EP2336276B1 - Gas cooler with knocking device - Google Patents

Description

The invention relates to a gas cooler for cooling synthesis gas, which is obtained by gasification, with a gas guide tube, which is flowed through for the purpose of cooling synthesis gas. The gas is preferably combustible and can be supplied for thermal utilization. It can be burned after cooling and subsequent filtration or cleaning, for example, for power generation or for heating purposes.

The patent EP 1 112 970 B1 discloses a plant and a process for the production of combustible gas, especially from sewage sludge. The sewage sludge is preferably introduced dried into a gasifier and there thermally decomposed by heating under air deficiency, ie gasified thereby obtaining a combustible gas or gas mixture. However, there is the problem that pollutants are contained in the synthesis gas thus obtained, especially tar. The tar has the property that it condenses on cooling and precipitates in the gasifier downstream piping and equipment. For the deposition of the tar, the aforementioned patent proposes to cool the synthesis gas obtained by the gasification of sewage sludge and then to pass it through the sewage sludge as a filter, which serves as the starting material for the gasification. When passing the Synthesis gas through the sewage sludge, the tar contained in the recovered gas settles in the sewage sludge, the tar is filtered out of the synthesis gas. Condition for the filtering is that the tar is condensed by cooling the synthesis gas. Together with the sewage sludge, the filtered tar is fed to the gasifier where it is gasified, in particular converted into a combustible gas.

The synthesis gas obtained in the gasification has a temperature of significantly more than 1,000 ° C at the outlet from the gasifier, which is lowered by a subsequent special precooler (recuperator), for example, up to about 650 ° C. At this temperature, the tar is exclusively in the gaseous state. After the recuperator, the synthesis gas is fed to a gas cooler with a downstream sewage sludge filter for further cooling. In a gas guide tube of the gas cooler, the temperature of the synthesis gas is further reduced to about 120 ° C. At this temperature of the synthesis gas, the tar condenses, so that it is subsequently filtered out when passing through the sewage sludge. However, there is still no condensation of water vapor.

The synthesis gas entering at a gas inlet into the gas guide tube of the gas cooler is loaded, apart from tar, with small solid particles which settle in the gas guide tube together with part of the tar during the cooling of the synthesis gas, for example by quenching. By flushing water into the gas guide tube, the synthesis gas can quench, so cool the gas to a desired temperature. During quenching, the solid or condensing constituents of the synthesis gas deposit in a layered form, above all in a region of the gas guiding tube which is near the gas inlet. The layer fouls the gas guide tube and, as a rule, must be removed after several weeks, for example every six weeks, when the gas cooler is in operation. The removal of the layer is both time and labor consuming, on the other hand, the system for except Operation. This reduces the degree of utilization of the system, as no gas can be processed during downtime.

The patent DE 37 25 424 C1 discloses a gas cooler with a boiler, in the cooled to be cooled, laden with dust gas from below and flows out the top. In the boiler radiant heating surfaces are arranged, which are designed as a pipe-web-tube construction. It is a Strahlungsheizfläche tubular and there are more Strahlungsheizflächen arranged radially in the boiler.

The international patent application WO 2009/030 674 A2 discloses a gas cooler with an outer tube and an inner tube through which gas to be cooled flows. The inner tube widens conically in its center and is rigidly attached to the outer tube at a lower, larger diameter edge. An upper end of the inner tube is also rigidly mounted in the outer tube or rigidly connected to a feed tube, which opens obliquely from below into an upper, smaller diameter portion of the inner tube. In the conically widening section of the inner tube protrude star-shaped injection tubes with downwardly directed injection nozzles. In a lower portion of a lower, larger diameter portion of the inner tube near a discharge end knockers are arranged to rid the inner tube of adhesions.

Based on the above-described prior art, the invention is based on the object to improve an efficiency of the cleaning of the gas cooler by knocking.

This object is achieved by a gas cooler with the features of claim 1. Further advantageous embodiments can be found in the dependent claims.

In the gas cooler for cooling synthesis gas of the present invention, a knocking device having a knocker for transferring knocking energy is disposed on the gas guide pipe in which the synthesis gas is cooled. The knocker, which is attached to an outside of the gas guide tube, for example be operated mechanically, electrically, pneumatically or hydraulically. It allows a continuous or at any time intervals periodic removal of components that settle when cooling the synthesis gas in the gas guide tube as impurities in particular as a solid layer. To remove the layer, the gas cooler does not need to be taken out of service.

