WO2003064950A1 - Methods and devices for heating a continuous flow of solids - Google Patents

Abstract

A pneumatically conveyed flow of solids is continuously introduced into a pressurized container (42) in which a fluidized bed is maintained by adding an aerating gas, said bed being heated by heat exchange with a heat transfer medium (58). The mixture of solid/gas is continuously removed from the fluidized bed and separated into a lean gas phase and a highly compressed solid /gas mixture by gravitational or centrifugal deposition. The highly compressed solid/gas mixture is then continuously discharged into a pneumatic conveyor line (221) and conveyed pneumatically. The solid content of the pressurized container (42) is continuously monitored. Via a controlled gas removal (68) from the lean gas phase the continuos discharge of the highly compressed solid/gas mixture into the pneumatic conveyor line (221) is controlled in such a manner that the solid content of the pressurized container (42) remains substantially constant.

Description

 Methods and apparatus for heating a continuous stream of solids

The present invention relates to a method for heating a continuous flow of solids and devices for carrying out this method.

State of the art

Pneumatically conveyable solids such as e.g. Coal dust to be heated in a fluidized bed heat exchanger. Such

Fluidized bed heat exchangers comprise a columnar pressure vessel in which a bed of solid particles is flowed through from below by a loosening gas. In the bed, the solid particles are carried by the upward loosening gas, so that a so-called fluidized bed is maintained. The fluidized bed is heated by heat exchangers which are immersed in or surround the fluidized bed.

Such a fluidized bed heat exchanger is described in WO 99/24773. The solid to be heated is transported to the heat exchanger in a pneumatic conveyor line and continuously fed into the fluidized bed at the lower end of the heat exchanger. At the upper end of the heat exchanger, the fluidized bed flows into a discharge device for the solid. The latter includes a rotary valve that continuously discharges the solid. The gas that accumulates at the upper end of the heat exchanger is drawn off in such a way that there is a constant overpressure in the heat exchanger. The extracted gas is cleaned in a cyclone.

In many processes there is a need to remove the solid after it

Pneumatically transfer heating in the fluidized bed heat exchanger.

It would therefore be of advantage if a heated solid / gas mixture was transferred directly from the fluidized bed heat exchanger into a pneumatic one

Could initiate delivery line. However, it has been found that this procedure, a stable pneumatic delivery does not necessarily achieve. This seems to be primarily due to the fact that the solid / gas mixture withdrawn from the fluidized bed can have highly variable solids loading. When blowing coal dust into a blast furnace, there is today

Requires to heat the coal dust to temperatures above 200 ° C before blowing it into the blast furnace. Here, the coal dust loses a large part of its pore moisture, which releases relatively large and highly variable amounts of water vapor. When heated to temperatures above 200 ° C, the gas phase, which includes the released water vapor, the conveying gas and the loosening gas, expands greatly. In order to be able to pneumatically transport the coal dust heated in the fluidized bed heat exchanger without any problems, until now the heated material flow from the fluidized bed had first to be discharged via a lock device into a degassing container from which the gas phase was drawn off. The coal dust is then discharged from this degassing container into a fluidization device, which feeds it into a pneumatic conveying line, the mass flow rate of the coal dust in the pneumatic conveying line being regulated. The degassing tank with entry lock, the fluidization device and the mass flow control device naturally cause the plant to become significantly more expensive.

Object of the invention

It is an object of the present invention to propose a method by means of which a continuous stream of solids can be heated and immediately conveyed pneumatically, with sufficient stability of the pneumatic conveying having to be ensured.

