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To measure biogas flow rate, Vortex flow meter or Thermal mass flow meter, how to choose?

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Update time : 2019-05-26 17:28:07


What flow meters can be used for measuring biogas? Before that let’s talk about why we need to measure biogas and what’s the difficulty to measure biogas.


The application for biogas measurement:

1), Provide reference data for biogas stations;

2), Detect the efficiency of fermentation tank: The efficiency of the fermentation tank can be known by the flow of biogas. If the flow fluctuates unexpectedly, the situation of the fermentation tank can be checked in time;

3), Control the combustion efficiency of the boiler: When the biogas boiler burns, it is necessary to understand the flow of biogas so as to control the ventilation of the boiler. Excessive ventilation will reduce the furnace temperature; too low ventilation will cause waste and pollution;

4), Control greenhouse gas emissions: CH4 and CO2 in biogas are both greenhouse gases.


The difficulties for biogas measurement:

1), Very low pressure: The pressure for raw biogas from fermentation tanks usually does not exceed 10kPa

2), Component change: Biogas is composed of a variety of mixed gases, and the composition of biogas produced will vary greatly with different raw materials.

3), Large flow fluctuation: with the change of raw materials, bacteria, temperature fluctuation, and other conditions, the output of biogas flow will also change greatly, so a larger range ratio of flowmeters is required.

4), Moisture vapor: Biogas is produced by fermentation of biomass. Water in biomass is brought into biogas, so it usually contains saturated water vapor.

5), Corrosive: Biogas usually contains H2S, although the content is low, H2S will form corrosive acid when it encounters water vapor, which has a greater potential for corrosion on metering elements.
 

Based on the information above, we can find that demanding measuring parameters associated with biogas applications are a challenge. Several technologies are available, including mechanical, thermal mass, and vortex.


The mechanical flow meter is a traditional method to measure the biogas with lower cost and compact design. The disadvantage is that mechanical flow meter has a large pressure drop and low turndown ration, obviously, it’s not very suitable in biogas industrial nowadays.
 

Thermal mass flow meter has been widely used for gas measurement with the advantages of direct mass flow rate measurement, without pressure drop and wide range ratio. The problem, however, with using thermal mass flow metering for biogas is that the gas is wet; when water is introduced, it skews the results, creating the possibility of large measurement errors.
 

Vortex flowmeter has been more successful. The measurement results will not be influenced by the gas components and vapor contained in the medium. But the low pressure and low velocity of biogas make most of the vortex type meters can’t take the job.
 

As noted, it seems that there is not a perfect flow meter for biogas measurement, so please provide the detailed parameters (including but not limited to the following parameters) for our evaluation, we will provide a suitable solution for you.
 

- The component of the biogas

- Working temperature

- Working pressure

- Pipe size

- Flow rate including min flow, normal flow, and max flow
 

Please reach us at sales@mega-meter.com for more information. We can share with you the product catalog and quick start guide for both thermal mass flow meter and vortex flow meter.

You can also check Thermal Mass Flow Meter or Vortex Fow Meter for more information.

Thank you for your time.