DE102010006080A1 - Plant, useful for processing biomass and producing biogas, comprises mixing- and crushing device for incorporating solid biomass and fermentation liquid, fermentor for promoting fermentation of biomass mash and phase separation device - Google Patents

Abstract

Plant (10) comprises: a mixing- and crushing device (30) for incorporating a mixture of a solid biomass and a fermentation liquid and for mixing and crushing the mixture to a biomass mash; a fermentor (40) connected to the mixing- and crushing device for incorporating the biomass mash, and to promote the fermentation of the biomass mash; and a phase separation device (60) connected to the fermentor to accommodate the fermented biomass mash, which is designed to separate the fermented biomass mash into a liquid phase and a solid phase. Plant (10) comprises: a mixing- and crushing device (30) for incorporating a mixture of a solid biomass and a fermentation liquid and for mixing and crushing the mixture to a biomass mash; a fermentor (40) connected to the mixing- and crushing device for incorporating the biomass mash, and to promote the fermentation of the biomass mash; and a phase separation device (60) connected to the fermentor to accommodate the fermented biomass mash, which is designed to separate the fermented biomass mash into a liquid phase and a solid phase. The phase separation device is connected to the mixing- and crushing device such that the liquid phase in the mixing- and crushing device, is used as fermentation liquid for producing the biomass mash. An independent claim is also included for processing biomass and producing biogas, comprising: mixing the solid biomass and fermentation liquid, crushing the obtained mixture to a biomass mash in the mixing- and crushing device; feeding the biomass mash into the fermentor and subjecting the mash for fermentation; feeding the fermented biomass mash from the fermentor into the phase separation device, which is connected to the fermentor, and separating the fermented biomass mash into the liquid phase and solid phase; and producing the biomass mash by using the liquid phase as the fermentation liquid in the mixing- and crushing device.

Description

Field of the invention

The invention relates to a system and a method for the energetic utilization of renewable resources. In particular, the invention relates to a biogas plant, in which preferably biomass is processed biochemically and used for biogas production, and a method for operating such a biogas plant.

Background of the invention

Biomass refers to constituents of organic material that are present in a defined ecosystem that has been biochemically synthesized. Such biomass, in which in particular biochemically stored solar energy is bound, can also be used as a self-renewing energy supplier, i. H. be referred to as a so-called "renewable energy source".

Here are plants as so-called primary producers by photosynthesis in a position to build up from the non-renewable energy sources (CO ₂ , H ₂ O, minerals) while supplying energy with large amounts of biomass, which made available in particular in the form of carbohydrates after the transformation become.

Not only in developing countries, but to an increasing extent also in the industrialized countries, such biomass in the form of wood, vegetable matter and manure have become an important source of energy.

The plants for the utilization of biomass are called bioreactor or biogas plant. They have at least one container, the so-called fermenter, in which certain microorganisms are cultured under optimal conditions in a nutrient medium, either to win the cells themselves, parts of them or one of their metabolites, especially the so-called biogas, and as an energy source to be used industrially or in households to a great extent.

The aforementioned, mostly multi-stage bioreactors are designed for continuous operation and work continuously over several years. Such biogas generators often have several, standing arranged, usually designed as a cylindrical hollow body fermenter. These fermenters have a capacity of up to several thousand cubic meters.

There are essentially three different methods for introducing biomass into a fermenter of a biogas plant known. First, it is known to introduce the substantially solid biomass via screw or pressing devices directly from a reservoir into the fermenter. In order to ferment it in the fermenter, a fermentation liquid (eg liquid manure) is often pumped into the fermenter. Secondly, it is known to mix the substantially solid biomass in a mixing pump with fermentation liquid and to supply this mixture to the fermenter. Such mixing pumps are marketed, for example, by Vogelsang under the product name "Quickmix", by Börger under the product name "SSR" and by the company Wangen under the product name "Biomix". Third, in a modification of this method, it is known to pre-mix the solid biomass and the fermentation liquid in a pre-pit and to supply this mixture to the fermenter, for example likewise by means of a pump.

It is also known, in the conventional methods described above, to provide further method steps for comminuting the substantially solid biomass before it is introduced into the fermenter in order to accelerate the fermentation process.

In the methods described above for introducing the biomass into the fermenter large fermentation volumes are required, d. H. It is a fermenter with a large capacity required because the resulting liquid in the fermentation or the high water content of introduced manure can not be discharged due to the necessary compliance with the residence time in the fermenter. A large capacity of the fermenter means a larger surface of the fermenter and thus a high energy loss. In other words: the efficiency of the biogas plant is reduced. In conventional processes in which no pre-comminution of the biomass takes place, this disadvantageous effect is intensified by the fact that un-shredded biomass particles cause long residence times in the fermenter due to their low specific surface area. Furthermore, as the capacity of a fermenter increases, the amount of energy needed to agitate the fermenting biomass in the digester increases, which in turn reduces the efficiency of the biogas plant. Finally, the introduction of usually liquid manure into the fermenter, which is required in some known biogas plants, also leads to a reduction in the efficiency of such plants.

