U.S. patent application number 17/310835 was filed with the patent office on 2022-04-21 for powder fuel combustion apparatus and combustion method.
The applicant listed for this patent is ECO RESEARCH INSTITUTE LTD., NITTAI MACHINERY CO., LTD.. Invention is credited to Mikio KASHIWA, Takamichi MATSUSHITA, Nobutsugu TANNO.
Application Number | 20220120441 17/310835 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220120441 |
Kind Code |
A1 |
MATSUSHITA; Takamichi ; et
al. |
April 21, 2022 |
POWDER FUEL COMBUSTION APPARATUS AND COMBUSTION METHOD
Abstract
The invention provides a combustion apparatus and a combustion
method capable of ashing matter to be combusted inside a combustion
chamber efficiently without providing a device such as an unburned
combustibles measurement device and without varying the direction
of injection of air into the combustion chamber. The powder fuel
combustion apparatus 1 includes a fuel supply device 10, a primary
combustion chamber 20, a secondary combustion chamber 50, an air
supply/ash discharge device 32, and a cyclone dust collector 60. An
inclined portion 23a is formed at a bottom portion 23 of the
primary combustion chamber 20, and the inclined portion 23a
includes bottom portion air supply ports 31 and an air supply/ash
discharge device 32. The air supply/ash discharge device 32
includes a bottom portion air injection nozzle 34 and an ash
delivery device 35. The bottom portion air injection nozzle 34 has
upper and lower ends opened, and a plurality of injection ports 34a
through which air is injected are formed on a side surface. During
combustion of the powder fuel F, air having a strong wind pressure
is injected through the bottom portion air injection nozzle 34
either regularly or irregularly to agitate the powder fuel F and
achieve a good combustion state.
Inventors: |
MATSUSHITA; Takamichi;
(Tokyo, JP) ; KASHIWA; Mikio; (Ibaraki, JP)
; TANNO; Nobutsugu; (Yamagata, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECO RESEARCH INSTITUTE LTD.
NITTAI MACHINERY CO., LTD. |
Tokyo
Yamagata |
|
JP
JP |
|
|
Appl. No.: |
17/310835 |
Filed: |
February 27, 2020 |
PCT Filed: |
February 27, 2020 |
PCT NO: |
PCT/JP2020/008123 |
371 Date: |
August 26, 2021 |
International
Class: |
F23N 5/20 20060101
F23N005/20; F23C 6/04 20060101 F23C006/04; F23K 3/02 20060101
F23K003/02; F23L 9/00 20060101 F23L009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2019 |
JP |
2019-036448 |
Claims
1. A combustion apparatus for combusting a powder fuel, comprising:
a primary combustion chamber configured to combust the powder fuel
in an interior thereof, and a secondary combustion chamber
configured to combust a combustion gas discharged from the primary
combustion chamber, wherein the primary combustion chamber
comprises a fuel supply device configured to supply the powder fuel
to an interior thereof, a primary air supply port configured to
supply air to an interior thereof, and an ignition burner
configured to ignite the powder fuel in an interior thereof,
wherein a bottom portion of the primary combustion chamber
comprises an inclined portion inclined to narrow toward a lower
direction, a bottom portion air supply port configured to supply
air to an interior thereof, an ash outlet provided at a lower
position of the inclined portion, and a bottom portion air
injection nozzle having a tubular shape and arranged in a vertical
direction, the bottom portion air injection nozzle comprising
openings formed on an upper end and a lower end thereof, the lower
end positioned toward the ash outlet, and having air supplied to an
interior thereof, wherein the secondary combustion chamber
comprises a secondary burner configured to heat an interior thereof
and ignite a combustion gas discharged from the primary combustion
chamber, and a secondary air supply port configured to supply
combustion air to an interior thereof, a primary air supply device
configured to supply air to the primary air supply port and the
