Sealing Performance Of Fishbone Gasket On Flange Of BJS1100 Heat Exchanger

With the enlargement of heat exchangers,the increase of working temperature,working pressure and environmental protection requirements,the commonly used sealing gaskets have been unable to meet the sealing requirements.As a new type of gasket,Fishbone gasket is being applied to the flange seal of high temperature and high pressure heat exchanger.It has many advantages such as strong pressure bearing capacity,self-sealing characteristics and multi-channel sealing capability.Therefore,the paper studies the sealing performance of fish bone gasket on BJS1100 heat exchanger.Firstly,the sealing characteristics of the Fishbone gasket were studied.The orthogonal test was designed based on the parameters such as tooth thick Ness,pitch and tooth height of the Fishbone gasket.The numerical simulation was carried out by ANSYS software to optimize the parameters.After the parameter optimization,the compression ratio and rebound rate of the metal skeleton of the gasket are effectively improved on the original basis.Secondly,the physical gasket is processed by the optimized gasket parameters and the compression back elastic energy and the normal temperature sealing test at different temperatures are carried out.The test results show that the gasket reinforcement ring and the flange compaction when the gasket stress reaches about 40MPa;under the same assembly stress,the compression amount increases with the increase of temperature,and the rebound amount decreases with the increase of temperature.Seal test data indicates that after the gasket reinforcement ring and flange are compacted,the leakage rate is basically maintained in the range of 0.064-0.122×10^-3cm³/s,and the tightness reaches the T₃（compact）level;when the assembly stress is gradually unloaded,the metal skeleton of the gasket and the outside The reinforcing ring can compensate for a certain stress loss,so the gasket leakage rate remains stable when the gasket assembly stress is reduced,but the leakage rate increases and the tightness decreases to the T₂（standard type）level when the assembly stress drops to 15 MPa.Finally,the finite element model of BJS1100 flange connection system was established by ANSYS finite element analysis software.The room temperature assembly,room temperature pressure,steady temperature field,thermal-structure coupling field and transient work of the Fishbone gasket flange connection system were analyzed.Conditional sealing performance.The results show that the axial compressive stress of the fishbone gasket gradually increases from the inside to the outside in the radial direction and is evenly distributed along the circumference.The gasket maintains good sealing performance when the bolt preload is reduced by 40KN.In the thermal-structural coupling field,the innermost node stress of the five nodes distributed along the radial direction is reduced to 10 MPa,but the stress at the two nodes outside the gasket is still higher than 40 MPa.Under three transient conditions,the stress of the Fishbone gasket is small,which can adapt to the various working conditions of the heat exchanger.