DE202008006843U1 - Device for stock preparation for a biogas plant - Google Patents

Abstract

Impact mill with a housing and receiving a biomass furnish as a starting substrate Sieve basket, fixed in the rotating grinding / crushing tools in a variable speed rotor for conditioning the starting substrate to a product substrate, in particular for mechanical treatment, are arranged, characterized in that a closed Strainer basket (112) with a funnel (110) having a milling chamber (108) with a starting substrate (1) (biomass formulation), force-conditioning grinding circle (114) formed, wherein the product substrate (1 ') only by passing the Siebkorbes (112) leaves the grinding chamber (108) and the grinding chamber (108) while Forced conditioning from inside or inside and outside process fluid (2) can be fed.

Description

The The invention relates to a device for stock preparation for a biogas plant. In this context, a process for stock preparation for one Biogas plant and the use of the device described.

Biogas or digester gas is a gas mixture of mainly methane (about 50-70%) and carbon dioxide (about 30-50%) with small amounts of hydrogen sulfide, nitrogen, hydrogen, ammonia and carbon monoxide. It is produced during biodegradation processes under exclusion of oxygen. As a high-quality and CO ₂ -neutral energy source, it can be used as an ecologically and economically sensible source of energy.

Known is to use a fermenter as the central component of a biogas plant. In these biomass, the fermentation substrate is introduced continuously, which previously stored and pretreated.

Under Oxygen termination becomes the substrate with the help of various bacterial strains in a multi-stage anaerobic degradation process to biogas and residues transformed. The biogas can now be removed, purified and converted to energy z. B. be converted in the internal combustion engine. The residues must be out be discharged to the fermenter and serve because of their high quality for agriculture Inorganics mostly as fertilizer.

One Another basic differentiator is in what temperature range the Fermentation process held becomes. Here one differentiates in - Psychrophilic temperature level, that is called at ambient temperature or below and - mesophilic temperature level, this means at temperatures between 30 ° C-40 ° C and in - Thermophiles Temperature level, that is at temperatures above 50 ° C - maximum 57 ° C.

By the biological increase in activity Accompanying temperature increase are psychrophilic driven fermenters not useful. Most biogas plants are anaerobic Degradation today in the mesophilic range, only when using fatty Substrates the thermophilic range is selected. The most common at the moment operated biogas plant is a wet fermentation to conventional pumping and to use mixing aggregates which are continuous and mesophilic Area is driven.

Of the Main raw material in German biogas plants is usually beside Manure of the Silage maize. Other raw materials are various cereals, whole plant silage, Grass silage, oilseeds, Field crops, solid manure and other residues from the cattle and Pig breeding, poultry manure, but also crop residues like Beet leaves, potato herb, vegetables and charcoal leftovers. However, the different substrates differ in terms of their gas potentials, so that currently predominantly NaWaRo's with high Energy content used for biogas production. In general, everyone can biological raw materials with a methane-forming bacteria enough degradable organics are fermented to biogas.

The Biogas technology is currently subject to strong development processes. An attempt is made to improve the process stability of the plants, to increase the efficiency of anaerobic degradation and at the same time the available To make greater use of the energy of the substances used. Especially under pressure from the dramatically increased prices for commodities at frequent insufficient use of the thermal energy of the gas systems a significant increase in efficiency in the focus of the operators.

The Object of the present invention is for a with Biomass to be performed pre-treatment method to develop a device for mechanical digestion of the biomass, so that in a process carried out with this pretreatment method a faster anaerobic digestion process and increased gas yield can be achieved.

Under mechanical digestion is understood to mean the comminution of substances, by energy input the size, shape and structure of the feed is changed to smaller particle sizes. this leads to to improved process parameters or makes certain procedural steps only possible. It must adhesive forces like electrostatic forces, capillary forces, Solid-state bridges and even intermolecular forces or van der Waals forces in the molecular Area overcome become. Man overcomes these adhesive forces and reaches the desired Crushing effects due to impact, friction, and cutting or shearing stress the substance to be crushed.

In The process biomass is conditioned, especially mechanically prepared using biomass regrind. In the procedure will the biomass regrind as a starting substrate to a product substrate reconditioned, leaving it in a fermenter of a biogas plant to generate an increased Biogas quantity can be used.

During the mechanical treatment, a process liquid is supplied to the starting substrate (biomass regrind) which, depending on the type of biomass, promotes only the mechanical or the mechanical and a biochemical conditioning process, whereby a product sub strat formed during the subsequent fermentation process, with a comparable amount of starting substrate, allows the generation of an increased amount of biogas and simultaneously accelerates the production of biogas.

The process liquid contains biochemical ingredients, such as anaerobic vaccines bacterial strains and / or in the form of biochemically acting as catalysts enzymes.

there comes as an additive a recirculate from a fermentation process used, which already contains anaerobic bacterial strains and / or enzymes.

With The biomass regrind as a starting substrate is by mechanical Preparation and feeding of process fluid performed a forced wet grinding.

The belonging to the inventive device method consists essentially of a combination of vaccination and simultaneous (synchronous) mechanical preparation of the material to be ground. The process is referred to as "IMPF-PRALINE SYNCHRONOUS SUBSTITUTE PROCESSING".

The Task, a device for special mechanical conditioning indicate the biomass, according to claim 1 by a special hammer mill type for one Forced wet grinding, the so-called "IMPF-PRAL-MILL" in short "IMPRA-Mühle" solved. The "IMPRA mill" works after the Principle of an impact mill, However, has features that are essential from the conventional impact mills differ.

The invention will be described below with reference to 1 and 2 explained in more detail. In this context, the associated method is explained in more detail in the following tables, diagrams and formulas.

The Figures show:

1 an impact mill ["IMPRA mill"] in a schematic representation and

2 a screening part of a screen basket.

1 shows the impact mill 100 , which is used to carry out the method, on the basis of which the method is described in more detail.

One in a housing 102 rotating rotor 104 , driven by a motor (not shown), carries as grinding tools 106 in the rotor 104 swinging hanging hammers or rackets. Due to the resulting centrifugal force at the appropriate speed these are directed radially outward in operation, but can be difficult or not grindable Good 1 through the pendulous suspension 124 Dodge, which is an overload protection.

The regrind 1 becomes tangential over a shaft 110 into the grinding chamber 108 given and by the impact stress on the hammers 106 and hole edges of the sieve grate 112 (or sieves) crushed. The minced product will pass through the grinding circle 114 - first circle - attached grate 112 discharged, whereby the Siebart, the hole size and form or also Siebweite of the Siebrostes 112 the fineness of the final product determined sustainable.

The regrind 1 can not bypass the grinding chamber 108 leave the crushed regrind 1' must through the sieves or sieves used 112 escape.

Furthermore, peripheral speed, number and width of the hammers affect 106 , as well as the flow rate on the fineness of the product.

The IMPRA mill 100 is unique because in through a sieve basket 112 closed club circle or grinding circle 114 called, liquid 2 continuously through nozzles in a first area 118 (not shown in detail) with direction of action on the incoming regrind 1 . 1' is introduced.

At the same time, further nozzles in a second circle are in a second area 120 (not shown) for adding liquid on the back side of the screens outside the grinding circle 114 with direction of action on the sieve basket 112 appropriate.

All nozzles in the entire or at least partially first and / or second area 118 . 120 can for adding process fluid 2 or also for the addition of, as a rule, clear water or a cleaning liquid for cleaning purposes of the mill 100 be used with stationary and / or running machine.

The process is characterized in that the regrind 1 with simultaneous metered addition of a liquid 2 crushed while being vaccinated according to the ingredients of the liquid. The regrind 1 can not have a bypass or the like the grinding circle 114 leave, as long as not the seven used 112 appropriate fineness of the ground material 1' is reached.

As regrind 1 - Starting substrate - come all previously known in biogas plants Energieträ cereals, maize silage, grass silage, rye whole plant silage (GPS), manure from cattle, chickens, pigs, manure from pigs and cattle, vegetables, fruit, meat and offal, organic fats, oil crops, etc.

The following process parameters are during operation of the impact mill 100 to be observed. Process fluids are used 2 , which are also referred to as vaccine fluids in the presence of components dissolved therein.

As "vaccines" in the process fluid used 2 Anaerobic bacterial strains and / or enzymes are used which are either already contained in a process fluid of another process and are simply removed and used from these processes or those of the respective process fluid 2 be deliberately added as additives.