bottom portion air supply port, an injection air supply device
configured to supply air to the bottom portion air injection
nozzle, and a secondary air supply device configured to supply air
to the secondary air supply port, and a controller configured to
control operation of the fuel supply device, the ignition burner,
the secondary burner, the primary air supply device, the injection
air supply device, and the secondary air supply device, wherein the
controller is configured to accumulate a predetermined amount of
the powder fuel in the primary combustion chamber by the fuel
supply device, ignite the powder fuel being accumulated using the
ignition burner and activate the secondary burner to heat the
interior of the secondary combustion chamber, upon performing
gasification combustion of the powder fuel being accumulated,
activate the primary air supply device and the injection air supply
device to supply an amount of air that is smaller than an amount of
air necessary for complete combustion of the powder fuel being
accumulated through the primary air supply port, the bottom portion
air supply port, and the bottom portion air injection nozzle to
generate flammable gas inside the primary combustion chamber, upon
performing direct combustion of the powder fuel being accumulated,
activate the primary air supply device and the injection air supply
device to supply an amount of air necessary for direct combustion
of the powder fuel into the primary combustion chamber through the
primary air supply port, the bottom portion air supply port, and
the bottom portion air injection nozzle, and activate the fuel
supply device to supply the powder fuel into the primary combustion
chamber to combust the powder fuel and activate the fuel supply
device as a burner, and upon performing gasification combustion of
the powder fuel being accumulated and performing direct combustion
of the powder fuel being accumulated, activate the secondary air
supply device to supply an amount of secondary combustion air
necessary for complete combustion of the flammable gas through the
secondary air supply port to combust the flammable gas.
2. The powder fuel combustion apparatus according to claim 1,
wherein, upon performing ember combustion and ashing of the powder
fuel in the primary combustion chamber, supply of fuel by the fuel
supply device is stopped, and supply of air from the bottom portion
air injection nozzle is also stopped.
3. The powder fuel combustion apparatus according to claim 1 or 2,
wherein, upon performing gasification combustion of the powder fuel
being accumulated and upon performing direct combustion of the
powder fuel being accumulated, the controller is configured to
control the injection air supply device so as to inject air by an
amount of injection capable of agitating the powder fuel either
regularly or irregularly through the bottom portion air injection
nozzle.
4. The powder fuel combustion apparatus according to any one of
claims 1 through 3, wherein the fuel supply device comprises a fuel
hopper through which the powder fuel is loaded, a hopper injection
nozzle arranged in a vertical direction in the fuel hopper to
inject air at least to a lower direction thereof, a hopper air
supply device configured to supply air to the hopper injection
nozzle, a fuel delivery device arranged at a lower direction of the
hopper injection nozzle and delivering the powder fuel to the lower
direction, a mixing pipe in which the powder fuel and air are
mixed, and a fuel blower configured to supply air to the mixing
pipe, and upon supplying the powder fuel to the primary combustion
chamber, the controller is configured to activate the fuel blower
and also activate the fuel delivery device, mix the powder fuel and
air supplied from the fuel blower in an interior of the mixing pipe
and supply the powder fuel from the mixing pipe to the primary
combustion chamber, and activate the hopper air supply device at a
predetermined timing to inject air through the hopper injection
nozzle.
