Biogas production plant - WASTEPOWER
Code:Anaerobic digester for biogas and electrical energy production from organic fraction of municipal solid waste (O.F.M.S.W.).
DESCRIPTION OF THE PROCESS
The Wastepower plant is based on wet anaerobic digestion of input materials, where organic substances are degraded by microorganisms in the absence of oxygen (anaerobic condition) at a temperature of approx. 35°-37°C (mesophil process) or at 50°-55°C (thermophilic process).
The input biomass (derived from farming and agriculture) is pumped into a pre-treatment area to make a particular organic liquid mixture. The mixture then passes to a high-concentration, wet digestion process.
The main sub-products of anaerobic digestion are biogas and digestate. Biogas is a gaseous mixture mainly composed of methane and carbon dioxide, and is suitable for the combined production of electrical and thermal energy. Digestate is the output sludge resulting from anaerobic digestion, and is separated into two fractions: a solid one and a liquid one.
DESCRIPTION OF THE PLANT
The input material is sent to a high-efficiency pre-treatment area for grinding and mixing.
A dedicated PLC-based software allows to constantly monitor the quantity of organic material and raw materials needed to ensure high-quality biogas production.
Anaerobic digestion for biogas production
The output biomass passes to a high-efficiency anaerobic digestion area, where the organic material is degraded and gas is produced under constantly controlled mixing and temperature conditions.
The anaerobic digestion process takes place inside digester. Sludge mixing in the digesters is granted by specifically designed mixers to guarantee that the liquid fraction is adequately mixed even at high concentration levels.
Process temperature is controlled through special tubular heat exchangers using the cooling water of the combustion engine inside the cogeneration units.
The output biogas contains approximately 55-60% of methane, which is stored inside gasometers located on the top of the digesters, including gasometric membranes of different volume.
The plant also includes a biogas organic desulphurization system inside the anaerobic digester with oxygen concentration control.
The output gas is then sent to a cogeneration unit for the combined kickback of electrical and thermal energy. The cogeneration unit is composed of an endothermal engine directly coupled with a power unit.
Output energy, the output of which is equal to 38-42% of input energy, is channeled through a transformation chamber to the national network. Thermal energy is recovered from the engine cooling cycle: it is in part used to heat the digesters and in part stored for other purposes.
Separation of digested solid and liquid fractions
The output product deriving from the digestion process is sent to a revolving separator, the purpose of which is to separate the liquid fraction and the solid fraction. The liquid fraction can be stored in specifically designed tanks or sent to treatment or disposal. The solid fraction can be piled on concrete flooring. They can also be spread over land during the appropriate period. For the most part, liquid fraction is re-sent to the pre-treatment area; remaining is re-used in the composting section or sent to the depuration treatment.
Controller, process control and supervision system
The entire process is controlled through a centralised measurement and regulation unit and an automated supervision and process control system. This equipment is installed in a centralised technical room, easily accessible to facilitate supervision, control and maintenance operations.
Energy generated from biomass, leading to the release of green certificates, represents a new and highly efficient SOURCE OF INCOME. GREEN CERTIFICATES grant a short-term economic return and 15 years of proven plant duration.
The INVESTMENT is commensurate with plant profitability. The INVESTMENT is safe because traditional energy sources will gradually deplete and the need for energy generated from renewable sources will proportionally increase.
Energy generated from anaerobic digestion is considered BIOENERGY.
Biogas is considered a low environmental impact energy source.
INPUT ORGANIC WASTE
• organic waste
• fruit and vegetable waste
• food and farm waste
• canteen waste
• butcher waste
• seafood processing waste
• general farm waste
• bovine manure
• pig manure
• horse manure
• goat manure
• ovine manure
• chicken manure