DE102006028003B4 - Pressure safety device for fermentation tanks - Google Patents

Abstract

fermenter for the Biogas production with a housing in the fermenter interior Pressure fuse (10), characterized in that in the pressure fuse (10) a barrier fluid (12) is contained, wherein the pressure relief (10) in a built-in wardrobe (9) is housed and the built-in wardrobe (9) in a recess the fermenter wall (19) is arranged.

Description

Technical area

The The invention relates to a pressure safety device for fermentation vessels.

State of the art

biogas plants generate methane through a microbial degradation process of organic substances. The biogas is produced in a multi-stage process, fermentation or Digestion by the activity of anaerobic microorganisms, d. H. in the absence of air. The type of organism strains is essentially determined by the specific process parameters Temperature, substrate, pH, etc. determined. This will be a Adaptation of the microorganisms to the respective substrate is achieved, which makes it possible to degrade a variety of organic materials by fermentation.

organic Material has a high molecular structure from a chemical point of view in the individual process steps of a biogas plant by metabolic activity the microorganisms is degraded to low molecular weight building blocks. In addition to biogas, which consists essentially of methane and carbon dioxide, remains in the process chain as fermentation residue a mixture of water, not degraded organic material and inorganic components. Degraded are usually heavily ligninhaltige, woody Materials and cellulosic fabrics. Inorganic ingredients are minerals in the form of sand and stones, but also crystallized Salts.

headquarters Components of a biogas plant are the fermentation tanks (fermentors, Reactors, post-fermenters), in which the primary biological processes take place. As materials for the construction of the fermentors become common Concrete or steel plates (enamelled, coated or stainless steel) used.

The are in a biogas plant running microbial degradation processes strongly dependent on the fermenter temperature. For this reason will be the reactors mostly thermally insulated and with a heater (external Heat exchanger, Heating coils on the inner wall, heated agitators or underfloor heating) fitted.

For the mentioned microbial degradation processes can used both mesophilic and thermophilic microorganisms become. The degradation processes take place in the case of mesophilic microorganisms at temperatures between 20 and 40 ° C and in the case of thermophilic microorganisms at a temperature of around 55 ° C from.

The by bacteria in the fermenter or in any existing secondary fermenter from biomass such. Eg manure, Grass clippings, other agricultural residues and renewable Biogas produced in raw materials in the fermenter, in the post-fermenter and / or collected in an external gas storage. Fermenter, post-fermenter and / or external gas storage tanks are often equipped with an elastic roof (membrane) fitted.

in the For the purposes of the present invention, the term "fermenter" does not only refer to fermentors understood in itself, but any kind of bulky container, in Biogas produced by microbial degradation processes and the educated Biogas is collected. This is in addition to the fermenters especially to Nachgärer.

A Special provision must be made for overpressure or underpressure protection of the fermenter. In the fermenter it may be due to malfunctions namely both to build a negative pressure as well as to the emergence of an overpressure come.

One Underpressure may arise in the fermenter especially if the combined heat and power plant integrated in the biogas plant generates more gas withdraws from the fermenter as is produced there. cogeneration are common equipped with a vacuum switch, but which fail can. Due to the negative pressure in the fermenter drastic consequences such as the collapse of the entire roof construction of the fermenter, the maturation of the fermenter contents and the entry of oxygen into the fermenter with the formation of highly explosive gas mixtures, is an extra mechanical protection against negative pressure required at each fermenter and also prescribed.

To an overpressure In the fermenter it can come, if the cogeneration plant less Withdrawing gas from the fermenter when it is being produced or if a malfunction of the cogeneration plant is present. Combined heat and power plants are common with a pressure switch equipped, which automatically starts the combined heat and power plant with overpressure, this can just as fail as the vacuum switch. at Fermenters equipped with a gas storage foil can it at overpressure come to a burst of foil. For fermenters with a solid roof It can cause such severe damage come that the fermenter content expires or the fermenter completely collapses.

A additional Mechanical protection of the fermenter against overpressure as well as against negative pressure is therefore mandatory and also required by law.

in the For the purposes of the present invention, the term "pressure safety device" is understood to mean a safety device against Negative pressure and a fuse against overpressure summarized. is in the present application so from a pressure relief the Speech, such as being a fuse against both negative pressure also against overpressure to understand.

Usually Pressure fuses are attached to the outer wall of the fermenter. It happens frequently on the problem that the contained in the pressure relief sealing water freezes and the pressure relief thus their functionality loses. As a remedy is usually a glycol-water mixture used, whose melting point is well below 0 ° C.

