DE2926034C2 - Method and apparatus for generating gas from solid fuels with a fluidized bed - Google Patents

Description

so The invention relates to a method for Generation of gas from solid fuels according to the preamble of claim 1 and in particular A device for gasifying in a cyclone which can be used in such a process deposited particles.

In the process for generating gas from solid fuels with gasification agents specified in the main patent there is a fluidized bed from which the residues are discharged below and from which the im from

solids contained in the fluidized bed rising gas separated by centrifugal force. These solids are in a separately supplied gasification agent operated, separated from the fluidized bed side reaction in one the fluidized bed and the

· >> Slag melting temperature exceeding temperature post-gasified and the resulting reaction products fed to the fluidized bed. The Solids within the generator above the

Fluidized bed separated and immediately post-gasified and all post-gasification products directly into the fluidized bed passed, with the melt in the fluidized bed - and possibly in one below Fixed bed - cooled down to solidification Such a process enables inter alia. better use of the The total carbon added to the process in the fuel reduces the load on the gas flow and allows the overall process to be carried out cheaply. i "

According to the method described in the main patent, these advantages are achieved above all in that there is a post-gasification chamber connected to the cyclone, the transition area of which at the same time forms the outlet of the cyclone. In the transition area there is an injector, via which gasifying agent, namely superheated steam and oxygen, can be supplied from the outside at a pressure which is correspondingly higher than the pressure in the generator. The solids separated in the cyclone .w are in the outlet of the cyclone by the gasifying agent jet emerging from the injector! detected and post-gasified in the post-gasification chambers in a temperature range of about 1300 ⁰ C to 1500 ⁰ C, ie above the ash melting point falls down into the fluidized bed in the form of drops. As a result of the high-temperature post-gasification in the post-gasification chamber, there are no dry ash particles that were caught by the gas flow from the fluidized bed and would have to be separated again in the cyclone. There is also the advantage that the heat jet from the post-gasification chamber additionally heats the fluidized bed.

From "Freiberger Forschungshefte", A 69 (1957), pp. 20/21, a melting chamber is known in which from flue dusts separated and collected by means of a cyclone in a winkler generator Addition of steam above the ash melting temperature outside the generator burned and the hot Combustion gases are fed back to the generator. - The DE-OS 10 23 844 describes a corresponding procedure with disconnected from the generator Ί5 The flue dust combustion zone, which, however, works below the ash melting temperature and the combustion products under a fixed bed of coke in the generator. The DE-OS 26 40 180 finally describes a generator with successive fixed bed, fluidized bed and dust gasification zones. wherein the dust gasification zone is arranged within the generator.

The object of the invention is to improve and design the method according to the main patent still writer. This is particularly true with regard to the gasification processes involved in the cyclone Particles. Furthermore, the invention aims to provide an advantageous device for generating gas gasification of particles deposited in a cyclone, made from solid fuels, and in the individual are inexpensive. With all of that Related other problems with which the invention is concerned emerge from US Pat respective explanation of the solution shown.

The invention envisages that those in the cyclone deposited particles are accumulated and removed from this accumulation by means of a gaseous conveying medium in the area for the gasification of the particles with the generation of an at least partially rotary movement or circulation movement in this area are transported .and that oxygen spatially is introduced into the gasification area separately from the pumped medium. This makes a particularly inexpensive one The sequence of reactions taking place in the gasification area of the particles is achieved by the rotation or Circulation movement, the paths of the particles within the gasification area are lengthened, so that a particularly intensive mixing with reactants occurs

For this purpose, the conveying medium with the particles it has picked up is advantageous essentially introduced secantially into the gasification area. The oxygen supply can in particular take place centrally.

