JPH0140970Y2 - - Google Patents

Description

[Detailed description of the invention] Background of the invention The invention relates to a burner nozzle chip used in a pulverized coal combustion furnace, and more specifically, to a replaceable cast or plastic insert made of a highly wear-resistant material. The present invention relates to a nozzle tip for a pulverized coal combustion burner having a replaceable end cap made of heat-resistant material.

One common method of burning coal in the furnace of a conventional coal-fired steam generating boiler is known as tangential combustion. In this method, pulverized coal is introduced into the furnace on a primary air stream that passes through a burner, often called a fuel-air intake assembly, located in a wind box in the corner of the furnace. The mixed flow of pulverized coal and air discharged from these burners is directed tangentially to an imaginary circle at the center of the furnace, creating a mass of flame in the furnace called a fireball.

Upon exiting the furnace, the combustion products produced within the fireball pass through the boiler section. The boiler section typically includes superheaters, reheaters, and various other heat absorbing surfaces to cool the combustion products and generate superheated steam. Control of the temperature of the steam leaving the superheater or reheater is effected by varying the position of the fireball formed in the furnace upon convergence of the mixed fuel and air stream leaving the burner. Tilting the burner nozzle tip at any time raises and lowers the fireball within the furnace, increasing or decreasing the heat absorption of the furnace walls, thereby increasing the temperature of the combustion products leaving the furnace and flowing through the superheater and reheater surfaces. It can be raised or lowered. As the temperature of the combustion products entering the boiler section changes, the temperature of the steam generated on a heat absorbing surface located within the boiler section changes accordingly. Such steam temperature control is shown in US Pat. No. 2,363,875.

The typical coal and air intake assembly or burner traditionally employed in tangential combustion furnaces consists of a coal discharge pipe, often referred to as a coal nozzle, through which powdered coal is discharged into the furnace in a primary air stream; an air conduit surrounding the coal discharge pipe through which additional air is discharged into the furnace, and a nozzle tip pivotally mounted on the coal discharge pipe so as to be inclined in a vertical plane, thereby The mixed flow of pulverized coal and air being discharged into the furnace through the coal discharge pipe and additional air flowing through the air conduit can be selectively directed into the furnace as required by steam temperature.

A typical prior art burner nozzle chip, such as that shown in U.S. Pat. The mixed flow of pulverized coal and air from the coal discharge pipe is fed into the furnace through a flow path formed by the inner shell, and the outer shell surrounds the inner shell at a distance and has an annular duct therebetween. The air exiting the air conduit of this annular duct is directed into the furnace. Additionally, one or more steel or stainless steel buttholes, referred to as splitter plates, are disposed within the inner shell of the nozzle tip parallel to its long axis to facilitate the mixing of coal and air exiting through the inner shell. It provides additional directional force to the flow and ensures uniform distribution of the mixed coal and air flow when the nozzle is tilted away from the horizontal for steam temperature control.

A major problem in the past when using such nozzle tips has been that steel or stainless steel splitter plates have been damaged due to the extreme erosion caused by the impingement of pulverized coal carried by the high velocity air stream from the coal discharge pipe. This means that it wears out quickly. As these splitter plates wear, they become less able to direct the mixed flow of pulverized coal and air into the furnace, reducing the effectiveness of the nozzle tips. Furthermore, when the nozzle tip is tilted from the horizontal, pulverized coal impinges on the walls of the inner shell, increasing and accelerating wear on the inner shell.

The nozzle tip is exposed to heat from the flame in the furnace. Prior nozzle tips were susceptible to cracking due to exposure to heat from the furnace flame where the splitter plate was welded to the inner shell or the inner shell was welded to the outer shell.