The synthesis gas passed through the gas cooler is produced, in particular, by the gasification of non-fossil energy sources, the gas cooler having a foot region and a head region arranged higher in relation to the foot region, between which the gas guidance tube extends. The gas guide tube is flowed through by the synthesis gas from the head region to the foot region or in the reverse direction. It has proved to be advantageous to provide a gas inlet at the head region and a gas outlet at the foot region, so that the synthesis gas flows in the gas guide tube from top to bottom. When knocking falling particles fall by gravity down into the foot of the radiator, from which they are easily removed. Preferably, the particles fall into the sewage sludge or the substance to be gasified and are supplied with it to the gasification.

The gas guide tube has an oscillating trained and vibrationally received inner tube, wherein the synthesis gas flows substantially through the inner tube. The synthesis gas is cooled only in the inner tube of the gas cooler, so that deposits mainly arise only on an inner side of the inner tube. The knocking energy from the knocking device is transferred to the inner tube. The inner tube is expediently made of a thinner wall than the load-bearing and pressure-resistant gas guide tube. It is compared to the thicker walled gas guide tube, which forms a supporting element of the gas cooler and thus can be made to vibrate hardly or only by transmitting very high knocking energy, far less capable of vibration and vibrating with the foot, the head area or the gas guide tube connected to the gas cooler. The connection is only from a portion of the inner tube, so that the other sections are not clamped, but can swing freely. In contrast, the gas guide tube is rigidly connected by its two ends to the head and the foot, which greatly limits the ability of the gas guide tube to vibrate.

The inner tube can thereby be excited with significantly less knocking energy to vibrate and thus to release the layer, as the gas guide tube. The oscillatory inner tube can also absorb more knock energy and convert it into vibrational energy than the outer gas guide tube. This supports the cleaning effect of the knocker of the knocking device. The inner tube is attached only at one end to the gas guide tube, at the head or at the foot of the gas cooler. In this way, the inner tube can absorb very well knocking energy to replace the deposits. This can be realized particularly easily if the gas guide tube extends vertically, for example by the inner tube is hung with a chain or chains in the head area of the gas cooler.

The inner tube allows thermal insulation of the gas guide tube without vibration damping of the inner tube.

In a preferred embodiment of the invention, the knocker of the knocking device acts on the inner tube carrying the majority of the synthesis gas. This intermittent outgoing shock pulses are transmitted by the knocker particularly effective as knocking energy to the inner tube. It is particularly favorable when the gas guide tube has a passage for a tappet of the tapping device, which is actuated by the tappet, wherein the tapping device is made gas-tight and connected in a gastight manner to the gas guide tube. This is necessary because the synthesis gas flowing through the gas guide tube or through the inner tube arranged in the gas guide tube would have an overpressure of typically 300 mbar and would escape in the event of a leakage of the gas guide tube. Due to the high temperature of the gas, which is between 650 and 130 ° C, the combustible synthesis gas would ignite immediately on contact with the atmospheric oxygen at the exit point.

It has proven to be advantageous that the plunger of the knocking device bears in a basic position on the inner tube and that the knocking device has a metallic bellows (corrugated tube) as a spring element for the knocker or for the plunger of the knocking device. As a result, the inner tube without delay and loss of knocking energy is applied directly to the outgoing from the knocker shock pulses, the plunger or the knocker returns by the spring element after each shock to its normal position. By the spring element is designed as a bellows, it simultaneously assumes the seal between the knocker or the plunger of the knocking device and the gas guide tube.

In one embodiment of the gas cooler according to the invention is in the head region, for example, a funnel-shaped or a disc-shaped Guiding element arranged for the synthesis gas, which covers an annular space between the gas guide tube and the inner tube. The guide element covers the gap between the inner tube and the gas guide tube, without sealing it. Thus, the guide element does not hinder the inner tube in its ability to vibrate. Only a small volume fraction of the synthesis gas flowing through the gas cooler flows past the inner tube on the outside. The predominant volume fraction of the synthesis gas to be cooled is directed by the guide element into the inner tube. When the synthesis gas is cooled, condensates from the synthesis gas and solid suspended matter particles entrained in the synthesis gas are deposited on the inside of the inner tube as a deposit layer. The deposits decrease with increasing distance from the inflow end. Since the knocking device preferably acts on the inner tube and thereby transfer the entire knocking energy essentially as vibration energy to the inner tube, the deposits occurring there can be removed particularly effectively.

