DE20015808U1 - Device for fermenter overpressure / underpressure protection of a biogas plant - Google Patents

Description

G 216BG OO

Description

Device for fermenter overpressure/underpressure protection of a biogas plant

The invention relates to a device for protecting the fermenter from overpressure and underpressure in a biogas plant according to the preamble of claim 1.

In biogas plants, a fermentation process takes place in which organic substances such as grass, stable manure, liquid manure, straw and the like are gasified. This fermentation process takes place in a fermentation tank in which the organic substances are mixed with liquid and the fermentation or gasification process is carried out under aerobic or anaerobic conditions by microorganisms. The biogases produced during fermentation collect in an upper fermentation tank area and can be used directly to generate energy, e.g. as heating gas for generating electricity in downstream internal combustion engines with electric generators.

When gas is produced, a relatively low overpressure of, for example, 20 mbar is usually created. The fermenter vessels are designed in such a way that no damage to vessels and pipes can occur at these low overpressures.

Especially when the fermenter is filled quickly and improperly or when there are irregularities in the fermentation process, for example

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In the event of deflagrations, there is a risk of either a relatively slow or sudden increase in pressure, which can lead to overpressure damage to the fermenter and connected functional components.

For example, to fill the fermenter tank with organic solids, it is known to install a shaft that is open at the top next to the fermenter tank that is covered at the top and that is connected to the fermenter tank in a gas-tight manner through an opening below the liquid level. When larger quantities of solids are thrown into such a shaft

There is a risk that these will jam together to form a plug, which after a certain time can suddenly slide into the fermenter tank. The small diameter of the shaft compared to the large diameter of the fermenter tank creates the effect of a hydraulic press. This has already caused concrete covers on fermenter tanks to be lifted off and moved. Similar damage, which leads to long downtimes and considerable repair costs, can also be caused by process-related pressure increases, although relatively small increases in excess pressure are sufficient due to the large cover areas.

In an alternative known design, fermenter containers are not covered with a concrete cover, but with a covering film, which is usually held laterally by water-filled hoses in a channel on the top of the fermenter side walls. Such a covering film bulges due to the gas generation and gas storage. However, if the excess pressure is too great, the film under the water hose weight is pulled out by excessive bulging, which means that the covering film is no longer secured and can be destroyed by being thrown around in strong winds, for example, or can damage other parts. In addition, all of the previously stored gas is lost, causing considerable odor nuisance.

Similar damage can be caused in the opposite direction by inadmissible negative pressures, which can arise, for example, when liquid drains quickly from the fermenter vessel.

A variety of different pressure relief devices are generally known for containers, which are designed as spring-loaded valves or weight-loaded flaps, for example. These known pressure relief devices are generally not suitable for use in biogas plants because they are not suitable for rough and dirty operation in conjunction with the fermentation liquid containing solids, or because they would require too much maintenance.

In addition, a biogas plant for the fermentation of organic substances is known with a fermenter tank and a stirring unit that is height-adjustable on a vertical support rod. A fermenter ceiling wall contains an agitator opening through which the support rod and the stirring unit are introduced into the fermenter tank. Above the agitator opening, a dome is attached in a gas-tight manner as a service shaft, into which the stirring unit can be moved from the fermenter tank. The support rod is also led out of the area of the dome roof in a gas-tight manner by means of a dip cup arrangement and is rotatably mounted. Such a dome, which can be accessed by a service technician, makes servicing the stirring device much easier.

The object of the invention is to provide a functional device for protecting against fermenter overpressure/underpressure, adapted to the conditions of a fermenter of a biogas plant.

This object is solved with the features of claim 1.

According to claim 1, the device for fermenter overpressure/underpressure protection comprises a gas pipe, on which at a gas pipe end region

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as a connection area, connecting parts are attached for connecting to the gas pipe of the fermenter. At the opposite gas pipe end area, an open immersion cup is connected in an immersion cup arrangement, which surrounds the gas pipe end area and into which an end-side gas pipe socket with a socket projection protrudes. The socket projection and the immersion cup are axially aligned approximately vertically when installed, since the immersion cup must accommodate a water filling with a horizontal water level.

A safety cover is hinged to the immersion cup and/or the gas pipe end area. In its closed position, the safety cover, with a tightly connected immersion sleeve as the immersion sleeve cover part, extends from above over the edge of the gas pipe socket with a pipe cover and with a lateral distance such that at least one gas exchange gap to the environment remains between the immersion sleeve cover part and the immersion cup.

A refill pipe is installed in the immersion cup, through which water can be poured into and refilled into the immersion cup, whereby the water level is determined by the upper edge of the gas pipe socket and any excess water flows through the gas pipe into the fermenter.

