DE102012005527A1 - Biogas plant comprises first- and second container chamber, a separator for separating biomass solid phase from biomass liquid phase, and a conveyor for conveying biomass liquid phase from first container chamber to second container chamber - Google Patents

Abstract

Biogas plant comprises a first container chamber (10), a second container chamber, a separator (24) for separating biomass solid phase from biomass liquid phase from the first container chamber, and a conveyor for conveying the biomass liquid phase from the first container chamber to the second container chamber. Independent claims are also included for: (1) separator comprising a backwashing device (96) for back washing the separated biomass liquid phase; and (2) producing biogas, comprising performing acetogenesis, and transferring biomass liquid phase during performing methanogenesis.

Description

Background of the invention

The invention relates to a biogas plant having a first tank space and a second tank space.

In known plants for the production of biogas from biomass biomass is placed in a fermentation tank, the so-called main reactor or main fermenter. There conditions are created, which ultimately lead to the formation of biogas in a fermentative degradation or fermentation by means of appropriate bacteria or microorganisms. The biogas thus formed contains methane or methane gas. The burning of methane releases energy, which is used primarily to generate electricity. Therefore, a high proportion of methane is a crucial factor for achieving a high efficiency of production of biogas from biomass.

Biogas raw materials or substrates, in particular plants or plant parts are used as biomass, such as renewable raw materials, in the form of maize silage, grass silage, sugar beets and cereals, which are largely grown as energy crops for biogas production. Furthermore, plant residues serve as biomass, which can not be recycled except for biogas production in the rule. In addition, biomass includes, in particular, fermentable organic waste, such as sewage sludge, biowaste or leftovers, and organic fertilizers, such as manure and manure. Straw and wood are due to the high proportion of fiber materials, especially cellulose (straw) and lignocellulose (wood) poorly degradable in previous methods and thus poorly recyclable.

The fermentative degradation of the biomass by corresponding microorganisms is conventionally divided into four steps, as described in the document DE 10 2008 007 423 A1 In hydrolysis, acidogenesis, acetogenesis and methanogenesis. During the hydrolysis, polymeric macromolecules from the biomass, especially carbohydrates, fats and proteins are hydrolyzed, that is split. The splitting is carried out by microorganisms that excrete different types of exoenzymes or extracellular enzymes, such as amylases, proteases and lipases. These exoenzymes break down at least some of the polymeric macromolecules into fragments and soluble polymers, oligomers and monomers, such as oligosaccharides and monosaccharides (poly- and monosaccharides), peptides, amino acids, long-chain fatty acids and glycerol. In the subsequent second step, the acidogenesis or acidification phase, the products of the hydrolysis, by microorganisms, which are mostly identical to the hydrolyzing bacteria, metabolized. In addition to acetic acid, hydrogen and carbon dioxide in particular short-chain, so-called lower fatty and other carboxylic acids such as valeric, butyric and propionic and short-chain alcohols, such as ethanol. These lower fatty and carboxylic acids and the short-chain alcohols are also converted into acetic acid or acetate and carbon dioxide and hydrogen during the third step, the so-called acetogenesis or the acetogenic step by acetogenic microorganisms. From the acetic acid formed and from the carbon dioxide and hydrogen formed, methane is formed in the fourth step, the methanogenesis or the methane-forming step by means of methanogenic or methanogenic bacteria. These methanogenic bacteria are also called anaerobes because they are only active in the absence of air and are viable. Therefore, the methanogenesis must imperatively exclude air, that is anaerobic.

The four steps mentioned in conventional biogas plants run simultaneously in a fermentation tank. Alternatively, two-step processes are known in which the steps of hydrolysis and acidogenesis are spatially separated from the steps of acetogenesis and methanogenesis. The two spatially separate process stages are considered to be the hydrolysis stage and the methanation stage. Such a two-step process is also in DE 10 2008 007 423 A1 described. However, in the local process, no appreciable increase in terms of the total yield of methane from a particular amount of substrate is achieved compared to conventional biogas processes.

Another disadvantage of known biogas processes is that, after the production of biogas, residual or more viscous fermentation residues remain as residues. These digestate must be stored in relatively large storage containers until they can be applied as fertilizer, especially on agricultural fields.

