In a biogas plant, microorganisms biologically degradate the organic starting substances (substrate) under exclusion of light and oxygen. The product of this anaerobic degradation is a gas mixture which primarily consists of methane. This gas mixture is called biogas.
The experimental plant it serves to demonstrate the generation of biogas in a practical manner. The substrate is a suspension of shredded organic solids. It is hydrolysed and acidified in the first stirred tank reactor. Here, anaerobic microorganisms convert the long-chain organic substances into short-chain organic substances. The biogas forms in the second stirred tank reactor in the last step of the anaerobic degradation. It contains mainly methane and carbon dioxide. This two-stage method enables the ambient conditions to be adjusted and optimised in both reactors separately. The digestate is collected in a separate tank.
Learning Objectives/Experiments
- Achieving a stable operating state
- Influence of the following parameters on the biogas generation
- Temperature
- Substrate
- Volumetric loading
- pH value
- Influence of the operation mode on the biogas yield
- Single stage or dual stage
- With and without post-fermentation
- Continuous and discontinuous
- Determining the following parameters depending on the operating conditions
- Biogas yield
- Biogas flow rate
- Biogas quality
Specification
- Two-stage biogas plant (continuous or discontinuous operation possible)
- 2 stirred tank reactors made of stainless steel with capacitive level sensors
- Separate supply unit with substrate tank and feed pump
- Control of temperature and pH value in the reactors
- 2 metering pumps for acid and caustic
- Heating water circuit with tank, heater, temperature controller and pump
- Biogas is dried with silica gel
- Biogas analysis: flow rate, methane content, carbon dioxide content, humidity and temperature
- Control of the experimental plant using a PLC, operated by touch screen
Technical Data
- Tanks made of stainless steel
- reactor (stage 1): approx. 20L
- reactor (stage 2): approx. 70L
- substrate tank: approx. 25L
- digestate tank: approx. 25L
Pumps
- 3 peristaltic pumps: each max. 25L/h
- 2 metering pumps: each max. 2,1L/h
- heating water pump: max. 480L/h
- Stirring machines
- substrate tank: max. 200min-1
- reactors: each max. 120min-1
Measuring Ranges
- methane content: 0…100%,
- carbon dioxide content: 0…100%
- flow rate: 0…30NL/h (biogas)
- pH value: 2x 1…14
- humidity: 0…100%
- temperature: 3x 0…100°C (reactors and biogas)
- 400V, 50Hz, 3 phases
- 400V, 60Hz, 3 phases; 230V, 60Hz, 3 phases
