Abstract: Biogas production rate in the bench-scale fermentation reactor is commonly low, and it is difficult to obtain the precise data of biogas production. This study designed a biogas flow meter that is suitable for bench-scale fermentation reactor. During the operation of the flow meter, the continuously produced biogas is discretized and then measured, and the biogas volume in each measurement batch is determined by the pressure change in the biogas collection chamber with the constant volume. The control system of the flow meter takes the single chip microcomputer as the core part. Based on the predetermined pressure parameters, the automatic switch of the situation between “receiving biogas” and “emitting biogas” in the biogas collection chamber could be achieved. The data of the key parameters that is automatically collected and displayed in the control system is used for the calculation of biogas flow.

Key words: biogas flow metering, low production of biogas, bench-scale, automatic controlling