DD155174A1 - METHOD FOR OPERATING A HORIZONTAL REACTOR FOR GASOLATING CARBONATIVE MATERIAL - Google Patents

Abstract

A method of operating a fluidized bed reactor for gasifying carbonaceous material using gasification means having exothermic and endothermic reactions with a post reaction space above the fluidized bed which is pervaded by the gaseous mixture and carbonaceous particulates leaving the fluidized bed, with gasification agents being introduced into the fluidized bed over at least three blowing zones arranged along the reactor longitudinal axis are blown into the after-reaction chamber, should be carried out so that as high as possible a constant temperature along the reactor axis is maintained above the fluidized bed in the post-reaction space. This is achieved by appropriately metering the addition of the gasification agent along the reactor axis. In this way, as far as possible a conversion of the carbonaceous particles with the formation of usable gases should be achieved with the lowest possible cost of gasification agents as possible with the most advantageous composition.

Description

-4- 22

A method of operating a fluidized bed reactor for gasifying carbonaceous material

Application of the invention:

The invention relates to a method for operating a fluidized bed reactor for gasifying carbonaceous material using exothermic reactions and ¹ endothermic reactions causing gasification with a above the fluidized bed post-reaction chamber, which is flowed through by the emerging from the fluidized bed gas mixture and carbonaceous solid particles, wherein gasification agent in the fluidized bed and introduced into the post-reaction chamber via at least three Einblasebereich arranged along the reactor longitudinal axis.

For example, air, oxygen and hydrogen are used as exothermic gasification agents and water vapor and CO ₂ as endothermic gasification agents in question.

Characteristics of known technical solutions: In the gasification of carbonaceous material, e.g. Charcoal, it is known, is introduced into a fluidized bed reactor having a lower fluidized bed containing the carbonaceous particulate matter and an overreaction space thereover entrained with entrained carbonaceous particulate matter. Oxygen and water vapor, blowing in, wherein the injected into the lower region of the reactor gasification simultaneously cause the fluidization of the fluidized bed. Furthermore, it is known above the above

- 2 - 2 2 5 8 4

ren limit the fluidized bed to supply additional gasification agent. This is intended to ensure that the solids discharged upwards from the fluidized bed are gasified as completely as possible on the way through the post-reaction space. It is also known to influence the temperature distribution along the reactor axis by the addition of gasification agents in a plurality of regions spaced apart from one another along the reactor axis in the middle and / or upper region of the post-reaction space. The temperature drops from a maximum just above the upper boundary of the fluidized bed more or less continuously to a much lower temperature in the upper region of the reaction chamber.

It is necessary to stay below the melting point of the ashes of the carbonaceous material with the maximum temperature, since in the other case caking occurs in the reactor and / or in the lines in which the product gas is passed to downstream devices after leaving the reactor.

The temperature profile, ie the temperature profile along the longitudinal axis in the post-reaction chamber, is of great importance for the operation of the reactor and also for the quality of the gas produced therein. The course of the temperature is furthermore important for the greatest possible conversion of the carbonaceous material introduced into the reactor. Thus, a high temperature in the presence of carbonaceous material promotes CO and H ~ yield. Too high a temperature, however, can lead to the aforementioned caking and formation of agglomerates in melting ash, which affect the operation of the reactor or even lead to business interruptions. Although a too low temperature avoids difficulties by melting the ash, but on the other hand leads to a higher CO ₀ - and H ^ C ^ share in the

- 3 - 2 2 5 8 A 1

Product gas. In addition, the reaction of solid carbon with £ 0 ^ and H finds particularly favorable conditions.

carbon with £ 0 ₂ and HO to CO and H ₂ no

Object of the invention:

The invention is inter alia based on the object of modifying the method of the type described in the introduction in such a way that, with regard to the limits set by the ash melting point, as complete a conversion as possible of the carbonaceous material located in the post-reaction space is effected. The introduced into the reactor gasification agents should be used selectively, so that with the least possible cost of gasification a maximum effect in the sense of extensive gasification of the solid carbon particles to form usable gases can be achieved.

DISCLOSURE OF THE NATURE OF THE INVENTION To solve this problem, the invention proposes that the gasification agents be introduced into the postreaction space distributed along the longitudinal axis of the reactor in such a way that a temperature level as constant as possible along the reactor axis is maintained above the fluidized bed.

