DE2927240C2 - Method and device for gasifying lumpy fuels with pre-carbonization and cracking of the carbonization gases in the gas generator - Google Patents

Description

- that <£ e running thermal with partial combustion Cracking of the carbonization gases with intensive swirling of the gases above the carbonization coke in a free reaction space he follows,

- The reaction gases obtained in this way, the smoldering coke uniformly over its entire cross-section flow through distributed,

- the low-temperature coke is gasified from below in a reaction zone with the addition of steam, and

- the product gases of both processes are about mediocre be deducted from the smoldering coke.

2. The method according to Anspruri i, characterized in that that the carbonization gases generated are fed to the fuel gas generator separately from the carbonization coke will.

3. The method according to claim I _1, characterized in that the carbonization gases generated are supplied to the fuel gas generator together with the carbonization coke.

4. Device for performing the method according to one of the preceding claims, consisting from a shaft generator divided into several superimposed compartments, the at least is partially filled with the smoldering coke and in its upper area and in its bottom area Inlets for preheated air and connections for suction in a central section of the generated fuel gases, characterized in that

- That the shaft generator (2) in a known manner an indirectly heated smoldering drum (1) is connected upstream,

- That the upper part of the shaft generator (2) as a free vortex chamber (27) for the carbonization gases is trained,

- in which an ejector filled with the smoldering gases and preheated combustion air gate burner (24,26) opens.

5. Apparatus according to claim 4, characterized in that in the lower part of the vortex chamber (27) a gas-permeable partition (28,29) is arranged below which an entry device (30) for the coke separately discharged from the smoldering drum (1) is arranged.

6. Apparatus according to claim 4 or 5, characterized in that the trigger (36) for the fuel gases as an annular channel (36) on the outer circumference of the hose generator (2) trained isL

7. The device according to claim 4, characterized by a common drum discharge (132) for the carbonization gases and the carbonization coke in the swirl chamber (27).

The invention relates to a method for gasifying lump fuels, such as bituminous coal, Lignite, wood, straw and the like, at least below Approximate atmospheric pressure, at which the fuel is heated indirectly in a swell drum carbonized and then the hot carbonization gases in a shaft carburetor by feeding in preheated ones Air can be thermally cracked, the low-temperature coke formed by introducing an oxygen-containing gasification agent gasified, the resulting hot fuel gas is sucked through a column of charring, and the cracked smoldering gases together with the fuel gases produced during the smoldering coke gasification mixed suction «yerden.

The invention also relates to a device which is particularly suitable for carrying out this method.

In the past few decades there are already Variety of processes and plants for gasification, pyrolysis and / or high temperature distillation of Fuels of the most varied types have been developed, which are at least partially realized in practice became. This is consistently an initial fusion and / or coking the abandoned fuels in the absence of air by direct or indirect heating, by which the volatile constituents, if necessary with thermal cracking, are driven out of the solid fuels and deposited will. The coke formed during this process can, depending on the type and composition of the The fuels used are either withdrawn as a salable end product or by a more extensive one thermal treatment by supplying steam in preferably CH4-. Containing CO and Hi Fuel gases are gasified.

DE-PS 9 '2 468 describes a method for generating a fuel gas from bituminous fuels described, in which the fuels are degassed and in a first chamber of a conventional coke oven battery the distillation gases obtained via pipelines and a template into a second, identically designed Chamber are transferred, in which the glowing, already fully cooked distillation residues are of a previous degassing process. This chamber is externally through the chamber walls heat supplied through it. In order to control the composition of the generated fuel gases, finely atomized is used Fuel, e.g. B. oil or tar, along with the hot raw gas introduced into the second chamber. The finely atomized fuel in the connecting line forms Together with the hot raw gases, a warm aerosol is created in the void volume of the glowing coke is split. In addition to spraying liquid fuel, water or steam can also be added to the raw gases be added in order to carry out the water-gas reaction in the glowing coke of the second chamber.

