GB2530571A - Gas analysis device - Google Patents

Abstract

A device 1 for use with a biogas volume-measuring system (10) having a biogas outlet valve arranged to open and thereby release biogas into a liquid reservoir, device 1 comprising a housing defining a chamber having an inlet and an outlet 2. The inlet receives the biogas outlet valve such that when the biogas outlet valve is open gas is released into the chamber. The housing is submergible in the liquid reservoir. Outlet 2 is arranged above the inlet when the biogas outlet valve is received within the inlet. Preferably, outlet 2 is configured for connection to: a successive biogas volume-measuring system; a gas composition analyser; a biogas collector; a gas container; or a ventilation system. Preferably the biogas collector is a gas sampling bag. The outlet may be connected to valve 5 controlled splitter 3 having first and second tubes 4, 6. The outlet may be connected to a gas stripping unit. Preferably the biogas volume-measuring system is an Automated Methane Potential Test System II (AMPTS).

Description

Gas Analysis Device

Field of the Invention

The invention is in the area of environmental chemistry and biotechnology and in particularly relates to gas analysis, including volume and composition analysis. More particularly, the invention relates to the analysis of biogas, and a device for use with biogas volume-measuring devices to enable capture or redirection of biogas.

Background to the Invention

The biological methane potential test is routinely used to experimentally determine quantities of methane produced per gram of volatile solids (Lesteur et al. 2010) in a simple batch system under anaerobic conditions (Chynoweth et al. 1993). It has been used for designing, monitoring and operating full-scale anaerobic digestion (Lesteur et al. 2010).

In most assays the tests are conducted on the scale of 0.5 L volumes or even smaller (Angelidaki et al. 2009; Raposo et al. 2011). To achieve sufficient reproducibility and standardization the biomass and solid substrate particles used in batch tests are generally homogenized, shifting particle size distribution towards particles smaller than 5 mm (Frigon et al. 2012; Raposo et al. 2011). Methane production from substrates has been shown to increase after the reduction of particle size (Lindmark et al. 2012). In order to attain profitability through the compromise between energy/effort input in substrate modifications and subsequent energy yields (Raposo et al. 2011) the biogas plant decision makers require data derived from site specific inoculum and substrates under conditions mirroring those in full scale reactors (Angelidaki et al. 2009). However, the systematic errors of methane potential test were recently reviewed and the lack of uniformity and multifactorial dependence limiting their direct industrial applicability illustrated (Angelidaki et al. 2009; Walker et al. 2009; Raposo et al. 2011).

In order to solve this problem, the commercially available Automatic Methane Potential Test System II (AMPTS II; Bioprocess Control Sweden AB) (US20120064565A1; Badshah et al. 2012) was upscaled from 0.5 to 5 L (optionally 10 L) for studying the use of real-time inocula from full scale digesters and real-scale substrates available on-site (KolbI et al. 2014). In the AMPTS II, the gas flow measuring device cells are located under the water level of the container; once a sufficient amount of gas (10 mL) passes into the container, the cell cover lifts and shuts again, giving a signal about the volume of gas being processed. It was shown that the same equipment can be used in batch or semi-continuous mode in experiments using real-scale substrates and inocula.

The use of the same equipment and realistic inocula and substrates alleviated many of the previous drawbacks in the measurement approaches giving rise to substantially more realistic methane yields that mirror those observed in real scale industrial size biogas reactors. However, the AMPTS II involves a measurement of methane volume, which is then followed by switching the settings in order to measure total biogas volume, in a separate biogas sample from the same source, in order to determine the volumetric ratio (percentage) of methane in the biogas. The procedure requires tedious manual switching of the measurement devices, requires more laboratory consumables, and is prone to uncertainty (e. g. overestimation of methane yields) since different biogas samples from the same source are used.

For maximal accuracy, a procedure is needed that includes simultaneous measurements of total biogas concentration and the concentrations of individual components in the same gas sample. Current gas concentration determination solutions are for the most part technically complex; W02008003627 describes an apparatus for determining gas mixture component concentrations which includes an ultrasonic flow meter; the procedure involves measuring sound velocity of the gas mixture along with the temperature.

