DE102012218956A1 - Gas cleaning device - Google Patents

Abstract

A gas purification device for purifying biogas from a biogas plant or digester gas from a sewage treatment plant is improved in terms of economic operation without additional energy or material supply in that a cooling space (15) is provided in which a pipe cooler coil (3) is arranged , the inlet end (31) of which is connected to a supply line (18) for the introduction of unpurified biogas / digester gas, that an outlet end (32) of the pipe cooler coil (3) is connected to a separator device (4) which is located below the pipe cooler coil (3) is arranged in the cooling space (15), the water vapor contained in the unpurified biogas / digester gas condenses out with impurities in the pipe cooler coil (3) and the condensate is separated in the separator device (4) from the thus purified biogas / digester gas, which is discharged from a clean gas outlet (61 ) the separator device (4) can be removed.

Description

The present invention relates to a gas purification device for the purification of biogas from a biogas plant or fermentation gas from a sewage treatment plant.

The biogas consists of methane and CO ₂ and contains, inter alia, hydrogen sulfide H ₂ S and other sulfur and silicon compounds H ₂ S is toxic and can damage the power generation, for example, provided in a cogeneration plant engines or other components of Faulgasverwertungsanlagen, because of the sulfur compounds together with the plentiful in the digestion gas at a digestion temperature of 30 ° C to 50 ° C water vapor forms sulfuric acid, which can be deposited for example in the engine oil of the participating engines. Similar negative effects have other impurities contained in the fermentation gas.

Usually, a small amount of air is blown into the digester to remove hydrogen sulfide. Special bacteria then convert the H ₂ S gas into pure sulfur. The cleaning by washing with solvents, by absorption on activated carbon or by freezing is also known. The known methods are expensive and the injection of air deteriorates the gas quality.

Gas purification reduces the concentration of impurities in the digester gas and thus significantly increases the service life of the digester gas utilization plants. Unfortunately, the operation of the digester cleaning devices requires additional energy, e.g. for the operation of pumps and cooling devices. Consumables such as activated carbon or solvents have to be renewed regularly, causing material costs and maintenance costs. During maintenance work, the operation of the cleaning system and the supply of digester gas must be interrupted. There is a risk of explosion and health hazards for the operating personnel.

To avoid the disadvantages mentioned and in particular to save costs, the invention proposes that a cooling space is provided, in which at least one tube cooler coil is arranged, whose inlet end is connected to a supply line for the introduction of unpurified biogas / biogas, that an outlet end of the Pipe cooler coil is connected to a separator, which is arranged below the tube cooler coil in the cool refrigerator, so that the water contained in the unpurified biogas / fermentation gas condensed with impurities in the tube cooler coil and the condensate is deposited in the separator from the thus purified biogas / digester gas, which a cleaning outlet of the separator can be removed. In this condensation process according to the invention, the undesirable constituents in the biogas / fermentation gas are washed out with. In biogas, this mainly affects H ₂ S and, in the case of digester gas from sewage treatment plants, also silanes and siloxanes. In this case, the invention requires neither activated carbon, nor additional consumables and comes even without the supply of external energy. Only the resulting condensate with the pollutants must be disposed of.

In an advantageous embodiment of the invention it is provided that the cooling space is configured as a cool condensate shaft and arranged below the ground level, preferably at a depth of 1.5 m or lower. Such a condensate tray can be easily introduced into the ground during the construction of the biogas plant. The bottom plate of the biogas plant is then easily adapted to the accessible shaft.

In a preferred embodiment of the invention, the tube cooler coil is helically or spirally configured with substantially horizontal turns extending in the condensate tray over a height range of about 1.2 m. The tube cooler snake is thus many meters long and ensures that the coming of the digester biogas / digester gas can cool down slowly and completely. Originally, the biogas / digester gas has a temperature between 30 ° C and 50 ° C and is 100% saturated with moisture. This moisture is condensed in the tube cooler coil, which is preferably made of stainless steel, with the heat of condensation being discharged via the tube cooler coil to the cooling air flowing through the cooling chamber.

In a further embodiment of the invention, at least one vent pipe is provided for introducing cooling air into the cooling space, the upper end ends for sucking in ambient air outdoors and the lower end opens into the bottom region of the cooling space, where the cooling air exits. It can also be provided a plurality of ventilation pipes or ventilation openings.