When the fermenter is in operation, there is gas at the respective operating pressure in the volume between the water level in the immersion cup and the immersed immersion sleeve. The function as an overpressure/underpressure safety device arises when the operating pressure gradually increases or decreases to inadmissible pressure values because gas bubbles out from under the lower edge of the immersed immersion sleeve and from the gas exchange gap to provide an overpressure safety device, or air enters the fermenter via the gas pipe in this way to provide a vacuum safety device.

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In addition to this function of an overpressure/underpressure protection by a gas or air exchange via the gas exchange gap and the water bath, a further overpressure protection, in particular for a rapid sudden increase in pressure, is created in that the immersion sleeve cover part can then be lifted off and opened to release the gas pipe socket opening for a rapid overpressure reduction.

This provides effective protection against pressure damage both for slow pressure changes and for rapid pressure increases, for example in the case of deflagrations. The safety device responds even to small, impermissible pressure fluctuations, with the response threshold being determined by the pipe overlap between the gas pipe socket and the immersion sleeve and preferably being set to a value of approx. 40 mbar.

The design of the device is simple and cost-effective and is ideally suited to the harsh operation of biogas in the agricultural sector, particularly due to its low-maintenance operation. In addition, there are no problems with explosion protection in the gas sector.

In a preferred embodiment according to claim 2, the gas pipe is a vertically mountable straight pipe section as a standpipe with a connecting flange at the end. Such a standpipe can simply be chosen to be long enough that the gas outlet opening is arranged above two meters above the ground in accordance with current regulations.

In an embodiment according to claim 3 that is easy to manufacture and functions well, the gas pipe, the immersion cup side wall and the immersion sleeve are made of concentrically arranged pipe sections of different diameters. Further optimizations can be carried out by choosing the diameters.

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According to claim 4, the upper cover wall covers the immersion cup from above, wherein the cover wall is held at a distance from the upper edge of the immersion cup in the closed position by means of a stop spacer, so that a circumferential annular gap is formed as a gas exchange gap. Such an arrangement counteracts, for example, rapid evaporation of water in the immersion cup.

According to claim 5, the safety cover can be opened into an open position up to the dead center position against a stop to release the nozzle opening. As a result, it advantageously falls back automatically into the closed position after an excess pressure has been released, so that the gas pipe is only open during the pressure release.

For a fermenter with a film cover, claim 6 claims a preferred embodiment in which a tension cable fixed on one side is stretched over the cover film. This creates a tension due to a rope movement in the event of excess pressure in the fermenter with a bulging of the cover film at the other end of the tension cable. This end of the tension cable is connected directly or indirectly via at least one cable deflection to an opening device of the safety cover. By suitably adjusting the effective length of the tension cable, it can be achieved that in the event of an impermissible excess pressure with a correspondingly high bulging of the cover film, the safety cover is pulled open to release the gas pipe opening.

According to claim 7, such an opening device can be created simply by a lever connected to the upper cover wall, to which the pull cable engages. According to claim 8, a pre-dead center stop can also be formed on such a lever at its free lever end opposite the immersion cup, wherein in a simple construction a cable deflection element can be connected to the gas pipe.

In a preferred embodiment according to claim 9, the refill pipe for the water in the immersion cup is laid in the gas pipe and is led with a pipe bend over the upper edge of the nozzle into the filling area of the immersion cup. Since the gas produced by the fermentation process is warm, an automatic heating system is created for the water inlet and the immersion cup as antifreeze protection, so that additional antifreeze devices can be omitted.

&iacgr;&ogr; The development according to claim 10 ensures that the safety device operates practically completely maintenance-free. For this purpose, the refill pipe is connected to the water supply via a controllable solenoid valve, whereby a control for refilling should take place at certain time intervals. Since a fermenter filling using a fermenter filling pump is required at certain time intervals anyway, a dip cup refill can also be advantageously coupled together with a control of the fermenter filling pump. The refill quantity for the dip cup is not critical, since if it is overfilled, it simply runs through the gas pipe into the fermenter.

The response threshold for the overpressure/underpressure protection depends on the immersion depth of the immersion sleeve below the water level of the immersion cup. When manufacturing the device, a response threshold suitable for normal conditions can be set. However, it can also be expedient to make this immersion depth and thus the response threshold adjustable according to claim 11, so that adaptations to special conditions can be carried out.

In a particularly compact and easy-to-install arrangement according to claim 12, the device with the gas pipe is flanged to a roof opening of a service shaft known per se. In principle, however, the

⁹ · · · m &lgr;. m.

