U.S. patent application number 14/382157 was filed with the patent office on 2015-01-22 for powder supply device and powder supply method.
The applicant listed for this patent is DIAMOND ENGINEERING CO., LTD.. Invention is credited to Fumihito Kasagi, Kimihiro Shimono, Takahiro Takeda, Kazutoshi Teraoka.
Application Number | 20150021358 14/382157 |
Document ID | / |
Family ID | 49160812 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150021358 |
Kind Code |
A1 |
Shimono; Kimihiro ; et
al. |
January 22, 2015 |
POWDER SUPPLY DEVICE AND POWDER SUPPLY METHOD
Abstract
In a rapid load reduction mode for reducing a flow rate of
powder to be supplied to the outside of a feed tank to a
predetermined rate after a predetermined period of time, a
controller sets an internal pressure control valve to an exhaust
state and closes a powder discharge valve to a predetermined
aperture, and as soon as the powder flow rate becomes smaller than
a scheduled powder flow rate that is expected before elapse of the
predetermined period of time, the controller controls at least one
of the internal pressure control valve and the powder discharge
valve so that the powder flow rate becomes the scheduled powder
flow rate.
Inventors: |
Shimono; Kimihiro; (Toyama,
JP) ; Takeda; Takahiro; (Toyama, JP) ;
Teraoka; Kazutoshi; (Toyama, JP) ; Kasagi;
Fumihito; (Toyama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIAMOND ENGINEERING CO., LTD. |
Toyama |
|
JP |
|
|
Family ID: |
49160812 |
Appl. No.: |
14/382157 |
Filed: |
February 12, 2013 |
PCT Filed: |
February 12, 2013 |
PCT NO: |
PCT/JP2013/053250 |
371 Date: |
August 29, 2014 |
Current U.S.
Class: |
222/55 |
Current CPC
Class: |
F23K 2203/006 20130101;
F23K 2203/103 20130101; F23K 3/02 20130101; F23K 3/00 20130101;
F23K 2203/104 20130101; F23K 2203/201 20130101 |
Class at
Publication: |
222/55 |
International
Class: |
F23K 3/00 20060101
F23K003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2012 |
JP |
2012-056870 |
Claims
1. A powder supply device that supplies powder in a feed tank to
the outside of the feed tank through a powder delivery pipe
connected to the feed tank, the device comprising: an internal
pressure control valve that is connected to the feed tank and that
adjusts pressure in the feed tank; a powder discharge valve that is
connected to the powder delivery pipe; and a controller that
controls the internal pressure control valve and the powder
discharge valve, wherein: in a rapid load reduction mode for
reducing a flow rate of powder to be supplied to the outside of the
feed tank to a predetermined rate after a predetermined period of
time, the controller sets the internal pressure control valve to an
exhaust state of reducing the pressure in the feed tank and closes
the powder discharge valve to a predetermined aperture so that the
powder flow rate becomes smaller than the predetermined rate after
the predetermined period of time; and as soon as the powder flow
rate becomes smaller than a scheduled powder flow rate that is
expected before elapse of the predetermined period of time for
reducing the powder flow rate to the predetermined rate after the
predetermined period of time, the controller controls at least one
of the internal pressure control valve and the powder discharge
valve on the basis of information of the powder flow rate so that
the powder flow rate becomes the scheduled powder flow rate.
2. The powder supply device according to claim 1, wherein the
scheduled powder flow rate is determined based on the powder flow
rate that is just before the rapid load reduction mode is set.
3. The powder supply device according to claim 1, wherein: the
powder delivery pipe has a powder flowmeter connected thereto; and
as soon as the powder flow rate becomes smaller than the scheduled
powder flow rate, the controller controls the internal pressure
control valve and the powder discharge valve on the basis of
information from the powder flowmeter.
4. The powder supply device according to claim 1, wherein the
controller sets the internal pressure control valve to the exhaust
state before the powder discharge valve is closed to the
predetermined aperture.
5. A powder supply method for supplying powder in a feed tank to
the outside of the feed tank through a powder delivery pipe
connected to the feed tank, the method comprising: in a rapid load
reduction mode for reducing a flow rate of powder to be supplied to
the outside of the feed tank to a predetermined rate after a
predetermined period of time, setting an internal pressure control
valve connected to the feed tank to an exhaust state of reducing
pressure in the feed tank and closing a powder discharge valve
connected to the powder delivery pipe to a predetermined aperture
so that the powder flow rate becomes smaller than the predetermined
rate after the predetermined period of time; and as soon as the
powder flow rate becomes smaller than a scheduled powder flow rate
that is expected before elapse of the predetermined period of time
for reducing the powder flow rate to the predetermined rate after
the predetermined period of time, adjusting at least one of the
internal pressure control valve and the powder discharge valve on
the basis of information of the powder flow rate so that the powder
flow rate becomes the scheduled powder flow rate.
6. The powder supply method according to claim 5, wherein the
scheduled powder flow rate is determined based on the powder flow
rate that is just before the rapid load reduction mode is set.
7. The powder supply method according to claim 5, wherein as soon
as the powder flow rate becomes smaller than the scheduled powder
flow rate, the internal pressure control valve and the powder
discharge valve are adjusted based on information from a powder
flowmeter connected to the powder delivery pipe.
8. The powder supply method according to claim 5, wherein the
internal pressure control valve is set to the exhaust state before
the powder discharge valve is closed to the predetermined aperture.
Description
TECHNICAL FIELD
[0001] The present invention relates to a powder supply device and
a powder supply method, which can suppress the undershooting of the
powder flow rate while reducing the powder flow rate rapidly.
BACKGROUND ART
[0002] Combustion furnaces for burning pulverized fuel such as
pulverized coal supplied from powder supply devices are known as
combustion furnaces used in blast furnace facilities, thermal power
plants, and the like. In such combustion furnaces, the pulverized
fuel is burned while the pulverized fuel is jet into the combustion
furnace together with air. A method of combustion with the use of
the pulverized coal as the pulverized fuel has been widely popular
because, for example, the coal itself has high combustibility.
