AU2010294844B2

AU2010294844B2 - Method for the combined residue gasification of liquid and solid fuels

Info

Publication number: AU2010294844B2
Application number: AU2010294844A
Authority: AU
Inventors: Adrian Brandl; Christoph Hanrott; Max Heinritz-Adrian
Original assignee: ThyssenKrupp Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2009-09-18
Filing date: 2010-09-09
Publication date: 2015-05-07
Anticipated expiration: 2030-09-09
Also published as: CA2774445A1; WO2011032663A3; TWI500755B; ZA201202798B; RU2553156C2; BR112012005838A2; WO2011032663A2; EP2478072A2; AU2010294844A1; DE102009041854A1; UA107470C2; US20120266539A1; RU2012113135A; CN102549117A; KR20120093881A; TW201116616A

Abstract

The invention relates to a method for the common entrained-flow gasification of solid and liquid fuels containing ash, said fuels being fed separately into the coal gasification reactor via several burners and the burners having a concentric firing angle greater than 0°, thus reducing the formation of soot and increasing the conversion rate. The solid fraction is fed together with an inert gas into the gasification reactor. The solid fuel containing ash at least partly contains fine coal particles originating from coal mining that are unsuitable for fixed-bed coal gasification and the liquid fuel containing ash contains residues from a fixed-bed coal gasification.

Description

1 Process for combined residues gasification of liquid and solid fuels [0001] The invention relates to a process for the simultaneous gasification of solid fuels and ash-containing liquid fuels under pressure, the solid fuel and the liquid fuel being fed separately of each other to the gasification reactor and the ash content 5 of both fuels being discharged from the reactor as molten slag at a temperature above 15000C. State of the art [0002] Since many years different gasifier types have been known for the gasification of solid carbonaceous fuels under pressure. The best known processes 10 are fixed-bed, fluidised-bed and entrained-bed gasification. Before the 80s gasification project designs had almost exclusively been based on the fixed-bed gasification process whereas today's units are usually designed as entrained-bed gasifiers. Most of the installed fixed-bed gasifiers are still in operation today. [0003] In comparison to today's entrained-bed gasification processes the fixed 15 bed gasification has some disadvantages, such as increased water and space requirement and the more complex gas and water treatment. Furthermore, in fixed bed gasification, tar oils with fine-grained ash particles are obtained as liquid residue product. These residues may in addition contain phenols, fatty acids, heavy metals, ammonia and other impurities. Therefore, the residues must be treated in a complex 20 way. Furthermore, in coal mining large amounts of fine coal particles are obtained (approx. 20 - 30% of the total amount of coal). This fine coal dust cannot be used for fixed-bed gasification at all or only after complex treatment. In most cases, however, these residues are not useful in the generation of syngas and are passed to a simple combustion unit. 25 [0004] As mentioned in DE 42 26 034 B4 and DE 43 17 319 C1, the liquid residues from the fixed-bed gasification are passed as slurry to the entrained-bed gasification. A technical solution for the gasification of residues in the entrained-bed gasification is not mentioned. An optional utilisation of fine coal particles obtained from coal mining is not mentioned either. 30 [0005] The abstract of DE 42 26 015 C1 mentions the direct process coupling of fixed-bed gasification and oil gasification. However, the oil gasification is only rated for liquid hydrocarbons of a very low concentration of solids or ash, well below one 2 percent by weight. The liquid residues of the fixed-bed gasification, however, contain up to 10% solid particles. The gasification temperatures in the oil gasification are considerably below those of an entrained-bed gasification of coal. This means that any ash particles contained in the fuel continue to be separated as ash and must be 5 disposed of in a complex way. Temperatures above 1400*C, preferably above 1500*C, are required for a separation of the ash particles contained in the residues in molten state from the fixed-bed gasification. The bricklining of the oil gasification unit and the downstream syngas cooling units are not designed for such temperatures. [0006] Thus, only the coal gasification process is suited for a gasification of the 10 residues including the withdrawal of the molten slag. As mentioned in DE 38 20 013 Al, there are coal gasification processes using either a bricklined or a cooled reactor. As explained in DE 38 20 013 Al, a gasifier equipped with a bricklined reactor is also not suited for the gasification of dust-containing tar residues because the forming liquid slag infiltrates and destroys the refractory masonry of the reactors, in particular, 15 in the case of high concentrations of heavy metals or alkali metals in the residues. [0007] Therefore, it is suggested in DE 38 20 013 Al to degas the dust containing tar residues in a gasifier equipped with a cooled reactor vessel, the tar residues being fed - independently of the burner - to the reactor together with the steam, i.e. not in a burner having its own oxygen supply. In this process, however, 20 the input of liquid residues is very limited. In addition, in this process, a considerably lower conversion efficiency is to be expected because there is no intensive mixing of the tar residues and the oxygen. [0008] A further disadvantage of the processes described in DE 42 26 034 C1 and DE 43 17 319 B4 is the limited ash concentration in the fuel. The solid fuel is fed 25 to the gasifier as a fuel/water mixture. The supplied water and the ash content must be brought to the required gasifier temperature with the aid of the energy released in fuel gasification. With high ash contents, however, the energy released by gasification is no longer sufficient to maintain the gasifier temperature. As, however, high-ash coal is used in particular in fixed-bed gasification, the combination of an 30 entrained-bed gasification with coal/water supply is very limited. [0009] In addition, the problem of a possible soot formation in the gasification of liquid hydrocarbons is not mentioned in none of the patents. As the downstream plant sections of the coal gasification are not rated for a higher soot load, an increased soot formation would result in considerable problems in these plant 35 sections.

