JPH0451725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a burner for the gasification of finely divided solid fuels.

Solid fuel gasification involves the partial combustion of a solid fuel with a substoichiometric amount of pure oxygen or an oxygen-containing gas such as air to produce a product gas consisting primarily of carbon monoxide and hydrogen. can be defined as a method of Depending on the composition of the combustion medium, the product gas also contains other substances that may be beneficial or may be considered as pollutants.

Although the invention will be described primarily with reference to pulverized coal, the burner and method according to the invention may include lignite, wood, bitumen,
It should be noted that it is also suitable for other types of solid fuels that can be gasified, such as soot and petroleum coke.

According to well-known gasification methods, solid fuel in a finely divided state is passed along with a carrier gas through a burner toward a reactor section, while a combustion medium is added to the solid fuel stream inside the burner. or separately introduced into the reactor section. that the reactants are effectively mixed with each other;
Great care must be taken. If the reactants do not come into intimate contact with each other, the oxygen and solid fuel will flow into the reactor interior following at least partially independent flow paths. Since the reactor section is filled primarily with hot carbon monoxide and hydrogen, oxygen will react rapidly with these gases instead of solid fuel. The very high temperature combustion so formed produces carbon dioxide and water vapor, which are also separated into independent fuels that have little contact with the relatively cool solid fuel stream. will follow the flow path. Such action of oxygen would create localized hot spots within the reactor, thereby causing damage to the refractory lining of the reactor and reducing the heat flux to the applied burner. )
may increase.

Adequate mixing of the solid fuel and oxygen can be achieved by adding oxygen to the solid fuel within the burner itself. The disadvantage of this method, however, is -
Particularly in high-pressure gasification, burner design and operation are highly critical. The reason for this is that the elapsed time between the moment of mixing and the moment when the fuel/oxygen mixture enters the reactor zone must always be shorter than the combustion induction time of the mixture. On top of that,
To avoid flashback phenomena, the velocity of the mixture in the burner must be greater than the flame propagation velocity. However, upon increasing gasification pressure, the combustion induction time decreases and the flame propagation velocity increases. Furthermore, if the burner is operated at low fuel loads, in other words, if the velocity of the fuel/oxygen mixture in the burner is low, combustion induction times or flashback conditions can easily be reached within the burner itself, resulting in This can cause overheating and severe damage to the burner.

The above problem of premature combustion does not occur if combustion and oxygen are mixed in the reactor area outside the burner. In this case, as mentioned above, special measures should be taken to ensure sufficient mixing necessary for effective gasification of the fuel. The disadvantage of mixing fuel and oxygen outside the burner in the reactor zone is due to the high temperature flame generated by the early contact of the oxygen with the product gases, i.e. carbon monoxide and hydrogen, present in the reactor zone. , the front of the burner overheats. It has been previously proposed to add oxygen as a high velocity jet into the fuel stream to promote intimate mixing of the fuel and oxygen. Such a high speed jet is
However, easy incorporation of reaction gases occurs with the risk of the formation of overheated zones in the reactor space. As already mentioned above, such overheating zones can easily cause damage to the refractory lining of the reactor and the front part of the burner.

One object of the present invention is an improved burner for the gasification of solid fuels, without having the above-mentioned disadvantages associated with fuel/oxygen mixing when using known burners, but with a It is an object of the present invention to provide a burner in which a proper mixing of fuel and oxygen can be achieved.

an oxygen supply passageway and a solid fuel supply passageway disposed coaxially within the oxygen supply passageway, the solid fuel supply passageway being disposed between a central oxygen outlet passageway and an annular oxygen outlet passageway; In a burner for the gasification of finely divided solid fuel, which merges into a solid fuel outlet passage, the oxygen supply passage merges into a central high-velocity oxygen outlet passage and, via a constricted passage, connects a separate solid fuel merging into an annular low-velocity oxygen outlet passageway, said constricted passageway being located at the upstream end of said central high-velocity oxygen outlet passageway or downstream thereof; It relates to a burner for gasification.

The constricted passageway between the central oxygen supply passageway and the tubular low velocity oxygen outlet passageway can be formed in a number of different ways. To promote uniform outflow of oxygen, this constricted passageway preferably has a plurality of passages uniformly distributed over the tubular low velocity oxygen outlet passageway, or coaxially with the annular low velocity oxygen outlet passageway. formed by any of the rings arranged in .

To further reduce the rate of oxygen exit from the low velocity oxygen outlet passage, the annular low velocity oxygen outlet passage is preferably gradually widened in the downstream direction.
In this embodiment, the oxygen velocity in the central oxygen supply passage is selected to be relatively high without affecting the shielding effect of the low velocity oxygen exiting from the low velocity oxygen outlet passage during operation of the burner according to the invention. Rukoto can.

