Experience in the application of injectors for desulfurization of coke oven gas

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With the development of desulfurization technology and the application of new processes and equipment, more and more enterprises are adopting the ejector regeneration process for desulfurization regeneration. The injector is one of the key devices in the jet regeneration process. The ejector is composed of a liquid inlet, an air inlet, a liquid inlet pipe, a nozzle, an air chamber, a throat, a diffuser tube, and a tail pipe. When the inlet pressure is generally 0.4–0.5 Ma, the flow velocity at the nozzle is 18–25 m/s, and the liquid discharge volume of the ejector depends on the size of the nozzle. When the pressure at the liquid inlet is constant, the suction volume of the ejector is determined by the liquid injection volume. https://pic1.zhimg.com/80/v2-1c423e2ea756a46044fa00d635955e28_720w.webp The desulfurized solution (rich liquid) is pumped to the inlet of the injector via the desulfurization liquid pump; the desulfurization liquid then flows straight down from the throat of the injector. Due to the high-speed ejection of the solution at the throat, a certain negative pressure is created in the ejector’s gas chamber; as a result, external air enters the gas chamber under the effect of this pressure difference and enters the throat along with the solution. Air and the solution mix thoroughly in the throat, allowing the catalyst in the solution to rapidly and fully absorb the oxygen from the air and be oxidized to complete regeneration. The resulting sulfur particles are floated and overflowed in the regeneration tank, thereby completing the conversion of the desulfurization liquid from a rich liquid to a lean liquid. According to theoretical calculations, 1.57 standard cubic meters of air are required to absorb 1 kilogram of hydrogen sulfide. In wet flue gas desulfurization processes, injectors are used for the regeneration and oxidation of the solution, and the amount of air needed for this purpose is approximately 10–15 times the theoretical amount. In addition to the air required for regeneration and oxidation, factors such as sulfur foam flotation also need to be taken into account. During the operation of the ejector, especially after prolonged use, sulfur paste or crystals will adhere to the inner walls of the ejector to varying degrees. This increases the resistance to the flow of the regeneration liquid, reduces the amount of air that can be drawn in, and causes backflow at the inlet. As a result, the regeneration efficiency of the solution is reduced, and the quality of the foam in the desulfurization regeneration tank declines. In severe cases, this leads to a decrease in desulfurization efficiency and even tower blockage. Therefore, it is essential to pay attention to the use and maintenance of injectors, as well as to conduct regular inspections to ensure they perform optimally. When it is determined that the injector is severely clogged, it is first necessary to determine, based on the properties of the desulfurization liquid and experience, whether the blockage in the injector consists of sulfur or salt crystals. During the treatment process, the inlet valve of the problematic injector can be closed first, and the injector can be flushed with steam or water (depending on the type of blockage). If the cleaning effect is not satisfactory, it is necessary to remove the short section in front of the nozzle, take off the nozzle itself, and clean it using tools or a high-pressure water gun. After that, it should be reinstalled. It is important to note that it is best to mark the positions of the bolts before removing the nozzle; when reinstalling the nozzle after cleaning, it must be aligned properly, with each nozzle corresponding to its proper position.