The customer is a Company working in the field of wastewater treatment. It is well know that it is possible to produce biogas by aerobic or anaerobic "digestion", starting from various biodegradable materials. The gas obtained contains 60/70% of methane; this gas can be used to fuel the boiler required by the digester but also for electric generator engines.
At the same time an efficient logistic company must create reliable and precise report of the batch’s measurement data in order to satisfy the severe safety regulation and normative requirements. Here is why it’s so important to have a trustworthy data monitor system in this industry.
In order to optimize the operation, the customer needs to monitor and datalog the gas flow coming from the "bio-digester".
For example, immediately after feeding the digester there is usually a momentary strong gas production increasing, but also there are variations related to the season, where cold temperatures reduce the gas production.
Consequently, the feed rate controlling will improve the production process. The measurement of the produced and/or combusted methane is also generally required for certification purposes.
The customer requires also the capability to send alarms by SMS messages.
The proposed system is based on an industrial datalogger, plus two gas flow meter sensors.
Two key-points are the installation environment and the properties of the gas to be measured.
A datalogger with IP67 protection level is required due to the external installation: for this reason the selected datalogger is the NEXT Industries’ miniOMNIAlog model (151 mm x 136 mm x 90 ).
This compact instrument has an IP67 cabinet, and the internal electronic boards have complete conformal coating. Conformal coating - a layer of transparent plastic film - act as protection against moisture and other contaminants: the miniOmnialog can withstand in this way harsh environments, and also the high-precision measurement characteristics can be maintained in the long time.
This datalogger has a powerful 32-bit CPU, with two GB (4.000.000 measure) of internal non-volatile memory that provide a very long autonomous datalogging capability.
But the miniOmnialog electronic circuits are also designed to reduce the power supply requirements to the minimum: this device can work for some months (up to 12 months with 4 channels acquisition every day data sending) with one using the internal battery pack.
The alarm-generation capability required by the customer is fulfilled by the internal GPRS wireless modem: the system can be programmed to send SMS messages and/or ftp and/or emails based on the measured data. A relay output can also be activated in case of alarm.
Of course, this wireless connection is also able to transmit the measurement data, but it also possible to make a download using a simple USB key.
The gases are mainly methane and CO2, but also H2S and wet vapor are present, and this have corrosive effects: for this reason specific gas flow sensor have to be installed. We used two BFM mass flow meters: one on the digester ouput and one to measure the burned methane on the boiler.
Each of these flow meters has two 4-20 mA ouputs: one for the gas flow an another for the temperature. The flow meters are connected to the four 4-20 mA inputs of the miniOmnialog.
SMARTPHONE AND TABLET
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A moderm monitoring and datalogging system has been installed, with interesting measurement and communication features. Thanks to the cloud service- optional - you can Drag and drop widgets give you the power to configure and build custom dashboards that display critical information to empower effective decisions..
This will improve the overall behavior of the system and will payback in a short time.