[0003] A gas-carried powder supply device that conveys pulverized
fuel with carrier gas is known as a powder supply device for
supplying pulverized fuel to a combustion furnace. In this powder
supply device, the pulverized fuel in a feed tank is supplied to a
powder delivery pipe and is conveyed with carrier gas in the powder
delivery pipe. The amount of pulverized fuel (powder flow rate) to
be supplied per unit time to the inside of powder delivery pipe may
be controlled by, for example, the aperture of a powder discharge
valve provided for an outlet at a bottom portion of the feed tank
or the differential pressure between the pressure in the feed tank
and the pressure in the powder delivery pipe (see Patent Document 1
below). The aperture of the powder discharge valve and the
differential pressure between the pressure in the feed tank and the
pressure in the powder delivery pipe are generally controlled by
the feedback of the information on the powder flow rate that is
detected by a powder flowmeter provided for the powder delivery
pipe or the like.
[0004] In general, the powder flow rate is determined based on the
instruction from, for example, the combustion furnace to which the
powder is supplied. When the powder flow rate is reduced, the
information on the powder flow rate is also fed back to the control
for the aperture of the powder discharge valve or the control for
the differential pressure between the pressure in the feed tank and
the pressure in the powder delivery pipe so that the value of the
powder flow rate becomes the determined target value.
CITATION LIST
Patent Document
[Patent Document 1] JP-A-06-115690
SUMMARY OF INVENTION
Objects to be Achieved by the Invention
[0005] In the occurrence of a trouble in the combustion furnace to
which the pulverized fuel is supplied, the mode of the powder
supply device may become a rapid load reduction mode where the
powder flow rate needs to be rapidly reduced. Even in the rapid
load reduction mode, however, the instant reduction of the powder
flow rate may apply load to the combustion furnace, which may
result in the trouble of the combustion furnace. In view of this,
in the rapid load reduction mode, the powder flow rate needs to be
reduced to a determined flow rate in a determined period of
time.
[0006] In this case, the rapid reduction of the powder flow rate
may be failed if the powder flow rate is reduced under the
aforementioned feedback. In view of this, in this rapid load
reduction mode, the powder discharge valve is closed to a
predetermined aperture and at the same time, the differential
pressure between the pressure in the feed tank and the pressure in
the powder delivery pipe is reduced instead of the aforementioned
feedback control so that the value of the powder flow rate becomes
the target value. In this case, however, the undershooting may be
caused in which the powder flow rate is reduced further to be lower
than the powder flow rate that is finally determined because of the
external factor such as the pressure variation at the destination
of the powder supply.
[0007] In view of this, an object of the present invention is to
provide a powder supply device and a powder supply method capable
of suppressing the undershooting of the powder flow rate while
reducing the powder flow rate rapidly.
Means for Achieving the Objects
[0008] For achieving the above object, the present invention
provides a powder supply device that supplies powder in a feed tank
to the outside of the feed tank through a powder delivery pipe
connected to the feed tank, the device including: an internal
pressure control valve that is connected to the feed tank and that
adjusts the pressure in the feed tank; a powder discharge valve
connected to the powder delivery pipe; and a controller that
controls the internal pressure control valve and the powder
discharge valve, wherein: in a rapid load reduction mode for
reducing a flow rate of powder to be supplied to the outside of the
feed tank to a predetermined rate after a predetermined period of
time, the controller sets the internal pressure control valve to an
exhaust state of reducing the pressure in the feed tank and closes
the powder discharge valve to a predetermined aperture so that the
powder flow rate becomes smaller than the predetermined rate after
the predetermined period of time; and as soon as the powder flow
rate becomes smaller than a scheduled powder flow rate that is
expected before elapse of the predetermined period of time for
reducing the powder flow rate to the predetermined rate after the
predetermined period of time, the controller controls at least one
of the internal pressure control valve and the powder discharge
valve on the basis of information of the powder flow rate so that
the powder flow rate becomes the scheduled powder flow rate.
[0009] In addition, for achieving the above object, the present
invention provides a powder supply method for supplying powder in a
feed tank to the outside of the feed tank through a powder delivery
pipe connected to the feed tank, the method including: in a rapid
load reduction mode for reducing a flow rate of powder to be
supplied to the outside of the feed tank to a predetermined rate
after a predetermined period of time, setting an internal pressure
control valve connected to the feed tank to an exhaust state of
reducing the pressure in the feed tank and closing a powder
discharge valve connected to the powder delivery pipe to a
predetermined aperture so that the powder flow rate becomes smaller
than the predetermined rate after the predetermined period of time;
and as soon as the powder flow rate becomes smaller than a
scheduled powder flow rate that is expected before elapse of the
predetermined period of time for reducing the powder flow rate to
the predetermined rate after the predetermined period of time,
adjusting at least one of the internal pressure control valve and
the powder discharge valve on the basis of information of the
powder flow rate so that the powder flow rate becomes the scheduled
powder flow rate.
[0010] In general, in the rapid load reduction mode of the powder
supply device, even when the internal pressure control valve is set
to the exhaust state and the powder discharge valve is closed to a
predetermined aperture, it is difficult to reduce the powder flow
rate just after the start of the rapid load reduction mode because
of the operation time of the device or the primary time lag.
Therefore, it is likely that the actual powder flow rate is larger
than the scheduled powder flow rate (powder flow rate that is
determined as an index according to the time in the middle of the
rapid pressure reduction mode for reducing the powder flow rate to
a predetermined rate after a predetermined period of time). Thus,
in the powder supply device and the powder supply method according
to the present invention, the pressure in the feed tank is reduced
by having the internal pressure control valve in the exhaust state
to thereby reduce the differential pressure between the pressure in
the feed tank and the pressure in the powder delivery pipe and
moreover the powder discharge valve is closed to a predetermined
aperture so that the powder flow rate becomes smaller than the
predetermined rate after the predetermined period of time in the
rapid load reduction mode. Therefore, the flow rate of the powder
to be supplied from the feed tank can be reduced rapidly. On the
other hand, after the flow rate of the powder to be supplied from
the feed tank is reduced to be less than the scheduled powder flow
rate for reducing the powder flow rate to the predetermined rate
after the predetermined period of time, at least one of the
internal pressure control valve and the powder discharge valve is
controlled based on the actual powder flow rate so that the powder
flow rate becomes the scheduled powder flow rate. In other words,
after the powder flow rate has become the scheduled powder flow
rate, at least one of the internal pressure control valve and the
powder discharge valve is subjected to the feedback control.
Therefore, the undershooting of the powder flow rate at the end of
the rapid load reduction mode can be suppressed. In this manner, in
the powder supply device according to the present invention, the
undershooting of the powder flow rate is suppressed while the
powder flow rate is reduced rapidly.
