EP2808377B1 - Installation and process facility for gasifying lumpy fuels - Google Patents

Description

The invention relates to a system for gasifying lumpy fuels according to the preamble of claim 1.

In known systems for gasifying particulate fuels with a pyrolysis reactor and a gas engine useful heat and useful energy in the sense of a cogeneration can be provided in a simple manner.

From the WO 2011/110138 A1 a pyrolysis reactor is known, wherein the pyrolysis products are fed to a gasifier. The product gas of the carburetor is treated and fed to a two-stroke engine. The exhaust gases of the two-stroke engine are used to heat a first, cooler stage of the pyrolysis reactor. Further, part of the product gas of the gasifier is used to directly heat a second, hotter stage of the pyrolysis reactor.

From the DE 43 42 165 C1 is known a plant for the utilization of fuels, wherein the fuels are dried, smoldered, gasified and then supplied as gas to a gas turbine.

From the WO 2000/71934 A1 is a method for the thermal disposal of waste in fossil-fired power plants known.

The object of the invention is to provide a system for gasifying lumpy fuels of the type mentioned, with which a high efficiency can be achieved.

This is achieved by the features of claim 1 according to the invention.

This results in the advantage that a high degree of efficiency can be achieved because the external heat input at high temperature during the pyrolysis can be done efficiently and a partial combustion of the fuel can be minimized. Gasification plants also often have a high carbon monoxide content in the product gas. The flushing losses of the gas engine can lead to an increased carbon monoxide concentration in the exhaust gas of the gas engine. By the afterburning combustion chamber, a largely complete combustion of the exhaust gas pollutant carbon monoxide can be ensured become.

Furthermore, the invention relates to a method for gasifying particulate fuels according to claim 11.

The object of the invention is further to provide a method for gasifying particulate fuels of the type mentioned, with which a high efficiency can be achieved.

This is achieved by the features of claim 11 according to the invention.

This results in the advantages mentioned above.

The subclaims relate to further advantageous embodiments of the invention.

It is hereby expressly referred to the wording of the claims, whereby the claims at this point by reference into the description are inserted and considered to be reproduced verbatim.

• Fig. 1 bis 3 zeigen schematische Darstellungen dreier bevorzugter Ausführungsformen einer Anlage zum Vergasen von stückigen Brennstoffen.

The invention will be described in more detail with reference to the accompanying drawings, in which only preferred embodiments are shown by way of example. Showing:

• Fig. 1 to 3 show schematic representations of three preferred embodiments of a plant for gasifying lumpy fuels.

The Fig. 1 to 3 show different embodiments of a plant 1 for gasification of particulate fuels with a pyrolysis reactor 2 and a gas engine 6. The particulate fuels may in particular be biogenic fuels, in particular wood or halmgutartige substances. The pyrolysis reactor 2 is used for pyrolysis of the lumpy fuel.

In the schematic representations in the Fig. 1 to 3 the flow of chunky fuel and its products is represented by solid arrows. A dashed arrow represents an air supply in most cases. A discharge of useful heat is represented by a single-line arrow. A discharge or supply of steam is represented by a hook-shaped arrow. A double-crossed arrow represents a release of electrical energy.

The pyrolysis reactor 2 may be particularly preferably designed as a double-shell pyrolysis reactor 21, which has a pyrolysis chamber 24 and an outer chamber 28. The pyrolysis chamber 24 may in particular be tubular and have at one end a fuel supply 22, which is provided for equipping the pyrolysis chamber 24 with the lumpy fuel. Furthermore, it can be provided that in the pyrolysis 24, a screw conveyor for further transport of the lumpy fuel is arranged. The outer chamber 28 is preferably arranged at least partially around the pyrolysis chamber 24. The outer chamber 28 serves to heat the pyrolysis chamber 24, in particular by receiving a hot gas. Here, the heating of the lumpy fuel in the pyrolysis 24 can be done indirectly.