The burner nozzle chip disclosed in U.S. Pat. No. 3,823,875 purports to solve the aforementioned problem by forming the burner nozzle chip from an outer shell made of heat-resistant stainless steel and an inner shell made of corrosion-resistant stainless steel. Both shells are fabricated by casting or molding rather than welding, and are assembled mechanically to form the nozzle tip rather than by welding. To replace the inner shell (which, although made from corrosion-resistant stainless steel, must be replaced sooner than the outer shell), the nozzle tip must be completely removed from the coal nozzle itself, and the inner shell rearwardly removed from the outer shell. must be pulled out. A new inner shell must then be inserted into the outer shell and the entire coal nozzle tip must be reattached to the coal nozzle. This is a cumbersome and time-consuming task that must be done when the furnace is not operating, thereby unnecessarily extending the downtime of the furnace.

Therefore, the object of the present invention is to provide a highly corrosion-resistant, replaceable insert that forms a flow path for feeding powdered coal in the primary air from the coal discharge pipe into the furnace, and a nozzle tip end that is exposed to high temperatures in the furnace. An object of the present invention is to provide an improved nozzle tip for a pulverized coal combustion burner, which includes a heat-resistant replaceable end cap attached to a pulverized coal combustion burner.

Another object of the present invention is to provide an improved burner nozzle tip that can be easily removed from inside the furnace without removing the burner nozzle tip from the burner's coal discharge pipe.

Still another object of the invention is to provide a replaceable, non-welded cast or molded insert of a highly wear-resistant material that mates with the nozzle tip body and that allows the nozzle tip to be inserted by mechanical means rather than welding. To provide a replaceable end cap of a highly heat resistant material fixed to the body.

Summary of the invention The burner nozzle chip of the pulverized coal combustion furnace according to the present invention receives the flow of pulverized coal and air discharged from the coal discharge pipe of the burner and directs it into the furnace.
It consists of a base body, a wear-resistant replaceable cast or molded insert, and a heat-resistant replaceable end cap that can be easily attached to the base body by mechanical means. Facilitates disassembly of the nozzle tip to replace inserts or end caps.

A hollow, open-ended, non-welded insert of a highly wear-resistant material is located intermediate and retained between the base body and the end cap. The insert forms a highly wear-resistant flow conduit from the discharge end of the base body through the nozzle tip to the receiving end of the end cap through which the pulverized coal and air flow from the burner to the furnace.

The base body is attached to the coal discharge port of the coal discharge pipe by mechanical means. In a preferred embodiment, the base body includes a hollow, open-ended outer shell pivotally mounted at the discharge end of the burner and a hollow, open-ended outer shell spaced coaxially within the outer shell. a first flow passage passing through the inside of the inner shell and a second flow passage passing through an annular space between the inner shell and the outer shell.
It forms a flow path.

The wear-resistant insert lining the coal nozzle tip consists of a hollow, open-ended, unwelded shell casting or molding of wear-resistant material in the form of a rectangular frustum with a tapered channel. It is preferable that it is formed. At least one integrally cast or molded, non-welded splitter plate is placed within the flow path of the insert to further divide the flow path and direct the flow of powdered coal and primary air through the multiple flow paths to the furnace. It is preferable to send it to

The replaceable end cap has a hollow, open-ended outer shell and a hollow, open-ended inner shell spaced and coaxially disposed within the outer shell, and includes a first flow path through the inner shell. form,
A second flow path is then formed through the annular space between the inner shell and the outer shell. A plurality of plate-like members disposed transversely between the inner and outer shells extend from the shells to engage and be secured to the base body of the coal nozzle tip. Preferably, the replaceable end cap is formed from high temperature stainless steel.

