| Dangerous goods such as liquefied petroleum gas are frequently transported by tank trucks,which have adverse effects on personal safety,ecological environment and economic development.Therefore,regular inspection of tanks is essential.For the detection of the tank,it is necessary to exhaust the residual gas in the tank and manually enter the tank for testing.For the safety valve installed on the tank,it needs to be removed and placed on the safety valve calibration table for verification.In order to solve the problem that the residual gas in the tank is difficult to exhaust and the safety of the safety valve is low,a tank check valve and a gas exhaust system are designed.The specific research contents are as follows:(1)On the basis of consulting a large number of relevant domestic and foreign literatures,the overall planning of the system,including on-line verification of safety valves and the exhaustion of tank gas,mainly completed the design of the hardware circuit,the design of the mechanical structure,the design of the software program.(2)The design of the mechanical device mainly includes the design of the calibration device,the design of the displacement calibration table,the design of the exhaust control box,and the design of the trolley.(3)The Hardware circuit design mainly includes power supply circuit design,single chip circuit design,signal amplification circuit design,filter circuit design,solenoid valve drive circuit,PCB circuit board drawing and so on.(4)The program design is mainly the lower computer program and the upper computer program design.The lower computer program mainly realizes the control of the stepping motor,the acquisition of the output signals of the Hall sensor and the tension sensor,the processing of the data,the display on the liquid crystal display,the control of the solenoid valve,etc.;The upper computer program mainly realizes drawing the tension and displacement curves on the screen of the data sent by the lower computer,displaying the measured data,and storing the data for convenient viewing.(5)The calibration test of the displacement measurement of the calibration device is completed on the displacement calibration table.The output voltage and displacement data of the Hall sensor are obtained through a large number ofexperiments,and then the piecewise linear fitting is performed to obtain the correspondence between voltage and displacement.Within the detection range of23 mm,the error is within 0.2mm.In addition,the safety valve calibration test was carried out on the calibration device.The comparison result was compared with the verification result of the safety valve calibration table.The relative error was within3%,and the error was within the acceptance range.This topic combines the calibration of the safety valve with the exhaust of the tank,which has certain innovation and practicality.Compared with the hydraulic valve system,the system has the advantages of simple operation,high speed and convenient disassembly.It has the advantages of high efficiency and environmental protection in tank exhaust.However,the accuracy of the displacement and tension measurement of the calibration device can be further improved,the device sealing needs to be strengthened,and the exhaust system needs to be further improved,and further research is needed in the future. |
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