WO2018024404A1 - Facility and method for transforming carbon-containing fuels into synthesis gas - Google Patents

Abstract

The invention relates to a facility for transforming carbon-containing fuels into synthesis gas, comprising a reactor (10) comprising at least one fluidised bed zone (11) in which a gasification of the fuels is carried out by a gasification agent, and at least one region (12) arranged in the flow path downstream of the fluidised bed zone (11), in which a post-gasification of the fluid flow leaving the fluidised bed zone (11) is carried out by means of at least one plasma torch (13). According to the invention, the at least one plasma torch (13) is arranged such that the flame thereof is released into the reactor (10) which comprises the fluidised bed zone (11). The invention relates to a facility for transforming carbon-containing fuels into synthesis gas, by means of which different feedstock can be gasified in a fluidised bed optionally at high pressures with a high level of safety and availability. The use of a plasma burner (13) allows an improved transformation of the volatile substances and saves using oxygen, the costly gasification agent which is otherwise used during the post-gasification.

Description

 Plant and process for the conversion of carbonaceous fuels into synthesis gas

description

TECHNICAL AREA

 The present invention relates to a plant for the conversion of carbonaceous fuels into synthesis gas comprising a reactor having at least one fluidized bed zone in which the gasification of the fuels by gasification agent, and at least one downstream in the flow path of the fluidized bed zone, in which by means of at least one plasma torch a gasification of takes place from the fluidized bed emerging fluid stream.

BACKGROUND

 Processes for converting carbonaceous fuels in the fluidized bed have long been known. In particular, here is the high-temperature Winkler method (HTW method) to call, which is considered a proven technology with which both lumpy and liquid or pasty fuels are converted into synthesis gas. As a fuel also difficult fuels with a very high proportion of ash and biologically based fuels are used. These are introduced into a fluidized bed, which is operated as a bubbling fluidized bed, and gasified with oxygen. The HTW process works in comparison to other gasification processes at comparatively moderate temperatures, at which the resulting ash does not leave the gasification reactor in a molten state. This has operational advantages, especially with corrosive ashes.

In the known HTW process gasification is usually done via separate nozzles with the gasification agents, such as water vapor, carbon dioxide, oxygen or air. These nozzles are arranged, for example, in different planes, for example both in the fluidized bed zone and in the so-called freeboard zone (FB). In this freeboard zone (FB) a high material and energy transfer rate is achieved and the return of the unreacted solids over the cyclone and return line in the fluidized bed, a uniform temperature distribution over the fluidized bed can be secured. To avoid the formation of particle agglomerations, the temperature of the fluidized bed should be kept below the temperature of the ash softening point.

In addition, in the conventional HTW process gasification agent, usually oxygen, in the FB zone, which is located above the fluidized bed, registered. By the Injection of this "secondary" oxygen, various effects are achieved, namely on the one hand, the implementation of a portion of finely divided fuel, which is discharged from the fluidized bed and on the other hand, the temperature of the gases to be increased, so that further oxidation and / or cracking the volatiles (tars and hydrocarbons) evolved from the feedstock can react, while the fine dispersed fuel particles react with steam and CO2.

The proportion of the total oxygen above the fluidized bed is, for example, between about 40% and about 10% in an HTW process. To avoid slagging in the post-gasification zone, temperatures should preferably not exceed certain limits, and preferably the operating temperature should be at least about 100 ° C below the ash softening point. For this one can mix steam with oxygen and bring it into the reactor. However, the addition of oxygen to the post-gasification zone results in partial combustion of the synthesis gas reservoir (CO + H ₂ ) and consequent reduction of the synthesis gas yield.

In principle, plasma gasification is known from the prior art. For example, US Pat. No. 5,958,264 describes a process for the gasification of combustible waste, in which the ash is glazed from a preceding gasification process in a further furnace in which an arc plasma is generated. Such a plasma furnace operates at very high temperatures of up to 1700 ° C, so that the ash is melted. Due to the high temperatures, the external steel oven must be lined with a refractory material. About the arc electrodes, a plasma is generated in the entire furnace here. The known process is two-stage and uses two separate reactors / ovens. The ashes from the first process step must be transferred from the top to the second oven, where the glazing takes place. In addition, from this furnace in which the plasma is produced, the molten slag must be removed in the lower area. The method is therefore complex in terms of apparatus and requires a high energy input.

