DE102007029748A1 - Plant for the production of biogas, comprises a fermenter into which a nutrient medium is introduced and is fermented to produce biogas, a pressure sensor, which detects the pressure of the biogas in the fermenter, and a control device - Google Patents

Abstract

The plant for the production of biogas, comprises a fermenter (2) into which a nutrient medium is introduced and is fermented to produce biogas, a pressure sensor (20), which detects the pressure of the biogas present in the fermenter, a control device, which generates a signal controlling the filling quantity of the nutrient medium present in the fermenter, and a heat exchanger through which process heat required for the fermentation is introduced to the nutrient medium. A sensor signal of the pressure sensor is transmitted to a control device. The plant for the production of biogas, comprises a fermenter (2) into which a nutrient medium is introduced and is fermented to produce biogas, a pressure sensor (20), which detects the pressure of the biogas present in the fermenter, a control device, which generates a signal controlling the filling quantity of the nutrient medium present in the fermenter, and a heat exchanger through which process heat required for the fermentation is introduced to the nutrient medium. A sensor signal of the pressure sensor is transmitted to a control device, which compares the actual pressure of the biogas with a rated pressure that is predetermined. The signal adjusts the supply of the nutrient medium to the fermenter and/or discharges the medium from the fermenter. The predetermined rated pressure is equal to the atmospheric pressure. The control device regulates a storage device (10) for the nutrient medium, the influx of the nutrient medium by regulating valves and/or charging pumps (31, 32) and outflow of the nutrient medium present in the fermenter by controlling valves. The fermenter has exit points for entirely or partially fermented nutrient medium present in the fermenter. The exit points are opened and closed through the controlling valves of the controlling device. The storage device upstream to the fermenter has a mixing unit in which the nutrient medium to be introduced to the fermenter and a gaseous medium are mixable and the mixture is introduced in to the fermenter. The mixing unit has a first inlet over which the nutrient medium is introduced into the mixing unit, a second inlet over which the gaseous medium is introduced into the mixing unit, and a third inlet over which the nutrient medium taken from the fermenter is introduced to the mixing unit. The biogas plant has a gas pipeline through which the biogas obtained from a gas storage area of the fermenter is introduced to the second inlet of the mixing unit. A gas compressor and/or a gas pump (13) is connected upstream to the second inlet of the mixing unit. An independent claim is included for a procedure for pressure regulation of a biogas plant with a fermenter.

Description

The The invention relates to a biogas plant with a fermenter, in the a nutrient medium can be introduced, through the fermentation biogas is generated, and a method for pressure control of such a biogas plant.

One Such fermenter and a biogas plant using this fermenter are known. In the fermentation of the nutrient medium in the fermenter biogas is produced, which is located in a gas storage area of the fermenter accumulates. As a result, an overpressure is built up in the fermenter, which entails that the known biogas plant be designed pressure-proof got to. Such a biogas plant must therefore be approved by the authorities and regularly checked by experts. this leads to disadvantageously not only to high production costs, but also to high operating and maintenance costs.

It Now object of the present invention is a biogas plant of the aforementioned type and a method for pressure control of a such biogas plant in such a way that a simplified Manufacture and / or lower operating and maintenance costs of Biogas plant can be achieved.

These Task is solved by the biogas plant according to the invention in that the biogas plant has a pressure sensor, by which the pressure of the fermenter biogas is detectable that a sensor signal the pressure sensor is passed to a control device, which the actual pressure of the biogas with a predetermined or predefinable Target pressure compares, and that the control device at least a the filling quantity of the nutrient medium in the fermenter regulating Signal generated by which the supply and / or the discharge of nutrient medium in or out of the fermenter is adjustable.

