JPH0143200B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an elbow, particularly an elbow installed in the middle of a pipe that carries fine solids in a gaseous state, and which effectively reduces wear on such an elbow. It is.

An example of such an elbow is a coal nozzle inlet elbow that is installed in the middle of a pipe that supplies pulverized coal from the mill to a burner installed in a steam generator furnace. However, such an elbow suffers from severe wear as pulverized coal, particularly relatively large coal particles, collide with the inner surface of the elbow, and as a result, the plant must be frequently shut down to replace the elbow.

In order to solve these problems, conventional attempts have been made to attach a ceramic liner to the inner surface of the elbow or to make the entire elbow from a ceramic material. However, the manufacturing cost of such an elbow is high, several times the cost of a metal elbow. Moreover, ceramic liners or ceramic elbows are easily broken. Furthermore, even ceramic materials will eventually wear out.

The present invention has been made to solve these conventional problems.

According to the present invention, a mat formed by collecting metal fibers is attached to the inner surface of the outer curved portion of an elbow inserted in the middle of a pipe that carries fine solids in a gaseous state. Therefore, when a gas carrying fine solids flows through the elbow, a portion of the fine solids are thrown off by centrifugal force and captured by the metal fiber mat. These captured fine solids are then gradually packed tightly into the metal fiber mat by collision with other fine solids that are thrown away. Therefore, the lining is ultimately formed by fine solids packed into the mat. This lining forms a very effective wear surface. If a portion of the fine solids packed into the mat falls off, this portion is quickly repacked by other fine solids that are thrown away. It can therefore be said that such a wear surface is formed by the highly abrasive material itself.

A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

In FIGS. 1 to 4, reference numeral 10 is a pipe 3.
An elbow is shown for use in the pipe through which fine solids are carried in the gas flow. This pipe 30 is used, for example, to transport pulverized coal from the mill to the furnace of a steam generator, which is ground in a grinding mill and carried on an air stream.

Thus, as the gas stream carrying fine solids passes through the elbow 10, many solids, particularly heavy solid particles, are thrown outwardly and impinge on the inner surface of the outer bend 12 of the elbow. If such abrasive solids continue to impinge on the inside surface of the elbow, the elbow will eventually wear out and must be replaced, even if it is made of a durable material.

Therefore, according to the present invention, most of the outer bent portion 12 of the elbow 10 (for example, in the case of a 90° elbow,
A mat 14 formed by gathering metal fibers, for example by brazing, is attached to the inner surface of the 75° arched portion. Therefore, when fine solids, such as coal particles carried by the air flow, are blown outward so as to collide with the inner surface of the outer curved portion 12 of the elbow 10, most of them are blown away by the numerous particles of the metal fiber mat 14. Trapped in a narrow passage. The coal particles are continuously captured by the metal fiber mat until each passageway of the metal fiber mat 14 is filled with coal particles. The coal particles thus captured by the metal fiber mats are packed quite tightly due to subsequent collisions with other coal particles that are thrown around at a fairly high speed. go. If the packed coal particles flake off, other flung coal particles will be caught by the metal fiber mat in place of the flaked coal particles. Thus, a metal fiber mat exposed to a highly abrasive coal stream will eventually become a coal lining formed by a large number of packed coal particles. Some wear occurs on the metal fibers of the mat as some of the packed coal particles flake off. However, such wear is much less than the wear that occurs over an entire elbow made of metal or ceramic material. Therefore, by applying the invention, the useful life of the elbow is extended considerably.

According to this embodiment, the metal fiber mat 14
is secured to the receiving plate 16 by a plurality of studs 18 and nuts 20 associated with these studs. That is, each stud 18 has an integrally connected base or plate 22 that is welded to the metal fiber mat 14, as shown in detail in FIG. Also, each nut 20
The entire circumference of the receiving plate 16 is marked with reference numeral 24.
As shown in the figure, it is sealed and welded, making it fluid-tight. The backing plate 16 is welded around the circumference to the elbow 10, as shown at 26, thereby completing the elbow. The flanges 28 formed at both ends of the elbow 10 are connected, for example, by bolts, to flanges formed at the ends of a straight pipe 30, respectively.

In the construction described above, the mat 14 may be formed by assembling suitable metal fibers to capture fine solid particles, such as coal particles, and to form a matrix having numerous fine passages into which these coal particles may be packed. The most suitable mat is one in which metal fibers are assembled into a mat by brazing. This mat can be easily compressed to the desired density after the metal fibers have been assembled by brazing and can be formed into any configuration, such as that illustrated in FIGS. 2 and 3 for use in the present invention. It can be easily bent into any shape.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of an elbow according to the present invention interposed in the middle of a pipe, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIG. 3 is a 3--3 in FIG. 3
4 is a sectional view taken along the line 4--4 in FIG. 2. 10... Elbow, 12... Outer bent portion of elbow, 14... Metal fiber mat, 16... Receiving plate, 18... Stud, 20... Nut, 22...
... Base, 24, 26 ... Welded part, 28 ... Flange, 30 ... Pipe.

Claims (1)

[Claims] 1 An elbow inserted in the middle of a pipe that transports fine solids in a gas has an inner bent part and an outer bent part, and a mat formed by collecting metal fibers on the inner surface of this outer bent part. An elbow characterized in that the mat captures a portion of fine solids in the gas flowing through the elbow, and these captured fine solids are packed inside the mat to form a lining.