W0201 1110443 describes an apparatus for determination of amounts of greenhouse gases emitted by biogas plants within a given time period. The apparatus employs flow meters coupled to pipes and connected to computation units in a technically complex manner and operates at concentrations at least two orders of magnitude lower than routinely used in industry where methane and carbon dioxide concentrations in biogas regularly fluctuate between 20-60%. In addition, the present invention uses the ratio of the numerous readings through time of the two volumes, (i.e. methane relative to total biogas) to determine the kinetics of change in the biogas composition.

JP2011081989A describes an apparatus for measuring gas flow in which a heater, installed in between a biogas generator and a gas meter, heats the biogas, thus preventing unwanted condensation.

Finally, US8231706B2 describes a method and device for separating methane and CO2 from biogas, which involves counter-current extraction with aqueous amine solution in a packed absorption column and regeneration of the solution by heating under pressure.

The solutions described in the prior art may be technically complex for on-site use in industrial laboratories designed for fast monitoring of biogas production from unknown samples and sufficient high through-put on a larger number of samples in order to deliver sufficient accuracy for determination of hydrolysis constants of organic matter.

A simple solution adopting the available technology is needed which offers a technically straightforward and accurate determination of the biological methane potential in addition to determination of changes in volumetric methane content of the biogas. This is of importance not only when reactors are operated in batch mode, but also semi-continuously. Other alternative procedures include the commercially available OxiTop® bottles (WTWGmbH, Germany) which are, however, expensive, limited to batch mode operation only, and not suitable for large-scale (e. g. multiple 10-liter containers) determination of biogas concentration.

Summary of the Invention

The present invention provides a device for use with a biogas volume-measuring system having a biogas outlet valve arranged to open and thereby release biogas into a liquid reservoir, the device comprising a housing, defining a chamber and having an inlet and an outlet; the housing being submergible in the liquid reservoir; the inlet being configured to receive the biogas outlet valve such that when the biogas outlet valve is open gas is released into the chamber; and the outlet being arranged above the inlet when the biogas outlet valve is received within the inlet.

The device allows the gas released from the biogas volume-measuring system to be captured and channeled, for example allowing the gas to be collected in a biogas collector, or channeled for further analysis. The device enables gas to be sequentially analyzed by a series of gas volume measuring units. Thus, a single stream of gas may be sequentially analyzed to determine the concentration of multiple gas components. In particular, a single stream of gas may be analyzed to determine the total concentration of gas, and the concentration of a particular component such as methane within that biogas.

The outlet of the device of the invention may be configured for connection to any suitable device or downstream application. For example, the outlet may be connected to, or configured for connection to a successive or subsequent biogas volume-measuring system. The outlet may be connected to, or configured to be connected to, a gas stripping unit. In some cases, the outlet may be configured for connection to, or connected to, a gas collector. The gas collector may be gas collection bag, such as a TedlarTM gas sampling bag, or a gas collecting tube. In some cases, the outlet is configured for connection to, or connected to, a venting system for removing collected gas. In some cases, the outlet is configured for connection to, or connected to, a gas storage tank.

The inlet is configured to receive the biogas outlet valve, and additionally may be configured to secure the device in position, such that movement of gas into the chamber, and/or movement in the liquid in the reservoir does not substantially alter the position of the device relative to the biogas outlet valve. The device may be weighted to secure the device in position, for example with a load applied proximal to the outlet. Suitable load materials are well known in the aft The load may, for example, comprise stainless steel.

The dimensions of the load may be configured to cover substantially all of the area of the liquid reservoir, or may only cover some of the area. In some cases, the load takes the form of one or more bars. The load may be positioned over the device in such a way as to spread the load evenly across the suiface of the device, for example in the form of a mesh. The device may be secured in position by means of one or more clamps. The clamps may secure the device to the peripheral wall of the reservoir, or to the biogas outlet valve itself.

In some cases, the outlet of the device is connected to a splitter. The splitter allows the device to be connected to a plurality of downstream devices or applications. In some cases, the splitter is a two-way splitter, connecting the outlet to two outlet tubes. In some cases, the splitter is controlled by a valve. The splitter may have a first tube and a second tube and be controlled by a valve.

The outlet may be configured for connection to, or connected to, a gas container. The gas container may contain an inert gas for purging the device.

The outlet may be configured for connection to, or connected to, a ventilation system.

The ventilation system may be a safety ventilation system. The ventilation system may remove flammable and/or dangerous and/or otherwise undesirable gases from the ambient environment in which the device is used. The ventilation system may be an existing laboratory ventilation system.