Indeed also offers this measure no final Safety, as it is due to condensing in the pressure relief Water to a dilution the water / glycol mixture comes, causing the melting point to rise and it may come back to a freeze of the liquid.

When further consequences To prevent freezing, electrical heating tapes are around the Pressure fuse wound and the device permanently heated. In case of a power failure, however, this heater turns off and it can in turn come to a freeze of the pressure relief.

Various vessels are already known from the prior art, in the interior of which a pressure safety device is provided. So revealed the DE 87 13 377 U1 a gas vent valve located in the interior of drums, which can reduce the pressure in the tank. The DE 87 08 236 U1 describes a device provided inside the container for preventing pressure build-up in the container. Finally, out of the DE 81 34 781 U1 a pressure relief valve for a gas-tight packaging bag is known, which is attached to the inside of the bag attached to the bag wall.

In addition, according to the diving bell principle working pressure compensation valves in various forms from the prior art are known. That's how it describes DE 24 27 868 A1 a device for differential pressure measurement of gaseous substances, the DE 1 105 842 B an automatic liquid immersion closure, the DE 490 259 A a backflow valve to protect gas meters and piping, the DE 349 911 A a mixer for two different gases, and finally the one filed on February 16, 1938 GB 509 942 A a device for regulating the pressure in bunkers.

the described prior art is thus not the pressure relief of fermenters and other biogas storage tanks satisfactory solution too remove.

Presentation of the invention

Here implements the invention. The invention as characterized in the claims is the task underlying a fermenter for biogas production to provide with a pressure relief that the disadvantages of Prior art avoids.

These The object is achieved by the Fermenter with pressure protection according to independent claim 1 solved. Further advantageous details, aspects and embodiments of the invention arise from the dependent ones claims, the description and the figures.

The The present invention provides a digester for biogas production a housed in the fermenter interior pressure relief available, wherein the pressure relief a barrier fluid contains. The pressure relief is housed in a built-in wardrobe, where the built-in closet arranged in a recess of the fermenter wall is. By using a built-in wardrobe is a hassle and cost-effective installation the pressure relief in the fermenter possible.

Of the The present invention is based on the idea that for safe Preventing the freezing of the fermenter pressure relief no special design the pressure relief itself is required. Freezing the barrier fluid in the pressure relief can rather by a suitable placement the pressure relief can be prevented at the fermenter. Namely, how provided according to the invention, the pressure relief housed in the fermenter interior, so prevail at the place of pressure relief at all times, essentially in the fermenter interior present temperatures. Because the microbial conversion of biomass to biogas usually at temperatures between 20 and 55 ° C, in each Case but takes place at temperatures well above 0 ° C, freezing is the barrier fluid the pressure relief excluded. Even with a longer standstill In the fermenter interior the temperature of the fermenter interior sinks only up to 3 days very slowly, thereby freezing the pressure relief even at a complete failure of the biogas plant is prevented.

By the permanent temperature control of the pressure fuse to the temperature of the fermenter interior is unnecessary also the use of expensive antifreeze as a barrier fluid.

As a pressure relief is a per se from the Prior art known pressure siphon used. In the pressure relief, a float plate is mounted, which dips into a liquid for sealing. As a result, the gas space of the plant (fermenter) is closed to the atmosphere. The liquid reservoir (barrier fluid) forms a pressure siphon.

The Operation of the pressure siphon is based on the principle of pressure and Backpressure. The floating plate acts with its weight on the gas pressure in the fermenter. about weights mounted on the float plate may be the trigger pressure be set. If the internal pressure of the fermenter reaches one preset value of, for example, 2 mbar (corresponding to 2 cm water column), so the float plate is moved upwards. This can be biogas unhindered by a tube to the fermenter interior open pipe, through the pressure relief and then through an outwardly open pipe from the fermenter flow out.

Of the Floater plate dives into the barrier liquid with three support feet ahead one. If there is a negative pressure in the fermenter, for example 2.5 mbar, the barrier liquid is through the comparatively higher atmospheric pressure displaced into the fermenter. This can be done by the outward open air pipe from the environment into the fermenter. It In this way, a pressure equilibrium arises again the fermenter interior and the environment.

According to one preferred embodiment of present invention is the pressure relief in a fermenter to the interior housed in the open recess of the fermenter wall. A niche in the fermenter wall provides a safe and easily accessible Location for the pressure relief.

The Fermenterwand becomes with the establishment of the fermenter with a recess in standard size, in the built-in cabinet then only fit to be used needs. The installation of the pressure relief in the built-in wardrobe can be done in advance respectively. The outside dimensions of the built-in wardrobe amount for example, around 105 cm × 65 cm × 25 cm, the depth of the built-in wardrobe of about 25 cm is about the thickness the fermenter wall corresponds. The built-in wardrobe can also be used for The fermenter interior projecting out of the fermenter wall.