■ p. S,

Ren. According to this process, a fuel gas enriched in the calorific value can be generated, the coke in However, the second chamber takes part in the reactions only in extremely small quantities, so that gasification this coke does not occur or only occurs to a practically insignificant extent

From DE-PS 7 42 272 a method for generating a low-hydrocarbon gas from bituminous lump fuels known, in which the lumpy Fuels slowly sink down in the middle part of a smoldering and degassing shaft and are heated by rising hot gases, which arise in a single lower gasification zone. The carbonization gases are released via a water gas and carbonization gas line connected to the upper end of the shaft guided into a lower ring channel from which they are angularly offset from one another by a large number of arranged mixers flow together with the oxygen carrier into an annulus free from the low-temperature coke. The carbonization gases are to be cracked in this annulus and the adjacent ones are to take place at the same time Smoldering coke layers are warmed up so much that degassing takes place the lumpy fuel during their sinking movement in the shaft has the disadvantage that over the entire Cross-sectional area no approximately constant temperatures can be maintained, which in particular If the fuel has a high water content, this leads to uneven smoldering processes

In AT-PS 1 70 621 is a method and a device for the simultaneous generation of tar-containing and tar-free gas described, in which the tar Old, steam-rich raw gas is added to preheated secondary air and this mixture from above directed through a nozzle with lateral outlet slots onto the degassed fuel in the gasification chamber will. The gasification chamber is also fed into the gasification air preheated through a rotating grate from below and the tar-free product gas is withdrawn from it. All thermal processes, i. H. the smoldering, Cracking and degassing take place in a single reactor. without effectively influencing the individual processes or can be controlled.

From DE-AS 24 32 504 a method and a system for producing fuel gases from lumpy, unvorbehaidelt domestic and industrial waste and the like. Known in which the sometimes high moisture content waste materials in a first process stage un ter constant circulation by indirect Heating in a smoldering drum bc ^; Temperatures between 300 and 600 ° C become carbonized. The carbonization gases obtained expectant-n in a naohgeschalteten reactor introduced from above and cracked under lateral feeding preheated air in the accumulated coke, from which the non-combustible components have been previously sorted out, at temperatures of 1000-1200 ⁰ C in the downward pull. For this purpose, the carbonization gases flow through a reaction zone in the reactor, which is formed from glowing-hot carbonized coke. Complete gasification of the smoldering coke formed in the smoldering drum during the smoldering process is, among other things. not intended because of the relatively high proportion of pollutants in the solid smoldering residues.

DE-PS 6 46 277 discloses a gas generator with a downward train and double air supply known, in which a fuel gas is generated from bituminous fuels that tend to form slag.

Part of the air required for degassing and gasification is introduced preheated through a central tube that protrudes from above through the upper fuel layers Smoldering and water vapors are sucked into this air tube and get mixed with the air into the fire zone, which is also supplied with air from below, in the middle, whereby the Smoldering gases and the air, melting of the slag in the inner fire zone should be avoided. The product gas is withdrawn from the gasification chamber at the bottom, is used for indirect heating of the fuel and the air and then exits the gas generator.

Finally, DE-PS 4 79 032 discloses a method and a device for generating stable gases to be taken from preferably inferior fuels, in which the gas generation in three procedural terms separate processes, namely smoldering, cracking by coke gasification in the top fire and gasification of the residual coke in the lower fire. The cracked carbonization gases and those from coke gasification Coming fuel gases are drawn off together through a ring line in the middle of the coke bed. Is disadvantageous however, also with this procedural lead. the charring of the fuels entered from above in a shaft in which the smoldering processes take place evenly across the entire shaft cross-section cannot be guaranteed, and also the cracking of the carbonization gases in the coke bed and the absence of Regulation and control options that go beyond the control in the hot air supply.

The object of the invention is to provide a method and a device of the specified type in the manner to train that a uniform exhaustion of the fuels and on the other hand a uniform and complete thermal cleavage of the obtained

Carbonization gases without overheating is achieved with complete gasification of the fuel.

According to the invention, this object is achieved in that the thermal Cracking of the carbonization gases with intensive turbulence of the gases above the carbonization coke in a free one Reaction chamber takes place, the reaction gases obtained in this way, the low-temperature coke over its entire cross-section Evenly distributed, the low-temperature coke flows through from below in a reaction zone with the addition of steam is gasified, and the product gases of both processes are drawn off approximately in the middle of the charcoal coke column.