5. A combustion method of combusting a powder fuel by a powder fuel
combustion apparatus, comprising: a fuel charging step, an igniting
step, a gasification combustion step, a direct combustion step, and
an ember-ashing step, wherein the powder fuel combustion apparatus
comprises a primary combustion chamber configured to combust the
powder fuel in an interior thereof, and a secondary combustion
chamber configured to combust a gas discharged from the primary
combustion chamber, wherein the primary combustion chamber
comprises a fuel supply device configured to supply the powder fuel
to an interior thereof, a primary air supply port configured to
supply air to an interior thereof, and an ignition burner
configured to ignite the powder fuel in an interior thereof,
wherein a bottom portion of the primary combustion chamber
comprises an inclined portion inclined to narrow toward a lower
direction, a bottom portion air supply port configured to supply
air to an interior thereof, an ash outlet provided to a lower
position of the inclined portion, and a bottom portion air
injection nozzle having a tubular shape and arranged in a vertical
direction, the bottom portion air injection nozzle comprising
openings formed on an upper end and a lower end thereof, the lower
end positioned toward the ash outlet, and having air supplied to an
interior thereof, wherein the secondary combustion chamber
comprises a secondary burner configured to heat an interior
thereof, and a secondary air supply port configured to supply
combustion air to an interior thereof, a primary air supply device
configured to supply air to the primary air supply port and the
bottom portion air supply port, an injection air supply device
configured to supply air to the bottom portion air injection
nozzle, and a secondary air supply device configured to supply air
to the secondary air supply port, and a controller configured to
control operation of the fuel supply device, the ignition burner,
the secondary burner, the primary air supply device, the injection
air supply device, and the secondary air supply device, wherein the
controller is configured to accumulate a predetermined amount of
the powder fuel to the primary combustion chamber by the fuel
supply device in the fuel charging step, heat the interior of the
secondary combustion chamber by the secondary burner, and after the
interior of the secondary combustion chamber has reached a
predetermined temperature, ignite the powder fuel being accumulated
using the ignition burner in the igniting step, supply an amount of
air that is smaller than an amount of air necessary for complete
combustion of the powder fuel being accumulated through the primary
air supply port, the bottom portion air supply port, and the bottom
portion air injection nozzle to generate flammable gas in the
primary combustion chamber, introduce the flammable gas to the
secondary combustion chamber, and perform complete combustion of
the flammable gas by supplying air for secondary combustion through
the secondary air supply port in the gasification combustion step,
activate the primary air supply device and the injection air supply
device to supply an amount of air necessary for direct combustion
of the powder fuel into the primary combustion chamber through the
primary air supply port, the bottom portion air supply port, and
the bottom portion air injection nozzle, activate the fuel supply
device to supply the powder fuel into the primary combustion
chamber and perform combustion of the powder fuel to activate the
fuel supply device as a burner, introduce combustion gas discharged
from the primary combustion chamber to the secondary combustion
chamber, and perform complete combustion of the combustion gas by
supplying air for secondary combustion through the secondary air
supply port in the direct combustion step, and stop supply of fuel
by the fuel supply device and perform ember combustion and ashing
of the powder fuel remaining in the primary combustion chamber in
the ember-ashing step.
6. The powder fuel combustion method according to claim 5, wherein,
in the ember-ashing step, supply of air from the bottom portion air
injection nozzle is stopped.
7. The powder fuel combustion method according to 5 or 6, wherein,
in the gasification combustion step and the direct combustion step,
the controller is configured to control the injection air supply
device so that air is injected by an amount of injection capable of
agitating the powder fuel to the bottom portion air injection
nozzle either regularly or irregularly.
8. The powder fuel combustion method according to any one of claims
5 to 7, wherein the fuel supply device comprises a fuel hopper
through which the powder fuel is loaded, a hopper injection nozzle
arranged in a vertical direction in the fuel hopper to inject air
at least to a lower direction thereof, a hopper air supply device
configured to supply air to the hopper injection nozzle, a fuel
delivery device arranged at a lower direction of the hopper
injection nozzle and delivering the powder fuel to the lower
direction, a mixing pipe in which the powder fuel and air are
mixed, and a fuel blower configured to supply air to the mixing
pipe, and in the fuel charging step and the direct combustion step,
the controller is configured to activate the fuel blower and also
activate the fuel delivery device, mix the powder fuel and air
supplied from the fuel blower in an interior of the mixing pipe and
supply the powder fuel from the mixing pipe to the primary
combustion chamber, and activate the hopper air supply device at a
predetermined timing to inject air through the hopper injection
nozzle.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a combustion apparatus for
combusting powder fuel, and a combustion method of the combustion
apparatus.
BACKGROUND OF THE INVENTION
[0002] Hitherto, a boiler that uses pulverized coal as fuel to
perform combustion and recover combustion heat to supply
superheated vapor to power plants and the like is known (refer to
Patent Literature 1). The boiler according to Patent Literature 1
includes a furnace having a hollow shape and disposed along a
vertical direction, and three combustion burners arranged in the
vertical direction to inject pulverized coal mixture and the like
obtained by mixing solid fuel and combustion air into the
furnace.