[0011] In this specification, when "the powder flow rate" is simply
referred to, this term means the flow rate of the powder that is
supplied from the feed tank and flows through the powder delivery
pipe.
[0012] The scheduled powder flow rate is preferably determined
based on the powder flow rate that is just before the rapid load
reduction mode is set. Since the appropriate scheduled powder flow
rate according to the circumstance of the powder supply before the
rapid load reduction mode can be set by determining the scheduled
powder flow rate as above, the smooth reduction of the powder flow
rate can be achieved.
[0013] In the above powder supply device, the powder flowmeter is
connected to the powder delivery pipe, and the controller
preferably controls the internal pressure control valve and the
powder discharge valve on the basis of the information from the
powder flowmeter. In the above powder supply method, the internal
pressure control valve and the powder discharge valve are
preferably adjusted on the basis of the information from the powder
flowmeter connected to the powder delivery pipe.
[0014] By adjusting the pressure in the feed tank and the powder
discharge valve on the basis of the information from the powder
flowmeter, the powder flow rate can be adjusted minutely following
the slight variation in powder flow rate. Thus, the undershooting
can be suppressed further.
[0015] In the above powder supply device, the controller preferably
sets the internal pressure control valve in the exhaust state
before the powder discharge valve is closed to the predetermined
aperture and in the above powder supply method, the internal
pressure control valve is preferably set to the exhaust state
before the powder discharge valve is closed to the predetermined
aperture.
[0016] When the powder discharge valve that discharges the powder
out of the feed tank is closed to the predetermined aperture, the
pressure in the feed tank tends to increase temporarily. Even if
the timing at which the internal pressure control valve is set to
the exhaust state and the timing at which the powder discharge
valve is closed to the predetermined aperture are simultaneous,
this tendency is caused due to the temporal delay of the exhaustion
or the like. Therefore, in the initial stage of the rapid load
reduction mode, the powder flow rate may not be reduced that much
though the powder discharge valve is closed to the predetermined
aperture for rapidly reducing the powder flow rate. In view of
this, the gas in the feed tank is exhausted before the powder
discharge valve is closed to the predetermined aperture. This makes
it possible to prevent the pressure in the feed tank from becoming
higher than the pressure before the exhaustion even though the
powder discharge valve is closed to the predetermined aperture.
Thus, the powder flow rate can be rapidly reduced.
Effect of Invention
[0017] As described above, according to the present invention, the
powder supply device and the powder supply method that can suppress
the undershooting of the powder flow rate while rapidly reducing
the powder flow rate are provided.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a diagram showing a powder supply device according
to an embodiment of the present invention.
[0019] FIG. 2 is a diagram showing a powder discharge valve.
[0020] FIG. 3 is a diagram showing a structure of a section of the
powder discharge valve.
[0021] FIG. 4 is a diagram showing a table 1.
[0022] FIG. 5 is a diagram showing a table 2.
[0023] FIG. 6 is a flowchart showing a method of adjusting the
powder flow rate in a rapid load reduction mode.
[0024] FIG. 7 is a diagram showing the scheduled powder flow rate
in the rapid load reduction mode and the change of the powder flow
rate over time.
DESCRIPTION OF EMBODIMENTS
[0025] A preferred embodiment of a powder supply device and a
powder supply method according to the present invention will be
described in detail below with reference to the drawings.
[0026] FIG. 1 is a diagram showing the powder supply device
according to the embodiment of the present invention.
[0027] As illustrated in FIG. 1, a powder supply device 1 mainly
includes: a feed tank 11 that supplies a predetermined amount of
pulverized fuel such as pulverized coal; a pressure equalizing tank
12 that stores the pulverized fuel to be supplied to the feed tank
11; an internal pressure gas supply pipe 32 that is connected to
the feed tank 11 and conveys the internal pressure gas to be
supplied to the feed tank 11; an internal pressure control valve 22
that is connected to the internal pressure gas supply pipe 32 and
adjusts the pressure in the feed tank 11; a powder delivery pipe 31
that conveys the pulverized fuel supplied from the feed tank 11; a
powder discharge valve 21 that is connected to the powder delivery
pipe 31 and adjusts the amount of pulverized fuel supplied from the
feed tank 11; a carrier gas main pipe 33 that is connected to the
powder delivery pipe 31 and introduces the carrier gas to the
powder delivery pipe 31; and a powder flowmeter 40 that detects the
flow rate of the pulverized fuel conveyed through the powder
delivery pipe 31.
[0028] The feed tank 11 and the pressure equalizing tank 12 are
metal tanks. The feed tank 11 is disposed below the pressure
equalizing tank 12, and the powder supply pipe 35 connected to a
bottom portion of the pressure equalizing tank 12 is connected to a
top portion of the feed tank 11. The pulverized fuel is supplied
from the pressure equalizing tank 12 to the feed tank 11 through
this powder supply pipe 35. A powder supply valve 25 is provided in
the middle of the powder supply pipe 35, and the start or stop of
the supply of the pulverized fuel from the pressure equalizing tank
12 to the feed tank 11 is controlled by opening or closing the
powder supply valve 25.
[0029] The feed tank 11 has a load cell 45 connected thereto, and
the weight applied from the feed tank 11 to the load cell 45 is
continuously detected by this load cell 45. The load cell 45 has a
weight indicator/controller 46 connected thereto. The weight
indicator/controller 46 measures the weight of the pulverized fuel
in the feed tank 11 continuously based on a detection signal output
from the load cell, and outputs a signal including the information
based on the weight of the pulverized fuel.
[0030] The feed tank 11 has a pressure indicator 48 connected
thereto. The pressure indicator 48 detects the pressure in the feed
tank 11 and outputs a signal including the information based on the
pressure in the feed tank 11.
[0031] In addition, the powder delivery pipe 31 is connected to a
bottom portion of the feed tank 11. The pulverized fuel supplied
from the feed tank 11 is introduced into the powder delivery pipe
31 from the feed tank 11 and conveyed by the powder delivery pipe
31 as described above.
[0032] The powder discharge valve 21 is connected in the middle of
the powder delivery pipe 31 below the feed tank 11. Therefore, the
pulverized fuel supplied from the feed tank 11 is conveyed by the
powder delivery pipe 31 through the powder discharge valve 21.