DE 35 37 758 AI describes a coal gasifier with a fluidized bed, wherein the gas is discharged via an outlet and returned via the lines back into the carburetor and wherein also via a line oxygen is supplied. In this document, the possibility is mentioned, the gasification agent by a Preheat plasma torch. This makes it possible to preheat recycled process gas in this way and to use for heat input into the carburetor. The plasma torch used for this purpose is thus located outside the reactor in which the fluidized bed gasification takes place. The gas leaving the fluidized-bed reactor is passed through a hot cyclone for the separation of dust and then returned to the reactor via a conduit at the level of the fluidized bed. The gasification of the dust is carried out by means of a line supplied oxygen. The reactor is formed here continuously from bottom to top widening conically.

EP 0 153 235 B1 likewise describes a process for the production of synthesis gas, in which the gasification first takes place at a moderate temperature of 700 to 800 ° C., working in a fluidized bed. To subsequently increase the synthesis gas content, a second so-called conversion reactor is used, in which the exhaust gases are introduced from the gasification reactor. As can be seen in Figure 2 of this document, the injected gas is brought to a very high temperature at the entrance of the conversion reactor, to which a plasma torch can be used. The temperature can thereby be brought to 3000 to 5000 ° C in the inlet zone of the second reactor. The second conversion reactor is used in this known method to reduce the proportion of methane and higher hydrocarbons contained in the synthesis gas by reaction with water vapor also contained in the gas stream. The temperature in the conversion reactor is 1200 ° C to 1500 ° C. The disadvantage, however, is that it increases the CGr content in the gas. In this document, it is further proposed, on the one hand, to introduce the gas stream from the fluidized bed gasification into the conversion reactor and, on the other hand, to heat another gas via a plasma torch to a very high temperature and to inject it into the conversion reactor. The injected additional gas may be hydrogen or nitrogen. Since two separate reactors are used in this known plant, there is a higher expenditure on equipment.

Further arrangements, in particular fluidized-bed reactors, as well as other types of gasification agent feed are described in the publications DE 10 2007 006 982 B4, AT 503 517 A1, DE 10 2011 051 906 A1, DE 10 2013 107 311 A1 or EP 1 201 731 A1 described.

DESCRIPTION OF THE INVENTION The object of the present invention is to provide a plant and a corresponding process for the conversion of carbonaceous fuels into synthesis gas having the features of the aforementioned type, by means of which different feedstocks in a fluidized bed optionally gas at higher pressures with high safety and availability let and which work economically.

The solution of this object provides a plant for the conversion of carbonaceous fuels in synthesis gas with the features of claim 1 and a method having the features of claim 9.

In the system according to the invention, at least one plasma torch is arranged such that its flame is discharged into the reactor which has the fluidized bed zone. The plant thus comprises a reactor in which both the fluidized bed gasification takes place as well as the gasification by means of at least one plasma torch. The fluidized-bed gasification may also take place by means of at least one plasma burner. The use of a plasma burner gives a better conversion of the volatile substances, but saves the gasification agent oxygen. Since both processes run in only one reactor, this is achieved with a reduced expenditure on equipment.

The costs of producing pure oxygen in a conventional HTW gasification process are extremely high and therefore significantly affect the economics of the HTW gasification process. Pure oxygen is obtained, for example, by cryogenic air separation. The supplied air must be filtered, compressed and cooled to approx. - 185 ° C. The liquefied air stream must then be distilled in distillation towers. Thereafter, the separation takes place depending on the boiling point in individual components. Therefore, the solution according to the invention is advantageous because the otherwise used oxygen lances can be completely or partially replaced by plasma torches in the inventive method.

Preferably, according to a development of the invention, the region in which the gasification takes place is arranged in the same reactor above the fluidized bed zone. This makes it possible to work with two different temperature zones in one reactor, wherein the temperature in the fluidized bed zone is lower than in the region of the post-gasification. According to a preferred embodiment of the invention, the at least one plasma torch, for example, at least partially disposed in the wall of the reactor, which also has the at least one fluidized bed zone.