[0003] Further, the boiler includes a furnace bottom air nozzle
that injects combustion air into the furnace below the combustion
burner in the vertical direction and a horizontal direction
adjustment device capable of adjusting a direction of injection of
combustion air through the furnace bottom air nozzle in the
horizontal direction. The boiler according to Patent Literature 1
adopts such a configuration to promote combustion of fuel inside
the furnace and suppress generation of unburned combustibles.
[0004] The boiler according to Patent Literature 1 uses, as
disclosed for example in paragraphs 0027 and 0051 of the
Publication, pulverized coal formed by mainly pulverizing coal as
powder fuel (solid fuel).
[0005] Meanwhile, the present inventors utilize a carbonized fuel
production apparatus and a carbonized fuel production method
disclosed in Patent Literature 2 to produce a high quality
carbonized fuel using synthetic resin and the like that has been
recovered mainly for reuse as material.
[0006] According to the carbonized fuel production apparatus and
the carbonized fuel production method disclosed in Patent
Literature 2, even if the quality of the synthetic resin having
been recovered is not good and the synthetic resin is not suitable
for reuse, it can still be formed into carbonized fuel having a
calory close to that of coal. Therefore, even synthetic resin that
has been recovered but is not suitable for reuse or synthetic resin
that had been disposed as landfill disposal can be regenerated as
high quality fuel, so that advantageous effects of recycling
synthetic resin and reducing the load applied on landfill disposal
sites can be achieved.
PRIOR ART LITERATURE
Patent Literature
[0007] [Patent Document 1] Japanese Patent Laid-Open Application
No. 2017-145976 [0008] [Patent Document 2] International
Publication No. WO 2018/074189
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0009] The boiler according to Patent Literature 1 includes three
combustion burners arranged in a vertical direction in a vertically
long furnace, and pulverized coal is combusted inside the furnace,
wherein unburned matter is accumulated at a bottom portion of the
furnace. According to Patent Literature 1, combustion air is
introduced through the furnace bottom air nozzle to the pulverized
coal accumulated at the bottom portion of the furnace to thereby
burn the unburned matter at the bottom of the furnace.
[0010] According further to the boiler disclosed in Patent
Literature 1, as illustrated in FIG. 9 of the publication, a hopper
for storing ashes and unburned combustibles is provided at the
bottom of the furnace. According to the boiler 1 of Patent
Literature 1, ashes and unburned combustibles stored in the hopper
are analyzed by an unburned combustibles measurement device and an
unburned combustibles analyzing device provided at the bottom of
the hopper so as to adjust a direction of injection of air through
the furnace bottom air nozzle and reduce the amount of unburned
combustibles.
[0011] The unburned combustibles measurement device, the unburned
combustibles analyzing device or the configuration of varying the
direction of injection of the air nozzle as disclosed in Patent
Literature 1 are adoptable in large-scale plants from viewpoints of
both technique and costs. However, in a small apparatus, the
configuration of the apparatus becomes complex and installation
costs are increased. Moreover, such measurement devices and
variable mechanism for the nozzle require daily maintenance
operations, and the running costs are also undesirably
increased.
[0012] In order to solve the problems mentioned above, the present
invention aims at providing a combustion apparatus and a combustion
method capable of efficiently ashing matter to be combusted in a
combustion chamber without installing the unburned combustibles
measurement device or the unburned combustibles analyzing device
and without varying the direction of injection of air into the
combustion chamber.