The range of process liquid used as a "seed liquid" ranges from clear water to support mechanical conditioning or to support mechanical and biochemical conditioning over water with "vaccines" as an additive to a process fluid 2 , which already has vaccines and is withdrawn as recirculate with a dry matter content (TS) of up to 10% from another process.

As the temperature range of the vaccine fluid 2 a temperature range of +5 to + 70 ° C is considered.

The ratio of the amount of regrind to proscess fluid addition (seed liquid) 2 in the grinding circle 114 is variable and is preferred depending on the millbase in a range of 60:40 [TS (not absolute, it is already liquid and is considered): liquid] as the largest TS concentration up to 10:90 [TS: liquid] than lowest TS concentration.

at the relationship Dry substance to process liquid addition (Vaccination liquid) the dry matter content of the seeding liquid is taken into account accordingly.

Resulting effects and advantages for the overall process in biogas plants are:
First: homogenization of the particle size of the dry substance for a better flow behavior of the mash, ie the pumpability increases with simultaneously decreasing pump pressures. Depending on raw materials, the throughput capacity of pumps has been increased by up to 80% or the energy consumption has been reduced proportionately. At the same time, wear of the equipment and piping used is reduced by up to 30%.

Secondly: Generation of many small particles. This is a higher wetting ability given the substrates, which reduces floating layers in the fermenter or dismantled. To have to therefore existing agitators in the fermenters are operated less (only temporarily) and / or need lower drive power, overall with energy savings up to 60% in total.

Third: Generating a larger specific surface at an optimal time at optimum temperature, around one to enable more effective biochemical metabolism of microorganisms. The biological activity is thus accelerated, which means an immediate gas production. It became dependent on raw materials Up to 38% difference in gas production already on the first day in favor the open-minded opposite unmilled and vaccinated biomass. Corresponding This results in lower residence times and can be a burden on the foul space clearly increased become. Proportionally, lower fermenter volumes result same power.

Fourth: increase the degree of digestion in favor of a disintegration of raw materials to the cellular or at the molecular level, whereby on the one hand the cell water dissolved Fabrics immediately for the microorganisms accessible are, on the other hand, the molecular structure destroyed, that individual fragments in solution can go and therefore also for the anaerobes become vulnerable. It is next to the mentioned secondary effect as a primary effect an absolute gas yield, ie raw material-dependent gas yield, up to 10% (in exceptional cases 12%).

in the the following part will be the applied tests or investigation methods presented in their theory, systematics and objectives.

Of Other materials, equipment and detection equipment described.

It is shown what results obtained with the investigations could be and which statements can be made with it in what way the individual examinations with each other keep in touch.

in the Connection will be the practical procedures and the results the experiments shown.

It is detailed on the used Zer smaller machines received. The "IMPRA mill" (hammer mill), which was mainly used for the mechanical crushing experiments, and also the Gruber mill used for comparative purposes in the particle size and viscosity studies are described.

The "IMPRA mill" of the NDK series used in all grinding trials 4 has a baffle zone 108 in the upper part of the grinding chamber with internal rotor 104 and an electric motor connected via a drive shaft, in this case a 75 KW three-phase motor (not shown).

The grinding chamber 108 has a diameter of 680 mm and a depth of about 400 mm.

In it runs the rotor block, on which symmetrically on 6 axes in each case 12 free-swinging clubs 106 are suspended, which stand in operation by the rotational speed perpendicular to the outside.

The intended drive speed is up to 3600 rpm in 60 Hz operation, whereby at maximum speed, a peripheral speed of the clubs 106 of over 125 m / s can be achieved.

In 50 Hz operation 3000 rpm are achieved, which corresponds to a peripheral speed of approx. 100 m / s. The lower part of the grinding chamber 108 is made of two interchangeable sieves 112 surrounded, through which the milled substrate is discharged, they have a sieve area of about 0.6 m ² . The tests used perforated metal sieves with hole diameters of 15 to 25 mm. 2 , Furthermore, various shapes of an expanded metal in different sizes can be specified.

The in a biogas plant previously installed and for comparison purposes used Grubermühle Type sample mill MM300 is similar a hammer mill built up, but does not achieve their crushing result Impact, but predominantly by cutting stress.

In the grinding chamber of Grubermaschine, which surrounded by a ring sieve is, rotate a knife cross and 4 lying close to the sieve with about 3000 rpm. The electric drive installed here Owns mill a power of 55 KW. The mill shreds due to the design dry, that is, there can be no additional Fluids during be added to the milling process.

The The following preliminary considerations serve the later understanding in the evaluation of the results.

Dry matter and organic dry matter

With the TS is the characteristic value of the dry residue defined according to the DIN standard meant, which is today generally more common, if after Norm wrong.

The Determination of TS serves to determine the content of substances and water in sample materials, such as in this case unrefined or Milled corn silage or mash for feeding the biogas plant. The TS is necessary as a reference if analytically determined results refer to the dry matter become.

Of Furthermore, TS is a fundamental parameter in biogas technology the substrates that are fed to the biogas plant, and has effects on many procedural parameters such as foul space load, supplied amount of substrate or flow behavior and mixability of the substrates.

For the determination of the TS, there is a standard, the DIN 38414 part 248th Basically, this is a sample over 24 hours or to constant weight in a drying oven at 105 ° C dried. TS is mostly given as a percentage. From the previously determined wet weight and the subsequent dry weight, the TS can now be determined according to the following formula:
Dry substance, in%
Mass of empty shell, in g
Mass of shell with sample material, in g
Mass of shell with dry matter, in g

The OTS or the loss on ignition is a measure of the salary on fleeting, organic compounds of a sample. It is the TS related Weight loss of a sample which is ashed at 550 ° C. The OTS will as the amount of organic material assumed to be biological can be reduced and is thus in the biogas technology the percentage Proportion of the substrate which utilizes the microorganisms can be. The oTS is used in biogas production as a reference for room load, Infeed freight and especially for the specific gas production of the substrate, such as the determination of biogas potential.

organische Trockensubstanz der Trockenmasse einer Probe in %
Masse des leeren Tiegels, in g
Masse des Tiegels mit der Trockenmasse, in g
Masse des Tiegels mit der geglühten Trockenmasse, in gThe determination of the OTS depends, as in the case of the TS, on DIN 38414 Part 3, in which case the sample is ashed for at least 60 minutes or until constant weight at 550 ° C. in the muffle furnace. The OTS is given as a percentage and is calculated as follows: formula 1

dry matter of dry matter of a sample in%
Mass of empty crucible, in g
Mass of crucible with dry matter, in g
Mass of the crucible with the annealed dry mass, in g

Particle size determination

The Objective of the particle size determination is to make an ordering distinction between the particles to be able to The particle size and its distribution, as well as the shape are useful features to the impact to determine the mechanical comminution. By determining this Parameters can in the further building up properties such as gas yield or viscosity on the basis of Particle sizes quantified become. For the particle size analysis Today, methods such as screening and sifting, sedimentation, optically digital counting method or surface measurements to disposal. Due to the substrate properties of NaWaRo's, sedimentation processes are not possible. Optical digital counting method and surface measurements would be very good measuring methods. The determination of particle size and shape by Screening and sighting is a tried and true method of investigation because of their easy handling and good result production for the investigations made here were selected. Was used a machine screening with a driven by an eccentric rotating Sieve set.

The Material to be analyzed is placed on a sieve. In the sieve set are about a Siebpfanne the sieves with increasing mesh size on top of each other set and completed by a lid. The sieves are after DIN 4188 standardized with regard to mesh size, wire gauge and tolerances. By the with the Siebrüttler generated movement of the material to be analyzed fall the smaller particles according to the mesh size through the sieves, the larger ones stay lie on the respective sieves. After a defined sieving time the individual particle masses are balanced on the respective sieve trays and for further Evaluation purposes.