Not only the storage containers, but also the containers of the main fermenter in conventional biogas plants are comparatively large and require a lot of construction work and constructed area.

Underlying task

The invention has for its object to provide a biogas plant for producing biogas from biomass, in which a high proportion of methane in biogas from the biomass used is obtained at the same time low digestate.

Inventive solution

This object is achieved according to the invention with a biogas plant having a first tank space and a second tank space, in which a separating device for separating biomass solid phase from biomass liquid phase from the first tank space and a conveyor for conveying only the biomass liquid phase from the first tank space are provided in the second container space.

With the inventive separation of solid phase from the biomass of the first container space and the exclusive transfer of biomass liquid phase in the second container space is achieved that the component present in the biomass of cellulose and lignin (especially lignocellulose) is deposited and it prevents these components, in particular the subsequent fourth step, the methanogenesis or the methane-forming step by means of methanogenic or methanogenic bacteria is subjected. As a result, according to the invention, the methane-forming bacteria are not inhibited in their activity by these solid components of the biomass, which is otherwise the case, as has been impressively confirmed by experiments according to the invention. The methane-forming bacteria can therefore implement the separated, purely liquid phase of biomass according to the invention particularly quickly and particularly completely. Furthermore, results in such a reaction in the raw gas produced a particularly high proportion of methane gas.

In the procedure according to the invention, it is particularly advantageous to carry out the separation into solid and liquid phase after the third step, the acetogenesis or acetic forming phase in which the biomass is converted into acetic acid or acetate as well as carbon dioxide and hydrogen by acetogenic microorganisms. This third step is also preferably carried out according to the invention in the first container space.

The invention is therefore generally also directed to separation of solid phase biomass from liquid phase biomass after a step of acetogenesis wherein only liquid phase biomass is transferred to a subsequent step of methanogenesis. Accordingly, in a method according to the invention for producing biogas after a step of acetogenesis, only liquid phase biomass is transferred to a subsequent step of methanogenesis.

The solution according to the invention also avoids the disadvantage of more or less viscous or viscous digestate. In the method according to the invention, instead of particularly low-viscosity and with very little biomass offset fermentation residues. A formation of solid floating ceilings in a fermentation tank, as it is known from existing biogas plants, is reliably prevented by the procedure according to the invention.

With the solution according to the invention, precisely those constituents are separated from the biomass in an early process step, which could in any case not be reacted with the subsequent methanation. These solid components burden the further process in existing biogas plants only and lead to problems that can be avoided according to the invention in a very simple and process-reliable manner.

The separating device provided according to the invention is preferably provided with a sieve for retaining biomass of solid phase from biomass of liquid phase. The screen represents a cost-effective, easily adaptable and at the same time robust way of separating solid and liquid. Advantageously, removal of the liquid phase can be provided on one side of the screen, while removal of the solid phase takes place on the other side of the screen. In this case, the solid phase can first be discharged as still viscous substance and subsequently thickened, wherein the thereby discharged further liquid phase is also subjected to the subsequent methanation.

For purifying such a sieve according to the invention, a backwashing device is preferably provided for backwashing biomass of liquid phase back through the sieve. In this way, the sieve can be cleaned continuously or at intervals of deposits of solid phase and kept continuous for the liquid phase. Already separated liquid phase is deliberately backwashed through the openings provided in the sieve in order to remove solid phase deposited there. With the backwashing, moreover, fermentable constituents are also washed out and rinsed off on the solids of the biomass, so that these constituents can subsequently be fermented and methanized with the liquid phase. In addition, with a swirl bars arranged on the sieve and a continuous movement of the biomass on the sieve over these swirl bars, a suction can be generated on the sieve, with which a settling of solid phase at the openings of the sieve is largely prevented.

The separating device and in particular the screen are arranged particularly advantageously in the first container space itself. For the arrangement of the screen with its ancillary equipment then no separate plant space is required and it can be the biomass involved just at existing biogas plants are also processed in the usual manner. The arrangement of this kind can therefore also be retrofitted very advantageously in existing biogas plants.

