Operating principle and structural optimization of impulse type anti-blocking distribution device for biogas manure

Abstract: As a result of rapid development of economy recently in China, energy consumption has increased. The total energy demand has increased with the average 8% annual rate from 2.1 billion tons of standard coal in 2004 to 4.3 billion tons of standard coal in 2014 during the past 10 years. Searching for alternative energy to easy the energy supply pressure is imminent in the face of the enormous energy demand. To lower the energy supply pressure, biogas engineering which is based on biogas fermentation technology has been the one of the sources of alternative energy. Biogas engineering alleviated the energy demand partly. However, the vigorous development of biogas brings a problem of a large number of biogas slurry and biogas residues which cannot be timely treated, especially for large and medium sized biogas facilities. Biogas slurry and biogas residues that have the characteristics of large amount and continuation will pollute the environment if without immediate treatment. Therefore, one of the important processing methods is that biogas slurry and biogas residues are used as a source of fertilizers for agriculture production. A machine was developed to treat biogas manure effectively at Northeast Agricultural University. Considering the biogas slurry and biogas residues might block easily in the process of multipath distribution and transportation, and the conveying passage might be blocked completely by the accumulation of sediment with time increasing, a pulse type biogas manure anti-blocking distribution device was used to solve the above problem innovatively. An invention patent of the fluidal mixed materials handling anti-blocking distribution device has been applied as a result of such research and development. The dredge pipe was built in the device to prevent block but the working mechanism and structure was expected to be further studied. To define working mechanism of impulse type biogas manure anti-blocking distribution device and provide theoretical basis for the engineering application and structure optimization, we took five passages of distribution device as research object. By using the water hammer pressure and water hammer vibration mechanism, the device on different number of the blocks was simulated by CFX computational fluid dynamics software. As such, the pressure waves at discharge hole on different number of blocks were obtained. In the simulation, five discharge holes were closed at the same time while other five blocks distributed equality on the circle at a speed of 37.8 rad/s, which could be determined through analyzing the pressure waves. For the structure optimization, the flow fields of the device with or without distribution conical structure were analyzed, the optimal taper of the cone was determined. The effectiveness of distribution conical structure was verified. Meanwhile the protective structure avoiding large particles was designed. The impulse type biogas manure anti-blocking distribution device and the distribution conical structure were integrated. The visualization test device was designed and processed according to the optimization scheme. We observed the material flow state in working mode of impulse type biogas manure anti-blocking distribution device, and measured the pressure waves in the discharge holes. The results showed that the test results were consistent with the simulation results, and the relative errors of the peak-valley values of the pressure waves were within 10%.