| Manure of large farms has been one kind of the main environmental pollution sources. With the aggravated environmental pollution and non-renewable resources like coal, oil becoming increasingly tense, as one methods of turning waste into gold and protecting environment, methane fermentation is significant, and captures more and more extensive attention at home abroad. In fermentation process, how to maintain a higher gas production rate all the time is the standard to test if a biogas project is successful, and then monitoring the fermentation process parameters becomes the key technology. Now industrialization of biogas production in Heilongjiang province is ripe, but the automatic control level of fermentation and production efficiency is relatively low.Methane fermentation is cultivating anaerobic digestion bacteria. For the process is complicated and Heilongjiang is in alpine region, only relying on natural fermentation is difficult to realize industrialization. Monitoring the biological environment of fermentation process is necessary. Then it can provide for fermentation bacteria with a good growth and propagation environment, so as to maintain a higher gas production rate. Of all the factors, temperature, digestion load, pH, pressure are the key factors in the breeding environment of methane fermentation microbial.Through analysis and research of principle of the fermentation technology and fermentation process, temperature, pressure, liquid level and pH are determined for study. The system based on PC, using virtual instrumentation which is the technology combination of sensor, instrumentation and computer, as the development platform, making full use of its intelligent functions like operation, storage, playback, call, display and document management to research the methane fermentation monitoring system. Use M-series multiple data acquisition card (DAQ) PCI-6221 of NI as the core, with the corresponding sensors and signal conditioning circuits to complete the system hardware design; In the development environment of virtual instrumentation software-LabVIEW-through programming, the key process parameters can be real-time monitored and displayed, historical data is stored, which is to be day-to-day managed and analyzed in the future, at the same time. The temperature monitoring subsystem uses the fuzzy control algorithm to realize monitoring; the infinite impulse response digital filter-elliptic filter-is for the interfering factors in DAQ acquisition signal.The system uses advanced virtual instrumentation nowadays to research methane fermentation monitoring system. The experiments show that the system meets the monitoring requirements, and through computer large-screen, managers can real-time master all kinds of conditions in scene, analyze production data, combine control and management, so as to improve control precision and has a excellent scalability. It provides a highly efficient and reliable mean for methane industrialization production. |