Summary of the invention

A pneumatically conveyable solid stream is continuously fed into one Pressure vessel entered, in which a fluidized bed is maintained by adding a loosening gas, which is heated by heat exchange with a heat transfer medium. According to the invention, a solid / gas mixture is continuously removed from the fluidized bed and divided into a weakly laden gas phase and a highly compressed solid / gas mixture by gravity or centrifugal separation. The highly compressed solid / gas mixture is then continuously discharged into a pneumatic conveying line and pneumatically conveyed there. The solids content of the pressure vessel is continuously monitored. The continuously discharging of the highly compressed solid / gas mixture into the pneumatic conveying line is regulated in such a way that the solids content of the pressure vessel always remains largely constant via a regulated gas discharge from the weakly laden gas phase. With this method, a continuous flow of solids can be heated and conveyed pneumatically immediately, with good stability of the pneumatic conveying being guaranteed.

The proposed method is suitable e.g. Excellent for heating and drying a pneumatically conveyable solid that has bound water to it due to hygroscopicity. Here, the solid in the fluidized bed is heated such that a large part of this water evaporates in the fluidized bed and passes into the gas phase. It should be noted that the proposed method makes it possible to subsequently convey the heated solid immediately pneumatically, while ensuring good stability of the pneumatic conveyance, which was previously considered impossible.

For example, the proposed method can advantageously be applied to coal dust that has been dehumidified in front of the pressure vessel at a temperature of less than 100 ° C., so that its surface moisture is negligible when it enters the fluidized bed, but its pore moisture is still relatively high. This coal dust loses most of its pore moisture in the fluidized bed at temperatures between 150 ° C and 250 ° C. The proposed method makes it possible for the strongly heated Transporting coal dust directly pneumatically, whereby a good stability of the pneumatic conveying is guaranteed, which was previously considered impossible.

In an advantageous embodiment, the pressure vessel comprises a fluidized bed heat exchanger and a degassing column. The solid stream is continuously introduced into the fluidized bed heat exchanger at the lower end. In this fluidized bed heat exchanger, a fluidized bed is maintained by adding a loosening gas, which is heated by heat exchange with a heat transfer medium. At the upper end of the fluidized bed heat exchanger, a heated solid / gas mixture flows from the fluidized bed into the degassing column. Here the overflowed solid / gas mixture forms a fluidized bed which is highly compressed under the influence of gravity, the separated gas phase accumulating in the upper end of the degassing column. The highly compressed fluidized bed is continuously discharged into the pneumatic delivery line at the lower end of the degassing column. This continuous discharge of the highly compressed fluidized bed into the pneumatic delivery line is controlled via a regulated gas outlet at the upper end of the degassing column. The highly compressed fluidized bed can be loosened at the lower end of the degassing column by adding a gas before it is discharged into the pneumatic delivery line. In this embodiment, a change in the solids content is advantageously detected by a change in the height of the highly compressed fluidized bed in the degassing column.

In a further advantageous embodiment, the pressure vessel only comprises a fluidized bed heat exchanger. The solid stream is continuously introduced into the fluidized bed heat exchanger at the lower end. In this fluidized bed heat exchanger, a fluidized bed is maintained by adding a loosening gas, which is heated by heat exchange with a heat transfer medium. A heated solid / gas mixture is removed from the top of the fluidized bed via a cyclone, the cyclone removing the removed solid / gas mixture by centrifugal force into a weakly laden gas phase and a highly compressed solid / gas mixture divides. The highly compressed solid / gas mixture is continuously fed into the pneumatic delivery line. The throughput of the solid / gas mixture into the pneumatic delivery line is controlled via a regulated gas discharge in the cyclone. In this embodiment, a change in the solids content is advantageously detected by a change in the height of the fluidized bed in the fluidized bed heat exchanger.

Advantageous devices for executing these process variants are also presented.

piece placement

Various configurations of the invention will now be described below with reference to the accompanying figures. Show it:

1: a simplified system diagram of a coal dust injection for a blast furnace, with a first embodiment of a device according to the invention for heating the pneumatically conveyed coal dust;

FIG. 2: an enlarged detail from FIG. 1, which shows the structure of the device for heating a pneumatically conveyed solid in a schematic longitudinal section;

3 shows a schematic longitudinal section through a second embodiment of a device according to the invention for heating a pneumatically conveyed solid; 4 shows a cross section along the section line 4-4 'of FIG. 3; and

5: an enlarged detail from FIG. 3.