Of course, it is not possible to adhere to an absolutely constant over the elevation of Nachreaktionsraumes temperature, as practically in every plane in which gasification agent is injected, due to the then predominantly exothermic reactions, a small temperature peak is formed and then in the flow direction, ie. upward, the temperature decreases due to the then predominantly endothermic reactions. However, the number of "areas or planes in which exothermic gasification agent blows into the post-reaction space should be so large that the previous temperature drop is not very pronounced

- 4 - 22584 1

approximately Sägeza.hnartiger course of the temperature profile, with the number of Einblasebereiche or levels decreases the deviation of the upper values and the lower values of the predetermined high temperature.

It is also possible to carry out the process according to the invention in such a way that the gasification agents are introduced into the postreaction space distributed along the longitudinal axis of the reactor so that at least two clear sections of the postreaction space extending over at least two injection regions are present above the fluidized bed, in which temperature levels which are as constant as possible be maintained different heights along the reactor axis. For the second section, it is also true that the temperature is as constant as possible in the above-described sense, whereby it is optimally adjusted in adaptation to the carbon present or to be converted in each case in this area.

It is known to cool product gas immediately before leaving the fluidized bed reactor by blowing in water or steam. This quenching, as well as the lowering of the temperature in the upper portion of the post-reaction chamber - are used especially when the high temperature maintained in the post-reaction chamber is so close to the ash melting point that for the sake of reliable prevention of caking in the downstream of the reactor lines a reduction of Temperature of the product gas before leaving the Nachreaktionsraumes is appropriate. When quenching is used, the section (s) of consistently high temperature would thus extend between the fluidized bed and the quench zone. In the other case, ie without quenching, the highest possible constant high temperature in the post-reaction chamber or in the upper portion of the same would extend to just above the range in which the last supply of gasification

- 5 - 2258-4 1

It is possible to carry out the reaction of the carbonaceous solid particles located in the post-reaction space in such a way that the reaction is as constant as possible over the longitudinal extent of the post-reaction space. The supply of gasification agent in the post-reaction space over its height will also be as constant as possible.

However, there is also the possibility that the sum of the respectively added in Nachverktionsraum gasification decreases from bottom to top. An advantage of this procedure may be, for example, that the product gas leaving the reactor contains only a small amount of unused steam.

Both of the abovementioned possibilities of metering the gasification agents are based on the consideration that it is not only necessary to supply so much gasification agent at one or optionally also at two points that it suffices for the conversion of the carbon present in the post-reaction space. that known mode of operation, in which only a relatively large amount of gasification agent is added only once, namely just above the fluidized bed, in order to achieve the greatest possible conversion of the carbon-containing solid particles discharged from the fluidized bed, the conditions in the area above By the process control according to the invention a conversion over the longitudinal extension of the post-reaction space is achieved in the entire post-reaction space, which leads to clear operating conditions, so that from v Ornherein it is easier to control the desired operating characteristics, such as the Ternperaturprof i.l and. Dependent on the addition of gasification agents in an optimal manner. In particular, can be in this way despite a high average temperature

225841

- ο -

Avoid overheating, which can lead to caking and thus to malfunction. The supply of the gasification agent can be carried out in the usual manner. The distances between the individual injection areas or levels can be constant. However, it is also possible to inject the gasification agent in from bottom to top becoming larger intervals in the post-reaction space, which then in order to achieve a bottom-up decreasing Vergasungsmittelmenge possible, although not necessary to keep the injected Vergasungsmittelmenge per area constant.

It is possible to operate the gasification process in the fluidized bed in such a way that the gas and solid mixture emerging from the fluidized bed at the top essentially has the temperature which is to be maintained in the after-reaction space or in the lower portion thereof. However, it may also be expedient to carry out the gasification in the fluidized bed in such a way that the gas and solid mixture leaving it has a lower temperature than the temperature to be maintained in the after-reaction chamber or in the lower portion thereof. In this case, a corresponding increase in the addition of exothermic gasification agent close to the fluidized bed initially causes a temperature increase to be maintained in the post-reaction space temperature level. It is also possible, of course, to increase the temperature of the gas and solid mixture emerging from the fluidized bed to the desired temperature level in stages in the after-reaction chamber so that the temperature level to be maintained in the remaining portion of the post-reaction space is not reached until after a further blowing zone located above the fluidized bed is reached.

The addition of the gasification agent in the individual Einblasebereichen can be controlled depending on the temperature detected there each. It is also possible,

22 584

controlling the addition of the gasification agents as a function of other parameters, for example the carbon content of the solid particles of the gas-solid mixture flowing through the post-reaction space. In addition, there is the known possibility, by the addition of CaO and / or MgO or compounds which release CaO and / or MgO, to effect an elevation of the ash melting point.

