Experimental Study On Strength Of Austenitic Steel Small Header In 630? Ultra-Supercritical Unit

In response to the national call for energy conservation,emission reduction and sustainable development,to achieve the goal of transformation and upgrading of the thermal power generation industry.the development of higher-parameter and higher-efficiency units has become an important development goal for thermal power units.A boiler plant encountered a material bottleneck in header manufacturing when developing and constructing a new 630? ultra-supercritical coal-fired generating unit.At present,there are no mature materials that can be used directly in the manufacture of 630? ultra-supercritical unit headers.For this reason,a boiler plant has proposed a P92 header+austenitic steel small header solution to solve the problem of header materials of 630? ultra-supercritical units.Before the new austenitic steel small header is applied to the actual power plant,the strength check test and thermal fatigue performance test must be completed in the laboratory.However,because it has no relevant test and application data,it is necessary to perform numerical simulation and experimental tests on its stress/strain and thermal fatigue performance in service.This article takes the austenitic stainless steel small header simulation produced by Harbin Boiler Plant as a research object,and builds a high temperature and high pressure test platform to carry out increase load,decrease load,stable load conditions and long-term high temperature conditions stress/strain test for the header simulation.And ANSYS finite element analysis software was used in combination with the analysis of calculation requirements to establish an optimized finite element calculation model that was easier to calculate after the optimization.The numerical simulation calculation and comparison of stress and strain calculation results with actual test results were performed.The comparison of the experimental and numerical simulation calculation results shows that the actual axial and circumferential stresses and strain changes of the outer surface of the header simulation component under the conditions of rising load,decreasing load and stable load are close to the results of the simulation calculation,and the change trend is more consistent with the stress.The strength is lower than the yield strength.After prolonged thermal fatigue test,no cracks were found on the outer surface of the header and each weld,and the outer surface was oxidized severely.These results laid the foundation for the subsequent application of small headers of austenitic steel.