All gaseous substances suitable or required for the gasification process can be used as the conveying medium; B. CO ₃ , steam or fuel gas with any composition. It is particularly advantageous to take a recirculation amount from the product gas generated, expediently after a gas purification, and to use this gas as a conveying medium, if necessary after appropriate compression Carbon monoxide. This then also applies to the recirculation gas used. The use of a recirculation gps has the advantage that it is to be regarded as non-reactive (quasi-inert) with respect to the atmosphere of the cyclone and the process. There is no reaction when it flows into these spaces because it has almost the same analysis. A recirculation gas used as a conveying medium for the particles separated in the cyclone can advantageously be admixed with water vapor and / or carbon dioxide.

The conveying medium loaded with the absorbed solid particles from the cyclone, in particular recirculation gas, reaches the separate gasification area, where the oxygen is injected, which reacts spontaneously exothermically with part of the gas, so that so much heat is released that in a temperature of 1600 ° C to 1800 ⁰ C can set this gasification range. This temperature can be regulated very precisely via the supplied amount of oxygen and / or via the supply of certain amounts of inert gas or water vapor in the delivery medium or in addition to this.

The amount of oxygen introduced into the gasification area is, in one convenient embodiment of the process is set substoichiometric (A <1) -'c compared to the amount of gas offered. It is then guaranteed that a complete conversion of the oxygen always occurs and the theoretical combustion temperature of partial combustion with an oversupply of gas, especially gasification agent, is cooled down.

As a result of the high temperature in the area of the combustion and gasification processes explained the ash components are brought into the liquid phase state. By injecting the The conveying medium loaded with the particles, in particular the recirculation gas, into the gasification area the already liquefied slag droplets are set in a rotating motion and through Centrifugal forces to the wall of the gasification chamber

carried.

The invention also provides, by means of a completely or at least almost completely of gasification agent, in particular water vapor, existing conveying medium consisting as far as possible of carbon Bringing particles into the gasification area and burning or gasifying them there. This is whole very cheap. According to the invention, oxygen can then also be in a stoichiometric or greater amount Amount to be introduced.

An advantageous device with a cyclone and a gasification chamber assigned to it for the gasification of particles separated in the cyclone is characterized according to the invention in that the gasification chamber has at least one inlet for oxygen and at least one inlet separate from it for a conveyance loaded with the particles separated in the cyclone? nr>? di " ^r ·.!, where the inlet has at least one connection for the conveying medium, at least one inlet for the separated particles opening into the path of the conveying medium and a nozzle-like outlet directed essentially secantially into the gasification chamber.

The outlet of the cyclone is advantageously designed so that the separated particles settle in it and 2; then via the shortest possible connection, preferably directly, into the inlet of one or more Introductions arrive. If the particles have to be conveyed into a chamber in which the pressure in the is substantially higher by the pressure loss of the cyclone than in the outlet of the latter, the conveyor system must for the particles to be able to increase this pressure difference overcome and at the same time generate the kinetic energy for the transport of the particles. Suitable for this Entries can be designed in various ways, for example as an injector. With a cheap Training, the introduction is designed in the manner of a Venturi nozzle. Experiences a gas flow as a conveying medium in the narrowest point of such a nozzle so far a static pressure drop that the particles due to their -to Gravity fall into the conveying gas flow and are transported by this into the gasification chamber.

The device can be used with the cyclone within a gas generation and a fluidized bed containing generator vessel be arranged. But it is also possible to put the cyclone above or on to be arranged elsewhere outside of the generator vessel, but then at least the lower The end of the gasification chamber is located within the generator vessel or opens into the same, such that the resulting reaction products can enter the fluidized bed from the gasification chamber.

Further details, features and advantages of the invention emerge from the following explanation, from the drawing and from the claims. It shows

F i g. 1 largely shows a generator in vertical longitudinal section with the device according to the invention schematic,

Fig.2 which is at the lower end of a cyclone adjoining part of the device, partly in section,

3 shows a section along the line M-IH in FIG and

4 shows a detail from FIG. 2 in a larger scale Scale.

The generator according to FIG. 1 has a generator vessel G which surrounds the entire reaction space.

which contains a fluidized bed gasification zone and a fixed bed gasification zone F underneath. This means that a fixed bed generator and a fluidized bed generator W are provided in connection with one another in one and the same generator vessel C.

