Gas Pipeline Detector In Speed Regulation System Of Research

Inner inspection is the most reliable way to conduct a detection in the defects of the gas pipeline. Usually, the long-distance pipeline is using a non-cable type detector. Because of the flow rate changed no law、ups and downs of the pipeline、deformation and some another factors led to the speed very unstability of the inner detector. Currently, many of the commonly used inspector need the scanning speed between0.5m/s to4m/s.we need to control the speed of the inner inspection tools to avoid the missing defect and improve the effectiveness and efficiency of the detection. In order to eliminate the pressure fluctuations caused by changes of gas flow rate, this paper will using a bypass device to achieve this goal.The inner detector has two parts, the first one is the travel drive system, the second is the detection system. There are two rubber cup in the drive section used for seal and cut off the fluid in the pipeline. The detector driven by the pressure of the transmission gas, and the probe inspect the defects of pipeline, also there are unit for date processing and storage.Differential pressure as a feedforward control volume in the detector speed control, used to eliminate the impact of gas pressure fluctuations within the gas pipeline on the speed of the detector. This paper is using a bypass device, there are four discharge hole opened in the steel plate, we can control the size of the discharge hole and change the gas flow to eliminate differential pressure fluctuations before and after the tools,the pressure changes will be offset prior to the impact of detector speed. Using a pipe of the diameter is660mm and drive section of detector to create a simulation model, and created mesh according to the finite volume method(FVM), through the analysis of the flow field in the pipe, we can learned that the turbulence model SST is more reasonable for the gas flow in the pipe. In order to get the relationship between the size of the discharge hole and the differential pressure before and after the tools to employ the software of ANSYS CFX to conduct a numerical simulation, incidentally, obtain the equation between flow speed and the hole size.Numerical simulation and the result of simulation provides a reference for the design and the speed control of the inner detector. In addition, besides the research of this paper about the speed control,there are a lot of problem needs to solve, such as, to seek more reasonable turbulance model for the gas flow in the pipe, optimize the mechanical structure of the discharge hole, the control algorithm need to probe thoroughly, advance the leak tightness of the rubber packer cup, improve the material of the rubber cup and so on, all of them need to solve.With the development of computer the numerical simulation of fluid flow as a new science emerging. It is a new way to probe the speed control of the inner detector. The most advantage of this way is low cost, and it can solve some problem when physical condition is shortage.