WO2003012014A2

WO2003012014A2 - Device and method for the generation of gas

Info

Publication number: WO2003012014A2
Application number: PCT/DE2002/002242
Authority: WO
Inventors: Hubertus Winkler; Rolf Schmitt; Harald Hensler; Helmut WÖRZ
Original assignee: Bu Bioenergie & Umwelttechnik Ag
Priority date: 2001-07-20
Filing date: 2002-06-19
Publication date: 2003-02-13
Also published as: WO2003012014A3; EP1485448A2

Abstract

The invention relates to a device for the generation of gas (10), in particular of hydrogen-rich synthesis gas from biogenic or other carbonaceous material (9), whereby the material (9) is allothermically vaporised in a reactor (1) with the formation of a fluidised bed (2) and said fluidised bed (2) is heated. According to the invention, an economical and effective generation of gas may be achieved, whereby said device is characterised in that, in the region of the fluidised bed (2), heating tubes (3) at least partly extend through the fluidised bed (2). The invention further relates to a method for the generation of gas (10), in particular of hydrogen-rich synthesis gas from biogenic or other carbonaceous material (9), whereby the material (9) is allothermically vaporised in a reactor (1) with the formation of a fluidised bed (2) and said fluidised bed (2) is heated, by using heating tubes (3) at least partly extending through the fluidised bed (2).

Description

"Device and a method for generating gas"

The invention relates to a device and a method for generating gas, in particular hydrogen-rich synthesis gas from biogenic or other carbon-containing material, the material being gasified allothermally in a reactor to produce a fluidized bed and the fluidized bed being heated.

Devices and methods of the type in question are already known from practice. Biogenic substances such as biomass, organic waste, sewage sludge or liquid manure, animal waste and other carbon-containing compounds are gasified using different processes and devices.

So-called autothermal and allothermal gasifications are known as essential processes. Autothermal heating means direct heating of the material to be gasified, for example by combustion with air or oxygen. Autothermal systems are mainly implemented for small, decentralized applications and can only be used to a very limited extent with regard to downstream work machines due to the tar produced during the gasification reaction and the low calorific value of the gas generated. Gas engines can be significantly damaged by the tar in the gas produced.

In allothermal gasification processes, the material to be gasified is indirectly heated by external heat. For example, it is conceivable to heat the walls of a reactor and thus transfer the heat to the material to be gasified.

Against this background, water vapor gasification in a fluidized bed reactor supplies medium to high calorific gases with a high hydrogen content. Because of its essential components, which include hydrogen, methane, carbon monoxide and carbon dioxide, gas generated from biogenic substances corresponds to the syngas known in the chemical and petrochemical industry. This gas offers great advantages in terms of energy use, since it has a very low tar content but a high hydrogen content having. In gas engines, gas turbines and high-temperature fuel cells, a gas of this composition can be used particularly well to generate electrical and thermal energy.

In order to generate such a high-energy gas, heat has to be introduced into the gasification reactor during endothermic gasification reactions without causing a dilution of the gas to be generated. For this purpose, two fundamentally different procedures are known from practice:

In the gasification reactor, the heat can be introduced into the material to be gasified by circulating hot bed material. The bed material is heated externally to high temperatures.

The second known method for introducing the required heat of reaction uses heating surfaces which are integrated into the fluidized bed of a fluidized bed reactor.

However, these known technologies and devices which are used in allothermal gasification processes in fluidized bed reactors are disadvantageous in many respects.

The external heating of bed material can result in high heat losses, so that complex insulation measures are necessary to prevent heat loss. With the other known technology, which aims to integrate heating surfaces into the fluidized bed, geometrically complicated, extensive heating surfaces often have to be formed in order to realize a large heat exchange surface and an effective heat transfer. Because of these requirements for the heating surfaces, they have to be manufactured in a complex manner and often represent a considerable flow resistance in the fluidized bed. In addition, it is disadvantageous that the heating surfaces are often heated by external energy sources, for example electrically, and in this case large energy losses due to resistances, Thermal bridges or similar transport losses arise.

The present invention is therefore based on the object of designing a device and a method of the type mentioned at the outset and to further develop that an economical and effective production of gas can be realized.

