EP0625562B1 - Process for gasification of solid substances and gasification reactor - Google Patents

Abstract

Solids (esp. residue) gasification process involves (partially) gasifying the solids in a shaft with controlled sub-stoichiometric supply of fresh air and feeding the incompletely gasified solids and gases via one or more narrow points of the shaft to a chamber in which the solids are post-gasified and from which the gases are withdrawn, a bed being formed from which ash is discharged.

Description

The invention relates to a method for gasification and Burning of solids, especially residues, with the features of the preamble of claim 1 and a gasification reactor with the features of the preamble of claim 8.

Methods of this kind are complicated by the fact that Gasification of the solids to be burned, usually lumpy organic solids, such as wood, plastic, Rubber, packaging material, textile, paper waste, e.g. in the form of chops, pellets, briquettes or the like, takes a long time compared to the previous degassing many times over. In addition to this difficulty that partially gasified solids, which over the Narrowed into the chamber for further gasification are, partly in the developing at the bottom of the chamber Ash bed fall and from there burned incompletely are carried out with the ashes. This worsens the gas yield. If the gasification process after the ash has been discharged outside the gasification reactor continues, gases are formed which are due to the existing environmental protection regulations are not easy can be drained into the environment.

In addition, these regulations must ensure that that organic matter to be deposited in Residues less than 5%.

In a known method and a known gasification reactor according to DE 39 24 626 C2 is to be avoided of these disadvantages additionally air in the range of Ash bed initiated, which is also from a movable support in the form of a horizontal Axis pivotable prism is formed. In this way a complete should be in the chamber below the narrow point Combustion of only partially gasified and burned solids can be achieved. The length Gasification time can hardly be shortened by these measures and the gas yield improves in usually not because that which is driven out of the solids Gas is not discharged but on the spot burns. In addition, in such a known "descending" working process in which the solids and the introduced air flows from top to bottom, a bad "burnout" is known, so that in the removed Ash still unburned residual portions of the Solid matter is included, which is disposed of at a landfill Need to become.

The known construction also calls for both the space requirement as well as the structural design considerable effort.

The invention has for its object a method and a gasification reactor of the type described above Art to train so that with a more compact design Period of gasification significantly shortened and at the same time the gasification yield can be optimized.

A method according to claim serves to solve this problem 1.

A gasification reactor according to the invention stands out by the features of claim 8.

With the method according to the invention it is achieved that fallen into bed, not yet fully gassed or burned solids by means of the fluidizing and reaction gas in the formed according to the invention Fluidized bed brought into suspension and on all sides be enveloped by gas. Through the reaction gas, which contains oxygen components become such solid components in a much shorter time period completely gasified up to the (short) degassing time as if the solids content in a solid bed or in the ash bed. So the gasification rate and the yield of gases is significantly improved. The gases produced are removed from the gasification reactor and in a separate Combustion process to generate useful heat burned. Alternatively, they can be at least partially back in the shaft to support the Ent- and Gasification of the solids are introduced.

In the invention, the unburned residual portions are in a negligible size. Surrender therefore no environmental problems, because only completely from Free carbon and polluting ingredients Ash is to be disposed of.

In a first embodiment of the method according to Invention is the fluidizing chamber or a fluidized bed in the Shaft designed in-house, namely in the ash bed. At A fluidization chamber is a second embodiment of the invention separately below or next to the shaft educated. In a gasification reactor according to the invention in this case the shaft is through a wall of separated from the fluidizing chamber, which run horizontally can and then represents a partition, or vertically can be formed by a side wall of the shaft, then a passage for connecting the in sub-rooms divided fluidizing space is left.

Further embodiments of the invention are in the subclaims put under protection.

Fig. 1 bis 5

fünf Varianten des Vergasungsreaktors gemäß der Erfindung im Vertikalschnitt, wobei der Einfachheit halber für gleiche oder gleichwirkende Bauteile oder Baugruppen gleiche Bezugszahlen verwendet sind und

Fig. 6

einen Längsschnitt durch ein Düsenrohr in einem Boden eines Vergasungsreaktors gemäß der Erfindung und

Fig. 7

eine weitere Variante eines erfindungsgemäßen Vergasungsreaktors.

