GTS - Biogas Flares

These installations are usually carried out singly. In the event of malfunctions, maintenance and calamities of these utilization installations, the decrease in biogas will immediately stop. Because the production of the biogas cannot be stopped immediately, the biogas must be burned in a torch, because it may not be blown off in the air. The reason for this is that biogas mainly consists of methane (CH4) and carbonic acid (CO2), with methane being a stronger greenhouse gas compared to CO2. It is therefore better to convert the methane present in the biogas into CO2 through combustion.

These installations are usually carried out singly. In the event of malfunctions, maintenance and calamities of these utilization installations, the decrease in biogas will immediately stop. Because the production of the biogas cannot be stopped immediately, the biogas must be burned in a torch, because it may not be blown off in the air. The reason for this is that biogas mainly consists of methane (CH4) and carbonic acid (CO2), with methane being a stronger greenhouse gas compared to CO2. It is therefore better to convert the methane present in the biogas into CO2 through combustion.

GtS provides various types of flare installations. The 'Open Flare' and 'Closed ECO Flare' can be used for flaring biogas during disruptions, maintenance and calamities of the utilization installation. It is also possible that not all biogas can be used. For example, because the amount of sludge supplied is not always the same at WWTPs or because biogas production is slowly decreasing, such as at landfill sites, and it is not economically feasible to install a utilization installation for the maximum amount of biogas. In this case the flare installation must comply with the Dutch Emission Requirements (NeR). It states that the flare installations must meet the following requirements:

The outlet temperature must be at least 900 °C

The residence time of the combustion gases in the torch must be at least 0.3 seconds

The flare must be of the closed type.

The reason for this is that one wants to make sure that a complete combustion has taken place. In order to meet this requirement, the flare is equipped with an insulated chimney so that heat exchange with the environment takes place during the combustion process and no cold spots are created, so that complete combustion cannot take place.

In addition to these requirements from the NeR, the flare installation must also comply with NEN-EN-IEC 60079-10. In the Netherlands, a practical guideline has been drawn up on the basis of this standard, the NPR 7910-1 entitled 'Danger zone classification with regard to the risk of explosion'. It follows that the gas street gives zone 2 and only the space of 1 meter around the burner as a deviating area (AG) because a combustion takes place here. The main gas valve pressure switches and any quantity measurements are therefore carried out according to Atex.

Because the flares actually always have a calamity function, an important condition for the flares is that the flare installation remains operational in the event of a power failure. The GtS flares are equipped with a venturi burner and a low pressure pilot burner, so that low pre-pressures can be used and no compressor is required. A redundant power supply or emergency power supply by means of a battery can easily keep the main gas valve open and thus safely flare the biogas.

The capacities of the flares vary from 10 Nm3 / hr to 3300 Nm3 / hr, with the maximum size of the open flare and the closed ECO flare being 1000 Nm3 / hr.