Monitoring the Air-fuel Ratio (AFR) of a Biomass Gasification Process with an Arduino Uno 3 and a Narrow Band Lambda Oxygen Sensor

The Air-Fuel Ratio is one of the keys parameters for driving the gasification process. Monitoring of oxygen percentage in flue gases is one of various ways of controlling efficiency and emissions of industrial combustion. Biomass gasification is a thermochemical degradation of the biomass that is accomplished with the Air-Fuel Ratio less than the stochiometric one that is used in the combustion.

Unfortunately, flue gases analyzers in combustion processes are expensive and not accessible to small scale industries. This is particularly true in developing countries. The Lambda sensor used in the automotive industry is an oxygen sensor which controls the electronic injection of the modern internal combustion vehicles.

The aim of this study is to present one simple method of measuring the oxygen concentration and calculate the Air-Fuel Ratio in synthesis gas produced by a downdraft biomass gasifier by the use of an Arduino Uno 3 microcontroller and an automotive Lambda sensor. This method use the voltage signals developed by a heated 4 wires Lambda sensor and the Nernst Equation to calculate oxygen concentration in the producer gas and derive the Air-Fuel Ratio.

Results presented in this article show that this method is a simple and cost-effective way to monitor Air-Fuel Ratio in a biomass gasifier.