NL2005004C2

NL2005004C2 - Biogas system.

Info

Publication number: NL2005004C2
Application number: NL2005004A
Authority: NL
Inventors: Mirik Castro; Samuel Castro
Original assignee: Simgas B V
Priority date: 2010-06-30
Filing date: 2010-06-30
Publication date: 2012-01-03
Also published as: AP2013006688A0; CN103003410A; CN103003410B; AP3498A; WO2012002813A1

Description

NLP186904A

Biogas system BACKGROUND

The invention relates to a biogas system. Biogas systems comprise a digestion chamber to contain a mixture of 5 manure and other biodegradables, called feedstock, that is partly resolved in water in order to produce methane gas. The methane gas can be used for household or small industrial purposes.

A known biogas system is build of bricks. As a 10 closed dome of bricks is necessary to enclose the methane gas, a skilled mason has to be present at the building site and even a skilled mason has some weeks work to build one biogas system, and before building heavy bricks need to be supplied to the building site. A brick biogas system needs 15 to be engineered for every size and every location separately. Once it is in place it size is fixed.

It is an object of the invention to provide a biogas system that can be provided in an efficient manner.

It is an object of the invention to provide a biogas 20 system that can be assembled by low skilled people.

It is an object of the invention to provide a biogas system that can be easily scaled up.

2

SUMMARY OF THE INVENTION

The invention provides a biogas system comprising an elongated tank forming an elongated internal digester 5 chamber, wherein the tank comprises a top tank half and a bottom tank half having horizontally extending flanges that are coupled against each other, wherein the top tank half comprises in series a front top segment, multiple intermediate top segments and a back top segment having 10 vertically extending flanges that are coupled against each other, wherein the bottom tank half comprises in series a front bottom segment, multiple intermediate bottom segments and a back bottom segment having horizontally extending flanges that are coupled against each other.

15 The biogas system according to the invention can be supplied as separated sections which are subsequently assembled by bringing the horizontal and vertical flanges of the different against each other. This can be done by low skilled people.

20 In an embodiment the intermediate top segments are identically formed.

In an embodiment the intermediate bottom segments are identically formed.

In an embodiment the intermediate top segments and 25 the intermediate bottom segments are identically formed.

In above mentioned preferred embodiments the tank can be scaled up in its length by supplying the number of identically formed intermediate segments that are neccessary. The identically formed segments can be produced 30 in an efficient manner.

For the same efficiency reasons the front bottom segment and the back bottom segment can be identically formed.

In an embodiment the biogas system comprises an 35 expansion chamber above the top tank half that is separated from the digestion chamber except for an outlet channel between the expansion chamber and the digestion chamber. The 3 expansion chamber can store a fraction of the mixture that is expelled from the digestion chamber via the outlet channel due to the production of methane gas. The mass of the expelled fraction can keep the produced methane gas 5 under some pressure.

In an embodiment thereof the upper tank half comprises an upper wall that bounds the upper side of the digestion chamber, wherein the outlet channel extends downwards from the upper wall into the digestion chamber. 10 The lower side of the outlet channel thereby determines the maximum height of the methane gas body in the digester chamber. In this manner it is prevented that too much mixture is expelled towards the expansion chamber.

In an embodiment thereof the outlet channel is 15 formed in the front top segment, whereby only one outlet channel is provided.

In an embodiment the upper tank half comprises an upper wall that bounds the upper side of the digestion chamber, and an inlet channel that extends downwards from 20 the upper wall into the digestion chamber. The inlet chamber allows the methane gas to be enclosed inside the digestion chamber while more feedstock can still be inserted in the digestion chamber.

In an embodiment the inlet channel extends in 25 downward direction deeper into the digestion chamber than the outlet channel.

In an embodiment the inlet channel is formed in the back top segment, whereby only one outlet channel is provided.

30 In an embodiment the segments comprise a continuous insertion chamber along the flanges, wherein the insertion chambers of the coupled flanges are positioned straight opposite each other, wherein a common resilient sealing is inserted in the opposite insertion chambers. The 35 inserted and enclosed resilient sealing seals the coupled flanges along the length, whereby the mixture and the produced methane gas remains enclosed inside the digestion 4 chamber, at least to a large extent.