A replaceable end cap is removably attached to the base body of the nozzle tip, a wear-resistant insert is secured between the end cap and the base body, and the inlet end of the inner shell of the end cap is connected to the outlet of the wear-resistant insert. and the outlet end of the inner shell of the base body with the inlet end of the wear-resistant insert.
A first flow path is formed through the inner shell of the vane body, through the interior of the open ended insert, and through the inner shell of the end cap. Additionally, the inlet end of the outer shell of the replaceable end cap mates with the outlet end of the outer shell of the base body, such that there is a connection between the inner and outer shells of the base body and the inner shell and outer shell of the replaceable end cap. A second flow path is formed through the annular space between the two. The pulverized coal and primary air being supplied to the furnace from the burner outlet flow through the first passage, and the second air being supplied to the furnace flows through the second passage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The accompanying drawings show a nozzle tip 10 improved in accordance with the present invention. As shown in FIG. 1, the burner nozzle tip 10 includes a base body 20, a replaceable abrasion resistant insert 30, and a replaceable end cap 40.
In FIG. 1, the burner nozzle tip 10 is shown disassembled with the components aligned for assembly. In Figures 2 and 3, burner nozzle tip 1
0 is attached to a fuel and air intake assembly of the type typically used in pulverized coal furnaces employing tangential combustion, ie, to the coal discharge pipe of the burner. However, the nozzle tip 10 of the present invention may be readily incorporated into other types of burners without departing from the spirit and scope of the present invention.

The nozzle tip 10 of the present invention has three components: a base body 20, a replaceable wear-resistant insert 30, and a replaceable end cap 4.
0 and these are wear-resistant inserts 30
Alternatively, it is assembled so that it can be easily removed when disassembling the end cap 40 for replacement. The hollow, open-ended base body 20 is adapted to be mounted, preferably pivotably, to the discharge end of the coal discharge pipe 50. A replaceable open-ended end cap 40 can be easily removed from the ejection end of the base body 20 by, for example, but not limited to, bolts, pins, tack welds, and other well-known methods. Install using the same technology.

A replaceable, hollow, open-ended, weldless insert 30 of a highly wear-resistant material is located intermediate the base body 20 and the end cap 40 and is secured to the base body 20. It is held between the base body and the end cap by an end cap 40. The insert forms a highly wear resistant flow conduit through the nozzle tip from the outlet end of the base body 20 to the inlet end of the end cap 40. The mixed flow of powdered coal and air flows from the coal discharge pipe 50 to the base body 2.
0 through, then wear-resistant insert 30
and flows into the furnace through end cap 40.

Functionally, the burner nozzle tip 10 provides a means for imparting a directional force to the pulverized coal exiting the coal discharge pipe 50 and to the air being directed from the wind box 60 to the furnace. The base body 20 fits around the discharge end of the coal discharge pipe 50 and is pivotally attached thereto. The nozzle 10 is a coal discharge pipe 50
can be tilted about an axis perpendicular to the long axis of the furnace, thereby changing the position of the fireball in the furnace and achieving temperature control of the steam. In its normal position, the nozzle tip 10 is arranged with its long axis aligned with the long axis of the coal discharge pipe. Coal discharge pipes are generally arranged horizontally. To raise the fireball in the furnace, the nozzle tip 10 is rotated about the pivot pin 52 and tilted upward, thereby directing both the pulverized coal and air flow and the secondary air flow upward. . Similarly, if the fireball is to be lowered in the furnace, the nozzle tip 10 is rotated about the pivot pin 52 and tilted downward, thereby reducing the flow of pulverized coal and air.
Make sure that both the airflow and the airflow are directed downwards.

In practice, it is necessary that the discharge end of the nozzle tip 10 extends slightly into the furnace. Therefore, the discharge end of the nozzle tip 10 is exposed to high temperatures within the furnace and heat transfer from the flame. Furthermore, a coal discharge pipe 50
The pulverized coal in the mixed flow of primary air and pulverized coal exiting from and passing through the nozzle tip 10 is highly abrasive;
In particular, when the nozzle tip 10 is tilted away from the long axis of the coal pipe 50, the inner surface of the nozzle tip 10 is severely eroded due to the collision of powdered coal against the inner surface of the nozzle tip 10.

The improved nozzle tip 10 of the present invention includes a replaceable heat resistant end cap 40 and a replaceable wear resistant insert for lining the inside of the nozzle tip 10. This replaceable end cap 40 is preferably formed from high temperature resistant stainless steel, which increases the life of the end cap 40 in the furnace atmosphere, and at the same time protects the other parts of the nozzle tip, particularly the cast or molded insert 30. The wear-resistant insert 30, which protects the steel from the heat generated in the furnace, is made of a highly wear-resistant material, preferably nickel hard.
-Hard) monolithic casting or molding. However, silicon carbide or highly wear-resistant stainless steel may also be used. A wear-resistant insert 30 protects the end cap 40 from impingement by pulverized coal in the mixed flow of pulverized coal and primary air exiting the coal discharge pipe 50 and passing through the nozzle tip 10.

