Environmental Analysis of High Temperature Gear Pumps and Improvement of Mechanical Seals

Analysis of the use of high temperature gear pump environment High temperature gear pump for conveying solid particles and fibers, non-corrosive high temperature liquid medium temperature up to 250 ℃, viscosity of 5-1500 cst. When the gear rotates, the melt enters the tooth grooves of the two gears of the suction chamber. As the gear rotates, the melt is brought into the discharge cavity from both sides, and the gears mesh again to make the melt in the tooth grooves to be squeezed out Cavity, pressure delivery to the outlet pipe. As long as the pump shaft rotates, the gear presses the melt down to the outlet side. High-temperature gear pump for the delivery of polyester vinegar, booster equipment, high-temperature gear pump compact structure, the lucky antelope reliable, low energy consumption, high volumetric efficiency, small shear on the melt in the high viscosity, high pressure flow Stable, no pressure fluctuations in exports. Make it muddy in the production of polyester irreplaceable role. In spite of this, the problem of mechanical seal leakage has always been a "bottleneck" in the stable operation of high temperature gear pumps. First, the main structure of high-temperature gear pump shaft seal is used double-sided bellows mechanical seal Second, gear pump mechanical seal inadequate (1) Since the production of polyester is a continuous operation, the installation of mechanical seal process, the seal Liquid can not run, gear pump body temperature up to 31090 ℃, causing rapid wedge graphite wreath expansion. Sealant investment, the mechanical seal chamber temperature decreases, wedge ring contraction, which led to mechanical seal leakage. For those mechanical seals that have been replaced due to leakage, hydrostatic tests were conducted and the wedge rings between the moving ring and the hub were found to be the major contributors to failure of the mechanical seal. (2) This structure of the mechanical seal on the maintenance staff of the installation of high level. In the installation process is not easy to accurately locate, resulting in moving ring deflection, leading to mechanical seal leakage. Third, the structural improvement of gear pump mechanical seal Shrink ring deformation of the deformation of the mechanical seal of the gear pump is the main reason for the failure to eliminate the wedge ring with the sleeve integration, can achieve the purpose of leakage (see Figure 1 the second half) . Re-processing of the sleeve, directly on the boss sleeve flange welding metal corrugated sheet, and then inlaid moving ring. The axial and radial dimensions of the collar depend on the axial distance and radial dimensions of the stop ring. At the same time, in order to facilitate the disassembly of the components, an additional groove (the width of the groove is 3mm and the depth of 3mm) is arranged at the root of the sleeve, and a corresponding circlip is provided. Fourth, the improved mechanical seal gear pump to eliminate the main leakage point, before the improvement, the average mechanical seal life of about 8 months. After the improvement, the mechanical seal runs smoothly and the failure rate is obviously reduced.