It is provided that an exhaust gas outlet 65 of the gas engine 6 is connected to an input 71 of an afterburner combustion chamber 7. In the afterburning combustion chamber 7, the temperature of the exhaust gas of the gas engine 6 is increased. Incomplete burned portions of the exhaust gas are completely burned. The afterburning combustion chamber 7 comprises a burner, particularly preferably a gas burner, the heat being supplied into the afterburning combustion chamber 7 through the burner. Depending on the type of fuel used, the burner may be designed in the afterburner combustion chamber 7 as a gas burner, liquid burner or solid fuel burner. An exhaust gas outlet 75 of the afterburner combustion chamber 7 is connected to at least one heating gas inlet 23 of the pyrolysis reactor 2. In this case, the heat of the exhaust gas of the post-combustion combustion chamber 7 is used for the pyrolysis in the pyrolysis reactor 2. In this case, the pyrolysis process can be improved by the increased temperature of the heating gas from the afterburning combustion chamber 7 compared to the temperature of the exhaust gas from the gas engine 6. Furthermore, thereby the throughput of the lumpy fuel through the pyrolysis reactor 2 can be increased. Furthermore, a method for gasifying particulate fuels is provided, wherein the particulate fuels in the pyrolysis reactor 2 subjected to pyrolysis and then gasified to a product gas, wherein the product gas formed by the gasification gas is supplied to the gas engine 6, wherein exhaust gases of the gas engine 6 in the Afterburning combustion chamber 7 are guided and heated there by means of a burner, and wherein exhaust gases of the post-combustion chamber 7 are fed into the pyrolysis reactor 2. The product gas may be a combustible gas, the essential combustible constituents of which are carbon monoxide and hydrogen. The carbon monoxide content in the product gas may be in particular between 15% and 40%.

The gas engine 6 may be in particular for the production of electric power and useful heat. In this case, the gas engine 6 can in particular have an air inlet 62, via which air or another oxygen-containing gas in the gas engine 6 can burn together with the product gas. For the sake of brevity, each oxygen-containing gas is referred to as air in sequence.

In this case, it can be provided in particular that the exhaust gases of the gas engine 6 are heated in the afterburner combustion chamber 7 to a temperature greater than 800 ° C. Here, the heating gas for the pyrolysis reactor 2 have an initial temperature which is greater than 800 ° C, in particular between 800 ° C and 950 ° C. Here, the exhaust gases of the gas engine 6 usually have a temperature of about 600 ° C. Furthermore, it can be provided that the exhaust gases of the gas engine 6 are heated by the afterburner combustion chamber 7 by at least 200 ° C.

In the pyrolysis of the lumpy fuel, a pyrolysis gas, a pyrolysis coke and a pyrolysis oil is preferably produced from the lumpy fuel. Pyrolysis here refers to the thermal decomposition of chemical compounds under oxygen deficiency. The pyrolysis reactor 2 may in particular be free of an air supply. The ratio of these pyrolysis products usually depends on the nature of the lumpy fuel and the process parameters of the pyrolysis.

In particular, it may be provided that a pyrolysis gas outlet 25 of the pyrolysis reactor 2 is connected to an inlet 31 of an oxidation chamber 3 and a coke outlet 26 of the pyrolysis reactor 2 is connected to an inlet 41 of a reduction furnace 4. In this case, a stepped gasification of the solid fuels is provided, whereby a separate optimization of the individual process steps can take place.

In this case, it can be provided that the pyrolysis gas from the pyrolysis reactor 2 is partially oxidized in an oxidation chamber 3, and that the product gas is obtained from a pyrolysis coke of the pyrolysis reactor 2 in the reduction furnace 4.

The oxidation chamber 3 may have an air inlet 32 and a steam inlet 33 through which air and water vapor can enter the oxidation chamber 3 and react there with the pyrolysis gas. In particular, the oxidation chamber 3 may have a temperature of about 1050 ° C. Due to the partial oxidation of the pyrolysis gas in the oxidation chamber 3, an oxidation product of the partial oxidation can be obtained.

Furthermore, it can be provided that the oxidation chamber 3 has an oxidation product output 35, and that the oxidation product output 35 of the oxidation chamber 3 is connected to the inlet 41 of the reduction furnace 4. In this case, the oxidation product of the oxidation chamber 3 can be further processed in the reduction furnace 4.

The reduction furnace 4 may have an air inlet 42 and a steam inlet 43 through which air and water vapor can enter the reduction furnace 4 and react with the pyrolysis coke. In the reduction in the reduction furnace 4, the product gas is recovered from the pyrolysis coke and the oxidation products. During the reduction, an ash also falls, which can be eliminated from the reduction furnace 4 via an ash outlet 46.