3 [009a] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. Objectives 5 [009b] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. [0010] It is an objective of preferred forms of the invention to flexibly use the ash containing liquid residues from a fixed-bed gasification and the fine coal particles which cannot be used in a fixed-bed gasification jointly in an entrained-bed gasification and to 0 simultaneously minimise soot formation. [0011] The invention attempts to achieve the objectives by a process according to the features of the first claim. [0012] The dependent claims disclose an advantageous embodiment of the claims. [001 2a] According to a first aspect, the present invention provides a process for the 5 recovery of syngas by the gasification of ash-containing liquid residues from a fixed-bed gasification as fuel at a pressure of 0.3 to 8.0 MPa and a temperature above 14000C using oxygen-containing gaseous gasification agents in a cooled reactor for entrained flow gasification, wherein 20 e the ash-containing liquid and the ash-containing solid fuel are fed to the entrained flow gasification reactor separately via several burners, and * in the entrained flow gasification reactor, the ash-containing liquid fuel together with the ash-containing solid fuel is converted to synthesis gas, and 25 e the ash-containing liquid and the ash-containing solid fuel are fed to the entrained flow gasification reactor secantly to the circumference of the entrained flow gasification reactor at a firing angle above 00, and * the ash-containing solid fuel, dispersed in a transport gas is fed to the entrained flow gasification reactor, and 30 0 the ash-containing solid fuel constitutes a portion of fine coal particles from a coal mine, wherein said fine coal particles have a grain size of below 5 mm.

3a [001 2b] According to a second aspect, the present invention provides a syngas when produced by the process according to the first aspect. [0013] The inventive solution provides a process for the recovery of syngas by the gasification of ash-containing liquid residues from a fixed-bed gasification at a pressure of 0.3 5 to 8.0 MPa and a temperature above 14000C using oxygen-containing gaseous gasification agents in a cooled reactor, in which * the ash-containing liquid fuel is fed to the reactor together with an ash containing solid fuel, and 0 0 the liquid and the solid fuel are fed separately to the reactor via several burners, and * the liquid and the solid fuel are fed to the reactor secantly to the circumference of the reactor at a firing angle above 00, and * the ash-containing solid fuel, dispersed in a supplied gas, is fed to the 5 reactor, and * the ash-containing solid fuel constitutes at least part of the portion of fine coal particles from coal mining which cannot be used for fixed-bed gasification. [0014] Normally, coal lumps from coal mining are gasified in a fixed-bed gasification. 20 Fine coal particles below 5 mm cannot be gasified in the fixed-bed gasification and must be gasified in a different way or disposed of. The fixed-bed gasification additionally yields a mixture of condensates as residue, said mixture containing mainly phenols, fatty acids, ammonia, tar oils and medium-heavy oils as well as ash-containing and carbonaceous solid particles. The residue must be treated in a complex way such that it can be passed to further 25 use if required or be disposed of.