Description of preferred embodiments of the invention with reference to the figures

Fig. 1 shows a highly simplified scheme of a

Coal dust injection for a blast furnace 10. A bracket with the

Reference numeral 12 designates a plant for the processing of coal dust globally. This system 12 comprises, in a known manner, one

Storage bunker 14, a lock container 16 and an injection container 18. The coal dust 20 is stored in the storage bunker 14 and, if necessary, dehumidified at temperatures below 100.degree. A plurality of pneumatic delivery lines 22 1, 22 ₂ , 22 ₃ , 22, ... are connected to this blowing container 18. Each of these pneumatic delivery lines 22ι, 22 ₂ , 22 ₃ , 22, ... in this case supplies a blow mold 24ι of the blast furnace 10, in which the coal dust is blown into the blast furnace 10. To regulate the mass flow rate of the coal dust, each pneumatic delivery line 22ι, 22 ₂ , 22 ₃ , 22, ... comprises a control device 26ι. In Fig. 1, this control device 26ι is shown in the pneumatic delivery line 22i by a mass flow meter 28 and a flow control valve 30. It should also be emphasized that the coal dust in the pneumatic conveying lines 22ι, 22 ₂ , 22 ₃ , 22 ₄ , ... is preferably transported in a dense stream, so that gas and energy consumption and wear are minimized. Dense phase conveying is understood to mean a solids loading of at least 20 kg of solids per kg of conveying gas.

The reference numeral 40 shows a device for heating the pneumatically conveyed coal dust, which is built into the pneumatic conveying lines 22ι (the section of the pneumatic conveying line 22ι downstream of the device 40 is provided with the reference number 22'ι). This device 40 is intended to heat the coal dust, which is conveyed in the pneumatic delivery line 22ι, 22'ι, to temperatures between 150 ° C. and 300 ° C. before blowing into the blast furnace 10.

The device 40 from FIG. 1 will now be described in more detail with reference to FIG. 2. It comprises two columnar pressure vessels 42, 44, the first pressure vessel 42 forming a fluidized bed heat exchanger and the second pressure vessel 42 forming a degassing column. It should be emphasized that each of the two columnar pressure vessels 42, 44 has a height of several meters.

The fluidized bed heat exchanger 42 has in its lower end a fluidization device 46 with a gas connection 48 for

Loosening gas. Such a fluidization device 46 includes, for example a porous fluidization tray 50 known per se, via which the loosening gas (in the case of coal dust it is preferably an inert gas such as nitrogen) is distributed uniformly over the entire cross section of the columnar pressure vessel 42. Via a solids inlet device 52, the coal dust is introduced from the pneumatic delivery line 22ι directly above the fluidization tray 50 into the pressure vessel 42. The loosening gas flowing in via the porous fluidization base 50 carries the solid particles upwards. A fluidized bed 54 is formed in the columnar pressure vessel 42, which has liquid-like properties. This fluidized bed 54 extends from the fluidization base 50 to a cross connection 56 which connects the two columnar pressure vessels 42, 44 at their head ends. Through this cross-connection 56, the solid / gas mixture flows from the fluidized bed 54 into the second pressure vessel 44. In a continuous operating state, the solids mass throughput in the cross connection 56 corresponds to the solids mass throughput in the pneumatic conveying line 22. A fluidized bed 54 of several meters in height is therefore maintained in the first pressure vessel 42, in which the coal dust particles slowly move from bottom to top , This fluidized bed 54 is heated by a heat exchanger, which is formed by a double-walled jacket 58 in FIG. 2. This jacket heat exchanger 58 surrounds the fluidized bed 54 over most of its height and is flowed through from top to bottom by a heat transfer medium, normally a heat transfer oil. The fluidized bed heat exchanger 42 is preferably designed such that

Temperatures and dwell times in the fluidized bed 54 are achieved, which ensure that the majority of the pore moisture of the coal dust in the fluidized bed 54 evaporates. This is normally achieved at temperatures of 150 ° C to 250 ° C, residence times of 2 to 4 minutes and a pressure in the pressure vessel of approximately 6 to 8 bar. It can be assumed that between 0.05 and 0.1 kg of water vapor is released per kg of coal dust, which is at a pressure of 8 bar and a temperature of 200 ° C corresponds to a gas volume between 0.012 to 0.024 m ³ per kg of coal dust.