Particularly preferably, it may be provided that the reduction furnace 4 has a reduction zone and an afterburner zone arranged below the reduction zone (viewed in the operating position), and that a gas collection space is arranged between the reduction zone and the post-combustion zone. The reduction of the pyrolysis coke is carried out in the reduction zone, the pyrolysis coke here being present as a bed. The post-combustion zone serves to post-combust the ash from the reduction zone and to reduce the carbon content in the ash to further increase the cold gas efficiency. The gas collection chamber 4 serves to receive and pass on the product gas obtained in the reduction zone and in the post-combustion zone, whereby the reduction zone and the post-combustion zone can be separated in terms of process, since the product gas of the reduction zone is no longer guided through the post-combustion zone and vice versa. By means of this process-technological separation, the reduction zone and the post-combustion zone can be optimized independently of each other for the respective task. In this case, for example, the temperature, the residence time and the degree of turbulence of the gas stream can be adapted to the procedural requirements of reduction and post-combustion.

It can preferably be provided that the reduction zone is surrounded at least in regions by an annular gas deflection chamber, and that the gas deflection chamber connects the gas collection chamber 4 with a gas outlet opening.

In the gas deflection chamber, the product gas leaving the reduction zone is deflected, in particular upwards, whereby solid particles can settle out of the product gas stream.

Particularly preferably, provision can be made for the post-combustion zone to comprise a plurality of stacked ashtrays with a circulating and stripping device. As a result, the ash can be placed on a large area for afterburning, whereby a constant circulation can take place, wherein the surface of the ashes available for the afterburning is always renewed. Furthermore, in this case the ash can be post-combusted in stages, wherein, for example, the oxygen content of the gas fed in the post-combustion zone can be adapted to the degree of burning of the ash.

Particularly preferably, it can be provided that a bottom of the reduction zone is formed by a reduction grid and that the reduction grid is operatively connected to a central displacement device. In this case, the displacement device can be fastened in particular to the reduction grid. The reduction grid in this case preferably forms an impenetrable for the reduction material bearing surface. The displacer device is particularly preferably designed such that the solid reducing material is kept away from the center of the bottom of the reduction zone, since this region forms a dead zone for the transport of solids and for the gas-solid reactions, ie a reduction dead zone.

Particularly preferably, it can be provided that the displacement device has a first section widening from the reduction grid and a second section mounted on the first section, and that the second section is designed as a displacement cone. In this case, a cross-section of the reduction zone is first narrowed by the second section in the direction in which the particulate material to be reduced passes through into the reduction zone, and then subsequently expanded again. In this way, a loose bed can be formed in the region of the reduction zone adjoining the first section.

Furthermore, it can be provided that the displacer device has stirring arms.

By the stirring arms, a steady movement and a mechanical crushing of the reduction material can be achieved.

Particularly preferably, it can be provided that the stirring arms are arranged in a region of the largest diameter of the displacer device. In particular, the area of the largest diameter of the displacer device may be the transition from the first section to the second section. In this case, the probability of the formation of a blocking or bridge formation can be effectively counteracted, since this is greatest in the area of the cross-sectional narrowing.

Furthermore, it can preferably be provided that the displacer device has gas passage openings in the region adjacent to the reduction grid. As a result, the reduction dead zone can be further reduced since the withdrawal of the product gas can take place via the displacer device arranged in the middle.

Particularly preferably, it is provided that a product gas outlet 45 of the reduction furnace 4 is connected to an inlet 61 of the gas engine 6. The product gas generated with the reduction furnace 4 is at least partially supplied to the gas engine 6 and utilized by this. This recovery can be in the sense of a combined heat and power in the provision of electricity and useful heat by the combustion of the product gas.

As in the preferred embodiments in FIGS Fig. 1 to 3 can be provided in particular that between the product gas outlet 45 of the reduction furnace 4 and the input 61 of the gas engine 6, a gas treatment device 5 may be interposed. By the gas processing device 5 can be ensured that the operation of the gas engine 6 disturbing components of the product gas generated by the reduction furnace 4 are removed. Here, the product gas can be purified from the reduction furnace 4 and cooled.

It can preferably be provided that the gas treatment device 5 has a cyclone 51, which cyclone 51 is a coarse dedusting of the product gas performs.