[0033] FIG. 2 is a diagram showing a part of the structure of the
powder discharge valve 21 according to this embodiment, and FIG. 3
is a diagram showing the structure of the section of the powder
discharge valve 21. As shown in FIG. 2 and FIG. 3, the powder
discharge valve 21 mainly includes a valve box 76, a set of valve
bodies 71 each housed in the valve box 76 and having an
approximately cylindrical shape, and an axial center 73 penetrating
along the axis of the valve body 71. In FIG. 3, the illustration of
the valve, box 76 is omitted for helping the understanding.
[0034] Each valve body 71 has an approximately cylindrical shape,
and a side surface 72 of each valve body 71 is provided with a
cutout 75. The axial center 73 is provided along the axis of each
valve body 71. The valve bodies 71 are disposed rotatably about the
axis with the side surfaces 72 thereof in contact with each other
in a manner that the longitudinal directions of the valve bodies 71
are in parallel to each other. This enables the portion of the side
surfaces 72 with the cutouts 75 to face each other when the valve
bodies 71 are rotated about their axes. Therefore, in the state
that their cutouts 75 face each other, the cutouts 75 form a
passage H between the valve bodies 71 as shown in FIG. 2 and FIG.
3. By the rotation of the valve bodies 71 about their axes, the
hole diameter of the passage H can be changed steplessly (the area
of the passage H on a plane along the axial center 73 can be
changed). This passage H is a hole continuing from the feed tank
11, and by adjusting the hole diameter of the passage H, the amount
of the pulverized fuel supplied from the feed tank 11 is adjusted
steplessly.
[0035] The powder discharge valve 21 has a powder discharge valve
indicator 41, and this powder discharge valve indicator 41 is
adapted to adjust the aperture of the powder discharge valve
21.
[0036] As aforementioned, the feed tank 11 is connected to the
internal pressure gas supply pipe 32 for supplying the internal
pressure gas for adjusting the pressure in the feed tank 11, and
the internal pressure gas supply pipe 32 has the internal pressure
control valve 22 connected thereto. By the aperture of the valve
connecting between the feed tank 11 and the internal pressure gas
supply pipe 32 of the internal pressure control valve 22, the
amount of the internal pressure gas to be supplied to the feed tank
11 is adjusted. In this embodiment, the internal pressure control
valve 22 has a function as the exhaust valve for reducing the
pressure in the feed tank by exhausting the gas out of the feed
tank 11. As the internal pressure control valve 22 having such a
function, a three-way valve can be given. Although not shown in
this embodiment, the internal pressure control valve 22 may include
a valve dedicated to pressure application, which is connected to
the internal pressure gas supply pipe 32 and performs only the
supply of the internal pressure gas into the feed tank 11, and a
valve dedicated to exhaustion, which is connected to the feed tank
11 and exhausts the gas out of the feed tank 11. The internal
pressure control valve 22 has an internal pressure control valve
indicator 42 connected thereto. The internal pressure control valve
indicator 42 is adapted to adjust the aperture of the valve for
exhaustion or the valve connecting between the feed tank 11 and the
internal pressure gas supply pipe 32 of the internal pressure
control valve 22.
[0037] A gas generator 30 is connected to one end of the internal
pressure gas supply pipe 32 opposite to the end thereof on the side
of the feed tank 11. Part of gas output from the gas generator 30
is introduced into the internal pressure gas supply pipe 32 and
used as internal pressure gas.
[0038] The carrier gas main pipe 33 is also connected to the gas
generator 30. The carrier gas main pipe 33 is a pipe for
introducing carrier gas for conveying the pulverized fuel into the
powder delivery pipe 31. Therefore, one end of the carrier gas main
pipe 33 opposite to the end thereof on the side of the gas
generator 30 is connected to one end of the aforementioned powder
delivery pipe 31 opposite to the end thereof on the side of the
feed tank 11 based on the powder discharge valve 21. With the
carrier gas introduced from the carrier gas main pipe 33 to the
powder delivery pipe 31, the pulverized fuel introduced from the
feed tank 11 to the powder delivery pipe 31 through the powder
discharge valve 21 is conveyed. Furthermore, a pressure indicator
43 is connected to the carrier gas main pipe 33 to detect the
pressure in the carrier gas main pipe 33 and output a signal based
on the pressure in the carrier gas main pipe 33.
[0039] Another part of the gas output from the gas generator 30 is
introduced into the carrier gas main pipe 33. Thus, the internal
pressure gas and the carrier gas are the same gas species in the
present embodiment.
[0040] Furthermore, a fluidizing gas pipe 34 is branched off from
the carrier gas main pipe 33, and an end of the fluidizing gas pipe
34 opposite to that on the side of the branch point at the carrier
gas main pipe 33 is connected to the bottom portion of the feed
tank 11. In the present embodiment, the portion where the
fluidizing gas pipe 34 is connected to the feed tank 11 is a powder
fluidizing portion 54. Part of the carrier gas flowing through the
carrier gas main pipe 33 is introduced as fluidizing gas into the
fluidizing gas pipe 34, and the fluidizing gas is introduced into
the feed tank 11 from below via the powder fluidizing portion 54.
Since part of the carrier gas is used as the fluidizing gas as
described above, the fluidizing gas and the carrier gas are the
same gas species in the present embodiment. Furthermore, the
fluidizing gas pipe 34 is provided with a fluidizing gas valve 24
in the middle portion thereof. The amount of the fluidizing gas
introduced into the feed tank 11 is adjusted by adjusting the
aperture of the fluidizing gas valve 24. Furthermore, a fluidizing
gas valve indicator 44 is connected to the fluidizing gas valve 24,
and is adapted to adjust the aperture of the fluidizing gas valve
24.
[0041] In addition, a refluidizing gas pipe 37 is branched off from
the carrier gas main pipe 33 at the different position from the
fluidizing gas pipe 34, and one end of the refluidizing gas pipe 37
opposite to that on the side of the branch point at the carrier gas
main pipe 33 is connected between the powder fluidizing portion 54
and the powder discharge valve 21 in the powder delivery pipe 31.