ΔQ₃(x_i)

Summenanteil der Partikelgröße

M(x_i)

Masse des Partikelgrößen-Intervalls (von x_i-1 bis x_i), in g

M_Ges

Gesamtmasse der untersuchten Partikel, in g

The description of the particle size is made by specifying an equivalent diameter, in practice, the letter x _{i is} used for this purpose. The measurements of the individual particles result in a proportion that has a certain particle size fraction in the total proportion. This can be represented in a lookup table or graph as a particle size distribution. The sum of the mass in a particle size interval is ΔQ3, it is calculated from the mass fraction by the total mass. Index 3 indicates the mass reference here. Formula 2 Sum percentage ΔQ ₃

ΔQ ₃ (x _i )

Sum of particle size

M (x _i )

Mass of the particle size interval (from x _i-1 to x _i ), in g

M _Ges

Total mass of the investigated particles, in g

Q₃(x_i)

Summenverteilung der Partikelgröße

ΔQ₃(x_i)

Summenanteil der Partikelgröße

The totaling of the proportions ΔQ ₃ from the smallest to the respective particle size x _i gives the cumulative distribution Q ₃ (x _i ), resulting in values of 0 to 1, the proportions can thus be regarded as percentages. Formula 3 Sum Distribution Q ₃

Q ₃ (x _i )

Sum distribution of particle size

ΔQ ₃ (x _i )

Sum of particle size

q₃(x_{i, m})

Verteilungsdichte bezogen auf die mittlere Partikelgröße des Intervalls, in l/mm

ΔQ₃(x_i)

Summenanteil der Partikelgröße

Δx_i

Intervallbreite von x_i-1 bis x_i, in mm

Another characteristic is the distribution density, which is the proportion of the total quantity in a certain size interval with respect to the interval width. In terms of sieving, it is the mass fraction that remains between two sieves with mesh sizes x _i and x _i-1 . Formula 4 distribution density q ₃

q ₃ (x _{i, m} )

Distribution density based on the mean particle size of the interval, in l / mm

ΔQ ₃ (x _i )

Sum of particle size

Δx _i

Interval width from x _i-1 to x _i , in mm

In order to obtain a single characteristic for the distribution, it makes sense to introduce a "middle" value. Calculated and specified here is the x _50.3 value. This is the particle size where 50% is smaller and larger at the same time. Again, the index 3 refers to the mass. This value is either read from the Q ₃ -diagram or approximately calculated by linear interpolation from the acquired values. The values determined here were interpolated, assuming who this may mean that the Q ₃ curve in the range y = 0.5 approximately corresponds to one straight line.

z₅₀

Zerkleinerungsgrad bezogen auf den Wert x_50,3

x_50,A

charakterisierender Einzelwert x_50,3 des Aufgabegutes (Substrat), in mm

x_50,M

charakterisierender Einzelwert x_50,3 des Mahlgutes (Produkt), in mm

Based on the value x _{50.3, it is also} possible to calculate a degree of comminution which quantifies the comminution performance of the mill. Formula 5 Calculation of the degree of comminution

z ₅₀

Size reduction based on the value x _50.3

x _{50, A}

Characterizing single value x _{50.3 of} the material to be charged (substrate), in mm

x _{50, M}

Characterizing single value x _{50.3 of} the material to be ground (product), in mm

Of the Crushing degree is defined as a value that is greater than 1 is. The bigger the Value, the further towards smaller particle sizes has been crushed.

There in the analysis with sieve the measured particle size of a Diameter-equal sphere corresponds, however, the form of the crushed ones NaWaRo particles by no means takes a spherical shape, in addition still needs a fiber length determination carried out become. A thinner and long particles fall also by a close-meshed sieve, but does not necessarily correspond to the measured particle size.

For the fiber length determination were per sample 100 Particles measured. These particles were taken from the individual screen batches, that is in each case 20 Particles per screen residue, to obtain a more even distribution of the removed particles. Again, a characteristic value was formed in order to be able to make comparative statements. The value L _50.0 was introduced based on the particle size parameter x _50.3 . This value represents the fiber length at which 50% is longer and at the same time shorter than L _50.0 The index 0 here refers to the measurement of the particles by counting, so it can be read from a number distribution diagram or, as happened here, approximately by linear interpolation are determined.

For biological and chemical reactions, it is often useful to specify the specific surface area of the substrates. Since, however, can not be determined directly from the measurement results such, it is proposed based on a diagram according to push, shown in 3 to estimate the form factor φ.

It is assumed here of the particle form 1. The diameter a is assumed to be a calculated average particle size value x _50.3 , for the longer height b of the cylindrical particle the mean length L _{50.0 is} used.

S_V

spezifische Oberfläche (Oberfläche/Volumen), in 1/mm oder mm²/mm³

φ

Formfaktor, zu bestimmen aus Diagramm

q₃(x_i,m)

Verteilungsdichte bezogen auf die mittlere Partikelgröße des Intervalls, in 1/mm

Δx_i

Intervallbreite von x_i-1 bis x_i, in mm

x_i,m

mittlere Partikelgröße des Intervalls, in mm

The specific surface area can then be calculated from the volume density distribution as follows: Formula 6 Specific surface area calculation

S _V

specific surface area (surface / volume), in 1 / mm or mm ² / mm ³

φ

Form factor, to be determined from diagram

q ₃ (x _{i, m} )

Distribution density based on the mean particle size of the interval, in 1 / mm

Δx _i

Interval width from x _i-1 to x _i , in mm

x _{i, m}

mean particle size of the interval, in mm

The specific surface thus represents the existing surface per unit volume. If it is crushed, the chemically and biologically reactive increases area and it may be based on the mass or the volume of the chemical-biological Sales are increased per unit of time.

flow behavior

The flow behavior of substances strongly influences the properties in process engineering processes, the parameter used here is the determination of the viscosity. It is a measure of the viscosity of a fluid and can be measured as a resistance force through a generated shear rate. In biogas technology, this mainly affects the eligibility and intermixability of the substrates. Increasing viscosities of the mash often produce poor conveying capabilities, high pump pressures and high wear on machines used, it is also expected with increased energy input for promotion and mixing. For the measurement of the dynamic viscosity η there are many different methods today. For example, rotary viscometers, falling ball viscometers or capillary viscometers are frequently used, but these are usually limited in their possibilities to the measurement of liquids with Newtonian flow behavior without impurities. Experiments with self-made ball drop viscometers did not work as desired, and also the determination of the viscosity based on the pressure difference during the conveyance of the fluid through a tube failed. Therefore, for the following series of experiments due to Substrate properties a rotation viscometer used. The rotary viscometer normally operates with a rotary body and a cup in which the fluid to be measured is located.

The Geometry of these bodies is known and so can by the rotation of the cylinder, a resistance torque, which results from the generated shear rate, read on the meter and in a viscosity be converted. Because this principle, however, only for Newtonian liquids is thought and the cylinder-cup principle is not for the measurement of fluids with impurities and non-Newtonian flow behavior suitable, as required in the experiments, quickly showed that a modified procedure had to be developed and applied. It became a special stirrer made to replace the cylinder-cup system. This stirrer rotates in the sample with different, defined speeds and the generated Resistance torque can be read off the meter. The power the sample liquid against the stirring can as a result for the comparison measurements are used.

Gas yield determination

The Determination of gas yield, named after DIN Faulverhalten, provides information about the anaerobic degradation of organic substances. It serves the characterization of substrates and their fermentation ability, fermented in a biotechnological material conversion process become. in principle is a sample substrate in a standardized measuring apparatus under defined fermented anaerobic conditions and through the produced and collected biogas a statement about the fermentation ability met. This experiment shows what differences a pretreatment of substrates with regard to their degradability by microorganisms.

Of the Try becomes detailed described in DIN 38414 Part 8 and VDI 4630 and the procedures Measuring equipment and calculations are based on these guidelines.

The produced gas quantity was determined with Eudiometerrohren.

For the experimental approaches were Samples are examined before and after crushing to build on it a statement regarding the improvement of biogas yield by mechanical and / or biochemical digestion.