Gas pipe with an opening of the fermenter vessel, for example directly connected to an opening of a fermenter cover.

The invention is explained in more detail using a drawing.

Show it:

Fig. 1 shows a schematic cross-section through a biogas plant with a fermenter and a device for fermenter overpressure/underpressure protection,

Fig. 2 is a schematic side view of a device for fermenter overpressure/underpressure protection,

Fig. 3 is a schematic plan view of the representation according to Fig. 2, and

Fig. 4 shows a schematic cross section through an alternative embodiment of a biogas plant with a fermenter tank and a device for fermenter overpressure/underpressure protection.

Fig. 1 shows a schematic representation of part of a biogas plant 1 for the fermentation of organic substances. This biogas plant 1 comprises a fermenter tank 2 with a stirring unit 4 arranged on a vertical support rod 3 so that its height can be adjusted. An agitator opening 6 is formed in a fermenter ceiling wall 5, through which the support rod 3 and the stirring unit 4 are introduced into the fermenter tank 2.

Furthermore, a dome 7 is mounted gas-tight above the agitator opening 6 as a service shaft, in which the agitator unit 4 can be moved out of the fermenter vessel 2.

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As can also be seen from Fig. 1, the support rod 3 is guided in a gas-tight manner by means of a dip cup arrangement 8 over the area of the dome roof and is mounted so that it can rotate. The dome 7 is designed in such a way that a service technician can walk onto it and carry out service work on the stirring device 4 there.

As can also be seen from Fig. 1, a device 9 for protecting against overpressure and underpressure in the fermenter is arranged on the side of the dome 7, the basic structure of which can be seen better in Fig. 2, which shows the device 9 in a more detailed schematic representation. It can be seen from Fig. 2 that the device 9 has a gas pipe 10, the gas pipe 10 being a vertically mountable, straight pipe section as a standpipe with a connection flange 11 at the end. The gas pipe 10 is connected to the gas space of the fermenter container 2 with a first gas pipe end region 12, while an open immersion cup 14 is connected to the opposite second gas pipe end region 13, which surrounds the second gas pipe end region 13 and into which the gas pipe end region 13 projects with a nozzle projection 15.

Furthermore, a safety cover 16 is attached to the immersion cup 14 and can be opened via a hinge not shown in detail here.

As can also be seen from Fig. 2, the safety cover 16 in its closed position shown in Fig. 2 with a tightly connected immersion sleeve 17 overlaps the gas pipe socket edge from above with a pipe cover and with a lateral distance. An upper cover wall 18 of the safety cover 16 covers the immersion cup 14 from above, whereby this cover wall 18 in the closed position of the safety cover 16 is held at a distance by means of a stop spacer 19, which is only shown very schematically in Fig. 2.

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held by the upper edge of the immersion cup, so that a circumferential annular gap is formed as a gas exchange gap 20.

Furthermore, a refill pipe 21 is installed in the immersion cup 14, via which water 22 can be filled into and refilled into the immersion cup 14, wherein the water level is determined by the upper gas pipe socket edge and an excess amount of water flows through the gas pipe 10 into the fermenter container 2.

As can also be seen from Fig. 2, the refill pipe 21 is laid in the gas pipe 10 &iacgr;&ogr; and is led with a pipe bend over the upper edge of the nozzle into the filling area of the immersion cup 14.

Furthermore, the refill pipe 21, as shown only schematically in the illustration in Fig. 2, is connected to a water supply via a controllable solenoid valve 23, wherein a control for refilling can be carried out at certain time intervals, preferably together with a control 24 of a fermenter filling pump, not shown here.

When the fermenter is in operation, there is gas in the volume between the water level in the immersion cup 14 and the immersed immersion sleeve 17 with the respective operating pressure. If the inadmissible operating pressure gradually increases or decreases, gas is blown out in bubble form from under the lower edge of the immersion sleeve 17 and from the gas exchange gap 20 as an overpressure safety device, or air can penetrate into the fermenter when used as a negative pressure safety device. The immersion depth of the immersion sleeve 17 and thus the response threshold is shown in Fig. 2 with reference number 32 only schematically and as an example.

As shown schematically and in dashed lines in Fig. 1, in the event of such a rapid pressure increase, the immersion sleeve cover part can be opened to release the gas pipe socket opening for rapid overpressure relief.