The invention is explained in more detail below with reference to schematic drawings of exemplary embodiments. Show it:

1 to 5

five variants of the gasification reactor according to the invention in vertical section, the same reference numbers being used for the same or equivalent components or assemblies for the sake of simplicity and

Fig. 6

a longitudinal section through a nozzle tube in a bottom of a gasification reactor according to the invention and

Fig. 7

a further variant of a gasification reactor according to the invention.

The gasification reactor shown in Fig. 1 according to the invention has a vertical shaft 1 with an upper one Opening 3, through which, for example, by means of a rotary valve 5-piece, carbon-containing solids such as wood, plastic, rubber, paper and textile waste and the like can be introduced.

The solids form a solid bed 7 in the upper Part of the shaft 1 up to a support 9 in the form a prism which is pivotable about a pivot axis 11 and in the middle of its prismatic roof 13 has a rigid sheet metal plate 15, which for loosening the solid bed 7 and for the closure of any in the gas channels formed in the bed at one Pivoting movement of the prism 9 about the pivot axis 11 serves. The prism 9 forms bottlenecks on both sides 17, 19 to the shaft inner walls 21, 23, so that with an oscillating pivoting movement of the prism 13 Solid content through the narrow points 17, 19 down can be transported into a chamber 25 in the shaft 1.

The gasification of the solid bed above the bottlenecks 17, 19 is by supplying fresh air through nozzles 18, 20 required, and in an amount that one substoichiometric proportion of oxygen based on the corresponds to the amount of gas generated in the solid bed. The nozzles 18, 20 penetrate the shaft side walls at different heights in the upper part of the Shaft and can shape the shaft circumference in each case of nozzle rings with equally spaced nozzles surround.

In the chamber 25, the degassing from the narrow points 17, 19 failed solid parts continued. The chamber 25 becomes a side tube 27 the gas generated together with dust or ash parts withdrawn and fed to a cyclone, not shown, where Dust and ash are separated off centrifugally while the gas of a combustion in a separate process is supplied to generate useful heat.

An ash bed forms in the lower area of the shaft 29, in which also not fully gassed Solid particles fall into it. In this ashes or Fluidizing bed 29 opens laterally from a feed pipe 31, by means of which a screw conveyor 33 first a basic filling with a fine-grained inert Material, such as sand or ash, and that in operation the cyclone mentioned is deposited material, and if necessary, additional organic fine-grained material is conveyed into it becomes.

The proportion of organic material should preferably be overall not more than 3%.

The bottom 35 of the fluidizing bed 29 is made of nozzle pipes 37 interspersed, of which one in greater detail Scale is shown in Fig. 6 in longitudinal section. According to 6, each nozzle tube 37 is formed by a piece of tube, which is closed at the top by a lid 39. In the part of the Pipe piece 37 are inclined downwards from the inside to the outside Nozzle holes 41 are provided. The nozzle bores 41 are thus directed downward into the fluidizing bed 29. Because of this construction of the nozzle tube there is an outflow of inert material from the fluidizing bed 29 in a arranged under the floor 35 Gas chamber 43 avoided, which is below the shaft 1 on Floor 35 is attached. The gas chamber 43 has a lateral one Gas inlet 45 for an oxygen-containing fluidizing gas, which in the direction of arrow f into the chamber 43 is pushed or sucked in. This fluidizing gas flows over the nozzle tubes 37 and the nozzle bores 41 in the bed 29 and fluidized the existing there inert material, so that from the fluidizing bed Fluidized bed is formed.

Via local pressure tapping openings 47 in the shaft wall and 49 in the chamber the differential pressure between the chamber 25 and the gas chamber 43 measured and in entered a controller 51. There is a comparison with a predetermined setpoint for the pressure difference instead of. A control deviation is activated by pressing the Drive motor for a rotary valve 55 on the Output signal line 53 of controller 51 corrected. The Cell wheel lock 55 locks depending on the duration of the operation, which are matched to the desired pressure difference is a predetermined amount of inert material from the fluidized bed 29 via a discharge pipe 57, which penetrates the bottom 35 and the chamber 43 vertically.

