EP3020988A1 - Device for the production of a combustible gas mixture from a carbonaceous raw material with a shaft seal for rotary drives for wood gas technical applications - Google Patents

Abstract

The invention relates to a device for producing a combustible gas mixture from a carbonaceous starting material, in particular from chunky wood, with a feed unit (10) for supplying the starting material to a reactor (19), wherein the reactor (19) at least one oxidation zone (24) Oxidation of the starting material and a reduction zone (25) for reducing at least one intermediate product of the oxidation, wherein a shaft seal is provided for rotating drives, wherein a rotating shaft (4) against a dust, pressure and tar-loaded atmosphere with at least one sealing bushing (7) is sealed, wherein the sealing bush (7) consists of at least one split ring (3) consisting of a on the shaft (4) rotatably mounted inner ring (33) via a lubricant (38) -filled, in axial Direction directed sealing gap (34, 34a-d) with a radial outer ring (32) is in communication, in a housing (1) of the sealing book se (7) is arranged and that in the housing (1) in the axial direction of the split ring (3) removed at least one further seal (2) is arranged.

Description

The technology of wood gasification has evolved considerably in recent years, where originally the idea of gas generation for moving vehicles was in the foreground, many experts today see the future of wood gasification in the decentralized supply of energy in the form of electricity and heating heat.

To this end, the requirements for mileage and noise immunity in wood gasification plants have grown enormously. An operating life of 8000 hours per year is often required and necessary to ensure the economic operation of such a plant.

The processes for maintaining gas production therefore have to work fully automatically and maximally reliably; these include, among others, material supply, material mixing, cleaning, acquisition of parameters and many others.

Many of these processes are realized by means of rotary power driven devices including augers, flaps, scrapers, turners and other mechanical elements.

Drives of these devices are for protection against dust, tar, gas and other harmful materials and / or substances and / or relatively high temperatures, which are present inside containers of the wood gasifier, usually from outside the container by means of electric motors or other devices for the production of Rotating power driven.

This requires a nearly gas-tight seal of the shaft of the drives, which drive screw conveyors, flaps, scrapers, turners and other mechanical elements for the transmission of rotational energy, ahead.

The sealing of these shafts of the drives is made difficult by the substances and particles in the gas area inside the container relative to the environment. The gas sector includes gas, tar, dust, wood dust, encrustations, slag, pieces of wood and coal. The substances mentioned may even have particle size, which places high demands on the service life and tightness of the respective rotary feedthrough.

In particular, the existing tar reduces the life of conventional seals such as e.g. Shaft seals, O-rings, rings with circular cross section made of elastic materials, mechanical seals, stuffing boxes / stuffing boxes, packing glands, bellows mechanical seals, floating ring seals. Such seals are not useful for the intended use.

The tar adheres the known sealing elements and can harden over time. Another big problem is the abrasive material that sticks to the seal due to the tar, such as pieces of wood, dust and slag. This combination puts the sealing elements from a strong continuous wear.

The state of the art has hitherto been stuffing boxes, which in principle are already subject to wear due to their structural design. Thus, additional wear by the atmosphere in wood gasification tanks does not directly result in the failure of the gasket, but only in shortened service intervals and more frequent replacement of the gasket. The stuffing box can also be regularly filled with grease or other lubricating materials to increase mileage.

1. 1. Nachspannen der Buchsenpackung: alle 250h,
2. 2. Austauschen der Buchsenpackung: alle 4000h,
3. 3. Nachschmieren mittels Fett oder ähnlichem: alle 500h.

Maintenance intervals of stuffing boxes for sealing a shaft in a wood gasifier are approximately

1. 1. Retighten the bushing: every 250h,
2. 2. Replace the socket packing: every 4000h,
3. 3. Relubricate with grease or similar: every 500h.

Basically, it should be noted that with the stuffing box as prior art no gas-tight seal is possible. There is always a certain leakage or leakage. which should be considered critically when used in explosion-proof areas.