By swirling the carbonization gases with the preheated air in the free space above the coke bed an almost uniform temperature is achieved in this reaction chamber, which is controlled by appropriate control the amount of air in a simple manner to a level sufficient for the complete cracking of the carbonization gases Value can be set and held. This ensures that the thermally split Carbonization gases with approximately the same temperatures are distributed evenly over the entire shaft cross-section in the The hot reaction zone which forms in the coke bed can be reached without overheating zones in the low-temperature coke develop.

The device which is particularly suitable for carrying out the method contains one in several superposed Compartments subdivided shaft reactor which is at least partially filled with the smoldering coke and in its upper area as well as in its bottom area feeds for preheated air as well as in his middle section has connections for sucking off the generated fuel gases. This is according to the invention A shaft reactor in a manner known per se

indirectly heated smoldering drum upstream and its upper part is as a free vortex chamber for the Carbonization gases formed, in which a charged with the carbonization gases and preheated combustion air Ejector burner opens.

Expedient further developments and refinements of the invention are the subject matter of subclaims.

The following are exemplary embodiments of the invention described in detail with reference to the drawing. 6s shows

F i g. 1 the block diagram of a first embodiment,

2 shows the fuel gas generator of the system according to FIG. 1 in an enlarged schematic representation,

F i g. 3 the block diagram of another embodiment with common charging of the fuel gas generator with carbonization gas and carbonization coke.

The device shown in Fig. 1 contains a smoldering drum 1 as a main unit, a shaft generator 2 and a gas engine 3.

The lumpy bituminous fuels are introduced into the entry end of the Schvveltrommel 1 via a funnel 4 with locks 5, 6 arranged in an entry shaft 7 and a horizontal conveyor 8. The smoldering drum 1 consists of a drum 10, in which hollow, essentially longitudinally oriented internals 11 are arranged in the form of longitudinal ribs or blades. This drum 10 is surrounded by a jacket 12 which is connected to the exhaust system 14 of the gas engine 3 via a line 13. In this way, the smoldering drum is heated indirectly by the exhaust gases from the gas engine 3, ^{which have a temperature of approx. 600 0 C.} Start the fuel inside the drum. In normal operation, however, the heat available in the exhaust gases of the gas engine 3 is sufficient for complete carbonization of fuels, even with a high ash and water content. To intensify the heat transfer between the hot exhaust gases and the smoldering material, the hollow internals 11 are flowed through by the hot exhaust gases, which on the one hand increases the heat-transferring surfaces and on the other hand improves the heat transfer to the task or smoldering material due to the conveying effect of these internals. If these internals 11 are designed accordingly, their interiors can be enlarged so that they themselves form the jacket 12. After flowing through the internals 11 or the drum shell 12, the exhaust gases are discharged into the atmosphere via a line 16 with a metering valve 17. The line 16 is through a branch line 18, a fan 19 and a metering valve 20 with the burner 15 or the inlet-side distribution chamber 21 connected in the drum shell 12 in order to control the temperature of the heating gases by admixing predetermined, already cooled gas quantities. The smoldering drum 1 is adjustable in inclination in the usual way on support and drive rollers - not shown

The carbonization gas produced in the carbonization drum 1 is fed at temperatures of 400 to 500 ⁰ C at the discharge end of the drum via pipes 22 to a burner 23 which in the upper part of the shaft generator 2 opens UnmitteFbar upstream of an ejector part 24 a supply conduit ends 25 for the combustion air, which is intensively mixed in the ejector part 24 and the adjoining diffuser 26 of the burner 23 with the carbonization gases for partial combustion of the carbonization gases.

