Even operators of small size biogas plants use more and more portable biogas analyzer, in order to examine several times daily their gas composition and the main and post digester as well as in front of the CHP
As long as the substrate composition does not change substantially, 2-3 daily measurements are surely sufficient during normal operation periods. In this cases, the robust portable gas analyzer model GA-m with up to 7 gas analysis channels (CH4/ CO2/ O2/ H2S/ H2/ CO)is the solution. Optionally with biogas mass flow measurement in Nm³/h with optional insertion sensor (incl. flow correction based on actual gas composition).
However if substrate composition can change and/or if the biological process shall be continuously monitored, supervised and optimized, a stationary solution is preferred
The analyzer station COMBIMASS® GA-s Hybrid is a completely modular system and thus represents a simple and yet very effective solution for the online fermentation gas analysis. It is a system developed for high reliability, easy maintenance at site by the operator and further possible expandabilities.
The station gas COMBIMASS® GA-s Hybrid permits the users a higher flexibility compared with conventional online gas analysis systems. The pump and solenoid valves inside the cabinet enable a quasi-stationary analysis from different gas sampling points. Gas circles can be built up parallel, so various gas streams can be analyzed at the same time and continuously. Beside typical IR-technology and electrochemical sensors even paramagnetic and heat conductivity sensors can be used too. Data and alarms can be stored internally or transferred to the main PLC using various standard interfases, e.g. MODBUS, PROFIBUS, PROFINET, analog signals 4-20 mA and others. Further optional telecommunication modules can realize an external access to the data or can be used for functional tests and/ or maintenance diagnosis. An “alife”-signals can be sent via GSM/GPRS to a host server as an option. An uninterruptable power supply unit can keep analysis running and send out an alarm signal, even if normal power supply is interrupted.
Pressure and temperature of the inner cabinet and the gas streams are monitored. Additional modules for continuous control of operation and plausibility check can be supplied to increase manipulation-safety. The gas cells and modules can be recalibrated in the cabinet. So long-time accuracy of analysis is kept at a high level. Beside manual calibration mode also an auto-calibration mode is available. A hardware key or a software version with password functionality can be used to lock configuration settings.
In addition, for the economical operation of the fermentation plant it is likewise necessary to consider the gas composition and quantity of the individual digester stages. Therefore usually some biogas flow measurement is installed in the plant (e.g. in the generator container). Errors by varying gas pressure, gas temperature and gas composition are not compensated in most cases. While the gas composition (except during on and driving off phase) in liquid fermentation plants changes usually only very slowly over the day, the gas flow is subject to certain short term fluctuations, as they are caused for example by the agitator or different humidity content under variations in temperature. Therefore it is appropriate that at each digester a thermal mass flow meter is installed firmly and connected with the COMBIMASS GA-s Hybrid Analyzer.
Our COMBIMASS Eco bio+ biogas flow meter use the thermal principle and work also under most difficult conditions reliably, exactly and almost maintenance-free. The flow is determined directly as the standard flow rate, pressure and temperature compensation is not necessary. By other way, the COMBIMASS GA-s Hybrid does the automatic compensation of the gas flow signal by actual biogas composition and/or in-line humidity, calculating the dry gas flow if temperature probes or dewpoint sensors are Connected to the SPC of the analyzer.