According to one another preferred embodiment the recess completely breaks through the fermenter wall. In In this case, a wall of the built-in cabinet is part of the outer wall of the fermenter visible. In this embodiment, the tube of the Pressure relief (the "blow-off"), by the overpressure case Biogas from the fermenter flows into the environment and in the vacuum ambient air into the fermenter, be pre-assembled in a simple manner. Because the back wall of the built-in wardrobe is the outer wall of the fermenter, this rear wall only needs to be provided with a standardized opening through which the inlet / outlet of the pressure relief is performed.

Of the Built-in wardrobe with the pressure relief is near the top edge of the fermenter introduced into the fermenter wall. For one thing must be the built-in wardrobe of course located in the area of the fermenter, that of the biogas formed filled is and must not be overflowed by the substrate. Give to another the "safety rules for agricultural Biogas plants "structural Limits for the estuary the blow-off line of the biogas. The mouth of the blow-off must namely at least 3 m above the ground and at least 1 m above the roof or container edge lead. Since the other end of the discharge line opens into the pressure relief offers It's about the built-in wardrobe with the pressure relief near the top edge to place the fermenter.

Prefers is additional in the built-in wardrobe a gas pressure sensor attached. An additional gas pressure sensor with Pressure display allows on the one hand the recording of the pressure development over time in the fermenter room and on the other a visual check of the Pressure conditions, making an earlier Respond to malfunctions is possible. By attaching the gas pressure sensor in the built-in closet is the Pressure sensor protected and easily accessible assembled.

Also preferred is an embodiment according to the in the wall of the built-in wardrobe additionally a sampling opening for samples the fermenter content is provided. This will make it possible samples of the fermenter content, without the fermenter interior to have to enter.

According to one another preferred embodiment The present invention is in the walls of the built-in wardrobe two viewing windows provided. The viewing windows allow an observation of the fermenter substrate, without the fermenter interior to have to enter.

According to a further preferred embodiment of the present invention, a sight glass is provided on the pressure relief. Through the sight glass, the liquid level of the sealing liquid of the pressure relief is visible. About a refill tube, the barrier liquid can be filled to the extent that the level to the top of the sight glass rises. Possibly superfluous barrier liquid can flow through the fermenter interior towards the open pipe pressure relief in the fermenter.

Maintenance work such as B. controlling and refilling the pressure relief can be comfortable performed from a pedestal become. This also applies to Sampling over the integrated removal opening as well as for Cleaning work on the gas pressure sensor. Each fermenter has its own outside by default Podium at the same position.

The Pressure relief is for cleaning and adjustment purposes with two removable Provided with blind flanges.

Prefers The built-in cupboard is made of stainless steel, which provides sufficient corrosion resistance and thus life of the cabinet is guaranteed.

The The present invention also includes the use of a pressure relief device for installation in a recess open towards the fermenter interior a fermenter wall.

Brief description of the drawings

to Illustration of the invention and to illustrate their advantages below exemplary embodiments specified. These embodiments should be explained in connection with the drawings. It goes without saying it goes without saying that these details are not intended to limit the invention. Show it

1 a schematic representation of a typical agricultural biogas plant;

2a a schematic representation of a pressure relief;

2 B a schematic representation of the pressure relief of 2a at overpressure in the fermenter;

2c a schematic representation of the pressure relief of 2a at negative pressure in the fermenter;

3 a section through a fermenter wall with accommodated in a built-in cabinet pressure relief.

Ways to execute the invention

1 shows a schematic representation of a typical agricultural biogas plant. By methanogenic bacteria is in the fermenter 1 and post-fermenter 2 Biomass such. As manure, grass clippings and other agricultural residues are converted into biogas. This is in Nachgärer (with elastic roof 3 ) and in the finest bubbles in a PBR 4 initiated. In this are biogas-tolerant, photosynthesis-driving microorganisms.

The Carbon dioxide dissolves yourself in the aqueous system and is released by the microorganisms by means of light in oxygen and Converted biomass. Minor components in the gas such. B. ammonia and dissolve hydrogen sulfide in the aqueous System and are used as trace components of microorganisms metabolized. More of the microorganisms needed and not provided by the gas trace elements must be separated be dosed. Methane dissolves hardly and is not degraded by the organisms.