In an embodiment thereof the segments comprise a wall section between the flanges, and a U-shaped insertion profile for the sealing between the wall section and its 5 flange, wherein the wall section connects to the back of the U-shaped insertion profile and the flange forms a continuation of one of the legs of the U-shaped insertion profile. The U-shaped insertion profile forms a clearly visual indication for the intended position of the seal, 10 whereby can be ensured that the seal will be placed in the intended way.

In an embodiment thereof the resilient sealing comprises an elongated base strip having sealing flaps along the length of the base strip that extend sideways from the 15 base strip.

In particular, the base strip and the sealing flaps are in cross section configured as arrow heads that point outside. The arrow heads indicate the intended insertion direction of the seal.

20 In an embodiment the flanges are coupled by multiple couplings that are evenly distributed along the flanges, wherein the couplings comprise a coupling pin having a coupling head and a coupling shaft extending from the coupling head, wherein the flanges comprise sets of 25 aligned holes wherein the coupling shaft is inserted.

In an embodiment thereof one of the flanges is provided with an annular protrusion that is inserted in a hole in its opposite flange to form a male-female connection. The male-female connection already ensures the 30 alignment of the flanges before the coupling pins are inserted to obtain a permanent coupling.

In an embodiment thereof one of the flanges is provided with a first locking edge inside the hole, wherein the coupling shaft is provided with a series of second 35 locking edges for one way locking interaction with the first locking edge.

Alternatively, the couplings are provided with an 5 additional ring plate or cup spring with a first locking edge inside its centre hole, wherein the coupling shaft is provided with a series of second locking edges for one way locking interaction with the first locking edge.

5 In an embodiment the tank is symmetrical at least regarding its outer shape with respect to a longitudinal vertical plane of symmetry that extends through the middle of the front segments, the intermediate segments and the back segments, wherein along the vertically extending 10 flanges the holes change into a protrusion or reverse when passing the longitudinal vertical plane of symmetry, and along the horizontally extending flanges the holes and protrusions are opposite to each other when considered at the opposite sides of the longitudinal vertical plane of 15 symmetry.

In an embodiment the segments comprise wall sections that are made of HDPE having nitrogen bubbles enclosed. The wall sections thereby provide substantial thermal isolation of the digestion chamber, whereby the 20 methane forming process is not disturbed by changes in the ambient temperature.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular 25 the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications .

30 BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which: 35 Figure 1 is an isometric view of a modular biogas tank according to the invention;

Figure 2 is an isometric view of the biogas tank 6 according to figure 1, wherein the upper parts have been removed;

Figure 3 is an isometric view of the biogas tank according to figure 2, wherein some side parts have been 5 removed;

Figure 4 and 5 are side views of the biogas tank according to figure 1, for different illustrating purposes;

Figure 6 is a back view of the biogas tank according to figure 1; 10 Figures 7A and 7B are a cross section and an isometric view of a coupling of the biogas tank at the position as indicated in figure 2;

Figure 8 is a cross section of an alternative coupling for the biogas tank at the position as indicated in 15 figure 2;

Figure 9A is a cross section of two wall segments and a seal at the position as indicated in figure 3;

Figure 9B is an isometric view of the seal according to figure 9A; and 20 Figure 10 is a cross section of the wall of the biogas tank at the position as indicated in figure 2.

DETAILED DESCRIPTION OF THE INVENTION 25

Figures 1, 4 and 6 show a modular biogas tank 1 according to an embodiment of the invention. The elongated biogas tank 1 is destined to digest a mixture of manure and biodegradables, called feedstock, that is partly dissolved 30 in water in order to produce methane gas under low pressure.

De biogas tank 1 comprises a front bottom segment 20, three intermediate bottom segments 40, 41, 42 and a back bottom segment 30, a front top segment 50, three intermediate top sections 70, 71, 72 and a back top segment 35 60 that are coupled along their sides to bound a closed digestion chamber 2. The biogas tank 1 further comprises two vertical side walls 80, 82, a vertical front wall 81, and a 7 vertical back wall 83 on the top segments 50, 70, 71, 72, 60 to bound an open expansion chamber 3 having an overflow 84 above the digestion chamber 2. The back top segment 60 is provided with an inlet channel 5 that has been extended by a 5 vertical shaft 90 aside the expansion chamber 3. The front top segment 50 is provided with an inlet channel 4 that communicates between the digestion chamber 2 and the expansion chamber 3. The segments are discussed in more detail hereafter, wherein reference is made to a horizontal 10 plane of symmetry U, a longitudinal vertical plane of symmetry V and a lateral vertical plane of symmetry W of the outside shape of the biogas tank 1.