According to the invention, the above object is achieved with regard to a device for generating gas with the features of patent claim 1. According to this, a device for generating gas is characterized in that heating pipes in the area of the fluidized bed extend at least partially through the fluidized bed.

In the manner according to the invention, it was first recognized that the use of individual heating tubes enables heat transfer even with small heating surfaces of simple geometry. In this respect, complex manufacturing is avoided.

In addition, it has been recognized that the use of heating tubes enables a wide variety of media to be passed through the heating tubes, the media being able to heat the heating tubes. All fluid media are conceivable, so that a particularly effective heat transfer is made possible by choosing an appropriate flow rate of the media. The use of heating pipes allows a high throughput of fluid, hot media, so that cooling of the heating pipes can be prevented very easily. As a result, effective heat transfer to the material to be gasified is possible.

Finally, it has been recognized that heating tubes can be positioned in a fluidized bed reactor without any problems, since, owing to their aerodynamically favorable geometry, they hardly disturb the fluidized bed. It has also been ingeniously recognized that the use of heating tubes realizes a particularly high availability of the reactor, since each heating tube can be replaced and repaired individually without switching off the reactor.

Accordingly, a device for generating gas is specified in which an economical and effective generation of gas is realized.

The heating tubes could extend through the entire fluidized bed. With this configuration, an optimized heat transfer is also possible in the center of the reactor or the fluidized bed, since the heating tubes are, for example extend from one reactor wall to the opposite. A cylindrical configuration of the reactor or a configuration as a sphere is of course also possible.

The heating pipes could be oriented horizontally. This ensures that heat radiation can be emitted vertically upwards over a maximum area and thus a particularly effective heat transfer from the heating pipes to the material is possible.

The heating pipes could be oriented vertically. This embodiment realizes a low flow resistance, since flows running from bottom to top can form streamlines along the heating pipes.

The heating pipes could be oriented parallel to one another. In this way, for example in the case of vertical arrangement of the heating tubes, it is possible to stabilize the flow in the fluidized bed, since the tubes serve as a guide for the streamlines.

The heating tubes could form one or more different angles with the horizontal. Depending on the choice of the angle, the effective heat radiation surface of the heating pipes acting vertically upwards can be set, so that areas of different heat radiation can be defined in the reactor. Against the background of this effect, the heating pipes could also enclose one or more different angles with one another.

The heating tubes could form the sides of a triangle or rectangle. This ensures that the material can flow through the surfaces spanned by the triangles or quadrilaterals. Here, the material can reach high speeds and is only disturbed by the pipes in its movement.

The heating pipes could be arranged in a star shape. The tubes could converge in the middle of the star in a beam and touch or define a round or other shaped opening with their ends. If an opening is formed, a focusing effect on the flow of the fluidized bed can occur can be achieved, which causes a particularly suitable speed profile with regard to the gasification reaction. Material can pass through the opening at high speed and collide with other hot material particles. As a result, special effects can be achieved in certain reactions at phase interfaces, which can bring about an increase in sales.

The heating tubes could be arranged in mutually parallel or inclined planes. This configuration results in an even temperature distribution in the reactor. In addition, the material to be gasified can collide several times in succession with the hot surfaces of the heating pipes and be stimulated to react. Of course, it is also conceivable that the surfaces of heating tubes which only partially protrude into the fluidized bed and do not extend from the reactor wall to the reactor wall overlap those of other heating tubes.

The heating pipes could be heated by a flame burning in the heating pipe to radiate heat. This specific configuration enables a uniform temperature profile along a heating tube, since the flame can burn in an elongated form along the heating tube. In this respect, there is no temperature gradient along the heating pipe. A flame burning in the heating pipe can heat the heating pipe to such an extent that the radiant heat from the heating pipe enables effective heat transfer to the material to be gasified. Depending on the temperature of the flame, the wavelength of the thermal radiation can be influenced. It is also advantageous that free convection can occur in the fluidized bed due to density differences within the fluidized bed. For example, it is conceivable that the density of the fluidized bed in the immediate vicinity of a heating pipe is significantly lower than at some distance. The heat transfer coefficient could be significantly influenced by the resulting convection, which can ultimately have a positive effect on the effectiveness of the entire process.