In some cases, the device is configured for use with an Automated Methane Potential Test System II (AMPTS II, Bioprocess Control, Sweden). In some cases, the reservoir contains an inert liquid that does not absorb components of the gases that pass through it.

The present invention also provides an apparatus comprising a plurality of devices according to the invention. In some cases, the apparatus comprises 15 devices according to the invention. The invention also provides a kit comprising one or more devices according to the invention, or the apparatus according to the invention, and a biogas volume-measuring device, such as an AMPTS II.

The invention involves a procedure for determination of volumetric percentage of individual components, such as methane, in a single sample of biogas produced in an anaerobic biomass digestion reactor. The device of the invention, designed to capture gas samples, is placed into a gas concentration measuring unit (an AMPTS II unit), recaptures the gas sample, and transfers itto an additional AMPTS II unit. In the first AMPTS II unit, total gas concentration is determined; the gas is transferred through the device to a gas stripping unit (NaOH solution), where CO2 is removed and methane concentration is determined in the second AMPTS II unit. The device is placed over the flow cells of the AMPTS II unit in a liquid-filled bath (the liquid is such that gases that pass through it are not dissolved in it). The gas is directed through the outflow to a two-way splitter controlled by a valve, a system used for flushing the tubing with N2 prior to measurements in order to remove contaminant gases. Gas outlets may be connected to TedlarTM gas sampling bags or a gas concentration measuring device, or they may be connected to ventilation systems in order to safely remove methane containing gases from the working environment. The device is suitable for source containers of volumes of up to 10 L.

Description

The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

The invention, the device, has been developed for capturing biogas after it has been analyzed with the Automatic Methane Potential Test System II (AMPTS II). The captured gas may be passed on to a second AMPTS II unit where only a desired fraction of it(e. g.

methane) is analyzed. The adoption of the device (i) enables determination of methane fraction relative to total biogas through the use of two interconnected AMPTS II units; (ii) simplifies determination of gas composition in industrial settings by adopting TedlarTM bags and industrial type gas meters; (iii) eliminates the need for expensive gas chromatography analyses of biogases and their constituents; (iv) expands the number of gases (C02, CH4, NH3 and H2S) that can be routinely analyzed, depending on the number of sensors integrated in industrial gas meters on site; (v) circumvents the direct release of gases containing flammable methane and odours into laboratory atmosphere by directing them to ventilation shafts; and (vi) enables direct control of readings between different channels of measuring devices.

The device according to the invention may be used with any suitable gas analysis device such as a biomethane potential testing device that has a gas volume-measuring device.

The device is suitable for use with a gas volume-measuring device that utilizes a biogas outlet valve in a liquid reservoir or bath for sensing the volume of biogas produced. In such devices the biogas outflow valve is situated below the liquid reservoir. Gas bubbles flowing into the valve collect until the valve is overfull, at which time the valve opens to release the gas into the liquid reservoir. Opening of the valve is thus indicative of the volume and/or rate of biogas production. As used herein the term biogas outlet valve is used interchangeably with the term biogas outlet sensor.

The device according to the invention comprises a housing that is submergible in the liquid reservoir. It is not necessary for the housing to be entirely submerged within the reservoir, although it may be. However, the housing is submerged such that the interface between the housing of the device and the reservoir of the biogas volume-measuring device is bathed in liquid. In this way, biogas released from the biogas outlet valve flows towards the outlet of the device and does not escape the device through the inlet.

As used herein, the term biogas typically refers to a mixture of gases produced by the breakdown of organic matter in the absence of oxygen. The device of the invention is preferably used in processes involving the analysis of biogas, but may also be used in processes involving the analysis of any gas mixture. Typically, biogas is produced by anaerobic digestion with anaerobic bacteria, or fermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material and crops.

Biogas may contain methane (OH4) and carbon dioxide (002). It may additionally contain hydrogen sulphide (H2S), water, and siloxanes.

In some embodiments disclosed herein a gas-stripping unit is utilized. Gas-stripping units remove one or more components from the gas mixture. In some cases, the gas-stripping unit removes 002 from the gas passed therethrough, resulting in a gas mixture substantially free from 002. The resulting gas mixture may therefore comprise exclusively, or consist substantially of, methane (OH4). The 002 gas-stripper may be NaOH.