Insert 3 that is wear resistant from the heat generated in the furnace
0 and from erosion caused by the pulverized coal in the mixed flow of pulverized coal and air exiting through the nozzle tip 10.
The life of the nozzle tip in the furnace atmosphere can be greatly extended by providing a wear-resistant insert 30 to protect the nozzle tip.

This is because the selection of materials for forming the heat-resistant end cap 40 and insert 30 can be optimized. That is, the material selected to form the end cap 40 can be selected with only heat resistance in mind, without considering wear resistance, and the material selected to form the wear resistant insert 30 can be selected with heat resistance in mind. You can make a selection based only on wear resistance, without considering performance.

1, 2 and 3, the hollow, open-ended base body 20 of the nozzle tip 10 has an outer shell 22 and is spaced therefrom within the outer shell 22. an inner shell 24 arranged coaxially, and a first flow path passing through a hollow internal space of the inner shell 24;
a second flow path passing through the annular space between the inner shell and the outer shell. Preferably, a plurality of plate-like support ribs 26 are disposed transversely between the inner and outer shells of the base body to increase the structural integrity of the base body.

As best shown in FIG. 3, the base body 20 is attached to the discharge end of a coal discharge pipe 50 of a pulverized coal burner. Coal discharge pipe 50
It is preferable that the base body 20 is rotatably attached to the discharge end of the base body 20 by a rotary pin or the like. The pulverized coal and the primary air stream emerging from the coal discharge pipe 50 pass through the hollow interior of the inner shell 24 of the base body 20 and into the wear-resistant insert 30, while the secondary air stream emerging from the wind box 60 flows into the wear-resistant insert 30. Air flows through the annular space between the inner and outer shells of the base body 20.

A replaceable, hollow, open-ended end cap 40 has an outer shell 42 and an inner shell 44 spaced apart and coaxially disposed within the outer shell 42.
forming a first flow path through the hollow interior of the inner shell 44 and a second flow path through the annular space between the inner and outer shells of the end cap 40 being replaced. To increase the structural integrity of the end cap 40, a plurality of plate-like support ribs 46 are preferably disposed transversely between the inner and outer shells of the end cap. Furthermore,
At least one splitter plate 54 is connected to the end cap 4 parallel to the long axis of the coal discharge pipe 50.
0 in the inner shell 44 to subdivide the inner shell into multiple passageways.

As previously mentioned, it is preferable to construct the replaceable end cap 40 from stainless steel, which is particularly heat resistant. The replaceable end cap 40 is removably attached to the base body 20 and secures a wear resistant insert 30 therebetween. Replaceable end cap 4
0 to the base body 20 such that the outer shell 42 of the end cap 40 mates with the outer shell 22 of the base body 20 to thereby form a secondary air flow conduit through which the The combustion air then passes from the windbox 60 through an annular passage between the inner and outer shells of the base body 20 and through an annular passage between the inner and outer shells to the exchangeable end cap 40 and into the furnace. flows to

In a preferred embodiment, the means for removably attaching end cap 40 to base body 20 is disposed transversely between inner shell 24 and outer shell 22 of base body 20 and extends toward end cap 40. A second plate member disposed across the plurality of plate-like members 28 and the inner shell 44 and outer shell 42 of the end cap 20 and extending in the direction toward the base body 20.
A plurality of plate-like members 48 are provided. Hole 2
9 in the plate-like member 28 and a hole 49 in the plate-like member 48 to form a replaceable end cap 4.
0 into the base body 20, the hole 29 of the plate-like member 28 of the base body 20 and the hole 49 of the plate-like member 48 of the end cap 40 are made to match. As best shown in FIG. 2, removable fastening means 62, such as but not limited to pins or bolts, are threaded through the first plate-like member 28 and the second plate-like member 48 to the base body. An end cap 40 is removably attached to the end cap 20.