The heating pipes could be heated by burning gas. The use of gas advantageously makes it possible that even process gas generated in the gasification process can be circulated and used for heating material to be gasified. A modification of the flame could be created by adding air to the heating tubes. The addition of air could change the gas concentration and thus the temperature of the flame, so that the radiation characteristics of the heat radiation can be influenced. It is also conceivable that the air is supplied at a certain flow rate, so that the shape of the flame within the heating tube is modeled by the air flow. The shape of the flame has a significant influence on the heat transfer from the flame to the heating tube material.

Gases could be conducted in countercurrent in the heating pipes. This measure has the advantage that the temperatures of different gases can be used to heat or cool the heating pipes. For example, it is conceivable that hot gases flow along one side of the heating tube and cool gases along another. A spiral guide around the axis of the heating tube is also conceivable, which enables a particularly uniform temperature distribution in the entire heating tube.

Burnt gas, especially flue gas, could be drawn out of the heating pipes in countercurrent to fresh gas to be burned. This measure effectively uses the temperature of the hot flue gas burned to heat the heating pipe and freshly supplied gas. In addition, a rapid supply of fuel to the flame is possible.

The temperature distribution in the fluidized bed and its fluidization could be adjusted by arranging the heating pipes in the reactor. It is conceivable that the heating tubes are arranged in any orientation within the reactor. For example, it is conceivable that the heating pipes define different levels in the fluidized bed. Triangular or rectangular fields or frames that are delimited by the heating pipes are also conceivable in any orientation. A suitable geometric arrangement of the heating pipes can prevent temperature gradients or unfavorable flows from forming inside the reactor. In this respect, an even temperature distribution and suitable swirling is always guaranteed. The fluidized bed could be generated or fluidized by supplying water vapor. The use of water vapor in allothermal gasification processes enables the gas produced to be nitrogen-free and low in tar. In addition, it has a low dust load. The water vapor could be generated by waste heat from the process, the water vapor having a temperature between 650 ° C and 670 ° C degrees Celsius. This ensures an economic process while reducing the supply of external energy.

The water vapor could be introduced into the reactor from below. This embodiment of the method effectively uses the effort of the water vapor to escape upwards, so that a fluidized bed is generated in a particularly favorable manner in terms of flow and energy.

The steam could be blown into the reactor through steam nozzles. The provision of steam nozzles allows the fluidized bed to be modified so that the water vapor can be blown into the fluidized bed at different speeds. In this respect, various characteristic forms of the flow characteristics of the fluidized bed are conceivable, which can be adjusted depending on the application and reactivity of the material to be gasified.

The fluidized bed could be generated by injecting water vapor with the addition of the material to be gasified into the fluidized bed. This measure ensures that the material to be gasified is swirled immediately and is therefore subjected to heat exchange particularly quickly. This ensures that the desired reactions are particularly homogeneous and rapid.

In the reactor space above the fluidized bed, the so-called "freeboard", a heating tube for radiating heat could be introduced. This could be a heating tube with a jacket, whereby the heating tube is protected in a particularly advantageous manner Heat distribution between the fluidized bed and the rest of the reactor space, so that no undesirable temperature gradient can form in the entire reactor space are generated, which make it possible to impart very special flow properties to the fluidized bed.

The heat distribution could be adjusted both in the fluidized bed and in the rest of the reactor space through the heating tube. It is conceivable that there is a feedback between the individual heating pipes, which regulates the temperatures of the individual heating pipes according to a predetermined algorithm. It is advantageous here that overheating of the fluidized bed or similar undesirable effects can be regulated and controlled by an inherently dynamic process. In addition, suitable temperatures can be used to avoid or selectively limit undesirable post-reactions both in the fluidized bed and in the fluidized bed-free reactor space.

Defined solid particles could be introduced into the reactor space above the fluidized bed. Fine ash and coke particles in particular have a high surface area due to their very fine grain size and can therefore absorb heat radiation very well. The defined entry of solid particles in the expansion space allows very special reactions that can take place independently or overlaid to reactions in the fluidized bed.