The front bottom segment 20, the back bottom segment 30, the front top segment 50 and the back top 15 segment 60 have an identical outside shape, which is described hereafter under reference to the front top segment 50.

The front top segment 50 comprises a top wall section 59 extending parallel to the horizontal plane of 20 symmetry U, an elongated straight front wall section 51 and two straight side wall sections 53 that together form a boxshaped stiffening construction, a second, substantially square straight front wall section 52 standing outwards from the middle of the elongated front wall section 52, two 25 convex front wall sections 54 that extend between the square front wall section 52 and the elongated front wall section 51, and two convex side wall sections 55 below the straight side wall sections 53.

The front top segment 50 further comprises a first 30 flange 56 that extends along the straight front wall section 51 and the convex wall sections 54, 55 in the horizontal plane of symmetry U, a second flange 57 that extends along the convex side walls 55 and the straight side walls 53 and a third flange 58 that extends along the straight top wall 35 59, both parallel to the lateral vertical plane of symmetry W.

The intermediate bottom segments 40, 41, 42 and 8 the intermediate top segments 80, 81, 82 have an identical shape, which is described while referring to the second top segment 81 in figure 3.

The second top segment 81 comprises a straight, 5 rectangular top wall 73 and two substantially square straight side walls 74 standing outwards from the top wall 73. The second top segment 80 further comprises first flanges 75 that extend along the lower side of the side walls 74 in the horizontal plane of symmetry U, second 10 flanges 76 that extend along the sides of the side walls 74 and third flanges 77 that extend along the sides of the top wall 73, both parallel to the lateral vertical plane of symmetry W. Along the short corner sides of the top wall 73, the top segment 81 comprises upright insertion profiles 78 15 wherein the vertical side walls 80, 82 have been inserted.

Figure 9A shows in detail the second flange 57 of the front bottom segment 20 and the second flange 76 of the first intermediate bottom part 40, which are kept against each other by means of identical couplings 100 of which one 20 is shown in more detail in figure 7A. The couplings 100 are equally distributed along all flanges to keep the flanges and thereby the segments tightly against each other over their entire length.

As shown in figure 9A, the front bottom segment 20 25 and the first intermediate bottom segment 40 are both provided with a U-shaped profile 11 that at the outer side of the biogas tank 1 connects the respective wall section 53, 74 to the respective flange 57, 76, and at the inner side of the biogas tank 1 is connected to an end flange 12. 30 The U-shaped profile 11 bounds an elongated, continuous insert chamber 10 along the flanges, wherein a resilient, elongated seal 14 has been inserted. The seal 14 is shown in detail before its insertion in figure 9B. The seal 14 comprises a flexible base strip 15 having for each insert 35 chamber 10 two slim side flaps 16, 17 and a hollow side flap 18 on both sides of the base strip 15. The base strip 15 and the side flaps 16, 17, 18 are (co)extruded from rubber, and 9 form arrow heads that point in the direction of the bottom of the insert chamber 10.

As far as now described, the shape of each of the segments is symmetrical with regard to the planes of 5 symmetry U, W, V.

The coupling 100 comprises a circular hole 101 in the second flange 57 of the front bottom segment 20 and an annular protrusion 102 on the second flange 76 of the first intermediate bottom segment 40 that is confined in the 10 circular hole 101 like a male-female connection to bring and keep the flanges 57, 76 aligned against each other in a fool proof manner. Inside the protrusion 102 there is a smaller hole 103 which is provided with a locking edge 104. The coupling 100 further comprises a plastic locking pin 110 15 which is shown in detail in figure 7B. The locking pin 110 comprises an elongated shaft 112 and a broader, circular flat head 111. The shaft 112 comprises a beveled front 113, two notches 114 on either side followed by an elongated hole 115 that divides the shaft 112 into two resilient halves 116 20 having multiple locking edges 117 at the outer side. The locking edges 104, 117 are designed such that the locking pin 110 immediately locks permanently after having been inserted into the smaller hole 103 in direction F, which lock can only be tightened further by pulling or pushing 25 further in direction F.