This leakage increases with the progress of wear of the stuffing box. Lubricated gland therefore also releases lubricant in both directions of the shaft. This grease fouls the wood gas system in the area of the shaft and the drive outside and must be cleaned regularly. Another disadvantage of the stuffing box, the size can be viewed, a seal of a 30mm shaft requires a length of stuffing box of about 10cm.

The invention is therefore based on the object, a device for generating a combustible gas mixture of a carbonaceous starting material with a shaft seal for rotary drives for wood gas applications of the type mentioned in such a way that with better sealing properties extended maintenance intervals and a more compact size can be achieved ,

To solve the problem, the invention is characterized by the technical teaching of claim 1.

In order to realize a virtually wear-free and in particular almost gas-tight sealing of rotating shafts for the transmission of rotational energy in the field of wood gasification, the seal was developed according to the invention. The rotating shafts to be sealed have a number of revolutions in the range from 1 rpm to 100 rpm. It is therefore slow-moving waves.

In essence, this seal consists of a ring or a plurality of rings with a circular cross-section of elastic materials and one or more possibly also provided with deflecting, relatively narrow Sealing gap of about 0.05-3 millimeters width between the movable and the fixed part of the seal, whereby a lubricant is introduced by the same in the opposite direction to the drive.

This lubricant may be grease, oil, soap or other carbon-based, higher-viscosity substances or the like, and protects the elastic material ring (s) from the gas area inside the wood gas plant.

The relatively narrow sealing gap can make one or more changes of direction (viewed in the axial direction in cross-section) to increase the efficiency, thereby increasing, inter alia, effectively the pressure loss coefficient. When changing direction several times, one speaks among other things of the labyrinth seal.

Therefore, the narrow gap can optionally be realized by means of a labyrinth seal, this offers the advantage of cheap and easy replacement in case of damage.

Due to the tight sealing gap, tears, dust, slags and pieces of wood are severely impeded to reach the elastic sealing ring (s). Relubrication through a bore, a groove or the like, which is located between the narrow sealing gap and the elastic sealing rings or expresses all possibly in the sealing gap or in the space to the elastic sealing ring particles, dirt, dust, tar or the like in the direction of the gas area out. There, the lubricant is continued in the flow direction of the wood gasification plant and completely burned in the reactor or engine of the plant .

The sealing of the environment against the gas area is carried out exclusively by the or nearly gas-tight rings made of elastic materials, the sealing gap and the lubricant located there are only its protection.

This method makes it possible to realize seals which are compact, inexpensive, and virtually wear-free. Tests have shown that even after more than 20,000 operating hours with regular relubrication of the sealing gap every 2500 hours, the sealing ring or rings made of elastic material had no wear.

Furthermore, this seal offers a much higher gas tightness compared to the conventional and prior art stuffing box.

1. 1. Antriebe von Förderschnecken zur Materialförderung,
2. 2. Räumer zum Bewegen und Durchmischen von Material wie Holz, Kohle oder Staub,
3. 3. Wellen zum Schließen von Klappen im Gasbereich des Holzvergasers,
4. 4. Antriebe zum Abreinigen von Filteroberflächen oder beweglichen Fühlern zur Erfassung von Füllständen.

An excerpt of the fields of application of this seal are:

1. 1. drives of screw conveyors for conveying material,
2. 2. scraper for moving and mixing material such as wood, coal or dust,
3. 3. shafts for closing flaps in the gas area of the wood gasifier,
4. 4. Drives for cleaning filter surfaces or moving sensors to detect levels.

When using elastic sealing rings made of materials with higher temperature resistance, such as silicone, PTFE, fluoroelastomers or similar materials and a temperature-resistant lubricant, the seal can withstand up to 250 ° C in continuous operation.

In a preferred embodiment of a device for wood gas applications, the seal assembly according to the invention is arranged at different points of the system.

Here, a first point relates to an area of the feed unit, namely the auger next to the gas generator, which feeds the lumpy wood material into the gas generator.

The feed screw sits in a receiving space, which is heavily acted upon by the tar-containing gas and wood dust, it acts there a pressure to about 100 mbar. Compared to this tar-charged atmosphere, now the sealing arrangement according to the invention must be arranged, which ensures a longer life.