The inventive method hits solution the above-mentioned object that by a gas sensor, the pressure of the biogas contained in the fermenter and a gas sensor generated sensor signal is passed to a control device, and that by the control device, the amount of the located in the fermenter nutrient medium is regulated such that the control device from the pressure sensor recorded actual pressure of the biogas with a predetermined or predetermined target pressure compares, and that at too low a pressure of the fermenter located biogas increases the supply of nutrient medium and / or the removal of the nutrient medium reduced from the fermenter and at too high a pressure of biogas the supply of nutrient medium decreases and / or the removal of nutrient medium from the fermenter elevated becomes.

By the measures according to the invention will in an advantageous manner in the invention, both for the mezophilic as well as the thermophilic area suitable biogas plant achieved by the regulated supply and / or removal of nutrient medium into or out of the fermenter the pressure of the fermenter, by fermentation of the nutrient medium produced biogas adjustable and thus below a certain pressure value, especially under atmospheric pressure, is durable. As a result, the reliability of the biogas plant according to the invention elevated. By the regulation of the charge in the fermenter is on the one hand the available in biogas standing gas storage area reduced or enlarged and Thus, the pressure prevailing in the fermenter gas pressure increased or reduced. Furthermore, the amount of the fermentation produced biogas proportional to the amount of in the fermenter nutrient medium, so that by regulating the amount of the nutrient medium in an advantageous manner, a regulation of the pressure of the biogas allows becomes. The control device evaluating the sensor signal of the pressure sensor Regulates advantageously the function of the supply and / or removal of the nutrient medium causing components of the biogas plant, so that in an advantageous Way a fully automatic operation of the same is made possible.

A advantageous development of the invention provides that the pressure below the atmospheric Pressure is maintained. This has the advantage that thereby the fermenter and thus the biogas plant can be particularly simple.

A Further advantageous development of the invention provides that the control device is a feed device for the nutrient medium and / or the inflow of the nutrient medium regulates regulating valves and / or at least one feed pump. This measure has the advantage that this in a particularly simple manner the supply of the nutrient medium is adjustable to the fermenter.

A Further advantageous development of the invention provides that the control device controls the outflow of nutrient medium in the fermenter Venti le regulates. In this way, in a simple way and Way a downstream control of the located in the fermenter nutrient medium allows.

A further advantageous embodiment of the invention provides that the supply of the nutrient medium to the fermenter causing feeding device comprises a mixing device through which ver the nutrient medium with a gaseous medium miscible and the mixture thus formed is fed into the fermenter. Such a measure has the advantage that as a result an improved mixing of the nutrient medium in the fermenter can be achieved, so that an improved fermentation of the nutrient medium can be achieved, which leads to an increased gas generation rate.

A Further advantageous development of the invention provides that that for mixing the nutrient medium used gaseous Medium is the biogas produced in the fermenter. Such a measure has the advantage of a particularly cost-effective operation.

A Further advantageous development of the invention provides that removed from the fermenter, wholly or partially fermented broth passed to the mixing device, there with the fed into the fermenter broth and the gaseous Mixed medium and in turn fed into the fermenter. Such an approach has the advantage that thereby a circulating of the fermenter allows which is an improved fermentation and thus increased gas production causes.

Further advantageous developments of the invention are the subject of the dependent claims.

Further Details and advantages of the invention are the embodiment can be seen that will be explained below with reference to the single figure. It shows:

1 a schematic representation of a biogas plant

In 1 is now a general with 1 designated biogas plant, which is a fermenter 2 having, via a feed line 3 that in the fermenter 2 to be fermented nutrient medium M can be fed. The fermentation of the nutrient medium biogas B is generated, which is located in a gas storage area 2a of the fermenter 2 accumulates and via a gas exhaust pipe 4 from the fermenter 2 is dissipatable by valves 5a respectively. 5b is opened or closed accordingly. That from the fermenter 2 discharged biogas B is either - as here - via a gas line 4a a consumer 6 fed or fed into an external gas line system. Such a biogas plant 1 is known and therefore need not be explained further.

