An elbow with internal spiral fins near the wall

Abstract

The purpose of the present invention is to provide an elbow with inner spiral fins near the wall, which is suitable for the transportation of gas-liquid two-phase fluids and fluids containing volatile media, and eliminates the change of the flow direction of the elbow and the change of the wall surface of the pipeline. The boundary layer separation and secondary eddy current caused by the uncoordinated inner and outer curvatures reduce the corrosion degree of the inner and outer walls of the elbow and improve the service life of the fluid conveying pipeline. The technical scheme adopted in the present invention is as follows: an elbow with inner spiral fins on the near wall surface, comprising an elbow body, an inlet nozzle flange and an outlet nozzle flange at both ends of the elbow body, 2 to 6 groups of Inner helical fins, the inner helical fins extend along the inner wall of the elbow pipe from the inlet to the outlet inside the elbow, the inner helical fins are variable pitch fins, and the pitch decreases first along the flow direction increasing trend later.

Description

technical field [0001] The invention belongs to the technical field of pipeline anticorrosion, and in particular relates to an elbow with internal spiral fins on the near wall surface of a fluid delivery pipeline for realizing corrosion reduction. Background technique [0002] Pipelines are the key equipment for the oil refining and chemical industry to realize fluid transportation, connect various processes, and ensure the normal operation of the process; in the process of oil refining and chemical production, there are many types of fluids transported by pipelines, which can be divided into pure gas phase, pure Liquid phase, gas-liquid two-phase and gas-solid two-phase. At present, when transporting gas-liquid two-phase or pure liquid phase fluid containing volatile components, the fluid flows through the position of the pipe elbow. Due to the incoordination of the inner and outer curvatures of the pipe elbow, the fluid is on the inner and outer walls of the elbow. In par...

AI Technical Summary

Problems solved by technology

At present, when transporting gas-liquid two-phase or pure liquid phase fluid containing volatile components, the fluid flows through the position of the pipe elbow. Due to the incoordination of the inner and outer curvatures of the pipe elbow, the fluid is on the inner and outer walls of the elbow. In particular, boundary layer separation occurs on the inner wall near the outlet, and secondary eddy currents are generated due to the uneven pressure on the inner and outer walls. These two phenomena lead to serious cavitation corrosion on the inner wall of the elbow near the outlet; therefore It is of great significance to improve the corrosion characteristics of the elbow and to increase the life of the pipe.

[0003] There are many measures to reduce pipeline corrosion, including adding corrosion inhibitors, coating protection, changing pipeline materials, and cathodic protection. It is proposed that it has little effect on reducing the corrosion caused by boundary layer separation and secondary vortex caused by the reverse flow change of the elbow and the incoordination of the inner and outer curvature of the pipe wall; the existing literature (patent number: ZL201410155224.X) Also proposed a pipeline damping device to reduce vibration and cavitation, which mainly uses a set of spiral guide tubes with variable lift angles and double-sided spiral guide tubes with variable lift angles to generate swirling flow to reduce pipeline vibration and eliminate cavitation, but the structure of this pipeline damping device is relatively complicated, and it is not suitable for the elbow structure. However, the existing documents (patent number: ZL201710392415.1, patent number: ZL201520040984.6) respectively propose a The inlet fluid spiral guide energy-saving device, the compressor exhaust pipe that relies on the spiral guide part to improve the oil-gas separation efficiency, and the compressor with this exhaust pipe, but the flow resistance loss of these two devices is relatively large, and they do not have Variable cross-section diversion

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