The Importance of Biogas Process Analysis (Part 1 – Biogas Analysis)
In recent years we have seen a rapid development of biogas plants, nowadays there are about a thousand active plants throughout the Italian territory. The strong growth has occurred thanks to many subsidies granted by European community to landowners who wish to make use of agricultural waste to produce energy. The energy can be used to support their needs (equipments, heating etc.) or those of others – in fact they have the possibility to market the energy produced and get subsidies.
Currently things changed from landowners built their first plants. This is due to the introduction of more stringent regulations that grant incentives only to the more virtuous plants. The owners are now obliged to fully optimize their plants in order to gain incentives.
How does (shortly) a biogas plant works?
As already mentioned the scope of a biogas plant is to use agricultural waste, fodder or landfill to produce energy. In the first phase these components are mixed together – following some recipes – and than used to feed the digester where the anaerobic digestion process will take place, i.e. the solid biomass is transformed into a mix of sewage and gas.
The biogas plant plays the main job during the anaerobic digestion process: a biological process during which – in the absence of oxygen – organic compounds are converted in solid, liquid and gas solutions. The gaseous compounds created are: oxygen (O2), carbon dioxide (CO2), methane (CH4), hydrogen (H2) and hydrogen sulfide (H2S): the so called biogas.
The biological process consists in four additional steps (hydrolysis of biomass, acidogenesis, acetogenesis and methanogenesis) in which the success or failure of one prejudice the result of the subsequent step. The way all these phases are completed involves the production of biogas and therefore the achievement – or not – of the subsidies.
It is important to carry out a double-checking: the gas produced (biogas analysis) and the chemical and physical parameters (liquid analysis).
Let’s start from the first:
Biogas analysis
The biogas is a mix of compounds and each of them requires a specific sensor with a specific technology to be measured. In addition the biogas includes corrosive gases, such as hydrogen sulfide, that requires a specific gas treatment which can make the gas visible to each sensor without causing damages.
APT offers two biogas analyzers (AWIECO and AwiFLEX) able to satisfy each type of plant, from the smallest to the largest.
Both analyzers use the following technologies:
| GAS | TECNOLOGIA |
| Oxygen (O2) | Electrochmical / Paramagnetic |
| Carbon Dioxyde (CO2) | Infrared |
| Methane (CH4) | Infrared |
| Hydrogen (H2) | Electrochemical |
| Hydrogen Sulphide (H2S) | Electrochemical |
What are differences between the two models?
AwiECO
It is the most economical and compact solution that enables measurement up to 3 gases in a single sample point. It provides a spot measurement (maximum 50 per day) and is supplied with the 4-20 mA interface as standard. Ideal for biogas plants up to 150kW.
To have more info please click here.
AwiFLEX
It is a more professional product suitable to monitor the biogas analysis up to 9 points with the possibility of continuous analysis. This version is equipped with an internal cooling to cool down the sample.
To have more info please click here
With both versions you can make the remote control monitoring and managing the analyzer remotely. You just need a broadband connection in the plant and through any device (including smartphones and tablets) you can check the operations, gas values, and view any errors or faults.
The desulphurisation
In a biogas plant is also important to manage the desulphurization i.e. the process of removal the hydrogen sulphide turning it into elemental sulfur and water.
The concentration of H2S in an anaerobic process may reach up to 2,000 or 3,000 ppm. When biogas is burned to produce energy the level of H2S decreases producing sulfuric acid which can cause corrosion in the engine increasing the costs of maintenance.
One of the most common ways to reduce the concentration of H2S is to use iron chloride in the digester by converting H2S into iron sulphide. Although this process is very efficient it requires several control functions with dedicated pumps and storage containers, this entails related operating costs that are not negligible.
The desulfurization systems offered by APT is AwiDesulph an automatically controlled system driven by the analyzer that avoid any manual control and enters just the right amount of air in the process. It has no operating costs and thanks to the easy access at the analyzer it uses the memory and interfaces to adjust the parameters remotely.
To have more information on AwiDesulph just click here.
On the second part of this article we will explain the liquid analysis in in a biogas plant and how it helps to optimize the process.
If you are interested and wish to receive information of the above mentioned products just contact us and an expert will get in touch with you shortly.
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