The solid particles could be exposed to a higher temperature than that of the fluidized bed. This measure enables selective reactions which are not possible in the fluidized bed due to the lower temperature. Particularly reactive gas components can advantageously be treated and possibly selectively subjected to a rapid aftertreatment.

Furthermore, the above object is achieved with regard to a method for producing gas with the features of patent claim 22. According to this, a method for producing gas of the type mentioned at the outset is characterized in that heating tubes which extend at least partially through the fluidized bed are used in the region of the fluidized bed.

In order to avoid repetitions, with regard to advantageous embodiments of the method, reference is made to the explanations regarding the device. There are now various possibilities for advantageously designing and developing the teaching of the present invention. For this purpose, reference is made to the subordinate claims, on the one hand, and to the following explanation of two preferred exemplary embodiments of the device according to the invention and of the method according to the invention, using the drawing. In connection with the explanation of the preferred exemplary embodiments with reference to the drawing, generally preferred refinements and developments of the teaching are also explained. Show in the drawing

Fig. 1 is a sectional view of the reactor of the device, in which a

Fluidized bed is generated, and

Fig. 2 is a schematic diagram of the inventive method for

Purification of gas using a special embodiment of the device.

1 shows a sectional view of the reactor 1 of the device, in which a fluidized bed 2 is generated. The fluidized bed 2 is heated by individual heating tubes 3 which extend through the fluidized bed 2. The heating tubes 3 are arranged one above the other, horizontally and parallel to one another in the fluidized bed 2 and extend through the entire fluidized bed 2.

The heating tubes 3 are heated by a flame burning in the heating tube 3 to radiate heat. Gas 4 is introduced into the heating pipes 3 and is burned by a flame. Air 5 is also supplied to the heating pipes. Flue gas 6 is led out of the heating pipes 3 in countercurrent to fresh gas 4.

The fluidized bed 2 is fluidized by supplying water vapor 7. The steam 7 is introduced into the reactor 1 from below. The steam 7 is blown into the reactor 1 through steam nozzles 8.

The material 9 to be gasified is added to the fluidized bed 2 while injecting water vapor 7. The material 9 is gasified in the reactor 1 allothermally Gas 10 is generated. The generated gas 10 leaves the reactor 1 at its upper end via an outlet and can be treated further.

2 shows an embodiment of the device in which a heating tube 11 is arranged in the reactor space above the fluidized bed 2. The heat distribution both in the fluidized bed 2 and in the rest of the reactor space is adjusted by the heating tube 11. Undesired post-reactions are avoided by choosing suitable temperatures. Solids that are deposited on the bottom of the fluidized bed can optionally be removed by clocked slides.

Defined solid particles, in particular ash or coke, are introduced into the reactor space above the fluidized bed 2. Due to their large surface area, the solid particles absorb heat radiation, the solid particles taking on a higher temperature than the fluidized bed temperature. This increases the conversion of carbon, which leads to an increase in the efficiency of gasification.

Finally, it should be emphasized that the exemplary embodiments described above discuss the claimed teaching, but do not restrict it to the exemplary embodiments.

Claims

claims

1. Device for generating gas (10), in particular hydrogen-rich synthesis gas from biogenic or other carbon-containing material (9), the material (9) being gasified allothermally in a reactor (1) to produce a fluidized bed (2) and the fluidized bed ( 2) is heated, characterized in that in the area of the fluidized bed (2) heating tubes (3) at least partially extend through the fluidized bed (2).

2. Device according to claim 1, characterized in that the heating tubes (3) extend through the entire fluidized bed.

3. Device according to claim 1 or 2, characterized in that the heating tubes (3) are oriented horizontally.

4. Device according to one of claims 1 to 3, characterized in that the heating tubes (3) are oriented vertically.

5. Device according to one of claims 1 to 4, characterized in that the heating tubes (3) are oriented parallel to each other.

6. The device according to claim 1 or 2, characterized in that the heating tubes (3) include one or more different angles with the horizontal and / or with each other.

7. Device according to one of claims 1 to 6, characterized in that the heating tubes (3) form the sides of a triangle or rectangle.