In the application shown, the sealing arrangement is arranged in the region at the rear, front end of the screw conveyor and the associated drive motor.

In a further preferred embodiment of the present invention, a drive unit is arranged at the bottom end of the gas generator, and a drive motor is used for the rotary drive of a grate, which is designed as a rotary grate. After the drive motor is arranged at the lower end of the gas generator, temperatures in the range of 100 to 300 ° C with a corresponding pressure and a highly polluted atmosphere act there.

In a third application of the present invention, the seal assembly according to the invention is used on another component of the wood gas plant, namely on the gas generator downstream filter unit, which is connected to a Filterabreinigungsvorrichtung whose filter cleaning z. B. is designed as a vibrator and is driven in rotation by an associated geared motor, wherein the introduction of the drive shaft of the geared motor in the filter unit is in turn formed by the sealing arrangement according to the invention.

Again, there may be a tar-charged atmosphere, with a relatively high temperature of z. B. 130 ° C and a pressure of up to 100 mbar.

In a fourth embodiment, the sealing arrangement according to the invention is used in a downstream of the filter unit device which serves for the transport of separated dusts and coal pieces. Here, the seal is attached to the front end of a screw conveyor. The atmosphere is heavily polluted here.

In these applications in the field of a wood gas system, it is necessary to have a reliable sealing arrangement for the rotary feedthrough of a To achieve drive shaft of a drive motor, which ensures longer maintenance intervals with lower wear.

This is where the invention begins, which consists essentially of the combination of two different sealing arrangements.

According to the invention, a first, relative to the temperature and pressure as well as tar-loaded atmosphere resistant sealing arrangement is arranged on the housing of a sealing bush, said first sealing arrangement is formed as a split ring, which consists of a fixed outer ring which is connected via a radial gap with a rotating inner ring.

In the area between the outer ring and the inner ring of the tightly dimensioned sealing gap is arranged with a width in the range between about 0.2 to 3 mm, wherein the sealing gap either as a labyrinth sealing gap or as a zigzag or arc or as a wave sealing gap or can be formed as a straight line extending in the axial direction sealing gap.

Since the sealing gap is at least partially directed radially and at least partially in the axial direction, superior sealing properties are achieved because there are both axial and radial sealing components.

In any case, it is important that the split ring keeps the highly polluted atmosphere from the sealing arrangement located behind it in the axial direction and this is achieved in that the sealing gap on its side facing away from the dirt side is provided with a lubricant filling which penetrates and lubricates the entire sealing gap ,

Thus, a lubricant-carried seal against the tar and gas atmosphere and the underlying sealing arrangement is thereby protected against the penetration of tar and other harmful substances, especially dust and other abrasive and adhesive particles.

The lubricant has the nature of a sacrificial liquid, because the lubricant passes after passing through the sealing gap in the interior of the container and is completely burned there in the flow direction. It thus serves to lubricate the seal, but also the sealing of the sealing gap against the ingress of harmful particles and consumes itself, without causing damage during consumption. With regular relubrication, the consumption of lubricant is about 10 grams per 2500 hours.

The second, in the axial distance behind the first sealing arrangement (formed from the split ring) used sealing arrangement consists in a preferred embodiment of at least one sealing ring which forms a conical sealing lip which rests with a relatively narrow cross-section on the outer circumference of the rotating shaft and with Help of an energy storage, eg a ring spring, which rests on the outer circumference, is pressed inwardly in the radial direction on the sealing point of the shaft.

It is essential that this shaft seal is supported with the sealing lip radially outwardly by a metal sleeve, which is coated with a rubber sheath in a free space in the fixed housing part of the seal, so that the radially inwardly disposed sealing lip or sealing sleeve is supported radially by the metal sleeve.
Also known as shaft seal.

In a second embodiment of the present invention, it may be provided that the second, above-described seal assembly shaft seal with the sealing lip and the metal sleeve is replaced by a simple O-ring.

It can also be used several consecutive O-rings.

Instead of using an O-ring, other combinations of O-rings and gaskets can be used. Here are meant above all elastic rings with circular cross section.

