The present disclosure relates to a mill roller, a mill table, a solid fuel
pulverizer, and a method of manufacturing the mill roller.
Background Art
[0002]
10 In the prior art, a solid fuel such as biomass fuel or coal is pulverized
into a fine powder form within a predetermined particle size range by a
pulverizer (mill) and supplied to a combustion device. In a mill, a solid fuel
charged into a mill table is pulverized by being sandwiched between the mill
table and a mill roller, and among the pulverized solid fuel in a fine powder
15 form, a fine powder fuel within a predetermined particle size range is selected
by a classifier, and carried into a boiler by a carrier gas (primary air) supplied
from an outer periphery of the mill table and combusted by a combustion
device. In a thermal power plant, steam is generated through heat exchange
with combustion gas generated by the combustion of the fine powder fuel in the
20 boiler, and a steam turbine is rotationally driven by the steam thus rotationally
driving a generator connected to the steam turbine, so that power is generated.
[0003]
Among the solid fuels, some biomass fuels, such as wood chips, have a
property of being difficult to be finely pulverized, but have a property of being
25 highly combustible and capable of being suitably combusted even when having
a relatively large particle size.
When such a biomass fuel is used as a solid fuel in a boiler, the biomass
fuel is pulverized by a mill to a particle size of about five to ten times larger
than that of a coal, and supplied to a combustion device provided in the boiler.
30 As described above, since the coal and the biomass fuel have different
particle sizes to be supplied to the combustion device, it is intrinsically
preferable that a mill for pulverizing and classifying a solid fuel is separately
designed (e.g., the housing shape, the rotational speed of the mill table, the
rotational speed of the classifier, etc.) for biomass fuel pulverizing use and coal
35 pulverizing use. However, from the viewpoint of equipment cost, installation
space, and the like, it is desired that both solid fuels of biomass fuel and coal
can be handled with the same mill, and the biomass fuel can be used by using a
mill that can share the coal and the biomass fuel.
2
[0004]
As a mill roller provided in a mill, a ceramic-embedded mill roller or a
mill table in which a ceramic having high abrasion resistance is embedded in a
portion that comes into contact with a solid fuel is known (e.g., Patent
5 Document 1). Such a ceramic-embedded mill roller and a mill table are
excellent in abrasion resistance and allowable abrasion amount as compared
with a known mill roller and a mill table, and can achieve a longer life.
Patent Document 1 describes a pulverizing member including a
supporting body made of high Cr steel in which a supporting wall is
10 continuously formed while forming a polygonal space, and a ceramic member
disposed in the space of the supporting body made of high Cr steel.
A mill roller accommodated inside a housing and configured to pulverize
5 a solid fuel with the solid fuel sandwiched between the mill roller and a mill
table that rotates and co-rotate about a rotation axis upon receiving a rotational
force from the mill table, the mill roller comprising:
a supporting portion rotatably supported with respect to the housing; and
a roller part having an annular shape, fixed to the supporting portion,
10 and configured to pulverize the solid fuel between the roller part and the mill
table, wherein
the roller part includes a base part fixed to the supporting portion, and a
ceramic part provided on an outer peripheral portion of the base part and
having superior abrasion resistance to the base part, and
15 the ceramic part includes first ceramic particles including an acuteangled corner part.
[Claim 2]
The mill roller according to claim 1, wherein
20 the ceramic part includes second ceramic particles whose main outside
surface is curved and whose abrasion resistance is superior to abrasion
resistance of the first ceramic particles, and
in the ceramic part, a mixing ratio of the first ceramic particles and the
second ceramic particles changes along a direction of the rotation axis.
25
[Claim 3]
The mill roller according to claim 2, wherein
in the ceramic part, a mixing ratio of the second ceramic particles in a
first region including a maximum abrasion point, which is a point where
30 abrasion is most likely to occur on an outside surface of the roller part, is
higher than a mixing ratio of the second ceramic particles in a second region
located closer to an end portion side in the direction of the rotation axis than
the first region.
35 [Claim 4]
The mill roller according to claim 2, wherein
in the ceramic part, the second ceramic particles are disposed along a
contact surface in contact with the outer peripheral portion of the base part, and
39
the first ceramic particles are disposed closer to an outside surface side
of the roller part than the second ceramic particles.
[Claim 5]
5 A mill table accommodated inside a housing and configured to be
rotated about a center axis by a driving force transmitted from a drive unit and
pulverize a solid fuel with the solid fuel sandwiched between the mill table and
a mill roller, the mill table comprising:
a table portion to which the solid fuel is supplied, wherein
10 the table portion includes a base part and a ceramic part provided on an
upper surface of the base part and having superior abrasion resistance to the
base part, and
the ceramic part includes first ceramic particles including an acuteangled corner part.
15
[Claim 6]
The mill table according to claim 5, wherein
the ceramic part includes second ceramic particles whose main outside
surface is curved and whose abrasion resistance is superior to abrasion
20 resistance of the first ceramic particles, and
in the ceramic part, a mixing ratio of the first ceramic particles and the
second ceramic particles changes along a radial direction with reference to the
center axis.
25 [Claim 7]
The mill table according to claim 6, wherein
in the ceramic part, a mixing ratio of the second ceramic particles in a
first region including a maximum abrasion point, which is a point where
abrasion is most likely to occur on an upper surface of the table portion, is
30 higher than a mixing ratio of the second ceramic particles in a second region
located closer to an end portion side in a direction of a rotation axis than the
first region, in the radial direction.
[Claim 8]
35 A solid fuel pulverizer comprising the mill roller according to claim 1
and/or the mill table according to claim 5.
[Claim 9]
40
A method of manufacturing a mill roller accommodated inside a housing
and configured to pulverize a solid fuel with the solid fuel sandwiched between
the mill roller and a mill table that rotates, and co-rotate about a rotation axis
upon receiving a rotational force from the mill table,
5 the mill roller including:
a supporting portion rotatably supported with respect to the housing, and
a roller part having an annular shape, fixed to the supporting portion,
and configured to pulverize the solid fuel between the roller part and the mill
table,
10 the roller part including a base part fixed to the supporting portion, and a
ceramic part provided on an outer peripheral portion of the base part and
having superior abrasion resistance to the base part, and
the ceramic part including first ceramic particles including an acuteangled corner part, the method comprising:
15 manufacturing the first ceramic particles including the acute-angled
corner part by pulverizing a ceramic material.
[Claim 10]
The method of manufacturing the mill roller, according to claim 9,
20 further comprising:
integrally molding the base part and the ceramic part by casting; and
scraping an outside surface of the roller part in which the base part and
the ceramic part are integrated.