Design Of Leak Detection Device For Hydrogenation Air Cooler

Taking Sinopec Yangzi petrochemical aromatics plant 1 # hydrocracking unit of air cooler EC102 as the prototype,in the thesis the device to detect the leakage of hydrogenated cracking air cooler is designed.Currently the leakage detecting device used on EC102 is alarm device of combustible gas sensor,which has larger residual risk and poor real-time performance.And the way of inspection which needs the worker to climb over the cooler to check the gas concentration is not very convenient.Aiming at the defects of combustible gas leakage detection device,the leakage detection device designed in this thesis combines the gas leak detection technology and the ultrasonic leakage detection technology together.To achieve the comprehensive coverage of the hydrogenated cracking air cooler leakage detection arrangement model of the ultrasonic sensor nodes is studied.The sink note using wireless networks receives the data collected by each sensor node,and the gateway merges the gas concentration data and the ultrasonic sound pressure level data to calculate the possibility of leakage and display the relevant data on the LCD.In addition,the leakage data can also be transmitted to the control system to achieve the real-time transmission of field leakage situation via the factory network.The main contents of this thesis are as follows:1.The gas sensor node and the ultrasonic sensor node to detect combustible gas signal and the ultrasonic signal are designed when air cooler leaks.The gas sensor is catalytic combustion type TGS6812-D00 combustible gas sensors.The amplification circuit and the ZigBee radio frequency circuit are designed and the sampling conversion program to obtain the gas concentration data is programmed.The ultrasonic sensor TC40-A18 is selected by analyzing the principle of ultrasonic leakage detection.The location mode of ultrasonic sensor nodes is presented to realize the universal coverage of air cooler.The ultrasonic signal analog amplifying,filtering,programmable amplifier circuit,signal processing and ZigBee radio frequency circuit are also designed.The Fast Flourier Transform(FFT)program is designed to extract the characteristic data of the signal.The function of gas and the ultrasonic sensor nodes are tested and the gas sensor node can detect the concentration of combustible gas,and the ultrasonic sensor node can extract the amplitude data of characteristic signal.2.The ZigBee communication technology is used to realize network construction for data transmission between convergent node and sink node.The Linux operating system is transplanted and the LCD driver is written on the gateway node.The membership functions of the gas concentration,the gas concentration change rate and the ultrasonic sound pressure level are given by analyzing the fuzzy theory to the multi-sensor input fusion method.And then the fusion algorithm is implemented on the Linux system,including data reception,data preprocessing and fusion judgments.Base on the multi-sensor wireless network,the multi-sensor fusion algorithm is tested,which shows that the wireless network data transmission function and the multi-sensor fusion application program have been realized.3.The conclusion is drawn by analyzing the test data from leak detection,showing that the accuracy of leakage detection using the multi-sensor fusion method is higher than that of using a single sensor solely,reducing the wrong judgement possibility of leakage accident.