| Petroleum and its products is a mixture of many different hydrocarbons, which is highly volatile at the room temperature. The oil has a widespread problem of evaporation loss in the whole process of transportation from the depot to the gas station and then to users. Oil evaporation loss will bring a lot of harm, such as waste of resources, environmental pollution, health hazards and so on. In order to reduce hydrocarbon emissions, a versatile tank truck vapor recovery detection system was developed according to the "Emission standard of air pollutant for gasoline transport", which makes the tank truck vapor collection system digitalize, visualize and automated detection.The versatile tank truck vapor recovery detection system adopts a manual control valve way to reach the purpose of the vapor recovery system pressurized to 4.5kPa in its positive pressure tightness detection process. However, the pressure within the vapor recovery system is very unstable in the load process, which range of fluctuations is associated with the flow characteristics of pneumatic circuit, air pressure, tank volume, temperature and other factors. The load process of manually controlled recovery system is difficult to make the air pressure keep at a stable value of 4.5kPa after loaded, which seriously affects the efficiency and accuracy of performance detection of tank truck vapor recovery system.To solve above problems, in this paper, automatic load technology in the process of the tank truck vapor recovery system was researched on the basis of versatile tank truck vapor recovery detection system. Besides, some improvements has made on versatile tank truck vapor recovery detection system according to automatic load technology, thus, an automatic precision detection system for vapor recovery system of tank truck was developed, which achieved a fully automated detection, and solved the problem of inaccurate in the manual load. The main research methods and conclusions were listed as follows:(1) Automatic precision detection system for vapor collection system of tank truck consists of microcontroller module, power supply module, display module, clock module, data storage module, data acquisition module, the solenoid valve control module and automatically load modules, which can gather pressure and temperature data, display and storage of detection information in real time,and automatic control system loading processes.(2) In this paper, a technical solution of automatic load of automatic precision detection system for vapor recovery system of tank truck using Newton iterative method based on the inflated and the deflated characteristics of a constant volume was proposed.(3) In this paper, software design of detection system was completed, which has functions of automatic load, positive pressure detection of vapor collection system, positive pressure detection of pipeline and pneumatic valve, negative pressure detection of vapor collection system based on the detection method of automatic precision detection system for vapor collection system of tanker truck(4) In this paper, three automatic load experiments of tank truck were conducted using automatic precision detection system for vapor collection system. In the experiment, the target pressure of the automatic loading is 4.5kPa, after automatic load, the pressure stabilized at 4.510498kPa,4.462891kPa and 4.594727kPa, verified automatic precision detection system for vapor recovery system of tank truck achieved the function of automatic load.(5) In this paper, the air pressure inside the tank is very unstable when loading tanker vapor recovery system in the automatic load experiments. Fluctuations in air pressure ranged up to 0-0.387kPa. The pressure fluctuation also reached 0-0.387kPa when adopting the manual loading under the same test conditions. While the range of variation was as small as-0.04-0.09kPa compared to the target pressure 4.5kPa after loading when using the automatic load, which fluctuation range of atmospheric pressure was far lower than the manually loaded 0-0.387kPa, it proved that automatic precision detection system for vapor recovery system of tank truck can effectively solve the problem of inaccurate of the manual load.(6) In this paper, positive pressure detection of vapor collection system, positive pressure detection of pipeline and pneumatic valve, negative pressure detection of vapor collection system were earned out by automatic loading technique. Experimental results show that the full automatic precision detection system for vapor collection system of tank truck scientific and accurate evaluation of the performance of tank truck. |
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