High-efficiency sulfur spray gun adopts two-stage mechanical fixed multi-channel atomization technology, atomizing particle size is less than 20μ m, improve the atomization efficiency and anti-clogging ability of the nozzle. The single gun flow rate can be adjusted in the range of 4.6~ 10.5t /h, and the atomization working pressure is controlled in the range of 0.4~ 1.0MPa, which can still atomize efficiently, reducing the pressure in the liquid sulfur pipeline.

High efficiency nozzle

High efficiency nozzle adopts fixed mechanical forced screw atomization and Laval nozzle growth technology. The liquid sulfur enters the nozzle from the liquid sulfur tube, accelerates through the primary Laval nozzle, enters the mechanical forced spiral atomization core, forms a high-speed centrifugal rotation body, enters the secondary Laval nozzle again, and is accelerated again. At this time, the emitted liquid sulfur obtains high-speed centrifugal force and acceleration, making it form atomized sulfur particles less than 20um. Under the action of Laval nozzle technology, the atomization pressure of liquid sulfur is reduced to 0.4MPa, and the efficient atomization effect is achieved.

The nozzle is sealed with thread line, which realizes that there will be no liquid sulfur leakage in 800 ℃ high temperature cold and heat shock. In order to reduce the probability of weld leakage in the sulfur burning furnace, there is only one weld in the gun body through clever design, and through the stress relief design, the weld can be effectively prevented from tearing due to stress concentration. The finite element stress analysis of the weld of the steam insulation sleeve can be seen that the stress at the weld of the steam insulation sleeve is very low

In order to solve the problem that the nozzle sealing surface is damaged by thermal radiation due to the shutdown of the device, the sealing surface is moved back to the steam cooling place of the insulation jacket, which can effectively reduce the temperature of the nozzle sealing surface. Even if the device is stopped for 8 hours, the temperature of the sealing surface can be maintained below 200 ℃. The nozzle gasket is made of graphite composite gasket resistant to high temperature of 800 ℃.

Gun body structure

After analysis, the main cause of bending sulfur spray gun is uneven distribution of thermal stress on the gun body. The change of thermal stress of the gun body was analyzed in the design of the high efficiency sulfur spray gun thermal jacket. When the device is running, the combustion flame is affected by the airflow vortex, and the flame will heat the front of the sulfur spray gun, and the front area is baked by the flame, so the front of the spray gun will have thermal stress expansion. In order to make the thermal stress expansion of the gun consistent, it is necessary to distribute the heat insulation steam evenly inside the gun body. Therefore, we set four uniform distribution rings of heat insulation steam on the circulation area of the gun jacket (see the upper left figure), and use the uniform distribution ring to forcibly mix the steam temperature of each section, so that the steam temperature entering the next section is consistent. Thus, the gun body temperature is consistent to avoid thermal stress expansion of the gun body.

In order to reduce the risk of leakage of the gun body, through the finite element expansion analysis of the thermal expansion of the gun body, the inner clip sleeve is supported by sliding compensation (see the upper right figure), which can be designed to the outside of the sulfur burning furnace, and can also achieve effective expansion compensation for the gun body, thereby eliminating the risk of corrosion and leakage of the weak link of the gun body.

Traditional and efficient before and after comparison

Application of traditional sulfur spray gun

The customer is a large chemical enterprise, there are two sets of 400 kt/a sulfur acid production equipment, sulfur burning furnace are horizontal arrangement, the shell is steel cylinder lined with firebrick and insulation materials, two retaining walls are set in the furnace, air through the spiral plate from the sulfur spray gun around the sulfur burning furnace in a turbulent flow. Each sulfur burner adopts two mechanical fixed atomizing sulfur spray guns with 200kt /a standard production capacity. The length of the spray gun is 2 650 mm, the diameter of the atomizing nozzle is 12 mm, and the flange gland is used to seal. When the traditional spray gun atomizes the liquid sulfur, the sulfur drops on the bottom of the sulfur burner, resulting in the high operating temperature of the sulfur burner, and often there are gun body deformation, nozzle insulation steam leakage, nozzle blockage and other failures, resulting in production.

