The invention relates to a device for discharging gases. The invention also relates to a method for discharging gases.

At locations where livestock is kept or where manure is stored so-called manure gases are created by the manure produced by the livestock as a result of biochemical processes which take place in the biologically active manure. A large part of the gases can be harmful to people and animals. For instance created by dairy cattle manure or slurry are, among other things, hydrogen sulphide (H2S) and sometimes also hydrogen cyanide/prussic acid (HCN), which can both also occur in highly hazardous concentrations, mostly in stored manure such as slurry or liquid manure. Ammonia (NH3), methane (CH4) and carbon dioxide (C02) are further released, among other things. These latter two are also significant greenhouse gases and also occur in the highest concentrations by far.

At locations where livestock is kept rumen fermentation is another significant source of greenhouse gases such as methane and carbon dioxide. In the paunch, the first rumen of ruminant animals, ingested feed is pre-digested by micro-organisms. The feed which is fermented here and the greenhouse gases created in this process are expelled via the mouth of the ruminant animals. A dairy cow can thus expel for instance more than 500 litres of methane gas per day.

In order to prevent a hazard for humans and animals, livestock accommodations or manure pits where the manure gases may result are ventilated. Because methane, ammonia and hydrogen cyanide are lighter than air, they escape relatively easily. Carbon dioxide and hydrogen sulphide are heavier than air and therefore remain 'suspended' in lower zones. Release of methane and carbon dioxide into the atmosphere has highly undesirable effects on the climate and should therefore be prevented. For this purpose it is often attempted in existing manure systems to limit the release of the gases, for instance by providing a better closure of manure pits. Because new manure is continuously produced throughout the day, and this manure must also be transported to the manure pits, a complete seal is however not feasible. Because of this, the manure gases will continue to be releases into the livestock accommodation and thereby also into the atmosphere. Closing the manure pit is not a suitable solution here either since other dangers also arise due to the increased concentrations, such as a danger of explosion.

Existing livestock accommodation devices do not suffice either for capturing gases, such as greenhouse gases, released by rumen fermentation. As much as 80% of the methane emission can originate from rumen fermentation. Because this is not discharged effectively, it finds its way into the animal accommodation and finally into the atmosphere.

It is now an object of the invention to provide a device for discharging gases, whereby the above stated drawback is reduced or can even be obviated.

This object is achieved according to the invention with a device for discharging gases, which device comprises a gas source such as for instance a manure gas source such as a manure pit, which gas source is connected to an inflow opening of a transport conduit for discharging gases and which transport conduit also comprises an outflow opening, wherein the device also comprises an air pump configured to transport the gases from the gas source, through the transport conduit to the outflow opening, which outflow opening debouches under the ground.

The gases are here according to the invention preferably manure gases and/or rumen fermentation gases, the gases preferably comprising methane gas. The manure gas source is here preferably a manure gas source and/or a feeding location for ruminant animals.

By discharging the manure gases and/or rumen fermentation gases it is possible to prevent free release thereof into the atmosphere and/or to prevent dangerous concentrations from occurring due to accumulation in for instance an animal accommodation.

The device is therefore suitable to be used to prevent free release into the atmosphere of the gases from an environment with an increased concentration of the gases, such as in or close to the gas source. The gases therefore have a different composition than the atmosphere, because it would otherwise not be useful to discharge the gases away from a gas source in order to prevent the gases from being released freely into the atmosphere.

Connecting the gas source to the inflow opening of a transport conduit enables the gases created or present in the gas source to be discharged through the transport conduit. In a manure pit the inflow opening can here for instance be arranged at some height above the manure level. An air pump provides for the displacement of the gases through the transport conduit to the outflow opening. By having the outflow opening debouch under the ground the gases are released in the ground. The soil is hereby enriched with the gases and optionally the oxygen-rich air pumped along together with the gases. This additional supply of gases and air can enrich the ground. By applying the device for the purpose of discharging manure gases released from manure these gases are not released into the atmosphere or for instance the animal accommodation .

Another advantage of the device according to the invention is that the device can also be configured specifically for a gas source with for instance air rich in carbon dioxide or oxygen. The gas source can for instance also be ambient air. Infiltration of carbon dioxide and/or oxygen into the soil can then be achieved with the device. Infiltrating such gases into the soil enables positive stimulation of the soil life.

Another embodiment of a device according to the invention is a device wherein the outflow opening debouches below the ground surface level of a field, preferably debouches at a depth of a maximum of 140 cm below the ground surface level, preferably at a depth of 60-140 cm.