This invention relates to a procedure that allows for determination of volumetric percentage of individual components, such as methane, in a single sample of biogas, using an apparatus that sequentially connects two gas concentration measuring devices (AMPTS II units). The invention eliminates the need for separate measurements by redirecting the gas flow from the source (e. g. a digestion reactor) to the AMPTS II unit through an additional AMPTS II unit via the device. In the first AMPTS II unit, total biogas concentration (as mililiter per gram of volatile solids) is determined, and the individual biogas component (e. g. methane) purified and passed to the second AMPTS II unit via the device where its concentration is measured.

In one embodiment of the invention (Figure 3), the biogas sample from a reactor (containing various substrates for anaerobic digestion), containing mostly 002, methane, and water vapor, is passed to the first AMPTS II unit where its concentration is determined. The gas is then captured by the device and transferred to the second AMPTS II unit for determination of methane concentration. The device is placed over the flow cells of the first AMPTS II unit in a liquid-filled bath. The liquid is such that gases that pass through it are not dissolved and therefore not lost but recaptured. The gas is directed from the source to the first AMPTS II unit and through the device out to a two-way splitter controlled by a valve (Figure 1). The first tube from the splitter leads to the second AMPTS II unit whereas the second tube is closed. Exiting the device, the gas sample is passed through a 002 stripping unit -a NaOH solution, fixing 002 and passing purified methane to the second AMPTS II unit. In this unit, volume of methane is determined. The percentage of methane in the biogas is calculated from the data on total biogas and methane obtained from the two AMPTS II units.

In another embodiment of the invention, the first tube from the splitter is closed and the second tube is connected to a gas container for flushing the tubing with N2 prior to measurements in order to remove contaminant gases.

In another embodiment of the invention, only one AMPTS II unit is used (Figure 2); the first tube from the splitter is closed and the second tube is connected to a TedlarTM gas sampling bag (Adtech Polymer Engineering Ltd., Great Britain). "Mien the bag is filled with sufficient amount of biogas, the silicone tubing is sealed with clamps and the bag connected to a gas analyzer (Dräger / Dragwerk AG & Co. KGaA, Germany) for biogas composition determination, and the second bag is put in place. Thus, in addition to the information on the total gas volume determined in the AMPTS II unit, information on gas composition, determined through the use of industrial gas meters, is obtained.

In another embodiment of the invention, one AMPTS II unit is used (Figure 2), receiving a gas sample that had been passed through a gas stripping unit and is therefore purified (e.

g. methane only). As above, a TedlarTM bag is used for collecting the gas sample. Thus, composition of the exiting gas, devoid of carbon dioxide (presumably methane) is determined through the use of industrial gas meter in addition to the total methane volume produced from a single AMPIS II unit. The intention of this embodiment is to enable verification of the composition of the presumably completely scrubbed methane.

In another embodiment of the invention, the first tube of the device is closed and the second tube may be connected directly to an industrial gas analyzer for online gas composition measurements. The intention of this embodiment is to especially allow the use of industrial gas meters for determination of the composition of gas exiting semi-continuous pilot scale reactors.

In another embodiment of the invention (Figure 4), the device as such is used solely for recapturing of released methane containing gases for storage or in order to increase safety in the working environment through venting off the released methane containing gases safely towards safety ventilation instalments. Thus biogas produced is not released directly to ambiental air of the laboratory. This solution also alleviates the release of unwanted odours (and odours (e.g. volatile fatty acids, hydrogen sulfide, ammonia, other) in the laboratory.

The device may consist of multiple hollow sections, each connected to airtight gas lines made of silicone tubing. In order to prevent floating or overturning, the device must be securely fixed in position, by either weighing with a rostfrei load, or clamping to the bottom of the AMPTS II unit with custom made plastic clips, depending on the type of the apparatus. In the AMPTS II unit, the gas bubble travels vertically upwards and is trapped in the device hollow space. The trapped gas can be collected through gas tubing in TedlarTM gas sampling bags of variable volumes for analysis of gas composition using either gas chromatography or readily available gas meters of different types. The invention is presented as a 15-channel device, but the number of channels may be custom tailored as desired.

