DE102016105937B4 - Injection of liquid organic biomass for solid-state fermentation - Google Patents

Abstract

Process for the production of biogas in a solid-state fermenter in which percolate is applied to the stackable biomass in order to produce biogas in a fermentation process, characterized in that liquid biomass is additionally applied to the stackable biomass.

Description

Technical area

The present invention relates to a method and a device for producing biogas from organic solids, preferably from stackable biomass.

State of the art

It is known to ferment organic solids and in particular stackable biomass in so-called solid fermenters (garage-like fermenter boxes) in order to obtain biogas therefrom.

Subsequently, the biogas is usually used for heat generation and / or combined heat and power plants for the coupled generation of electricity and heat. After purification, the biogas can also be sold as biomethane and can for example be fed into the natural gas grid or used for the operation of vehicles.

In the known solid-state fermentation, the organic solids are introduced into a solid-fermenter and then periodically charged with a percolate stream. The percolate drizzled through the solid bed formed by the stackable biomass is usually collected at the bottom of the solid-fermentor, circulated, and then trickled over the stackable biomass in the respective or another solid-fermentor. The percolate stream is applied to the biomass from the top of the solids fermenter to start the fermentation process and then keep it going.

The Feststofffermenter is usually designed like a garage and has gas-tight walls, ceiling and floor, which are often poured concrete, and a gas-tight gate. In this way, anaerobic digestion of the biomass is possible. The biogas is usually withdrawn via corresponding line devices from the solid fermenters. Through the gate, the solid fermenter can be loaded with the organic solids.

After the fermentation process of loading a solids fermenter with organic solids is completed, ie after about 3-5 weeks, the digestate is discharged through the gate from the corresponding Feststofffermenter.

In the known methods, the organic solids are fermented in an anaerobic environment in the solid fermenter, wherein the correspondingly required microorganisms are supplied inter alia by means of the drizzled percolate. The organic solids are correspondingly "inoculated" by the percolate. In the solid fermenter, the organic solids are then fermented to form biogas.

Accordingly, the conventional fermentation process can be divided into the following four stages: In the first stage, hydrolysis, the biomolecules present in the organic biomass are broken into fragments by reaction with water, releasing hydrogen and CO ₂ . In the second step, acidogenesis, the fragments formed in the hydrolysis are reacted on the one hand into lower fatty acids and / or carboxylic acids such as butyric acid or propionic acid, on the other hand into lower alcohols such as ethanol. In the third stage, acetogenesis, the lower fatty acids and / or carboxylic acids formed during the hydrolysis and acidogenesis and the lower alcohols are converted by acetogenic microorganisms primarily to acetic acid, or to its dissolved salt, the acetate. In the fourth stage, methanogenesis, on the one hand, acetic acid is converted to methane and carbon dioxide by acetic acid-splitting methanogens, and on the other hand methane of hydrogen and CO _{2 is produced} by another group of methanogens. The biogas resulting from this process is largely made up of methane. Accordingly, it is a high-energy gas, which is formed under the anoxic conditions from the organic solids by fermentation.

From the DE 10 2005 029 306 B4 a method for operating a Feststofffermenteranlage and a device for this purpose is known. According to the teaching of this document, the percolate flow for each intended solid fermenter is controlled so that the acid formed in the solid fermenters is flushed out with the percolate stream so that no acidification of the biomass stored in the solid fermenter occurs and at the same time the percolate flow has such a loading of microorganisms in that it can be used for starting the fermentation in a newly prepared solid-fermenter. In this case, biogas is taken from both the active solids fermenter and a continuously operating regeneration fermenter for the percolate, which serves as a percolate container.

From the WO 02/06439 A2 For example, a bioreactor for methanization of biomass and a biogas plant for generating thermal, electrical or mechanical energy from biomass with a corresponding bioreactor is known. In this application, it is described that the leaking from the formed as a pit fermenter biogas reactors seepage with respect to their pH, their Nutrient content and other important parameters. Additives are then added to the seepage fluids and the seepage fluids processed in this way are used as percolate.

The sequence of the various phases in the biogas production has the consequence that the production of biogas just at the beginning or after a refilling of the fermenter with stackable biomass requires a certain start-up time to provide sufficient for a further application biogas stream or methane stream. During this phase, the gas production increases only slowly and the methane content is low. Furthermore, the biogas production rate at the end of the fermentation usually decreases, inter alia, due to the decomposition, but the methane content is often high.

Correspondingly, the course of biogas production approximates the course of a Gaussian normal distribution (bell curve). During the initial and final phases, the low production and quality of biogas for further utilization or application is often insufficient and affects the quality of the biogas stream of the entire biogas plant, which usually has several interconnected fermenter boxes, which are each operated in different stages of the fermentation process. Accordingly, the biogas produced in the respective solid fermenters in the initial and final phases is often discharged as a lean gas into the atmosphere or burned by a torch with supporting gas. Consequently, due to the inefficient process, an undesirable downtime of the solid-fermenter can occur, which can be associated with high costs.

Furthermore, in conventional processes and fermenters there is the problem that they are not only intended for a certain amount, but also a certain type of biomass. For example, in solid fermenters exclusively stackable biomass is utilized, with liquid fermenters preferably being supplied to liquid biomass or biomass having a high degree of degradation (for example corn silage and food particles). For liquid biomass is also a permanent mixing with large volume of, inter alia percolate (or liquid fermentation medium of a liquid fermenter) required to ensure sufficient efficiency of biogas production. Accordingly, both processes (liquid fermentation and solid-state fermentation) are carried out separately and in dedicated specialized fermenters. However, if only a small amount of liquid biomass is present, the cost of providing its own liquid fermenter is too high. Consequently, in such cases, the existing liquid biomass is simply disposed of or distributed to agricultural land.

Both methods can thus result in a low efficiency of biogas production and at the same time a high environmental impact. Accordingly, there is a need to make the utilization of biomass more efficient and environmentally friendly, in particular to compensate for fluctuations in the biogas volume and / or methane content and to ensure a relatively constant biogas volume flow at relatively constant methane content.

The DE 10 2013 102 642 A1 shows a method for the production of biogas, wherein a solid fermenter chamber is provided for the fermentation of stackable biomass, wherein percolate is repeatedly applied to the stackable biomass in the solid fermentation chamber and the percolate is produced from the fermentation substrate of a Flüssigfermentationsanlage.

The DE 10 2012 109 821 A1 shows a method and apparatus for generating biogas, wherein at least one solid fermenter for the fermentation of organic matter and at least one percolate tank is provided, wherein percolate is discharged from the solid fermenter, fed to the percolate tank and recycled from this into the solid fermenter.