By having the outflow opening debouch under a field, such as a meadow or farmland, the gases infiltrated into the ground, such as the gases such as for instance manure gases and the oxygen contained in the air which may have been pumped along, can be absorbed by the soil life and the crops on the fields. By arranging the debouchment at a depth of a maximum of 140 cm below the ground surface level the gases can diffuse in the ground and reach the root system of the crops in effective manner. The debouchment is preferably provided at a depth of 60 cm - 140 cm below the ground surface level. Any work on the field will hereby not interfere with the transport conduits arranged in the ground.

In another embodiment of a device according to the invention the outflow opening is formed by a plurality of perforations of the transport conduit.

Forming the outflow opening by means of perforations of the transport conduit enables the gases to exit the transport conduit via the perforations. The perforations are then preferably distributed uniformly over the desired outflow zone or distributed for a uniform outflow in the outflow zone on the basis of for instance a pressure drop. When the transport conduit debouches under a field, the desired outflow zone is for instance distributed over the part of the transport conduit which is situated under the field.

In a preferred embodiment of a device according to the invention the transport conduit also comprises an underground drainage pipe, wherein the outflow opening of the transport conduit is also formed by the perforations of the drainage pipe.

Drainage pipes are arranged under many fields or other agricultural land. They can be in active use, but may also be remnants of an obsolete drainage system. Making the underground drainage pipe part of the transport conduit by coupling the pipes enables them to be reused in effective manner or to be used for the purpose of achieving the soil infiltration of the gases.

The drainage pipe preferably also serves here as drainage for water. The drainage pipe can then fulfil a dual function as part of the transport conduit, wherein the manure gas transport and the drainage are combined. The outflow of the drainage pipe for the drained water is here preferably provided with a water seal such as a swan neck or water column, so that sufficient pressure can be applied in the transport conduit for the desired soil infiltration and in order to prevent outflow of gases from occurring through the drain of the drainage pipe.

Another embodiment of a device according to the invention is a device which also comprises an aspirator with an inlet, an outlet and an underpressure inlet, wherein the air pump displaces clean air and is connected to the inlet of the aspirator, the outlet is connected to the inflow opening of the transport conduit and wherein the underpressure inlet is connected to the gas source.

Because the gases may be corrosive due to their constituents and because additional aeration of the ground around the outflow opening may be desirable, it is advantageous to have the air pump displace clean air by for instance placing it outside the gas source. Carrying the clean air from the air outlet of the air pump through the inlet of the aspirator enables the gases to be drawn in via the underpressure inlet. The mixture of clean air and gases can then be transported from the outlet of the aspirator, via the transport conduit to the outflow opening.

Another embodiment of a device according to the invention is a device wherein the gas source comprises at least a feeding location for ruminant animals, wherein the feeding location comprises a feeding trough and the inflow opening is arranged above the feeding trough.

Because a very high proportion of the methane emission at a location where ruminant livestock is kept is produced by rumen fermentation, the device is preferably configured such that an inflow opening is arranged above the feeding trough. The gases created and/or released there can then be discharged in effective manner.

In another embodiment of a device according to the invention the feeding location comprises a collecting cover which is arranged above the feeding trough and under which the inflow opening is arranged.

By arranging a collecting cover above the feeding trough and arranging the inflow opening thereunder, above the feeding trough, the gases which are lighter than the atmosphere, including methane gas, are captured and discharged more efficiently.

In yet another embodiment of a device according to the invention the collecting cover is arranged on a frame, which frame is pivotable relative to the feeding trough between a position of use, in which the collecting cover is situated above the feeding trough, and a filling position in which the collecting cover is situated adjacently of the feeding trough for the purpose of unimpeded filling of the feeding trough.

By making the collecting cover displaceable by arranging it pivotally on a frame the feeding trough can be made easily accessible for filling up or cleaning. By pivoting the collecting cover into the filling position with the frame the feeding trough can be filled from the upper side in simple manner. When the feeding trough has been filled, the collecting cover can pivot back to the position of use, wherein the collecting cover is situated above the feeding trough.

Another embodiment of a device according to the invention is a device wherein the feeding location is provided with a closure extending from the feeding trough to the collecting cover, which closure is preferably flexible.

Arranging a closure between the feeding trough and the collecting cover prevents free air flow in between the feeding trough and the collecting cover. This allows fewer gases to escape. By making the closure flexible, for instance in the form of flexible flaps, the closure can be folded away in simple manner when access to the feeding trough is required. The closure can then for instance be folded away by the livestock.

It is another object of the invention to provide a method for discharging gases such as for instance manure gases, wherein gases from a gas source are transported via a transport conduit to an outflow opening of the transport conduit by means of an air pump and wherein the outflow opening debouches under the ground.