The temperature in the fluidized bed 29 is determined by means of a Temperature sensor 59 detected and fed to a controller 61, which is a rule comparison with a given one Temperature setpoint in the order of 850 ° C and a control signal in the event of a control deviation via the control signal line 63 to a control valve 62 delivers. The control valve 62 is in a branch line 60 for oxygen-rich gas, e.g. Air, turned on, which in line 46 downstream from one to one Set flow valve 65 opens.

The two control loops with the controllers 51 and 61 are only shown in Fig. 1, but can also be other versions in the same or modified Form should be provided. For example, instead of a control valve in line 46 also a control the oxygen content in a pressure source for oxygen-containing Fluidizing gas may be provided.

The variant of Fig. 2, in the same parts not described again differs essentially in that the bottom 35 funnel-like to the central discharge pipe 57 is inclined. This means, that 29 different fluid bed heights in the fluidized bed rule: the fluidized bed height is greater in the middle as outside. So that the entire fluidized bed is even is fluidized, these different fluid bed heights accounted for by the fact that the nozzle bores 41 of the lower-lying nozzle pipes 37a larger are dimensioned higher than the nozzle bores 41 located nozzle pipes 37b, so that through the lower Nozzle tubes 37a flow larger amounts of gas than through the higher-lying nozzle tubes 37b.

Another difference in the embodiment according to FIG. 2 exists in that instead of a rotary valve 55 a Screw conveyor 56 for the lateral discharge of the Discharge pipe 57 ash to be extracted from the fluidized bed 29 is provided. The screw 56 can be placed in an ash container (not shown) then request the ashes fed back into the fluidized bed 29 via the screw 33 becomes.

3 is only different, that the bottom 35 funnel-like towards The shaft center is inclined upwards. So it favors that heavy or large parts, such as metal parts, that cannot be suspended due to their gravity and due to the movement in the Get the fluidizing bed into the discharge pipe 57. The ash is here over a surrounding the outer edge of the bottom 35 Ring channel 58 discharged through vertical pipes 59 below the chamber 43 with the central discharge pipe 57 communicates. In this case, the nozzles 37a are included larger nozzle bores on the outside and the nozzle tubes 37b arrange smaller nozzle bores on the inside. The highest central nozzle tube 37c expediently the smallest nozzle bores so that there is the least flows out oxygen-containing fluidizing gas.

In the variant according to FIG. 4, the chamber 25 tapers below the prism 9 in the shaft 1 downwards. The left shaft wall 1a lets you down to the floor Passage 67 free. The gas chamber 43 is through a partition 44 divided into two chamber halves 43a and 43b, both of which have their own gas inlets 45a and 45b are. A fluidized bed is formed here on the left and to the right of the wall la leaving the passage 67 Shaft in subspaces 29a, 29b, with the fluidized bed height in the fluidized bed part 29a in the shaft considerably is higher than the fluidized bed height in a closed Chamber part 69 containing the fluidized bed part 29b. Accordingly, it must pass through the nozzles 37d into the fluidized bed 29a introduced amount of fluidizing gas may be considerably larger than the amount of fluidizing gas supplied through the nozzles 37e. The nozzles 37e and 37d mentioned are correspondingly to dimension or the inlets 45a and 45b metered quantities of fluidizing gas supplied.

From the closed room 69 above the fluidized bed part 29b is obtained gas via a gas line 71 in the upper area of the shaft above the narrow points 17, 19 to promote degassing and gasification in this Shaft part returned. Alternatively, that can be done the gas discharged from the closed space 69 is also of another type Use can be supplied, for example a separate combustion process to obtain Useful heat.

5 is the fluidized bed 29 containing fluidizing chamber 75 from chamber 25 completely separated by a horizontal wall 73, so that a completely closed by the chamber 25 Fluidizing chamber 75 is formed. That in this fluidizing room 75 generated fluidized bed 29 is made with inert and material to be gasified as in the execution 1 to 3 via a screw conveyor 33 and an inlet 31, wherein the screw conveyor 33rd via a vertical pipe section 81 and a discharge screw 77 with drive motor 79 with from chamber 25 discharged ash and only partially gasified solids is fed.

In this case, too, as in the execution Fig. 4 from the fluidizing chamber 75 a gas line 71 back in the upper area of the shaft.

Otherwise, the design is the same as in the execution according to Fig. 1.

FIG. 7 shows a further variant of a gasification reactor according to the invention. The arrangement is with this Gasification reactor similar to that of Figure 4, and the same reference symbols are used for identical or similar components used.

