GAS FLARES
   
 
   
Fackel KA Köln-Stammheim 2200 m³
GAS FLARES FOR DIGESTER GAS/BIOGAS

FUNCTION

The gas flares have the task of burning digester gas if an utilisation by the combined heat and power unit or the heating is not available. The flares have to ensure that no unburned gas will be blown into the atmosphere. Thus hazards for humans and the environment are avoided.


CONSTRUCTION

The gas flare is composed of a flare burner and a flare substructure. It is designed according to the principle of an injection burner and consists of a nozzle, an injector with an air flow regulation, a flame protection tube, a fitting group and a flare control system. The gas flare is totally made out of stainless steel, whereas gas contacting parts are done in stainless steel AISI 316 Ti.

The flare burner is made up of the flame protection tube, the injector and its supporting structure, the ignition and the flame monitoring. The flame protection tube and the injector are made out of stainless steel AISI 309.

The flare substructure bears the flare burner and takes up the vertically installed fitting group. On demand it is able to provide it with a sheet-metal covering for protecting the fittings from the weather. Then a door enables a good accessibility.

The fitting group consists of a magnetic or motor-driven valve (slow opening, fast closing,
de-energised closed), a flame arrester and two pressure switches.

The flare control system is fitted in a control cabinet out of stainless steel that is mounted on the flare substructure. The internal wiring to the fitting group, the ignition and the flame monitoring is completely done before delivery.



MODE OF OPERATION

Surplus gas is able to be burnt off by the flare once an adequate signal sets the flare into operation. Normally this signal is provided by the filling level indication of the gas holder. If the gas holder reaches its maximum filling level, the starting signal for the gas flare will be released.

Then the flare control system initiates the ignition and opens the magnetic or motor-driven valve. The gas is now able to run through the valve and the flame arrester and is discharged with a high exit speed into the injector by the nozzle.

Caused by the high speed of the gas the necessary combustion air is sucked into the injector from outside and a combustible gas/air mixture forms. Leaving the injector this mixture is ignited by an ignition electrode and burns off inside the flame protection tube. This tube provides a wind protection for a colourless burning flame.

Once the gas has been ignited and a steady flame has been established the flare will burn until the filling level indication of the gas holder will send a shut-down signal. Then the magnetic or motor-driven valve will close and the burning process will be finished. An automatic restart of the gas flare will take place as soon as the starting condition, i.e. the maximum filling level of the gas holder, is fulfilled again.

As an alternative to the filling level indication of the gas holder, the fluctuating gas pressure in the gas system can be used for switching the gas flare on and off. For this purpose there are two pressure switches available to adjust a maximum and minimum pressure as switch-on and shut-down value.

The control cabinet contains the whole control system for the flame monitoring and the ignition of the flare. An ignition transformer feeds the ignition electrode that directly ignites the exhausting gas/air mixture at the injector. The combustion is monitored by an ionisation electrode that controls the ionisation current produced by the flame. If this ionisation current breaks down at a failure of the flame, it will be detected by the ionisation electrode and a
re-ignition will be initiated by the automatic firing device. In case of a long running failure of the flame the gas supply will be interrupted and a malfunction message will be displayed.