Biogas Safety first!

Specific requirements
It must be possible to operate gas flare systems sufficiently
reliably, for example independently of power
supply from the electricity grid (off-grid e.g. by battery,
emergency power supply or by other organisational
measures on the part of the operator), that the
release of unburned biogas is safely avoided. Gas
flare systems must be set up and positioned such
that no persons are endangered by gases, flames or
hot parts. The gas flare system should be erected in
such a way that the flame is blown away from the
gas storage tank, pressure relief devices, buildings
and public rights of way when the wind is from the
prevailing direction.
Gas flare
The exhaust gases from the gas flare must be discharged
above roof level with free outflow or via a
discharge pipe that must be at least 5 meters away
from buildings and public rights of way and must end
at least 3 meters above the ground.
other special operating states (widely fluctuating gas
storage fill levels). In automatic gas flare systems it is
recommended that a minimum cut-in pressure of 10
hPa (0,01 bar) should be ensured. If it is not possible
to achieve sufficient gas supply pressure upstream of
the gas flare system, appropriate equipment to rectify
this must be provided (e.g. gas pressure booster
blower, pressure-maintaining valve).
For emergencies and maintenance work outdoors the
gas supply to gas flare systems must be capable of
being shut off manually as close as possible to the
installation location of the consumption equipment.
The open and closed positions must be identifiable
or labelled.
Organisational protective measures
The gas flare should be checked for technical tightness
and for proper functioning of its safety and
monitoring equipment at regular intervals. The
manufacturer’s instructions for commissioning, operation
and maintenance should be followed.
Classification of Ex zones
The escape of gas to the surrounding area if the
flame is not burning is prevented by an automatic
shut-off device coupled with an automatically
actuated ignition device and flame monitoring
(auto ignitor). A suitable flame arrester is fitted
in the gas line upstream of the flare.
No zone necessary.
16. Requirements for process control system / instrumentation
and control (I&C) system
Technical protective measures
Control systems with safety functions must be designed
to be fail-safe, unless they are backed up by
a redundant system, for example a mechanical overpressure
protection device to protect against overpressure
or an overflow to protect against overfilling.
In the event of failure of the auxiliary power (electricity,
hydraulic or pneumatic supply to the biogas plant),
a safety shut-down or actuation of the emergency stop
switch, the plant or the relevant parts of the plant
must switch to a safe state. The safe state can be
achieved by means of control engineering measures,
hydraulic measures or mechanical measures.
Examples:
Closing of automatic gas valves outside the CHP
unit installation room
Switching off relevant gas compressors
Disconnecting all non-explosion-protected parts
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