In the second column-shaped pressure vessel 44, which forms the degassing column, the solid / gas mixture overflowing from the fluidized bed 54 through the cross-connection 56 is strongly compressed under the influence of gravity. In this case, a strongly compressed fluidized bed 60 is formed in the degassing column 44, the separated gas phase accumulating in the upper end 62 of the degassing column 44. At the lower end, the degassing column 44 has a discharge device 64 for the continuous discharge of the highly compressed fluidized bed 60 into the pneumatic delivery line 22 '. This discharge device 64 advantageously comprises a gas-loosening device 66 which loosens the highly compressed fluidized bed 60 before it is discharged into the pneumatic conveying line 22 '. The continuous discharge of the highly compressed fluidized bed 60 from the degassing column 44 into the pneumatic delivery line 22 ¹ _! is regulated here via a regulated gas vent 68 at the upper end 62 of the degassing column 44 such that the solids content of the device 40 remains largely constant. For this purpose, the regulated gas outlet 68 has a regulating valve 70, a regulator 72 and a measuring probe 74. The measuring probe 74 detects a change in the height of the strongly compressed fluidized bed 60 in the degassing column 44. Capacitive level meters or microwave level meters are suitable as measuring probe 74, for example. As the height of the highly compressed fluidized bed 60 increases, the controller 72 causes less gas to be drawn off via the control valve 70. As a result, the gas pressure in the degassing column 44 increases, and the discharge device 64 discharges more coal dust into the pneumatic delivery line 22 ′. When the height of the highly compressed fluidized bed 60 decreases, the controller 72 causes more gas to be drawn off via the control valve 70. As a result, the gas pressure in the degassing column 44 drops and the discharge device 64 discharges less coal dust into the pneumatic delivery line 22. This regulation thus ensures that the solids flow of the is continuously discharged from the device 40, corresponds to the solid flow which is continuously introduced into the device 40. In this way, a stable dense phase flow of the coal dust can be achieved in the pneumatic delivery line 22 ′ downstream of the device 40. The gas drawn from the upper end 62 of the degassing column 44 can, as shown in FIG. 1, be returned via a line 76 to the storage bunker, where it contributes to preheating the coal dust before it is discharged into the atmosphere via a filter device 78.

A device 140 for heating a pneumatically conveyed solid is now described with reference to FIGS. 3 to 5, which represents an interesting alternative to the device 40 from FIG. 1, since it only comprises a columnar pressure vessel 142. The latter also has a height of several meters and forms a fluidized bed heat exchanger. The columnar pressure vessel 142, like the columnar pressure vessel 42, has a fluidization device 146 with a gas connection 148 for a loosening gas in its lower end. Such a fluidization device 146 comprises, for example, a porous fluidization base 150 known per se, via which the loosening gas, in the case of coal dust, is preferably an inert gas, such as nitrogen, is uniformly distributed over the entire cross section of the columnar pressure vessel 142. Via a solids inlet device 152, the coal dust from the pneumatic conveying line 22-ι, which comes from the system 12 for the processing of the coal dust, is introduced into the pressure vessel 142 immediately above the fluidization tray 150. The loosening gas flowing in through the porous fluidization base 150 carries the solid particles upwards. A fluidized bed 154 is formed, which extends in the columnar pressure vessel 142 from the fluidization base 150 to the upper end of the pressure vessel 142. Accordingly, a fluidized bed 154 with a height of several meters is maintained in the pressure vessel 142, in which the coal dust particles slowly move from bottom to top. This fluidized bed 154 is heated by a heat exchanger, which is formed by a double-walled jacket 158 in FIG. 3 becomes. This jacket heat exchanger 158 surrounds the fluidized bed 154 over most of its height and is flowed through from top to bottom by a heat transfer medium, normally a heat transfer oil. Like the fluidized bed heat exchanger 42, the fluidized bed heat exchanger 142 is preferably designed in such a way that temperatures and residence times are achieved in the fluidized bed 154, which ensure that the majority of the hygroscopically bound water evaporates in the fluidized bed 154.

