Study On Temperature Field And Sealing Performance Of Bolted Flange Connection System At High Temperature

The change of sealing performance and energy efficiency is the key factor to determine whether the bolted flange connection should insulated at high temperature or not.In view of the above problems,the experimental installation of bolted flange connection system under the high temperature was seted up at first by using the WN100-100 RF flange.And the highest temperature of it is 500℃.With this device,the flange joint without heat preservation under the condition of no wind,the speed of wind is 3m/s and insulated flange joint were carried out at 200 ℃,300 ℃,400 ℃,respectively to study the temperature field distribution and energy saving.The experimental results of temperature field distribution shows that under the same target temperature,the experimental condition of which that the speed of wind is 3m/s increases the temperature gradient of flange joint,but the overall temperature of flange joint is close to the target temperature after insulated.The results of energy saving experiment shows that the most electricity consumption was the uninsulated flange joint under the condition of which the speed of wind is 3m/s,And the energy saving efficiency of the flange joint after insulated can reach at 32.7%.Considering the air layer in the flange joint has influenced for the temperature field distribution,the finite element model of bolted flange connection system was established secondly based on the experimental conditions,the steady-state thermal analysis and heat loss analysis under different experimental conditions were carried out.The analysis result shows that the temperature distribution of the bolt flange connection system was symmetry of the gasket,and the temperature was gradually reduced from the inside to the outside.The average error and maximum error of measured temperature and simulated temperature were 7.55% and 14.76%respectively.The reliability of simulation was verified in the range of error which lays the foundation for thermal structure coupling analysis afterwards.Then the thermal structure coupling analysis of flange joint under different temperature field conditions was carried out.The result shows that the stress distribution of flange joints under various conditions has obvious symmetry;The stressof the gasket decreases gradually along the radial direction,but remains unchanged along the circumferential direction;The stress of the joint is increased in which condition the speed of wind is 3m/s,and the stress of the joint was reduced when the flange joint was insulated;Combined with JB 4732,the strength of each dangerous section of the joint under different working conditions was evaluated;The sealing performance of the flange joint in the 9 simulated conditions was evaluated with the initial seal ratio pressure and the minimum gasket pressure.Finally,a leakage monitoring and early warning system for in-service bolted flanges was designed,which can realize real-time monitoring and early warning for flange joints in key parts of the whole plant.The system was helpful to avoid the environmental pollution caused by leakage,the injury of personnel and the economic loss caused by parking.