In an advantageous embodiment of the invention, a quench device for cooling the synthesis gas and promoting condensate formation is arranged in the head region of the gas cooler. Many chemical pressurized processes involving hot gases or hot gas mixtures involve a step of rapidly cooling the gas or gas mixture with partial or complete condensation. Such a step of rapid cooling is commonly called "quenching". During quenching, in general, the hot gas or gas mixture, in the gas cooler according to the invention, the synthesis gas flowing through the gas cooler, is brought into contact with a comparatively large amount of a cooling medium and at least partially condensed. As a cooling medium, in particular a water spray can be used, which is sprayed from the head of the gas cooler in the inner tube. The spray evaporates and removes heat from the syngas. The synthesis gas cools down. Depending on the achieved temperature of the synthesis gas, gaseous constituents entrained by the synthesis gas condense. The condensed constituents and / or the water vapor bind the solid particles contained in the synthesis gas and settle at least partially inside the inner tube.

It has proven expedient to connect a cyclone separator to a gas inlet of the gas cooler for the synthesis gas, which is preferably arranged in the head region of the gas cooler. With the cyclone separator solid particles of a certain size and / or mass are separated from the gas by a centrifugal force acting on the synthesis gas before entering the gas cooler. After the cyclone separator, the synthesis gas usually only has fine solid particles. The synthesis gas is pre-cleaned, so that the gas cooler is less contaminated during cooling of the synthesis gas and thus in particular less deposits on the gas guide tube or on the inner tube occur. This increases especially the time intervals between necessary cleanings in which deposits are removed from the inner tube by means of the knocking device.

The gas cooler according to the invention preferably has a filter arranged in the flow direction of the synthesis gas after the gas guide tube or the inner tube, the filter material of which is the starting material to be gasified. In a gas inlet arranged at the head region of the gas cooler, the filter is accommodated in the foot region. For thermal utilization, predominantly non-fossil raw materials which can be gasified into the synthesis gas in a gasifier are provided, in particular renewable raw materials or biofuels. Preferably, sewage sludge is selected as the starting material. The filter material of the filter consists of these regenerative and gasified starting materials.

To cool the synthesis gas with the gas cooler water is injected through one or more water nozzles in the gas guide tube or the inner tube.

Preferably, the inner tube of the gas cooler ends before the filter, so that the vibration capacity of the inner tube is not limited by the filter.

Depending on the length of the gas guide tube or of the inner tube, it may be expedient to arrange two knocking devices at a different distance from the head and foot region on the gas guide tube. Since significantly more deposits are formed near the gas inlet on the gas guide tube or the inner tube when the synthesis gas is cooled than it is farther away, it is advantageous to apply a first knocker to a cooling region of the gas cooler close to the gas inlet and a second knocker onto the cooling region farther away from the gas inlet to act.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. Further features of the invention will become apparent from the following description of the embodiment of the invention in conjunction with the claims and the accompanying drawings. The individual features of the invention may be implemented on their own or in several different embodiments of the invention.

Figur 1

einen erfindungsgemäßen Gaskühler in Längsschnittdarstellung;

Figur 2

ein eingangsseitiges Ende eines Gasführungsrohres mit Innenrohr und Klopfvorrichtung des Gaskühlers gemäß Figur 1, in vergrößerter Darstellung;

Figur 3

die Klopfvorrichtung aus Figur 1 in Detailansicht; und

Figur 4

einen Kopfbereich des Gaskühlers gemäß Figur 1 mit einer Quencheinrichtung.

In a schematic representation:

FIG. 1

a gas cooler according to the invention in longitudinal section;

FIG. 2

an input-side end of a gas guide tube with inner tube and knocking device of the gas cooler according to FIG. 1 in an enlarged view;

FIG. 3

the knocking device off FIG. 1 in detail view; and

FIG. 4

a head portion of the gas cooler according to FIG. 1 with a quenching device.