During operation, the low velocity oxygen exiting the low velocity oxygen outlet passage forms a shield around the high velocity oxygen and solid fuel streams, thereby preventing excessive ingestion of hot reactant gases by the high velocity oxygen stream. Drawing hot reactant gases along the burner surface can cause overheating and even damage the burner itself. Apart from forming a protective shield to prevent overheating of the burner front, the low velocity oxygen flow further serves to provide an additional supply of oxygen to complete the gasification of the solid fuel.

The quality of the solid fuel to be gasified sets requirements for the degree of mixing necessary for proper contact of the solid fuel with a gasification medium formed by pure oxygen or an oxygen-containing gas. Depending on the degree of mixing required,
The solid fuel outlet passage may be disposed parallel to the central high velocity oxygen outlet passage or tapered in a downstream direction towards said high velocity oxygen outlet passage.

To achieve optimal effectiveness of the low velocity oxygen shield, the shield should preferably be formed to seal around the solid fuel stream. This means that the annular low velocity oxygen outlet passage and the solid fuel outlet passage should be arranged to follow parallel paths, or in other words, both passages should be placed in the central high velocity oxygen outlet passage. is parallel to
or tapered in the downstream direction.

If the proposed burner is intended for a relatively low throughput of solid fuel, the solid fuel outlet passage may be annular, separating the central high-velocity oxygen outlet passage from the annular low-velocity oxygen outlet passage. It may conveniently be formed by a conduit. The annular conduit has a rather limited thickness to allow all solid fuel particles to contact the oxygen.

In order to complete relatively large throughputs, it is advisable to dispense with the use of annular outlet passages. This is because such an annular shape needs to have a rather large thickness and is therefore not suitable for bringing all the solid fuel particles into contact with oxygen.

If the proposed burner is intended for high throughput, it is therefore expedient to form the solid fuel outlet passage by a plurality of spaced relatively small outlet conduits. One advantage of this embodiment consists in the ability to generate relatively narrow solid fuel streams, each of which is fully surrounded by oxygen. These conduits are preferably uniformly distributed over the tubular element separating the central high velocity oxygen outlet passage from the annular low velocity oxygen outlet passage. The solid fuel outlet conduit may be located on the outside of the tubular element or on its inside surface.

In a modification of the burner according to the invention, the wall of the cylindrical member is provided with holes for passage of the solid fuel.

The solid fuel supply passage is preferably formed by a passage having a cylindrical shape, which passage is arranged centrally inside the oxygen supply passage in order to obtain a symmetrical arrangement inside the burner, which symmetrical arrangement is Convenient for reducing medium vibrations. As is known in the art, the cross-sectional area of the solid fuel outlet passage is preferably selected to be equal to the cross-sectional area of the solid fuel outlet passage in order to prevent the risk of stagnation zone formation in the solid fuel passage.

The oxygen velocity in the central outlet passage should be selected to be sufficiently high to allow for easy dispersion of the solid fuel stream. The preferred rate of central oxygen is
The velocity of the oxygen is selected to be at least 60 m/sec, and even more preferably the oxygen velocity is at least 90 m/sec.
A central high velocity oxygen outlet passageway and a constricted passageway are used to maintain the oxygen flow rate in the oxygen supply passageway at an acceptable level without affecting the required minimum velocity of oxygen in the central outlet passageway. The total cross-sectional area of is preferably substantially equal to the cross-sectional area of the oxygen supply passageway, and even more preferably less than the cross-sectional area of the oxygen supply passageway.

Furthermore, the invention relates to a method for the gasification of finely divided solid fuels, which method is constituted by using one or more burners of the type described above in connection with the invention. When using such burners, the solid fuel to be gasified is introduced into the reactor space downstream of the burner as a ring surrounding a high velocity oxygen stream, while the annular stream of solid fuel itself is introduced into the reactor space as a ring surrounding a high velocity oxygen stream. Surrounded by a protective shield of oxygen.

The oxygen exiting the ring around the solid fuel and the central oxygen passage serves as a combustion medium, among other things, to complete the gasification of the solid fuel. As already mentioned above, the annular low-velocity oxygen stream has the additional function of forming a shield around the solid fuel stream and the central high-velocity oxygen stream, thereby directing the high-velocity oxygen stream to the high temperature This prevents reactive gases from being sucked in along the front of the burner. The low-velocity oxygen shield further inhibits the escape of solid fuel, thereby reducing the exchange rate,
That is, the amount of solid fuel converted into useful production gas relative to the amount of solid fuel supplied is advantageously influenced.