8. Device according to one of claims 1 to 6, characterized in that the heating tubes (3) are arranged in a star shape.

9. Device according to one of claims 1 to 8, characterized in that the heating tubes (3) are arranged in mutually parallel or inclined planes.

10. Device according to one of claims 1 to 9, characterized in that the heating tubes (3) can be heated by a flame burning in the heating tube (3) to radiate heat.

11. The device according to claim 10, characterized in that the heating tubes (3) can be heated by burning gas (4).

12. The device according to claim 10 or 11, characterized in that the heating tubes (3) air (5) can be fed.

13. Device according to one of claims 10 to 12, characterized in that gases can be conducted in countercurrent in the heating tubes (3).

14. The apparatus according to claim 13, characterized in that burned gas (6), in particular flue gas, can be led out of the heating pipes (3) in countercurrent to fresh gas to be burned.

15. The device according to one of claims 1 to 14, characterized in that the temperature distribution in the fluidized bed (2) by the arrangement of the heating tubes (3) in the reactor (1) is adjustable.

16. Device according to one of claims 1 to 15, characterized in that the fluidized bed (2) can be generated or fluidized by supplying water vapor (7).

17. The apparatus according to claim 16, characterized in that the water vapor (7) can be introduced into the reactor (1) from below.

18. The apparatus according to claim 16 or 17, characterized in that the water vapor (7) through steam nozzles (8) in the reactor (1) can be blown.

19. Device according to one of claims 16 to 18, characterized in that the fluidized bed (2) can be produced by injecting water vapor (7) with the addition of the material to be gasified (9) into the fluidized bed.

20. Device according to one of claims 1 to 19, characterized in that a heating tube (11) is arranged in the reactor space above the fluidized bed (2).

21. The apparatus according to claim 20, characterized in that the heat distribution in the fluidized bed (2) and in the rest of the reactor space is adjustable by the heating tube (11).

22. A method for generating gas (10), in particular hydrogen-rich synthesis gas from biogenic or other carbon-containing material (9), in particular using a device according to one of claims 1 to 21, wherein the material (9) in a reactor (1 ) gasified allothermally to produce a fluidized bed (2) and the fluidized bed (2) is heated, characterized in that heating tubes (3) extending at least partially through the fluidized bed (2) are used in the area of the fluidized bed (2).

23. The method according to claim 22, characterized in that the heating tubes (3) are heated by a flame burning in the heating tube (3) to radiate heat.

24. The method according to claim 22 or 23, characterized in that the heating tubes (3) are heated by burning gas (4).

25. The method according to any one of claims 22 to 24, characterized in that the heating pipes (3) air (5) is supplied.

26. The method according to any one of claims 22 to 25, characterized in that gases are conducted in countercurrent in the heating tubes (3).

27. The method according to claim 26, characterized in that burnt gas (6), in particular flue gas, is led out of the heating pipes (3) in countercurrent to fresh gas to be burned.

28. The method according to any one of claims 22 to 27, characterized in that the temperature distribution in the fluidized bed (2) is adjusted by the arrangement of the heating tubes (3) in the reactor (1).

29. The method according to any one of claims 22 to 28, characterized in that the fluidized bed (2) is generated or fluidized by supplying water vapor (7).

30. The method according to claim 29, characterized in that the water vapor (7) is introduced into the reactor (1) from below.

31. The method according to claim 29 or 30, characterized in that the water vapor (7) is blown through steam nozzles (8) into the reactor (1).

32. The method according to any one of claims 29 to 31, characterized in that the fluidized bed (2) is generated by injecting water vapor (7) with the addition of the material to be gasified (9) into the fluidized bed.

33. The method according to any one of claims 22 to 32, characterized in that a heating tube (11) is used in the reactor space above the fluidized bed (2).

34. The method according to claim 33, characterized in that the heat distribution in the fluidized bed (2) and in the rest of the reactor space is adjusted by the heating tube (11).

35. The method according to any one of claims 22 to 34, characterized in that defined solid particles are introduced into the reactor space above the fluidized bed (2).

36. The method according to claim 35, characterized in that the solid particles are subjected to a higher temperature than the fluidized bed temperature.