The invention is further improved by the measure that at least one chimney is arranged above the tube cooler snake, through which the cooling air heated by the tube cooler snake rises and reaches the outside. The chimney allows effective ventilation by first raising the room air warmed by the waste heat and leaving it through the chimney. Fresh, cool ambient air then flows into the cooling space via the ventilation pipe or further ventilation openings, and touches the outer wall as cooling air Pipe cooler coil over and cools the pipe wall. As a result, the cooling air cools the gas flowing through the tube cooler coil and leads to the condensation of water vapor and impurities. Conversely, the tube cooler coil heats up the air in the cold room, which thereby rises in height and passes through the chimney into the open air. Thus, a continuous, thermal, convected by waste air recirculation convection flows.

The convection can be improved by a waste heat heating is arranged in the height range above the pipe cooling coil and below or in the inlet region of the chimney or another fireplace, preferably a waste heat driven radiator or a waste heat source, such as a gas compressor. The already existing waste heat can be used here to enhance the cooling air flow in the refrigerator. This increases the cooling capacity and makes gas purification by condensation even more effective. Furthermore, the ventilation of the cold room is improved and thus reduces the risk of explosion by any penetrated biogas.

To improve the invention, it is proposed that the separator device has a condensate space with a condensate drainage pipe and a gravel bed space which is separated from the condensate space by a first separating wall which does not extend to the top of the separator device, wherein the dividing wall has openings, preferably slots or bores for the passage of Has condensate from the gravel bed room in the condensate. The freed from the condensate gas passes through the openings of the first partition in the gravel bed space, where a further purification of the gas is achieved when flowing through the gravel filling of the gravel bed.

To ensure the most intensive possible flow through the gravel bed, the gravel bed room 21 a projecting from top to bottom second partition, which does not go through to the bottom and the gravel bed room divided into two roughly equal subspaces. In this way, the gas is forced to first flow through a subspace down to the bottom area to then pass through the remaining between the second partition and the bottom gap in the second subspace, where there is the existing gravel bed from below flows through the top.

In a further embodiment of the invention, a revision cover is arranged on the upper side of the separator over the condensate space and over the two subspaces of the gravel bed space. After removing the lid, the condensate compartment and the gravel bed room can be cleaned and / or filled with new gravel.

Furthermore, the cleaning of the condensate space is facilitated by a cleaning outlet is arranged in the wall of the condensate space in the bottom area below the condensate drain pipe. The cleaning drain can be used to drain practically all of the condensate in the condensate compartment to clean the condensate compartment.

An embodiment of the invention will be explained in more detail with reference to the drawings.

The figures of the drawing show in detail:

1 : A schematic sectional view of a gas cleaning device according to the invention;

2 : a separator device in a sectional representation;

3 : the same separator in a perspective view.

In 1 you can see a part of a technical building 1 whose bottom plate 14 to form a cold room 15 partially lowered in the form of a condensate tray. In the fridge 15 is a tube cooler snake 3 arranged, whose substantially horizontally oriented turns extend helically over a height range in the order of one meter. Furthermore, is in the refrigerator 15 a separator device 4 arranged.

The uncleaned biogas / digester gas comes from the biogas plant or wastewater treatment plant via a supply line 18 and gets to the entrance end 31 the pipe cooler snake 3 , In the pipe cooler line 3 the gas cools down and the water vapor contained condenses out. The impurities, essentially hydrogen sulfide and optionally silanes or siloxanes remain in the condensate. The gas comes out of the outlet end together with the condensate 32 the pipe cooler snake 3 in the separator 4 where the condensate is separated from the gas. The cleaned clean gas comes out of the clean gas outlet 61 the separator device 4 off and passes over the gas line 6 to the gas storage 7 , In the gas storage 7 there is a gas bag 8th in which the clean gas is received. Furthermore, in the gas storage 7 a height sensor 16 arranged, which detects the height of the top of the airbag and thus allows the detection of the stored amount of gas. If the clean gas is to be supplied to a gas consumer, it again passes through the gas line 6 and a derivative 17 to a gas filter 10 and from the gas filter 10 to a gas compressor 9 where it condenses is then, with the pressure required for forwarding in through a partition 13 separated other part of the engineering building 1 to get.