At an axial distance, the seal can abut against a retaining ring or retaining ring to achieve an axial support.

It is important that it is provided that the shaft to be sealed is cantilevered, d. H. There are no axial forces transmitted via the shaft to the seal after the invention is provided that the actual shaft bearing in the drive gear of the rotary drive itself is made.

If the shaft is not secured in the geared motor itself against radial and axial displacement forces, it may be provided in a further embodiment, to arrange the actual shaft bearing behind the sealing bush according to the invention outside of the container.

In any case, it is important for the invention that the sealing bush according to the invention, which consists of the combination of at least two axially spaced-apart sealing arrangements, is always arranged next to the harmful atmosphere.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Figur 1:

schematisierte Ansicht einer Anlage zur Erzeugung von brennbarem Gas aus einem kohlenstoffhaltigen stückigen Verbrennungsgut

Figur 2:

ein schematisierter Längsschnitt durch eine erfindungsgemäße Wellen-Abdichtung

Figur 3a:

eine erste Ausführungsform einer abgewandelten Form des Spaltrings

Figur 3b:

eine zweite Ausführungsform einer abgewandelten Form des Spaltrings

Figur 3c:

eine dritte Ausführungsform einer abgewandelten Dichtungsanordnung der Spaltringes

Figur 3d:

eine vierte Ausführungsform der Formgestaltung des Spaltringes mit seinem Dichtungsspalt

Show it:

FIG. 1:

Schematic view of a plant for the production of combustible gas from a carbonaceous lumpy combustion material

FIG. 2:

a schematic longitudinal section through a shaft seal according to the invention

FIG. 3a:

a first embodiment of a modified form of the split ring

FIG. 3b:

a second embodiment of a modified form of the split ring

FIG. 3c:

a third embodiment of a modified seal arrangement of the split ring

Figure 3d:

a fourth embodiment of the design of the split ring with its sealing gap

In FIG. 1 3 is a schematic diagram of a plant for the production of combustible gas, which consists essentially of a feed unit 10 which supplies the carbonaceous material to be burned in the direction of arrow 12 to a screw conveyor 11 which feeds the material via a vertical drop section 13 via an open closure element 14 in a buffer 15 promotes.
The closure element 14 is only temporarily opened and is intended to prevent the gas generated in the gas generator 19 from escaping from the feed unit 10 to the rear.

The carbonaceous material to be burned is stored batchwise in the intermediate storage device 15 and is supplied to the inlet side of a gas generator 19 in the direction of arrow 18 as required via a rotary driven screw conveyor 17 which is arranged in a receiving space 8.

It is now important that the screw conveyor 17 is driven by a geared motor 16, whose drive shaft 4 passed through a sealing bushing 7 is, which corresponds to the invention. Beyond the sealing bush 7, an intermediate flange 6 is arranged.

In the gas generator 19, the material is gasified in the region of an ember bed 23, wherein combustion air is introduced in the direction of arrow 22 via lateral air inlets 20, 21. Accordingly, the ember bed 23 is subdivided into an upper area, which is referred to as the oxidation zone 24 and into a lower area, which is referred to as the reduction zone 25.

The further sealing bush 7 according to the invention is arranged in the bottom region of the gas generator 19 and drives, for example, a grate 55, which is designed as a rotary grate. The drive shaft shown there is rotatably coupled to the gear motor 16.

The gas generated in the gas generator 19 is passed through a gas outlet 26 and a gas line 27 in a downstream filter unit 28 in which one or more filters 54 are arranged.

The filters 54 can be cleaned by a filter cleaning 53, which is formed in the embodiment shown as a vibrator, which is rotationally driven by a geared motor 16, wherein the implementation of the drive shaft in the filter unit 28 in turn via the sealing bush 7 according to the invention.

From the embodiment shown it follows that the sealing bushing 7 according to the invention is exposed in each case at the indicated locations of a tar-containing and dust-laden atmosphere and can withstand high temperatures.

For the reasons mentioned, the invention proposes a sealing bushing 7 according to a preferred embodiment FIG. 2 in front.