Through the websites "https://web.archive.org/web/20160319005350/http://www.renergon.ch/rsdupgrade-feststoff-fermentation" and "https://web.archive.org/web/2016Q319003230/ http://www.renergon.ch/vorteile-biogas-rsdtechnologie-renergon "is disclosed to extend an existing liquid fermentation plant by a separately acting solid-fermenter.

It is also known to use a combination of discontinuous solid-state fermentation and separately provided continuous liquid fermentation for the production of biogas according to the website "https://web.archive.org/web/20160319005015/http://www.renergon.ch/rsdmini -solids-liquids ".

Presentation of the invention

Based on the known state of the art, it is an object of the present invention to further optimize the gas yield in a solid-fermenter in order to be able to optimally utilize the plant capacities and the biomass to be fermented.

This object is achieved by a method for producing biogas in a solid-fermenter having the features of claim 1. Advantageous developments emerge from the subclaims.

Accordingly, a method for producing biogas in a solid fermenter is proposed in which percolate is applied to stackable biomass in order to produce biogas in a fermentation process, wherein liquid biomass is additionally applied to the stackable biomass.

The stackable biomass that can be introduced into a solid-phase fermenter can have very different dry substance contents. Liquids or free water are not introduced into the solid-fermenter due to the filling method (wheel loader). In particular, the stackable biomass organic, high-fiber solids, wherein the composition, the porosity, the energy content and the fiber content can usually vary from load to load. However, the stackable biomass has such a structure that it can be stacked and deformed.

The liquid biomass may be a low-solids, preferably high-energy and / or homogeneous liquid. Usually, however, the liquid biomass consists of an emulsion, dispersion and / or suspension, which generally has a higher viscosity than water and in particular a gel-like structure. The liquid biomass may also comprise parts and / or particles of a solid, which are produced, for example, by comminution, dismemberment and / or chopping biomass and admixed with the liquid biomass and applied to the stackable biomass. Preferably, liquid biomass is applied which has liquid, organic and / or viscous residues. Accordingly, the liquid biomass may contain liquids of various kinds, for example from the processing industry, agriculture or gastronomy. In particular, the liquid biomass may contain oily effluents, e.g. Palm oil mill effluent (POME) of the palm oil industry, frying oil or other conventional oils from the gastronomy sector as well as glycerine (residue of biodiesel production).

Preference is given to the solid bed of those fermenter (s) liquid biomass applied whose biomass was already involved about 1 week in the fermentation process. After this time, biofilms have been formed on the structurally rich biomass in the fermenter, whereby 5-7 days usually pass for the formation of mature / active biofilms. Due to the formation of the biofilms on the structurally rich biomass, a large volume of metabolically active microorganisms is present on the solid bed, which are organized in biofilms and which simultaneously have a large surface area due to the distribution on the solid bed. This results in synergy effects in the fermentation of high-fiber material and high-energy liquid biomass. This also has a positive effect on the degree of degradation of the fiber-rich material as the microorganisms receive more readily available energy, thereby increasing their growth and metabolic rate, thereby promoting the degradation of fibrous material.

Furthermore, it is provided that the application of the liquid biomass can be carried out continuously, cyclically and / or pulsatingly and / or over a period of between 1/24 or one hour and 7 days, preferably between 2 and 5 days, particularly preferably 3 days.

However, the application of the liquid biomass can also be carried out directly at the beginning or after the filling of the solid fermenter with stackable biomass. Accordingly, the liquid biomass is applied at once from above onto the stackable biomass, wherein the liquid biomass slowly penetrates down into the stackable biomass or infiltrates. This application method has, inter alia, the advantage that in this regard no further regulations or devices are required.

However, a continuous, cyclic and / or pulsating application has, inter alia, the advantage that the stackable biomass is already soaked through a first application process and thus an improved distribution and supply in the different layers with high-energy liquid biomass is ensured even in further application processes.

For example, a continuous application may be provided at a low volume flow of liquid biomass, which, in contrast to a single application, on the one hand better preserves the structure of the stackable biomass and, on the other hand, also continuously supplies the upper layers of the stackable biomass with high-energy liquid biomass.

A cyclic or periodic application has, inter alia, the advantage that an intended exposure time can be maintained and allows a better mixing of the liquid biomass with the resulting degradation products, biological factors and the percolate. The liquid biomass can also be applied with a variable volume flow. Likewise, the liquid biomass can be applied in different phases in order to avoid flattening of the biogas production, for example after a certain residence time (end of the fermentation process), or to increase the biogas production of an already very productive solid fermenter. One pulsating application can continue to be both continuous and cyclic. In particular, the duration and the amount during the pulsating application can be adjusted such that it is adapted, for example, to the growth and / or the metabolic rate of the microorganisms or the degree of degradation of the stackable biomass.

The application of the liquid biomass preferably takes place over a period of between one hour and 7 days, preferably between 2 and 5 days, particularly preferably 3 days. The cyclic or pulsating application described above can also be provided, for example, in minute intervals or hourly intervals. In contrast to a single application has the application over a period of time, inter alia, the advantage that dehydration and in particular the emergence of phases are prevented with low-energy liquid biomass.

The application of the liquid biomass can also take place separately from the percolate. For example, only liquid biomass and, for a different period of time, only percolate can be applied to the stackable biomass over a given period of time. These different time periods can either be consecutive or immediately adjacent or temporally spaced.

In order to promote the effect of the liquid biomass, a percolate discharge and / or percolate return of the solid fermenter is preferably closed during the application and / or after the application of the liquid biomass. Accordingly, both the liquid biomass and the percolate in the solid-fermenter can stay longer in order to be converted into biogas as far as possible. The percolate cycle is consequently interrupted or closed at least during the application and preferably after the application of the liquid biomass.

This has the advantage, inter alia, that the liquid, in particular the liquid biomass and the seepage liquors, collect at the bottom in the solid-fermenter, so that they can react longer with the stackable biomass and penetrate better into the stackable biomass. In addition, due to the excess amount of energy-rich biomass acids, which reduce the pH and cause acid hydrolysis of existing in the solid-fermenter stackable biomass. Consequently, the acidic, hot-humid environment also attacks, for example, difficult-to-digest plant fibers such as lignocelluloses. By means of such a chemically biological pretreatment not only an optionally required mechanical treatment technology can be bypassed, but also the production of biogas during a first phase or after the filling of the solid-fermenter can be improved.