Means for Solving the Problem
[0013] In order to achieve the above-mentioned object, the powder
fuel combustion apparatus according to the present invention is a
combustion apparatus for combusting a powder fuel, including a
primary combustion chamber configured to combust the powder fuel in
an interior thereof, and a secondary combustion chamber configured
to combust a combustion gas discharged from the primary combustion
chamber, wherein the primary combustion chamber comprises a fuel
supply device configured to supply the powder fuel to an interior
thereof, a primary air supply port configured to supply air to an
interior thereof, and an ignition burner configured to ignite the
powder fuel in an interior thereof, wherein a bottom portion of the
primary combustion chamber comprises an inclined portion inclined
to narrow toward a lower direction, a bottom portion air supply
port configured to supply air to an interior thereof, an ash outlet
provided to a lower position of the inclined portion, and a bottom
portion air injection nozzle having a tubular shape and arranged in
a vertical direction, the bottom portion air injection nozzle
comprising openings formed on an upper end and a lower end thereof,
the lower end positioned toward the ash outlet, and having air
supplied to an interior thereof, wherein the secondary combustion
chamber comprises a secondary burner configured to heat an interior
thereof and ignite a combustion gas discharged from the primary
combustion chamber, and a secondary air supply port configured to
supply combustion air to an interior thereof, a primary air supply
device configured to supply air to the primary air supply port and
the bottom portion air supply port, an injection air supply device
configured to supply air to the bottom portion air injection
nozzle, and a secondary air supply device configured to supply air
to the secondary air supply port, and a controller configured to
control operation of the fuel supply device, the ignition burner,
the secondary burner, the primary air supply device, the injection
air supply device, and the secondary air supply device.
[0014] The controller is configured to accumulate a predetermined
amount of the powder fuel to the primary combustion chamber by the
fuel supply device, ignite the powder fuel being accumulated using
the ignition burner and activate the secondary burner to heat the
interior of the secondary combustion chamber, upon performing
gasification combustion of the powder fuel being accumulated,
activate the primary air supply device and the injection air supply
device to supply an amount of air that is smaller than an amount of
air necessary for complete combustion of the powder fuel being
accumulated through the primary air supply port, the bottom portion
air supply port, and the bottom portion air injection nozzle to
generate flammable gas inside the primary combustion chamber, upon
performing direct combustion of the powder fuel being accumulated,
activate the primary air supply device and the injection air supply
device to supply an amount of air necessary for direct combustion
of the powder fuel into the primary combustion chamber through the
primary air supply port, the bottom portion air supply port, and
the bottom portion air injection nozzle, and activate the fuel
supply device to supply the powder fuel into the primary combustion
chamber and combust the powder fuel and activate the fuel supply
device as a burner, and upon performing gasification combustion of
the powder fuel being accumulated and performing direct combustion
of the powder fuel being accumulated, activate the secondary air
supply device to supply an amount of secondary combustion air
necessary to perform complete combustion of the flammable gas
through the secondary air supply port to combust the flammable
gas.
[0015] According to the powder fuel combustion apparatus of the
present invention, upon performing gasification combustion of
accumulated powder fuel, air is supplied through the primary air
supply port, the bottom portion air supply port, and the bottom
portion air injection nozzle fixed to the primary combustion
chamber to generate flammable gas inside the primary combustion
chamber, so that air is injected not only through the primary air
supply port and the bottom portion air supply port but also through
the bottom portion air injection nozzle. Complete combustion of
powder fuel can be performed by the above-mentioned configuration
according to the present invention, so that analyzing of unburnt
components and change of angle of primary air supply nozzle and the
like become unnecessary.
[0016] Further, according to the powder fuel combustion apparatus
of the present invention, upon performing ember combustion and
ashing of the powder fuel in the primary combustion chamber, supply
of fuel by the fuel supply device can be stopped, and supply of air
from the bottom portion air injection nozzle can also be
stopped.
[0017] According to the powder fuel combustion apparatus of the
present invention, when ember combustion and ashing of the powder
fuel in the primary combustion chamber are performed, white smoke
may occur in the primary combustion chamber and the secondary
combustion chamber depending on the component of the powder fuel,
and load may be applied on devices such as a cyclone dust collector
and a bag filter arranged downstream of the secondary combustion
chamber.
[0018] Through earnest investigation, the present inventors have
discovered that regarding the occurrence of white smoke during
ember combustion and ashing, the occurrence of white smoke can be
prevented by stopping the supply of air through the bottom portion
air injection nozzle, without adopting the method of heating the
interior of the primary combustion chamber and the secondary
combustion chamber using a stabilizing burner or a secondary
burner. Therefore, upon performing ember combustion and ashing of
the powder fuel inside the primary combustion chamber, if white
smoke occurred in the primary combustion chamber and the secondary
combustion chamber, the supply of air through the bottom portion
air injection nozzle should merely be stopped.
