Biogas upgrading
Compact system solution for efficient biogas upgrading
Limited space, short construction time, high yield: With the agriPure SMART, you ensure maximum methane purity with minimal effort.
- 130-295 Nm³/h raw biogas on minimum surface area
- Complete treatment system in a single container
- Pre-assembled modules reduce costs
- EVONIK membranes for maximum methane purity
The technology in detail: Efficiency through proven membrane technology
At the heart of our biogas upgrading system is EVONIK’s proven 3-stage membrane technology. These highly selective SEPURAN® Green membranes efficiently separate methane from carbon dioxide and other gases. The result is an impressive methane yield of up to 99.4% and a biomethane purity of over 97%. This high-quality biomethane can be fed directly into the natural gas grid or used as a climate-friendly fuel (Bio-CNG/Bio-LNG).
The innovative 3-stage process of our biogas upgrading minimizes methane slip and optimizes energy consumption, resulting in low operating costs and high plant efficiency. A sophisticated heat recovery system also uses the waste heat from the compressor and the gas cooling system to further reduce the plant’s own energy requirements.
The biogas upgrading process steps at a glance:
Pre-treatment of the raw gas
The upgrading of biogas to biomethane in a biogas upgrading plant begins with thorough pre-treatment. In the first step, condensation drying, the raw biogas is cooled down considerably in order to condense the water it contains. The water is then drained via a siphon. This module includes a shell-and-tube heat exchanger made of V4A stainless steel, a membrane expansion tank and a filter for the chiller. The externally installed chiller supplies the cold water required for this process. After drying, a flow meter measures the exact volume of the processed raw gas before it is fed into the next stages.
Compression and desulphurization
After drying, the biogas treatment process moves into the pre-compression phase, during which the pressure and temperature of the biogas are increased. This increase in pressure not only boosts the efficiency of the subsequent main compressor but also optimizes the performance of the activated carbon filter. In this special vessel, the biogas is desulfurized, with an initial charge of potassium hydroxide-impregnated activated carbon already in place. Subsequently, a single-stage, oil-lubricated screw compressor compresses the gas to the pressure required for the membrane separation stage. All safety-related components, such as pressure relief valves and an oil separator, are integrated, while the control cabinet is safely installed outside the ex-zone.
Core process: Membrane separation to produce biomethane
The heart of the biomethane plant is the multi-stage membrane separation for the production of high-purity biomethane. The high-pressure gas plant and the modules for CO2 separation are housed in a thermally insulated steel container. After the main compression, the compressed gas is freed from residual water and oil by cooling and coalescence filters in order to ensure the purity required for the membranes and to achieve a residual oil content of less than 0.01 mg/m³. The membranes separate the methane from the CO2 in a three-stage process. The finished biomethane leaves the second stage with a low pressure loss and is ready to be fed into the grid.
Efficient vapor recovery and system integration
To maximize efficiency, the CO2-rich gas produced during separation in stage 2 and the methane-rich gas from fine purification (stage 3) are recirculated and passed through the process again. This internal gas recirculation ensures that, during normal operation, approximately 40% of the raw biogas throughput is recirculated, thereby minimizing methane losses. The CO2 from stages 1 and 3 is released into the atmosphere at virtually no pressure. The entire system is integrated as a compact unit in a container which, in addition to the membranes, also includes all pipelines, separators, measuring instruments and sensors required for the safe and automated operation of the biomethane plant.
Product photos: Plant for biogas treatment
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