Use of the device reduces the extent of work otherwise needed to obtain the same amount of data, and decreases the variability in experimental data, as only one set of experiments is performed yielding the two datasets: total biogas evolution (volume and dynamics) and methane evolution (volume and dynamics). The collected data enables determination of changes in methane fraction of the produced biogas following different experimental setups and / or different sample analyses. The invention eliminates the need for manual switching of measuring apparatus components and since a single biogas sample is analyzed, it improves accuracy of the measurement. This leads to an increase in quality control over the estimates of the produced methane yield, as total biogas volume is also determined from the same batch. Determination of contaminant traces of other gases in the methane fraction is possible through adjustment of the number of sensors installed in the industrial gas meter. The approach also eliminates the need for inclusion of complex technology (e. g. gas chromatography) since gas concentrations may be adequately measured with simple and readily available industrial gas meters.

Furthermore, the device may be used to map the effects of various operating temperatures, flow-through rates or variations in ambient pressure. It may also be used as a way to evaluate the measurement accuracy of AMPTS II units and to increase safety at work as it is used to recapture and vent the released methane containing gases safely towards safety ventilation installments that are thus not released directly to ambient air of the laboratory. Finally, the invention is suitable for a range of scales, from 0.5-L containers to 10-L containers, batch and semi-continuous operation, laboratory or pilot scale, i. e., suitable for use in an industrial environment, for which the procedure allows for rapid on-site decisions based on obtained results.

Aspects and embodiments of the present invention will now be illustrated, by way of example, with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

Throughout this specification, including the claims which follow, unless the context requires otherwise, the word "comprise," and variations such as "comprises" and "comprising," will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value.

Similarly, when values are expressed as approximations, by the use of the antecedent "about," it will be understood that the particular value forms another embodiment.

Brief Description of the Figures

Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which like reference numbers indicate the same or similar elements, and in which: Figure 1 is a schematic representation of the device (single channel version) with attached gas line (silicone tubing). The device 1 is a hollow plastic cover and as such may be placed over a gas source so that a gas sample is recaptured and passed through the outlet 2. The outlet 2 is connected to a two-way splitter 3. The first tube 4 from the splitter is connected to a valve 5 whereas the second tube 6 is connected to subsequent AMPTS II units.

Figure 2 is a schematic representation of the installation of the device 1 into a system comprising of an anaerobic digestor or fermentor 8 wherein biomass 7 is being processed and biogas is produced. Biogas is passed through a gas stripping unit 9 to an AMPTS II unit 10 filled with liquid 11 and equipped with a single gas flow sensor 12. The gas is released into the liquid 11 and recaptured within the device 1. The gas is transferred through the outlet 2 and the tube 4 (see Figure 1) to a TedlarTM gas sampling bag 13 which, once full, is transferred to a gas concentration measuring apparatus. Depending on the intention, a gas stripping unit 9 may (for methane analysis) or may not (for total biogas analysis) be installed in-between the reactorS and the AMPTS II unit 10.

Figure 3 is a schematic representation of the main embodiment of the invention, which is the installation of the device 1 in an AMPTS II unit 10 (see Figure 2) where the biogas sample is transferred through the outlet 2 and the second tube 6 to a gas stripping unit 9 and then purified methane is transferred to the second AMPTS II unit 14, equipped with gas flow sensor 15 and filled with liquid 16. A gas stripping unit 9 may optionally be installed in-between the reactor 8 and the first AMPIS II unit 10. Likewise, another device 1 may be installed over the second AMPTS II unit 14 for the purpose of recapturing the purified methane in a sampling bag 13 for analysis, or for safety precautions (ventilation vent for decreasing ambient methane concentration; see Figure 4).

Figure 4 is a schematic representation of the installation of the device 1 into a system wherein biogas is passed through a gas stripping unit 9 to an AMPTS II unit 10 (as in Figure 2). The gas is recaptured within the device 1. The gas is transferred through the outlet 2 and the tube 4(see Figure 1)to a ventilation shaft 17. The gas containing methane is thus removed from the working environment, increasing safety as well as alleviating unwanted odours in said environment.

Figure 5 is a demonstration of determination of biogas composition using two interconnected AMPTS II units. The biogas from the reactors was led to the first AMPTS II unit where it was captured by the device that transferred it to second AMPIS II unit for determination of methane volume.

Figure 6 demonstrates the correlation of Channel 1 of the AM P15 II unit 1 and Channel 1 of the AMPTS unit 2 interconnected through the device in which nitrogen gas was analyzed.