For example, the plasma burner (s) may be arranged such that the plasma / flame is discharged into the reactor in an approximately radial direction with respect to the reactor and / or approximately transversely to the flow direction of the fluid in the region of the post-gasification.

The plasma torch (s) is / are preferably arranged such that the plasma / flame is released into the reactor above the fluidized bed zone. The fluid flow exiting from the fluidized bed zone upwards (generally axially relative to the reactor) is then preferably acted upon by the flame of the plasma burner approximately transversely to its direction of flow.

Preferably, the region of the reactor in which the gasification takes place, is approximately cylindrical and / or the reactor is in the region of the fluidized bed zone approximately conically widening in the flow direction of the fluid.

A preferred embodiment of the invention provides that the system comprises a downstream in the flow path the region in which the gasification takes place cyclone separator. After passing through the region of the post-gasification, a separation of solids can then take place in this cyclone separator, and subsequently the thus purified fluid stream can be returned to the fluidized bed zone via a return line leaving the cyclone separator, which discharges into the fluidized bed zone of the reactor, so that both the Be traversed area of the fluidized bed and the gasification zone.

The present invention further relates to a process for the conversion of carbonaceous fuels in synthesis gas, wherein in a reactor having at least one fluidized bed zone, a gasification of the fuels by gasification, wherein in at least one downstream in the flow path of the fluidized bed zone by means of at least one plasma burner, a gasification of According to the invention, the gasification by means of the at least one plasma burner takes place in the reactor, which comprises the fluidized-bed zone. Preferably, according to the invention, the gasification in the region which is acted upon by at least one plasma torch, at a higher temperature than the gasification in the fluidized bed zone.

For example, the gasification takes place in the fluidized bed zone at a temperature of about 750 ° C to 850 ° C and the gasification at a temperature higher by at least about 100 ° C, preferably at a temperature of at least about 900 ° C, more preferably at a temperature in Range from about 950 ° C to about 1200 ° C. Thus, two different temperature zones are formed, namely the fluidized-bed zone with temperatures of, for example, around 800 ° +/- about 50 ° C. and the post-gasification zone with, for example, about 1000 ° C. +/- about 100 ° C.

According to a preferred embodiment of the invention, the flame of the plasma torch, for example, a maximum temperature in the flame kernel of about 3500 ° C to about 4500 ° C.

In the method according to the invention, according to a preferred development of the invention, the at least one plasma torch can be operated with at least one reducing and / or at least one oxidizing gas.

For example, the at least one plasma torch may be operated with a fluid stream comprising at least one of the fluids selected from steam, air, oxygen, nitrogen and CO2. The use of steam is advantageous because its production is particularly cost-effective, and it is particularly reactive. The flame of the plasma torch contains radicals such as 0, H, OH, O ₂ , H ₂ and H ₂ O and a temperature of, for example, in the range of about 4000 ° C. As a result of the very hot local flame temperature and the high supply of highly reactive radicals, tars and hydrocarbons can be cracked. In addition, the increased synthesis gas temperature and the conversion of the bed material are positively influenced by the heterogeneous reaction of steam and C0 ₂ .

The plasma temperature can preferably be controlled by injecting steam and / or C0 ₂ in the region of the plasma burner.

In the method according to the invention, the gasification is preferably carried out in a pressure-charged fluidized bed, wherein the gasification in the fluidized bed zone preferably at a pressure of at least about 1 bar, in particular of at least about 5 bar to about 40 bar.

DESCRIPTION OF THE FIGURES

 Hereinafter, the present invention will be described in more detail by way of embodiments with reference to the accompanying drawings. Show

Figure 1 is a schematically simplified view of a system according to the invention in partial longitudinal section;

Figure 2 is an enlarged detail of a detail II of Figure 1;

FIG. 3 shows a schematically simplified illustration of a plasma burner which can be used in the context of the present invention.