V_i,N,

Gasvolumen im Normzustand, in ml

V

gebildetes Gasvolumen, in ml

p_L

Luftdruck zum Zeitpunkt des Ablesens, in mbar

p_W

Dampfdruck des Wassers bei der Temperatur des umgebenden Raumes, in mbar

T₀

Normtemperatur, T₀ = 273 K

p₀

Normdruck, p₀ = 1013 mbar

T

Temperatur des Gases bzw. des umgebenden Raumes, in K

Since the weighed substrate sample quantities turned out to be relatively small, but large gas yield fluctuations were to be expected due to the partially highly inhomogeneous sample material, all investigations were carried out in triplicate and then averaged. In order to calculate the amount of gas generated by the added seed sludge, a blank sample with the seed material was prepared in each case. As material for this purpose, as proposed in DIN 38414 Part 8, a digested sewage sludge from the municipal sewage treatment plant used, here digested sludge from the digester before the separation of the sewage treatment plant. This digested sludge had a residence time of about 30 days in the digester and was then bottled. According to sewage treatment plant information, it has 2% -2.2% dry matter, the measured pH of the sewage sludge was 7.4. In order to obtain a normalized result, it is necessary to convert the detected gas quantities into a standard volume according to the following formula: Formula 7 Calculation of the standard volume

V _{i, N,}

Gas volume in the standard state, in ml

V

formed gas volume, in ml

p _L

Air pressure at the time of reading, in mbar

p _W

Vapor pressure of the water at the temperature of the surrounding space, in mbar

T ₀

Standard temperature, T ₀ = 273 K

p ₀

Standard pressure, p ₀ = 1013 mbar

T

Temperature of the gas or the surrounding space, in K

V_S

spezifisches gebildetes Gasvolumen während der Versuchszeit bezogen auf ein Gramm oTs, in ml/g

ΣV_n

gebildetes Netto-Gasvolumen für die betrachtete Versuchsdauer, in ml

m

eingewogene Masse des zu untersuchenden Substrates, in g

TS

Trockensubstanz, in

oTS

organische Trockensubstanz, in

This standard volume can now be converted into a specific gas production value, whereby the produced gas quantity is related to one gram of the initial weight: Formula 8 specific gas production

V _S

specific volume of gas formed during the experimental period based on one gram of oTs, in ml / g

ΣV _n

Calculated net gas volume for the considered test duration, in ml

m

weighed mass of the substrate to be examined, in g

TS

Dry matter, in

oTS

organic dry matter, in

The calculated results of the recorded specific gas production were plotted on a graph in cumulative form over the duration of the experiment. At the curves let statements about improving the fermentation ability of the meet investigated substrates. Furthermore, it is possible to calculate the total cumulated production of biogas Determine if the degree of degradation of the substrate by appropriate pre-treatments can be increased.

Evaluation and further description the device and the method

The following evaluation is based on Tables 1 to 12 and in addition to those already described 1 and 2 by means of 3 to 10 ,

The 3 to 10 demonstrate:

3 Diagram for the determination of the form factor φ and the sphericity ψ _Wa for three regular particle shapes according to Stieß,

4 Q ₃ sum distribution of raw and ground corn silage with different screen perforations,

5 q ₃ distribution density of raw and ground maize silage with different screen perforations,

6 L ₀ sum distribution of raw and ground corn silage with different screen perforations,

7 Summarized results of the viscosity measurements of the different mash samples,

8th Series II - Cumulative gas yield in the standard volume of raw and ground maize silage over time,

9 Gas yield of the vaccine sludge without and with enzyme and

10 Trial III - Cumulative gas yield in the standard volume of raw and ground maize silage with and without enzyme addition over time.

When Sample material or starting substrate was used for the investigations Corn silage used. This corn silage is equivalent to today maize silage found on farms. she is already during harvesting with a maize shredder pre-crushed and then on a Silohaufen has been compacted by an acidification process to obtain a preservation.

at the evaluations of the comminution effects by the mechanical Digestion was tested on samples taken during an experimental phase of the "IMPRA mill". The processed maize silage comes from the silos of a Biogas plant and was bought by surrounding farmers. Of In addition, a sample of the same raw substrate was used as a comparison ground with the Grubermühle to disposal, which was previously used on the biogas plant. The sampling happened directly before the grinding or directly afterwards. The different Samples were based on the experimental parameters during the mill trial. For the Experiments to determine the biogas yield has been twice a larger amount Milled corn silage of a farmer under his own opinion. The samples obtained from raw and ground corn silage were hermetically sealed for subsequent examinations.

at the determination of TS and oTS was carried out as previously described.

each Sample was tested in triplicate for its TS and oTS to be a statistical To obtain mean value. For the TS determination was used for aluminum trays which became the oTS determination performed with ceramic crucibles. For the Investigations included drying cabinets and a muffle furnace Available. The results were for the investigations roughly the following values shown in Table 1.

The values determined by the OTS correspond to the literature values, too The TS content of raw corn silage is a common value, which is high dispersion here at the type of silage storage, or the location of sampling in Silohaufen. The strongly fluctuating TS levels of the ground samples are different Experimental parameters in the trial of the "IMPRA mill" to explain because with different Water additions during the grinding was experimented.

For the particle size determination, a dry sieving was chosen as the investigation method, since the substrates to be investigated, however, some had a high water content, the samples had to be dried first. As a result, it was found that the liquid in the sample was liable to stick due to fines from grinding during drying. To remove these substances, the samples were first washed in a 0.09 mm sieve and then dried at room temperature and room humidity. The resulting cake could then be sieved after careful working apart of the Restverklebungen. Raw maize silage and grinding samples from the biogas plant were examined after grinding with different sieve openings of the "IMPRA mill" and a sample of the formerly installed Gruber mill.

The Sieving time was set to 4 min, the sieve system works according to the rotation eccentric principle and had a deflection of 15 mm. A sieve set was used consisting of grid wire sieves of hole widths 4 mm-2 mm-1 mm-0.5 mm - bottom. The residues on the individual sieve trays were balanced and documented and based on the calculations described above carried out.

For visualization, a calculation of the averaged Q ₃ sum distributions and the q ₃ distribution densities of experiments with different sieve hole sizes is used here.

Furthermore, it can be seen that the reduction of the screen perforation during grinding also causes a shift of the Q ₃ curve towards smaller particles. Thus, the proportion of particles below 2 mm when using a 25 mm sieve is about 42%, when using a 20 mm sieve at about 60% and the proportion when using the 15 mm sieve at about 70%, where the starting material here only has a share of about 12%. The Grubermühle with its grinding result is comparable to the use of the 25 mm sieve of the "IMPRA mill", but slightly shifted towards smaller particles, so the further the Q ₃ curve is shifted in the direction of smaller particles, the stronger the comminution effect of the The same sieve analyzes bring as distribution density the following diagram, shown in 5 , forth.

The q ₃ curve of 5 describes the frequency of the proportions of the examined material in a certain size interval. The integral below the curve from the smallest to the largest particle, here from 0 to 10, therefore again gives the total amount 1 or 100%. It can be seen here that the raw corn silage has no maximum particle size, it indicates a relatively uniform occurrence of all particle sizes between 1.5-8 mm. The corn silage ground with the "IMPRA mill" shows its maximum frequency at all grinding between 0.75-1 mm, whereby the density here from the largest to the smallest sieve perforation of approx. 0.3 over approx. 0.35 up to approx Gruber mill grinding has the maximum frequency at approx. 1.5 mm, which is almost twice the particle size of the average grinding, in its further course the q ₃ curve of the Gruber mill is identical to that of the "IMPRA" Mill "when using a 25 mm sieve to compare.

Also in the q ₃ distribution density, therefore, the clear comminution effect can be seen. The further the maximum of the curve or the main surface under the curve is shifted in the direction of smaller particles, the greater the degree of comminution that has been achieved. In this example, this is best achieved by milling through the "IMPRA mill" with a 15 mm sieve60, where the majority of the particles are in a range of about 0-3 mm It is proposed to calculate the mean value x 50,3, which can be read in the diagram of the Q ₃ sum distribution at the ordinate value 0.5, or calculated approximately by linear interpolation The different results of the investigations were averaged and reported the following values shown in Table 2.

The Table 2 shows the average values x 50.3 for raw and ground Corn silage. You can see a clear decrease in the mean Particle size x 50.3 by using the grinding technique. So has the raw corn silage an average particle size of 5.22 mm, the use of grinding with a 25 sieve comminutes the Particles already more than half and with a 15 sieve, the particle size is almost quartered. The Grubermühle reached here a similar one Value like the "IMPRA mill" when using the Twenty-five sieves, they roughly halve the mean particle size related on the starting material.

Basically but here to mention that for the Investigations of the Grubermühle only one sample available stood while the results from the grinding of many averaged values originated, that is made mistakes during the sampling or grinding, z. B. by different starting material effecting positive or negative results, the influence Results of the investigations of the Grubermühle statistically much stronger.

A parameter quantifying the grinding result is the degree of comminution. The degree of comminution can be read as the factor by how much the starting material has been comminuted. This value based on the mean particle size of the substrate and product shows in the mills and different grinding, the results shown in Table 3.

