Poor atomization of the sulfur gun leads to liquid sulfur dripping to the bottom of the sulfur incineration furnace and seeping into the insulation layer beneath the refractory bricks. As there is a 10-20mm layer of glass fiber felt between the insulation layer and the steel shell of the sulfur incineration furnace, the liquid sulfur accumulates at this location. During the operation of the sulfur incineration furnace, the liquid sulfur undergoes sulfidation corrosion on the steel shell in a high-temperature and oxygen-deficient environment, forming iron sulfide. After the formation of iron sulfide, its volume expands, causing local stress concentration on the steel shell and accelerating material fatigue cracking. At the same time, the poor thermal conductivity of the corrosion products hinders the heat dissipation of the steel shell, and the local temperature rise further aggravates the deterioration of the metal structure. Over long-term operation, the strength of the steel shell decreases, increasing the risk of leakage and even furnace collapse (Figure 1), which seriously threatens the safe and stable operation of the equipment. Moreover, the repeated accumulation and evaporation of liquid sulfur in the insulation layer is even more concerning. The insidious nature of sulfidation corrosion often makes the accumulation of damage difficult to detect ( Figures 2 and 3), and the hidden dangers are only exposed when a sudden leakage occurs. By then, the difficulty and safety risks of repair have significantly increased.

(Refer to Figure 1)

(Refer to Figure 2)

(Refer to Figure 3)

Due to the poor atomization effect of sulfur guns, the liquid sulfur is atomized unevenly and accumulates in the lower area of the refractory bricks at the bottom of the sulfur incineration furnace. When the unit is restarted after a short-term shutdown or major maintenance, the liquid sulfur in the insulation layer is rapidly vaporized upon heating, generating local high pressure, which may cause the refractory bricks to crack or the steel shell to deform. After the temperature rise is completed and the sulfur guns are replaced, air enters the sulfur incineration furnace and mixes with the sulfur vapor evaporated in the furnace, causing local explosion vibrations. This may trigger a flash explosion of the sulfur vapor-air mixture, resulting in severe vibration of the equipment and even structural damage. Such accidents have occurred frequently during the start-up of sulfuric acid plants over the years, more often manifested as smoldering inside the sulfur incineration furnace (Figures 4 and 5). Under high-temperature heat storage conditions, the sulfur vapor continuously oxidizes and releases heat, generating a large amount of sulfur dioxide gas. If it enters the fan or is discharged into the atmosphere through the drying tower, it will cause sulfur dioxide pollution. Since the sulfur vapor cannot be completely burned in the smoldering state, if a pre-tower fan is used, sulfur will be formed on the wire mesh demister in the drying tower, reducing the demisting efficiency and increasing the system resistance. In severe cases, it may cause fan surging. If a post-tower fan is used, the condensation of sulfur vapor may corrode the blades, accelerate equipment deterioration, and the formation of sulfur on the fan impeller will disrupt the dynamic balance of the impeller, causing increased vibration and even triggering interlock shutdown. The longer the smoldering lasts, the greater the accumulation of sulfur, and the more serious the threat to the safe operation of the equipment. During the smoldering process, sulfur vapor repeatedly condenses and oxidizes and burns on the inner wall of the sulfur incineration furnace and the surface of the refractory bricks, forming complex thermal stress cycles, thereby accelerating the cracking and spalling of the refractory materials. Especially during frequent start-stop cycles, temperature fluctuations will cause the gap between the steel shell and the refractory bricks to expand, further promoting the infiltration and retention of liquid sulfur.

(Refer to Figure 4)

(Refer to Figure 5)

Sulfur vapor condenses and precipitates on the surface of the wire mesh demister in the drying tower, forming fine sulfur crystals that gradually block the pore channels, resulting in a reduction of the effective flow area. As the operating time increases, the demisting efficiency continues to decline, the gas-liquid separation ability weakens, causing an increase in the amount of moisture and acid mist carried, further exacerbating the corrosion of subsequent equipment. Eventually, the wire mesh demister fails, causing the water content in the system to exceed the standard, and subsequently leading to an increase in the amount of condensed acid in the system, ultimately causing corrosion and perforation of the tube bundles in the heat exchange equipment (Refer to Figure 6).

(Refer to Figure 6)

The sulfide gun, as a crucial and precise component in the sulfuric acid plant, although small in size, plays a decisive role in the safe and stable operation of the sulfur burner system. Poor atomization effect will trigger a systemic chain reaction, manifested as the burning through of the sulfur burner furnace body, abnormal vibration of the induced draft fan, explosion in the furnace, and corrosion of the wire mesh desulfurizer, among other serious accidents. This often overlooked core component may bring immeasurable safety hazards to the entire system, causing millions of dollars in economic losses in a single incident and directly threatening the lives of operators. Therefore, enhancing the priority of sulfide gun management has become a core link in ensuring the long-term safe operation of the sulfuric acid plant. It is recommended to establish a full life cycle management mechanism and implement standardized management throughout the process from selection verification, installation calibration, online monitoring to maintenance and replacement: conduct regular detection of atomization particle size and structural integrity inspection, focus on checking early abnormalities such as blockage and coking, sulfur droplet leakage, gun body bending, and combustion traces; when replacing, prioritize the use of high-temperature corrosion-resistant alloy materials to ensure precise matching with the high-temperature and high-pressure working conditions of the sulfur burner; simultaneously, strengthen the training of operators and standardize the parameter adjustment procedures during the start-up, shutdown, and load variation processes, to avoid the risk of atomization failure caused by improper operation from the source.

The next issue will focus on the extent of damage caused by poor sulfide gun atomization to multiple system units.