The gas compressor 9 The heat generated is used in the same way as the waste heat generated in other parts of the system, in order to control the air circulation in the cold room 15 to reinforce. This is the height range between the pipe cooler snake 13 and one in the roof area of the technical building 1 arranged fireplace 2 in addition, a radiator powered by waste heat 25 arranged. Furthermore, the refrigerator is 15 with a ventilation pipe 5 equipped, whose upper end 51 flows into the open air to suck in ambient air, and its lower end 52 in the bottom area of the refrigerator 15 opens, where the sucked cooling air into the cold room 15 entry. The through the pipe cooler snake 3 and optionally by the gas compressor 9 or the radiator 25 heated room air rises through the fireplace 2 and gets out into the open. This maintains a thermal convection cooling convection that passes through the pipe cooler coil 3 stroking cooling air upwards into the chimney 2 sucks, taking over the ventilation pipe 5 always new cooling air into the cold room 15 continues to flow.

How to best in 2 recognized, there is the separator 4 from a housing which is divided into subspaces. A first partition 22 shares a condensate compartment 19 from a gravel bed room 21 from. A second partition 20 in turn divides the gravel bed room 21 in two subspaces. The arrangement of the partitions 20 . 22 you can also go in 3 recognize well. ebendso a sight glass fitting 24 in a wall of the condensate room 19 , The sight glass fitting 24 Visually controls the height of the condensate level in the condensate compartment 19 ,

The mixture of biogas / biogas and condensate passes from the outlet end 32 the pipe cooler snake 3 over an inlet 41 the separator device 4 in the condensate room 19 where the condensate is at the bottom of the condensate compartment 19 collects and the gas above the condensate through an open area between the first partition wall 22 and the top of the separator 4 in the gravel bed room 21 can transgress. The transfer of condensate from the gravel bed room 21 in the condensate room 19 is through slots, holes or other breakthroughs of the first partition 22 allows, because when flowing through the gravel bed, the gas is further purified by condensing more condensate here. To ensure the most intensive possible flow through the gravel bed is a second partition 20 provided, which is gas-impermeable and thereby forces the gas to flow over a longer distance through the gravel bed. Finally, the purified clean gas passes through the clean gas outlet 61 from the separator 4 for further use or storage.

That in the condensate room 19 Collected condensate is continuously through a condensate drain pipe 12 drained. The condensate drain pipe 12 is siphon-like bent down to the condensate in the condensate compartment 19 submerge, with the escape of gas through the condensate drain pipe 12 is prevented. In case of cleaning the separator device 4 the condensate from the condensate compartment 19 is completely in the bottom area of the condensate space 19 a cleaning outlet 11 arranged. To carry out the cleaning is the condensate compartment 19 provided on its upper side with a cleaning opening through an inspection cover 23 is closable. The two partial rooms of the gravel bed room 21 also each have an opening at the top, each with a revision cover 23 is closable. Through the openings mentioned can also be a new gravel filling in the gravel bed room 21 be filled. A suitable gravel must not contain calcareous rocks.

• – Das Faulgas wird kontinuierlich gereinigt und getrocknet, wobei durch geeignete Versuche eine ausreichende Reinigung bei entsprechender Dimensionierung verifiziert wurde.
• – Die erfindungsgemäße Reinigungsvorrichtung benötigt keine zusätzliche elektrische Energie und keine weiteren Verbrauchsmittel.
• – Die Reinigung der Rohrkühlerschlange ist während des laufenden Betriebs durch einfache Wasserspülung möglich.
• – Die Abwärme des Gasverdichters und der Faulgasverwertungsanlage (über die angeschlossene Heizung) wird nutzbringend verwertet.
• – Die Wartungskosten sind wegen der auf die Kondensat-Entnahme beschränkten Wartung sehr gering.
• – Die Explosionsgefahr und Gesundheitsgefahren sind sehr gering, denn etwa infolge eines Defektes in den Kühlraum eingedrungenes Faulgas wird durch die thermische Konvektion entfernt.

