Liquid Chemicals Auto-ignition Temperature Testing Device Based On The PIC Micro Control Unit

The dangerous chemicals refer to the chemicals that have the feature ofinflammable, explosive, poisonous, corrosive, radioactive and other dangerouscharacteristics, which easily cause property, human lives damage and environmentalpollution. Its production are monitored by the national testing institutions. Theauto-ignition temperature is one of the key parameters to show its danger level. Theoutput of dangerous chemicals grow rapidly with the development of China’schemical industry. At the same time, accidents caused by chemicals are verycommon which lead to serious loss to the enterprise and people’s lives and property.During international trade, some key physical and chemical parameters are requiredto be provided such as spontaneous ignition point. So chemicals self-ignition pointmeasurement is very urgent, chemical self-ignition point test equipment’s researchhas become necessary.Due to the chemical industrial developed early in Europe and America, thestandard for liquid chemicals’ self-ignition point measurement test method is mainlyfrom Europe and United States, such as ASTM E659，DIN51794，IEC60079-4andEC test A15. In China, related standards are publicated, such as GB/T21791、SH/T0642—1997and GB/T21860—2008. Therefore, some liquid chemicals self-ignitionpoint testing equipments have appeared in the market, for example AITTA whichproduced by IDEA SCIENCE, and Liquid chemicals spontaneous combustiontemperature meter supplied by KOEHLER. At present, there is no similar equipmentin China. According to the standard of GB/T21860—2008, this thesis realized thedevice from theoretical research to the engineering realization. The main contentsand innovative points summarize as following:(1) Based on GB/T21860—2008, study and manufactured the liquid chemicalsself-ignition point test device which hasn’t appeared. The device includes fourcomponents, the layout of crucible furnace heating apparatus, the control unit hardware and software on data acquisition circuit are designed, the real-time dataacquisition and parameter extraction based on LabVIEW are developed, thedebugging of the device and the test of liquid hazardous chemicals auto-ignitionpoint are finished.(2) According the Natural standard, the Fuzzy PID rules are built. In terms ofthe furnace’s temperature rising faster in low range than that in high when at itsworking temperature0°C~1000°C and the requirement of national standard toconfirm the auto-ignition point must regulate the temperature at30°C and3°C.Simulated the system’s overshoot and stability using Fuzzy PID controller.(3) Designed and realized this system’s software and hardware based on PICmicro control unit, four K type thermocouples’ temperature data acquisition werecarried out, displayed and transmitted those data to PC software interface. The PCsoftware was used to extract parameters of liquid chemicals based on GB/T21860—2008. At last, test the auto-ignition point of93#gasoline, acetic acid,petroleum ether, nitrobenzene, methanol, Phenol and aniline by this device anddetailedly gave out the results.Finally, the thesis discussed the device’s application prospect and the parts canbe improved.