In FIG. 2 is the rotationally driven drive shaft 4, wherein it is again emphasized that the sealing bushing 7 preferably to the in FIG. 1 shown applications can be used. However, other applications can be provided, which in the schematic drawing FIG. 1 are not shown.

The rotationally driven shaft 4 can be driven both in the direction of arrow 9 counterclockwise or clockwise.

In the FIG. 2 shown sealing bushing 7 is used as an application in connection with the drive of the screw conveyor 17 in FIG. 1 explained.

The tar- and dust-laden atmosphere is given in the receiving space 8 and the dirt attack is carried out in the direction of arrow 39 on the front side of a housing 1 of the sealing bushing 7, wherein on this end face of the split ring 3 is arranged to reject the first dirt attack.

The split ring 3 according to the invention consists of a non-rotatably connected to the housing 1 outer ring 32 and an inner ring 33, wherein a gap between the two rings 32, 33 is formed by a sealing gap 34.

In the illustrated embodiment, the sealing gap 34 consists of an approximately zig-zag-shaped shape, so that thus straight and short sections 35, 36 each connect to each other in a turning point 37 at an angle and so directed in the axial direction, zigzag-shaped Seal gap 34 result.

This special design of the sealing gap 34 prevents harmful material from being forced under pressure from the dirt and dust-laden atmosphere in the direction of arrow 39 through the sealing gap 34.

At the opposite end of the split ring 3, an annular space 31 is arranged, which is preferably filled with a highly viscous lubricant 38. The type and composition of the lubricant 38 has already been mentioned in the general description.

It is important that the annular space 31 is fluid-conductively connected to a bore 5 through which the highly viscous lubricant is introduced.

After the introduction of the lubricant, which takes place under pressure, the bore 5 is closed again.

In a preferred embodiment of the invention, it is provided that the annular space 31 is located next to the seal arrangement, which is designed as a shaft seal 2.

In another embodiment, however, it may be provided that a separation is present, so that the lubricant in the annular space 31 can not get into the underlying shaft seal 2.
The shaft seal 2 here consists of a radially outer metal sleeve 50, which is vulcanized in a rubber jacket or in another elastic material. It is merely indicated for the sake of simplicity that the elastic material is formed as a rubber sleeve 43. Instead of a rubber sleeve, any other elastic material can be used.

The metal sleeve 50 consists of a first leg aligned in the axial direction, which merges into a further leg (radial shoulder 52) deflected in the radial direction.

The radial approach 52 engages in an associated, radially outwardly open annular groove 49 and thus supports the multi-angled sealing lip 48 from.

The sealing lip 48 is conically shaped in section and forms an elastomeric sleeve which rests only with a (in the sectional view) oblique and relatively acute-angled portion in the region of a sealing point 46 on the peripheral circumference of the drive shaft 4 sealingly and positively and positively.

The radial pressure force is achieved by an annular spring 47, which generates a spring-loaded biasing force in the radial direction on the sealing lip 48. The rubber-coated metal sleeve 50 and the sealing lip 48 are supported in the axial direction on a Gegenhaltering 40, which in turn rests against a securing ring 41 secured against axial displacement.

The centering ring 42 may be part of the geared motor and center the housing 1 of the sealing bushing 7 in the direction of the geared motor.

In the Figures 3a-3d Various embodiments for the formation of a sealing gap are shown in more detail.

In the embodiment according to FIG. 3a the sealing gap 34a is formed as a symmetrically shaped shaft.

In the embodiment according to FIG. 3b the sealing gap 34b is formed as a straight, continuous axial gap, wherein it is crucial that the axial length of the sealing gap 34b is substantially longer than the column width. It is here - in all other examples - ratios in the range of 1:50 in the gap length compared to the gap width preferred.

In Figure 3c is shown as a further embodiment, a sealing gap 34c as a bow, while in the 3d figure the sealing gap 34d shown there consists of several, each at an angle of 90 degrees adjoining lines.

The invention may also recite the combinations of various sealing gaps from one or more shapes FIG. 2 or one or more shapes Figures 3 to 3d include.

