DE19721979C1 - Biogas reactor assembly for small-scale agricultural use - Google Patents

Abstract

A biogas generation assembly consists of a cylindrical reactor (5) which is sub-divided (2, 3) in a cruciform pattern, has end-walls (1) and rests on bearings (6, 7), by which it can be rotated and inverted as required, mixing the contents. The reactor (5) has pipe inlets (8, 9, 10) and outlets with rotating couplings for the introduction of raw material and discharge of residues, and an overhead (1, 4) gas outlet pipe. The cruciform sub-dividing walls (2, 3) guide the fermenting mass in a U-shaped route through the reactor, minimising the incidence of route short cuts and facilitating the transfer of heat from the fermented mass to fresh mass. A corresponding biogas production process, involving fermentation at 10-70 deg C in a closed vessel which can be rotated through 180 deg , is also claimed.

Description

introduction

The invention relates to a method according to the preamble of An saying 1 and a device according to the preamble of claim 2.

It is known that by anaerobic fermentation of organic residues flammable biogas can be generated. The resulting biogas can e.g. B. used in combined heat and power plants for combined power and heat generation will. This environmentally friendly process for regenerative energy gain has been spreading slowly lately. Even in public biogas technology is very popular. Especially in the field of agriculture very large amounts of organic residues fall into the biogas plants high quality, almost odorless fertilizer and processed into biogas could.

This enormous biogas potential from agriculture falls considerably Chen share in small agricultural holdings with livestock between between 30 and 150 LU (large livestock units).

However, the technology of the previous biogas plants is very strong on Großan were aligned, because the rule applies: "The larger a biogas plant, the more economical. "

For the small, mostly very interested in agricultural biogas technology Chen companies currently only have the following options for the benefit to be able to use biogas fermentation processes:

a) Do-it-yourself construction of a biogas plant using used parts Some drawbacks

• - Investment grants from the federal government, states, etc. a. mostly omitted.
• - Enormous expenditure of time necessary with low hourly wages.
• - No guarantee for self-made system from used parts.
• - Tax assessment and depreciation of such investments is difficult.
• - The system looks technically and optically like an "old" system.

b) addition of co-fermentation substances to increase the biogas yield Some drawbacks

• - Long-term contracts with suppliers must be concluded.
• - Impurities often have to be sorted out by hand.
• - Perfect hygiene must be guaranteed.
• - Problems can arise with the approval of the system.
• - A farm can become a business.
• - The investment costs of the biogas plant are higher.

c) Several small businesses decide to create a community facility Some drawbacks

• - Higher transport costs to the biogas plant there and back.
• - Higher administrative and organizational effort.
• - The use of the centrally generated thermal energy is more difficult.
• - Rules must be found for the parties' disputes.
• - The planning and implementation of such a project takes longer.

In summary it can be said that there are already possibilities with who also ferment the organic residues from small farmers economic operations can be made economically.

However, there is always more effort for the individual farmer

• - on own labor
• - in organizational and administrative activities
• - in financial means

necessary.

This patent application is intended to try the basic technology to simplify the biogas plants so that, in particular, smaller farmers economic investments can become profitable. To achieve this, esp special of the basic idea that fermentation plants large and immobile liche "real estate" are to be sold.

Fundamentals of the biogas process

The production of biogas from agricultural manure with the help of a bio operate gas system, anaerobic microorganisms is relatively simple, while z. B. in the case of fermentable bio-waste, a previous treatment such as e.g. B. crushing and mashing with water or sorting of contaminants for fermentation is necessary.

In order to be able to produce biogas from a material that has been prepared for fermentation, there are some minimum requirements for the environmental conditions in the fermentation tank:

• - There must be anaerobic conditions.
• - The temperature must be as constant as possible at a value in the range of 10 can be kept up to 70 ° C. There are two optimal temperature ranges for a maximum biogas yield at approx. 35 ° C (mesophilic fermentation) and at approx. 55 ° C (thermophilic fermentation), which normally heats up the manure necessary.  
• - There must be a minimum dwell time of the slurry in the fermentation tank the.
• - A possibly emerging floating layer, which prevents the biogas from escaping on the slurry surface must be destroyed.
• - There must be a balanced nutrient composition in the or ganic input, such as this. B. with liquid manure, grass or bio waste len is the case.
• - There may be no or only small amounts of contaminants that affect the fermentation process can inhibit, be present in the input.