The sole consideration of the particle sizes on the basis of a sieving not useful, because the substrate properties high fibrous fractions have. To characterize these was additionally a manual fiber length determination carried out.

For fiber length determination 100 particles were measured per sample to be examined. These Particles were taken from the individual sieve batches, that is in each case 20 particles per screen residue, the more even distribution get the removed particles. The measuring took place by Hand and was divided into four classes: 0-1 cm, 1-3 cm, 3-5 cm and> 5 cm.

The 6 shows in a diagram the L0 sum distribution of raw and ground corn silage with different screen perforations. As with the particle size, an L0 sum distribution is used here for the evaluation, but this is not based on mass but, as the index 0 indicates, on the number. The values of the individual investigations associated with the perforations were averaged for this purpose.

The diagram 6 shows the percentage of fiber lengths applied versus fiber length in centimeters. The maximum fiber length is assumed to be 10 cm. Even if only 100 particles were measured here, a trend of fiber shortening by grinding technology can be shown.

The Shifting the L0 curves towards shorter fibers with decreasing Screen perforation is evident here as well as in the particle size analysis. However, this becomes even clearer at the x 50.3 equivalent Value L50,0 in the table 4 shown in the Annex, the averaged L50,0 values of raw and ground corn silage.

By the mechanical digestion is the mean fiber length of 0.87 cm when using a 25er sieve by more than half Shortened 0.37 cm. The use of smaller screen perforations further reduces the fiber length, However, this effect is not as strong to prove as in the Particle size, so it sinks the mean fiber length of 0.37 cm at the 25er sieve 0.35 cm at the 20er sieve to 0.31 cm when using the 15er sieve. The substrate digestion with the help of the "IMPRA mill" thus achieves a significant shortening of the fiber length questionable The result here is the Grubermühle because of their fiber length lies at 1.01 cm above the average fiber length of the raw corn silage 0.87 cm. For one thing, one must assume here that the starting material but very different and from the Grubermühle only a single sample available and on the other hand the Grubermühle seems to have a particle shredding to achieve, however, shortened they do not use the fiber lengths.

The specific surface SV relevant for biological and chemical reactions can now be calculated with the aid of the obtained parameters x 50,3 and L 50,0, by using this a form factor from the diagram of 3 is determined. The individual determinations here show that the value for all samples is between approx. 1 and 5, the corresponding form factors φ are then derived from the diagram of the 3 to 1.2 to 1.4. For safety's sake, the form factor here is assumed to be 1.4 for all calculations. With the formula 6, the results are the following values listed in Table 5, the specific surface areas SV, of the various grinding operations.

The Raw material raw corn silage, has a specific determined surface from 2.66. With 10.23, the grinding with a 15 sieve reaches the biggest specific Surface, this corresponds to 3.8 times the starting material. With 3.1 times and 2.6 times the surface area the untreated maize silage are the grinding with the 20s or 25er sieve clearly behind the result of the 15er sieve. The worst result produced the Gruber mill with compared to only 2.3 times of the raw substrate and a specific surface area of 6.06.

By the previous washing of the samples in a 0.09 mm sieve fell all particles below size 0.09 mm away and were not included in the measurement.

Nevertheless would No particles of this size huge Influence the measurement or the result only slightly correct below. Because of this systematic error in all screenings occurred, the samples are comparable with each other. Not all Bonding and matting to be resolved before screening In the screenings, agglomeration often occurred on the 4 mm and the 2 mm sieve. These agglomerates sat down Corn silage made of glued fine particles with fibers together. This fact has a, albeit small, impact on the particle size distribution, which shifts in the direction of smaller particles.

For fibrous fabrics, as examined here, the fibers may be very long, but due to the small diameter, they will fall through the screens of the smaller particle sizes. So you have to be the fiber length be seek to make a statement about the particle size distribution. A measurement of 100 fiber lengths per sample indicates only a certain trend for samples as here taken, but can not be considered 100% representative because it would require a larger number of measured particles. However, the trend of the results is clearly visible and also fits the results of the respective screening.

For the viscosity measurements mash samples from the biogas plant were examined, these distinguished on the one hand in their Vermahlungsart, that is, use of different Sieblochung, as well as in their TS content.

Around a comparison of the grinding technique with another crusher was added here another sample of a Gruber mill used. This was installed before the trial of the "IMPRA mill".

When Reference samples for estimation the viscosity was water and salad oil with known viscosities measured. For the investigation became the described agitator with the rotational viscometer used. The stirrer was placed in the sample bottle with the mash sample and placed on the Attached to a rotational viscometer. In order to obtain a uniform measurement result, Shake the sample beforehand preferably mixed well. The stirrer turned now in the mash and the generated resistance torque could on the meter be read. The speeds were graded at 10-50-100-200-300-400-500-600 rpm set per minute. In practice, it quickly became apparent that the Mash does not provide constant resistance torques, so that each speed drove for half a minute and this is the maximum value was determined.

from that resulted in a "worst case measurement", which is the maximum Resistance torque at selected Reveals speed. To get a reproducible result, Each measurement was performed three times and the results averaged. The temperature of the samples was kept the same to one possible Influence of this on the viscosity to keep low.

The 7 shows in a diagram significant differences in the viscosity of the mash samples depending on the grinding method and TS. The highest resistance to stirring is provided by the Gruber mill milled samples, the higher TS also increases the viscosity here, although the difference of the TS is only 0.8%. With about half and less of the resistance produced, mash samples ground with the "IMPRA Mill" had a much lower viscosity, and among these samples, the samples ground with the 15 sieve showed lower viscosity than the 20-sieve mills despite higher TS Considering the samples milled with the 20 sieve, a reduction of the TS by about 1.5% results in a reduction of the viscosity by a third, during the measurements a certain "felting effect" of the Gruber mill sample could be determined for a long time Fibers wrapped around the stirrer. This did not occur in the samples of grinding with the "IMPRA mill".

Out No quantitative viscosity value can be calculated from the measured values become.

however can for qualitative assessment the respective curves the impact mills their chart patterns with the diagrams of water and salad oil be contacted or compared. Water becomes here with a value η = 1 mPa and salad oil with a value of η = 100 mPa s assumed.

to Determination of the gas potential of raw and ground maize silage three different test series were carried out.

Of the first experimental approach in test series I dealt with the samples, the while the testing of the "IMPRA mill" the effects of differently used strainers during the Grinding with regard to the resulting gas yield of the individual samples examined.

test series II examined the raw substrate and mill samples of the material which raw available was placed, was spent for grinding and there with a 15er sieve was ground in the "IMPRA mill". From this should be a statement about the different gas yield of unmilled and ground Corn silage are taken.

The third series of experiments III, like series II, once again the different gas yields of raw and ground corn silage and additionally clarify whether when using anaerobic bacterial strains in the process fluid a further increase in biogas yield can be achieved.

The Investigations of the test series I regarding the gas potential showed no clear trend regarding the different ones Vermahlungsmethoden.

It the test series II was carried out.

Around to exclude the suspected error potential in the previous experiment I, was a series of experiments II fundamentally redesigned, the raw corn silage was now from a Silohaufen provided directly for grinding under its own Assessment spent, then directly afterwards the next day to make the Gärtestansätze to be able to. The Starting material was taken from the middle of a silo, to rule out mold processes and oxygen effects. Was continued only raw corn silage and ground with a 15er sieve substrate examined. The gas potential investigation was in each case three times carried out around to do justice to averaged values of statistics. The piecing the fermentation tests happened as described.

The Starting material was recirculated in the experimental series II Vaccine sludge spiked. The recirculated seed sludge contains all necessary bacterial strains for the anaerobic Fermentation.

Of the For example, seed sludge comes from a digestion tower sewage plant and is used in fermentation trials prescribed according to DIN 38414 Part 8.

The Production of the gauzes - starting substrate - took place after determination of TS and oTS of the two substrate samples, by one appropriate mixing of the individual shares.

The Data is shown in Table 6 below. The table 6 shows the determined percentage TS and oTS contents of the used Starting substrates.

The Table 7 shows the determined percentage TS and oTS contents the starting substrates used the test series II.