The accumulation of the obtained by the fermentation of the nutrient medium M biogas B in the gas storage area 2a of the fermenter 2 causes an overpressure to build up as a result. As a result, the fermenters used so far 2 and thus the biogas plant 1 had to be sufficiently pressure-resistant to meet the legal requirements, for example, the German pressure vessel regulation, to meet. In addition, the known fermenter must 2 usually approved by the authorities and checked regularly by experts.

The described biogas plant 1 it now allows the pressure in the fermenter 2 below a certain pressure level, for example below the atmospheric pressure, by providing that by a corresponding regulation of the filling quantity F of the nutrient medium M by a change in the supply of the nutrient medium M and / or the removal of one already in the fermenter 2 located, completely or partially fermented nutrient medium M in the fermenter 2 prevailing total pressure below a predetermined or predefinable pressure value, preferably under a bar. For this purpose, by means of a gas pressure sensor 20 the pressure of the fermenter 2 generated biogas B detected continuously, quasi-continuously or at certain discrete points in time and that of the gas pressure sensor 20 generated sensor signal of a control device 30 is supplied. For the sake of clarity, in 1 the to the control device 30 current and outgoing signal lines not shown. The control device 30 compares that from the pressure sensor 20 detected actual pressure of the biogas B with a predetermined or predetermined target pressure. Is now the pressure of the biogas B in the line 4 and thus in the fermenter 2 too high, the supply of the nutrient medium M is reduced and / or it is the nutrient medium M 'from the fermenter increased 2 via discharge lines 8a . 8b . 8c dissipated. This will increase the volume of the fermenter 2 located nutrient medium M, M 'and thereby reduces the production of biogas B by fermentation of the nutrient medium and the biogas B available gas storage area 2a increases, resulting in a lowering of the gas pressure in the fermenter 2 results.

Is the gas pressure in the fermenter 2 - For example, due to too high a removal of biogas B - too low, the fermenter 2 amplified fed nutrient medium M and / or to a lesser extent nutrient medium M 'from the fermenter 2 taken so that the gas production increases and the gas G available gas storage area 2a of the fermenter 2 decreases and thereby the gas pressure is increased. It is also possible to the fermenter 2 already fermented nutrient medium M ', which via the line 8c was discharged, again via a line 8e supply in order to increase the shortest possible gas withdrawal without loss of pressure.

To control the gas pressure in the fermenter 2 now easy to perform, is the Re Geleinrichtung via signal lines - which for reasons of clarity in the 1 not shown - connected to the components described below. The biogas plant 1 has a first feed pump 31 which serves to ensure that the nutrient medium M, for example a primary sludge, fed to it into the fermenter 2 feed. A signaled by the control device shut-off valve 34 serves to the inflow of nutrient medium M to the first feed pump 31 to regulate. To the over the first feed pump 31 fed nutrient medium even more components, for example, from the fermenter 2 recirculated, partially fermented nutrient medium M 'or to add a co-ferment, is a controllable by the control device second feed pump 32 intended. valves 33a and 33b serve to supply the feed from the feed pumps 31 respectively. 32 to regulate the supplied medium.

The nutrient medium M thus formed becomes a feeder 10 the biogas plant 1 which will be described in detail below. This feeding device 10 is via a supply line 3 with an inlet opening 3 ' connected to the fermenter. By controlling the feed pumps 31 and 32 , the valves 33a . 33b and 34 and / or the feed device 10 Thus, it is possible in an advantageous manner to regulate the supply of the nutrient medium M accordingly.

The fermenter 2 has several withdrawal points 7a . 7b on, in the discharge lines 8a . 8b open, which adjustable by the regulator valves 9a . 9b can be opened and shut off. The about the sampling points 7a and or 7b from the fermenter 2 removed, completely or partially fermented nutrient medium M 'can then via a further discharge line 8c caused by a signaled by the control device valve 9c can be opened and closed, be removed. By appropriate regulation of the valves 9a - 9c Thus, it is again possible, the removal of the nutrient medium M 'from the fermenter 2 to control accordingly.