Figure 8 shows an alternative coupling 200. The alternative coupling 200 comprises the same circular hole 101 in the second flange 57 of the front bottom segment 20 and the annular protrusion 102 on the second flange 7 6 of 30 the first intermediate bottom segment 40 that is confined in the circular hole 101 like a male-female connection to bring and keep the flanges 57, 76 aligned against each other in a fool proof manner. Inside the protrusion 102 there is a smaller hole 203. The coupling 200 further comprises a 35 plastic locking pin 210 having an elongated shaft 212 and a broader, circular flat head 211. The shaft 212 comprises a beveled front 213, two notches 214 on either side followed 10 by an elongated hole 215 that divides the shaft 212 into two resilient halves 216 having multiple locking edges 217 at the outer side. The alternative coupling further comprises a ring plate or cup spring 220 having a hole 218 which is 5 provided with a locking edge 204. The locking edges 204, 217 are designed such that the locking pin 210 immediately locks permanently after having been inserted into the smaller hole 103 in direction F, which lock can only be tightened further by pulling or pushing further in direction F, such as by 10 means of the pulling side of a hammer head 300 that is supported on the cup spring 217 to bias the cup spring 217.

Per segment the protrusions 102 and holes 103 are distributed such along the flanges that on the vertically extending flanges the holes 103 change into an protrusion 15 102 or reverse when passing the longitudinal vertical plane of symmetry V, and that for the horizontally extending flanges the holes 103 and protrusions 102 are opposite to each other when considered at the opposite sides of the longitudinal vertical plane of symmetry V. In this manner 20 the intermediate segments 40, 41, 42, 70, 71, 72 all still are identically shaped, enabling one and the same intermediate segment to be flipped over in direction A or turned around its vertical axis in direction B as indicated in figure 3 to be used at any intermediate position of the 2 5 biogas tank 1. On the same manner the front bottom segment 2 0 and the back bottom segment 30 are still identically shaped to be interchangeable by turning around its vertical axis in direction C as indicated in figure 3.

The front top segment 50 uniquely further 30 comprises an rectangular outlet shaft 65 extending downwardly from the top wall 59 to bound the outlet 4. The outlet shaft 65 has a lower outlet edge 66 that extends parallel to and above the first flange 56. The back top segment 60 uniquely comprises a rectangular inlet shaft 67 35 to bound the inlet 5. The inlet shaft 67 has a lower inlet edge 68 that extends parallel to and above the first flange 56. In vertical direction, the lower outlet edge 68 extends 11 below the lower inlet edge 66, over about 10 centimeter. The inlet edge 68 has a smaller cross section than the outlet edge 66 to prevent that pieces of the feedstock are thrown into the digestion chamber 2 cannot be taken out at the 5 outlet 4 anymore. Both the front top segment 50 and the back top segment 60 are provided with upright insertion profiles 91, 95 wherein the vertical front wall 81 and the vertical back wall 83 have been inserted.

The segments have been manufactured by injection 10 moulding of nitrogengas enclosing HDPE. A cross section of a wall section is shown in figure 10. The wall section encloses nitrogen bubbles in its centre and smaller nitrogen bubbles at both sides of the centre. The solid outside faces of the wall section are free of bubbles. The enclosed 15 bubbles provide thermal insulation of the digester chamber 2.

The methane forming process inside the digester chamber 2 is explained under reference to figure 5. The digester chamber 2 is fully filled by insertion of a mixture 20 of water and feedstock via the inlet shaft 67, at a maximum level E some centimeters from the dome that is formed by the upper wall sections 59, 73. The mixture starts to generate methane gas, which escapes from the mixture and stays enclosed in the digestion chamber 2 to push down the level 25 of the mixture. The lowest level D is determined by the height of the lower edge 66 of the outlet shaft 65, as the gas will escape via the outlet when the level has reached the lower edge 66. During lowering the level, the surplus of mixture is pushed into the expansion chamber 3 via the 30 outlet 5. The mass of the expelled mixture keeps the enclosed methane gas under pressure, which pressure is enough to force the methane gas into a hose 400 that is connected to the top side of the digester chamber 2. The overflow 84 ensures that when the expansion chamber reaches 35 its maximum level, the mixture is expelled in a controlled manner.

At the lowest level D the mixture in the digester 12 chamber 2 occupies 75% of the total volume of the digester chamber 2. That is, the total volume of the stored methane gas can be 25% of the total volume of the digester chamber 2. The maximum volume of the expansion chamber 3 is 25% of 5 the volume of the digester chamber 2 as well. The entire biogas tank 1 can be scaled up or down only by adding or removing some identical intermediate segments 40, 70. In this manner the above mentioned volume rates will remain the same. The intermediate segments, and the front segments and 10 the back segments can be stacked and nested in themselves, allowing the biogas tank 1 to be transported as a compact package to its place where it will be assembled and employed.