FIG. 1 shows a gas cooler 1 according to the invention for the cooling of synthesis gas, which is obtained by gasification of a regenerative starting material. The gas cooler 1 has a head region 2 and a foot region 3, between which a gas guide tube 4 is arranged. In the gas guide tube 4 is a oscillatory inner tube 5 suspended vibratory. The head region 2 has a gas inlet 6 and the foot region 3 has a gas outlet 7 for the synthesis gas. In the flow direction downstream of the inner tube 5, a filter 8 is arranged from the starting material provided for the gasification, through which the cooled synthesis gas passes before it reaches the gas outlet 7. The gas guide tube 4 extends vertically between the head portion 2 and the foot portion 3 of the gas cooler 1, wherein the inner tube 5 is concentrically received by the gas guide tube 4 and ends before the filter 8. The gas guide tube 4 has a knocking device 9 for transmitting knocking energy to the inner tube 5, can be solved by means of solid deposits, not shown in the drawing from an inner side 10 of the inner tube 5. The filter 8 is filled to about the funnel, which covers the filter 8 and carries the gas guide tube 4, filled with filter material. The filter material is sufficient in any case to over the Gausauslass 7. The filter material is dried sewage sludge or other substance to be gasified.

The head region 2 has, in extension of the inner tube 5, a quench device 11 which cools the synthesis gas by adding water in the inner tube 5. The water is sprayed vertically into the inner tube 5 and evaporated in the inner tube 5, wherein the water vapor dissolves in the synthesis gas.

The gasification of the regenerative starting material takes place in a carburettor, not shown, from which the synthesis gas exits and a gas inlet 6 of the gas cooler 1 upstream cyclone is supplied before it enters the gas cooler 1. The carburetor and the cyclone separator are not shown in the drawing. As a starting material for the gasification preferably dried sewage sludge is used, which is also used as a filter 8 in the foot region 3 of the gas cooler 1 and dried by the passed through synthesis gas.

An outer diameter of the inner tube 5 is smaller compared to an inner diameter of the gas guide tube 4, so that in concentric arrangement of the inner tube 5 and the gas guide tube 4 results in an annular space 12 between them. Above, so at the gas inlet, the gap 12 is covered by a funnel-shaped guide element 13, which does not seal the gap 12. The synthesis gas thus flows essentially through the inner tube 5, which is acted upon by the knocking device 9 during a cleaning process. In the inner tube 5, water for cooling the synthesis gas is sprayed by one or more, not shown in the drawing, the quench 11 associated with water nozzles.

The synthesis gas to be cooled flows at a typical temperature of, for example, about 600 ° C. through the gas inlet 6 into the head region 2 of the gas cooler 1 and is guided from there into the inner tube 5. When flowing through the inner tube 5, the temperature of the synthesis gas is lowered to reach the filter 8 to a characteristic temperature of about 120 ° C. The temperature is controlled by the amount of water injected. In the gas contained solid particles form with the condensed tar a sticky mass, which settles above all in an upper, near the head region 2 near the inner tube 5 as a layer. The resulting layer must be removed from time to time, for example after a few weeks of operation of the gas cooler 1 by means of the knocking device 9. At a temperature above 120 ° C, the water sprayed into the synthesis gas and the tar dissolved in the synthesis gas, wherein the tar contained in the gas condenses in the further cooling to 120 ° C to Teertröpfchen in the preferably consisting of dried sewage sludge filter. 8 be filtered out when passing.

The sprayed into the inner tube 5 for cooling the synthesis gas water occurs in the synthesis gas dissolved from the gas outlet 7 from the foot portion 3 of the gas cooler 1 after it has passed the filter 8. When passing the synthesis gas through the sewage sludge in the filter 8, the synthesis gas additionally absorbs water which is contained in the sewage sludge of the filter 8 as moisture. The synthesis gas obtained by the gasification dries the Sewage sludge after cooling in the inner tube 5 when passing through the filter 8. After the gas outlet 7, the synthesis gas can be fed to a not shown in the drawing capacitor for moisture removal, which at least partially removes the water from the synthesis gas.