The fixed-bed gasification zone F for gasifying the fuel in a stationary or quasi-stationary shift has the shape of a shaft and is equipped with a rotating grate 4 of a known type. With the number 5 are in the Rotary grate opening feed lines for gasifying agents (e.g. air or oxygen and / or water vapor, depending on according to the process to be carried out or the desired gas). To discharge the Gasification residues from the fixed-bed gasification zone F is used by a lock 6 of a known type.

In the fluidized bed gasification zone W which adjoins the fixed bed gasification zone F Inlets 10 are provided for the fuel. The fuel entry devices each have a drivable screw conveyor II, which the fuel from a supply via a lock 13 is supplied of a known type. Instead of a screw conveyor, another device can also be used be provided for introducing the fuel. z. B. a slide, a vibratory conveyor or the like.

Below the fuel inlets 10 are a plurality of feed lines 14 for gasifying agents (for example air, oxygen, water vapor), each of which is arranged in a ring-shaped manner distributed over the circumference. Their inlets opening into Zone W are at different heights, as can be seen from the drawing. This part of the vessel G , which includes the fluidized bed gasification zone VV, has an inner cross section which widens towards the top, in particular a conical cross section. The shape and the upper and lower end cross-sections of this part are chosen so that granular fuel with a given particle size spectrum is kept in a fluidized state under the influence of the gasifying agent fed in and also the gases rising from the fixed-bed gasification zone F.

The vessel G is closed and designed so that the gas generation can be carried out under increased internal pressure. But you can also work without increased pressure. If only the latter comes into consideration, the locks 6 and 13 can be omitted or replaced by other devices.

In the upper part of the generator vessel G , a cyclone 60 is arranged centrally, which works in the usual way on the principle of centrifugal force and serves to separate solid particles from the gas rising from the fluidized bed ^.

There may be an inlet device, not shown, through which the particles loaded gas enters cyclone 60. The product gas freed from the separated particles leaves the generator through an outlet connection 24 arranged in the central axis of the cyclone 60.

A device with a gasification chamber 70 is arranged under the cyclone 60, which is used for gasification of solid particles separated in the cyclone 60, this from the lower end of the cyclone 60 is used emerging particles collect in a settling space 61, which is essentially rotationally symmetrical Has basic shape and occupies the space above the gasification chamber 70 or the head part surrounds the gasification chamber. With the numeral 71 pipes of a cooling system are designated, which via a

A suitable coolant can be fed to inlet 72, which cools the tubes in the sense of the in FIG. 2 flows through the arrows shown and leaves the system via an outlet line 73. With the digit 62 is a coolant inlet door denotes a cooling system 63 belonging to the cyclone 60.

As can also be seen in FIG. 2, an oxygen supply line 64, which is surrounded by a cooling jacket 65 with an inlet and an oxygen supply line 64 for coolant, is guided from above to the gasification chamber 70 and is arranged centrally, ie it lies in the vertical longitudinal axis L the gasification chamber 70, which is essentially cylindrical in this embodiment. The oxygen supply line has at its end a head 66 which extends into the gasification chamber 70 and has outlet openings 80 through which the oxygen can pass into the gasification chamber.

The solid particles coming out of the cyclone and collecting in the settling space 61 are carried through evenly over the circumference of the gasification chamber 70 distributed inlets 74 introduced into the gasification chamber. With the one shown In the exemplary embodiment, each introduction 74 is designed in the manner of a Venturi nozzle 78, the axis 75 of which is directed secantially into the gasification chamber 70, as in particular FIG. 3 reveals. Besides, they are Inlets 74 inclined slightly with respect to the horizontal (FIG. 2). The entries 74 each have a connection 76 for a gaseous delivery medium, which is in particular at least partially an im Generator C is self-generated gas, which is used as a recirculation gas. This recirculation gas is in particular in the flow path behind a device for gas scrubbing, not shown taken, into which the product gas leaving the generator through the outlet nozzle 24 passes. To the Recirculation gas can also contain water vapor and /

Each inlet 74 has an inlet 77 for the particles to be gasified, which is located at the narrowest point the Venturi nozzle 78 is located and immediately with the overlying settling space 61 for the separated Particle communicates.

