Study On Erosion Law Of Panyu 35-2 Submarine Gas Pipeline

According to the Panyu35-2submarine gas pipeline system which the sand grain content of the transmission medium is in the range of5×10-5kg/s～1×10-3kg/s, in the continuous mining and operation process, the sand in flow medium will continue to impact the pipeline wall and cause a certain degree of erosion, but it is unknown of the Panyu35-2submarine gas pipeline that the incidental position of the erosion, the erosion state of the current conditions, the influence degree of the erosive action to the normal running pipe and what measures should be taken to prevent such problems. Therefore, in view of the above problems, the erosion model was established based on the theory of fluid dynamics and erosion, and using the method of combination of theory and simulation, erosion simulation prediction of the jumper pipe, T tube and throttle valve in the piping system was done by using ANSYS Fluent software, and the comparison simulation and analysis of the different influence factors was launched, which provides a basis for the locating the erosion placement accurately and making prevention measures.The concrete research contents and main conclusions are as follows:(1) The micro cutting theory, deformation wear theory, forging extrusion theory and secondary erosion theory was established to provide the reference for the concrete shape of the sand caused by erosion of Panyu35-2submarine pipeline.(2) The erosion model of gas transmission pipeline was established which provides a theoretical basis for the subsequent erosion simulation. The continuous phase using RNGk-ε model, and the particles phase using discrete phase model, to realize bidirectional couple of the discrete phase and the continuous phase, the continuous phase control equation and discrete phase motion equation was alternately computed. The erosion rate model used the erosion rate formula defined in Fluent, and the discrete phase boundary conditions were set respectively, and the near wall region was handled by the wall surface function method, and the control equation was discretized by the finite volume method, and the coupling relationship between pressure and speed was solved based on SIMPLE algorithm.(3) The independent of mesh was analyzed, and multiple sets of simulation data was contrasted and analyzed according the criterion of y+. The way of the grid division and boundary layer setting was determined, which avoided the simulation results error caused by grid factors, and verified the validity of the erosion simulation, and the feasibility and accuracy of simulation was verified by comparing the simulation results and the examples.(4) The erosion position was obtained through analyzing the jumper pipe, T pipe and throttle valve in the Panyu35-2submarine gas pipeline system:゜end outer arch of the jumper pipe;②upstream wall and the delivery end bottom of T tube intersection;③the valve core upstream wall, the junction of the valve core and orifice, and the pipe end inside wall of the throttle valve. The maximum erosion rate of the simulation was obtained, and that is0.54mm/a,0.11mm/a,0.34mm/a, which indicated that the pipeline system could be normal operation under the transporting media with sand and in the current conditions, but there would be some risk in the late design life, and it is necessary to take some preventive measures.(5) The influencing factors were analyzed by using the single variable method for jumper pipe and T tube, and the groups of erosion simulation model was established, by setting different variables, the alter regular was obtained as follows:①the erosion rate increasing with the increasing of the flow rate;②the erosion rate increasing with the mass flow rate increasing;③the erosion rate decreasing with the shape factor increasing, but the decreasing magnitude was bigger when the shape coefficient is between0.3and0.6, and then decreasing gradually;④the erosion rate decreasing with the diameter increasing first, then increasing again, and reaching a certain value.(6) The conclusion that the erosion rate was affected most by the flow rate was obtained by using the grey correlation analysis method, and the valve of the sand diameter, sand mass flux and the shape coefficient were closely, but was smaller than the former. Therefore, the key to reduce erosion is to control the flow rate. On the basis of the above analysis, some measures to prevent or mitigate erosion were put forward. In the actual production, it can take measures to thicken the erosion parts, control sand flow or mass flow and conduct regular safety inspections and so on.It can accurately find and locate the potentially dangerous position of Panyu35-2submarine gas pipeline system from the erosion rate images obtained by the simulation, and taking some preventive measures can effectively guarantee the pipeline safe operation and avoid the loss caused by the damaged pipeline.