Research On Water Hammer Analysis And Optimal Protection Of General FPSO Key Pipe Network System

With the continuous improvement of FPSO system operation capability and operation field,FPSO has become the mainstream means of offshore oil and gas development for different deep water and different environment.In order to adapt to a wide range of environmental conditions and the demand for oil and gas exploitation in deep water field,the multi-functional and long-life deep water general FPSO emerges as the times require.The complexity and compactness of its pipe network system are closely related Compared with the traditional FPSO,the water hammer / air hammer effect may be formed in the key system of FPSO.Compared with the water hammer,the probability of air hammer is very small.Therefore,water hammer,as a common fluid shock and vibration phenomenon with relatively large potential harm and damage degree in the FPSO pipe network system,is necessary to reduce the damage probability of water hammer and improve its safety and economy It is more and more important to master the key technology of water hammer numerical simulation analysis of general FPSO pipe network system,and finally build an effective water hammer protection technology system.In this thesis,the cargo oil pipe network system and ballast water pipe network system of deepwater general FPSO are taken as the research objects to optimize and protect the water hammer,and the compressed air system is taken as the secondary research object to study the air hammer effect.The main research contents are as follows(1)Establish the corresponding compressed air system,through aft impulse software,establish its relevant model,and mainly analyze the valve closing air hammer of compressed air system,study whether the maximum pressure position of air hammer phenomenon meets the design requirements.(2)The dynamic fluid analysis software aft was used According to the PED drawings and relevant data,the parameters of various components and equipment in the model,such as pipe diameter,flow rate,pipeline material and other necessary parameters,are set.Combined with the design,the water hammer simulation calculation and analysis are carried out,and the maximum pressure position of the water hammer phenomenon is obtained,which is an important basis for safety analysis and pipeline design.(3)In the process of water hammer formation,valve closing and pump stopping are most likely to cause water hammer,so this thesis studies the two kinds of water hammer In impulse software,Newton Raphson method is used to solve the basic formula of steady-state flow to get the maximum static pressure;characteristic method is used to transform momentum equation and mass conservation equation,combined with equipment boundary conditions to solve the transient to get the maximum water hammer pressure,which has guiding significance for the optimization of water hammer and the selection of protective measures.(4)According to the mechanism of water hammer,the working conditions of water hammer effect are optimized and protected.The system safety is improved by extending the straight-line valve closing time,using slow closing butterfly valve for two-stage valve closing,adding pressure regulating tower in the pipeline to eliminate the positive pressure water hammer in the pipeline and closing the negative pressure water hammer in the pipeline.