In its upper part, the shaft generator 2 has a chamber 27 which is free of internals and in which there is an intensive swirling of the partially burned carbonization gases flowing in through the burner 23. The thermal cracking of the carbonization gases heated ^{to approx. 1000 to 1200 °} C. by the substoichiometric partial combustion takes place in this chamber

ίο This chamber 27 is delimited at the bottom by a partition 28, which consists of a ceramic plate from about 100 to 200 mm thick, in which a plurality of holes 29 are provided in a suitable size are. The flow resistance of this plate 28 or the holes 29 is chosen so that in the chamber 27 there is a slight overpressure, one over the The entire cross section of the shaft-shaped fuel gas reactor ensures a uniform flow through the plate 28.

At a predetermined distance below the gas-permeable partition 28 is at least one entry conveyor 30 is provided, which is a hydraulically or pneumatically operated piston valve as the entry member 31 has this infeed conveyor 30 is the smoldering coke from the discharge end of the smoldering drum 1 fed via a chute 32 and a pressure-tight metering device 33 to the feed conveyor 30 feeds the shaft generator 2 via a lateral, sealed entry opening 34 with the in the Smoldering drum 1 produced smoldering coke. The charging of the shaft generator takes place in such a way that a sufficient height of the coke bed 35 is available

At a predetermined distance below the infeed conveyor, a vent for the combustion gases designed as an annular channel 36 is provided, which consists of a plurality of radial openings 36a in the generaior wall
The generator base is formed by a discharge conveyor 37 for the ash and slag of the low-temperature coke, which is driven by a motor 38 via a gear 39. Below this discharge conveyor 37, which is designed as a rotating grate, a discharge chute 41 is provided, which is sealed by a piston slide 40 and through which the ash or slag loosened and comminuted by means of the discharge conveyor 37 is discharged. Air and steam lines 50, 56 open into the interior of this discharge chute 41 via an annular channel 42.

From the Bren / Jas fume cupboard designed as an annular channel 36 A hot gas line 43 leads to an air preheater 44 and to evaporators 45, 46. The air preheater 44 is via a warm air line 47 with an air line leading to the pipe 25 via a metering valve 49 48 and connected to the annular channel 42 via an air line 50 and a further metering valve 51. In the Evaporators 45 and 46 are evaporated soft amounts of water supplied by means of metering pumps 53,54 once via a steam line 55 into the hot air line 48 downstream of the valve 49 and the other via A further steam line 56 can be fed into the hot air line 50 downstream of the metering valve 51.

The combustion gases flow from the heat exchangers 44 to 46 via a gas line 60 into one only schematically illustrated scrubber 6i, in soft pollutants and other by-products, possibly in several Levels are deposited. The cleaned fuel gas is drawn to the gas engine 3 via a line 62.

leads whose Abtriebsweüe is coupled to a power generator 63

The following is the operation of that described above Device and in particular the shaft generator (with reference to FIGS. 1 and 2) detailed described.

The bituminous fuels, such as sulphurous and ash-rich coal, lignite, peat, wood and wood waste as well as straw and other organic components, are fed in via an endless conveyor (not shown) and enter the entry shaft 7 through the funnel 4 by alternately actuating the piston slides 5, 6 which they are introduced into the interior of the carbonization drum 1 by means of the screw conveyor 8 After drying in in Fig. 1 left is part of the carbonization drum is at about 200 ⁰ C, the degassing of the fuel, which up to temperatures of about 500 ⁰ C. is continued continuously at the right discharge end of the drum. Ute carbonization gases are sucked off by the ejector effect of the burner 23 via the lines 22 at temperatures of approx. 400 to 500 ° C. At the same time, the coke is introduced into the shaft generator 2 below the partition 28 via the discharge chute 32, the metering wheel 33 and the feed conveyor 30.