Preferably, after the application of the liquid biomass, a residence time of the applied liquid biomass in the solid-state fermenter is between 1 and 7 days, preferably between 2 and 5 days, particularly preferably 3 days. The residence time is preferably predetermined based on the quality, particularly preferably on the basis of the biogas volume, the biogas volume flow, the methane gas content and / or the residual gas content of the biogas produced.

The intended residence time has, inter alia, the advantage that the decomposition or fermentation of the stackable biomass is promoted by a longer interaction with the percolate and the liquid biomass. Accordingly, a chemical biological pretreatment takes place in the solid-fermenter without an otherwise required external storage and / or mechanical treatment technology. The thus improved and accelerated fermentation process thus increases the efficiency and in particular the biogas production of the solid fermenter, especially at the beginning of the fermentation process or after a refilling of the solid fermenter. The intended residence time of the liquid biomass supports or facilitates the formation of an acidic, moist-hot environment described above. Acid hydrolysis is not only not intended in conventional processes and solid-state fermenters, but is also avoided explicitly by flushing with a percolate stream. Rather, the focus in conventional methods is on a continuous percolation of solid biomass. However, such an acidic hydrolysis has the particular advantage that both at the beginning and at the end of the fermentation process a high quality and a high volume flow of the biogas produced are ensured.

Accordingly, the liquid biomass can be applied to the stackable biomass at the beginning of the fermentation process. An application of the liquid biomass during an initial phase or after refilling the solid fermenter with stackable biomass has the advantage, inter alia, that the biogas production is promoted by the immediate supply of high-energy liquid biomass and the residence time of the liquid biomass acid hydrolysis or the solids fermenter responds faster. Accordingly, for example, both the biogas volume produced and the methane content are increased even in an initial phase.

The application of the liquid biomass can furthermore be provided after an initial phase or at the end of a start-up phase, wherein the stackable biomass is preferably percolated in the initial phase. This has, inter alia, the advantage that the adhesion of the liquid biomass to the stackable biomass and the penetration of the liquid biomass into the stackable biomass during the application of the liquid biomass is improved. Furthermore, this has the advantage that the stackable biomass is already involved in the fermentation process and correspondingly mature and / or active biofilms have formed on structurally rich biomass in the started Feststofffermenter. Consequently, a large volume of metabolically active microorganism solids bed is provided to the liquid biomass. Thus, by increasing the biogas production in, for example, a fermenter box, the low gas yield of another fermenter box (which is, for example, at the beginning or end of the process) can be compensated. This allows a constant yield of biogas to be achieved over the entire plant.

Optionally, the application may also be provided at a different time or at several points in time of the fermentation process. For example, the application of the liquid biomass may take place in phases and / or at the end of the fermentation process in order to prevent, for example, stabilization or reduction of biogas production.

The application of the liquid biomass, in particular at a designated residence time of the liquid biomass, thus causing a large volume of gas is ensured at high methane content and the biomass used is almost completely implemented within the intended fermentation due to the high degree of degradation, leaving almost no unused digestate. Likewise, the residence time of the biomass present in the solid-fermenter can be prolonged by applying or feeding in the liquid biomass in such a way that stabilization or reduction of the biogas production is prevented and the efficiency and yield of the solid-fermenter or of the biogas plant is increased.

To ensure, for example, a continuous gas yield of the biogas plant, the application of the liquid biomass, preferably the duration, frequency, dosage and / or type of application, based on the quality, preferably based on the biogas volume, the biogas volume flow, the methane gas content and / or the residual gas content of generated biogas, regulated.

The fact that the application of the liquid biomass is regulated by the quality of the biogas produced, the yield of usable biogas can be optimized. In contrast to the controls known from the prior art, which control the operating parameters of a solid fermenter based on predetermined, largely rigid pattern, can be achieved via the proposed scheme and the associated feedback mechanism that at any given time or in any given period of the solid fermenter operated in an optimized area.

The quality of the biogas produced is understood to mean the volume of biogas produced, the biogas volume flow generated, the methane gas content and / or the residual gas content in the biogas produced. Other parameters in the biogas produced can also be used as a controlled variable for controlling the application of the liquid biomass, such as, for example, the variation of the biogas volume flow or the methane gas content.

By controlling the biogas quality produced, for example, to a given proportion of methane gas, over a longer period of time, a constant yield of methane gas can be achieved, whereby the subsequent recovery is simplified. For example, the combustion in a downstream cogeneration plant (CHP) is simplified if there is a constant proportion of methane gas in the supplied biogas.

In the start phase or initial phase of a solid fermenter, for example, directly after closing the gas-tight door, a quick start of the fermentation process can be achieved via the scheme, since the quality of the withdrawn biogas is used as a controlled variable. Accordingly, the application of the liquid biomass in the starting phase of the fermentation process can be regulated so that the withdrawn biogas follows a predetermined quality course. In particular, for example, the frequency, the amount and / or the duration of the application can be regulated so that the fermentation of the biomass is optimized even in an initial phase. Operating parameters of the solid fermenter can also be selected accordingly, for example, not only to allow acid hydrolysis and thermophilic operation but preferably to promote.

Thus, even in the starting phase of the fermentation process can be addressed directly to different loads of the solid fermenter without the specific composition of the load must be known. Usually, the stackable biomass that can be introduced into a solid-fermenter varies from load to load in terms of its composition, its porosity, its energy content, its fiber content and its moisture content. About the largely rigid Control pattern of the prior art can not be taken into account these different circumstances.

However, this is taken into account by the proposed regulation, which uses gas quality as a controlled variable. Accordingly, the fermentation process of the entire plant is operated by the controlled application of the liquid biomass (in one or more solid fermenter) and the variation of the operating parameters in such an optimized range that the withdrawn biogas follows a predetermined desired course of the controlled variable and can be independent of the respective load the solid fermenter, the gas yield can be optimized.

Furthermore, the fermentation of stackable biomass in a solids fermenter is a biological process which is not fully predictable and accordingly not optimally exploitable via a rigid control pattern. The proposed regulation can also take into account these deviations in the fermentation process, which may vary from solid-fermenter to solid-fermenter in a biogas plant, and which may vary from loading to loading, and nevertheless an optimized fermentation process is always achieved.

Thus, the biogas quality is used as a control variable, so for example, the generated biogas volume or the biogas volume flow, the methane gas content and / or the residual gas content, and the target controlled variable is guided via a guide along the optimal dynamic course of Vergärvorganges.

The lead size can either be predefined for a given solid-fermenter or else be formed on the basis of further parameters, such as the composition of the biomass introduced into the solid-fermenter, the previous residence time, the amount of introduced biomass and / or the current fermentation state to carry out further optimization of the fermentation process.