At the upper end of the fluidized bed 154, a heated solid / gas mixture is withdrawn from the fluidized bed 154 via a cyclone 161, the removed solid / gas mixture being divided by centrifugal force into a weakly laden gas phase and a highly compressed solid / gas mixture , The cyclone 161 is advantageously arranged within the columnar pressure vessel 142, wherein it has an inlet 163 for the removal of a solid / gas mixture from the fluidized bed 154, a first outlet 165 for a compressed solid / gas stream and a second outlet 167 for the weakly laden gas stream. The first outlet 165 and the second outlet 167 are led out of the columnar pressure vessel 142 in a pressure-tight manner. It should be noted that the cyclone 161, due to its arrangement within the pressure vessel 142, does not itself have to be designed as a pressure vessel.

The first outlet 165 of the cyclone 161 opens directly into the pneumatic conveying line 22 ′ leading to the blast furnace 10. A strongly compressed solid / gas mixture is thus continuously introduced into the pneumatic delivery line 22 ′ via this first outlet 165. The throughput of the highly compressed solid / gas mixture into the pneumatic delivery line 22 ′ is regulated here via a regulated gas discharge through the second outlet 167 of the cyclone 161 in such a way that the total solid content of the device 140 remains largely constant. For this purpose, the second outlet 167 has a control element 170 designed as a throttle device for the controlled removal of a weakly laden gas stream from the cyclone 161. This regulator 170 forms with a regulator 172 and a measuring probe 174 a control loop. The measuring probe 174 detects a change in the height of the fluidized bed 154. As this height increases, the controller 172 throttles the second outlet 167 via the throttling device 170, so that less gas is drawn off above the cyclone 161. This increases the gas pressure, which causes an increase in the mass flow rate in the first outlet 165 of the cyclone 161. When the height of the fluidized bed 154 decreases, the controller 172 reduces the throttling of the second outlet 167 via the throttle device 170, so that more gas is drawn off above the cyclone 161. As a result, the gas pressure in the cyclone 161 drops, which causes a reduction in the mass flow rate in the first outlet 165 of the cyclone 161. This regulation thus ensures that the solid stream that is continuously discharged from the device 140 corresponds to the solid stream that is continuously fed into the device 140. In this way, a stable pneumatic conveying of the coal dust can be achieved in the pneumatic conveying line 22 ′, ie downstream of the device 140.

An advantageous embodiment of the cyclone 161 will now be described with reference to FIGS. 4 & 5. The latter comprises a separation chamber 180 with a tangential inlet chamber 182, which forms the inlet 163 in the fluidized bed 152. The separation chamber 180 tapers conically downwards and merges into the first outlet 165. It is connected via a pipe 184 to a flange 186 which is fastened in a gas-tight manner on a counter flange 188 of the pressure vessel 142. The second outlet 167 is arranged centrally in the deposition chamber 180. It is formed by a vertically displaceable inlet connector 200 which extends through the pipe 184 and is led out of the pressure vessel 142 in a sealed manner. The vertical displacement of the inlet connection 200 takes place via an actuator 202 arranged outside the pressure container 142 (see FIG. 3). Reference number 204 denotes a fixed closure body which projects centrally into the lower outlet of the inlet connector 200. Here it interacts with a reduced through opening 206 of the inlet connector 200 such that, depending on the vertical position of the inlet connector 200, the Closure body 204 more or less constricts the through-opening 206, ie more or less throttles the second outlet 167.