DETAILED DESCRIPTION OF THE FIGURES

 In the following, reference will first be made to FIG. 1 and on the basis of which the basic structure of a system according to the invention will be explained by way of example. The plant comprises a reactor 10, in which the gasification of the carbonaceous fuels takes place. This reactor 10 comprises a fluidized bed zone I I in a lower conically widening section. The fuel is supplied to the fluidized bed, for example via a supply device 17 arranged laterally there, which is indicated here only schematically by an arrow. In the area of this fluidized bed zone 11, in which the gasification of the fuels takes place, various feed devices such as lines and / or nozzles are further provided on the reactor 10, by means of which the supply of the gasification agent takes place, these feeders are only schematically indicated by arrows. These are for example a plurality of feed devices 18 a, 18 b for oxygen and / or steam, which may be arranged at different height intervals to the lower end of the fluidized bed zone 11 and spaced from each other on the reactor 10.

Furthermore, a feed device 19 for CO2, for example, in the lower end of the fluidized bed zone 11 is provided, with multiple accesses for CO2 may be present. In particular, one or two ash deductions for the supply of CO2 can be provided in the fluidized bed. At the upper end of the fluidized bed zone 11, the first continuous conically widening upward shape of the reactor 10 in a cylindrical region 12 with then in the flow direction constant cross section over. In this cylindrical portion 12, the gasification takes place. For this purpose, for example, in the wall 14 of the reactor 10 in the region 12 a plasma torch 13 is arranged, which emits its flame approximately in the radial direction in the interior of the reactor 10 into it, so that the flame of the plasma torch 13 approximately in the transverse direction relative to the axial flow of the Fluid which flows in the reactor in the region of the gasification in the longitudinal direction of the reactor 10 upwards. At the upper end of the fluid flow exits the reactor from the side and passes through a connecting line 21 into a cyclone separator 15, in which a separation of solid fractions can be done. The separated solids emerge downwards from the cyclone separator 15 and flow back via the return line 16, this return line 16 discharging downstream in the area of the fluidized bed zone 11 into the reactor 10, so that the separated solids are reintroduced into the fluidized bed zone and there again a Gasification can be supplied.

At the upper end of the cyclone separator, as indicated by the arrow 22, the purified gas stream can be removed from the circulation.

FIG. 2 shows an enlarged detail view of the section of FIG. 1 designated by II. In FIG. 2, the plasma torch 13 in the wall 14 of the reactor can be seen on an enlarged scale, the plasma torch 13 being illustrated only schematically here. It can be seen that the flame / plasma 23 enters the interior of the reactor from the lateral wall 14 in approximately a radial direction, preferably at a certain distance above the upper end of the fluidized bed zone 11 of the reactor 10.

The construction of a plasma burner 13 which can be used by way of example in a system according to the present invention will be explained in more detail below with reference to FIG. This comprises an approximately cylindrical housing 24, for example, in which a ring-shaped electrode 26 is supplied via a power supply device 25. This electrode concentrically surrounds a magnet 30, which generates a magnetic field. Furthermore, an example, approximately annular cooling device 27 is provided for the cooling of the magnet 30. Inside the annular electrode 26, a plasma column 31 is generated. The inside of the housing 24 is supplied from the outside radially a process gas 28, which then flows with the plasma column 31 in the axial direction in the housing and enters a nozzle 29, from which then the hot process gas, as indicated by the arrows 23 in Figure 3, emerges. Such a hot process gas then passes as a flame 23 of the plasma torch 13, as described above with reference to Figure 2, in the reactor 10th