Figure 7 demonstrates a method of securing the device into position above the biogas outlet valve. Load 18 is applied above the device to push the device downwards into the liquid reservoir. Load 18 may be applied above a supporting structure 19 to distribute the load evenly across the device. Load 18 may take the form of a stainless steel rod or bar.

Examples

Example I

Separate determination of cumulative biogas and methane production, i. e. the methane fraction in the biogas, using two connected AMPTS II units The AMPTS II setup was prepared as described in KolbI et. al. (2014). Fifteen anaerobic 5-L reactors were directly connected to the first AMPTS II unit where the cumulative biogas production was measured. The gas bubbles were then collected in the device that was placed over the flow cells of the first AMPTS II unit, and passed to the CO2 stripping units, and from there to the second AMPTS II unit where methane concentration was measured. The device was used on the second AMPTS II unit as well in order to capture produced methane into the TedlarTM bags and analyze its composition with the gas meter (Drager, Germany). Before the start-up of AMPTS II, reactors and devices were flushed with N2 for about 3 minutes to provide anaerobic conditions. Flushing with N2 also increased gas pressure in the device, enabling transport of biogas from the device to the CO2 striping bottles and to the second AMPTS II unit. Glucose was used as substrate in the reactor, organic loading of reactors was lOg volatile solids/L, temperature of anaerobic digestion was 38 ± 2 °C, and the inoculum was obtained from the 4 MWVuOja vas biogas plant (Vuëja vas, Slovenia). Results show a simultaneously determined datasets for methane and total biogas production over time (Figure 5).

Example 2

Verification of AMPTS II channel accuracy between different unit batches of production Two AMPTS II units were used. Synthetic gas in the form of nitrogen gas was passed through the first AMPTS II unit in order to measure the flow rate for 24 h. After that, the device was connected to the AMFTS II unit; gas flow rate was again measured for 24h.

The second AMPTS II unit was then connected to the device outflow lines and gas flow rate was again measured for 24 h. The exchange of lines exiting the device outflow lines enabled the collection of data for the exact correlation of measurement accuracy of AMPTS II units and their channels. The results show that the insertion of the device has no effect on the measured gas flow rate (Figure 6).

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Badshah M, Lam DM, Liu J, Mattiasson B. 2012. Use of an Automatic Methane Potential Test System for evaluating the biomethane potential of sugarcane bagasse after different treatments. Bioresource Technology 114: 262-269.

Bioprocess Control Sweden AB. 2011. AM PTS II Automatic Methane Potential Test System. Operation and Maintenance Manual. Bioprocess Control Sweden AB, Scheelevägen 22, SE-223 63 Lund, Sweden.

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Claims (14)

1. Claims: 1. A device for use with a biogas volume-measuring system having a biogas outlet valve arranged to open and thereby release biogas into a liquid reservoir, the device comprising: a housing defining a chamber and having an inlet and an outlet; the housing being submergible in the liquid reservoir; the inlet being configured to receive the biogas outlet valve such that when the biogas outlet valve is open gas is released into the chamber; and the outlet being arranged above the inlet when the biogas outlet valve is received within the inlet.
2. 2. The device according to claim 1 wherein the outlet is configured for connection to a successive biogas volume-measuring system.
3. 3. The device according to claim 1 wherein the outlet is configured for connection to gas composition analyser.
4. 4. The device according to claim 1 wherein the outlet is configured for connection to a biogas collector.
5. 5. The device according to claim 4 wherein the biogas collector is a TedlarTM gas sampling bag.
6. 6. The device according to any one of the preceding claims wherein the outlet is configured for connection to a gas container.
7. 7. The device according to any one of the preceding claims wherein the outlet is configured for connection to a ventilation system.
8. 8. The device according to any one of the preceding claims wherein the outlet is connected to a splitter having a first tube and a second tube, and being controlled by a valve.
9. 9. The device according to any one of the preceding claims wherein the outlet is connected to a gas stripping unit.
10. 10. The device according to any one of the preceding claims wherein the biogas volume-measuring system is an Automated Methane Potential Test System II.
11. 11. The device according to any one of the preceding claims wherein the liquid reservoir is filled with an inert liquid.
12. 12. An apparatus comprising a plurality of devices according to anyone of the preceding claims.
13. 13. A kit comprising a device or apparatus according to any one of the preceding claims and a biogas volume-measuring system.
14. 14. A device substantially as described herein, with reference to the accompanying drawings.