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Websites with more comprehensive Glossaries are provided by Return to Other Resources or Homepage DEFINITION OF TERMS From Whessoe Varec Product Catalogue 1996 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Microorganisms that live and reproduce in an environment containing no "free" or dissolved oxygen. Used for anaerobic digestion. Anaerobic Digestion Decomposition process using microorganisms to stabilize organic solids or biosolids. This process generates biogas. Biochemical Oxygen Demand (BOD) Rate of oxygen utilized by wastewater under controlled conditions of temperature and time. Biogas By-product of anaerobic digestion. A saturated gas consisting of approximately 55 to 70% methane, 25 to 35% carbon dioxide, and trace amounts of nitrogen and hydrogen sulfide. Biosolids Old term used was "Sludge". It is the waste material from animal or vegetable sources. Waste contains mainly carbon and hydrogen. A device to prevent the reversal of gas flow. Chemical Oxygen Demand (COD) Amount of oxygen from potassium dichromate required to chemically oxidize wastewater. Cogeneration Gas-driven turbines produce heat in the process of generating electricity. The heat is fed to generators that produce steam. This steam is used to generate more electricity. Complete Combustion Products arising from the combustible elements carbon, hydrogen, and sulfur. May include nitrogen brought in with the air and oxygen in excess of air. The products of complete combustion are principally C02, H20, S02, N2, and 02. Usually, the presence of CO indicates incomplete combustion. Condensate and Sediment Trap Device used to remove liquid and solids entrapped in the biogas. Pressure or vacuum relief setting is achieved by loading properly weighted discs on top of pallet or disc in a valve. Design Pressure Maximum Pressure above which tank or piping may sustain structural damage or fatigue. Diaphragm Thin, flexible disc that moves in response to changes in pressure. Digester Tank used to contain biosolids during the anaerobic digestion process. Differential Pressure Difference between inlet pressure and outlet pressure of a device. Downstream In the direction of the gas flow. Drip Trap Device used to safely remove accumulated condensate from gas piping without interrupting gas flow. Chemical reaction that releases energy in the form of heat. May cause an increase in temperature. Explosive Range A mixture of gas and oxygen capable of combustion.(Note - 5%-15% for Methane) Extensible Can be extended. A flame arrester bank frame is referred to as "extensible" because the frame can slide apart providing access to individual bank sheets. A device that prevents flame propagation. Flame Check Similar function as a flame arrester, except it is used in smaller diameter lines with low gas flows. Flame Propagation A flammable mixture from ignition source spreads through the gas pipe train starting at low flows and increases in speed as it travels through a long pipe run. Flame Trap Assembly An assembly consisting of a flame arrester and a thermal shut-off valve.
Gas Purifier A device that removes H2S from biogas. Gas Storage Holder Low-pressure gas holder or high-pressure sphere used to maintain uniform gas system pressure during periods of varying biogas production or consumption. Gas Utilization Biogas may be burned as fuel by engine generators to produce electrical power for the plant. Heat recovered from the engine coolant and exhaust provides heating for the plant and the digesters. Biogas-fired boilers may be provided for supplemental heat when necessary. A flammable, highly poisonous gas having an unpleasant odor. Minimum temperature required that initiates or causes self-sustained combustion. By-product of the natural decomposition process occurring at a landfill. Comprised of 50 to 60% methane, 40 to 50% carbon dioxide, and less than 1- percent hydrogen, oxygen, nitrogen, and other trace gases. LEL (Lower Explosive Limit) Minimum concentration of gas vapor in air or oxygen where propagation of flame does not occur on contact with a source of ignition. Piece of land where household waste and/or treated domestic sewage biosolids are disposed. Total surface area of passageways permitting flow through a flame arrester bank. Pressure of the gas system or digester during normal operation. Overpressure The amount of pressure above the desired pressure setting necessary to relieve full flow capacity. Oxidation The addition of oxygen, removal of hydrogen, or the removal of electrons from an element or compound. A disc or round plate that fits over a valve seat port opening. pH An expression of the intensity of the alkaline or acidic strength of water. Values range from 0-14, where 0 is most acid, 14 most alkaline, and 7 neutral. Pressure Drop (Head Loss) Difference between inlet pressure and outlet pressure of a device. Also, loss of pressure through a length of pipe. Pressure Relief Valve A valve which opens upon rising inlet pressure. Pressure and Vacuum Relief Valve A device for the relief of excess pressure or vacuum on the digester or gas holder cover. A device which controls either valve upstream or downstream pressure. Small access cover installed on digester or gas holder roof, which allows sampling of contents. Sanitary Landfill A landfill permitted to accept household and commercial waste (solid and liquid non-hazardous waste). Saturated Gas Gas containing maximum water vapor for a given pressure and temperature. If more water vapor is added to the gas stream, or the pressure increases or temperature drops, condensation will occur. Seat Insert A soft material which improves the seal between the valve cover and seat, or pallet and seat ring. Seat Ring The part of a valve where the pallet rests and allows for gas-tight sealing. Sediment Solid particles entrapped in the biogas stream. Sludge Biosolids separated from liquids during processing. May contain up to 97% water by volume. Specific Gravity The ratio of the density of a particular gas to that of air. Spring Loaded Valve relief setting achieved by properly compressing a spring against the top of the pallet. Stoichiometric Pilot A pilot having a perfect theoretical fuel to air ratio. A valve that immediately shuts-off gas flow when the fusible element is subjected to excessive heat. In the opposite direction of the gas flow. Waste Gas Burner A device that safely combusts biogas. Return to Other Resources or Homepage |
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© 2009 The University of Adelaide Last Modified 25/11/2009 Biogas CRICOS Provider Number 00123M |