EXAMPLES

In the drawing, some embodiments of the invention are shown. Show it:

Fig. 1 in the diagram a longitudinal section through a

Fluidized bed reactor with temperature profile shown alongside along the longitudinal axis of the reactor,

Fig. 2 is a representation corresponding to FIG. 1

another embodiment,

Fig. 3 is a representation corresponding to FIG. 1

a third embodiment.

In the lower .Bereich of a fluidized bed reactor 10 to be gassed fuel and possibly additives, for example, serve to increase the ash melting point, by a indicated at 12 feeder, which may be formed as a screw or otherwise suitably; brought in. Under the influence of gasification agents, which are blown near the lower end at 14 in the fluidized bed reactor, a fluidized bed 15, whose upper and lower boundary 16 and 17 are designated builds. Below the lower boundary 17 there is a layer 18, the at least predominantly ash-containing parts of which are discharged through an opening 19 located at the lower end of the reactor 10.

The gasification agents which cause the turbulence of the bed 15 can normally be oxygen-containing gasifying agents which cause an exothermic reaction,

- 8 - 2 2 5 8 A 1

and act to steam and / or CO, so to effect an endothermic conversion gasifying agent. The gases can be injected through nozzles, several of which are arranged distributed over the circumference of the reactor, wherein it is possible, endothermic reactions causing gasification and exothermic gasification agent causing effect also in two separate, z. B. superposed areas or levels.

It is unavoidable that at least part of the finer solid particles from the fluidized bed 15 is entrained in the above-mentioned after-reaction chamber 20 by the upwardly flowing gas mixture. The latter is once the gaseous reaction products from the fluidized bed and on the other to residues of unreacted gasification agents, in particular steam. The solid particles still contain carbon which is to be converted within the post-reaction space. The necessary heat is supplied by burning a portion of the combustible gases contained in the gas mixture, essentially CO and H ₂ / and a portion of the carbonaceous solid. The required means, z. As oxygen, is injected through lines and nozzles, which are distributed along the longitudinal axis of the reactor above the fluidized bed 15 into the post-reaction chamber 20 and 21, 23, 25 and 27 are designated. Again, it is true that in each case a plurality of lines or nozzles distributed over the circumference of the Nachreaktionsraumes can lead into these. Furthermore, through the nozzles. 21, .23, 25 and 27 injected gasification agent into the post-reaction chamber 20. It is possible, on the one hand, to blow exothermically reacting gases on the one hand and endothermically reacting gases, on the other hand, in a mixture or else by means of separate feed systems and nozzles. In the temperature profile shown in FIG. 1 next to the reactor 10, the levels in which gasification agents are introduced into the post-reaction space 20,

- ⁹ - 2 2 5 8 4 1

indicated by dashed lines, which end at the individual Einblasebenen corresponding lines or nozzles associated arrows.

In the fluidized bed 15, due to the exothermic conversion of the coal with the gasification agent fed at 14, a relatively high and uniform temperature builds up, which should amount to approximately 1050 ° C. in the exemplary embodiment shown in FIG. So it is z. B. in a less dense fluidized bed readily possible to maintain a maximum temperature, which is close to the given by the melting point melting point temperature. The first supply of gasification agent into the post-reaction chamber 20 takes place via the supply lines 21, which is located at a relatively short distance above the upper boundary 16 of the fluidized bed 15. When operating a reactor with higher gas velocities in the fluidized bed, a larger proportion of fine grain is entrained in the post-reaction space. This may thus be that the boundary between the fluidized bed, on the one hand, and the solid particles distributed in the post-reaction chamber, on the other hand, is not very sharp, the difference in the number of solid particles per unit volume between the fluidized bed on the one hand and the post-reaction chamber, on the other hand, is thus relatively low. Part of the fluidized bed leaving combustible gases, especially E ₀ and CO, and the solid particles are z. B. oxygen of the supplied via the leads 21 Vergasungsmittelgemisches burned. This results in a corresponding, depending on the amount of oxygen and thus the amount of the burned gases and the carbonaceous solid particles temperature increase up to the upper temperature of about 1100 ° C, which is reached in the apex region of the peak 30 just above the Einblaseebene 21a. This additional supply of heat favors the conversion of the carbon of the particles located in the post-reaction space with the likewise supplied via supply line 21 -zB-

- IQ -

22584 1

and steam to form CO and H ~. This gasification reaction consumes heat, so that in the course of the upward movement of the gas mixture, this again experiences a reduction in its temperature. It is then, as soon as the temperature reduction has exceeded a certain level - in the embodiment shown in Fig. 1 of the drawing upon reaching a temperature of about 1050 ° C - through the supply lines 23, 25, 27 again exothermic and endothermic reacting Vergasungsmittel'in blown the post-reaction chamber 20 in the Einblaseebenen 23a, 25a, 27a, wherein each of the described reaction sequence occurs.