In this embodiment, the portion where the refluidizing gas pipe 37
is connected between the powder discharge valve 21 and the powder
fluidizing portion 54 corresponds to a powder refluidizing portion
57, and the refluidizing gas is introduced from the powder
refluidizing portion 57 to the powder delivery pipe 31. In FIG. 1,
the powder delivery pipe 31 connects between the powder
refluidizing portion 57 and the powder discharge valve 21; however,
the powder refluidizing portion 57 is preferably connected to the
powder discharge valve 21 directly. In this manner, part of the
carrier gas flowing through the carrier gas main pipe 33 is
introduced into the refluidizing gas pipe 37 as the refluidizing
gas, and the refluidizing gas is introduced from between the powder
discharge valve 21 and the powder fluidizing portion 54 through the
powder refluidizing portion 57. As described above, the
refluidizing gas pipe 37 is branched off from the carrier gas main
pipe 33, and the refluidizing gas and the carrier gas are the same
gas species in the present embodiment. Thus, all of the fluidizing
gas, the refluidizing gas, and the carrier gas are the same gas
species. Furthermore, the refluidizing gas valve 27 is provided in
a middle portion of the refluidizing gas pipe 37, and the amount of
the introduced refluidizing gas is adjusted by adjusting the
aperture of the refluidizing gas valve 27. Furthermore, a
refluidizing gas valve indicator 47 is connected to the
refluidizing gas valve 27, and is adapted to adjust the aperture of
the refluidizing gas valve 27.
[0042] In addition, a pressure indicator 49 is connected to a
portion of the powder delivery pipe 31 where the pulverized fuel is
conveyed by the carrier gas, that is, a portion downstream of the
position at the powder delivery pipe 31 to which the carrier gas
main pipe 33 is connected, and is configured to detect the pressure
in the powder delivery pipe 31 and output a signal containing
information based on the pressure in the powder delivery pipe 31. A
powder flowmeter 40 is further provided in the portion of the
powder delivery pipe 31 where the pulverized fuel is conveyed by
the carrier gas, and is adapted to detect the powder flow rate
flowing through the powder delivery pipe 31 and output a signal
containing the detected information.
[0043] In such a powder supply device, the pressure in the feed
tank 11 is higher than the pressure in the carrier gas main pipe
33, and the pressure in the carrier gas main pipe 33 is higher than
the pressure in the powder delivery pipe 31. The powder supply
device 1 is adapted to convey the pulverized fuel by utilizing the
differential pressures between these pressures. These pressures are
not particularly limited, but may be in a range of 2 MPa to 4 MPa,
for example.
[0044] By adjusting the pressure in the feed tank 11, the
differential pressure between the pressure in the feed tank 11 and
the pressure in the powder delivery pipe 31 can be adjusted. As
described above, the pulverized fuel is conveyed using the
differential pressure in the powder supply device 1; therefore, the
flow rate of the pulverized fuel to be supplied from the feed tank
11 can be adjusted by the differential pressure in addition to by
the aperture of the powder discharge valve 21. In the case of
adjusting the flow rate of the pulverized fuel by controlling the
differential pressure as above, the minute control of the powder
flow rate is possible as compared to the case where the flow rate
of the pulverized fuel is adjusted by controlling the aperture of
the powder diecharge valve 21.
[0045] The powder supply device 1 further includes a controller 60
and a memory 61 connected to the controller 60. The controller 60
is connected to the powder flowmeter 40, the pressure indicators
43, 48, and 49, and the weight indicator/controller 46. The
controller 60 accepts the input of a signal including the
information related to the powder flow rate output from the powder
flowmeter 40, a signal including the information related to the
pressure in the carrier gas main pipe 33 output from the pressure
indicator 43, a signal including the information related to the
pressure in the feed tank 11 output from the pressure indicator 48,
a signal including the information related to the pressure in the
powder delivery pipe 31 output from the pressure indicator 49, a
signal including the information related to the weight of the
pulverized fuel in the feed tank 11 output from the weight
indicator/controller 46, and the like. Then, the controller 60
generates a control signal based on the information of the memory
61 and the information from the powder flowmeter 40. On this
occasion, the controller 60 uses the signals from the pressure
indicators 43, 48, and 49, and the signal output from the weight
indicator/controller 46 as necessary. The controller 60 is
connected to the powder discharge valve indicator 41, the internal
pressure control valve indicator 42, the fluidizing gas valve
indicator 44, and the refluidizing gas valve indicator 47, and
inputs the generated control signals to those indicators.
[0046] The powder discharge valve indicator 41 is adapted to adjust
the aperture of the powder discharge valve 21 based on the control
signal from the controller 60. Therefore, in the case where the
controller 60 outputs the control signal based on the signal from
the powder flowmeter 40, the powder discharge valve indicator 41
adjusts the aperture of the powder discharge valve 21 based on the
information from the powder flowmeter 40. On the other hand, in the
case where the controller 60 outputs the control signal based on
the information of the memory 61, the powder discharge valve
indicator 41 adjusts the aperture of the powder discharge valve 21
based on the information of the memory 61.
[0047] Moreover, the internal pressure control valve indicator 42
is adapted to adjust the aperture of the exhaust valve or the
aperture of the valve connecting between the feed tank 11 and the
internal pressure gas supply pipe 32 of the internal pressure
control valve 22 based on the signal from the controller 60. As a
result, in the case where the controller 60 outputs the control
signal based on the signal from the powder flowmeter 40, the
internal pressure control valve indicator 42 adjusts the aperture
of the internal pressure control valve 22 based on the information
from the powder flowmeter 40. On the other hand, in the case where
the controller 60 outputs the control signal based on the
information of the memory 61, the internal pressure control valve
indicator 42 adjusts the aperture of the internal pressure control
valve 22 based on the information of the memory 61. Note that the
controller 60 uses the signals from the pressure indicators 43, 48,
and 49 as necessary when generating the control signal that
controls the internal pressure control valve 22.
[0048] Furthermore, the fluidizing gas valve indicator 44 is
configured to adjust the aperture of the fluidizing gas valve 24 on
the basis of a control signal from the controller 60. Therefore,
when the controller 60 outputs the control signal based on the
signal from the powder flowmeter 40, the fluidizing gas valve
indicator 44 adjusts the aperture of the fluidizing gas valve 24
based on the information from the powder flowmeter 40. On the other
hand, when the controller 60 outputs the control signal based on
the information of the memory 61, the fluidizing gas valve
indicator 44 adjusts the aperture of the fluidizing gas valve 24
based on the information of the memory 61.
[0049] Furthermore, the refluidizing gas valve indicator 47 is
configured to adjust the aperture of the refluidizing gas valve 27
on the basis of a control signal from the controller 60. Therefore,
when the controller 60 outputs the control signal based on the
aperture of the powder discharge valve 21, the refluidizing gas
valve indicator 47 adjusts the aperture of the refluidizing gas
valve 27 based on the aperture of the powder discharge valve 21. In
this case, the control signal based on the aperture of the powder
discharge valve 21 to be output from the controller may be
generated based on the control signal to be output from the
controller 60 to the powder discharge valve indicator 41. On the
other hand, when the controller 60 outputs the control signal based
on the information of the memory 61, the refluidizing gas valve
indicator 47 adjusts the aperture of the refluidizing gas valve 27
based on the information of the memory 61.
