation | |
| System Availability | 99% | High uptime reliability | |
| 2. Emission & Input | Inlet Sulfur Conc. | 5,000 ppm H₂S | High sulfur tolerance |
| Outlet SOx | < 50 mg/Nm³ | Compliant with strict regulations | |
| Outlet NOx | < 100 mg/Nm³ | Low NOx burner technology | |
| Control de partículas | Pre-filter System | Prevents media clogging | |
| Humidity Control | Pre-drying | Reduces moisture burden | |
| LEL Control Limit | < 25% | Lower Explosive Limit safety margin | |
| Outlet Temp | 150 - 200°C | Safe discharge temperature | |
| 3. Design & Material | Construction Material | Hastelloy C-276 | Critical: Anti-corrosion against H₂SO₄ |
| Intercambiador de calor | Structured Ceramic | High thermal mass media | |
| Surface Area | 500 - 800 m²/m³ | Specific surface area for heat transfer | |
| Chamber Volume | 0.5 - 1 m³ | Per 1,000 m³/h airflow | |
| Valve Switching | 60 - 120 Seconds | Optimized cycle time | |
| Valve Cycle Life | > 1 Million Cycles | High durability switching valves | |
| Leakage Rate | < 0.1% | Poppet valve sealing technology | |
| System Footprint | 10 - 50 m² | Compact design | |
| 4. Integration & Utility | Post-Treatment | DeSOx Scrubber | Critical: Removes SO₂ formed in RTO |
| Tipo de combustible | Natural Gas | Low NOx burners utilized | |
| Consumo de energía | 0.5 - 1 kWh/m³ | Low electrical demand | |
| Bake-out Temp | 500°C | Self-cleaning mode for media | |
| Preheat Temp | 200°C | Inlet waste heat utilization | |
| OPEX Savings | 40% | Compared to standard thermal oxidizers | |
| 5. Control & Safety | Automation | PLC + AI Maint. | Smart predictive maintenance |
| Escucha | Sistemas de gestión de la calidad del aire (CEMS) | Continuous Emission Monitoring System | |
| Safety Device | Flame Arrestor | Explosion prevention at inlet |
Hastelloy coating, lifespan 5-10 years; seals are consumables and need to be replaced annually.
High-alumina, acid-resistant; replaced every 5-7 years.
Low NOx; nozzles are consumables and require quarterly inspection.
Drive belt, easily worn and replaced every 2 years.
LEL temperature sensors, consumables requiring calibration every six months.
Plastic rings, replaced every 3 years due to fouling.
→ RTO + Sulfur-resistant design, 99% SOx removal rate, stable operation throughout the year, passed the ultra-low emission acceptance test in the Beijing-Tianjin-Hebei region.
→ Seamless integration of RTO and FGD (flue gas desulfurization), fully compliant with Japan’s Air Pollution Control Act, and noise controlled below 65 dB – the neighbors thought we were just running air conditioners.
→ Customized two-stage oxidation + rapid cooling + adsorption post-treatment, outlet H₂S <10 ppm, employees can finally smoke near the exhaust port (although we don’t encourage it).
Editor: Miya