Liquid sulfur in the absence of atomization state, the average free burning speed of 15.6 kg/(m2· h). When there is liquid sulfur burning at the bottom of the furnace, the operating temperature will be extremely high. In order to avoid the volume expansion of the furnace due to rising temperature, the internal stress will cause the furnace to deform, or the masonry will be crushed and arch, expansion joints will be left when the furnace is built. In the design, a 20 mm expansion joint is left between the furnace wall of the furnace barrel, the front wall and the back end wall. The retaining wall is built into the inner layer of firebrick, and there are expansion joints on both sides of each retaining wall, and several 10 mm expansion joints are also set up during masonry to ensure the total expansion amount. The flowing liquid sulfur will flow through the expansion joints at the bottom into the insulation and slowly burn. The operating temperature of the steel shell of the sulfur burning furnace is generally about 45 ℃, because the heat of the sulfur burning between the insulation layer and the steel shell can not be transferred to the furnace, but can only be transferred to the environment, resulting in the actual temperature of the steel shell of the sulfur burning furnace to reach 150~170 ℃, SO2 reacts with oxygen under the catalysis of iron to produce SO3, which corrodes the weld seam of the steel shell. Due to the lack of air between the steel shell and the insulation layer, the liquid sulfur burns slowly, and the unburned sulfur flows out of the corrosion hole in the form of sublimed sulfur, forming sulfur stalactite under the sulfur burning furnace.

Application of high efficiency sulfur spray gun

In order to effectively solve the above problems, the customer replaced the traditional sulfur spray gun with a high-efficiency sulfur spray gun, and the operation indicators of the sulfur burner reached the design value, improved the production capacity of the device, and effectively guaranteed the long-term safe operation of the sulfur acid production device.                            

In the six months after the operation, there was no leakage of the nozzle front flange sealing surface during the temporary parking of the device. The high-efficiency sulfur spray gun can effectively adapt to the load of the device at 60%~110%, and there is no liquid sulfur burning at the bottom of the sulfur burning furnace within the load range (see figure 1 on the upper right). The steam jacket leakage due to alternating hot and cold was solved, and the situation that the atomization flow rate decreased and sulfur stalactite appeared in the lower part of the sulfur burning furnace did not occur during operation. The working flow range of the high-efficiency sulfur spray gun is larger, the maximum flow rate is increased by 0.49 t/h, and the minimum flow rate is reduced by 1.36 t/h. The working pressure is reduced by about 0.3MPa; The atomization distance is shortened by about 1 m. The operating temperature inside the furnace is reduced by 160 ° C, and the surface temperature is reduced by 72~90 ° C to ensure that the furnace operates at a safe temperature. The application of the high-efficiency sulfur spray gun optimizes the atomization effect of liquid sulfur (see Figure 3 on the upper right), increases the maximum load and sulfuric acid capacity of the sulfur acid making unit, and can increase sulfuric acid production by 120 t per day. After the high-efficiency sulfur spray gun was put into use for nearly half a year, the sulfuric acid production capacity increased by 16 500 t and the productive steam 23 100 t, creating revenue of 21 million yuan for the enterprise and significant economic benefits. Due to the decrease in the operating pressure of the sulfur gun and the decrease in the acid flue gas. (SO2) increase, tons of acid power consumption can save 2.8 kWh/t, played a role in energy saving and consumption reduction.                              

Conclusion

The production practice has proved that the structural design and material selection of the high-efficiency sulfur spray gun are more reasonable, which can meet the working environment in the sulfur burner. Replacing the traditional sulfur spray gun with the high-efficiency sulfur spray gun completely solves the problems of high operating temperature of the sulfur burner, the deformation of the spray gun body, the leakage of the nozzle insulation steam pipe sleeve, the blockage of the liquid sulfur pipeline insulation steam pipe sleeve, and the low production capacity of the device. The production capacity and steam output of the sulfur acid making unit are improved, the energy saving effect and economic benefits are significant, and the long-term safe and stable operation of the unit is guaranteed, which is worth popularizing and applying.