Sphere Double Membrane Biogas Holder
Brief introduction of sphere double membrane biogas holder
The Mondes sphere double membrane biogas holder is a durable air supported structure specifically designed for the purpose of biogas storage. Typically, the biogas holder is installed as part of the anaerobic digestion system in a wastewater treatment plant, agricultural digestion schemes, landfill sites and combined heat-and-power plants that use digested organic materials to generate biogas as an energy source.
Typical Installation of sphere double membrane biogas holder
The biogas holder is installed between the digester and the gas consumption equipment: A Typical Gas-Holder installation is designed to store approximately 20 hours worth of gas production volume. Storage volumes can be designed to suit the process production and consumption requirements; Smaller units may be required as a buffer storage on a continuously operated plant, but larger gas storage units may be specified to hold the gas for use during the local peak-power requirement period, when energy produced can be sold on at a better price.
The Sphere Double Membrane Biogas Holder: OUTER MEMBRANE
The Biogas Holder structure comprises two spherically shaped membranes and a flat bottom membrane mounted onto a concrete base slab.
The outer membrane is designed to all appropriate international codes for air-supported structures. The textile membrane is designed to withstand the internal air pressure forces as well as external dynamic forces from wind and snow. Mondes Green Technology uses a range of membrane materials of up to 6,500 N/5cm breaking strain – the strongest textile membrane currently commercially available. The membranes are manufactured from polyester yarn with a PVC coating. The coating is applied to our own specifications with additives and treatments for protection against sulphur and other components found in biogas. The membrane is specified for a low methane permeability of 250cm³/m²*24h*bar pressure. The external membrane receives additional additives for increased protection against Ultra Violet radiation. Typical life expectancy of the external membrane is 20 years in an exposed, high-UV location. Longer durations can be expected in countries where UV levels are reduced. Over the lifetime of the structure, the outer membrane will become embrittled and begin to crack up, exposing the polyester yarns. At the end of its lifespan, the outer membrane can be easily replaced. Inner membranes (see later discussion) do not suffer from the same UV aging process and will outlast the outer membrane by a minimum factor of 2:1. Each roll of membrane material is 100% tested by both computer and human visual inspection techniques.
The Sphere Double Membrane Biogas Holder: INNER MEMBRANE
The inner membrane forms the variable volume gas containment within the outer membrane. The inner membrane and bottom membranes are sealed with a gas-tight compression seal around the periphery of the structure on the concrete base. As the volume of stored gas increases, the inner membrane rises to accommodate it. The pressure within the gas containment, and therefore the gas pipelines, is maintained by the air pressure within the outer membrane bearing on the surface of the inner membrane. The pressure differential across the outer air containment and inner gas containment is minimal – due only to the weight of the inner membrane (the gas containment pressure is 0.8 to 1.5 mBar higher).
The inner membrane is made from the same textile fabric as the outer membrane. The inner membrane has reduced UV protection because it is not exposed to this radiation, but has an additional anti-static coating to eliminate the possibility of static being caused by the movement of the membrane during operation. Despite the unstressed service condition of the inner membrane, it is always specified to be the same strength as the outer membrane. In the unlikely even of an outside membrane failure, the inner membrane will maintain structural integrity against all loading conditions (internal pressure and environmental).
Pricing of free standing double membrane biogas holder
Pricing varies depending on capacity required, operating pressure and gas production and utilization rates. Quotations are provided within 48 hours of request when accompanied by minimum required specification data.
Minimum specification data required in order to provide a quote:
- Required Gas Storage Capacity (m³)
- Operating Pressure (Kpa or mbar)
- Gas Production & Utilization rates (m³/hr)