In this way, a constant biogas quality can continue to be achieved in interaction with the other solid fermenters of a biogas plant, since the individual solid fermenters follow a predetermined course in the biogas quality and accordingly the biogas mixed together from all active solid fermenters over time can always have a consistent quality.

For example, the amount of liquid biomass to be applied in a solids fermenter can be adjusted on the basis of the quality of the biogas produced in order to compensate for the low methane production then occurring in one of the solids fermenters in an initial phase or final phase of the fermentation process. Accordingly, by further application of the liquid biomass biogas production in the entire system can be stabilized. Likewise, after an initial phase or start-up phase, liquid biomass can be applied in order, for example, to compensate for a failure of the biogas production of another solid fermenter, for example during refilling, with a short-term higher biogas production in the respective solid fermenter.

The liquid biomass applied in an application process preferably corresponds to between 0.1 and 20 percent, preferably between 1 and 10 percent of the mass of the stackable biomass.

The mass or quantity of the liquid biomass, in particular, represents an upper limit for a given time unit, which, depending on the requirement and configuration of the biogas plant, can be varied between one day and one year or 365 days. Preferably, the upper limit of the amount of liquid biomass applied in an application process is one year.

The structure of the solid bed in the solid fermenter serves as a matrix for the fermentation and degradation of the liquid biomass.

In order to promote the fermentation process and biogas production, the stackable biomass is preferably percolated before and / or after application of the liquid biomass.

One of the advantages of percolating the stackable biomass before applying the liquid biomass is that the large volume of metabolically active microorganism solid bed or biofilms provided before the application of the liquid biomass and percolation is directly supplied with high-energy liquid biomass when the liquid biomass is applied. The acidic hydrolysis and / or the fermentation process are thus promoted.

The advantage of percolating the stackable biomass after the application of the liquid biomass is, inter alia, that the fermentation process and the biogas production are further increased. The liquid present in the solid-fermenter is first discharged and preferably passed through a percolate return into the already existing percolate circulation. The liquid biomass has already decomposed, so that only residual proportions are fed to the percolate circulation, which is then in the proposed percolate tank can decompose without a layer in the percolate tank will accumulate.

It is further provided that the percolation, such as the application of the liquid biomass, can be continuous, cyclic and / or pulsating. For example, percolation can be phased to ensure a sustained supply of active percolate and to promote the fermentation process.

In addition, the composition of the percolate, which is provided for sprinkling the stackable biomass in the Feststofffermenter vary, for example, with respect to its loading with microorganisms, which ultimately leads to the formation of the biogas-producing biofilms in the biomass.

In order to simplify the application of the liquid biomass, it may further be provided that the liquid biomass is added to the percolate. The liquid biomass is preferably added in a predetermined amount which corresponds to between 0.1 and 20 percent, preferably between 1 and 10 percent of the stackable biomass.

By incorporating the liquid biomass into the percolate, existing conduits and applicators can be used and feeding can be simplified. Costly additional installations, modifications and / or components can thus be dispensed with. Preferably, the liquid biomass is added to the percolate upstream of the percolate feed or between a percolate tank and a feed arrangement of the solid fermenter. This has the advantage on the one hand that no separate lines are required or can largely be dispensed with, on the other hand that the liquid biomass already mixed before application to the stackable biomass with the percolate and a uniform distribution and optionally further liquefaction of the liquid biomass are guaranteed. The amount of liquid biomass, as described above, preferably corresponds to an amount for a given time unit or for a fermentation process.

In a particularly preferred variant, the application of the liquid biomass and / or the fermentation process are regulated by means of at least one operating parameter of the solid fermenter. As directly accessible operating parameters are in particular the solid-fermenter temperature, the amount of applied percolate, the pressure, the gas mixture, the partial gas pressure, the amount, the pH, the composition, the previous residence time and / or the fermentation state of the recorded in the solid fermenter Biomass suitable. Likewise, other directly accessible parameters which can be used as manipulated variables in the proposed regulation are conceivable.

In order to promote the fermentation process, in particular the thermophilic operation of the solid fermenter, a storage tank and / or a feed tank of the liquid biomass is preferably tempered. This can be done in particular by a respective arrangement in a Feststofffermenteranlage and / or at a combined heat and power plant. For example, the heat of a combined heat and power plant or the heat of an adjacent solid fermenter or an external heat source such as solar thermal or process heat for temperature control can be used to temper a storage tank or feed tank and to ensure a required and / or predetermined flowability of the liquid biomass.

If a plurality of solid fermenters are present in a biogas plant, it can further be provided in a further preferred embodiment of the method that the regulation of the application of the liquid biomass and / or the fermentation process is carried out separately and independently of the other solid fermenters for each solid fermenter in a biogas plant. At least two solids fermenters are preferably simultaneously controlled on the basis of the quality of the mixed gas stream of all biogas streams.

The regulation of the respective fermentation process based on the quality of the biogas produced takes place separately for each individual solid fermenter of a biogas plant. Accordingly, the course of a respective fermentation within a solid fermenter for two solids fermenter within a biogas plant run completely different, depending on which biomass mix the respective solid fermenter were loaded, and which other external parameters intervene in the respective fermentation process. However, the two different courses of fermentation in the respective solid fermenters lead in both cases to an optimization of the yield of biogas and in particular to an optimization of the yield of methane in the respective fermentation process, so that after completion of the fermentation process the best possible biogas production was achieved.

Also, the amount of liquid biomass to be applied in a solids fermenter can be adjusted based on the quality of biogas produced to reduce methane production, e.g. In an initial phase or final phase of the fermentation process, during refilling or by a lesser amount of the introduced stackable biomass, in another Compensate solid fermenter. Preference is given to the total gas flow over the entire system or biogas plant is detected, wherein the liquid biomass is applied in accordance with the respective solids fermenters by feedback or fed. Accordingly, further application of the liquid biomass stabilizes the biogas production in the entire plant, optionally optimizing it and ensuring a continuous volume flow of the biogas produced. Thus, the biogas yield emitted from a biogas plant can be regulated with regard to the quality of the biogas in order to achieve a constant biogas quality from the interplay of the individual solid-matter fermenters.

Furthermore, a device for generating biogas with the features of claim 13 is proposed. Accordingly, the device comprises at least one solid-matter fermenter for receiving stackable biomass, wherein the stackable biomass can be flowed through by a percolate stream in order to produce biogas in a fermentation process. According to the invention, a regulation for regulating the fermentation process is provided, which is set up to additionally apply liquid biomass to the stackable biomass.