State of the art

The state of the art can be found in the following plants, among others:

• 1. Schulz, Heinz; 1996; Biogas practice; Cape. 3. Plant technology; Eco book Publishing house, Staufen near Freiburg
• 2. Wellinger, A .; 2nd ed. 1991; Biogas manual; Cape. 3. Plant technology Verlag Wirz AG, Aarau
• 3. Board of Trustees for Technology and Construction in Agriculture KTBL (ed.); 1993; Costs of agricultural biogas production; KTBL working paper 185; KTBL font sales at Landwirtschaftsverlag GmbH, Münster-Hil trup

In [3./S. 32] shows a frequently used biogas flow system. This system essentially consists of a horizontal, zylin Dry fermentation tank with heating, gas extraction dome, slurry connections and Agitator is equipped.

This is the technique

• 1. The manufacture of the agitator is very complex.
• 2. The installation or storage of the agitator in the container (often longer than 10 m) is very complex.
• 3. For different container types and dimensions must also under different agitators are built.
• 4. Since the agitators are usually driven from the outside, the loading must can be specially sealed at the point where the shaft passes through the Container wall (danger of a leak!).  
• 5. Installations in the container (e.g. for heating) cannot be freely positioned will. It must always be ensured that there are no collisions with the agitator arise.
• 6. The agitator shaft located in the container is very difficult to ge be waiting. This is the complete emptying and cleaning of the Container required.
• 7. The quality of the mixing strongly depends on the agitator design, the speed and the duration of stirring.
• 8. Since there are "moving parts" in the tank, there is a risk of de fectes with subsequent, expensive repair increased.
• 9. Repairs z. B. on the agitator require complete emptying and cleaning the container. The subsequent recommissioning can due to the slow doubling times of the biogas bacteria Take months.
• 10. It should be avoided that newly fed substrate by unfavorable Flow conditions flow directly to the overflow (short circuit flow) and thereby reducing the biogas yield. This can be achieved through a longest possible route between inflow and outflow. In the system shown however, the supplied substrate flows in a direct way, i.e. H. without any order steering from inflow to outflow.
• 11. The heating in the system shown is very complex as part of the Agitator shown, d. H. the heating pipes are on the agitator shaft attached and rotate with it.
• 12. If there are sink layers in the tank that are not above the above Can be removed, the entire container must be emptied and how which are put into operation again.
• 13. It is hardly possible to have different environments within the container conditions (e.g. different temperatures in the inlet and in the overflow range) that could lead to process optimization. Experiments of this kind are not possible with the existing technology.
• 14. By a high-speed agitator is a principally undesirable me mechanical stress (shear) of the biogas bacteria present, leading to can lead to a lower gas yield. A slow running agitator on the other hand, must either be constructed very elaborately or for a very long time work to achieve sufficient mixing. The containers mixing with an agitator can therefore not be optimally designed the.  
• 15. The floating layer is cut by the agitator shown the consequence that the biogas can escape unhindered. At that very slowly rotating agitator can cut the parts of the floating layer continue to swim up and dry out over time. A fermentation these parts are then no longer possible. But especially in the swimming layer substances are contained, which lead to a high biogas yield can, there is an unused biogas po when using this method potential through the emerging, non-fermented floating substances.
• 16. Standardization of these flow systems is only possible to a very limited extent Lich, because the very complex for the different container dimensions Agitator must be readjusted again and again.
• 17. In the container is for other internals such. B. the procedure and thus the biogas yield could improve, there is no space because the stirring Factory-poor, roam almost every place in the container.

Task of the invention

The main task of the invention was a biogas fermenter to create the is as simple, robust, low-maintenance and inexpensive to manufacture as possible.

Furthermore, attempts were made to develop the fermenter in such a way that it

• - Enables a higher biogas yield.
• - is easy to standardize.
• - If possible, has no moving parts inside the container.
• - The lowest possible energy consumption during manufacture and operation required.
• - Due to its simplicity, self-construction by farmers is permitted.
• - avoids or at least minimizes the disadvantages mentioned above.
• - also the profitability of smaller agricultural biogas plants enables.

Solution of the task

This task is essentially accomplished by a method and a device solved with the features of claims 1 and 2.  

