Dispensing – Weighing
Reexamination Certificate
2001-10-18
2003-02-25
Kaufman, Joseph A. (Department: 3754)
Dispensing
Weighing
C222S129000, C222S152000, C222S415000
Reexamination Certificate
active
06523721
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a granular material supply system for a closed system and, more particularly, to a granular material supply system including a pressure case, a conveying means disposed in the pressure case, and a weighing means for weighing the granular powder being conveyed by the conveying means when necessary, and combined with a delivery unit for delivering granular powder supplied thereto by a granular powder supply unit.
BACKGROUND ART
Various plants including smelting reduction steelmaking plants, direct reduction steelmaking plants, coal gasification plants and vacuum degassing plants produce a poisonous gas or an inflammable gas or supplies a poisonous gas or an inflammable gas into a reaction furnace. Such a plant uses a granular material supply system capable of supplying a granular material into the reaction furnaces without opening the plant into the environment.
The inventors of the present invention proposed a granular material supply system
100
to be applied to a smelting reduction steelmaking plant. As shown in
FIG. 8
, this previously proposed granular material supply system
100
includes, as principal components, a granular material loading unit
101
, a granular material supply hopper
102
, a vibrating feeder
103
, load cells
104
for weighing the granular material supply hopper
102
containing a granular material, and a chute
105
. The granular material, such as granular powder iron ore or coal, is loaded through the granular material loading unit
101
into the granular material supply hopper
102
, the granular material supply hopper
102
containing the granular material is weighed, the vibrating feeder
103
carries the granular material to the chute
105
, and then the granular material is supplied through the chute
105
into a processing unit, such as a furnace.
In the granular material supply system
100
, a loading line
110
provided with a stop valve
111
and a metal expansion joint
112
connects the granular material loading unit
101
and the granular material supply hopper
102
, a discharge line
113
provided with a rubber expansion joint
114
connects the granular material supply hopper
102
and the vibrating feeder
103
, and a feed line
115
provided with a rubber expansion joint
116
and a stop valve
117
connects the vibrating feeder
103
and the chute
105
.
The load cells
104
weigh the sum of the weight of the granular material supply hopper
102
and that of the granular material contained in the granular material supply hopper
102
. Therefore the metal expansion joint
112
is indispensable and the load cells
104
need to support the granular material supply hopper
102
. The vibrating feeder
103
has one end part held through the rubber expansion joint
114
by the granular material supply hopper
102
. The rubber expansion joints
114
and
116
absorb vibrations of the vibrating feeder
103
. A gas line
121
provided with an equalizing valve
120
has one end connected to the granular material supply hopper
102
and the other end connected to the vibrating feeder
103
. When weighing the granular material supply hopper
102
and the granular material contained in the granular material supply hopper
102
, the respective pressures in the granular material supply hopper
102
and the vibrating feeder
103
are equalized to prevent the reduction of weighing accuracy.
When supplying a granular material from a granular material supply hopper
130
through chutes
133
and
134
to two granular material receiving units
131
and
132
at a fixed distance of, for example, about 40 m, the chutes
133
and
134
must be inclined at a fixed inclination to a horizontal plane of, for example about 50° to enable the granular material to fall smoothly through the chutes
133
and
134
. Consequently, the granular material supply hopper
130
must be installed on a level at several tens meters, for example, about 50 m, above the ground.
In a granular material weighing and conveying system disclosed in JP-U No. Hei 7-34023, a weighing tank is supported on a load cell, a base placed on a fixed body is supported on a bellows under the weighing tank, the bellows and the weighing tank are connected by a pressure line and the pressure in the weighing tank is regulated by an equalizing valve to weigh the granular material by the load cell so that weighing accuracy may not be reduced.
A fixed-quantity granular material feed method disclosed in JP-A No. Sho 54-129684 weighs a granular material while the same is being conveyed from a plurality of granular material storage tanks by belt conveyors. This method is not intended for feeding a granular material to a pressure unit without opening a closed system to the external environment.
The aforesaid granular material supply system
100
needs the metal expansion joint to weight the granular material supply hopper
102
containing the granular material, needs the rubber expansion joints
114
and
116
to absorb the vibrations of the vibrating feeder
103
and needs the gas line
121
provided with the equalizing valve
120
to prevent the reduction of weighing accuracy. Consequently, the granular material supply system
100
is complicated in construction, is large and requires large equipment investment.
Measurement of the sum of the weight of the granular material supply hopper
102
and that of the granular material contained in the granular material supply hopper
102
reduces weighing accuracy. Particularly, weighing error is very large when the capacity of the granular material supply hopper
102
large. For example, if the capacity of the granular material supply hopper
102
is 500 tons and weighing accuracy is 0.5%, weighing error is as large as 2.5 tons. The vibrations of the vibrating feeder
103
reduce weighing accuracy.
The rubber expansion joints
114
and
116
must be capable of withstanding vibrations exerted thereon by the vibrating feeder
103
to prevent the leakage of gases from the granular material supply system. However, it is impossible to prevent the leakage of gases through the rubber expansion joints
114
and
116
perfectly. The use of rubber expansion joints
114
and
116
deficient in durability causes serious problems particularly when the gases are inflammable or poisonous.
When supplying a granular material from the single granular material supply hopper
130
to the two furnaces
131
and
132
as shown in
FIG. 9
, the granular material supply hopper
130
must be installed on a high level and the chutes
133
and
134
connecting the granular material supply hopper
130
to the two furnaces
131
and
132
are very long. Consequently, this granular material supply system including the chutes
133
and
134
needs a large space for installation and a very large equipment investment.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to simplify the construction of a granular material supply system for a closed system, to enhance the weighing accuracy of the granular material supply system, to enhance the airtightness of the granular material supply system, to reduce the size of the granular material supply system and space for installation and to enhance the economical advantage of the granular material supply system.
According to a first aspect of the present invention, a granular material supply system for supplying a granular material to a granular material using apparatus included in a closed system without opening the closed system to the external environment comprises a granular material supply unit holding a granular material, and a granular material feed unit that receives the granular material from the granular material supply unit and feeds the same, wherein the granular material feed unit includes a pressure case provided with an inlet connected to the granular material supply unit and an outlet for feeding the granular material, and a conveying means disposed in the pressure case to convey the granular material received through the inlet to the outlet.
The conveying means may be a
Kishimoto Mitsuharu
Murata Kenichiro
Nomoto Hiroki
Kaufman Joseph A.
Kawasaki Jukogyo Kabushiki Kaisha
Oliff & Berridg,e PLC
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