In this case, at least one liquid biomass container, liquid biomass container part, storage tank and / or feed tank of the liquid biomass is preferably provided, wherein the control is set up to add liquid biomass to the percolate, preferably upstream of the percolate supply.

A Flüssigbiomassebehälter or storage tank can have a sensor to control the level. This has, inter alia, the advantage that, for example, the amount of liquid biomass present can be detected even in the case of irregular deliveries and / or quantities.

The liquid biomass can also be stored in barrels or similar containers. This can be advantageous in particular with regular delivery, wherein the barrels can preferably be used or used directly for the respective fermenter. Accordingly, the barrels preferably have predetermined standard dimensions, so that they are stackable, they can be used without further modifications and the amount of liquid biomass present emerges directly from the number of barrels.

In order to ensure the fluidity of the liquid biomass, a heating device or heating arrangement can furthermore be provided, so that the liquid biomass can be fed in, for example, even at low temperatures. For this purpose, an already existing temperature of a percolate tank can be used. Preferably, the liquid biomass is tempered by an arrangement of the liquid biomass container, for example by utilizing the waste heat of a combined heat and power plant.

For the application or the feeding of the liquid biomass, one or more pumps can furthermore be provided. To this end, peristaltic pumps and rotary lobe pumps are preferably used. For example, while a peristaltic squeeze pump is preferably used to deliver the liquid to the percolate line, a rotary lobe pump on the suction side may pump off the liquid present in the solids fermenter and convey it to the percolate tank and / or percolate loop. Both peristaltic pumps and rotary lobe pumps, optionally with a throttling function, are often already present in conventional solid fermenters, so that further additional installations for the application of liquid biomass are not required.

The regulation or control can furthermore regulate in particular the application of the liquid biomass to the stackable biomass. For example, a metering valve and / or a pump supply may be provided, which are in communication with the control. In particular, the Feststofffermenter may have a level detector, such as a pressure sensor or a pressure probe to detect the amount of liquid present in the solid fermenter and to regulate the application of liquid biomass on the scheme.

By applying the liquid biomass, a longer residence time of the biomass in the solid-fermenter can correspondingly be provided, so that a corresponding amount of stackable biomass can be introduced into the solid-fermenter during refilling. In order to take this into account, a buffer may preferably be provided during plant dimensioning.

In order to provide an improved distribution of the liquid biomass, the control can be set up to apply liquid biomass to the stackable biomass by means of a dispensing arrangement common to the percolate, preferably at least one spray nozzle and / or one metering valve. The application is preferably carried out by spreading, misting or raining. As a dispensing arrangement, for example, a nebulizer, a shower or just a line drain can be provided.

For the determination of the quality of biogas withdrawn from a solid - fermenter, Furthermore, at least one sensor which regulates the regulation of the fermentation process and / or the application of the liquid biomass may be provided at least one of the solid fermenter temperature, the pressure, the gas mixture, the partial gas pressure, the fermentation state or the pH of the biomass received in the solids fermenter.

Preferably, a sensor is provided for determining the quality of the withdrawn from a solid fermenter biogas, which regulates the regulation of the application of the liquid biomass. For example, the sensor may be designed as a gas sensor in order to determine one or more gas fractions, the gas volume and / or the generation rate. It can also be provided that a partial or a total pressure is measured. In addition or as an alternative to a gas sensor, the temperature and / or the pH of the liquid present in the solid-fermenter can also be determined by means of a corresponding sensor. The measurements can be done manually, but are preferably detected automatically, in particular cyclically. Consequently, the measurements can be used as feedback to control the application of the liquid biomass and / or the fermentation process directly or via a control.

Furthermore, it can be provided that the control acts on the temperature in the fermenter on the percolate temperature, the heating temperature of the percolate, percolation time, percolation frequency, the amount of applied percolate and / or the pH of the percolate as a control variable, and / or the scheme is set up to the fermentation process, the biomass with percolate, the percolation, the amount of percolate and / or percolation frequency based on the quality, preferably based on the biogas volume, the biogas volume flow, the methane gas content and / or the residual gas content of the biogas produced regulate, and the parameter preferably serves as a controlled variable.

list of figures

• 1 zeigt schematisch eine Vorrichtung zur Erzeugung von Biogas mittels des beschriebenen Verfahrens;
• 2 zeigt schematisch den Regelkreislauf in einer Biogasanlage; und
• 3A bis 3G zeigen schematisch Aufbringungsverläufe der Flüssigbiomasse und der Perkolierung.

Preferred further embodiments and aspects of the present invention are explained in more detail by the following description of the figures.

• 1 schematically shows a device for generating biogas by means of the described method;
• 2 schematically shows the control circuit in a biogas plant; and
• 3A to 3G show schematically application curves of liquid biomass and percolation.

Detailed description of preferred embodiments

In the following, preferred embodiments will be described with reference to the figures. In this case, identical, similar or equivalent elements in the different figures are denoted by identical reference numerals and a repeated description of these elements is partially omitted in order to avoid redundancies in the description.

In 1 is a biogas plant 1 to carry out the process for the production of biogas shown.

A first solid fermenter 20 and a second solid-fermenter 22 are exemplary in the biogas plant 1 provided, in each of which stackable biomass can be included for fermentation. Usually in a biogas plant 1 a larger number of solid fermenters provided, for example, 3 to 12. The Feststofffermenter 20 . 22 are constructed in a known manner and have in particular gas-tight walls, floors and ceilings, as well as a gas-tight closing gate, through which the respective Feststofffermenter 20 . 22 is charged with organic solids and through which the fermentation residue is cleared out or discharged after completion of the fermentation process.

Furthermore, a percolate tank 3 provided in which percolate can be added and which serves as Perkolatspeicher accordingly. The percolate is passed over percolate nozzles arranged in the solids fermenters 44 . 46 applied to the biomass.

From the percolate tank 3 is via the Perkolatleitung or Perkolatzufuhr 42 Percolate so in the respective Feststofffermenter 20 . 22 passed that over it to the ceiling of the solid-fermenter 20 . 22 provided percolate nozzles 44 . 46 on the organic solids, which are within the Feststofffermenter 20 . 22 are arranged, can be drizzled. The percolate collects at the bottom of the solid fermenter 20 . 22 after it has passed through the organic solids. Therefore, in the bottom area of the solid fermenter 20 . 22 corresponding Perkolatleitungen or discharge lines 40 provided with the percolate tank 3 are connected, so that on the bottom of the respective Feststofffermenter 20 , 22 collected percolate over the percolate line 40 back to the percolate tank 3 can be directed.

