Flame Characteristics of Biogas from Coffee Waste Materials

Abstract

Biogas flame characteristic from coffee waste has been investigated. The biogas flame characteristics include the content of carbon dioxide in biogas, flame color, ionic behavior in flame, and caloric value. Biogas is made from coffee shell waste material mixed with cow dung on ratio 1:1. The reactor used is a continuous system with a floating system as biogas storage. The resulting biogas was purified by using 1 M and 4 M KOH solutions, and measured carbon dioxide content using a gas analyzer. Biogas turned on a bunsen burner and a flame recorded with a camera, on resolution 1280 × 720. The resulting image is analyzed for the color of the flame on several compositions mixed with air. To measure the behavior of ions, biogas and air mixes are ignited inside the combustion chamber Hele Shaw Cell (HSC) that made of acrylic with dimensions of 30 cm x 20 cm and 1 cm. The ion sensor is made of 1 cm wide aluminum foil mounted to 1 cm in length along the HSC. Flame will produce ions that indicated by the emergence of voltage of ion sensor. After the biogas composition is known, the calorific value can be calculated. The results showed that CO2 content before purification was 37.22% and purification caused CO2 content decrease to 23.01% in KOH 1M and 18.66% in KOH 4M. Decrease CO2 composition causes an increased combustion reaction as indicated by increasingly blue flame color and larger ions. This result is reinforced by the calculation of calorific value, in which the decrease of CO2 content in biogas causes the caloric value increase.