By regulating the supply of the nutrient medium M and / or the removal of the nutrient medium M 'by the control device, it is thus possible in a simple manner, the capacity of the fermenter 2 located nutrient medium M, M 'to regulate such that the pressure of the biogas produced by the fermentation of the nutrient medium M' below a certain limit, preferably below the atmospheric pressure remains. In the latter case, it is therefore no longer necessary, the fermenter 2 and thus the biogas plant 1 pressure-resistant, which significantly reduces their production and their maintenance and operating costs.

In the biogas plant described here 1 is further provided that the fermenter 2 to be supplied nutrient medium M is mixed with a gaseous medium G before its feed. This has the advantage that in the fermenter 2 introduced mixture of nutrient medium M and gaseous medium G for mixing in the fermenter 2 nutrient medium M provides by one from the inlet port 3 ' the supply line 3 outgoing nutrient medium flow S is generated, due to its caused by the gas admixture lower specific gravity in the fermenter 2 located nutrient medium M rises and so provides the same for a thorough mixing. In the described biogas plant 1 Therefore, in an advantageous manner, no facilities such as a stirrer, flow control or air inlet nozzles for a separately introduced air flow longer required. This reduces the production, operating and maintenance costs of the biogas plant in an advantageous manner 1 considerably.

The mixing of the in the fermenter 2 to be introduced nutrient medium M with the gaseous medium G is achieved in the case described here, that of the inlet opening 3 ' for the nutrient medium M upstream feeding device 10 as a mixer 10 ' is formed, which is supplied to both the nutrient medium M and the gaseous medium G and then these two components in the mixing device 10 ' be mixed together. The mixture of nutrient medium M and gaseous medium G thus formed is then supplied via the supply line 3 from the mixer 10 ' to the inlet opening 3 ' of the fermenter 2 directed.

For this purpose, it is provided that the mixing device 10 ' a first entrance 10a possesses, over which the nutrient medium M of the mixing device 10 ' can be fed. In the case described here, the nutrient medium M is primary sludge via the first feed pump 31 the first entrance 10a the mixing device 10 ' is supplied. The primary sludge is optionally still excess sludge, which optionally still contains a co-ferment, via the second feed pump 32 supplied, wherein the supply of primary sludge and / or secondary sludge via the valves 33a . 33b is controllable. Shut-off valves 34a and 34b allow the supply of primary sludge to the first feed pump 31 or from excess sludge to the second coating pump 32 to regulate.

The gaseous medium G becomes the mixing device 10 ' via a second entrance 10b fed. It is particularly advantageous if the gaseous medium G used for mixing the nutrient medium M is not at least partially removed from comes from an external gas source, but that in the fermenter 2 obtained biogas B is used. For this purpose, it is provided in the described embodiment that the gas storage area 2a of the fermenter 2 taken biogas B the second entrance 10b the mixing device 10 is supplied by one with a valve 11 provided gas line 4b to the mixing device 10 ' to be led.

It is preferably provided that the gaseous medium G before feeding into the mixing device 10 ' still in a gas compressor 12 compressed and via a gas pump 13 to the mixing device 10 ' is guided, so that in the mixing device 10 ' formed mixture of nutrient medium M and gaseous medium G with a sufficiently high pressure in the fermenter 2 is fed. Such a measure has the advantage that this from the inlet opening 3 ' of the fermenter 2 exiting mixture of nutrient medium M and gaseous medium G, which - as already mentioned - by this mixture a lower specific gravity than the other in the fermenter 2 located nutrient medium M has, by this pressurization rises to an even better extent and thereby for even better mixing of the fermenter 2 located nutrient medium M ensures.

The gas compressor can - if necessary - be used without addition of the nutrient medium M for feeding the gaseous medium G. This can be done in the fermenter 2 be located nutrient medium M, M 'homogenized.

Optionally, it can be provided that between the gas compressor 12 and the gas pump 13 a control valve 14 is arranged.