The carbonization gases are partially burned by adding dosed amounts of air in the burner 23 and flow with comparatively high kinetic energy into the empty chamber 27, in which intensive turbulence of the gases 1 takes place (zone I). These eddy currents cause a temperature of approx. 1000 ° C to prevail in the entire chamber, at which the thermal cracking of the carbonization gases takes place with a high degree of efficiency. The maintenance of the temperature is achieved by introducing appropriate amounts of air and thus by increasing the intensity of the carbonization gas emissions is heated to 1000 ° C. The elements of elemental carbon (soot) formed during the cracking process and the substoichiometric combustion of the carbonization gases are deposited on the surfaces of the carbonization grains and react with the combustion products and with the water vapor under carbon monoxide, hydrogen and carbon monoxide possibly methane formation (zone II). These processes are strongly endothermic, so that the gases flowing in from the partial combustion and cracking zone I through the partition 28 into the water gas reaction zone II in the coke layer 35 from initially 900 to 1000 ° C to a discharge temperature cooled from approx. 500 ° C. through the openings 36a in the refractory brickwork Walls of the shaft generator 2 and the annular channel 36 are discharged (discharge zone III).

Via the line 50, the annular channel 42 and the openings 42a in the reactor wall into the space 41 Gasification air introduced under the conveyor flows through the spaces between the grate bars 37 and there is a partial combustion of the low-temperature coke in one at zone V directly above the Roeo stes 37 Temperature range from IOCO to 1200 ° C. The intensity of this partial combustion is determined by adjusting the air supply controlled by means of the metering valve 51 the gases formed by the partial combustion of the smoldering coke flow through the reduction zone IV of the coke bed and through the discharge openings 36a, the annular channel 36 and the fuel gas line 43 from the shaft generator deducted. Due to the steam added to the combustion air, this takes place The coke filling in reaction zone IV also flows through strongly endothermic reactions, with an increase in calorific value and simultaneous temperature reduction - corresponding to the reactions in Zone II -.

The device shown in FIG. 3 corresponds in its essential components and functional features to those according to FIG. 1. The components that correspond to one another are identified by reference numerals extended by 100. This device is particularly suitable for feed materials in which the carbonized coke accumulating in the carbonization drum is sufficiently granular on the one hand to be able to be introduced into the combustion gas generator together with the carbonization gases via the burner 123 , and in which it forms a coke bed of sufficient gas permeability. On the other hand, the coke should be co-processed by the combustion gases in space 127 in order to enable a largely uniform deposit over the entire cross section of the fuel gas generator.

With regard to the investment costs, this embodiment offers the advantage that the separate feed conveyor 30 for the low-temperature coke and the gas-tight metering wheel sluice 33 can be omitted. In order to ensure that the coke bed 135 in the reactor 2 is continuously supplemented, the perforated partition 28 according to FIG. 1 is also missing in this embodiment. 1. It follows that the variant according to FIG. 3 is constructed in a technically simpler manner, however, that the control of the process sequence offers fewer possibilities for intervention, since all of the carbonized coke discharged from the carbonization drum 110 reaches the fuel gas reactor directly. The other units (such as heat exchangers, scrubbers, gas engines, etc.) of this system correspond to those according to FIG. 1.

The preheating of the combustion air and / or the Steam generation for the water gas reaction can in the third process stage by further utilization of the Waste heat from the exhaust gases of the gas engine take place.

For special purposes, especially for the use of fuels with a high ash content, where the distinctive ingredients tend to cake and sinter together is another Process and plant variant suitable in which the low-temperature coke in the generator shaft is wholly or partially is placed in the state of a calm fluidized bed. This is done in the air chamber on the bottom a sufficiently high overpressure is generated, which leads to gas flows evenly distributed over the floor cross-section leads into the charcoal coke filling. Should the amount of gas necessary to generate the fluidized bed the amount of air required for partial combustion of the coke can be exceeded by this combustion air either a corresponding partial amount of generated fuel gas and / or a corresponding partial amount be mixed in with exhaust gases.

For this purpose 3 sheets of drawings

Claims (1)

Patent claims: 1. Process for gasifying lump fuels, such as bituminous coal, lignite, wood, straw and the like, at least approximately Atmospheric pressure at which the fuels are carbonized by indirect heating in a smoldering drum and then the hot smoldering gases in a shaft carburetor by feeding in preheated ones Air can be thermally cracked, the smoldering coke formed by introducing an oxygen-containing Gasification agent gasified, the hot fuel gas formed sucked through a column of charring and the cracked smoldering gases together with those from smoldering coke gasification resulting fuel gases are extracted mixed, characterized in that