Furthermore, it can be provided that the gas treatment device 5 has a waste heat boiler 52, wherein the waste heat boiler 52 from the waste heat of the product gas useful heat and / or steam wins. The product gas can be cooled down to approximately 100 ° C.

Furthermore, it may be provided that the gas conditioning device 5 has a dedusting device 53, wherein the dedusting device 53 may in particular comprise a fabric filter, with which a fine dedusting of the product gas is carried out.

It can preferably be provided that the gas conditioning device 5 has a gas conditioning device 54. In the gas conditioning device 54 in this case water can be injected, wherein the product gas is dried by condensing and further cooled. In this case, the product gas can be largely freed from ammonia and other pollutants in particular. Particularly preferably, it can be provided that between the product gas outlet 45 of the reduction furnace 4 and the inlet 61 of the gas engine 6, a bypass line 91 is guided to the input 71 of the afterburner combustion chamber 7. The bypass line 91 may in this case open directly into the burner of the afterburning combustion chamber 7, wherein the bypass line 91 may be formed as a fuel gas supply for the burner of the afterburning combustion chamber 7. The burner of the afterburning combustion chamber 7 can be operated with the product gas generated by the reduction furnace 4, which can be largely dispensed with further energy sources in addition to the pyrolysis reactor 2 supplied solid fuels. Preferably, the bypass line 91 is branched off after the gas treatment device 5, whereby the purified product gas is also supplied to the afterburner combustion chamber 7, where it is burned in the burner.

In this case, in particular, the product gas can be used as fuel gas for the burner of the afterburning combustion chamber 7.

In this case, in the afterburning combustion chamber 7 optionally a Maintain process condition, which ensures the combustion of incompletely burned portions of the exhaust gas of the gas engine 6.

The afterburning combustion chamber 7 may have an air inlet 72 through which combustion air can pass into the afterburning combustion chamber 7. In particular, the air inlet 72 can open directly in the burner of the afterburning combustion chamber 7.

Furthermore, it can be provided that optionally the product gas or a foreign gas is burned in the afterburning combustion chamber 7. In this case, in particular in the burner, a direct combustion of air with product gas or foreign gas can take place. The foreign gas may be another combustible gas which has a higher calorific value than the product gas. The fuel gas may in particular contain natural gas or liquefied gas. Here, the afterburner combustion chamber 7 may have an additional foreign gas input, wherein optionally can be switched between a feed of the product gas, the foreign gas or a mixture of the two. In this case, the foreign gas can be used in particular in a starting phase of the method, wherein in a regulating operation mainly product gas is used for the combustion in the afterburning combustion chamber 7.

In particular, it may be provided that the burner of the afterburning combustion chamber 7 is open to the afterburning combustion chamber 7. Here, the hot exhaust gases of the burner can mix with the exhaust gases from the gas engine 6 and leave them together through the exhaust gas outlet of the afterburner combustion chamber 7.

At least one heating gas outlet 27 of the pyrolysis reactor 2 may be connected to a first inlet 81 of a heat exchanger 8. With the heat exchanger 8, at least part of the waste heat remaining after the pyrolysis reactor 2 in the heating gas can be used.

The exhaust gas outlet 75 of the afterburner combustion chamber 7 can be connected directly to the first input 81 of the heat exchanger 8 via an exhaust gas bypass line 92. Through the exhaust gas bypass line 92, the pyrolysis reactor the second supplied amount of heat to be controlled, with excess heat is passed over the exhaust gas bypass line 92 to the pyrolysis reactor 2. In this case, a particularly simple control can be ensured with a short reaction time of the amount of heat provided.

As in the preferred embodiment in Fig. 3 in particular, between the exhaust gas outlet 65 of the gas engine 6 and the inlet 71 of the afterburner combustion chamber 7, an exhaust gas purification device 69 can be interposed. The exhaust gas purification device 69 may be designed in particular for minimizing nitrogen oxides.

In this case, provision can be made for nitrogen oxides to be removed from the exhaust gas of the gas engine 6 in the exhaust gas purification system 69 before the afterburner combustion chamber 7.

As low has been found when the pyrolysis reactor 2 is designed as a double-shell pyrolysis reactor 21 with an outer chamber 28. In this case, the at least one heating gas inlet 23 of the pyrolysis reactor 2 may be connected to the outer chamber 28 of the double-shell pyrolysis reactor 21.