LIST OF REFERENCE NUMBERS

 10 reactor

 11 fluidized bed zone

 12 Re-gasification area

 13 plasma torches

 14 wall of the reactor

 15 cyclone separator

 16 return line

 17 Feed device for fuel

 18a Feeders for oxygen and / or steam

18b Feeders for oxygen and / or steam

19 feeder for C0 ₂

 20 feeder for steam

 21 connection line

 22 arrow

 23 plasma / flame

 24 housing

 25 power supply device

 26 electrode

 27 cooling device

 28 process gas

29 nozzle Magnetic plasma column

Claims

claims 1. plant for the conversion of carbonaceous fuels into synthesis gas comprising a reactor (10) having at least one fluidized bed zone (11), in which the gasification of the fuels by gasification agent, and at least one in the flow path of the fluidized bed zone (11) downstream region (12), in which by means of at least one plasma torch (13) a subsequent gasification of the fluid stream emerging from the fluidized bed zone (11), characterized in that the at least one plasma torch (13) is arranged such that its flame in the reactor (10), which the fluidized bed zone has (11), is discharged into it. 2. Plant for converting carbonaceous fuels into synthesis gas according to claim 1, wherein the region (12), in which the gasification takes place, in the same reactor (10) above the fluidized bed zone (11) is arranged. 3. Plant for the conversion of carbonaceous fuels in synthesis gas according to claim 1 or 2, wherein at least one plasma torch (13) at least partially in the wall (14) of the reactor (10) is arranged, which has the at least one fluidized bed zone (11). The carbonaceous fuel conversion plant of synthesis gas according to any one of claims 1 to 3, wherein the plasma burner (13) is arranged such that the plasma / flame is approximately radial with respect to the reactor and / or approximately transverse to the flow direction of the fluid is discharged into the reactor in the field of Nachvergasung. The carbonaceous fuel conversion plant of synthesis gas according to any one of claims 1 to 4, wherein the plasma burner (13) is arranged to discharge the plasma / flame above the fluidized bed zone (11) into the reactor. The carbonaceous fuel conversion plant of synthesis gas according to any one of claims 1 to 5, wherein the region (12) of the reactor (10) in which the Re-gasification takes place, is approximately cylindrical and / or the reactor (10) in the region of the fluidized bed zone (11) is approximately conically widening in the flow direction of the fluid 7. plant for the conversion of carbonaceous fuels in synthesis gas according to one of claims 1 to 6, wherein said in the flow path to the region (12), in which the gasification takes place downstream cyclone separator (15). 8. Plant for the conversion of carbonaceous fuels in synthesis gas according to claim 7, wherein from the cyclone separator (15) on the output side outgoing a return line (16) is arranged, which in the fluidized bed zone (11) of the reactor (10) opens. 9. A process for the conversion of carbonaceous fuels in synthesis gas, wherein in a reactor (10) having at least one fluidized bed zone (11) gasification of the fuels by gasification agent, wherein in at least one in the flow path of the fluidized bed zone (11) downstream region (12) at least one plasma torch (13) is provided with a subsequent gasification of the fluid stream emerging from the fluidized bed zone (11), characterized in that the gasification takes place by means of the at least one plasma torch (13) in the reactor (10) comprising the fluidized bed zone (11). 10. A process for converting carbonaceous fuels to synthesis gas according to claim 9, wherein the regasification in the region (12) occurs at a higher temperature than the gasification in the fluidized bed zone (11). A process for converting carbonaceous fuels to synthesis gas according to claim 10, wherein the gasification in the fluidized bed zone (11) is at a temperature of about 700 ° C to 900 ° C and the gasification in the region (12) is at least about 100 ° C higher temperature, preferably at a temperature of at least about 900 ° C, more preferably at a temperature in the range of about 950 ° C to about 1200 ° C. 12. A process for converting carbonaceous fuels into synthesis gas according to any one of claims 9 to 11, wherein the flame of the plasma torch has a maximum temperature of about 3500 ° C to about 4500 ° C. 13. A process for the conversion of carbonaceous fuels into synthesis gas according to any one of claims 9 to 12, wherein the at least one plasma torch (13) is operated with at least one reducing and / or at least one oxidizing gas. 14. A process for converting carbonaceous fuels into synthesis gas according to any one of claims 9 to 13, wherein the at least one plasma torch (13) is operated with a fluid stream comprising at least one of the fluids selected from steam, air, oxygen, nitrogen and CO2. 15. A process for the conversion of carbonaceous fuels in synthesis gas according to any one of claims 9 to 14, wherein, preferably, in the region of the plasma burner, steam and / or C0 _{2 is} injected to control the plasma temperature. 16. A process for the conversion of carbonaceous fuels in synthesis gas according to any one of claims 9 to 15, wherein the gasification in the fluidized bed zone at a pressure of at least about 1 bar, in particular of at least about 5 bar. A process for converting carbonaceous fuels to synthesis gas according to any one of claims 9 to 16, which is a high temperature Winkler process. 18. A process for the conversion of carbonaceous fuels in synthesis gas according to any one of claims 9 to 17, wherein this is carried out in a plant having the features of one of claims 1 to 8.