The Research Of High Pressure Feed Water Heater Of Power Plant Security Evaluation

As a gas-liquid tubular exchanger,the high pressure feed water heater widely used in firepower,nuclear power generation system.The steam from turbine is used to heat the water in boiler.It can reduce the steam to condensers and the cold source,improve the cycle heat efficiency,on the other hand,due to the high temperature feed-water,the boiler heat load is reduced and heat exchange area in furnace is reduced,that can reduce the steel mass,ensure the output of power plant,improved the cycle heat efficiency.The high pressure feed water heater is running under the high pressure and temperature,so it is the most dangerous equipment.It will bring a great loss once failure.At the same time high pressure heater has run continuously for a long period of time,therefore it can not be implemented a comprehensive inspection,etc.So the research of inspection methods of high pressure heater,for the safety assessment of pressure vessels containing defects,reduce or avoid the accident,ensure the safe operation of the power plant and the lives and property of human,promoting economic development,is of great significance.The heater works under high temperature and high pressure,so the plate withstand impact from thermal stress and load together.The domed chamber water head and tube plate junction must be strictly controlled to ensure safety under such conditions.In this paper,the investigation used with numerical simulation and experimentation.Through a variety of nondestructive testing methods for the key parts of the high pressure feed,obtain the test results,and analyzed the superiority and inferiority of various detection methods.This study uses the phased array testing and time of flight diffraction advance nondestructive testing method.At same time through advanced inspection means,such as optical spectrum in the microscopic structure of the material,the forming mechanism of defects research provides a basis in this paper.The main contents of this thesis are as follows:(1)The research object as welding defects with high pressure feed water heater tube plate and the outer surface of the cylinder connecting arc transition section,analyzes the reasons of the defects.(2)The application of phased array inspection technology and TOFD detection technology in the detection of defective.(3)The analysis of parent metal and weld defect parts of conventional mechanical properties and fracture toughness parameters.(4)By the finite element method,the model containing defects is established.Through the calculation of model to get the stress distribution and temperature distribution.On this basis,the strength was check for the basis of theoretical analysis for the safe operation of the heater.(5)Used in the safety assessment of pressure vessels containing defects related standard safety evaluation for defect parts,reduce the number of unnecessary repair,improve the economic benefit,on the premise of ensuring security to reduce the enterprise production loss.