In the gasification process taking place in the generator G , the gasifying agents blown in, e.g. B. water vapor and oxygen, a chemical reaction with the introduced coal, in particular such that a gas is produced which consists primarily of hydrogen and carbon monoxide. This gas emerges from the fluidized bed W upwards and, in accordance with the exit speed, also takes along coal particles in the form of dust. These are separated in the cyclone 60 arranged above the fluidized bed W and collect in the settling space 61.

The hot dust separated in the cyclone, which consists partly of coal and partly of ash and is blown secantially into the gasification chamber 70 by the conveying medium through the inlets 74, whereby it receives a rotational movement, is by combustion with the supplied oxygen in a combustion zone of the supplied gas, namely recirculation gas, is further heated at the same time and then enters into chemical reactions with the surrounding gas components. The oxygen reacts spontaneously exothermically with part of the gas blown in, so that temperatures of, for example, 1600 "C to 180O ⁰ C can set in the gasification cart 70. The carbon content of the dust blown in with the conveying medium depends on the local state variables and the composition burn directly in part of the gas phase, and the remaining portion is reacted with the combustion products of the gas flame and possibly with excess steam according to the Bonduard reaction equation and the heterogeneous water gas equation.

At the same time, the ash components are brought into the liquid state. Through the secantial

ίο Injecting the conveying medium with the absorbed dust into the gasification chamber 70, not only the dust particles, but also the already liquefied slag droplets are set in a rotating motion, so that the slag droplets are carried by centrifugal forces to the wall of the gasification chamber, on which they are down to a lower one Run down collecting chute 79. The latter has one or more drainage openings, not shown, from which the liquid slag can drip down into the fluidized bed W on its way

λ) solidifies, passes through the fluidized bed and is finally discharged in solid form. As a result of the high-temperature gasification in the chamber 70, no dry ash particles occur which could be caught by the gas flow from the fluidized bed W and would have to be separated out again in the cyclone. The outlet of the chamber 70 is directed towards the fluidized bed W. This has the advantage, among other things, that the heat jet from the chamber 70 additionally heats the fluidized bed.

The F i g. 4 shows some details of the device on a larger scale, including the one below Head 66 located at the end of the oxygen supply line 64, which is surrounded by the cooling jacket 65 for example, twenty outlet openings 80 are provided. These advantageously have a relatively small cross section (z. B. a diameter of a few millimeters), so that nozzle-like outlet paths result. this is favorable for the formation of the flame in the gasification chamber 70. It can be in this way achieve that the oxygen at least at full

«O Operation of the device and thus the corresponding amount emerges at least at the speed of sound.

When the gasification chamber is put into operation, a combustible medium is initially expediently used Gas introduced externally (e.g. in a gas-powered recuperator) to a temperature above the ignition temperature with oxygen lying temperature has been heated. The temperature of that of the gasification chamber The supplied gas flow is measured and checked before it enters the chamber. Only when this gas flow has the specified temperature. becomes the supply of oxygen to the gasification chamber Approved.

In contrast to the embodiment shown, the generator can also be used only as a fluidized bed generator (Winkler generator), in which case FIG. 1 the lower part is unimaginable. In this case a suitable discharge device for the gasification residues is then available below the fluidized bed, z. B. a liquid slag discharge.

There are various options for the structural design and the arrangement of the cyclone with the post-gasification device. This also applies to the mounting, support or suspension of the cyclone in the generator and to the arrangement and attachment of the lines for the various media. Suitable construction elements are available to those skilled in the art for this purpose.
The invention also includes an embodiment

tion, in which the cyclone is not arranged inside a generator, but outside of the Generator vessel is located. In such and similar designs, in which the rising from the fluidized bed Gas flow through suitable Leituingswege in the

10

Cyclone is introduced, however, the gasification chamber is at least partially, advantageous but in their entirety, within the generator vessel in question, always in such a way that you Exit is directed towards the fluidized bed.