It is therefore important in the present invention that, in a thermally stressed, dust and tar-loaded environment, the sealing arrangement is first protected by a split ring exposed next to this attack atmosphere, which is supplied with a highly viscous lubricant and that in the axial direction behind the gap ring, a shaft seal connects, which is supplied with the same lubricant.

drawing Legend

1

casing

2

Shaft seal

3

split ring

4

drive shaft

5

drilling

6

Wafer

7

packing sleeve

8th

Recording room (for 17)

9

arrow

10

feed

11

Auger

12

arrow

13

case section

14

closure element

15

cache

16

gearmotor

17

Auger

18

arrow

19

gas generator

20

air introduction

21

air introduction

22

arrow

23

fire bed

24

oxidation zone

25

reduction zone

26

gas outlet

27

gas pipe

28

filter unit

29

Gas outlet (from 28)

30

arrow

31

annulus

32

outer ring

33

inner ring

34

seal gap

35

section

36

section

37

turning point

38

lubricant

39

Arrow direction (tar effect)

40

Pressure ring

41

circlip

42

centering

43

rubber sleeve

44

45

46

sealing point

47

Ringfeder

48

sealing lip

49

ring groove

50

metal sleeve

51

52

radial approach

53

Filter cleaning

54

filter

55

rust

Claims (10)

Apparatus for producing a combustible gas mixture from a carbonaceous starting material, in particular from chunky wood, with a feed unit (10) for supplying the starting material to a reactor (19), wherein the reactor (19) at least one oxidation zone (24) for the oxidation of the starting material and a reduction zone (25) for reducing at least one intermediate product of the oxidation, wherein a shaft seal is provided for rotating drives and wherein a rotating shaft (4) against a dust, pressure and tar-loaded atmosphere with at least one sealing bushing (7) sealed is, characterized in that the sealing bush (7) consists of at least one split ring (3) consisting of an on the shaft (4) rotatably mounted inner ring (33) via a lubricant (38) -filled, in the axial direction directed sealing gap (34, 34a-d) with a radial outer ring (32) communicating in a housing (1) of the sealing bushing (7) is arranged and that in the housing (1) in the axial direction of the split ring (3) removed at least one further seal (2) is arranged. Apparatus according to claim 1, characterized in that the split ring (3) is arranged next to the dust, pressure and tar-loaded atmosphere and is acted upon with its one end face of this and that the further seal (2) at an axial distance from the split ring ( 3) in the direction of its other end face in the housing (1) is arranged. Apparatus according to claim 1 or 2, characterized in that the sealing gap (34) of the split ring (3) is zig-zag or wavy or rectilinear or arcuate or labyrinth-shaped and has a width in the range between 0.05 to 3 millimeters , Device according to one of claims 1 to 3, characterized in that the ratio of the length of the sealing gap (34) to its width is about 50: 1. Device according to one of claims 1 to 4, characterized in that the further seal (2) is lubricated by the lubricant (38). Device according to one of claims 1 to 5, characterized in that the lubricant (38) is introduced under pressure relative to the attacking atmosphere of an annular space (31) of the housing (1) and the axial passage through the sealing gap (34, 34a-d ) of the split ring (3) enters the attacking atmosphere. Device according to one of claims 1 to 6, characterized in that the sealing ring (2) consists of an elastic, temperature and abrasion resistant plastic material. Device according to one of claims 1 to 7, characterized in that the further seal consists of a shaft sealing ring (2) which rests positively and positively on the outer circumference of the shaft (4) with a radially spring-loaded sealing lip (48). Apparatus according to claim 8, characterized in that the shaft to be sealed (4) cantilevered into the housing (1) of the sealing bush (7) engages. Device according to one of claims 1 to 9, characterized in that as a shaft seal (2) formed further seal has a rubber-coated metal sleeve (50) and that the sealing lip (48) of the shaft seal (2) in the axial direction on a Gegenhaltering (40 ), which in turn rests against a securing ring (48) secured against axial displacement, wherein the securing ring (41) is supported on the outside of a centering ring 42.

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