A particularly advantageous form of the separating device and in particular of the sieve results if these are designed as a filter basket inserted into the first container space. With the strainer a foreclosure is created in the first container space, in which the liquid phase is tapped, while the remaining still mixed with solid phase biomass is retained outside the screen basket. Outside the screen basket, the biomass can advantageously be circulated with a solid phase, whereby advantageously also the above-mentioned swirl bars are used.

The separating device and in particular the sieve are preferably arranged centrally in the first container space and a stirring device is provided for stirring the biomass in the first container space outside the separating device and in particular the sieve. With the stirring device, the solid phase added biomass can also be conveyed away via a discharge, wherein at this discharge particularly solid phase can settle, which can then be conveyed away and optionally thickened.

In a biogas plant according to the invention, the separating device and in particular the sieve are furthermore advantageously arranged outside the first container space. Such an arrangement may be designed as a separate unit or device that can be retrofitted as a separate unit or integrated into new biogas plants. The device of this kind can also be used in addition to the above-mentioned separating devices, in particular for re-thickening of the viscous phase separated from a first container space.

The separation device of this type is designed overall advantageous with a screw conveyor. The auger can be designed raising the promotional mass, which in particular biomass solid phase can be lifted out of biomass liquid phase. In such upward promotion of the solid phase, the biomass is continuously circulated at the same time, which has an advantageous effect on the achieved separation result.

The screw conveyor is particularly preferably designed with a rotatable screen sleeve surrounding a screw flight. The screw helix serves in this embodiment for the actual conveying of the biomass solid phase, while biomass liquid phase can flow out through the sieve sleeve surrounding the screw helix. The thereby rotatable sieve sleeve makes it possible that it is repeatedly flowed through by the gravitational influence flowing downwards biomass liquid phase in another place. The risk of clogging with solid phase biomass is considerably lower in the case of such a sieve sleeve than in the case of a stationary or stationary sieve sleeve. The spiral screw can be designed to be rotatable or standing in the separation device of this type. A vertical arrangement is of course particularly advantageous in view of the drive technology required for the separating device.

The inventively preferred rotatable screen sleeve is also advantageously cleaned by means of a roller brush, which is located on the outer circumference of the screen sleeve and this there overstretched on its lateral surface in the circumferential direction and optionally also in the axial direction. When gluing, in particular, bristles of the roller brush also pass through the openings formed on the sieve sleeve and thus remove any deposits there may be.

Finally, in the biogas plant according to the invention, the sieve sleeve is also advantageously designed with a multiplicity of openings which can be reduced in size by displacing a second sieve sleeve in its through-flow area. The second sieve sleeve is particularly preferably changeable in its longitudinal direction or axial direction relative to the first-mentioned sieve sleeve in its bearings. With the change in position, there is an offset in the overlap of the openings of both screen sleeves and thus to a change in the size of the flow-through at both screen sleeves for liquid substrate or biomass liquid phase Durchtrittslfäche. The sieve sleeves thus their hole size is changed, whereby it is possible to selectively separate solid components of a predetermined size from the biomass to be separated. This adjustability of the achieved separation result is particularly important if different compositions of the lined substrate are to be found on a biogas plant. Differences in the composition of the substrate arise in particular when z. B. the proportions of maize silage, grass and manure supplied are varied.

According to the invention, a separating device for separating solid phase biomass from biomass liquid phase is accordingly also provided, in which a backwashing device is provided for backwashing separated biomass of liquid phase into the separating device. The invention further provides a process for separating solid phase biomass from liquid phase biomass, wherein separated liquid phase biomass is recycled to the step of separating the solid phase biomass to recover the biomass Additionally, biomass of the liquid phase should be rinsed out of the solid phase biomass.

Brief description of the drawings

An exemplary embodiment of the solution according to the invention will be explained in more detail below with reference to the attached schematic drawings. It shows:

1 a longitudinal section of a first embodiment of a separating device according to the invention in addition to the first container space of an associated biogas plant,

2 the top view II in 1 .

3 the detail III in 2 .

4 the section IV in 2 .

5 the detail V in 1 .

6 a longitudinal section of a second embodiment of a separating device according to the invention,

7 the cross section VII-VII in 6 .