4 [0015] Thus, economic operation of a fixed-bed gasification requires a flexible use of the solid and liquid residues obtained from fixed-bed gasification. For this, an entrained-bed gasification with cooled reactor and a separate supply of the ash containing liquid and solid fuels, the latter being conveyed in a transport gas, is an 5 ideal solution. In an optional embodiment the transport gas consists of 100% or less nitrogen or carbon dioxide or a combination of both gases. [0016] The cooled reactor can be operated at temperatures above 14000C, preferably above 1500 0 C such that the ash-containing fuel particlesO can be discharged as granulated slag. The slag requires no further treatment because 10 possible impurities are not washed out in contrast to the ash in the fixed-bed gasification. Moreover, the cooled reactor is resistant to any impurities contained in the fuels, e.g. heavy metals. [0017] The separate supply of the solid and liquid fuels facilitates the optimum use of the fuels. Typically, the carbonaceous solid fuel is a coal of a fine grain size, 15 preferably below 5 mm, which cannot be used in a fixed-bed gasification. Therefore, the fine coal particles from coal mining which are not suitable for fixed-bed gasification can advantageously be used for being conveyed in a transport gas since a diameter below 0.1 mm is required for conveying the coal in a transport gas. This reduces the normal expenditure by coal grinding.. Moreover, the separate supply of 20 the solid fuel facilitates a compensation of possible variances in quality or quantity of the liquid fuel. Moreover, additional coal may be mixed to the solid fuel to increase the overall performance. [0018] On the other hand, a burner which largely reduces soot formation may be used for the ash-containing liquid fuel. Such a burner is described in EP 00 95 25 103 Al. This burner consists of three tubes arranged concentrically which form a central supply tube and two enclosing annular gaps, the liquid fuel being supplied via the central annular gap formed by the inner and the outer tube. The oxygen or oxygen-containing gas is supplied via the supply tube and the outer annular gap. In a typical embodiment the burner system consists of three concentric tubes with 30 conically tapered end finely distributing the escaping fuel upon exit. This increases the conversion efficiency and thus reduces soot formation to a minimum. The burner system can be equipped with a cooling chamber in the area of the burner outlet. [0020] The carbonaceous solid fuel is preferably conveyed via two burner systems facing each other and, staggered by 90 degrees in relation to these in the 35 horizontal, the ash-containing liquid fuel is also supplied via two burner systems facing each other. Of course, the burner systems may also be provided in any other 5 number and thus also be staggered by an angle greater or smaller than 90 degrees. Burner planes arranged in parallel are also feasible for performance adaptation. [0021] A further reduction of soot formation is achieved by all burners having a firing angle greater than 0 degree and preferably 3-6 degrees, a swirl thus being 5 created inside the reactor. This increases, on the one hand both the residence time and the conversion efficiency, the firing angle being the angle between the discharge direction of the fuel and the horizontal connection line between the burner nozzle and the axis of symmetry of the reactor. The discharge direction of the fuel may also be inclined towards the horizontal if necessary. On the other hand, the separation of the 10 molten slag and of the non-converted carbon particles towards the reactor wall is intensified. There, the non-converted carbon particles are further converted or retained in the slag. [0022] It is also possible to provide several horizontal planes for the burners. Hence, the burner systems can be distributed over one or several horizontal planes. 15 Normally, the firing angle relative to the horizontal plane is 0 degree. However, it is also possible that the firing angle relative to the horizontal plane is greater than 0 degree. Embodiment examples [0023] The following example is to explain the invention. The embodiment 20 example is shown in figures 1 to 3 and detailed in the following sections. FIG. 1 shows an inventive process of a fixed-bed and an entrained-bed gasification. FIG. 2 shows the lateral and vertical view of a gasifier including burners for solid and liquid fuels. FIG. 3 shows a burner suited for running the inventive process. The drawings only show embodiment examples of the invention, the invention not being restricted 25 to these embodiment examples. [0024] In a preferred embodiment, the residues of a fixed-bed gasification are conveyed to an entrained-bed gasifier. Here, the residues are a liquid tar/fine coal mixture obtained as residue from the fixed-bed gasification and non-usable fine coal particles from coal mining. 30 [0025] Every hour 400 t/h of coal are extracted from a coal mine (1), Fig. 1. Of these, approx. 280 t/h of lumpy coal (1a) are suited for fixed-bed gasification (2). Synthesis gas (2a) is produced in the fixed-bed gasification (2). The remaining fine coal (1b) has a diameter lower 5 mm and cannot be used for fixed-bed gasification (2). The remaining 120 t/h of fine coal (1b) are conveyed to the entrained-bed 35 gasification (3) and there converted to synthesis gas (3a). In addition, the fixed-bed 6 gasification (2) yields approx. 95 t/h of fine-coal-containing tar oils to be further conveyed (2b) to the entrained-bed gasification (3). The solid carbon content of the tar oils is approx. 5%. The amount of energy of 95 t/h of the residue product roughly corresponds to 25% of the amount of energy supplied to the fixed-bed gasification 5 via the 280 t/h of lumpy coal. [0026] Thus, the total amount of synthesis gas produced can be increased by the described combination of fixed-bed and entrained-bed gasification from 270,000 Nm 3 /h to 490,000 Nm 3 /h. [0027] In the preferred embodiment, Fig. 2, the residues from the fixed-bed 10 gasification and the fine coal are fed separately via four burners to the gasification reactor (4) of the entrained-bed gasifier. Two burners are provided for the solid fuel (5a,5c) and two burners for the liquid fuel (5b,5d). All burners (5a-d) are in a horizontal plane, two burners each facing each other. The burners are designed in such a manner that the fuel escapes from the burners (10) secantly to the 15 circumference of the reactor, the firing angle (9) between the discharge direction of the fuel (11) and the connection line between the burner nozzle and the axis of symmetry of the reactor being greater than 0 degree, preferably 3-6 degrees. [0028] Fig. 3 shows the preferred burner for the gasification of the tar oils of fine coal content. This burner consists of three tubes arranged concentrically (6,7,8) 20 which form a central supply tube (6) and two enclosing annular gaps (7,8), the liquid fuel being supplied via the central supply tube (6). The fuel is supplied via the annular gap (7). The oxygen-containing gas is supplied via outer supply tube (8). The three tubes have a conically tapered end finely distributing the escaping fuel upon exit. This increases the conversion efficiency and reduces soot formation to a 25 minimum. [0029] List of references used 1 Coal mine la Lumpy coal 1b Fine coal 2 Fixed-bed gasification 2a Synthesis gas 3 Entrained-bed gasification 3a Synthesis gas 4 Gasification reactor 7 5a-d Burners 6 Central supply tube 7 Annular gap 8 Outer supply tube 9 Firing angle 10 Transversal discharge 11 Radial discharge

