|Portable biogas analysers are ideal for manual sampling or interval monitoring for varying requirements for one or more sampling points as regularly as needed. Geotech's BIOGAS 5000 is a portable biogas analyser with a variety of gas range options, including CH4, CO2, O2, H2S, NH3 and H2. Portable biogas monitoring can assist with process control and analysis.|
|Fixed biogas analysers can be used for continuous or automated sampling at user-defined monitoring intervals for single or multiple sampling points. The GA3000 PLUS from Geotech can be used for up to 3 sample points for CH4, CO2, O2, CO, H2S and H2. Fixed gas analysis can be crucial for CHP protection and revenue generation|
The quality of the biogas and its value as a fuel is the key reason for investing in an AD plant. The case for monitoring biogas can be made commercially, with some reasons applying to all plants and the strongest case applying to a plant with a CHP engine, particularly where feedstock is varied:
The key gas is methane (CH4). As well as providing an indication of AD output, it should also be measured in order to protect a CHP engine. It is obviously highly explosive and engines are sensitive to sudden changes in methane levels, as well as requiring a minimum CH4 level to restart.
Hydrogen sulphide (H2S) is often produced during AD, particularly with high protein feedstocks such as maize. As H2S turns into sulphuric acid in the engine, high levels can cause damage. AD plants with high H2S often use H2S scrubbers to remove the H2S before the biogas reaches the engine. In this case it is a good idea to monitor H2S before and after scrubbing to keep an eye on the effectiveness of the scrubbing process.
Carbon dioxide (CO2) and oxygen (O2) are also useful indicators to monitor. The CH4 / CO2 balance can help confirm effective AD. O2 levels show that the process is anaerobic and there are no inward.