Shortly before the outlet opening 28 of the reactor via quenching means 40 in the plane 40a quenching agent is added to the post-reaction chamber, which reduces the temperature of the gas by about 80 to 100 ° C, to ensure in this way that the gas leaving the reactor mixture no solid particles whose ash is softened and could cause clogging in downstream lines.

Due to the carbon conversion, the amount of solid carbon in the post-reaction chamber 20 decreases from bottom to top, so that consequently from bottom to top, less gasification agent is needed for the reaction. This is taken into account in the embodiment according to FIG. Γ that the distances between the Einblaseebenen 21 a, 23 a, 25 a and 27 a increase from bottom to top.

In the embodiment according to FIG. 2, the temperature within the fluidized bed 115 is substantially lower than in that according to FIG. 1. It is between approximately 700 and 800 ° C. Thus, the addition of exothermically reacting gasification agent is immediately above the upper boundary 16 of the fluidized bed 115 in the Einblaseebene 121 a dimensioned so that the flowing out of the fluidized bed gas and solid

2 2 5 8

a significant increase in temperature of the top temperature of the peak 130 reaching to the peak 136 reaching lower portion consistently high temperature of about 1100 ° C undergoes. The subsequent operation corresponds to the Einblaseebene 127 a, d. H. however, the supply lines 121, 123, 125, 127 on the one hand and the supply lines 142, 144 on the other hand and consequently also the associated injection regions or planes 121a, 123a, 125a, 127a , On the one hand, and the Einblasebegee or levels 142a, 144a on the other hand are arranged at substantially constant vertical distances from each other. That is, the decrease in the addition of the gasifying agents from the bottom to the top is effected by a corresponding reduction in the amount per one bubble level.

In contrast to the exemplary embodiment according to FIG. 1, there are six instead of four supply lines and injection regions, wherein after the peak 136 associated with the injection region 127a, the average temperature, which until then is 1075 ° C., is lowered by 40 ° C., so that at an amplitude of 50 ° between the upper and lower values, the temperatures in the following, in the flow direction 148 on the peak 136 following range between 1010 and 1060 ° C vary. This means that in this section the constantly high temperature level is slightly reduced compared to the lower section, in order to adapt to the solid carbon still present in the after-reaction space in this area. Ie. in that the optimum temperatures are set in each of these areas.

As already mentioned above, when operating a fluidized bed reactor with higher gas velocities, a larger proportion of fine grain can be entrained in the postreaction space. The amount of this entrained fine grain can be of the order of magnitude of the carbonaceous material freshly introduced into the fluidized bed reactor or

225

also be much bigger. In such an operation, in general, the excreted from the product gas fine grain, which normally still contains carbon, in addition to the freshly introduced into the reactor carbon in the fluidized bed, ie in the reactor, recycled.

In this case it is expedient to inject the exothermically reacting gasification agent in equal quantities over the injection regions arranged along the longitudinal axis of the post-reaction space. The blowing of the endothermic gasifying agent along the longitudinal axis of the post-reaction chamber depends on the desired uniform reaction at a uniform temperature profile. It is such that of the injected into the lower Einblasebereich endothermic gasification agent depending on the concentration of the carbonaceous material in the post-reaction only one or less portion is reacted, so that at the upper Einblasebereichea in Nachreaktionsraum the ratio between exothermally reacting and endothermically reacting Vergasungsmittelmengen remains constant or can increase. In this procedure, the Einblasebereiche can be arranged in the post-reaction chamber with the same distance from each other. The temperature profile resulting from this procedure gives a uniform sawtooth-shaped up and down of the temperature over the length of the post-reaction space.

The above-described procedure is possible in connection with the embodiment shown in Fig. 3 of the drawing. The temperature in the fluidized bed 215 corresponds approximately to that of the embodiment according to FIG. 1, although that according to FIG. 2 is also possible. The Einblasebereiche 221 to 227 are arranged at equal intervals. In all injection planes 221a to 227a, the exothermically reacting and the endothermically reacting gasification agents are added in constant proportions.

- 13 - 2 2 5 8 4 1

blown each other and optionally also in constant amounts. The latter would mean that equal amounts of endothermically reacting and exothermic gasification agents are injected over all injection zones from bottom to top. Shortly before the outlet opening 228, as in the exemplary embodiments according to FIGS. 1 and 2, quenching means can be supplied via a feed line 240.