In order to achieve sufficient suppression of hot reaction gas ingestion along the burner front,
The velocity of the annular low velocity oxygen stream is preferably at most 50 m/sec, even more preferably at most 30 m/sec.

Apart from gasification purposes, the central oxygen stream has the primary function of helping to disperse the solid fuel stream. The central oxygen velocity should preferably be on the order of at least about 60 m/sec to provide sufficient momentum to disperse the solid fuel stream. Even more preferably, the central oxygen flow has a velocity of at least 90 m/sec.

A moderator gas may be added to the oxygen passing through the oxygen supply passage to maintain the reactor temperature at an acceptable level. The regulating gas may be, for example, water vapor, carbon dioxide,
It can be formed by nitrogen and a cooled reactant gas.

The invention will now be further explained with reference to the accompanying drawings, in which: FIG.

It should be noted that the present invention is not limited in any way by the description based on these drawings.

Figures 1 and 2 of the drawings represent a first embodiment of a burner according to the invention, generally designated by the reference numeral 1, which is used for the gasification of finely divided solid fuels such as pulverized coal. The purpose is to Said burner 1 constitutes a hollow wall member 2 of substantially cylindrical shape and cooled on the inside, said wall member having an enlarged end forming a burner front face 3 and having an enlarged end. The burner front surface extends substantially perpendicular to the longitudinal axis 4 of the burner.
A concentric partition wall 5 is provided inside the hollow wall member 2 and has an enlarged end 6 located near the burner front face 3. The partition wall 5 separates the interior of the hollow wall member 2 into passages 7 and 8 through which cooling fluid can circulate. The hollow wall member 2 surrounds a substantially centrally located oxygen supply passageway 9 which is arranged substantially concentrically with respect to where the solid fuel supply passageway is located. . This solid fuel supply passage 10 is separated from the oxygen supply passage 9 by a substantially cylindrical wall 11 .

In the embodiment relating to FIG. 1, the solid fuel supply passage is divided into four spaced apart solid fuel outlet passages 12 near the front of the burner, the outlet passages being spaced apart from each other. It is well located. To ensure a smooth outflow of solid fuel from the solid fuel supply passage 10 into the solid fuel outlet passage 12, the upstream portion of the solid fuel outlet passage is slightly sloped outwards. As illustrated in FIG. is mounted centrally on the Most of the solid fuel outlet passage 12 is
It is formed by a tubular element 15 firmly attached to a solid block 13. To further prevent the occurrence of stagnation areas within the solid fuel passageway, the total cross-sectional area of the solid fuel outlet passageway 12 is selected to be substantially equal to the cross-sectional area of the solid fuel supply passageway 10.

The oxygen supply passage 9 is located near the burner surface 3,
It merges into a central high velocity oxygen outlet passage 16 and via a substantially annular constricted passage 17 into a substantially annular low velocity outlet passage 18 . As clearly shown in FIG.
substantially forms a portion of a substantially annular opening in the shape of a lily tube. Low velocity oxygen outlet passage 1
The rate of expansion of 8 depends on the desired rate of oxygen exiting the passageway.

The annular low velocity oxygen outlet passageway is separated from the central high velocity oxygen outlet passageway 16 by a system of substantially concentrically arranged hollow tubular elements 19, which hollow tubular elements 19 are separated from the central high velocity oxygen outlet passageway 16 for the passage of solid fuel. It surrounds the tubular element 15.

As described above, in the first embodiment shown in FIGS. 1 and 2, the oxygen supply passage 9 and the solid fuel supply passage 10 are arranged concentrically. Furthermore, in FIGS. 1 and 2, a solid fuel supply passage 10
is shown dividing into four solid fuel outlet passages 12 via solid block 13 and tubular element 15.

Since the oxygen supplied through the passage 9 can flow freely around the solid fuel supply passage 10 due to the aforementioned concentric arrangement, it is possible for the oxygen supply passage 9 to merge into the central high-velocity oxygen outlet passage 16. It should be quite obvious. This structure is clearly shown in Figures 1 and 2 (Example 1).

Reference is now made to FIGS. 3 and 4, which illustrate another embodiment of a burner in accordance with the present invention.

It should be noted that identical parts of the two burners illustrated are designated with the same reference numerals.