For this purpose 3 sheets of drawings

Claims (17)

Patent claims: 1. A process for generating gas from solid fuels with gasification agents in a fluidized bed, from which the residues are discharged below and in which the solids contained in the gas rising from the fluidized bed are separated by centrifugal force and operated in a side reaction operated separately from the fluidized bed by separately supplied gasification agents nachvergast fluid bed and the Schlackenschrnelztemperatur excess temperature and the reaction products formed are fed to the fluidized bed, wherein the solids are deposited within the generator above the fluidized bed and nachvergast immediately and all Nachvergasungsprodukte be passed directly into the fluidized bed where ^K ei is the melt in the fluidized bed - and optionally in a fixed bed located below - cools down to solidification, according to patent 27 42 222, characterized in that the particles separated in the cyclone are collected and removed from this collection by means of a it gaseous conveying medium in the separate gasification area, with generation of an at least partially rotating movement or circulation movement in this, are transported and that oxygen is introduced spatially separated from the conveying medium into the gasification area. 2. The method according to claim 1, characterized in that that the FöivJermec; <im with him absorbed particles is introduced essentially secantially into the gasification area. 3. The method according to any one of claims I and 2, characterized in that the delivery medium at least partially a gas generated in the process is used as recirculation gas. 4. The method according to any one of claims 1 to 3, characterized in that the delivery medium Water vapor is added. 5. The method according to any one of claims 1 to 4, characterized in that carbon dioxide is added to the delivery medium. 6. The method according to any one of claims 1 to 5, characterized in that the amount of in the Oxygen introduced into the gasification area versus the amount of gas offered in the gasification area is set substoichiometric. 7. Device for use in generating gas from solid fuels by means of fluidized beds or Fluidized bed and fixed bed gasification in one Feeds for the fuel and for the gasification agent having generator vessel, with a cyclone for separating particles from the Fluidised bed ascending gas and with a gasification chamber assigned to the cyclone with gasifying agent feed line for the gasification of particles deposited in the cyclone, in particular for Implementation of the method according to one of claims 1 to 6, characterized in that the Gasification chamber (70) at least one inlet (64, 66) for oxygen and at least one thereof separate inlet (74) for a conveying medium laden with the particles separated in the cyclone (60) contains, wherein the introduction (74) at least one connection (76) for the conveying medium, at least one in the path of the pumped medium! Has an inlet (77) for the separated particles and an outlet (78) directed essentially secantially into the gasification chamber (70) 8. Apparatus according to claim 7, characterized in that that with several introductions (74) these regularly over the circumference of the gasification chamber (70) are arranged distributed. 9. Device according to one of claims 7 and 8, characterized in that the introduction (74) is arranged below a settling space (61) for the separated particles, the inlet (77) the introduction (74) is in communication with the settling space (61). 10. Device according to one of claims 7 to 9, characterized in that the introduction (74) is arranged inclined to the horizontal. 11. Device according to one of claims 7 to 10, characterized in that the introduction (74) is designed as a Venturi nozzle (78), the inlet (77) for the separated particles on the the narrowest point of the Venturi nozzle. IZ device according to one of Claims 7 to 10, characterized in that the introduction (74) is designed as an injector. 13. Device according to one of claims 7 to 12, characterized by an oxygen inlet (64, 66) arranged essentially in the region of the longitudinal center axis (L) of the gasification chamber (70). 14. Device according to one of claims 7 to 13, characterized by one provided with several, relatively small outlet openings (80) Head (66) or the like for introducing oxygen into the gasification chamber (70). 15. Device according to one of claims 7 to 14, characterized by an oxygen supply line leading from above to the gasification chamber (70) (64). 16. Device according to one of claims 7 to 15, characterized by an oxygen supply line (64) provided with cooling (65). 17. Device according to one of claims 7 to 16, characterized in that a collecting channel (79) at the lower end of the gasification chamber (70) Od. Like. Is intended for slag.