Irrespective of whether the temperature of the gas and solid mixture emerging from the fluidized bed already has the temperature to be maintained in the post-reaction space or is only brought to the temperature prevailing in the post-reaction space above the fluidized bed, the reaction of the carbonaceous material in the post-reaction space applies for all embodiments Solid particles should be performed so that heat consumption and heat supply to each other such that in the individual sections a constant temperature level is maintained or - more precisely - the temperature within the post-reaction space or the sections on the or the axial extent to a mean only varies slightly on both sides, with the maximum temperature occurring possibly close to the temperature limit at which the softening of the ash particles to difficulties, d. H. could lead to caking or formation of larger agglomerates.

Of course, the temperature profile is shown idealized in all figures of the drawing. The crucial point is that the temperature fluctuations around an average temperature, which in turn can vary by a small amount, are kept as small as possible, and the amplitude does not need to be constant over the entire length of the post-reaction space. Instead, it can fluctuate within limits along the reactor axis, ie become larger or smaller.

Claims (18)

2258Λ1 Invention claim: 1. A method for operating a fluidized bed reactor for gasification of solid, carbonaceous material using exothermic and endothermic reactions causing gasification with an above the fluidized bed post-reaction / flows through the emerging from the fluidized bed gas mixture and carbonaceous solid particles _t wherein gasification in Fluidized bed are introduced into the post-reaction chamber via at least three arranged along the reactor longitudinal axis Ijjinblasebereichen, characterized in that the gasification medium distributed along the reactor longitudinal axis are introduced into the post-reaction that one or more consistent as possible, high temperature levels are maintained along the reactor axis above the fluidized bed. 2. The method according to item 1, characterized in that the highest possible constant high temperature in the after-reaction chamber or in the upper portion of the same is maintained until just above the range in which the last supply of gasification takes place before the reactor outlet. ^f ) i ^s ΓΓΠ 1 Γ, Γ; A 2 5 8 3. The method according to item 1, characterized in that the temperature level in the upper section is lower than in the lower. 4. The method according to item 1 or 2, characterized in that the sum of the respectively added in the post-reaction chamber in each section gasification agent decreases from bottom to top. 5 .. Method according to item 1 or 2, characterized in that the sum of each to be added in the post-reaction chamber in each section gasification agent from bottom to top remains constant. 6. The method 'according to item 1 or 2, characterized in that the amount of gasification agent causing exothermic reactions is kept constant in each section. 7. The method according to item 1 or 2, characterized in that the amount of gasification agent causing exothermic reactions decreases in each section from bottom to top. 8. The method according to item 4, characterized in that both the amount of gasification agent causing the exothermic reactions and the amount of the gasifying agent effecting endothermic reactions decrease in each section from bottom to top. 9. The method according to item 1, characterized in that the ratio between gasification agent causing exothermic reactions and gasification means causing endothermic reactions increases from bottom to top in each section. 10. The method according to item 1, characterized in that the ratio between gasification agent causing exothermic reactions and gasification agent causing endothermic conversions in each section is from bottom to top. ib 2 5 8 remains constant. 11. The method according to item 1, characterized in that the gasification agents are introduced into from bottom to top becoming larger intervals in the post-reaction chamber or in the sections. 12. The method according to item o, characterized in that the upwardly emerging from the fluidized bed of solid-gas mixture, a temperature which is approximately equal to the temperature which is the same in the post-reaction chamber or in the section located above the fluidized bed to comply , 13. The method according to item 1, characterized in that the solid-gas mixture exiting from the fluidized bed has a lower temperature than the temperature to be maintained in the post-reaction chamber or in the section located above the fluidized bed and by, corresponding addition of an exothermic Implementing effecting gasification close to the fluidized bed a, uf the space to be maintained in the post-reaction chamber or in the section located above the fluidized bed is brought. 14. The method according to item 1, characterized in that the. Gasification agents are introduced in at least four, spaced-apart areas in the post-reaction chamber. 15 .. Method according to item 1, characterized in that the gasification agent in. At least six distances, mutually having regions are introduced into the post-reaction chamber. , , 22584 1 16. The method according to item 1, characterized in that the addition of an exothermic reaction causing gasification agent is controlled in the individual Einblase areas depending on the temperature and / or solids content determined there. 17. The method according to item 1, characterized in that the addition of an endtherme conversion effecting gasification agent is controlled in the individual Einblasebereichen depending on the existing there carbonaceous solid. 18. The method according to item 1, characterized in that the gasification means are injected in substantially horizontal planes in the post-reaction chamber. For this ..... J .... pages drawings