In the case described here, it is provided that the mixing device 10 ' not only the nutrient medium M - here: the sewage sludge - and the gaseous medium G - here: the obtained by the fermentation of the nutrient medium M biogas B - is supplied, but that is provided in an advantageous manner that the mixing device 10 ' also from the fermenter 2 over a line 8d taken, fermented nutrient medium M 'via a third input 10c is fed, mixed with the nutrient medium M and the gaseous medium G and then the mixture composed of the nutrient medium M and / or the recirculated, completely or partially fermented nutrient medium M 'and the gaseous medium G again into the fermenter 2 is fed. Such a procedure has the advantage that thereby a circulating operation of the fermenter 2 is made possible by the improved mixing in the fermenter 2 located nutrient medium M, M 'can be achieved. The procedure described makes it possible to dispense with a required in known systems, additional delivery unit.

To now the fermenter 2 supplying the required process heat for a rapid fermentation of the nutrient medium M supplied is provided in the described embodiment, that from the fermenter 2 taken biogas B - as already described - one here as a gas engine 6 ' trained consumer 6 is supplied to recover the heat required for the fermentation process. The gas engine 6 ' is via a supply line 6a and a discharge line 6b with a heat exchanger 16 connected to the gas engine 6 ' generated and over the lines 6a . 6b to the heat exchanger 16 transferred heat to the recirculated nutrient medium M 'emits and so for an energy input into the fermenter 2 provides. But it is also possible, instead of the recirculated nutrient medium M 'that of the biogas plant 1 supplied nutrient medium M, ie the primary sludge to heat in the aforementioned manner. It is also possible to dispense with the above-described manner of obtaining the process heat for accelerating the fermentation of the nutrient medium M and the fermenter 2 by means of an external source - for example, electrically, geothermally, by combustion of fossil fuels or vegetable or thermal residues, etc. - to heat.

It is preferably provided that - as in 1 indicated schematically - the mixing device 10 ' with the fermenter 2 connecting supply line 3 in one for cleaning the empty fermenter 2 already existing manhole is arranged so that thereby a simple and inexpensive way the feed of the fermenter 2 is possible without doing this expensive feedthroughs through the wall of the fermenter 2 and / or additional connections are required.

In summary, it should be noted that by the described procedure by a corresponding regulation of the supply and / or the removal of nutrient medium M or M 'in the fermenter 2 prevailing gas pressure below a certain value, preferably under the atmospheric pressure, can be maintained. an improved mixing of the nutrient medium M, M 'in the fermenter 2 achievable in a simple manner. The plant described is therefore characterized by low manufacturing, operating and maintenance costs and requires - if the latter alternative is realized - no regulatory approval.

Claims (19)

