KEY FEATURES
LOW PRESSURE OPERATION
LOW MEMBRANE STRESS
THREE PLY HIGH TECH MEMBRANE
ODOUR COMPLAINTS REDUCED
NO AIR BLOWERS TO FAIL
NO HEIGHT GAUGES TO FAIL
PRESSURE-BASED CONTROLS - 100% OF BAG VOLUME IS USED
HARD DOME - GRP WITH VANDAL RESISTANCE
CAN BE INTEGRATED TO A VARIABLE ORIFICE FLARE FOR STATE OF THE ART ODOUR CONTROL
REF DRAWING NO. 100512/ISSUE 6
These storage bag systems provide overnight wet biogas storage without the need for prior gas scrubbing or gas compression. Our gas bags have no moving parts except the variable volume membrane. There are no motors to compress the gas and the low pressure regime provides very low stress on components for long life. This all adds up to RELIABILITY.
The gas is normally extracted from the storage dome by means of one of our biogas boosters to provide pipeline pressures between the bag and the boiler/chp unit. This enables the digester and gas bag to be operated at ultra low gas pressures. The digester pressure control system may be based around the unique Practically Green fail safe manometer set to operate at Atmospheric +3 to +6 mm (1/8 - 1/4 inch) of water gauge. Operating a digester in this mode greatly reduces leaks of valuable methane from cracks and broken seals and provides safe operation. We have over 25 manometer/years of experience with this unit and it has worked without fault!
The termination point for the contract is the ABS pipe ( 6inches/150mm dia.) projecting from the base of the bag about 0.5 meters.
The Site requirement for a GRP base is a flat area exceeding the diameter of the base with a 24 inch (600mm ) deep trench to the circumference of the base from the centre of the bag to take the outlet pipe below frost level. Levels should be such that gas pipes are never horizontal but fall to a water trap or away from a water trap to avoid blockage by standing water. A fall of 1:20 should be assumed for the water surface. Water traps should be built above any (Winter )water table and below frost levels in soil.
These bags may be deflated or lost in storm winds unless protected. A wooden fence with vertical boards will suffice if built up to the height of the bag. Leave 1-3 cm gaps between wooden slats to prevent turbulence over the bag. Preferably use the optional GRP protection dome.
The maximum pressure limit for these bags has not been ascertained but they are normally operated at a maximum of 3mm water gauge - a light lid over a water trap somewhere in the line to the digester is an essential component in the construction of a gas retaining system. The lid should relieve pressure at 6mm WG.
The bags are guaranteed for one year against faulty workmanship and materials defects but not against storm damage, or accidental damage during use. However, the design is the result of over 12 years field trials and should last 6-7 years before easy repair, possibly longer (our mistakes were all made on the early units!! ) The bag material is a very advanced three phase polymeric laminate, H2S resistant on the inside layer, fibre reinforced to provide extremely high flexural strength. The outer layer is resistant to UV degradation.
Sizes [hemispherical domes]
For further information, email me at les.gornall@dial.pipex.com
This page created with Netscape Navigator Gold and Adobe Pagemill