It should be noted that the height measurement of the fluidized bed 54, 154 described herein is most likely the easiest way to determine a change in the solids content in the devices 40 and 140. If necessary, it can be refined by one or more density measurements of the fluidized bed 54, 154. However, it is not outside the scope of the present invention to change the solids content of the devices 40 and 140 by other measurement methods, such as e.g. a weight measurement.

Claims

claims 1. A method of heating a continuous stream of solids, wherein: a stream of solids is continuously fed into a pressure vessel; a fluidized bed is maintained in this pressure vessel by adding a loosening gas; and the fluidized bed is heated by heat exchange with a heat transfer medium; characterized in that a solid / gas mixture is continuously removed from the fluidized bed and by gravity or centrifugal separation into a weakly laden gas phase and a highly compressed solid / gas Mixture is divided; that the highly compressed solid / gas mixture is continuously discharged into a pneumatic conveying line and pneumatically conveyed there; that the solids content of the pressure vessel is continuously monitored and that the continuous discharge of the highly compressed solids / gas mixture into the pneumatic delivery line is regulated via a regulated gas discharge from the weakly laden gas phase in such a way that the solids content of the pressure vessel remains largely constant. 2. The method of claim 1, wherein: with an increase in the solids content of the pressure vessel, less gas is withdrawn from the weakly laden gas phase; and with a decrease in the solids content of the pressure vessel, more gas is withdrawn from the weakly laden gas phase. 3. The method according to any one of claims 1 to 2, wherein the solid has bound water to itself by hygroscopicity, and wherein the solid in The fluidized bed is heated in such a way that a large part of this water evaporates in the fluidized bed and passes into the gas phase. 4. The method of claim 3, wherein: the solid is a coal dust that has been dehumidified in front of the pressure vessel at a temperature of less than 100 ° C so that its Surface moisture when entering the fluidized bed is negligible, but its pore moisture is still relatively high; and the coal dust in the fluidized bed loses most of its pore moisture at temperatures between 150 ° C and 250 ° C. 5. The method according to any one of claims 1 to 4, wherein: the pressure vessel comprises a fluidized bed heat exchanger and a degassing column; the solid stream is continuously introduced into the fluidized bed heat exchanger at the lower end; in this fluidized bed heat exchanger by adding a Loosening gas a fluidized bed is maintained; the fluidized bed is heated by heat exchange with a heat transfer medium; at the upper end of the fluidized bed heat exchanger, a heated solid / gas mixture flows from the fluidized bed into the degassing column; the overflowed solid / gas mixture in the degassing column forms a fluidized bed which is strongly compressed under the influence of gravity, the separated gas phase accumulating in the upper end of the degassing column; the highly compressed fluidized bed at the lower end of the degassing column is continuously discharged into the pneumatic delivery line; and the continuous discharge of the highly compressed fluidized bed into the pneumatic delivery line via a regulated gas outlet on the top End of the degassing column is controlled. 6. The method of claim 5, wherein: the highly compressed fluidized bed is loosened at the lower end of the degassing column by adding a gas before it is discharged into the pneumatic delivery line. 7. The method of claim 5 or 6, wherein: a change in the height of the highly compressed fluidized bed is detected in the degassing column; as this height increases, less gas is withdrawn from the top of the degassing column; and as this level decreases, more gas is withdrawn from the top of the degassing column. 8. The method according to any one of claims 1 to 4, wherein: the pressure vessel comprises a fluidized bed heat exchanger; the solid stream flows continuously into the bottom Fluidized bed heat exchanger is introduced; a fluidized bed is maintained in this fluidized bed heat exchanger by adding a loosening gas; the fluidized bed is heated by heat exchange with a heat transfer medium; a heated solid / gas mixture is removed from the fluidized bed at the top via a cyclone, the cyclone dividing the removed solid / gas mixture into a weakly laden gas phase and a highly compressed solid / gas mixture by centrifugal force; the highly compressed solid / gas mixture is continuously introduced into the pneumatic delivery line; and a regulated gas discharge in the cyclone controls the throughput of the solid / gas mixture into the pneumatic delivery line. 9. The method of claim 8, wherein: a change in the height of the fluidized bed is detected in the fluidized bed heat exchanger; as this height increases, less gas is withdrawn from the cyclone; and as this level decreases, more gas is withdrawn from the cyclone. 