Study On Influence Law Of Wear And Corrosion In Hydrogen Fluoride Pre-reactor

Fluorine chemical industry is one of the cornerstones of China’s high-quality economic development,which has become an important part of the national strategic emerging industries.Whta’s more,Fluorine chemical industry also provides material guarantee for both the development of other strategic emerging industries and the improvenment of traditional industries.Thus,it plays a very important role in promoting China’s manufacturing industry structure adjustment and product upgrading.Hydrofluoric acid is the source of fluorine in many fluorine chemical products.Its raw materials and products are highly corrosive.And corrosion failure of production equipment often occurs,resulting in personnel or economic losses.Hydrogen fluoride pre-reactor is a part which most likely to fail.The production of hydrogen fluoride by high viscosity and strong corrosive slurry in its internal spiral propulsion process leads to wear and corrosion.In this study,the influence of wear and corrosion in hydrogen fluoride pre-reactor was studied,and the corrosion of high viscosity and strong corrosive slurry was researched under different rotating speeds and powder-acid ratio(mass ratio of powder to sulfuric acid).The main research contents and conclusions are as follows:The influence of wear and corrosion on fluorine chemical pre-reactor was studied by combining experiment and numerical simulation.Firstly,the wear and corrosion test bed of hydrogen fluoride pre-reactor was designed and built,and corrosion test specimens were set up inside.The wear and corrosion rate of screw shaft and paddle was measured by weight loss method and electrochemical method under operating condition.At the same time,the corresponding static corrosion test was carried out.The corrosion morphology of specimens was observed by optical microscope.Then,the dynamic corrosion rate and static corrosion rate of the specimens were compared and analyzed,and the influence of rotation parameters on the wear corrosion was obtained.Finally,CFD numerical simulation software was used to study the flow field inside the testing machine under different experimental conditions,which was used to assist in the analysis of the influence law of internal wear and corrosion.The findings of this study include the following ones: the wear and corrosion rate in fluorine chemical pre-reactor increases with the increase of rotating speed,and it first increases and then decreases with the increase of powder-acid ratio.The wear and corrosion rate of paddle is greater than that of screw shaft.The wear and corrosion rate at the inlet is the highest due to the larger impact.In this study,the influence of dynamic wear caused by rotation on the corrosion rate of the reactor has a certain proportion: about35%-68% in the case of thin slurry and 15%-60% in the case of thick slurry.The flow field inside the testing machine was obtained by numerical simulation.It was found that the height of slurry in the testing machine decreased gradually from the entrance to the exit.The flow velocity distribution of slurry in different sections in the testing machine is quite different,and the turbulent characteristics of the inlet fluid are obvious.With the increase of the flow distance,the flow tends to laminar flow state.The wall shear stress of rotating parts increases with the increase of rotating speed and powder-acid ratio,and the maximum shear stress is at the paddle edge.The average wall shear stress increases linearly with the increase of rotational speed and s-shaped with the increase of powderacid ratio.The simulated wall shear stress distribution is close to the experimentally obtained wear and corrosion rate distribution.