Biogas plant with a fermenter ( 2 ), in which a nutrient medium (M) can be introduced, by the Fermentation biogas (B) is produced, characterized in that the biogas plant ( 1 ) a pressure sensor ( 20 ), by which the pressure of the in the fermenter ( 2 ) located biogas (B) is detectable, which is a sensor signal of the pressure sensor ( 20 ) to a control device ( 30 ), which compares the actual pressure of the biogas (B) with a predetermined or predefinable setpoint pressure, and in that the control device adjusts the filling level of the fermenter ( 2 ) nutrient medium (M, M ') generating signal, by which the supply and / or the removal of the nutrient medium (M or M') in or out of the fermenter ( 2 ) is adjustable. Biogas plant according to claim 1, characterized that the predetermined and predetermined target pressure is less than or equal to atmospheric pressure is. Biogas plant according to claim 1, characterized in that the control device is a feed device ( 10 ) for the nutrient medium (M). Biogas plant according to claim 1, characterized in that the regulating device controls the inflow of the nutrient medium (M) regulating valves ( 33a . 33b . 34 ) and / or at least one feed pump ( 31 . 32 ) regulates. Biogas plant according to one of the preceding claims, characterized in that the control device ( 30 ) the effluent from in the fermenter ( 2 ) nutrient medium (M, M ') regulating valves ( 9a . 9b . 9c ) regulates. Biogas plant according to one of the preceding claims, characterized in that the fermenter ( 2 ) one or more exit points ( 7a . 7b ) for in the fermenter ( 2 ), completely or partially fermented nutrient medium (M '), which is controlled by the regulating device by the control valves ( 9a . 9b ) is openable and closable or are. Biogas plant according to one of the preceding claims, characterized in that the fermenter ( 2 ) upstream feeding device ( 10 ) a mixing device ( 10 ' ), in which the fermenter ( 2 ) to be supplied nutrient medium (M) and a gaseous medium (G) are mixable and that the thus formed mixture of nutrient medium (M) and gaseous medium (G) the fermenter ( 2 ) is supplied. Biogas plant according to claim 7, characterized in that the mixing device ( 10 ) a first input ( 10a ), over which the mixing device ( 10 ) the nutrient medium (M) is supplied. Biogas plant according to claim 7, characterized in that the mixing device ( 10 ' ) a second input ( 10b ), over which the mixing device ( 10 ' ) the gaseous medium (G) is supplied. Biogas plant according to claim 7, characterized in that the biogas plant ( 1 ) a gas line ( 12 ), through which from a gas storage area ( 2a ) of the fermenter ( 2 ) withdrawn biogas (B) the second input ( 10b ) of the mixing device ( 10 ' ) can be fed. Biogas plant according to claim 7, characterized in that the second input ( 10c ) the mixing device ( 10 ' ) a gas compressor ( 12 ) and / or a gas pump ( 13 ) is connected upstream. Biogas plant according to claim 7, characterized in that the mixing device ( 10 ' ) a third input ( 10c ), via which a fermenter ( 2 ) taken nutrient medium (M ') of the mixing device ( 10 ) can be fed. Biogas plant according to one of the preceding claims, characterized in that the biogas plant ( 1 ) a heat exchanger ( 16 ), through which the process medium heat required for fermentation can be supplied to the nutrient medium (M; M '). Method for regulating the pressure of a biogas plant with a fermenter, into which a nutrient medium (M) can be introduced, by the fermentation of which biogas (B) can be produced, characterized in that a gas sensor ( 20 ) the pressure of the in the fermenter ( 2 ) and a gas sensor ( 20 ) is conducted to a control device, and that the amount of the nutrient medium (M, M ') located in the fermenter is regulated by the control device in such a way that the control device ( 30 ) from the pressure sensor ( 20 ) detected actual pressure of the biogas (B) with a predetermined or predetermined setpoint pressure compares, and that at a low pressure of the gas storage area ( 2a ) of the fermenter ( 2 ) biogas (B) increases the supply of the nutrient medium (M) and / or the removal of the nutrient medium (M ') from the fermenter ( 2 ) and at too high a pressure of the gas storage area ( 2a ) located biogas (B) reduces the supply of nutrient medium (M) and / or the removal of nutrient medium (M ') is increased from the fermenter. Method according to claim 14, characterized in that that the predetermined or predeterminable pressure is less than or equal to the atmospheric pressure is. A method according to claim 14, characterized in that before feeding the nutrient medium (M) into the fermenter ( 2 ) the nutrient medium in a mixing device ( 10 ) with a gaseous Medium (G) is mixed and the thus formed substance / gas mixture in the fermenter ( 2 ) is introduced. A method according to claim 15, characterized in that the gaseous medium (G) of the mixing device ( 10 ) is supplied under pressure. Method according to one of the preceding claims, characterized in that the gaseous medium (G) in the fermenter ( 2 ) produced biogas (B) is used. Method according to one of claims 14 to 18, characterized in that the mixing device ( 10 ' ) from the fermenter ( 2 ) withdrawn nutrient medium (M ') is supplied.