As already mentioned, a replaceable, hollow, open-ended, weld-free insert 30 of a highly wear-resistant material is placed intermediate the base body 20 and the end cap 40 when assembling the nozzle. . The inlet end 32 of the insert 30 mates with the outlet end of the inner shell 24 of the base body 20, and the outlet end 34 thereof mates with the inlet end of the inner shell 42 of the end cap 40 being replaced. to form a flow conduit,
Pulverized coal and primary air exiting the coal discharge pipe 50 pass through this conduit and enter the insert 30 inside the inner shell 22 of the base body 20 and into the inner shell 4 of the end cap 40.
Enter the furnace through the inside of 2.

The insert 30 enters completely within the nozzle 10;
Since the end cap 40 is protected from exposure by the heat generated by the flame in the furnace, the insert 3 is made of a material selected only for its wear resistance properties without considering its heat resistance properties.
0 can be created. Preferably, the wear resistant insert 30 is cast from a highly wear resistant material such as hard nickel hard, silicon carbide or stainless steel.

The wear-resistant insert 30 is hollow and open ended in the form of a truncated pyramid. Consisting of a shell without welds, the inlet end 3 of the insert 30
Preferably, the flow path is tapered inwardly from 2 to the outlet end 34. Additionally, at least one monolithically cast or molded, non-welded splitter plate 36 is disposed within the convergent passageway substantially parallel to the longitudinal axis of the coal discharge pipe 50 and re-enters the convergent passageway of the insert 30. To divide. More preferably, the insert 30 is cast in one piece or molded.
An inner splitter plate 36 extends outwardly through the inlet end 32 of the frustum-shaped shell. The outlet edge 34 of the wear-resistant insert 30 abuts the inner shell 42 of the replaceable end cap 40 and the inlet edge 3 of the insert
A wear-resistant insert 30 is disposed within the nozzle tip 10 with the insert 2 abutting the inner shell 24 of the base body 20. Thus, even if the nozzle tip 10 is tilted downward, the wear-resistant insert 30 remains
is prevented from falling into the furnace by the end cap 40 being replaced, and similarly, the wear-resistant insert 30 is prevented from falling into the coal discharge pipe 50 by the base body 20 even if the nozzle tip 10 is tilted upwards. has been done. More preferably, the replaceable end cap 40
Support rib 46 between the inner shell and the outer shell
and plate-like member 48 are machined along their inner surfaces to engage the sides of a wear-resistant insert 30 disposed intermediate the end cap 40 and the base body 20 to provide a wear-resistance during operation. This is to ensure that the sexual insert 30 is fixed in the correct position.

The improved nozzle tip 10 for a burner burning pulverized coal is expected to have a longer service life than conventional nozzle tips in the high temperatures and extremely corrosive atmospheres associated with pulverized coal combustion. . The cast or molded insert 30 forming the tapered portion of the pulverized coal flow path through the nozzle tip 10 is made from a highly wear resistant material. It resists the impact of coal particles flowing through the nozzle tip better and has a much longer life in aggressive atmospheres.

Furthermore, since the highly heat resistant end cap 40 protects the insert 30 from the harmful furnace atmosphere, proper material selection for the insert 30 and the use of highly wear resistant materials will extend the useful life of the nozzle tip. Extend it further. Furthermore, nozzle tip 1
Since the cast or plastic insert 30 protects the highly heat resistant end cap 40 from impact by coal grains flowing through the end cap 40, proper selection of the material for the end cap 40 being replaced will allow the end cap 40 to be replaced. Nozzle tip 10 using highly heat resistant material to form
The useful life of the product can be extended again.

Furthermore, since the end cap 40, which can be replaced with a cast or molded insert 30, is removably attached to the base body 20, and because only the base body 20 is attached to the coal discharge pipe 50, the nozzle tip 10 can be easily installed. an end cap 4 that can be accessed from inside the furnace and thus replaced with a cast or molded insert 30;
0 can be removed and replaced at very short notice during normal furnace shutdown when necessary.