[0019] Further according to the powder fuel combustion apparatus of
the present invention, upon performing gasification combustion of
the powder fuel being accumulated and upon performing direct
combustion of the powder fuel being accumulated, the controller can
control the injection air supply device so as to inject air by an
amount of injection capable of agitating the powder fuel either
regularly or irregularly through the bottom portion air injection
nozzle.
[0020] According to this control, the powder fuel is agitated by
the air injected either regularly or irregularly through the bottom
portion air injection nozzle, so that the powder fuel can be
prevented from being fixed to the wall surface of the bottom of the
furnace, and the powder fuel can be combusted efficiently.
[0021] Further according to the powder fuel combustion apparatus of
the present invention, the fuel supply device includes a fuel
hopper through which the powder fuel is loaded, a hopper injection
nozzle arranged in a vertical direction in the fuel hopper to
inject air at least to a lower direction thereof, a hopper air
supply device configured to supply air to the hopper injection
nozzle, a fuel delivery device arranged at a lower direction of the
hopper injection nozzle and delivering the powder fuel to the lower
direction, a mixing pipe in which the powder fuel and air are
mixed, and a fuel blower configured to supply air to the mixing
pipe, and upon supplying the powder fuel to the primary combustion
chamber, the controller can to activate the fuel blower and also
activate the fuel delivery device, mix the powder fuel and air
supplied from the fuel blower in an interior of the mixing pipe and
supply the powder fuel from the mixing pipe to the primary
combustion chamber, and activate the hopper air supply device at a
predetermined timing to inject air through the hopper injection
nozzle.
[0022] According to the present configuration, the powder fuel in
the fuel hopper can be delivered smoothly to the fuel delivery
device by the hopper air supply device, and the powder fuel can be
supplied stably into the primary combustion chamber through the
mixing pipe.
[0023] Further, the powder fuel combustion method of the present
invention is a combustion method of combusting a powder fuel by a
powder fuel combustion apparatus, including a fuel charging step,
an igniting step, a gasification combustion step, a direct
combustion step, and an ember-ashing step, wherein the powder fuel
combustion apparatus includes a primary combustion chamber
configured to combust the powder fuel in an interior thereof, and a
secondary combustion chamber configured to combust a gas discharged
from the primary combustion chamber, wherein the primary combustion
chamber includes a fuel supply device configured to supply the
powder fuel to an interior thereof, a primary air supply port
configured to supply air to an interior thereof, and an ignition
burner configured to ignite the powder fuel in an interior thereof,
wherein a bottom portion of the primary combustion chamber includes
an inclined portion inclined to narrow toward a lower direction, a
bottom portion air supply port configured to supply air to an
interior thereof, an ash outlet provided to a lower position of the
inclined portion, and a bottom portion air injection nozzle having
a tubular shape and arranged in a vertical direction, the bottom
portion air injection nozzle including openings formed on an upper
end and a lower end thereof, the lower end positioned toward the
ash outlet, and having air supplied to an interior thereof and
ignite the combustion gas discharged from the primary combustion
chamber, wherein the secondary combustion chamber comprises a
secondary burner configured to heat an interior thereof, and a
secondary air supply port configured to supply combustion air to an
interior thereof, a primary air supply device configured to supply
air to the primary air supply port and the bottom portion air
supply port, an injection air supply device configured to supply
air to the bottom portion air injection nozzle, a secondary air
supply device configured to supply air to the secondary air supply
port, and a controller configured to control operation of the fuel
supply device, the ignition burner, the secondary burner, the
primary air supply device, the injection air supply device, and the
secondary air supply device.