8th a rinsing pipe of the separator according to 6 and 7 .

9 the section IX-IX in 8th .

10 a longitudinal section of a third embodiment of a separating device according to the invention,

11 the cross section XI-XI in 10 .

12 a rinsing pipe of the separator according to 10 and 11 such as

13 the section XIII-XIII in 12 ,

Detailed description of the embodiments

In the 1 and 2 is a first container space 10 a not further illustrated biogas plant for producing methane from biomass shown. The container room 10 is from a circular, pot-shaped container wall 12 surrounded, at the top of a filling opening 14 for biomass is located.

In the container room 10 are a first radially outer agitator 16 and diametrically opposite a second radially outer agitator 18 , The stirrers 16 and 18 are each designed with a vertical axis of rotation, at which at two axially spaced planes radially directed impeller 20 located and by a drive 22 can be set in rotation.

According to the 1 to 5 is in the container room 10 a first embodiment of a separator 24 used to separate the liquid phase in the container space 10 Biomass of their solid phase is used.

The term "liquid phase" is understood to mean all those constituents of the viscous to doughy biomass which are flowable and have a particle diameter of 0.5 to 2.5 mm, preferably 1.0 to 2.0 mm, particularly preferably 1.5 mm do not exceed. Particles larger than said size are counted to the solid phase of the biomass and from the separator 24 retained.

The separator 24 points to a likewise cup-shaped sieve basket 26 on the of a cylindrical sieve 28 is formed. In the sieve 28 There are a lot of openings 30 , Which are designed so small that they can pass through only particles of the liquid phase. The passage takes place from radially outside to radially inside. It is located inside the screen basket 26 and thus in the center of the container wall 12 a central agitator 32 with a drive 34 structurally similar to the agitators 16 and 18 is constructed. The central agitator 32 serves to circulate the inside of the sieve 28 collecting liquid phase of biomass.

On the outside of the screen 28 or the outer lateral surface of the screen basket 26 are located from this obliquely outwardly projecting, substantially vertical swirl bars 36 , from whose protruding part associated openings 30 in the sieve 28 are at least partially covered. Together with the of the agitators 16 and 18 generated flow of biomass in the radially outer annular space of the container space 10 produce these swirl bars 36 at the openings 30 a suction effect, by means of residues and blockages from the sieve 28 be sucked away radially outward. In this way, the openings 30 on the sieve 28 kept clean and free for the passage of liquid phase.

At the bottom area under the central agitator 32 is in the strainer basket 26 an outlet 38 for biomass liquid phase, with a radially outwardly guided discharge line 40 is formed. Through the outlet pipe 40 is the liquid phase by means of a pump 42 from the center of the container space 10 inside the strainer basket 26 aspirated.

Radially outside of the sieve 28 is located at the bottom of the container space 10 a discharge 44 For Biomass solid phase. The exhaustion 44 is with a discharge funnel 46 formed, which collects on the ground and at the same time by the agitators 16 and 18 in a circle around the sieve 28 collected solid material down to collect and to a screw conveyor 48 leads. The screw conveyor 48 runs obliquely upwards with a spiral helix 50 that by a drive 52 is rotated while in a housing 54 Biomass solid phase up from the tank space 10 out promoting. At the upper end of the case 54 there is an exit 56 for biomass liquid phase, by adding a sieve 58 is arranged over which the obliquely upward conveyed mass is pushed. The biomass liquid phase, which is in the housing 54 located and also with the screw conveyor 48 was promoted, passes through this sieve 58 down into a return line 60 one from which they return to the container room 10 running. About the exit 56 for biomass of liquid phase is an outlet 62 for biomass solid phase, which in this way separately from the container space 10 is dissipated. Separating and carrying out the biomass of solid phase from the container space 10 In particular, this is done so that this component of the biomass does not burden a subsequent process of methanation of the biomass. It has been found that in particular the biomass described here as a solid phase can not be converted into methane in a biogas plant or can only be converted into methane with great effort and process outlay. It makes more sense to eliminate this component of the biomass from the substrate to be methanized and to subject only the remaining liquid phase of biomass to methanation. It can then significantly shorter process times with higher yield and higher quality of biogas (especially higher methane gas content) can be achieved, which represents the overall more effective and efficient way of producing methane gas in a biogas plant.