The present invention is therefore based on the object of providing an improved (in particular more energy-efficient) plant for the fermentation of biomass and to provide such a process. Overall, the advantages of the known different biomass fermentation plants are maintained without their disadvantages having to be accepted.

Summary of the invention

This object is achieved by a plant for the fermentation of biomass according to claim 1 and a method for the fermentation of biomass according to claim 10.

According to the invention prior to introduction into the fermenter, the substantially solid biomass, z. B. corn plants, processed together with originating from the fermenter fermentation liquor in a mixing and crushing device to a biomass pulp. The mixing and crushing device causes the cells of the biomass components are at least partially broken and leak out cell contents, which leads to a better fermentation of the subsequently introduced into the fermenter biomass pulp.

A phase separation device is connected to the fermenter so that fermented biomass pulp from the fermenter can be fed to the phase separation device and the phase separation device can separate the biomass pulp from the fermentor into a solid phase and a liquid phase. The liquid phase provided by the phase separation device represents the fermentation liquid originating from the fermenter, with which further biomass in the mixing and comminution device can be processed into a biomass pulp, in order to feed it to the fermenter again.

Preferably, in the plant according to the invention for the fermentation of biomass, the substantially solid biomass is first fed into a feed and pre-crushing device. Preferably, the feeding and pre-crushing device is a container having a feed trough and a throat pump in combination with a cutting screen, wherein biomass introduced into the container via the feed trough falls into the throat pump and is conveyed by the throat pump in the direction of the perforated screen and therethrough is pushed through. In this case, a pre-shredding of the biomass and a sorting out of foreign bodies, which have dimensions which are larger than the diameter of the holes of the perforated screen, are advantageously carried out.

Downstream of the perforated screen is the mixing and crushing device, in which the pre-shredded biomass is introduced from the fermenter together with the fermentation liquid provided by the phase separation device. Preferably, in the mixing and crushing device, the mixture of pre-shredded biomass and fermenter liquid originating from the fermenter is mixed by means of at least one rotating cutter disk and further comminuted. In this case, the cutting disc is preferably designed such that the comminution is so strong that the cells of the plant constituents of the biomass are at least partially broken up and cell contents escape. The resulting slurry from biomass and from the fermenter derived fermentation liquid is particularly well suited to be fermented in the fermenter.

It has been shown in test experiments that, depending on the substrate, a knife peripheral speed of between approximately 26 and 35 m / s gives the best results, namely with a diameter of the knife of 60 cm. The residence time in the mixing and comminution device should be between 100 and 200 s, preferably between 120 and 180 s, depending on the fiber length and the solids content of the biomass. In tests, a capacity of the mixing and crushing device of 1500 liters has proved to be advantageous.

The phase separation device for producing fermentation liquid from the fermenter is preferably a compression screw, to which a buffer container is connected for the storage of the fermentation liquid produced by the pressing screw. The presscake (i.e., the solid phase) produced by the phase separator may be stored in a further buffer container for further use or disposed of. Alternatively, the obtained in the phase separation device press cake (solid phase) can be introduced into the fermenter again.

Further advantages of the invention and preferred embodiments will become apparent from the following objective description, the features of the dependent claims and the drawings.

Brief description of the drawings

A preferred embodiment of the invention is illustrated in the accompanying drawings.

1 shows a schematic representation of a preferred embodiment of a biogas plant according to the invention.

2 shows a detailed view of a preferred embodiment of a mixing and crushing device of the biogas plant according to the invention.

Detailed Description of a Preferred Embodiment

The invention will now be explained in more detail with reference to a preferred embodiment.

1 shows a preferred embodiment of a biogas plant according to the invention 10 , The biogas plant 10 includes a feed and pre-crushing device 20 for feeding biomass into the biogas plant 10 , For this purpose, the feed and Vorzerkleinerungsvorrichtung 20 preferably a feed trough 22 up, over a collecting tank to a throat pump 24 leads. By means of the throat pump 24 is the in the feed and Vorzerkleinerungsvorrichtung 20 fed biomass through a perforated screen 26 pressed. Here is the perforated screen 26 preferably configured such that a pre-comminution of the biomass and a sorting out of foreign bodies takes place, having dimensions greater than the diameter of the holes of the perforated screen 26 are.