Advantages of the invention Cost advantages

• 1. The fermenter consists only of extremely simple and easily standardized Components.
• 2. When storing the fermenter on heavy duty rollers, it is possible that fermentation containers with different dimensions (length, diameter) standard be stored on the same rollers.
• 3. The heavy duty casters used in the device can be used as standard parts are bought. Suppliers are e.g. B. Wache, heavy duty castors, Hamburg. Heavy duty casters are also used in other areas of the facility construction such as B. in cement production or waste incineration in Rotary kilns are required and are therefore easy to obtain.
• 4. The invention also includes a proposal with the complete on Heavy duty casters can be dispensed with. With this solution can extremely ko be built in a way that saves costs.
• 5. With the solution without heavy duty casters, no moving ones at all Parts (no storage points) required in the entire fermenter.
• 6. The maintenance and repair work is negligible.
• 7. The "upside down" of the container can possibly be done by hand, na of course with the appropriate translation. To have to essentially only friction and flow losses in the container inside can be overcome. If a built-in agitator the content should mix, it must, for. B. be in operation for 1/2 hour. The high expenditure of time then no longer allows manual drive. With the manual drive you can saving biogas plants operating at the economic limit. At the same time, the systems are more flexible and do not require any electrical energy more during operation.
• 8. All connections for substrate supply, substrate removal and biogas extraction can be realized with exactly the same hoses and swivel joints, so that the advantages of standardization can also be used here.
• 9. Since the built-in partitions and mixing walls make the container excellent bilize, this can be built easier and cheaper. As a material glass fiber reinforced plastics (GRP) could be ideal.

Process advantages

• 1. Due to the simpler, cheaper design, it is rather possible with two or several containers that are connected in series or in parallel. This means that larger quantities of substrate can also be processed. In particular  The use of a series connection is a multi-stage bio gas system with higher biogas yield conceivable (development potential).
• 2. Through the partition in the tank, the slurry path from the inlet to Overflow almost doubled. This creates the risk of short circuit currents gen reduced with the result that either higher biogas yields reali Siert or alternatively, relatively short containers, possibly with larger ones Diameters can be used.
• 3. The mixing of the container contents is much gentler and ef more effective than when using agitators. An increase in biogas Prey is therefore possible because methane bacteria have a very negative effect on mechanical React to stress.
• 4. The only slight noise pollution during daily z. B. 1/2-hour stir Ren of the agitator tank can be greatly shortened with the new device will.
• 5. In the case of severe sink layer problems, the container can be rotated so that the partition is horizontal. In the upper half of the container Then deposit the sediment layer on the partition. There is now the possibility speed, the upper half of the tank with part of the sink layer over one Subtract substrate connection. The container can then be used again and again be loaded with fresh substrate. The biogas yield is in this The process may sink, but not completely collapse, as is the case with the complete emptying of the agitator tank to remove the sediment layer would be the case.
• 6. Since the connections for the substrate supply (low temperature) and Substrate removal (fermentation temperature) can be positioned directly next to each other a heat exchanger can be easily installed.
• 7. The built-in partitions and mixing walls can serve as a heating surface. There the heat can be supplied directly inside the container. Warmth this reduces losses. In the case of agitator tanks, heat is required exchangers can be attached to the tank wall, as they do not stir work may be taken. The heat supply leads to the container wall however to higher heat losses.
• 8. Between the fully fermented substrate directly in front of the substrate outlet opening and the freshly fed substrate can automatically through the partition a heat exchange (partial heat recovery) take place. There de warming up the freshly fed substrate to fermentation temperature very much consumes a lot of energy, there is an energy saving effect here.

Brief description of the drawings Fig. 1: schematic diagram of the fermenter

• - The drawing shows the lying on four rollers ( 6 ), closed, closed, cylindrical fermenter ( 5 ) with connections in a greatly simplified representation.
• - In the fermenter there are two mutually perpendicular walls, which are referred to as a mixing wall ( 3 ) and partition ( 2 ).
• - The horizontally arranged mixing wall cries four openings.
• - The vertical partition has no openings. It goes in the Ge not to the mixing wall over the entire length of the container.
• - If it is necessary to mix the fermenter contents, the whole Fermenter rotated through 180 °. In a subsequent mixing process, the Direction of rotation changed and the process repeated.
• - To enable the rotary movement of the fermenter without dismantling the connections for substrate supply and removal, as well as for biogas withdrawal, who uses the flexible hoses ( 8 , 9 , 10 ).
• - The fermented substrate can flow freely from the container over the substrate overflow ( 9 ) so that the container is not under pressure.
• - Due to the changing position of the fermenter, two biogas connections are required tig. Only the top connection is active because the biogas is in the fermenter rises to the top.