[0024] The controller is configured to accumulate a predetermined
amount of the powder fuel in the primary combustion chamber by the
fuel supply device in the fuel charging step, heat the interior of
the secondary combustion chamber by the secondary burner, and after
the interior of the secondary combustion chamber has reached a
predetermined temperature, ignite the powder fuel being accumulated
using the ignition burner in the igniting step, supply an amount of
air that is smaller than an amount of air necessary for complete
combustion of the powder fuel being accumulated through the primary
air supply port, the bottom portion air supply port, and the bottom
portion air injection nozzle to generate flammable gas inside the
primary combustion chamber, introduce the flammable gas to the
secondary combustion chamber, and perform complete combustion of
the flammable gas by supplying air for secondary combustion through
the secondary air supply port in the gasification combustion step,
activate the primary air supply device and the injection air supply
device to supply an amount of air necessary for direct combustion
of the powder fuel into the primary combustion chamber through the
primary air supply port, the bottom portion air supply port, and
the bottom portion air injection nozzle, activate the fuel supply
device to supply the powder fuel into the primary combustion
chamber and combust the powder fuel to activate the fuel supply
device as a burner, introduce combustion gas discharged from the
primary combustion chamber to the secondary combustion chamber, and
perform complete combustion of the combustion gas by supplying air
for secondary combustion through the secondary air supply port in
the direct combustion step, and stop supply of fuel by the fuel
supply device and perform ember combustion and ashing of the powder
fuel remaining in the primary combustion chamber in the
ember-ashing step.
[0025] The powder fuel combustion method according to the present
invention is composed of the fuel charging step, the igniting step,
the gasification combustion step, the direct combustion step, and
the ember-ashing step. In the gasification combustion step, air is
supplied through the primary air supply port, the bottom portion
air supply port and the bottom portion air injection nozzle to
generate flammable gas inside the primary combustion chamber, so
that air is injected not only through the primary air supply port
and the bottom portion air supply port but also through the bottom
portion air injection nozzle. Therefore, air is injected to the
powder fuel accumulated in the interior of the bottom portion that
is inclined to narrow toward the lower direction, so that the
powder fuel can be combusted infallibly compared to the
conventional combustion method.
[0026] According to the powder fuel combustion method of the
present invention, in the ember-ashing step, supply of air from the
bottom portion air injection nozzle can be stopped. According to
this process, the occurrence of white smoke during the ember-ashing
step of the powder fuel can be prevented.
[0027] According further to the powder fuel combustion method of
the present invention, in the gasification combustion step and the
direct combustion step, the controller can control the injection
air supply device so that air is injected by an amount of injection
capable of agitating the powder fuel to the bottom portion air
injection nozzle either regularly or irregularly. According to this
control, the powder fuel accumulated at the bottom portion of the
primary combustion chamber can be agitated, so that the powder fuel
can be combusted infallibly compared to the conventional combustion
method.
[0028] Further according to the powder fuel combustion method of
the present invention, the fuel supply device includes a fuel
hopper through which the powder fuel is loaded, a hopper injection
nozzle arranged in a vertical direction in the fuel hopper to
inject air at least to a lower direction thereof, a hopper air
supply device configured to supply air to the hopper injection
nozzle, a fuel delivery device arranged at a lower direction of the
hopper injection nozzle and delivering the powder fuel to the lower
direction, a mixing pipe in which the powder fuel and air are
mixed, and a fuel blower through which air is supplied to the
mixing pipe, and in the fuel charging step and the direct
combustion step, the controller can activate the fuel blower and
also activate the fuel delivery device, mix the powder fuel and air
supplied from the fuel blower in an interior of the mixing pipe and
supply the powder fuel from the mixing pipe to the primary
combustion chamber, and activate the hopper air supply device at a
predetermined timing to inject air through the hopper injection
nozzle.
[0029] According to the present control, during the fuel charging
step and the direct combustion step, the powder fuel in the fuel
hopper can be delivered smoothly to the fuel delivery device by the
hopper air supply device, so that the powder fuel can be supplied
stably to the primary combustion chamber from the mixing pipe.
Advantageous Effects of Invention
[0030] The present invention enables to provide a combustion
apparatus and a combustion method capable of realizing advantageous
combustion of powder fuel such as even carbonized fuel mainly
composed of recovered synthetic resin and waste plastic.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is an explanatory view illustrating a power
generation system including a powder fuel combustion apparatus
according to a present embodiment.
[0032] FIG. 2 is an explanatory view illustrating a fuel supply
device according to the powder fuel combustion apparatus of the
present embodiment.
