Many harmful gases are generated during petrochemical and natural gas processing, among them sulfur-containing gases (such as H₂S) that cause serious air pollution and require treatment with sulfur recovery devices. In the sulfur recovery process, the burner is a core piece of equipment; its function is to convert acidic gases such as hydrogen sulfide into sulfur while controlling pollutant emissions. By precisely controlling the combustion process, sulfur burners can achieve efficient sulfur recovery and pollutant purification. The design of sulfur burners, which needs to balance thermal efficiency, emission compliance, and operational stability, is a crucial aspect of industrial waste gas treatment.
The sulphur burner design is directly affected by the level of the burner manufacturer. The quality of the burner design will directly affect the stability of the burner, reaction efficiency, furnace temperature distribution and sulfur recovery rate during the sulfur recovery process. To achieve both sulfur recovery and environmental compliance, the design of industrial burners in SRU systems must meet conditions such as high temperature, corrosive gases, and complex combustion. Therefore, the structural design of sulfur burners is particularly critical.
Harsh Operating Conditions for Sulphur Burners
High-temperature and high-pressure combustion environment
During combustion in the SRU unit, the thermal reactor temperature is typically maintained at 980-1400℃ to ensure that H₂S is fully oxidized to SO₂ and to maintain reaction stability. During this period, the operating pressure is generally maintained between 20 and 100 kPa, depending on the number of downstream converter stages and whether an exhaust gas treatment unit is installed.
Highly corrosive atmosphere
The combustion products contain components such as H₂S, SO₂, SO₃, H₂O, H₂, CO, COS, and CS₂. Among them, SO₃ combines with water vapor to form sulfuric acid, which can easily cause equipment corrosion and sulfur buildup.
Toxic media present
The raw material gas contains a high concentration of hydrogen sulfide, which is a highly toxic gas. There is a high risk of leakage, posing stringent requirements for equipment sealing and operational safety.
Complex combustion conditions
Combustion takes place in a reducing atmosphere, requiring precise control of the air-to-acid gas ratio to avoid excessive oxygen, generating SO₃, which would lead to corrosion and a decrease in sulfur recovery rate.
In summary, the working environment of sulfur recovery unit burners is characterized by high temperature, high pressure, strong corrosion, and high toxicity, requiring precise control. The burners must have good adaptability, which places extremely high demands on the burner design materials, control system, and operation and maintenance of sulfur burners.
Key Considerations for Sulphur Burner Design in Sulfur Recovery Units
1. Flame Stabilization Design
Combustion stability is a critical indicator in burner design, directly impacting combustion efficiency, emissions performance, and equipment lifespan. Unstable combustion can lead to flameout, reduced combustion efficiency, increased pollutant emissions, and equipment damage. To achieve stable and reliable combustion, industrial sulfur burners are typically designed with various flame stabilization technologies. The most common designs include swirl structures, flame stabilization devices, and staged combustion systems.
Swirl design
The swirl design is a common flame stabilization design in SRU burners. Its core working principle is to use a swirler to rotate the secondary air, creating a high-temperature flue gas recirculation zone that enhances the ignition and stable combustion of the pulverized coal gas flow. This recirculation zone can bring some of the high-temperature combustion products back to the flame root, providing a continuous ignition heat source for newly entering fuel gas, thus effectively maintaining flame stability. The swirl design also improves fuel-air mixing, resulting in more complete combustion and improved flame morphology and temperature distribution.
Flame holder
A flame holder guides airflow through a specially designed rotating channel. When combustion gas mixes with air, the spiral pattern on the disc surface generates centrifugal force, causing the mixture to form a rotating flame ring. This design keeps the flame root in an ideal position, preventing flame detachment or backfire. Experimental data shows that a properly designed flame holder can improve combustion efficiency by approximately 25%.
The flame stabilization device is also a master of temperature regulation. Its special material has heat storage properties, and it can quickly release the stored heat to maintain stability when the flame fluctuates. The thickness of the disc is precisely calculated; too thin and it will result in insufficient heat storage, while too thick and it will affect the response speed. The optimal thickness range is usually 3-5mm. Within this range, the flame stabilization disc can quickly conduct heat while maintaining sufficient thermal inertia to buffer fluctuations.
Staged combustion
Staged combustion technology introduces air or fuel into the combustion zone in stages to achieve a more stable and controllable combustion process. Typically, SRU burners incorporate different air passages, such as primary and secondary air systems. This design not only improves combustion stability but also effectively controls combustion temperature and oxygen distribution, thereby increasing the efficiency of H₂S partial oxidation and reducing incomplete combustion.
2. High Temperature Resistance Structural Design
The thermal reactors in sulfur recovery units typically operate in extremely high-temperature environments, with furnace temperatures often reaching 1000°C to 1400°C. Under such operating conditions, due to prolonged contact with high-temperature flue gas, the materials and structure of the SRU burner need to possess excellent heat resistance and stability. If the burner material cannot withstand the high-temperature environment, structural deformation, material fatigue, and even equipment lubrication problems may occur. Therefore, high-temperature-resistant structural design is a very important consideration when designing industrial sulfur burners.
Selection of high-temperature resistant materials
To cope with high-temperature operating conditions, SEU burners mostly use high-temperature resistant alloy steels such as Cr25Ni20 and 12Cr1MoV. These materials can maintain high mechanical strength and oxidation resistance in environments above 1000℃, avoiding deformation or corrosion at high temperatures. Meanwhile, the surface of the components will undergo treatments such as aluminizing and ceramic spraying to enhance their resistance to flue gas erosion and slagging.
Cooling structure design
Under certain high-load conditions, burners may employ cooling structure designs. These mainly include air cooling, water cooling structures, and double-layer structures. These designs can effectively reduce the operating temperature of critical components, thereby extending the service life of the equipment.
3. Corrosion-Resistant Design
The corrosion of sulfur burners by high-temperature flue gas mainly includes three types: acid gas corrosion, high-temperature oxidation corrosion, and condensation corrosion. To address these three types of corrosion, a common anti-corrosion design involves applying anti-corrosion coatings to the flue gas. Examples include high-nickel alloys, sulfur-resistant alloys, and special corrosion-resistant coatings. These materials effectively resist acid gas and high-temperature corrosion.
Through these design optimizations, industrial burners can maintain stable operation under complex conditions, thereby improving the overall operating efficiency and reliability of sulfur recovery units.
In practical engineering applications, choosing an industrial burner manufacturer with extensive experience is particularly important. Ruichang focuses on providing a variety of industrial combustion solutions, including SRU burners. Professional manufacturers can provide customized design solutions based on the scale of the unit, gas composition, and process conditions, thereby ensuring the long-term stable operation of the sulfur recovery unit and achieving higher sulfur recovery efficiency.