Fig. 2: How the fermenter works

In addition to the basic sketch of the fermenter, this drawing shows

• - The resulting in the fermenter and through the active (upper) biogasane finally emerging biogas.
• - The level of the substrate in the container and in the hoses.
• - the slight inclination of the entire container. This is intended to release the biogas facilitate.
• - The tether that prevents the fermenter from slipping in the axial direction that should.
• - The swivel connections, which the rolling movement of the fermenter without Disassembly of the connecting hoses should allow.

Fig. 3: Mixing process in the fermenter

• - The drawing shows how the partition and the mixing wall work are responsible for the substrate guidance and mixing in the fermenter.
• - The 180 ° rotation of the fermenter is shown in five steps.

Fig. 4: Structure of the fermenter

• - The drawing shows a perspective view of the structure of the Fer menters with partition and mixing wall (= essential content of patent applications dung).
• - The upper, right quarter of the cylindrical fermenter cut away and the front Front face completely omitted.

Fig. 5: Simplified storage of the fermenter

• - The use of heavy duty rollers for storing the fermenter can become a significant cost factor due to its high fill weight. As Alternatively, direct storage on the floor is shown here.
• - Around the fermenter on the floor alternately in position 1 and position Being able to roll 2 becomes six obvious solutions in this drawing proposals made with either a force F or a torque M work.

Fig. 6: Combination of several fermenters

• - For multi-stage processes or for larger substrate throughputs, meh More fermenters can be connected in series or in parallel.
• - The drawing shows an example of two fermenters connected in series.
• - The simultaneous rolling of several fermenters on the floor can be prinzi in the same way as with a single fermenter. The drawing shows two additional variants, which only apply to several, e.g. B. in series ge switched fermenters is conceivable.

Fig. 1-6: Reference list

1

Biogas withdrawal opening (active)

2nd

partition wall

3rd

Mixing wall

4th

Biogas withdrawal opening

5

container

6

Heavy duty roll

7

foundation

8th

Substrate supply (hose)

9

Substrate overflow (hose)

10th

Biogas extraction (2 × hose)

11

Swivel

12th

Hose bracket

13

check valve

14

Substrate feed pump

15

Tether

Claims (10)

1. A process for the production of biogas in an airtight container through mixed and evenly charged with fresh fermentation substrate at a temperature between 10 ° C and 70 ° C, characterized in that the destruction of the floating layer or the mixing of the organic material takes place so that the container content is rotated by 180 ° and then the floating layer now below is automatically mixed with the overlying sink layer. 2. Device for the production of biogas, consisting of a closed, mixable, cylindrical, lying container with Connections sen for the supply and removal of the organic material to be processed and for the removal of the resulting biogas, characterized in that the container with changing Direction of rotation can be rotated by 180 ° about its longitudinal axis and that there is a partition wall ( 2 ) in the container, which is arranged vertically and is somewhat shorter than the container, the partition wall being arranged flush on a container end face and on this container end face on one side of the partition of the connection for the sub stratzufuhr and on the other side of the connection for the substrate overflow, so that the substrate is U-shaped through the container and a short-circuit flow is prevented, and being on the opposite side of the container at least two connections for the biogasau controversy, at least one of which is at the top before and after rotating the container by 180 °. 3. Apparatus according to claim 2, characterized in that in the container one or more preferably at half height horizontally arranged mixing wall ( 3 ) with one or more openings be found, the openings advantageously in the middle of the resulting through the partition wall halves are positioned. 4. The device according to claim 2, characterized in that the connections to the container (substrate supply, substrate overflow, Biogasent acquisition) via flexible hoses ( 8 , 9 , 10 ) and swivel joints ( 11 ), so that the container without dismantling the connections with alternating direction of rotation can be rotated by 180 °. 5. The device according to claim 2, characterized in that the entire container is rotatably mounted on four rollers and completely around Can be turned 180 °. 6. The device according to claim 2, characterized in that the cylindrical container lies directly on the floor and can be unrolled can achieve a rotation of 180 °. 7. Device according to one of claims 2 or 3, characterized in that the partitions and mixing walls also serve as heating surfaces. 8. The device according to claim 2, characterized in that the cylindrical container by special choice of materials or by its Design also acts as insulation. 9. The device according to claim 2, featured through a heat exchanger through which ent in the fermented substrate heat energy the freshly supplied substrate is preheated. 10. Device according to one of the preceding claims, characterized in that two or more units are connected in parallel and / or in series.