By discharging the gases away from the gas source with an air pump and allowing them to flow out under the ground via an outflow opening of a transport conduit the undesired emission of gases from a gas source can be reduced or even prevented.

Another embodiment of the method according to the invention is a method wherein the outflow opening debouches below the ground surface level of a field, preferably debouches at a depth of a maximum of 140 cm below the ground surface level, preferably at a depth of 60-140 cm. The advantages of this method have already been described in an embodiment of the device according to the invention.

In a preferred embodiment of the method according to the invention the transport conduit also comprises an underground drainage pipe. Existing drainage pipes can hereby be advantageously used for the soil infiltration of the gases.

A device according to the invention is preferably applied for the method.

These and other features of the invention are further elucidated with reference to the accompanying drawings.

Figure 1 shows a schematic overview of a first embodiment of a device according to the invention.

Figure 2 shows a schematic overview of a second embodiment of a device according to the invention.

Figure 3 shows a ground plan of a third embodiment of a device according to the invention.

Figure 4 shows a schematic cross-sectional view of the embodiment of figure 3.

Figure 5 shows a schematic cross-section of a feeding location according to a third embodiment according to the invention.

Figure 6 shows a schematic cross-section of the feeding location according to figure 5 in the filling position.

Figure 1 shows a schematic overview of a first embodiment of a device 1 for discharging manure gases 2. The manure gases 2 are created in a manure gas source 3 by the slurry 4 present in the manure gas source 3. Arranged on manure gas source 3 is a transport conduit 5. The manure gas source is connected to the inflow opening 6 of transport conduit 5. An air pump 7 displaces the manure gases 2 in the direction of the arrow 8 through the transport conduit 5 which debouches under the ground below a field 9. The outflow opening of transport conduit 5 is formed by perforations 10. The transport conduit 5 is arranged at a depth d under the ground surface level 11 of field 9 so that the crop 12 on field 9 can absorb the manure gases which have infiltrated into the ground 13.

Irrespective of the other features, it is the case that the depth d preferably corresponds with the depth at which drainage pipes are arranged for a determined type of ground or crop.

Figure 2 shows a schematic overview of a second embodiment of a device 21 for discharging manure gases 2. The reference numerals of features corresponding with the first embodiment are identical to the reference numerals of figure 1. The air pump 7 is connected to the inlet 28 of the aspirator 29, also referred to as ejector. The underpressure inlet 30 is connected to the manure gas source 3. The outlet 31 of aspirator 29 is connected to the inflow opening 6 of the transport conduit 5. Because the air pump 27 does not come into contact with the manure gases which are carried through transport conduit 5, it need not be suitable for displacing combustible gases. Additional air, such as ambient air, is also blown in via the inlet 28, whereby the ground 13 under field 9 is also aerated.

Figures 3 and 4 show a third embodiment of a device 41 according to the invention. The ground plan of figure 3 shows the drainage pipes 50 which are arranged under the field 49 and which are connected to a collecting drain 51 which debouches into a ditch 54 lying adjacently of field 49. The transport conduit 45 is connected on one side to manure gas source 43 and connects under field 49 to drainage pipes 50.

Figure 4 shows a schematic cross-sectional view through line IV-IV of the embodiment shown in figure 3. The drainage pipes 50 are arranged under the ground surface level 48 of field 49. The openings in drainage pipes 50 form the outflow opening of transport conduit 45. The openings in drainage pipes 50 debouch under the ground 53 of field 49 on which a crop 52 is for instance arranged. The height of the outflow 54 of collecting drain 51 enables a water column to form in the outflow 54 for the purpose of obtaining sufficient counter-pressure in the transport conduit 45 and drainage pipes 50. A good infiltration into the soil 53 can be obtained hereby.

Figure 5 shows a schematic cross-sectional view of a feeding location 61 according to a third embodiment according to the invention. The feeding location 61 is provided with a feeding trough 62 with feed 63. Arranged above feeding trough 62 is a transport conduit 64 provided with inflow openings 65. A collecting cover 66 is arranged on a frame 67 which is pivotable in the direction of arrow 68 from the shown position of use to a filling position. Flexible flaps 69 extend from feeding trough 62 to the collecting cover 66 in order to prevent free air throughflow between feeding trough 62 and collecting cover 66.

Figure 6 shows a schematic cross-section of the feeding location according to figure 5 in the filling position. In the filling position the frame 67 is pivoted in the direction of arrow 68, whereby the collecting cover 66 is no longer situated above feeding trough 62. The flexible flaps 69 and the collecting cover 66 thereby no longer block access to feeding trough 62. Feed can hereby be replenished in simple manner in the filling position. For instance with a vehicle 70 provided with a conveyor belt 71 whereby feed 63 can be inserted into feeding trough 62.