Claims

1. Process for the recovery of syngas by the gasification of ash-containing liquid residues from a fixed-bed gasification as fuel at a pressure of 0.3 to 8.0 MPa and a temperature above 14000C using oxygen-containing gaseous gasification agents in a cooled reactor for entrained 5 flow gasification, wherein * the ash-containing liquid and the ash-containing solid fuel are fed to the entrained flow gasification reactor separately via several burners, and * in the entrained flow gasification reactor, the ash-containing liquid fuel together 0 with the ash-containing solid fuel is converted to synthesis gas, and * the ash-containing liquid and the ash-containing solid fuel are fed to the entrained flow gasification reactor secantly to the circumference of the entrained flow gasification reactor at a firing angle above 00, and * the ash-containing solid fuel, dispersed in a transport gas is fed to the entrained 5 flow gasification reactor, and * the ash-containing solid fuel constitutes a portion of fine coal particles from a coal mine, wherein said fine coal particles have a grain size of below 5 mm.

2. Process according to claim 1, wherein the ash-containing liquid fuel is a tar provided by fixed-bed gasification, wherein said tar comprises 25% of the amount of energy supplied to the 0 fixed-bed gasification via coal with a grain size of above 5 mm.

3. Process according to claim 1 or 2, wherein the residue product from the fixed-bed gasification contains hydrocarbons, tars, phenols, fatty acids and ammonia.

4. Process according to any one of claims 1 to 3, wherein the burners for the supply of the ash-containing liquid fuel consist of three tubes arranged concentrically, oxygen or an oxygen 25 containing gas being conveyed through the inner and the outer tube of the burners and the ash-containing liquid fuel being conveyed through the central annular gap formed by the inner and the outer tube.

5. Process according to claim 4, wherein the burners including the three tubes concentrically arranged have a conically tapered end and is equipped with a cooling chamber 30 in the area of the burner outlets. 9

6. Process according to any one of claims 1 to 5, wherein the ash-containing solid fuel is supplied via two or more burners facing each other and, staggered by 90 degrees in relation to these in the horizontal, the ash-containing liquid fuel is supplied via two or more burners facing each other. 5

7. Process according to any one of claims 1 to 6, wherein the burners are distributed over one horizontal plane.

8. Process according to any one of claims 1 to 6, wherein the burners are distributed over several horizontal planes.

9. Process according to any one of claims 1 to 8, wherein the firing angle between the 0 discharge direction of the fuel and the connection line between the burner nozzle and the axis of symmetry of the reactor is 3-60.

10. Process according to claim 7, wherein the firing angle opposite the horizontal plane is greater than 0 degree.

11. Process according to claim 1, wherein the transport gas consists of 100% or less of 5 nitrogen or carbon dioxide or a combination of both gases.

12. A syngas when produced by the process according to any one of claims 1 to 11.

13. Process for the recovery of syngas; a syngas, substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.