Location of the inlets and outlets of Chinese dome digesters to mitigate biogas emission

A model based on three equations was developed and validated for the design of the inlet and outlet of the Chinese dome digester (CDD) to prevent biogas emission or leakage. The model was implemented in MATLAB software and validated with results from a pilot study. Biogas and temperature data from the pilot experiment were used to validate the model and the results fitted well with the experimental data at low gas volume (<20 mols) but with some slight deviation at high gas volume. The model predicted the reactor pressure (P_G) and the slurry displacement in the expansion chamber, inlet pipe head (h) and head inside the digester (h_G). The relationship between the gas and h was not linear at high gas volume (>20 mols). The model can be used to predict the optimal size of the CDD for daily biogas storage based on different reactor and expansion chamber sizes, in order to mitigate the emission of surplus biogas from the inlet and outlet pipes.