The Investigation On Sealing Performance Of Bolted Flanged Connections In Slurry Oil Steam Generator At Elevated Temperature

Slurry oil steam generator is important heat exchanger in fractionation system of catalytic cracking unit. Deoxidized water in the shell side is heated by oil slurry in the tube side to producing vapor in slurry oil steam generator. Sealing performance of bolted flanged connections in slurry oil steam generator is remarkably affected by temperature and pressure, especially under variable temperature and pressure condition, and easily leads to fluid leakage. Thus, it is important theoretic significance and great practicality worth to study sealing performance of bolted flanged connections in slurry oil steam generator at elevated temperature.The pipe box bolted flanged connections in slurry oil steam generator were researched basing on the FEA software ANSYS. Temperature field, stress field and coupling field of bolted flanged connections were analyzed at four working conditions including high temperature, bolt preload, internal pressure and operation condition. Sealing performance of bolted flanged connections under four working conditions, including steady high temperature, different bolt preload, different pressure difference between tube and shell side and thermal-structure coupling conditions was studied. The content is as follows:1 Based on equivalent solid plate theory, three-dimensional model of bolted flanged connections as an integrated whole was simplified and built.2 FEA model of bolted flanged connections was built based on heat transfer theory. Temperature field distribution of bolted flanged connections is achieved by steady temperature field analyzing whose result will be temperature load for thermal-structure coupling analysis.3 The thermal-structure coupling analysis method that temperature field result was imported into structure analysis was described. Given gasket material compression-resilience characteristic and contact nonlinear behavior, bolted flanged connections at three working conditions including bolt preload, internal pressure and operation condition were simulated basing on the FEA software ANSYS. Stress distributions of flange, bolt and gasket were obtained and sealing performance of bolted flanged connections was evaluated.4 Adding disc springs, bolted flanged connections under three working conditions including bolt preload, internal pressure and operation condition were simulated to obtain gasket stress distribution under three working conditions and study influence of disc spring on sealing performance. The results showed that influence of disc spring on gasket stress was small under bolt preload, internal pressure working conditions. Disc springs can effectively improve sealing performance of bolted flanged connections. Pipe and shell side gasket stress distribution were more even and were larger by adding disc springs under operation condition and disc springs can effectively improve sealing performance of bolted flanged connections.