In the 6 to 9 is a second example of a separator 64 for separating biomass into liquid phase and solid phase in a process of producing biogas, especially methane. The separator 64 is outside the container space 10 established. You will be through an inlet 66 Biomass from the tank room 10 containing both solid and liquid phase substrate. The substrate or material passes into a screw conveyor 68 that with a hollow cylindrical helix 70 is designed, which of a cylindrical sieve sleeve 72 is surrounded. In the sieve sleeve 72 is a variety of openings 74 formed, each having an opening width of 1.0 mm to 2.0 mm, preferably 1.5 mm. The sieve sleeve 72 is on two bearing rollers 76 mounted on its outer periphery obliquely upwards rotatably mounted and thereby by a drive 78 in rotation or circulation offset. By turning the sieve sleeve 72 becomes the substrate located therein from the container space 10 along the helix 70 promoted diagonally above. During this promotion, the substrate is also circulated. At the same time, the material of liquid phase passes through the openings 74 down through the sieve sleeve 72 out, while the solid phase material is conveyed up over the top of the screen sleeve, only to separate therefrom the liquid phase biomass from the screen sleeve 72 to be discharged.

The sieve sleeve 72 is by means of the bearing rollers 76 on a swivel base 80 stored, whose inclination relative to a pedestal 82 is adjustable and fixable at an angle between 10 ° and 40 °, preferably between 20 ° and 30 °.

For cleaning the openings 74 on the sieve sleeve 72 is located on the outer lateral surface, in particular diametrically opposite the pivot base 80 an axially directed roller brush 84 , Alternatively, the roller brush advantageously based on 7 laterally on the left or right top of the sieve sleeve 72 be arranged. With the roller brush 84 be the openings 74 Overpainted and residues on them are cleaned and into the interior of the sieve 72 pushed back.

For removing the biomass liquid phase at the separator 64 is under the sieve sleeve 72 a discharge 88 for biomass liquid phase provided with a discharge funnel 90 is designed. The discharge funnel 90 collects the material over the entire lower projection surface of the sieve sleeve 72 and leads it into a discharge line 92 in which there is a pump 94 sucks.

To the sieve sleeve 72 their openings 74 especially continuous, is a backwashing 96 provided by means of a at the discharge line 92 connected backwash line 98 Material of liquid phase into the interior of the sieve sleeve 72 is returned. In this case, the recirculated material enters an axially inside the screen sleeve 72 extending rinse tube 100 , preferably at its top a longitudinal row of openings 102 having. In the rinsing pipe 100 Furthermore, alternatively or additionally, water may be supplied under pressure, in particular fresh water or else wastewater or residual water which has remained as residue in the methanation and only contains a very small proportion of biomass.

The rinsing pipe 100 is in accordance with the 8th and 9 clamshell shaped with axially displaceable shells, whereby the openings 102 are adjustable in their opening width. Through the openings 102 The recycled material is liquid phase from the inside against the sieve sleeve 72 in the direction of their openings 74 sprayed so that contaminants and residues steadily out of the openings 74 be washed out.

Such recycling of biomass liquid phase and / or water also contributes significantly to the fact that in the sieve 72 and their spiral helix 70 Biomass as such is washed or washed out. In this case, additional material of liquid phase is washed out of the solid phase material of this biomass, which would have been discharged without such backwashing with the solid phase. The additionally washed-out material of liquid phase also passes through the openings 74 from the sieve sleeve.

In the 10 to 13 is a third embodiment of a separator 104 shown as also from the container space 10 separate device with a spiral screw 70 together with sieve sleeve 72 is working. Inside the sieve sleeve 72 this separator 104 there is a rinsing pipe 100 , which as a percolate tube on the underside with a series of openings 102 is designed. The openings 102 lead on a in the longitudinal direction of the Ausspülrohres 100 extending, located below this baffle plate 104 , The baffle plate 104 causes through the openings 102 recycled material of liquid phase in the sieve sleeve 72 is sprayed over a larger area and in this way contributes to a particularly extensive washing out or rinsing of biomass liquid phase from the solid phase biomass.