Similar to Figure 4, the shaft wall la lowers to the bottom a side passage 67 free. Here, too, the gas chamber is separated by a partition 44 divided into two chamber halves 43a and 43b, both of which provided with their own gas inlets, not shown here are. Fluid bed parts 29a and 29b are formed in each case over the two chamber halves 43a and 43b, the Bottom of the fluidized bed part 29 inclined towards the partition 44 is. In these fluidized bed parts 29a, 29b there are nozzles 37m, 37n provided, as in the models according to 4 and 5 all end at the same level. The nozzles have a length of 37m.

In contrast to the embodiment according to FIG. 4, there is none Gas outlet 27, the gas directly from chamber 25 below the constrictions 17, 19, but one Gas outlet 27a from the closed chamber part 69 above the fluidized bed part 29b. So everything is generated gas withdrawn in cocurrent through outlet 27a. This means that the gas generated in shaft 1 via the fluidized bed part 29a, the passage 67 and the fluidized bed part 29b must flow before the outlet 27a in DC current is supplied. In contrast, it was generated gas in the embodiment of Figure 4 to a withdrawn substantial portion in countercurrent via the tube 27.

The partition 44 enables the pressures in FIG the chamber halves 43a, 43b independently of one another, in particular a variation in chamber half 43b. This allows different clearance speeds in the chamber parts 29a, 29b. Thereby and due to the slope of the floor in the chamber half 43a is the mass transfer for discharge into the chamber half 43b guaranteed.

In the variant according to FIG. 7, the generated mixes Gas with the gaseous and solid substances in the fluidized beds intensive. The dwell time is the Gases and dust particles in a zone of higher temperature extended. This leads to a more intense fabric and Heat exchange so that the gas quality of the through the outlet 27a withdrawn gas especially with regard to the energetic use in a downstream gas engine is improved (cracking of long-chain hydrocarbons, like tars).

The equilibrium reactions (Boudouard and / or Methane equilibrium) and thus the gas quality in relation the concentration of hydrogen or carbon monoxide can be controlled by temperature control of the fluidized bed improve.

FIG. 7 additionally shows one in the chamber 69 shortly before the gas outlet 27a arranged heat exchanger 90. This Heat exchanger enables energy extraction in Form of heat from the heat transfer medium flowing in the heat exchanger 90, like water or thermal oil. With that heat obtained can preheat gasification air, Pre-degassed fuel before it is introduced into the bed 7 or hot water.

In front of the heat exchanger 90 and the gas outlet 27a Hot gas filter 92 made of ceramic material in the chamber part 69a used, which ensure dust-free clean gas.

Claims (19)