Accordingly, a Perkolatkreislauf is formed, the percolate from the Perkolattank 3 over the percolate line 42 and the percolate nozzles 44 . 46 into the solids fermenter 20 . 22 is sprinkled, and after passing through the organic solid at the bottom of the Feststofffermenter 20 . 22 is collected and via the percolate line 40 again the percolate tank 3 is supplied.

Furthermore, there are biogas pipes 50 and 52 provided by means of which in the Feststofffermentern 20 . 22 produced biogas can be deducted. In addition, a biogas line 53 provided by means of which in the percolate tank 3 resulting biogas can be derived.

For example, additional percolate volume is produced in the fermentation process by producing water during fermentation (previously bound capillary or cell water released by the decomposition of the structures). Furthermore, additional volumes of water are introduced into the percolate circulation via moist organic solids.

The about the biogas pipes 50 . 52 . 53 derived biogas is subsequently converted either directly in a combined heat and power plant (CHP) into electricity and heat, or it is purified and placed accordingly as biomethane in the market. It can also be provided that the generated carbon dioxide is separated and / or stored, which can be used, for example, for further applications such as cooling, fire protection and / or for increasing anaerobic conditions and corresponding fermentation.

The chemical, physical and / or biological properties of the percolate in the percolate tank 3 be by means of a corresponding sensor 7 measured. The sensor 7 For example, it can measure pH, temperature, FOS / TAC, and other parameters essential to fermentation.

In the schematic representation of 1 are in the biogas lines 50 . 52 , which in the respective Feststofffermentern 20 . 22 produce generated biogas, sensors 80 . 82 provided, which measure the quality of the biogas produced. Here, on the one hand, volume sensors are used by means of which the total amount of biogas produced in a specific solid-fermenter or the volume flow can be determined. On the other hand, for example, sensors 80 . 82 can be used, by means of which the methane gas fraction can be measured in the biogas produced, or it can be a residual gas content can be determined.

On the basis of the measured values of the biogas quality can accordingly over a corresponding regulation 84 For example, the percolation of the respective Feststofffermenter 20 . 22 be managed. This can be done by the scheme 84 according to valves 48 . 49 be controlled in the Perkolatleitungen 42 so that over the Perkolatdüsen 44 . 46 the predetermined percolate amount to the biomass in the respective Feststofffermenter 20 . 22 is applied.

Furthermore, a liquid biomass container 9 intended. In order to apply liquid biomass to the stackable biomass, liquid biomass from the liquid biomass container can accordingly 9 via a valve 47 into the existing percolate line 42 be fed. The valve 47 and thus the feeding of the liquid biomass are from the scheme 84 regulated. While in 1 only a liquid biomass container 9 and a valve 47 after the percolate container 3 and before the diversion of the line 42 However, it is also possible for a plurality of liquid biomass containers and different arrangements, for example after the branching of the line, to be shown 42 , be provided. The liquid biomass containers may be located either upstream or downstream of the valve 47 be arranged and in each case via a valve in the respective Feststofffermenter 20 . 22 and the corresponding nozzles 44 . 46 be coupled. Instead of a diversion of the line 42 can also separate and / or multiple lines 42 be provided.

Similar to the percolate container 3 is for the liquid biomass container 9 at least one sensor 71 provided, which detects the level and as feedback for the scheme 84 is used. It can also be provided that parameters such as temperature, pH value, volume and / or amount of the liquid biomass of the at least one sensor 71 be recorded.

To the in the solid fermenter 20 . 22 to detect existing liquid is in the respective solid fermenter 20,22 at least one sensor 72 . 73 , In particular, a level detector or pressure probe, provided which as a feedback for the control 84 is used. It can also be provided that parameters such as temperature, pH value, and / or chemical composition of the biomass and / or the percolate of the at least one sensor 72 . 73 be recorded.

Consequently, the scheme can 84 the application of the liquid biomass for the respective solid fermenter 20 . 22 governed, for example, on the basis of the measured values of the biogas quality or the residence time. This can be done by the scheme 84 corresponding to the valve 47 and for the respective Feststofffermenter 20 . 22 corresponding valves 48 . 49 in the percolate lines 42 be controlled so that the liquid biomass is added to the percolate and the percolate nozzles 44 . 46 the predetermined amount of percolate and liquid biomass on the stackable biomass in the respective Feststofffermenter 20 . 22 is applied.

As a control variable in the control then the corresponding measured value of the sensor 72 . 73 . 80 , 82, 86 used and compared with a predetermined setpoint of the controlled variable. By way of a corresponding adaptation of one or more operating parameters of the solid-matter fermenter 20 . 22 , which serve as manipulated variable, the controlled variable is returned to the setpoint. If, for example, a drop in biogas production and / or in the methane gas content at a sensor 80 . 82 . 86 is detected, the application of the liquid biomass, in particular the amount and the frequency in the respective Feststofffermenter according to the valves 47, 48, 49 adjusted so that the biogas production is raised again to the predetermined setpoint.

Since the fermentation process and thus the biogas yield goes through different phases, the setpoint of the controlled variable must also be adjusted over the fermentation process in order to achieve optimum utilization of the plant capacities and the biomass used. Accordingly, a reference variable is determined on the basis of the time course and preferably taking into account the composition of the biomass. The reference variable determines the course of the setpoint of the controlled variable accordingly. For example, the biogas yield increases slowly at the beginning of the fermentation process, which can be illustrated by a corresponding course of the reference variable.

At the beginning of the fermentation process, when the still dry biomass must first be inoculated, for example, by measuring the gas quality and the resulting application control of the liquid biomass, an optimized starting behavior of the respective solid fermenter 20 . 22 be achieved. Thus, it may be useful at the beginning of the fermentation process to percolate at shorter intervals, with a correspondingly adjusted percolate amount, in order to achieve good moisture penetration of the freshly introduced into the fermenter biomass. Subsequently, liquid biomass can be applied to the stackable biomass to further promote the fermentation process and biogas production. Due to the then increasing methane gas content in the biogas produced, for example, both the frequency of application and the residence time of the liquid biomass can be regulated. The time when this happens to obtain an optimal biogas yield can be determined by measuring the gas quality.

It has been shown that the regulation of the fermentation process over the actually relevant control variable, namely the methane yield, makes a multiplicity of other control mechanisms superfluous. Other operating parameters such as the pH value or the temperature of the solid fermenter 20 . 22 However, existing liquid can also be used for the control 84 be used.