After preparing and mixing the samples, the pH was determined, which was between 7.0-7.2 for all samples. Adjusting the pH environment was therefore no longer necessary. After attaching and zeroing the Eudiometerrohre the gas yield determination of the test series II was started. Over a trial period of nearly 63 days, the produced gas volumes were documented and converted into the standard volume, averaged and cumulated over time. This results in the 8th illustrated diagram. The diagram of 8th shows the cumulative gas yield in the standard volume of raw and ground maize silage over time from the experimental series II After a lag phase of about 12 hours, the anaerobic degradation process begins with increasing gas production. The samples show a very steep curve in the first 6 days, after which the curve of the gas production gradually flattens until it shows almost no further growth from the 24th day on and thus develops an almost horizontal line.

Clearly To recognize is a strong drifting apart of the curves of the milled and raw substrate, the gas production of the grinding sample runs clearly steeper and the pretreatment affects the outcome both in terms of the total gas production as well as the production speed positive.

This is even more apparent in the following Table 8, in which percentage differences between each other as well as the total production the test series II are applied. After about 3 days is already 50% of the total gas yield has been produced, with the milled Sample reaches the 50% mark a little faster than the raw material. To 13 days already reached the degradation process of the milled corn silage 90% of total gas production while the unmilled sample produced here only 85%. With 97% after 24 days later, the rehearsals become similar again. From At this time, another gas production is only over one long period with very small increases.

The benefit of the mechanical digestion and thus the increase in gas yield is summarized in the column "Difference from raw material to sample" in Table 8 and 9 to see.

Here will be the percentage difference of gas production of different Substrates illuminated to each other. An initial delay of the ground Substrate after 5 hours compared to the raw substrate gives way quickly a difference of almost 38% after one day in favor of the mechanically-open-minded Sample. From this point on approaching However, the gas yield of the raw material is constantly the result of the treated Sample, and then after about 13 days, about 13% less biogas and finally about 9% less biogas than the open-minded, this means to produce ground corn silage. The examination period chosen for a very long time of 60 days was used to study the influence of residence time on the biogas production, where as described be determined could that the dismantling process already after approx. 30 days the overwhelming Has converted part of the usable organics to biogas.

The fluctuations in biogas yields can be explained by the effects of temperature and air pressure. Although these are eliminated, a small error remains due to measurement inaccuracies and different rapid temperature transitions from the environment to the gas collection room. After the test series II, the pH of the individual samples was again determined, which had set between 7.3-7.5. Inhibition due to the PH value is therefore not expected.

Building on the investigation described above became a series of experiments III performed. Again, raw corn silage was used as the starting substrate.

The Sampling took place directly before and after the hammer mill, the again with a 15er sieve was equipped. The samples were subsequently analyzed for gas potential spent to avoid substrate conversion processes.

through 16 Eudiometerrohren it was possible, four different test approaches à three Single samples with regard to increasing the gas yield by mechanical To examine digestion.

The Weighing and mixing the starting substrate with the inoculant - process fluid - sat as shown in Table 9, together.

The Sample material according to table 9 in test series III following percentage TS and oTS contents. The to be examined Samples in Run Series III consisted of those shown in Table 10 Substrateinwaagen.

The measured pH values of the individual samples were again in a range of 7.1-7.3, which meant that no further adjustment of the milieu was necessary. After the subsequent Setting up and zeroing the Eudiometer tubes was the gas yield study the test series III started.

In turn the produced gas quantity of the single samples was over one Trial period of 31 days documented.

The Results of the respective triple sampling were summarized and averaged.

These were then cumulated and in the standard volume based on one gram of OTS in the diagram of 10 applied over the experimental period.

The diagram in 10 shows from the third series of experiments III, the cumulative gas yield in the standard volume of raw and ground corn silage over time.

Also in test series III, a slight lag phase is apparent within from the first day, only then gas production increases sharply this being the case with the ground, that is mechanically, preconditioning Samples are much clearer, than the samples of the non-preconditioning raw substrate.

The curves in the diagram 10 show a very steep curve in the first 4 days, but this is slowly flattening. Overall, this flattening of the curves is more pronounced in the milled samples than in the raw silage, which does not cause so much kinking of gas production.

To By the 28th day, gas production continues to decline then slowly approach a horizontal curve. From At this time, none of the experiences of Experimental Series II notable gas volume increases to record.

The Table 11 shows the accumulated gas yields of the individual samples once in numbers and their percentage of total return.

The Experiments of the test series III were terminated after 31 days, since in test series II showed that from this point only small amounts of gas are generated, which is nothing worth mentioning to the total yield contribute.

By the test series III could in all sample bottles a pH between 7.4-7.5 an inhibition of the degradation process due to the pH value can thus be largely excluded.

Summary

Based the particle size studies can be shown that the use of a suitable mechanical digestion method, such as here the "IMPRA mill" the starting substrate clearly can shred. So will be the cheapest Case the proportion of particles smaller than 4 mm from 25% in the raw substrate on over 90% increased in the product substrate. It could be determined that the grinding result is highly dependent is of the sieve perforation of the passage sieves, so increases The proportion of particles smaller than 2 mm in the "IMPRA mill" of about 40% at the largest used Sieve to about 70% for the sieve with the smallest hole size.

The Gruber mill used as a comparison, in spite of its ultimately higher efficiency by means of cutting comminution, only achieves a comminution performance which corresponds approximately to the "IMPRA mill" with inserted 25 mm sieve in these tests lower efficiency in terms of single grind reduction better for the production of smaller particles in NaWaRos.

One Another advantage of the impact stress, based on the particle size measurement is tangible, is the stronger Disintegration of the substrate by more extensive force in the Crushing process, which does not occur in a cutting crushing. This allows Cells burst and destroyed which releases cell water and dissolved components become.

Also based on the obtained parameters such as Average and crushing levels can be positive effects for the process moor a biogas plant. The calculated mean x 50.3 shows that the particle size through the shredding technique used here is reduced fourfold, which the degree of comminution as characteristic of a mill with a value of 3.8 when using the 15er sieve in the "IMPRA mill" also confirmed Fiber length determination shows one of the particle size measurement analogous result on. Become through the crushing process with the hammer mill the fiber length more than halved, however, can be the use of smaller sieves here only small further decreases produce. The length of the Fibers are therefore not necessarily influenced by the screen perforation, but rather by the generated impact stress. underpinning this point will be additional through the result of the Grubermühle, which had a fiber value that was longer than the starting material.

The Crushing of the Gruber mill comminuted Visco-elastic material like NaWaRos contrary to every guess worse than the impact load of the IMPRA mill.

Of Furthermore, the results of the Grubermühle are based on a single sampling, while the Results of the "IMPRA mill" often averaged Represent values. However, if one starts from the results of the "IMPRA mill", which is a relative have a small fluctuation range, one can see the results of the Gruber mill refer to comparisons here.

Based the particle size measurement and fiber length determination the specific surface can be calculated further. These is the highest relevant for all biochemical transformation processes and reactions in the anaerobic Degradation, as a better ligand proximity and reaction surface is produced. The investigation results show that with the "IMPRA mill" when using the 15s sieves the best results are achieved, here is the specific surface almost quadrupled. Larger screen perforations to lead to a lower surface enlargement, because the particles and fibers are not crushed that far.

The Gruber mill produced only 2.3 times the surface area of the starting material and is thus behind the results of the "IMPRA mill" with 25er sieve insert, although the pattern mill smaller Particles produced, which basically to an increase in the surface to lead should.

This Effect has its reason in bad fiber length shortening this Mill, because the fiber length is a factor in the calculation of the specific surface one.

It can be seen that the fiber length shortening a has a significant effect on the increase in specific surface area. The cutting shredder used here ver likes the particles though to crush, however, the fibers are not shortened, they are apparently only scraped off and pressed through the ring sieve. The fibers are too elastic and the distance between the cutting edges of the knife in the Grubermühle is too big, than that shortens them can be. This leaves conclude that it is to improve the chemical and biological Attack by the microorganisms not only on the particle size reduction, but also on fiber shortening arrives, assuming that an increased specific surface area faster and better degree of degradation achieved With regard to this conclusion Thus, an impact load such as the "IMPRA mill" is more effective than a cutting crushing the Grubermühle and thus as a crusher for the substrate digestion in Biogas plants to be preferred.

