Pilot tests: a blessing for high-performance installations

Having installations function optimally is usually best achieved if they are fully in line with the company needs. Laboratory tests often give a good indication, but pilot tests on site allow exact data to be used to select the right activated carbon type for a project, while allowing continuous, high quality purification.

DESOTEC is currently using this approach at an important waste processing company. This company distils biogas from household waste and turns it into high quality biomethane, that is practically as pure as natural gas.  The in-series setup of the two activated carbon filters treats a flow of 300 m³/h.  It removes H2S up to the required level for the production of biomethane, while also eliminating organic components (VOCs) from the biogas.

In-series setup

For the purification of biogas into biomethane, the company uses a purification line in which activated carbon filters also play an important role. The activated carbon removes hydrogen sulphide (H2S) from the biogas to increase purity and protect the further purification stages from this harmful compound. To find the right solution, DESOTEC installed two AIRCON HC XL filters in series at the customer’s site. The in-series setup increases efficiency: this allows continuous purification with the capacity of each filter fully utilised. When the first filter is saturated, the second filter takes over and the first filter can be replaced.

The biogas is drained at a certain point and then sent over a parallel pilot installation,  where it is treated by two types of activated carbon. The treated gas is subsequently returned to the production plant without any loss.

Test types

Two different tests were carried out with the pilot installation. A loading test on the one hand gives an understanding of how much sulphur the carbon actually captures, while a kinetics test clarifies at what speed the breakthrough of H2S takes place. The information from these tests provides different information than the lab tests, because the measurements on site take place with a higher H2S level, a lower temperature and lower relative humidity. The results of the pilot tests were indeed positive: they showed a logical, expected relationship between the ‘on site’ data and the lab data.

The comparison between the pilot tests, the lab tests and the data from the customer itself provides essential information to determine the appropriate type of activated carbon, and to have a relevant discussion based on correct data. In the longer term these tests can be used to make adaptations to the composition of the activated carbon with varying biogas compositions. Thanks to the standardised implementation of the pilot tests, the results can also provide added value for other waste processing companies.