The of the scheme 84 output control variable in the form of the respective change in the operating parameters of the solid fermenter 20 . 22 leads accordingly to a regulation of the gas quality. Applying the liquid biomass to that in one or both of the solid fermenters 20 . 22 arranged stackable biomass is then triggered accordingly for a predetermined period of time until the controlled variable, so the biogas quality, again the target control variable, ie the desired biogas quality corresponds. This can happen not only during a start phase or start-up phase, but also in the further course of the fermentation process, to a reduced biogas yield in a Feststofffermenter 20 . 22 to compensate.

In a further development or a variant, the biogas quality via a sensor 86 determines which is arranged in a line section in which the biogas streams from all Feststofffermentern 20 . 22 already mixed together. This sensor 86 Measures accordingly the quality of the biogas, which finally from the biogas plant 1 is output, for example, to use it in a combined heat and power plant, or which is supplied to the further processing or treatment for feeding into a gas network. The regulation 84 can also use the quality of the entire generated biogas as a controlled variable and the operating parameters for the individual solid fermenters 20 . 22 use as control variables that the most uniform biogas quality from the biogas plant 1 is issued. The regulation takes this into account 84 also the different fermentation states and residence time of the liquid biomass in the individual solid fermenters 20 . 22 and accordingly gives the reference variable for the individual solid fermenter 20 . 22 so that an optimal gas yield is achieved while maintaining uniform gas quality.

In 2 is shown schematically again the control loop. The two solids fermenters 20, 22 produce biogas, its quality via the sensors 80 . 82 is measured. In particular, the generated biogas volume, the methane gas content and possibly the content of certain residual gases in the biogas stream are determined. The measured values obtained in this way become a central control 84 fed. About the central regulation 84 then the supply of Liquid biomass and percolate via valves 47 . 48 . 49 into the respective solids fermenters 20 . 22 regulated. For example, about the scheme 84 the frequency, amount and / or duration of application of the liquid biomass to the solid bed disposed in the solids fermenter 20,22 are individually controlled separately for each solid fermenter so that in each solid fermenter 20 . 22 the fermentation of the biomass is also optimized in an initial phase. Operating parameters of the solid fermenter can also be selected accordingly, for example, not only to allow acid hydrolysis and thermophilic operation but preferably to promote.

The regulation 84 can additionally with inputs from users, which for example via a keyboard 74 be carried out on certain peculiarities of the respective biomass loading in the individual solid fermenter 20 . 22 be informed. For example, reference may be made to a particular substrate composition, for example a single substrate composition, which possibly would require a changed control behavior. Particularly preferably, the course of the reference variable can be adjusted in this way.

About a database 76 appropriate additional parameters can be queried, which may be of importance for the respective individual fermentation process.

However, the actual application of the liquid biomass is controlled by measuring the quality of the biogas produced, the detected fill level, the fermentation state and / or the residence time of the liquid biomass and / or stackable biomass.

In 3A to 3G schematically exemplary application processes of liquid biomass and percolation are shown. In all the figures, the percolation process (Y-axis, top, solid line) and the application process of the liquid biomass (Y-axis, bottom, dashed line) over time (X-axis) are shown.

As in 3A shown, the stackable biomass is initially only percolated during a first phase I or an initial phase. At the end of this first phase I, liquid biomass is also applied to the stackable biomass. The amount, frequency and / or dosage of the applied liquid biomass are preferably regulated on the basis of a specific biogas quality, the amount of stackable biomass and / or the percolate. Although the percolate cycle or the percolate outlet is preferably opened during the first phase I, it is preferably closed during the application of the liquid biomass, so that the liquid biomass and the percolate accumulate or accumulate in the solid fermenter. Accordingly, a residence time of the liquid biomass and the percolate is provided in a second phase II, so that form due to the excess amount of energy-rich biomass acids, which lower the pH and cause acidic hydrolysis of existing in the solid fermenter stackable biomass. In a third phase III, the percolate discharge or the percolate cycle is reopened, so that the accumulated liquid is discharged again and fed to a percolate container. Accordingly, the stackable biomass is percolated again during this third phase III to promote the fermentation process and biogas production.

However, the application of the liquid biomass can also be carried out directly at the beginning or after refilling and simultaneously with the first application of the percolate, as in 3B shown in the first phase I. However, the frequency of application, and especially the amount of liquid biomass, may be independent of percolation, such that the liquid biomass, for example, is added to the percolate only every other, third, or further application process of the percolate. The solid line and the dashed line indicate only a phase of application, but do not necessarily constitute a continuous application and thus can also represent a cyclic and / or pulsating application.

In 3C The course of percolation and the application of liquid biomass are similar to those in 3A , At the end of the fermentation process, liquid biomass is re-applied during the third phase III in order, for example, to prevent stabilization or reduction of biogas production and to ensure a continuous volume flow. During this phase, the percolate drain can be closed, similar to the first phase I. However, a continuous percolation or an open percolate cycle is preferred. Accordingly, compared to the first phase I, the amount of liquid biomass can be reduced and a stronger nebulization be provided so that after leakage no liquid biomass or only residual components are fed to the percolate cycle and no layer will accumulate in the percolate tank.

Also, one or more application processes of the liquid biomass may be provided as in 3D shown. Usually, the generation of biogas between the first or second phase I, II and the end of the third phase III is predominantly continuous or stationary. However, an intermediate reduction in biogas production in the particular solid-fermenter or in another solid-fermenter, for example after a refilling or during the discharge of the fermentation residues, can be compensated during the third phase III by a further application of high-energy liquid biomass, so that a continuous volume flow and a corresponding biogas quality is guaranteed. Accordingly, the efficiency of, for example, a cogeneration plant existing in the biogas plant is increased and minimizes the risk of failure.

3E shows how the liquid biomass can also be applied separately or separately from the percolate on the stackable biomass. First, the stackable biomass, similar to in 3A , in a first phase I percolated. However, the liquid biomass is not applied at the end of this first phase I, but after the first phase or subsequently to the stackable biomass. It may be provided that the liquid biomass is fed into the existing Perkolatleitung, but the liquid biomass can also be introduced by means of a separate supply line in the Feststofffermenter and applied to the stackable biomass. While the percolate cycle or the percolate outlet of the first phase I is preferably opened, this is preferably closed during the application of the liquid biomass, a residence time of the liquid biomass and the percolate is provided in a second phase II and the stackable biomass during the third phase III again percolated to promote the fermentation process and biogas production, similar to for example 3A ,

3F differs from 3E in that the application of the liquid biomass does not take place immediately after the first phase I but with a time delay.