An analogous result shows the viscosity measurement. Milling with the "IMPRA mill" halves the viscosities at about the same TS The use of smaller screen perforations lowers the viscosity a little further, but not proportionally to the decrease in particle size, which in turn indicates that the fiber length is crucial For the viscosity of the mash, which can certainly be explained by the entangling effect of longer fibers, this was also found in the experiments, since fibers were wrapped around the stirrer during the examination of the samples of the Gruber mill, which was evident in the samples of the "IMPRA Mill "did not happen. The measurements of the viscosity show that a higher mechanical degree of digestion such as the "IMPRA mill" greatly reduces the viscosity.The comminution of the particles and especially the shortening of the fibers significantly increase the flowability of the mash, a catching and cross-linking of the particles in the fluid In practice, this has a positive effect on the mixing and pumpability of the mash re flow capabilities are expected with lower power inputs. According to the BGA operator, the pump pressures of substrate conveyance could be more than halved by using the "IMPRA mill." In addition, conveyor and pump units can be operated more gently, which means less wear and hence longer service life and maintenance intervals. In order to reduce the viscosities and the associated improvement of the process parameters, a shortening of the fiber length should therefore be achieved with mechanical digestion of fermentation substrates in biogas plants. In this case, the impact load of the "IMPRA mill" has proven to be more effective.

The Measurements of the gas potential of raw and mechanically comminuted Maize silage occurred in three series of experiments: the first series of experiments I examined 7 different samples from different grinding. However, this initially resulted no trend-showing result. However, a discussion of the results left several problems and solutions become recognizable. A reason for the dubious result lies in the sample material, which is different Raw material came from and with it the samples among themselves too differently were.

These influences Now it was necessary to switch off in test series II. The samples came now from a starting material, were not until the investigation stored and the individual samples were each triplicate sampled to to get a statistically safer result. As a result can Now be noted that the gas potentials of the sampled raw and milled corn silage differ significantly.

For one thing, you can see now, see 9 and Table 8, that the anaerobic degradation process and thus the gas production is greatly accelerated by mechanical pulping, ground corn silage produces already after 10 days, the amount of biogas, which is produced by the raw corn silage after about 20 days.

To the Others have a gas yield which increases after 20 days to about 10% and after a residence time of 60 days to 8.9%. Furthermore It can be concluded that the quantities of gas produced in the Raw substrate samples strong and mechanically comminuted samples differ very little. The scatter is measured by the milling process significantly reduced, it occurs a homogenization of the substrate which results in lower fluctuations in the biogas process and positively influenced this.

In of the experimental series II could be proved that a mechanical Digestion, here the example of the substrate shredding with the "IMPRA mill", it the microorganisms possible makes, the organics of NaWaRo's faster and further digestion and conversion into biogas. In the raw substrate trapped nutrients are released by impact crushing and cell or plant structures so far destroyed, that the anaerobes make the organic components more accessible become. For the operation of a BGA with one currently becoming more common Dwell time of 20 days in the main fermenter, this means an increase in yield of 10%.

It a biogas production could be achieved in this series of experiments, the mechanical treatment of corn silage 86%, according to Buswell theoretically potential Income of 726 m.l./g. Raw corn silage achieved here only about 79% of the possible Biogas.

The third test series III was again based on the test series II performed, again fresh starting material was ground and then on investigated its gas potential. Here was again the different Gas yield from untreated to mechanically digested substrate checked and proven.

Use of enzymes

Further can be used in the process fluid and as an additive, enzymes which can bring about a disruption of the substrate. Of the enzymatic digestion is in substrate treatment in biogas processes a procedure, which through integration in the IMPRASYN process an improved function promises.

Under enzymatic digestion is understood to mean the conversion of a substance Initial subsidies towards a desired product through a chemical reaction catalyzed by an enzyme. For a variety of There are the corresponding reactions Enzymes which z. B. catalyze hydrolytic cleavage reactions, Break down proteins by hydrolysis or polymerization reactions cause. It is possible to use enzymes in process engineering to produce starting substrates to disintegrate at the molecular level or new ones for the process to receive useful products.

An enzyme is generally a protein that catalyzes a specific chemical reaction. This catalysis works by lowering the activation energy, which results in a faster achievement of chemical equilibrium. The resulting in the substrate conversion products are then available before and also the enzyme is then present as any catalyst in its initial form, freely available for further reactions. Originally, nature uses these proteins in cells to accelerate or facilitate chemical turnover intra- or extracellularly.

today can However, enzymes are produced biotechnologically targeted and thus also targeted for specific reactions are used. The economy of enzymes has only recently arrived, since enzymes are now industrially and can be manufactured industrially. They are now often in medical technology, food and paper industry used.

Exemplary mode of action of enzymes38. An enzymatically catalyzed reaction proceeds according to the following scheme: Enzyme + substrate ↔ enzyme-substrate complex ↔ product + enzyme

For the reaction On the one hand, the basic factors are spatial proximity in order to be catalyzed On the other hand, the ligands must be bound and immobile. Enzymes are specific, meaning they can only catalyze a particular reaction, further the activity of a Enzyme depends on numerous physical and chemical factors. Fundamental affect the temperature, the pH and the presence of denaturing Agents the effect of biocatalysts.

Of the enzymatic digestion is subject to the following intention. The in the Biogas production used fermentation substrates are composed in the NaWaRo area to a high percentage Lignocellulose, a supporting and scaffolding-forming Material which is composed of cellulose, hemicellulose and lignin. You can estimate in a ratio of 4: 3: 3 are accepted. Celluloses are long-chain polysaccharides consisting of coupled monosaccharides, the glucose building blocks. Hemicelluloses are heteropolysaccharides that are not just glucose building blocks included, but in addition a number of other sugars such as xylose, mannose, and galactose Arabinose. The degree of polymerization of hemicellulose (about 200) is significantly lower than that of cellulose (about 6000-16000) and is usually in a branched structure. Lignin is a three-dimensional crosslinked, aromatic hydrocarbon compound consisting of a number of monomeric building blocks by different, heavy degradable bonds are linked together. Lignin serves as Glue between the cellulose and hemicellulose and gives the lignocelluloskeletal structure of the plant the stability. The cellulose, hemicellulose and lignin may be from the microorganisms but not or only with difficulty be broken up and recycled and Thus, the energy content of NaWaRos can not be fully exploited. Through the use of special on the cleavage reaction of celluloses adapted enzymes it is possible to split the polysaccharides into oligo- or monosaccharides.

These Oligo- and monosaccharides are then in contrast to the polysaccharides mostly water-soluble and utilizable by the microorganisms.

Of the stored in the cellulose energy content is thus exposed and the anaerobes for their metabolism and thus made available for methane production. Furthermore, there are monomeric sugars, partly in a framework of lignin and cellulose included before. These are caused by the enzyme use additionally accessible for the Microorganisms. Coupling the mechanical digestion with the Enzymatic, so here are advantages: The mechanically comminuted Substrate have a greatly enlarged specific after their digestion Surface, making it for the enzymes is much easier to reach their ligands. The spatial Close, one fundamental factor for the function of enzymes, is improved, so that then the chemical Reaction can be initiated. A coupled digestion could thus significantly increase the effective energy yield of NaWaRos.

The following Enzymes are exemplary for the enzymatic digestion of NaWaRos can be used. Basically, the selected Enzymes will be able to contain the three building blocks of lignocellulose their for to break down the microorganisms into usable subunits.

In The paper industry has opted for lignocellulosic digestion primarily cellulases, hemicellulases and ligninases proven. cellulases in principle, cleave the 1-4-β-glycosidic bond the cellulose. This consists of glucose building blocks that are linked by the β- (1-4) -glycosidic Binding linked together are. After the reaction then lie individual glucose molecules or shortened Cellulose chains, which can be further decomposed enzymatically. specially In this reaction, the 1-4-β-glucanases are used, they to lead the hydrolysis of the cellulose.

Hemicellulases comprise a larger group of enzymes because the composition of hemicellulose consists of different monosaccharides. The basic structure of the polysaccharide consists predominantly of glycosidically linked glucose, xylose or mannose units, but in addition to the main chain further sugar residues such as galactose or arabinose are linked. In order to be able to split the main chain into the individual sugar molecules, the enzymes are mainly used 1-4-β-glucanase, 1,4-β-D-xylanase and 1,4-β-D-mannanase. These enzymes hydrolyze the glycosidic bonds of the heteropolysaccharide hemicellulose to produce the monomeric sugar molecules that can be utilized by the microorganisms. The ligninases are responsible for lignin degradation. Here, enzymes such as phenol oxidases, laccase and lignin peroxidases are used; they split the different bonds into the individual building blocks of the multi-branched lignin molecule. The biologically difficult to use lignin can thus be made partially degradable, but the main task of the enzyme is here the dissolution of the lignin crosslinking of cellulose and hemicellulose.