FIG. 2 shows the transition from the head portion 2 to the gas guide tube 4 with inner tube 5 in an enlarged detail with a different viewing direction than FIG. 1 , In this view, a second knocking device 9 'is visible, which can act on the inner tube 5 with a plunger 14 with knocking energy. The inner tube 5 is provided with three retaining chains 15, of which in FIG. 2 only one is visible, suspended in the gas guide tube 4. For this purpose, the gas guide tube 4 hooks 16 and the inner tube 5 oppositely arranged support hooks 17 for attaching the retaining chains 15. The inner tube 5 is formed thin-walled relative to the surrounding sustainable gas guide tube 4. This assists the propagation of vibrational energy from the knocking device 9 '. The FIG. 2 also shows the guide element 13 for the synthesis gas, which in the FIG. 4 shown again in a different perspective. The knocking device 9 'close to the head region 2 corresponds in structure and in the mode of operation in the following FIG. 3 shown, the foot area 3 obvious knocking 9th

The FIG. 3 shows the knocking device 9 from FIG. 1 enlarged, which has a knocker 18 which acts on the plunger 14. The knocking device 9 is gas-tight and connected in a gastight manner with the gas guide tube 4. The gas guide tube 4 has a passage 19 for the plunger 14, from which the plunger 14 extends from the knocker 18 to the inner tube 5. The plunger 14 is in a basic position, as shown in the FIG. 3 is shown, on the inner tube 5, wherein a baffle plate 20 is disposed opposite the plunger 14 on the inner tube 5. The baffle plate 20 permanently prevents damage to the inner tube 5 by the plunger 14. The knocker 18 is pneumatically operated in the embodiment, wherein another, for example hydraulic, electrical or mechanical drive not is excluded. From the gas guide tube 4 is a mounting tube 21 for the knocker 18 is radially from where the knocking device 9 is attached. The knocking device 9 has between the knocker 18 and the mounting tube 21 designed as a spring element metallic bellows 22 (corrugated tube) on the one hand seals the knocker 18 relative to the mounting tube 21 and on the other hand acts on the plunger 14 with spring force, so that this in a basic position on Inner tube 5 is present.

In FIG. 4 is the transition from the head portion 2 to the gas guide tube 4 and the inner tube 5 as an enlarged section of the FIG. 1 displayed. The gas inlet 6 provided on the head region 2 extends perpendicularly to the gas guide tube 4 with the inner tube 5 and to the quench device 11 arranged concentrically with the tubes 4, 5. The tapping device 9 'can also be seen. The transition from the head region 2 to the gas guide tube 5 forms the guide element 13, which is placed on top of the viable gas guide tube 4 at the top and carries the head region 2 of the gas cooler 1. The guide element 13 is frontally connected to the gas guide tube 4 and the head portion 2 gas-tight, in particular screwed.

The funnel-shaped guide element 13 covers the inner tube 5 at the end with an axial distance, so that the synthesis gas to be cooled flows substantially inwardly through the inner tube 5. The guide element 13, which engages over the intermediate space 12 between the gas guide tube 4 and the inner tube 5, also has a number of radially inwardly extending baffles 23. The baffles 23 avoid swirling when the synthesis gas enters the inner tube 5.

Claims (6)

1. A gas cooler (1) for cooling synthesis gas, which is produced by gasification, with a gas guide pipe (4), through which synthesis gas flows, with an inner pipe (5) which is constructed to be capable of oscillation and is fastened in the gas guide pipe (4), wherein the synthesis gas flows substantially through the inner pipe (5), and with a knocking device (9, 9'), which is arranged at the gas guide pipe (4) and which has a knocker (18) which acts on the inner pipe (5), characterised in that the inner pipe (5) is fastened at only one end in the gas guide pipe (4) and that the inner pipe (5) is connected to the gas guide pipe (4) so as to be capable of oscillation.
2. A gas cooler as claimed in claim 1, characterised in that the gas guide pipe (4) includes a passage (19) for a push rod (14) of the knocking device (9, 9'), which operates the knocker (18), wherein the knocking device (9, 9') is of gas-tight construction and is connected to the gas guide pipe (4) in a gas-tight manner.
3. A gas cooler as claimed in claim 2, characterised in that the push rod (14) of the knocking device (9, 9') touches the inner pipe (5) in an initial position.
4. A gas cooler as claimed in claim 2 or 3, characterised in that the knocking device (9, 9') includes a gaiter as a spring element for the knocker (18) or the push rod (14) of the knocking device (9, 9').
5. A gas cooler as claimed in one of the preceding claims, characterised in that a guide element (13) for the synthesis gas is arranged at a junction from the head region (2) to the gas guide pipe (4),which covers an annular gap (12) between the gas guide pipe (4) and the inner pipe (5).
6. A gas cooler as claimed in one of the preceding claims, characterised in that a quenching device (11) for cooling the synthesis gas and for promoting the formation of condensate is arranged in the head region (2)

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