1. Method of gasifying solids, especially residual matter, with which the solids are filled into a shaft (1), gasified at least partly with a controlled, substoichiometric supply of fresh air (18, 20), and the solid proportions not yet fully gasified and gases are fed through at least one bottleneck (17, 19) in the shaft into a chamber (25) in which the solid proportions are regasified and from which gases are withdrawn (27), a bed (29, 29a, 29b) being formed from which ash (57) is withdrawn,
   characterized in that into the bed (29, 29a, 29b) an inert, fluidizable material (31) as well as a fluidizing and reaction gas (45, 45a, 45b) in a quantity sufficient to create a fluidized bed is introduced.
2. Method as claimed in claim 1,
   characterized in that the fluidized bed is formed in the shaft (Fig. 1).
3. Method as claimed in claim 1,
   characterized in that the fluidized bed is formed below the shaft (Fig. 5) or beside the shaft (Fig. 7).
4. Method as claimed in any one of the preceding claims,
   characterized in that the height of the fluidized bed is controlled in response to a predetermined pressure difference above and below the fluidized bed.
5. Method as claimed in any one of the preceding claims,
   characterized in that as the fluidizing and reaction gas a mixture of air or oxygen and flue gas of the combustion process is used.
6. Method as claimed in any one of the preceding claims,
   characterized in that the temperature in the fluidized bed is kept at a predetermined value, preferably at about 850°C, by controlling the quantity of the fluidizing and reaction gas or the oxygen content thereof.
7. Method as claimed in any one of claims 3 to 6,
   characterized in that the fluidized bed is divided into a first fluidized bed portion (29a) at the bottom of the shaft (1) and a second fluidized bed portion (29b) beside the shaft, and the resulting gases are passed across the fluidized layers of both fluidized bed portions (29a, 29b) and withdrawn as a cocurrent from a gas outlet (71, 71a) above the second fluidized bed portion.
8. Gasification reactor with a shaft (1) to receive a fill of solids (7) for at least partial gasification thereof, with at least one support (9) for the fill of solids (7) defining at least one bottleneck (17, 19) for the passage of solids and gases, with fresh air conduits (18, 20) which open into the area above the bottleneck to introduce a controlled, substoichiometric quantity of fresh air, and with a chamber (25) disposed below the bottleneck with an outlet (27) for gases,
   characterized in that a gas chamber (43) separate from the chamber (25) is provided which includes a gas inlet (45) for a fluidizing and reaction gas, that the gas chamber (43) is closed at the top by a bottom (35) through which nozzles (37) pass, that a fluidizing space (29; 75) containing inert, fluidizable material is formed above the bottom (35), and that the fluidizing space includes an inlet (31) for the introduction of the fluidizable material and is in gas conductive communication with the chamber (25).
9. Gasification reactor as claimed in claim 8,
   characterized in that the fluidizing space (29) is formed in the bottom area of the chamber (25).
10. Gasification reactor as claimed in claim 8,
    characterized in that the fluidizing space (29a, 29b; 75) is separated from the chamber (25) by a wall (1a; 73) and includes a flue gas conduit (71) which may be connected to the shaft (1) above the bottleneck (17, 19).
11. Gasification reactor as claimed in claim 10,
    characterized in that the fluidizing space (75) is located below the shaft (1) and the horizontally extending wall (73) closes the shaft (1) at its lower end.
12. Gasification reactor as claimed in claim 10,
    characterized in that the fluidizing space is divided into two partial spaces (29a, 29b), one (29a) of which is disposed in the bottom area of the shaft (1) and the other one (29b) next to it, that the wall (1a) defines the lower end of a vertical, lateral limiting wall of the shaft (1) and leaves open a lateral passage (67) to establish a connection between the two partial spaces (29a, 29b), that the gas chamber (43) is divided by a partition wall (44) into two part chambers (43a, 43b) and that each part chamber has its own gas inlet (45a, 45b) for different admissions of fluidizing and reaction gas.
13. Gasification reactor as claimed in any one of claims 8 to 12,
    characterized in that a conveyor means (33) is provided to feed fluidizable material into the inlet (31) of the fluidizing space (29) above the bottom (35).
14. Gasification reactor as claimed in any one of claims 8 to 13,
    characterized in that a discharge pipe (57) for inert material extends through the bottom (35) and the gas chamber (43), a controllable discharge means (55) for inert material being arranged inside the discharge pipe.
15. Gasification reactor as claimed in claim 14,
    characterized in that the bottom (35) is inclined towards the discharge pipe (57).
16. Gasification reactor as claimed in claim 15,
    characterized in that those nozzles (37a) which extend through the lower parts of the bottom (35) have greater discharge flow cross sections (41) than the nozzles (37b) at the higher parts of the bottom (35).
17. Gasification reactor as claimed in any one of claims 13 to 16,
    characterized in that a level control means is provided to control the height (h) of the fluidized bed formed on the bottom (35), comprising pressure sensors (47, 49) to detect the pressure difference between the fluidizing space (29) and the gas chamber (43) and a controller (51) to control said pressure difference to a desired value by controlled discharge of fluidizable material through the discharge means (55).
18. Gasification reactor as claimed in any one of claims 8 to 17,
    characterized in that a temperature control means (61) is provided for the temperature in the fluidizing space (29), comprising a temperature sensor (59) to detect the temperature and control if to a desired temperature value by adjusting the quantity of fluidizing and reaction gas introduced through the gas inlet (45) or the oxygen content thereof.
19. Gasification reactor as claimed in any one of claims 12 to 18,
    characterized in that a chamber (69) disposed above the fluidized bed portion above the other partial space (29b) includes an outlet (27a) for gases so that the gas produced is withdrawn through the passage (67) and the fluidized beds above the two partial spaces (29a, 29b) in cocurrent through the outlet (27a).

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