Investigation On Experimental Platform For Determination Of Dust Explosion Characteristics

The dust explosion hazard is a continuous threat to environment and process industries that manufacture use and handle powders and dusts of combustible materials. Dust explosion characteristic parameters are important base of risk assessment, prevention and protection of dust explosions. Research and development of an experimental platform for accurate determination of the dust explosion characteristics is significant for process safety.The main dust explosion characteristic parameters include:maximum explosion pressure (pmax), explosion index (Kst), minimum explosible concentration (MEC), limiting oxygen concentration (LOC), minimum ignition energy (MIE), and minimum ignition temperature of dust layer and cloud (MITL and MITC). The equipments for determination of dust explosion characteristics were developed, and the relevant experiments were carried out. The main work is as follows:(1) An experiment platform based on Ethernet and OPC technique was built. PLC ladder program, configuration process of human-machine interface, and data acquisition and database management applications used at the host computer were designed.(2) Using the high energy electrostatic spark generator as the ignition source, differences and correlation of chemical ignition and electrostatic ignition in the determination of Kst and MEC were studied. The reason of deviation of result obtained using electrostatic ignition compared to those obtained using chemical ignition in the test of dust explosion parameters was investigated. The feasibility that electrostatic ignition can be used as an alternative ignition to the chemical ignition was demonstrated. The correction method for convert test results obtained with electrostatic ignition to results obtained with chemical ignition was preliminary explored.(3) The spark energies of the high energy generator system and minimum ignition energy test system were determined using integral method. The energy loss in the process of discharge was analyzed. The diversity and relevance of the integral energy and nominal energy were discussed.Through the development of the platform and research of the related experiment, the following conclusions were drawn:(1) The developed platform has been applied in actual production and achieved very good results with the advantages of safety, independence, integrity, scalability, real-time and high precision. Experiments proven that, the devices in the platform are in conformity with the relevant national and international standards.(2) For the Kst test in the20L confined test vessel, results using electrostatic ignition with the same nominal energy (stored energy in the capacitor) are lower than the chemical ignition, but basically meet the linear relationship. For the MEC test, the results with electrostatic ignition are higher than the chemical ignition, but they could be the same by increasing the nominal energy of electrostatic ignition.(3) The energy of the spark measured by the integral method is lower than the nominal energy and they have linear relationship. The discharge efficiency (ratio of measured energy to nominal energy) decreases along with increase of the nominal energy.