Finally, it should be noted that all the features that are mentioned in the application documents and in particular in the dependent claims, in spite of the formal reference back to one or more specific claims, even individually or in any combination should receive independent protection.

LIST OF REFERENCE NUMBERS

10

first tank room of a biogas plant

12

cup-shaped container wall

14

Filling opening for biomass

16

first outer agitator

18

second outer agitator

20

Agitator blades of the agitators

22

Drive of the agitators

24

first embodiment of a separating device ( 1 to 6 )

26

strainer

28

Strainer of strainer basket

30

Opening in the sieve

32

central agitator in the strainer basket

34

Drive of the central agitator

36

swirl bar

38

Outlet for biomass of liquid phase

40

Outlet line of the outlet

42

Pump the outlet

44

Discharge for biomass of solid phase

46

Leakage funnel of the discharge

48

Auger conveyance of the discharge

50

screw spiral

52

Drive the worm helix

54

Housing of the helix

56

Outlet for biomass of liquid phase

58

Sieve at the exit

60

Return line at the exit

62

Outlet for solid phase biomass

64

second embodiment of a separating device ( 6 to 9 )

66

Inlet for biomass from the first tank room

68

auger

70

screw spiral

72

perforated sleeve

74

Opening in the sieve sleeve

76

Bearing roller for the sieve sleeve

78

Drive for the sieve sleeve

80

swivel base

82

stand base

84

Slant adjustment on the swivel base

84

rolling brush

86

Outlet for solid phase biomass

88

Leaching for biomass of liquid phase

90

Leakage funnel of the discharge

92

Discharge line of the discharge

94

Pump of exhaustion

96

Backwashing device for biomass of liquid phase

98

Backwashing line of the backwashing device

100

Rinsing pipe of the backwashing device ( 8th and 9 two shells)

102

Opening in the rinsing pipe

104

third embodiment of a separating device ( 10 to 13 )

106

baffle plate

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008007423 A1 [0004, 0005]

Claims (11)

Biogas plant with a first container space ( 10 ) and a second container space, in which a separating device ( 24 ; 64 ; 104 ) for separating biomass of solid phase from biomass of liquid phase from the first container space ( 10 ) and a conveyor for conveying only the biomass liquid phase from the first container space ( 10 ) are provided in the second container space. Biogas plant according to claim 1, in which the separating device ( 24 ; 64 ; 104 ) with a sieve ( 28 ; 72 ) for retaining solid phase biomass from liquid phase biomass. Biogas plant according to claim 2, wherein a backwashing device ( 96 ) for backwashing biomass of liquid phase back through the screen ( 72 ) is provided. Biogas plant according to one of Claims 1 to 3, in which the separating device ( 24 ) and in particular the sieve ( 28 ) in the first container space ( 10 ) are arranged themselves. Biogas plant according to claim 4, in which the separating device ( 24 ) and in particular the sieve ( 28 ) than in the first container space ( 10 ) inserted screen basket ( 26 ) are designed. Biogas plant according to claim 4 or 5, wherein the separating device ( 24 ) and in particular the sieve ( 28 ) in the middle in the first container space ( 10 ) and a stirring device ( 16 . 18 ) for stirring the biomass in the first container space ( 10 ) outside the separator ( 24 ) and in particular the sieve ( 28 ) is provided around. Biogas plant according to one of Claims 1 to 3, in which the separating device ( 64 ; 104 ) and in particular the sieve ( 72 ) outside the first container space ( 10 ) are arranged. Biogas plant according to Claim 7, in which the separating device ( 64 ; 104 ) with a screw conveyor ( 68 ) is designed. Biogas plant according to claim 8, in which the screw conveyor ( 68 ) with a helical coil ( 70 ) surrounding, rotatable sieve sleeve ( 72 ) is designed. Separating device ( 64 ; 104 ) for separating biomass of solid phase from biomass of liquid phase, in which a backwashing device ( 96 ) for backwashing separated biomass liquid phase in the separator ( 64 . 104 ) is provided. Process for the production of biogas, in which after a step of the acetogenesis only biomass liquid phase is transferred to a subsequent step of methanogenesis.

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