CO2 Absorption Bottle

Application

RITTER has developed a CO₂ absorption bottle which reliably absorbs more than 99% of CO₂ from biogas. Guaranteed! Without any indicator liquid for absorption limit! This absorption bottle combined with the »RITTER Biogas Batch Fermentation System« provides the ideal solution for professional biogas research.

Operating Principle

The biogas generated in the fermentation bottles flows through a dip pipe into the absorption bottle (“bubbler”) containing the absorption solution. Due to the unique dip pipe design RITTER guarantees a CO₂ absorption rate of at least 99% up to reaching the absorption capacity limit. This capacity limit will be indicated by the MilliGascounter by measuring the volume of methane remaining in the gas stream after absorbing the CO₂.

The high CO₂ absorption rate is achieved as a result of …

• the large wetting surface of the biogas within the absorption liquid.
• the long holding time of the CO₂ inside of dip pipe chamber.

Due to this design, the absorption capacity of the RITTER CO₂ absorption bottle is far superior to that of absorption bottles with surface absorption as the following diagram shows:

Technical Specifications

Dimensions absorption bottle (»bubbler«)	Volume 250 ml Wide mouth GL80 with screw cap ø D 95 mm x H 106 mm
Material	Borosilicate glass
Dip pipe chamber volume	8.3 ml
Holding time of CO2 bubble in dip pipe chamber	dependent on gas flow rate
Absorption solution	3-molar caustic potash solution (KOH 3 mol/ltr in aqua dest.)
Gas in/outlet ports	PVDF screw-type tube connection for tube Ø 4i / 6o mm

Absorption Capacity

Definition:

Table of absorption capacities at various flow rates and CO₂ concentrations: ⁽¹⁾

⁽¹⁾ The table will subsequently be updated with data of additional CO₂ concentration values. For determination of the CO₂ concentration value the gas analyser »RITTER MultiGas« is recommended. With the dual version, the concentration value for Methane can be determined simultaneously as well. If no determination of the CO₂ concentration value is possible, it is recommended to use the smallest amount of CO₂ concentrations stated in the above table.
⁽²⁾ Per bottle filling 250 ml, absorption solution KOH 3 mol
⁽³⁾ After the CO₂ was absorbed from the biogas, the MilliGascounter displays the volume of the pure methane. The CO₂ absorption capacity limit is reached when the MilliGascounter indicates the values the stated in the table above.
Please note: The values for the max. volume of methane stated at a specific flow rate were obtained at a constant flow rate of biogas. However, with biogas fermentation processes the flow rate varies in general significantly during a fermentation test run. In order to get a more meaningful value for the remaining CO₂ absorption capacity the use of the data acquisition software »RIGAMO« is highly recommended.

Calculation of Absorption Capacity with Data Acquisition Software »RIGAMO«

The table above shows that the absorption capacity with the RITTER absorption bottle …

• does not vary very much with different concentrations of CO₂.
• varies significantly with increasing flow rates because of the decreasing time the CO₂ is in contact with the absorption liquid. However, due to the unique dip pipe design RITTER this time is far higher than with usual surface absorption bottles.

The following diagram shows the CO₂ absorption capacity as a function of the flow rate:

Features of the software:

• Calculation of remaining CO₂ absorption capacity by regression curves at actual flow rates and with different CO₂ concentrations.
• Display of remaining CO₂ absorption capacity in real time for each absorption bottle.
• Storage of remaining CO₂ absorption capacities for each bottle at the end of the fermentation process so that the remaining absorption capacity can be used for following fermentation processes.
• Setting of an individual value of remaining CO₂ absorption capacity for giving an alarm when approaching the pre-set level of remaining CO₂ absorption capacity.