[0050] FIG. 4 is a diagram schematically showing part of the
information of the memory 61. In particular, the diagram
schematically shows a table representing the relation of the powder
flow rate, the aperture of the powder discharge valve 21, and the
differential pressure between the pressure in the feed tank 11 and
the pressure in the powder delivery pipe 31. This table is referred
to as a table 1. As shown in FIG. 4, when the powder flow rate
[kg/h] has been specified, the relation between the differential
pressure [MPa] and the aperture [%] of the powder discharge valve
21 relative to the powder flow rate is specified. For example, when
the powder flow rate is 500 [kg/h], the aperture of the powder
discharge valve 21 is 60[%] and the differential pressure is 0.03
[MPa]. Then, the controller controls the aperture of the powder
discharge valve 21 or the aperture of the internal pressure control
valve 22 on the basis of the information of the memory 61
representing the aperture of the powder discharge valve 21 as
necessary. Note that such a table in the memory 61 is obtained in
advance through experiments or the like and recorded in the memory
61.
[0051] FIG. 5 is a diagram schematically showing the information
different from the information in the table 1 in the memory 61.
Specifically, FIG. 5 is a diagram schematically showing a table
representing, in the case where the mode of the controller 60
becomes the rapid load reduction mode, the relation between the
time elapsed from the start of the rapid load reduction mode and
the scheduled powder flow rate at that time. This table is referred
to as a table 2. This scheduled powder flow rate refers to the flow
rate of the pulverized fuel to be supplied from the feed tank 11 at
that time. In other words, the scheduled powder flow rate refers to
the powder flow rate to be the index in the middle of the rapid
load mode for reducing the powder flow rate to the predetermined
rate in the predetermined period of time after the start of the
rapid load reduction mode. As shown in FIG. 5, when the elapsed
time [sec] from the start of the rapid load reduction mode has been
specified, the ratio [%] of the scheduled powder flow rate relative
to the powder flow rate that is just before the rapid load
reduction mode is set is specified. For example, when the elapsed
time from the start of the rapid load reduction mode is 20 [sec],
the scheduled powder flow rate at that time is 83.3 [%] of the
powder flow rate that is just before the rapid load reduction mode
is set.
[0052] In the powder supply device 1, the powder delivery pipe 31
is directly or indirectly connected to a combustion furnace 100 for
burning the pulverized fuel to extract energy.
[0053] Next, description is made of the operation of the powder
supply device 1 and a method of adjusting the powder flow rate of
the pulverized fuel by the powder supply device 1.
[0054] FIG. 6 is a flowchart of a method of adjusting the powder
flow rate in the rapid load reduction mode.
[0055] As shown in FIG. 6, the method of supplying the powder flow
rate by the powder supply device 1 includes STEP1 of operating the
device in a normal operation mode, STEP2 of changing the mode from
the normal operation mode to the rapid load reduction mode in which
the internal pressure control valve 22 is set to the exhaust state
and the powder discharge valve is closed to the predetermined
aperture, and STEP3 of controlling at least one of the internal
pressure control valve and the powder discharge valve on the basis
of the information of the powder flow rate.
<STEP1>
[0056] First, the powder supply device 1 is operated in the normal
operation mode. On this occasion, the feed tank 11 is already
filled with the pulverized fuel supplied from the pressure
equalizing tank 12. The fluidizing gas is introduced into the feed
tank 11 from the fluidizing gas pipe 34 through the powder
fluidizing portion 54, thereby fluidizing the pulverized fuel in
the feed tank 11.
[0057] When the flow rate of the powder to be supplied from the
feed tank 11 has been determined, the controller 60 determines the
aperture of the powder discharge valve 21 and the differential
pressure between the pressure in the feed tank 11 and the pressure
in the carrier gas main pipe 33 for the determined powder flow rate
with reference to the table 1 in the memory 61. Next, the
controller 60 transmits the control signal that determines the
aperture of the powder discharge valve 21 generated based on the
information of the memory 61 to the powder discharge valve
indicator 41, and the powder discharge valve indicator 41 adjusts
the aperture of the powder discharge valve 21 based on this control
signal. Thus, the aperture of the powder discharge valve 21 is
controlled based on the information of the memory 61. Furthermore,
the controller 60 generates the control signal that determines the
aperture of the valve, which connects between the feed tank 11 and
the internal pressure gas supply pipe 32 of the internal pressure
control valve 22, based on the table 1 of the memory 61 and the
information from the pressure indicators and 49, and transmits this
control signal to the internal pressure control valve indicator 42.
The internal pressure control valve indicator 42 adjusts the
aperture of the internal pressure control valve 22 based on this
control signal. When the aperture of the internal pressure control
valve 22 has been adjusted, the differential pressure between the
pressure in the feed tank 11 and the pressure in the powder
delivery pipe 31 is in the predetermined range. Thus, the powder is
supplied from the feed tank 11.
[0058] In the case where the amount of the refluidizing gas to be
introduced is determined based on the aperture of the powder
discharge valve 21 as described above, the aperture of the
refluidizing gas valve 27 is decreased as the aperture of the
powder discharge valve 21 is increased, in which case the amount of
the refluidizing gas to be introduced becomes smaller. In other
words, in this embodiment, the amount of the refluidizing gas to be
introduced is controlled to be in inverse proportion to the
aperture of the powder discharge valve 21.
[0059] Next, in the case where the signal including the information
of the powder flow rate from the powder flowmeter 40 indicates that
there is a difference between the determined powder flow rate and
the powder flow rate in the powder delivery pipe 31 and this
difference is in the predetermined range, the controller 60
controls the internal pressure control valve 22 to adjust the
differential pressure between the pressure in the feed tank 11 and
the pressure in the carrier gas main pipe 33. This is because the
more precise control for the powder flow rate is possible when the
differential pressure between the pressure in the feed tank 11 and
the pressure in the carrier gas main pipe 33 is adjusted by
controlling the internal pressure control valve 22 than when the
aperture of the powder discharge valve 21 is adjusted. On the other
hand, when this difference is out of the predetermined range, the
controller 60 controls the aperture of the powder discharge valve
21 again, and then controls the internal pressure control valve 22
again to adjust the differential pressure between the pressure in
the feed tank 11 and the pressure in the carrier gas main pipe 33.