10. The method according to any one of claims 8 or 9, wherein the cyclone is arranged in the fluidized bed. 11. The method according to any one of claims 8 to 10, wherein: the cyclone has an adjustable nozzle for the removal of the weakly laden gas stream. 12. An apparatus for performing the method according to one of claims 5 to 7, comprising: a first column-shaped pressure vessel (42), with a lower end and an upper end, which forms the fluidized bed heat exchanger and comprises at least the following parts: a feed (52) for a solid stream in the lower end of the first columnar pressure vessel (42); a fluidizing device (46) in the lower end of the first columnar pressure vessel (42) for maintaining a fluidized bed (54) in the first columnar pressure vessel (42); a heat exchanger (58) for heating the fluidized bed (54); a second column-shaped pressure vessel (44) with a lower end and an upper end, which forms the degassing column and comprises at least the following parts: a discharge device (64) at the lower end of the degassing column (44), for the continuous discharge of the highly compressed fluidized bed (60 ) in the pneumatic delivery line (22'τ); and a controllable gas extraction device (68) at the upper end of the degassing column (44) for controlled gas extraction of the gas stream from the weakly laden gas phase; and a connection (56) between the two upper ends of the two columnar pressure vessels (42 and 44) so that the solid / gas Mixture at the upper end of the fluidized bed heat exchanger (42) can flow from the fluidized bed (54) into the degassing column (44). 13. The apparatus of claim 12, comprising: a measuring probe (74) for measuring the height of the highly compressed fluidized bed (60) in the degassing column (44); and a control circuit for controlling the controllable gas extraction device (68) as a function of the measured height of the highly compressed fluidized bed (60) in the degassing column (44). 14. The apparatus of claim 12 or 13, wherein the discharge device comprises a gas loosening device (66). 15. The apparatus for performing the method of any one of claims 8 to 11, comprising: a columnar pressure vessel (142) having a lower end and an upper end; a feed (152) for a solid stream in the lower end of the columnar pressure vessel (142); a fluidizing device (146) in the lower end of the columnar pressure vessel (142) for maintaining a fluidized bed (154) in the columnar pressure vessel (142); a heat exchanger (158) for heating the fluidized bed (154); and a cyclone (161) disposed in the upper end of the columnar pressure vessel (142), having an inlet (163) for withdrawing a solid / gas mixture from the fluidized bed (154), a first outlet (165) for one compressed solid / gas flow and a second outlet (167) for a weakly laden gas stream, the first and second outlets (165, 167) being led out of the column-shaped pressure vessel (142) in a pressure-tight manner, and the second outlet (167) having a regulating member (170) for the controlled discharge of a weakly laden gas stream having. 16. The apparatus of claim 15, comprising: a measuring probe (174) for measuring the height of the fluidized bed (154) in the degassing column; and a control circuit for regulating the control element for the removal of the weakly laden gas stream as a function of the height measured by the measuring probe (174). 17. The apparatus of claim 15 or 16, wherein the cyclone comprises the following parts: a separation chamber (180) with a tangential inlet chamber (163) which forms the inlet in the fluidized bed (154), the separating chamber (180) tapers conically downwards and merges into the first outlet (165), and the second outlet (167) is arranged centrally in the separation chamber (180). 18. The apparatus of claim 17, wherein the control member (170) is designed as a throttle device in the input of the second outlet (167). 19. The apparatus of claim 18, wherein the throttle device is formed by a fixed, central closure body (204) and a vertically displaceable inlet connector (200) with a reduced through opening (206), and the closure body (204), depending on the vertical position of the inlet connector (200) who Through opening (206) more or less constricts.