In this alternative embodiment, the oxygen supply passage 9 is provided via a plurality of separate passages 20, an annular low velocity oxygen outlet passage 21 which widens in the downstream direction.
to join. As is clear from Figure 3, passage 2
0 is smaller in size than the adjacent oxygen supply passage 9 and the annular low velocity oxygen outlet passage 21;
That is, it is a narrower passage and therefore passage 2
0 corresponds to the "necked passage 17" described in FIGS. 1 and 2. The passages 20 are distributed substantially uniformly around the longitudinal burner axis 4 . The solid fuel outlet passage, indicated by the reference numeral 22, is formed in this alternative embodiment by a hole arranged in the wall of the tubular element 23.
Said passageway is formed by firstly sloping an upstream part towards the outside, an intermediate part substantially parallel to the longitudinal burner axis 4 and a downstream part by sloping towards the inside. There is. The inward slope of the downstream portion of the solid fuel outlet passage causes solid fuel to flow towards the high velocity oxygen exiting the central high velocity oxygen outlet passage 16 during operation, thereby causing the fuel and oxygen to flow together. Vigorous mixing is promoted. To closely surround the solid fuel and high velocity oxygen with a protective shield of low velocity oxygen, the annular low velocity outlet passage 21 and the ends of the solid fuel outlet passage follow substantially parallel flow paths.

The central high velocity oxygen outlet 16 is connected to a plurality of passageways 24
is fluidly connected to the oxygen supply passage through the
The passages 24 are formed within the wall of the tubular element 23 between adjacent solid fuel outlet passages 22 . It should be noted that the total cross-sectional area of the plurality of channels 24 is preferably at least equal to the cross-sectional area of the high-velocity oxygen outlet passage 16 to promote uniform high-velocity outflow of oxygen during burner operation. be.

As shown in FIGS. 1 and 3,
The constricted passageway formed by annulus 17 and passageway 20, respectively, is located downstream of the upstream end of central high velocity oxygen outlet passageway 16. The constricted passage, however, may also be placed at the upstream end of the central oxygen outlet passage to obtain a central high velocity oxygen flow and an annular low velocity oxygen flow. Although the annular low-velocity oxygen outlet passageway is shown as being formed as a ring in the drawings, it may be formed from a plurality of separate passageways, provided that it is substantially annular at least at the downstream end. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the front part of a first burner according to the invention; FIG. 2 is a front view of the burner shown in FIG. 1; FIG. 3 is a front part of a second burner according to the invention. and FIG. 4 is a cross-sectional view taken along the - line of the burner shown in FIG. 3. DESCRIPTION OF SYMBOLS 1... Burner, 2... Hollow wall member, 3... Burner front, 4... Longitudinal axis, 5... Partition wall, 6... Enlarged end, 7, 8... Passage, 9... Oxygen supply Passage, 10... Solid fuel supply passage, 11...
... cylindrical wall, 12, 22 ... solid fuel outlet passage, 13 ... solid block, 14 ... spacer element, 15, 23 ... tubular element, 16 ... high velocity oxygen outlet passage, 17 ... annular constricted passage, 1
8, 21...Low velocity oxygen outlet passage, 19...Hollow tubular element, 20, 24... Passage.

Claims (1)

[Scope of Claims] 1. Includes an oxygen supply passage and a solid fuel supply passage coaxially arranged inside the oxygen supply passage, the solid fuel supply passage having a central oxygen outlet passage and an annular oxygen outlet passage. in the burner for the gasification of finely divided solid fuel, the oxygen supply passage merging into a central high-velocity oxygen outlet passage and constricted a separate annular low velocity oxygen outlet passageway, the constricted passageway being located at or downstream of the upstream end of the central high velocity oxygen outlet passageway; A burner for gasifying solid fuel, characterized by: 2. The burner of claim 1, wherein the constricted passageway is arranged concentrically with the oxygen supply passageway. 3. The constricted passageway is formed by a plurality of uniformly spaced passageways.
Burner as described in section. 4. A burner according to claim 2, wherein the constricted passage is formed by an annular slit. 5. A burner according to any one of claims 1 to 4, wherein the annular low velocity oxygen outlet passage gradually widens in the downstream direction. 6. A burner as claimed in any one of claims 1 to 5, wherein each of the annular low velocity oxygen outlet passage and solid fuel outlet passage has a cylindrical shape. 7. A burner according to any one of claims 1 to 5, wherein the annular low velocity oxygen outlet passage and the solid fuel outlet passage each taper in a downstream direction. 8. Any one of claims 1 to 7, wherein the solid fuel outlet passage is formed by an annular conduit separating a central high velocity oxygen outlet passage from an annular low velocity oxygen outlet passage. Burner as described in one. 9. The solid fuel outlet passage is defined by a plurality of uniformly distributed conduits spaced apart on a tubular element separating a central high velocity oxygen outlet passage from an annular low velocity oxygen outlet passage. A burner according to any one of claims 1 to 7 formed therein. 10. The burner according to any one of claims 1 to 9, wherein the solid fuel supply passage is formed by a cylindrical flow passage centrally arranged inside the oxygen supply passage.