Downstream of the perforated screen 26 is a mixing and crushing device 30 into which through the perforated sieve 26 pre-shredded biomass is introduced. In addition to the pre-shredded, but substantially solid biomass is in the mixing and crushing device 30 introduced a fermentation liquid. This fermentation liquor is passed through a phase separation apparatus described in more detail below 60 provided by means of the from a fermenter 40 derived fermented biomass pulp, which has liquid and solid components, can be separated into a solid phase and a liquid phase.

Preferably, in the mixing and crushing device 30 the mixture of pre-shredded biomass and by means of the phase separation device 60 produced fermentation liquid from the fermenter 40 mixed by at least one rotating cutter disc and further crushed. In this case, the rotating cutter disk of the mixing and crushing device 30 Preferably configured such that the crushing of (already by the feed and Vorzerkleinerungsvorrichtung 20 pre-shredded) biomass is so strong that the cells of the plant components of the biomass are at least partially broken and leak out cell contents.

2 shows a preferred embodiment of a mixing and crushing device 30 in detail. This preferred embodiment of the mixing and crushing device 30 consists essentially of a mixing container 31 and a stirrer 33 with a motor 34 and a knife disk 32 , The agitator 33 can be by means of a pivoting device 35 between an operating position in which the cutter disc 32 inside the mixing container 31 is arranged, and pivot an end position in which the knife disc 32 outside the mixing container 31 is arranged. Is the agitator located? 33 in the operating position, so can by means of the engine 34 the knife disk 32 be set in rotation, so that in the mixing container 31 located biomass and fermentation liquid due to the rotation of the knife disc 32 be mixed and crushed and a biomass pulp can be produced. The mixing and crushing device 30 also has connections 36 for feeding biomass and fermentation liquid into the mixing container 31 into or for the removal of biomass pulp from the mixing container 31 out.

At the in 2 illustrated preferred embodiment of a mixing and crushing device 30 It has been shown in tests that, depending on the substrate, a knife peripheral speed between about 26 and 35 m / s gives the best results, with a diameter of the knife of about 60 cm. The residence time in the mixing and comminution device should be between 100 and 200 s, preferably between 120 and 180 s, depending on the fiber length (eg when using maize plant as biomass) and the solids content of the biomass. In tests, a capacity of the mixing and crushing device 30 of 1500 liters proved to be advantageous. However, those skilled in the art will recognize that, depending on the batch size requirements, the capacity and other parameters of the mixing and crushing apparatus 30 can be scaled arbitrarily.

The in the mixing and crushing device 30 prepared porridge from biomass and from the fermenter 40 fermentation liquor is then the fermenter 40 supplied (for example by means of a pump). The fermenter 40 has the configuration well known to those skilled in the art for providing suitable fermentation conditions, for example, an agitator and a heater, so that they need not be described in more detail. For example, the fermenter 40 have a capacity of 1800 m ³ and a diameter of 20 m.

For example by means of a pump fermented biomass pulp from the fermenter 40 containing solid and liquid components, the phase separation device 60 be supplied. Optionally, between the fermenter 40 and the phase separator 60 another buffer tank 50 for storing fermented biomass pulp from the fermenter 40 be provided. About this buffer tank 50 If desired, fermented biomass pulp may also be returned to the fermenter 40 be traced back as in the 1 indicated by the dashed arrows.

Preferably, the phase separation device is 60 to a press screw, with which the fermented biomass porridge from the fermenter 40 , which has solid and liquid components, is separated into a liquid phase (fermentation liquid or pressing liquid) and a solid phase (press cake). However, those skilled in the art will recognize that many other devices can be used as the phase separation device in the sense of the present invention. For example, this can be used a tubular sieve with internal screw conveyor. In this case, the fermented biomass pulp is abandoned on one end of the tube screen and circulated by means of the internal screw conveyor and further transported through the tube screen. At the other end of the tubular sieve, the solid phase is dammed up with the help of a bluff body in order to build up a suitable internal pressure in the tubular sieve. The liquid phase is pushed out of it by the increased pressure and by the constant circulation through the tubular sieve.

If necessary, if, for example, further biomass in the feed and Vorzerkleinerungsvorrichtung 20 can be fed from the phase separator 60 provided, from the fermenter 40 fermentation liquor to that of the feed and Vorzerkleinerungsvorrichtung 20 pre-crushed biomass are added so that the resulting mixture of pre-shredded biomass and from the fermenter 40 originating fermentation liquid in the mixing and crushing device 30 be processed into a biomass pulp and then the fermenter 40 can be supplied to the fermentation turn, as has already been described above, so that a kind of cycle is formed, which is essentially from the mixing and crushing device 30 , the fermenter 40 and the phase separator 60 is trained.