Although the preferred embodiment of the present invention has been illustrated and described in the best mode presently contemplated as incorporated into a fuel-air discharge assembly of the type typically used in tangential combustion furnaces, the present invention It is not limited to the examples. The nozzle tip of the present invention can be modified by a person skilled in the art within the scope of the technical idea of the present invention so that it can be applied to any burner that burns pulverized coal or other abrasive solid fuels. be.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an improved nozzle chip according to the present invention, with the components of the nozzle chip shown disassembled but aligned for assembly. 2-2 of FIG. 3 shows the nozzle tip of the present invention assembled and installed in a typical fuel-air intake assembly used in a pulverized coal combustion furnace with tangential combustion. FIG. FIG. 3 shows a nozzle tip according to the present invention installed in a typical fuel-air intake assembly employed in a tangential combustion type pulverized coal combustion furnace.
FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2; DESCRIPTION OF SYMBOLS 10... Burner nozzle chip, 20... Base body, 22... Outer shell, 24... Inner shell, 28... Plate member, 29... Hole, 30...
...insert, 40...end cap, 42...
...outer shell, 44...inner shell, 46...support rib, 48...plate member, 49...hole, 5
0... Coal discharge pipe, 52... Rotating pin, 54
...Splitsa plate, 60...Wind box.

Claims (1)

[Claims for Utility Model Registration] 1. In a nozzle tip that receives a flow of pulverized fuel and air from a burner of a furnace that burns pulverized fuel, and directs the flow of pulverized fuel and air toward the furnace, (a ) is adapted to be pivotally mounted to the discharge end of the burner and has an outer shell and an inner shell spaced apart and substantially coaxially disposed within the outer shell, with a first
(b) a hollow, open-ended base body adapted to define a flow path through the annular space between the inner shell and the outer shell; an inner shell spaced apart and substantially coaxially disposed to define a first flow passage within the inner shell and a second flow passage through an annular space between the inner shell and the outer shell; a replaceable, hollow, removably attached to the base body at the discharge end of the base body;
an end cap that is open ended; and (c) is made of a highly wear-resistant material intermediate the base body and the end cap and is retained therebetween by the base body and the end cap; an end abutting the discharge end of the inner shell of said base body and an outlet end abutting the receiving end of the inner shell of said end cap, from the discharge end of the first channel of the base body to the first end of the end cap.
A replaceable, hollow-ended conduit passes through the nozzle tip to the receiving end of the flow path to form a highly wear-resistant conduit through which the pulverized fuel and air flow flows from the burner into the furnace. Nozzle tip with open insert; 2. said replaceable hollow, open-ended insert tapering inwardly from a receiving end adjacent said base body to a discharge end adjacent said end cap, thereby A nozzle tip according to claim 1 forming an inwardly tapered flow conduit through the nozzle tip from a discharge end of said end cap to a receiving end of said end cap. 3. Said means for removably attaching said end cap to said base body: (a) disposed transversely between an inner shell and an outer shell of said base body; It extends in the direction of
(b) a first plurality of plate-like members having through holes; (b) disposed transversely between an inner shell and an outer shell of the end cap and extending in a direction toward the base body;
(c) a second plurality of plate-like members having through holes arranged to align with holes in the first member when the end cap is fitted to the base body; 2. A nozzle tip according to claim 1, further comprising removable fastening means disposed through matching holes in said first member and said second member for attachment to said base body. 4. Each of a second plurality of plate-like members disposed transversely between the inner shell and the outer shell of the end cap and extending in a direction toward the base body connects the end cap and the base body. 4. The nozzle tip according to claim 3, which engages with a side surface of the insert located intermediate between the nozzle tip and the insert. 5. The nozzle tip according to claim 4, wherein said base body is made of wear-resistant stainless steel, and said replaceable end cap is made of heat-resistant stainless steel. 6. The nozzle tip of claim 5, wherein said replaceable, hollow, open-ended insert is formed as a single piece of nickel hard material.