The undissolved gases (especially methane and oxygen) are passed through a gas-liquid separator 5 separated from the liquid in the PBR. The clean gas thus processed becomes a second elastic hood 6 on the post-fermenter. In the wall of the Nachgärers 2 is a built-in wardrobe with a pressure relief inserted.

Part of the use in the CHP 7 Waste heat generated can be used to maintain the temperature in the PBR in a special sheathing 8th be directed. The biomass produced in the PBR is fermented back to biogas in the fermenter.

The 2a shows a schematic representation of a pressure relief 10 , In the pressure protection 10 is a float plate 11 mounted, for sealing in a liquid 12 dips. As a result, the gas space of the plant (fermenter) is closed to the atmosphere. The float plate 11 Counteracts the gas pressure in the fermenter with its weight. About on the float plate 11 mounted weights 13 the trigger pressure can be adjusted. The pressure relief 10 has a sight glass 16 and a refill tube 17 on. Through the sight glass 16 is the fluid level of the barrier fluid 12 visible, noticeable. About the refill tube 17 can the barrier liquid 12 as far as filled, that the level to the upper edge of the sight glass 16 increases. Eventually unnecessary sealing liquid 12 can through the pipe 18 drain into the fermenter.

The 2 B shows a schematic representation of a pressure relief in the presence of an overpressure in the fermenter. If the internal pressure of the fermenter reaches a pre-set value of, for example, 2 mbar (corresponding to 2 cm water column), then the float plate becomes 11 upwards moved. This allows the biogas from the fermenter interior through the pipe 18 and the pipe open to the outside 14 flow unhindered out of the fermenter.

The 2c shows a schematic representation of a pressure siphon in the presence of a negative pressure in the fermenter. The float plate 11 dives with three support feet 15 ahead in the barrier liquid 12 one. If a negative pressure of, for example, 2.5 mbar occurs in the fermenter, the barrier liquid becomes 12 displaced by the comparatively higher atmospheric pressure in the fermenter. Through the connection to an outwardly open pipe 14 can flow air into the fermenter from the outside. It adjusts in this way again a pressure balance between the fermenter interior and the environment.

The 3 shows a section through a fermenter wall 19 with one in the built-in wardrobe 9 housed pressure relief 10 , Through the tube open to the outside 14 In the case of a negative pressure in the fermenter, air can flow into the fermenter from the outside. In case of overpressure in the fermenter, biogas from the fermenter can pass through the tube 18 and the pipe open to the outside 14 flow out. In the embodiment shown, the built-in closet jumps towards the fermenter interior out of the fermenter wall 19 in front. The built-in wardrobe 9 is in addition to the firmly connected to the built-in cabinet panels 20 at the fermenter wall 19 attached.

1

fermenter

2

secondary fermenter

3

elastic top, roof

4

photobioreactor

5

Gas-liquid separator

6

elastic Hood

7

CHP

8th

jacket

9

built-in wardrobe

10

pressure safety

11

float Teller

12

buffer fluid

13

weights

14

to Outside open tube

15

Feet of the float plate

16

sight glass

17

refill tube

18

pipe to the fermenter interior

19

fermenter wall

20

mounting plates

Claims (9)

Fermenter for biogas production with a pressure fuse located in the fermenter interior ( 10 ), characterized in that in the pressure fuse ( 10 ) a barrier liquid ( 12 ), the pressure relief ( 10 ) in a built-in wardrobe ( 9 ) is housed and the built-in wardrobe ( 9 ) in a recess of the fermenter wall ( 19 ) is arranged. Fermenter according to claim 1, characterized in that in the built-in closet ( 9 ) In addition, a gas pressure sensor is mounted. Fermenter according to at least one of claims 1 and 2, characterized in that in the wall of the built-in cabinet ( 9 ) In addition, a removal opening for samples of the fermenter content is provided. Fermenter according to at least one of claims 1 to 3, characterized in that in the walls of the built-in cabinet ( 9 ) two viewing windows are provided. Fermenter according to at least one of claims 1 to 4, characterized in that the built-in cupboard ( 9 ) is made of stainless steel. Fermenter according to at least one of claims 1 to 5, characterized in that in the pressure fuse ( 10 ) a sight glass ( 16 ) is provided. Fermenter according to at least one of claims 1 to 6, characterized in that the pressure relief ( 10 ) a refill tube ( 17 ) for refilling the sealing liquid ( 12 ) having. Fermenter according to at least one of claims 1 to 7, characterized in that the pressure relief ( 10 ) a tube open to the fermenter interior ( 18 ), through which excess barrier fluid can drain into the fermenter. Use of a pressure fuse ( 10 ) as defined in claims 1 to 8 for installation in a fermenter interior.