By using the IMPRASYN method, the substrate is crushed and all the way to the cellular Structure unlocked. It will make the specific surface strong elevated and nutrients the microorganisms and the enzymes made directly accessible.

from that results in a much higher Gas yield, per amount of starting substrate used, an increase in Biogas quantity per time, thus the residence time of the product substrates / fermentation substrates becomes considerably shortened in the fermenters. It is almost complete Dismantling, for the microorganisms of usable organic material.

With Firstly, the IMPRASYN procedure is used to vaccinate a "syn" chronological on of the substrate while of the digestion process, the "baffle" comminution, with the existing bacterial strains achieved from the biogas process and secondly, is a faster beginning anaerobic degradation process after incorporation of the substrate into the fermenter and thus also a faster methane production possible. Third, a homogeneous Mixing of the substrate with the bacterial strains during the Scraping process achieved.

Economically offers the use of the IMPRASYN method, if already installed Facilities significantly improved utilization of fermenter volumes and thus more gas with the same digging room and for new plants, the same performance, with significantly less investment in container construction.

Finally secondary effects of the IMPRASYN process in a biogas plant, namely, smaller ones and homogeneous particle sizes of the substrate for one better wetting with liquid. Floating layer formations are minimized because the substrate particles fall. In addition, a strong reduction of the viscosities of the Substrates, which further process features such. Lower pump pressures with concomitant energy savings, shorter stirring intervals with the same mixing and less wear in the Overall process are recorded.

m The result will even be gas and floating layers in the repository minimized, thereby facilitating aspiration and spreading to fields becomes.

With The process is an optimization of the entire process flow in biogas plants through a sustainable improvement of many process parameters reached. The profitability Existing plants will be increased and new plants will be cheaper.

1

Biomass Grist [Starting substrate]

1'

crushed Biomass regrind [product substrate]

2

process liquid [Seed liquid]

100

Impact mill [IMPRA - mill]

102

casing

104

rotor

106

Hammer / Bat

108

grinding chamber

110

shaft

112

Screening / grate / screen basket

114

grinding circuit

116

substructure

118

first Area [nozzle area]

120

second Area [nozzle area

124

commuting suspension

glossary

• Degradation: decomposition of chemical compounds in simpler molecules
• Degradability: property of a substance, due to certain reactions to be converted
• Anaerobic bacteria: bacteria of the anaerobic degradation process
• Biogas: Gas mixture of the main components CH ₄ and CO ₂ , formed by anaerobic degradation of organic matter; also called sewage gas, marsh gas or biogas; usable by combustion in gas engines for energy production
• Biogas plant: Plant for the production and utilization of biogas
• biocenosis: Cohabitation of different organisms, here means the symbiosis acetogenic and methanogenic bacteria of anaerobic digestion
• Throughput: processed / enforced amount per unit of time
• Renewable Energies: (Renewable Energies) Energy sources that infinitely long available stand and renew themselves, in contrast to the fossil fuels, the to limited stock of materials are bound
• Faulraumbelastung: Indicator for the mass supplied to kg oTS per m ³ _fermenter and day
• Fermentation: fermentation process in a biogas plant, in which under anaerobic conditions the organic material is reduced
• Fermenter: container, in which the biological conversion of the substrates takes place; also Reactor, fermentation tank, digester
• Hemicelluloses: group of polysaccharides different Composition found in plant fibers and cell walls of grasses, cereals and others higher Plants occurs, v. a. together with cellulose and lignin in the Wood-cell wall
• HPLC: High Performance Liquid Chromatography or English high performance liquid chromatography HPLC is a liquid chromatography method, with which one separates substances and identify and quantify them can
• Vaccine substrate: also seed sludge, material used in the fermentation tests, which comes from a digester of a sewage treatment plant and already subjected to the digestion process
• Cogeneration: Energy generation or conversion process in which simultaneously provided mechanical or electrical and thermal energy becomes
• lag phase: means a start-up or even lag phase in which the bacteria start with the anaerobic digestion process
• Ligands: A biochemistry term for a molecule that binds to a target molecule can, here refers to the complex formation between enzyme and to splitting molecule
• Lignin: highly polymeric plant substance found in woody plants fills the cell membrane spaces (lignification or woodiness) and support structures how cellulose connects to each other
• Mash: prepared mixture of substrate, manure, turbid water and additives, before being transported to the fermenter becomes
• Renewable resources: material or energy used, agricultural and forestry products
• Organic dry substance: fraction of the organic matter of a Substance without water content, i. d. R. by drying at 105 ° C and then annealing at 550 ° C determined also loss on ignition
• Degree of polymerization: the number of macromolecular Chain united basic building blocks
• Primary energy: Energy in its original, technically not yet developed or converted form
• Silage: preserved by lactic acid fermentation plant compounds
• Substrate: general name for the used for fermentation organic material from which biogas is produced
• Dry substance: anhydrous proportion of a substance after the Drying at 105 ° C, According to DIN standard actually dry residue
• Murky Waters: recirculated process water after separation of non-fermentable components, includes a lot the bacterial strains for the anaerobic degradation process
• Residence time: time span in which the substrate supplied in the fermenter lingers
• worst-case measurement: detecting the worst result of a Measurement

Abbreviations

• BGA

  biogas plant

  H ₄

  methane

  CO ₂

  carbon dioxide

  EEG

  Law for priority renewable energies (Renewable Energy Act)

  EU

  European Union

  CFC

  Hydrofluorocarbons

  H ₂

  hydrogen

  HPLC

  High Performance Liquid Chromatography

  i. N.

  in standard condition

  CHP

  Cogeneration

  NaWaRo

  renewable resource

  oTS

  organic dry matter

  TS

  dry matter

Claims (7)

Impinging mill with a housing and a sieve basket receiving a biomass regrind as a starting substrate, in which rotating grinding / crushing tools, fixed in a variable speed rotor for conditioning the starting substrate to a product substrate, in particular for mechanical processing, are arranged, characterized in that a closed sieve basket ( 112 ) with a filling shaft ( 110 ), which has a grinding chamber ( 108 ) with a starting substrate ( 1 ) (Biomass formulation), force-conditioning grinding circle ( 114 ), wherein the product substrate ( 1' ) only by passing the strainer basket ( 112 ) the grinding chamber ( 108 ) leaves and the grinding chamber ( 108 ) during forced conditioning from inside or inside and outside process fluid ( 2 ) can be fed. Impact mill ( 100 ) according to claim 1, characterized in that the process fluid ( 2 ) via a first nozzle area ( 118 ) into the interior of the grinding chamber ( 108 ) and a second nozzle area ( 120 ) from the outside to the grinding chamber ( 108 ) can be brought. Impact mill ( 100 ) according to claim 1, characterized in that the impact mill ( 100 ) for the mechanical preparation of the starting substrate ( 1 ) by an impact crushing about an axis relative to the statically arranged screen basket ( 112 ro grinding tools, in particular impact hammers or impact beaters ( 106 ), which according to the peripheral speed (rotor speed and rotor diameter) a decisive success of the comminution between 75 and 145 m / sec. guarantee. An impact mill according to claim 3, characterized in that for setting the desired substrate particle size of the product substrate ( 1' ) the peripheral speed, the number of impact hammers or bats ( 106 ), as well as the throughput of the starting substrate ( 1 ) is changeable. Impact mill ( 100 ) according to claim 1, characterized in that for setting the desired substrate particle size and the product substrate ( 1' ) (Biomass recipe) differently shaped openings in the strainer basket ( 112 ) are provided by exchangeable screens or grates with predetermined opening areas. Impact mill ( 100 ) according to claim 1, characterized in that for setting the desired substrate particle size and the product substrate ( 1' ) a circular screen perforations of the screen basket ( 112 ) of 15 to 25 mm can be specified, however, but also different shapes of an expanded metal of different sizes can be specified. Impact mill ( 100 ) according to claim 2, characterized in that the first and second nozzle areas ( 118 . 120 ) also serves to supply cleaning fluid, so that at least one of the nozzle areas ( 118 . 120 ) for cleaning purposes with stationary and / or running impact mill ( 100 ) can be used.