It is to be understood that the above description 15 is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present 20 invention.

Claims

A biogas system comprising an elongated tank forming an elongated internal digestive chamber, the tank comprising a tank upper half and a tank lower half with horizontally extending flanges coupled to each other, the upper tank half in series having a front upper segment, a plurality of intermediate upper segments and a rear upper segment with a plurality of upper segments comprises vertically extending flanges which are coupled against each other, wherein the tank lower half comprises in series a front sub-segment, a plurality of intermediate sub-segments and a rear sub-segment with a plurality of vertically extending flanges which are coupled against each other.

The biogas system according to claim 1, wherein the intermediate upper segments are identically shaped.

The biogas system according to claim 1 or 2, wherein the intermediate sub-segments are identically shaped.

The biogas system according to claims 2 and 3, wherein the intermediate upper segments and the intermediate lower segments are identically shaped.

A biogas system according to any one of the preceding claims, wherein the front sub-segment and the rear sub-segment are identically shaped.

6. Biogas system as claimed in any of the foregoing claims, comprising an expansion chamber above the tank upper half which is separated from the digestion chamber after an outlet channel between the expansion chamber and the digestion chamber.

7. Biogas system according to claim 6, wherein the tank upper half comprises an upper wall which delimits the upper side of the digestive chamber, wherein the outlet channel extends downwards from the upper wall into the digestive chamber.

A biogas system according to claim 6 or 7, wherein the outlet channel is formed in the front upper segment.

9. A biogas system according to any one of the preceding claims, wherein the tank upper half comprises an upper wall bounding the upper side of the digestive chamber, and an inlet channel which extends downwardly from the upper wall into the digestive chamber.

10. Biogas system according to claims 7 and 9, wherein the inlet channel extends deeper into the digestive chamber in downward direction than the outlet channel.

The biogas system according to claim 9 or 10, wherein the inlet channel is formed in the rear upper segment.

12. Biogas system according to any one of the preceding claims, wherein the segments along the flanges comprise a continuous insert chamber, wherein the insert chambers of the coupled flanges are positioned straight opposite each other, wherein a joint, resilient seal is accommodated in the insert chambers arranged opposite each other.

13. Biogas system according to claim 12, wherein the segments between the flanges comprise a wall portion, and between the wall portion and its flange a U-shaped insert profile for the seal, the wall portion being connected to the back of the U-shaped insert profile and the flange forms a continuation of one of the legs of the U-shaped insert profile.

14. Biogas system according to claim 12 or 13, wherein the resilient seal comprises an elongated base strip with sealing flaps protruding laterally from the base strip.

The biogas system according to claim 14, wherein the base strip and the sealing flaps are arranged in cross-section as outward-pointing arrowheads.

A biogas system according to any one of the preceding claims, wherein the flanges are coupled by means of a plurality of couplings evenly distributed over the flanges, the couplings comprising a coupling pin with a coupling head and a coupling shaft extending from the coupling head, the flanges grouping include aligned openings into which the coupling shaft is inserted.

The biogas system according to claim 16, wherein one of the flanges is provided with an annular protrusion that is inserted into an opening in its opposite flange to effect male-female coupling.

A biogas system according to claim 16 or 17, wherein one of the flanges is provided with a first locking edge on the inside of the opening, the coupling shaft being provided with a series of second locking edges for one-way locking action with the first locking edge.

19. Biogas system according to claim 16 or 17, wherein the couplings are provided with an additional ring plate or disc spring with a first locking edge on the inside of its middle opening, the coupling shaft being provided with a series of second locking edges for one-way locking action with the first locking edge.

20. Biogas system according to any of claims 17-19, wherein the tank is symmetrical at least with respect to its outer shape with respect to a longitudinal vertical symmetry plane extending through the center of the front segments, the intermediate segments and the rear segments, wherein along the vertically extending flanges the openings merge into a protrusion or vice versa when passing the longitudinally extending vertical symmetry plane, and viewed along the horizontally extending flanges the openings and protrusions on the opposite sides of the longitudinally extending vertical symmetry plane are opposite to each other.

21. A biogas system according to any one of the preceding claims, wherein the segments comprise wall sections made from HDPE in which nitrogen bubbles are enclosed. o-o-o-o-o-o-o-o