In this manner, in the normal operation mode, the feedback control
is made by the signal including the information of the powder flow
rate from the powder flowmeter 40 to enable the correct adjustment
of the powder flow rate.
<STEP2>
[0060] FIG. 7 is a diagram showing the change over time of the
scheduled powder flow rate SV in the rapid load reduction mode and
the powder flow rate PV from the feed tank 11. In this embodiment,
as shown in FIG. 7, t1 represents the time at which the mode
becomes the rapid load reduction mode and t3 represents the time
after a predetermined period of time from the time t1, and the
powder flow rate to be the predetermined flow rate at the time t3
is 50% of the powder flow rate that is before the rapid load
reduction mode.
[0061] As shown in FIG. 7, upon the reception of an abnormality
signal of the combustion furnace 100 or the input of the signal
notifying the abnormality from an operator in the controller 60 at
the time t1, the mode of the controller 60 becomes the rapid load
reduction mode.
[0062] When the mode has become the rapid load reduction mode, the
controller 60 first sets the internal pressure control valve 22 to
the exhaust state. In other words, in this embodiment, the aperture
of the valve connecting between the feed tank 11 and the internal
pressure gas supply pipe 32 of the internal pressure control valve
22 is decreased to set the exhaust valve for reducing the pressure
in the feed tank by exhausting the gas in the feed tank 11 to have
the predetermined aperture, thereby exhausting the gas in the feed
tank 11. This reduces the differential pressure between the
pressure in the feed tank and the pressure in the powder delivery
pipe 31 to reduce the pressure that extrudes the powder. After
that, the controller 60 controls to close the powder discharge
valve 21 to the predetermined aperture. The period after the
internal pressure control valve 22 is set to the exhaust state and
before the powder discharge valve 21 is closed to the predetermined
aperture is not particularly limited but is 3 seconds, for example.
By setting the internal pressure control valve 22 to the exhaust
state and closing the powder discharge valve 21 to the
predetermined aperture, the flow rate of the powder supplied from
the feed tank 11 is reduced. On this occasion, the internal
pressure control valve 22 and the powder discharge valve 21 are
controlled without the feedback of the information related to the
powder flow rate from the powder flowmeter so that the average of
the inclination of the powder flow rate PV after the powder flow
rate PV starts to drop is increased in the negative direction as
compared with the average of the inclination of the scheduled
powder flow rate SV. In other words, the internal pressure control
valve 22 is set to the exhaust state and the powder discharge valve
21 is closed to the predetermined aperture so that the powder flow
rate becomes smaller than the predetermined flow rate (50% of the
powder flow rate that is before the mode becomes the rapid load
reduction mode) after the predetermined period of time (at the time
t3). The control of the internal pressure control valve 22 and the
powder discharge valve 21 is obtained by experiments in advance. As
described above, the powder discharge valve 21 in this embodiment
has the hole diameter of the passage H changeable steplessly,
whereby the amount of the pulverized fuel to be supplied from the
feed tank 11 can be adjusted steplessly. Therefore, when the mode
is the urgent load reduction mode, the pressure reduction in the
feed tank 11 by the internal pressure control valve 22 and the
aperture of the powder discharge valve 21 can be balanced.
[0063] Moreover, the reason why the internal pressure control valve
22 is set to the exhaust state before the powder discharge valve 21
is closed to the predetermined aperture when the mode is the rapid
load reduction mode is as follows. When the powder discharge valve
21 is closed to the predetermined aperture, the pressure in the
feed tank 11 tends to increase temporarily. Even if the timing at
which the internal pressure control valve 22 is set to the exhaust
state and the timing at which the powder discharge valve 21 is
closed to the predetermined aperture are simultaneous, this
tendency is caused due to the temporal delay of the exhaustion or
the like. Therefore, in the initial stage of the rapid load
reduction mode, the powder flow rate may not be reduced as much as
expected even though the powder discharge valve is closed to the
predetermined aperture for rapidly reducing the powder flow rate.
In view of this, the gas in the feed tank 11 is exhausted before
the powder discharge valve 21 is closed to the predetermined
aperture. As a result, even though the powder discharge valve 21 is
closed to the predetermined aperture, the pressure in the feed tank
11 is prevented from becoming higher than the pressure before the
exhaustion. Thus, the powder flow rate can be rapidly reduced by
controlling the internal pressure control valve 22 and the powder
discharge valve 21 in this manner.
[0064] In the rapid load reduction mode, the controller 60 compares
the scheduled powder flow rate SV and the actual powder flow rate
PV. The scheduled powder flow rate SV in FIG. 7 is obtained so that
the decrease in powder flow rate is constant in the case where the
powder flow rate is decreased to the predetermined flow rate after
the predetermined period of time. The information in which the
decrease in powder flow rate is set constant so that the scheduled
powder flow rate SV of this embodiment after 60 seconds becomes
50.0% of the powder flow rate that is before the rapid load
reduction mode is represented based on the table 2 of the memory 61
of FIG. 5. The actual powder flow rate PV is represented based on
the information from the powder flowmeter 40.
[0065] As described above, the flow rate of the powder supplied
from the feed tank 11 is reduced in the rapid load reduction mode.
As shown in FIG. 7, however, the powder flow rate PV does not start
to decrease just after the mode has become the rapid load reduction
mode but starts to decrease after a predetermined period of time
because of the time required for operating the internal pressure
control valve 22 or the powder discharge valve 21 or the temporal
delay after the start of the operation of the internal pressure
control valve 22 or the powder discharge valve 21. Therefore, for a
while after the mode becomes the rapid load reduction mode, the
powder flow rate PV from the feed tank 11 transits more than the
scheduled powder flow rate SV.
[0066] As the time elapses, the difference between the powder flow
rate PV and the scheduled powder flow rate SV is reduced and at the
time t2, the difference between the powder flow rate PV and the
scheduled powder flow rate SV no longer exists.