Furthermore, it can be provided that the application of the liquid biomass can be applied separately or separately from the percolate and before the first phase I or before the first percolation onto the stackable biomass, as in US Pat 3G shown.

As far as applicable, all the individual features illustrated in the individual embodiments can be combined and / or exchanged without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1

biogas plant

20

first solid fermenter

22

second solids fermenter

3

Perkolattank

40

Perkolatzufuhr

42

Perkolatleitung

44

Perkolatdüse the first solid fermenter

46

Perkolatdüse the second solid fermenter

47

Valve for feeding liquid biomass

48

Percolate valve of the first solid fermenter

49

Percolate valve of the second solidified fermenter

50

Biogas line of the first solids fermenter

52

Biogas line of the second solids fermenter

53

Biogas line of percolate tank

7

Sensor of percolate tank

71

Sensor of the liquid biomass container

72

Level sensor of the first solids fermenter

73

Level sensor of the second solids fermenter

74

keyboard

76

Database

80

Gas sensor of the first solid fermenter

82

Gas sensor of the second solid fermenter

84

regulation

86

Gas sensor of the biogas plant

9

Liquid biomass tank

Claims (17)

Process for the production of biogas in a solid-state fermenter in which percolate is applied to the stackable biomass in order to produce biogas in a fermentation process, characterized in that liquid biomass is additionally applied to the stackable biomass. Process for the production of biogas in a solid fermenter according to Claim 1 , by characterized in that the application of the liquid biomass is carried out continuously, cyclically and / or pulsating, and / or wherein the application of the liquid biomass preferably over a period between 1/24 and 7 days, preferably between 2 and 5 days, particularly preferably 3 days. Process for the production of biogas in a solid fermenter according to Claim 1 or 2 , characterized in that the application of the liquid biomass takes place at the same time or separated from the percolate. Process for the production of biogas in a solid-fermenter according to one of the preceding claims, characterized in that the solid-fermenter, preferably a percolate discharge and / or a percolate cycle of the solid-fermenter, is closed during the application and / or after the application of the liquid biomass. Process for the production of biogas in a solid fermenter according to one of the preceding claims, characterized in that, after application of the liquid biomass, a residence time of the applied liquid biomass in the solid fermenter between 1 and 7 days, preferably between 2 and 5 days, particularly preferably 3 days provided is, wherein the residence time is preferably based on the quality, more preferably based on the biogas volume, the biogas volume flow, the methane gas content and / or the residual gas content of the biogas produced, is specified. A method for producing biogas in a solid fermenter according to one of the preceding claims, characterized in that the application of the liquid biomass, preferably the duration, frequency, dosage and / or type of application, based on the quality, preferably based on the biogas volume, the biogas volume flow, the Methane gas content and / or the residual gas content of the biogas produced, is regulated. A method for producing biogas in a solid-fermenter according to one of the preceding claims, characterized in that the liquid biomass applied in an application process corresponds to between 0.1 and 20 percent, preferably between 1 and 10 percent of the stackable biomass. Method for producing biogas in a solid-fermenter according to one of the preceding claims, characterized in that the stackable biomass is percolated before and / or after the application of the liquid biomass. A method for producing biogas in a solid fermenter according to one of the preceding claims, characterized in that the liquid biomass is added to the percolate, preferably in a predetermined amount, which corresponds to between 0.1 and 20 percent, preferably between 1 and 10 percent of the stackable biomass , Method for producing biogas in a solid-fermenter according to one of the preceding claims, characterized in that the application of the liquid biomass and / or the fermentation process based on at least one operating parameter of the solid fermenter, preferably based on the Feststofffermentertemperatur, the amount of applied percolate, the pressure, the gas mixture , the partial gas pressure, the amount, the pH, the composition, the previous residence time and / or the fermentation state of the biomass received in the solid-fermenter. A method for producing biogas in a solid fermenter according to one of the preceding claims, characterized in that the Feststofffermenter, a storage tank and / or a feed tank of the liquid biomass is heated, preferably by an arrangement in a Feststofffermenteranlage and / or at a combined heat and power plant. Process for the production of biogas in a solid fermenter according to one of the preceding claims, characterized in that for each solid fermenter in a biogas plant, the regulation of applying the liquid biomass and / or the fermentation process is carried out separately and independently of the other solid fermenters, wherein preferably at least two solids fermenter be regulated simultaneously due to the quality of the mixed gas flow of all biogas streams. Apparatus for generating biogas, comprising at least one solid fermenter for receiving stackable biomass, wherein the stackable biomass is flowed through by a Perkolatstrom to produce biogas in a fermentation process, wherein the at least one solid fermenter via at least one Perkolatleitung with at least one Perkolatbehälter for generating the Perkolatstroms is connected, characterized in that at least one separate from the percolate container Flüssigbiomassebehälter, Flüssigbiomassebehälterteil, storage tank and / or feed tank of a liquid biomass is provided, wherein the separate Flüssigbiomassebehälter, Flüssigbiomassebehälterteil, storage tank and / or feed tank with at least one Perkolatleitung in Communication, and wherein a regulation is provided for controlling the fermentation process, which is arranged to additionally apply liquid biomass to the stackable biomass, the control is set to the liquid biomass from the liquid biomass container, liquid biomass container part, storage tank and / or feed tank to the percolate. Apparatus for producing biogas according to Claim 13 characterized in that the control is arranged to add liquid biomass to the percolate upstream of the percolate feed. Device according to Claim 13 or 14 , characterized in that the control is set up to apply liquid biomass to the stackable biomass by means of a dispensing arrangement common to the percolate, preferably a spray nozzle and / or a metering valve, preferably to distribute, atomise or sprinkle it. Device according to one of the Claims 13 to 15 characterized in that at least one sensor is provided for determining the quality of biogas withdrawn from a solid fermentor or the overall plant, the solid-fermenter temperature, pressure, gas mixture, partial gas pressure, fermentation state or pH of the biomass received in the solid-fermentor, and regulating the fermentation process and / or the application of liquid biomass. Device according to one of the Claims 13 to 16 , characterized in that the control of the temperature in the fermenter on the percolate temperature, the heating temperature of the percolate, the percolation time, the Percolation frequency, the amount of applied percolate and / or the pH of the percolate acts as a manipulated variable, and / or wherein the Regulation is set to regulate the fermentation process, the exposure to biomass with percolate, the percolation time, the amount of percolate and / or percolation frequency based on the quality, preferably based on the biogas volume, the biogas volume flow, the methane gas content and / or the residual gas content of the generated biogas , and the parameter is preferably used as a controlled variable.

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