Fig. 4 shows an alternative embodiment of a part of a biogas plant 26, in which a fermenter container 27 has a film cover, with a tension cable 29 fixed on one side, which is shown in broken lines and schematically in the illustration in Fig. 4, being stretched over this film 28, so that in the event of excess pressure in the fermenter and a resulting bulging of the film cover 28, a tension is created at the other end of the tension cable 30, with this end of the tension cable 30 being connected to an opening device 33 of the safety cover 16 via several cable deflections 31. The

The opening device 33 comprises, as can also be seen from Fig. 2 and Fig. 3, a lever 34 connected to the upper cover wall 18, which is attached in the hinge area and protrudes laterally from the safety cover 16. The pull cable end 30 is connected to the free lever end with the pull direction directed approximately vertically downwards. The safety cover 16 can basically be opened in an open position up to the dead center position against a stop 25 to release the nozzle opening and can be automatically moved back into the closed position by its weight.

Claims (12)

1. Device for fermenter overpressure/underpressure protection of a biogas plant, characterized in that
that the device has a gas pipe,
that connecting parts for connection to the gas space of the fermenter are attached to a gas pipe end area as a connection area,
that an open immersion cup is connected to the opposite gas pipe end area, which surrounds the gas pipe end area and into which an end-side gas pipe nozzle with a nozzle projection protrudes, wherein at least the nozzle projection and the immersion cup are axially aligned approximately vertically in the installed state,
that a safety cover is attached to the immersion cup and/or the gas pipe end area and can be opened via a hinge,
that the safety cover in its closed position with a tightly connected immersion sleeve as immersion sleeve cover part overlaps the gas pipe socket edge from above with a pipe cover and a lateral distance, such that at least one gas exchange gap to the environment remains between the immersion sleeve cover part and the immersion cup,
that a refill pipe is installed in the immersion cup, through which water can be filled into the immersion cup and refilled, whereby the water level is determined by the upper edge of the gas pipe socket and an excess amount of water flows through the gas pipe into the fermenter,
that when the fermenter is in operation, gas is present in the volume between the water level in the immersion cup and the immersed immersion sleeve at the respective operating pressure and when the operating pressure gradually increases or decreases to inadmissible pressure values, gas bubbles out from under the lower edge of the immersion sleeve and from the gas exchange gap as an overpressure protection or air penetrates into the fermenter in this way as a negative pressure protection, and
that in the event of a rapid increase in pressure, the immersion sleeve cover part can be opened to release the gas pipe socket opening for rapid overpressure relief. 2. Device according to claim 1, characterized in that the gas pipe is a vertically mountable, straight pipe section as a standpipe with an end connection flange. 3. Device according to claim 1 or claim 2, characterized in that the gas pipe, the immersion cup side wall and the immersion sleeve are formed from concentrically arranged pipe sections of different diameters. 4. Device according to one of claims 1 to claim 3, characterized in that the upper cover wall covers the immersion cup from above, and that the cover wall is held at a distance from the upper edge of the immersion cup in the closed position of the safety cover by means of a stop spacer, wherein a circumferential annular gap is formed as a gas exchange gap. 5. Device according to one of claims 1 to claim 4, characterized in that the safety cover can be opened into an open position up to the dead center position against a stop to release the nozzle opening and can be automatically moved back into the closed position by its weight. 6. Device according to one of claims 1 to claim 5, characterized in that
that in a fermenter with a foil cover, a tension rope is stretched over the cover foil on one side, so that in the event of excess pressure in the fermenter, a bulge in the cover foil creates a tension at the other end of the tension rope, and
that this traction cable end is connected directly or indirectly via at least one cable deflection to an opening device of the safety cover. 7. Device according to claim 6, characterized in
that the opening device consists of a lever connected to the upper cover wall, which is mounted in the hinge area and protrudes laterally from the safety cover, and
that the free end of the lever is connected to the pulling end with the pulling direction directed approximately vertically downwards. 8. Device according to claim 7, characterized in that a pre-dead center stop is formed at the free end of the lever opposite the immersion cup and a cable deflection element is connected to the gas pipe. 9. Device according to one of claims 1 to claim 8, characterized in that the refill pipe is laid in the gas pipe and is guided with a pipe bend over the upper edge of the nozzle into the filling area of the immersion cup. 10. Device according to one of claims 1 to claim 9, characterized in that the refill pipe is connected to the water supply via a controllable solenoid valve, and a control for refilling can be carried out at definable time intervals, preferably together with a control of a fermenter filling pump. 11. Device according to one of claims 1 to claim 10, characterized in that the pipe coverage and thus the immersion depth of the immersion sleeve in the immersion cup is adjustable. 12. Device according to one of claims 1 to claim 11, characterized in that the device with the gas pipe as a standpipe is flanged to a roof opening of a service shaft.