The described cleaning device and the described cleaning method have the following advantages:

• - The digester gas is continuously cleaned and dried, which has been verified by appropriate tests sufficient cleaning with appropriate dimensioning.
• - The cleaning device according to the invention requires no additional electrical energy and no other consumables.
• - Cleaning the pipe cooling coil is possible during operation by simple water flushing.
• - The waste heat of the gas compressor and the digester gas utilization plant (via the connected heating system) is utilized profitably.
• - The maintenance costs are very low because of limited to the condensate removal maintenance.
• - The risk of explosion and health hazards are very low, because, for example, as a result of a defect in the cold room penetrated fermentation gas is removed by the thermal convection.

LIST OF REFERENCE NUMBERS

1

 technology building

2

 fireplace

3

 Snake tube cooler

4

 trap structure

5

 ventilation tube

6

 gas pipe

7

 gas storage

8th

 airbag

9

 gas compressor

10

 gas filter

11

 cleaning drain

12

 Drain Pipe

13

 partition wall

14

 baseplate

15

 refrigerator

16

 height sensor

17

 derivation

18

 feed

19

 condensate chamber

20

 second partition

21

 gravel bed room

22

 first partition

23

 Access Doors

24

 Sightglass

25

 radiator

31

 entry end

32

 exit end

41

 inlet

51

 top end

52

 lower end

61

 pure gas outlet

Claims (10)

Gas purification device for the purification of biogas from a biogas plant or fermented gas from a sewage treatment plant, characterized in that a cold room ( 15 ) is provided, in which at least one tube cooler coil ( 3 ) whose entrance end ( 31 ) with a supply line ( 18 ) for the introduction of unpurified biogas / biogas, that an exit end ( 32 ) of the tube cooler snake ( 3 ) with a separator device ( 4 ), which is below the tube cooler coil ( 3 ) in the cold room ( 15 ) is arranged so that the water vapor contained in the unpurified biogas / fermentation gas with impurities in the tube cooler coil ( 3 ) condensed and the condensate in the separator device ( 4 ) is separated from thus purified biogas / biogas, which from a clean gas outlet ( 61 ) of the separator device ( 4 ) is removable. Gas cleaning device according to claim 1, characterized in that the cooling space ( 15 ) designed as a cool condensate shaft and below the ground level ( 14 ), preferably at a depth of 1.5 m or lower. Gas cleaning device according to claim 2, characterized in that the tube cooler snake ( 3 ) is configured helically or spirally with substantially horizontal turns which are located in the condensate tray ( 15 ) extend over a height range of about 1.2 m. Gas cleaning device according to one of the preceding claims, characterized in that for introducing cooling air into the cooling space ( 15 ) at least one ventilation tube ( 5 ) is provided, whose upper end ( 51 ) for the intake of ambient air in the open ends and the lower end ( 52 ) in the bottom area of the cold room ( 15 ), where the cooling air exits. Gas purification device according to one of the preceding claims, characterized in that above the tube cooler coil ( 3 ) at least one fireplace ( 2 ) is arranged, through which the of the tube cooler serpent ( 3 ) heated cooling air rises and reaches the outside. Gas cleaning device according to claim 5, characterized in that in the height range above the tube cooler coil ( 3 ) and below or in the entrance area of the fireplace ( 2 ) or another fireplace a waste heat ( 25 ) is arranged, preferably a waste heat driven radiator ( 25 ) or another waste heat source, such as a gas compressor ( 9 ). Gas cleaning device according to one of the preceding claims, characterized in that the separator device ( 4 ) a condensate space ( 19 ) with a condensate drain pipe ( 12 ) and a gravel bed room ( 21 ), which from the condensate space ( 19 ) by a not up to the top of the separator device ( 4 ) continuous first partition wall ( 22 ) is separated, wherein the partition ( 22 ) Breakthroughs, preferably slots or holes for the passage of condensate from the gravel bed space ( 21 ) into the condensate space ( 19 ) having. Gas purification device according to claim 7, characterized in that the gravel bed space ( 21 ) a projecting from top to bottom partition ( 20 ), which does not go down to the ground and the gravel bed room ( 21 ) divided into two roughly equal subspaces. Gas purification device according to claim 8, characterized in that at the top of the separator device ( 4 ) above the condensate space ( 19 ) and over the two compartments of the gravel bed room ( 21 ) one inspection cover each ( 23 ) is arranged. Gas cleaning device according to claim 9, characterized in that in the wall of the condensate space ( 19 ) in the bottom area below the condensate discharge pipe ( 12 ) a cleaning outlet ( 11 ) is arranged.

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