A particularly high degree of efficiency can be achieved if the outer chamber 28, seen in the longitudinal direction of the double-shell pyrolysis reactor 21, has at least two heating chambers 29 arranged one behind the other and acted upon in parallel. Such a pyrolysis reactor is in Fig. 2 and Fig. 3 shown.

Due to the split-executed outer chamber 28, the flow of the heating gas can be shared and for different zones of the pyrolysis 24 different temperatures can be achieved. In this case, further, the heat transfer in the pyrolysis reactor can be increased while reducing the Heizgasstromdruckverlustes.

Claims (15)

1. An installation (1) for gasifying lumpy fuels with a pyrolysis reactor (2) and a gas motor (6), wherein an exhaust gas outlet (65) of the gas motor (6) is connected to an input (71) of an afterburning combustion chamber (7), wherein an exhaust gas outlet (75) of the afterburning combustion chamber (7) is connected to at least one heating gas inlet (23) of the pyrolysis reactor (2), characterized in that the afterburning combustion chamber (7) comprises a burner, and heat supply to the afterburning combustion chamber (7) occurs by the burner.
2. An installation according to claim 1, characterized in that a pyrolysis gas outlet (25) of the pyrolysis reactor (2) is connected to an inlet (31) of an oxidation chamber (3), and a coke outlet (26) of the pyrolysis reactor (2) is connected to an inlet (41) of a reduction furnace (4).
3. An installation according to claim 2, characterized in that a product gas outlet (45) of the reduction furnace (4) is connected to an inlet (61) of the gas motor (6).
4. An installation according to claim 3, characterized in that a gas treatment device (5) is interposed between the product gas outlet (45) of the reduction furnace (4) and the inlet (61) of the gas motor (6).
5. An installation according to claim 3 or 4, characterized in that a bypass line (91) is guided to the inlet (71) of the afterburning combustion chamber (7) between the product gas outlet (45) of the reduction furnace (4) and the input (61) of the gas motor (6).
6. An installation according to one of the claims 1 to 5, characterized in that at least one heating gas outlet (27) of the pyrolysis reactor (2) is connected to a first inlet (81) of a heat exchanger (8).
7. An installation according to claim 6, characterized in that the exhaust gas outlet (75) of the afterburning combustion chamber (7) is directly connected via an exhaust gas bypass line (92) to the first inlet (81) of the heat exchanger (8).
8. An installation according to one of the claims 1 to 7, characterized in that an exhaust gas purifying device (69) is interposed between the exhaust gas outlet (65) of the gas motor (6) and the inlet (71) of the afterburning combustion chamber (7).
9. An installation according to one of the claims 1 to 8, characterized in that the pyrolysis reactor (2) is formed as a double-jacket pyrolysis reactor (21) with an outer chamber (28), and the at least one heating gas inlet (23) of the pyrolysis reactor (2) is connected to the outer chamber (28) of the double-jacket pyrolysis reactor (21).
10. An installation according to claim 9, characterized in that the outer chamber (28), as seen in the longitudinal direction of the double-jacket pyrolysis reactor (21), comprises at least two heating chambers (29) which are arranged one after the other and are supplied in parallel.
11. A method for gasifying lumpy fuels, wherein the lumpy fuels are subjected to pyrolysis in a pyrolysis reactor (2) and are subsequently gasified into a product gas, wherein the product gas formed by gasification is supplied to a gas motor (6), wherein exhaust gases of the gas motor (6) are guided to an afterburning combustion chamber (7) and are heated there by means of a burner, and wherein exhaust gases of the afterburning combustion chamber (7) are guided into the pyrolysis reactor (2).
12. A method according to claim 11, characterized in that the exhaust gases of the gas motor (6) are heated in the afterburning combustion chamber (7) to a temperature greater than 800°C.
13. A method according to claim 11 or 12, characterized in that a pyrolysis gas from the pyrolysis reactor (2) is partially oxidised in an oxidation chamber (3), and that the product gas is extracted from pyrolysis coke of the pyrolysis reactor (2) in a reduction furnace (4).
14. A method according to one of the claims 11 to 13, characterized in that the product gas or a foreign gas is selectively combusted in the afterburning combustion chamber (7).
15. A method according to one of the claims 11 to 14, characterized in that before the afterburning combustion chamber (7) nitric oxides are removed from the exhaust gas of the gas motor (6) in an exhaust gas purifying installation (69).

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