Conditions of use
Whether the air dosing system can be used for desulfurization at a biogas plant or at a particular digester, must be cleared in any case with the manufacturer of the tank and the designer and constructor of the biogas plant.
- Due to the feeding of oxygen in the gas phase sulfur acid and sulfuric acid can form and cause high corrosivity, that even can attack stainless steel. Especially when the oxygen/air content is too high (>5%). Concrete must be protected by coatings or liners.
- If the biogas shell be upgraded to natural gas quality, air dosing must not be used, because nitrogen is difficult to remove.
- With substrates of high sulfur or H2S content in crude gas (>2.500 ppm) the air dosing is not sufficient enough for desulfurization.
- On digesters with small gas space and little settling area for the microorganisms the air dosing system is not sufficient.
- A biogas compatible non-return valve must be mounted directly onto the air nozzle in order to prevent gas flow backward into the air System.
- Check function of backflow preventer, and inspect valve for contamination every three months.
- Ensure to keep the orifice of the nozzle inside the digester in 2 m distance from agitators, windows and gas outlets.
- Install the device in outdoor protected from rain and snow or in well ventilated rooms with dry and clean air.
- Compare the daily quantity of gas, and check the airflow in accordance with the table.
- At unchecked air feeding and extreme reduction of gas production an explosive mixture can occur in the digester
- The pumping unit should be place outside, protected from rain and snow or in a well ventilated room with clean and dry air.
Air inlet station
Mounting at comfortable operating and reading height
Flowmeter must be in a vertical position
Always keep out of Ex zones and protected from moisture
If possible install in rooms that are dry and have clean air supply
Do not install in closed spaces and only in well ventilated places
In an easily accessible position for maintenance purposes with clearance to the sides and rear. For cleaning purposes the compression fitting can be taken from the stainless steel tube to allow the stainless steel spout when contaminated to be freed easily using a rod (e.g. threaded rod).
Always keep the tip of the nozzle in the gas space above the maximum liquid level
Assembly on concrete wall with ø15 -16 mm bored holes, stainless steel tube using building adhesive
The air inlet station may only be operated in conjunction with a biogas suitable gas non-return valve mounted to each air nozzle directly at the digester, so that in case of pump failure or air leaks in the system no gas can escape. Daily balance of the amount of gas produced and the required amount of air.