Optionally, between the phase separator 60 and the mixing and crushing device 30 another buffer tank 70 for storage of the phase separation device 60 be provided provided fermentation liquid. That of the phase separator 60 produced press cake (ie the solid phase) can in another buffer tank 80 be stored or disposed of for further use. Alternatively, in the phase separation device 60 accumulating press cake (solid phase) in turn into the fermenter 40 be fed as indicated by the dotted arrows in 1 is indicated.

Advantages of the biogas plant according to the invention or of the process according to the invention are: an increased biogas yield per ton of biomass; an improved utilization of the given capacity of a fermenter; the possibility to use smaller fermenters; increased methane yield (13-19%); the dry matter content of the biomass pulp in the fermenter can be adjusted as desired via the proportion of recycled solid phase; the residence time of the biomass pulp is no longer dependent on the hydraulic residence time in the fermenter, but this is now determined by the maximum possible dry matter content in Biomassebrei and thus, based on the fermentation volume, greatly increased; Due to the extremely high degree of comminution in the mixing and crushing device, the biomass pulp becomes very homogeneous and can easily be pumped and stirred (energy saving).

The foregoing objective description of the invention is for explanatory purposes only. The invention is in no way limited to the embodiment described, but may be adapted by a person skilled in a seemingly appropriate manner to individual operating requirements that may differ from the described operating conditions. Further, those skilled in the art will recognize that the terms used herein, such as "forward," "upper," "lower," "outer," and the like, are not intended to indicate the orientation of the In this way, the elements according to the invention which are specified in greater detail are restricted in any way, but merely serve to distinguish these elements from one another.

LIST OF REFERENCE NUMBERS

10

biogas plant

20

Infeed and pre-crushing device

22

feed trough

24

revenge pump

26

strainer

30

Mixing and crushing device

31

mixing tank

32

diameter disc

33

agitator

34

engine

35

Pivot means

36

Supply and discharge connection

40

fermenter

50

Buffer tank for biomass porridge

60

Phase separator

70

Buffer tank for liquid phase

80

Buffer tank for solid phase

Claims (10)

Investment ( 10 ) for processing biomass and for producing biogas, comprising: a mixing and crushing device ( 30 ) for receiving a mixture of substantially solid biomass and a fermentation liquor and for mixing and comminuting this mixture into a biomass pulp; a fermenter ( 40 ), which with the mixing and crushing device ( 30 ) to receive the biomass pulp and configured to promote the fermentation of the biomass pulp; and a phase separation device ( 60 ) with the fermenter ( 40 ) to receive the fermented biomass pulp and configured to separate the fermented biomass pulp into a liquid phase and a solid phase; wherein the phase separation device ( 60 ) so with the mixing and crushing device ( 30 ) that the liquid phase in the mixing and crushing device ( 30 ) is used as fermentation liquid for the production of biomass pulp. Investment ( 10 ) according to claim 1, wherein the plant ( 10 ) a feed and pre-crushing device ( 20 ). Investment ( 10 ) according to claim 2, wherein the feed and pre-crushing device ( 20 ) a feed trough ( 22 ), a throat pump ( 24 ) and a perforated screen ( 26 ). Investment ( 10 ) according to claim 1, wherein the mixing and crushing device ( 30 ) consists of a container with a rotatably mounted blade disc. Investment ( 10 ) according to claim 1, wherein the phase separation device ( 60 ) comprises a press screw. Investment ( 10 ) according to claim 1, wherein between the phase separation device ( 60 ) and the mixing and crushing device ( 30 ) a buffer container ( 70 ) is provided for storage of the liquid phase. Investment ( 10 ) according to claim 1, wherein between the fermenter ( 40 ) and the mixing and crushing device ( 3 ) a buffer container ( 50 ) for storing the fermented biomass pulp from the fermenter ( 40 ) is provided. Investment ( 10 ) according to claim 1, wherein the phase separation device ( 60 ) with a buffer container ( 80 ) is connected to store the solid phase. Investment ( 10 ) according to claim 1, wherein the phase separation device ( 60 ) so via a piping to the fermenter ( 40 ), that of the phase separation device ( 60 ) provided solid phase can be returned to the fermenter. A method of processing biomass and producing biogas, the method comprising the steps of: mixing the substantially solid biomass and a fermentation liquor and comminuting this mixture into a biomass pulp in a mixing and crushing device ( 30 ); Feeding the biomass pulp into a fermenter ( 40 ) to ferment the biomass pulp; the feeding of the fermented biomass pulp from the fermenter ( 40 ) into a phase separation device ( 60 ) with the fermenter ( 40 ), and separating the fermented biomass pulp into a liquid phase and a solid phase; and using the liquid phase in the mixing and crushing device ( 30 ) as fermentation liquid for the production of the biomass pulp.

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