<STEP3>
[0067] As soon as the powder flow rate PV becomes smaller than the
scheduled powder SV, the controller 60 controls at least one of the
internal pressure control valve 22 and the powder discharge valve
21 on the basis of the information related to the powder flow rate
from the powder flowmeter 40 so that the powder flow rate PV
becomes the scheduled powder flow rate SV. In other words, the
controller 60 performs the feedback control on at least one of the
internal pressure control valve 22 and the powder discharge valve
21 by using the information related to the powder flow rate from
the powder flowmeter 40 so that the powder flow rate PV gets closer
to the scheduled powder SV. The powder flow rate PV from the feed
tank 11 is smaller than the scheduled powder flow rate SV just
after the elapse of the time t2; therefore, in the case of
controlling the internal pressure control valve 22 at this time,
the controller 60 controls to reduce the exhaustion from the feed
tank 11 and in the case of controlling the powder discharge valve
21 at this time, the controller 60 controls the aperture to open
the powder discharge valve 21. Note that the more precise control
for the powder flow rate is possible when the differential pressure
between the pressure in the feed tank 11 and the pressure in the
carrier gas main pipe 33 is adjusted than when the aperture of the
powder discharge valve 21 is adjusted. Therefore, it is preferable
that the internal pressure control valve 22 is controlled with the
aperture of the powder discharge valve 21 fixed.
[0068] At the time t3, the amount of powder becomes the
predetermined amount and the rapid load reduction mode ends.
[0069] Thus, the flow rate of the powder to be supplied to the
combustion furnace 100 is rapidly decreased. Just after the end of
the rapid load reduction mode, the control for increasing the
powder flow rate is not made again and the normal control to make
the powder flow rate the predetermined flow rate is continued until
another instruction is made.
[0070] As described above, in the powder supply device 1 according
to this embodiment, the pressure in the feed tank 11 is reduced by
having the internal pressure control valve 22 in the exhaust state
in the rapid load reduction mode, whereby the differential pressure
between the pressure in the feed tank 11 and the pressure in the
powder delivery pipe is reduced and in addition, the powder
discharge valve 21 is closed to the predetermined aperture. Thus,
the flow rate of the powder to be supplied from the feed tank 11
can be reduced rapidly. After the flow rate of the powder supplied
from the feed tank 11 is reduced to be smaller than the scheduled
powder flow rate for reducing the powder flow rate to the
predetermined flow rate after the predetermined period of time, at
least one of the internal pressure control valve 22 and the powder
discharge valve 21 is subjected to the feedback control by the
information from the powder flowmeter 40. Therefore, the
undershooting of the powder flow rate at the end of the rapid load
reduction mode can be suppressed. In this manner, in the powder
supply device 1 of the present invention, the undershooting of the
powder flow rate is suppressed while the powder flow rate is
rapidly reduced.
[0071] Moreover, in this embodiment, the scheduled powder flow rate
is determined based on the powder flow rate that is just before the
rapid load reduction mode is set. Therefore, the flow rate can be
set to the scheduled powder flow rate that is appropriate in
accordance with the circumstance of the powder supply, and the
rapid reduction of the powder flow rate can be performed
smoothly.
[0072] While the present invention has been described above by
reference to the embodiment as an example, the present invention is
not limited thereto.
[0073] For example, in the above embodiment, as soon as the powder
flow rate PV becomes smaller than the scheduled powder flow rate SV
in STEP3, the controller 60 may control only the powder discharge
valve 21 or may control both the internal pressure control valve 22
and the powder discharge valve 21.
[0074] In the above embodiment, the internal pressure control valve
22 and the powder discharge valve 21 are controlled based on the
information of the powder flow rate from the powder flowmeter 40.
The present invention is not limited thereto, however, and the
controller 60 may calculate the powder flow rate based on the
information from the weight indicator/controller 46 and control the
internal pressure control valve 22 and the powder discharge valve
21.
[0075] In the above embodiment, other kinds of valve may be
employed as the powder discharge valve 21. For example, a ball
valve having a penetration hole with a predetermined inner diameter
in a sphere may be used.
[0076] In the above embodiment, the scheduled powder flow rate is
determined based on the powder flow rate that is just before the
rapid load reduction mode is set; however, the present invention is
not limited thereto. For example, the scheduled powder flow rate in
the rapid load reduction mode may be the flow rate not based on the
powder flow rate that is just before the rapid load reduction mode
is set. In this case, for example, the scheduled powder flow rate
in the table 2 in the memory 61 corresponds to the absolute flow
rate represented by [kg/h].
[0077] Furthermore, the pulverized fuel in the feed tank is
fluidized by the fluidizing gas and further refluidized in the
powder delivery pipe 31 in the embodiment described above, the
fluidizing and refluidizing of the pulverized fuel are not
essential.
[0078] Furthermore, although the powder supply device for supplying
powder that is pulverized fuel, such as pulverized coal, has been
described in the embodiment described above, the present invention
is not limited thereto and can be applied to a powder supply device
for supplying powder other than the pulverized fuel.
INDUSTRIAL APPLICABILITY
[0079] As described above, the present invention provides the
powder supply device and the powder supply method capable of
suppressing the undershooting of the powder flow rate while rapidly
reducing the powder flow rate, and the present invention can be
applied to a powder supply device for supplying the pulverized fuel
to the combustion furnace that is used in blast furnace facilities
or thermal power plants or other powder supply devices.
REFERENCE SIGNS LIST
[0080] 1 . . . powder supply device [0081] 11 . . . feed tank
[0082] 12 . . . pressure equalizing tank [0083] 21 . . . powder
discharge valve [0084] 22 . . . internal pressure control valve
[0085] 24 . . . fluidizing gas valve [0086] 25 . . . powder supply
valve [0087] 27 . . . refluidizing gas valve [0088] 30 . . . gas
generator [0089] 31 . . . powder delivery pipe [0090] 32 . . .
internal pressure gas supply pipe [0091] 33 . . . carrier gas main
pipe [0092] 34 . . . fluidizing gas pipe [0093] 35 . . . powder
supply pipe [0094] 37 . . . refluidizing gas pipe [0095] 40 . . .
powder flowmeter [0096] 41 . . . powder discharge valve indicator
[0097] 42 . . . internal pressure control valve indicator [0098] 43
. . . pressure indicator [0099] 44 . . . fluidizing gas valve
indicator [0100] 45 . . . load cell [0101] 46 . . . weight
indicator/controller [0102] 47 . . . refluidizing gas valve
indicator [0103] 48 . . . pressure indicator [0104] 49 . . .
pressure indicator [0105] 54 . . . powder fluidizing portion [0106]
57 . . . powder refluidizing portion [0107] 60 . . . controller
[0108] 61 . . . memory [0109] 100 . . . combustion furnace
* * * * *