[0033] FIG. 3 is an explanatory view illustrating a configuration
of a bottom portion of a primary combustion chamber according to
the powder fuel combustion apparatus of the present embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Next, a powder fuel combustion apparatus and a powder fuel
combustion method according to one example of an embodiment of the
present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is an explanatory view illustrating the power generation
system including the powder fuel combustion apparatus according to
the present embodiment. FIG. 2 is an explanatory view illustrating
a fuel supply device in the powder fuel combustion apparatus
according to the present embodiment. FIG. 3 is an explanatory view
illustrating a configuration of a bottom portion of a primary
combustion chamber of the powder fuel combustion apparatus
according to the present embodiment. According to the present
embodiment, powdered char that is made from waste plastic produced
using the carbonized fuel production apparatus disclosed in Patent
Literature 2 is used as powder fuel.
[0035] A powder fuel combustion apparatus 1 according to the
present embodiment is a combustion apparatus adopted in a power
generation system 2 using powder fuel F, as illustrated in FIG. 1.
The power generation system 2 includes, in addition to the powder
fuel combustion apparatus 1, a boiler 3, a dust collecting device
4, a power generating device 5, a smokestack 6, and a controller 7
for controlling the devices.
[0036] The powder fuel combustion apparatus 1 includes, as
illustrated in FIG. 1, a fuel supply device 10, a primary
combustion chamber 20, a secondary combustion chamber 50, an air
supply/ash discharge device 32, and a cyclone dust collector 60. An
outlet of the cyclone dust collector 60 is connected to the boiler
3.
[0037] The primary combustion chamber 20 has an overall cylindrical
shape according to the present embodiment, and it is composed of a
ceiling portion 21 positioned at an upper portion thereof, a body
portion 22 positioned at a lower side of the ceiling portion 21,
and a bottom portion 23 positioned at a lower side of the body
portion 22.
[0038] A primary exhaust port 24 through which a flammable gas or a
combustion gas generated in the primary combustion chamber 20 is
discharged is formed to the ceiling portion 21. Further, a first
temperature sensor 25 for detecting the temperature of a combustion
gas generated in the primary combustion chamber 20 is provided in
the primary exhaust port 24. The primary exhaust port 24 can be
formed on a top panel of the ceiling portion 21 as illustrated in
FIG. 1, or it can be formed on a side wall thereof.
[0039] The fuel supply device 10 is connected to the body portion
22. The fuel supply device 10 includes a fuel hopper 11 through
which a powder fuel F is charged, a mixing pipe 12 in which the
powder fuel F and combustion air are mixed, a fuel delivery device
13 for supplying the powder fuel F charged in the fuel hopper 11 to
the mixing pipe 12 by an arbitrary amount of supply, a blower for
fuel 14 for supplying combustion air to the mixing pipe 12, and a
burner port 15 disposed at a tip portion of the mixing pipe 12.
[0040] A hopper injection nozzle 16 having a tubular shape and
extending in a vertical direction is disposed in a center of the
fuel hopper 11. The hopper injection nozzle 16 is a tubular shaped
member having upper and lower end potions opened, and a plurality
of injection ports 16a are formed on a side surface thereof through
which air is injected. A lower end portion of the hopper injection
nozzle 16 is disposed toward an opening portion 11a of the fuel
hopper 11. Further, a hopper air supply device 18 composed of an
air compressor 70, a solenoid valve for fuel 17 and an air supply
pipe for fuel 16b is connected to the hopper injection nozzle
16.
[0041] The fuel delivery device 13 of the fuel supply device 10
delivers the powder fuel F by rotation of a rotary valve 13b inside
a case 13a having a cylindrical shape. An amount of delivery per
time of fuel is controlled by subjecting a motor not shown to
inverter control and adjusting a rotational frequency of the rotary
valve 13b.
[0042] An amount of air blow of the blower for fuel 14 of the fuel
supply device 10 can also be adjusted by subjecting a motor not
shown to inverter control. An air-fuel ratio of fuel blown out
through the burner port 15 can be changed by adjusting the amount
of delivery of the powder fuel F of the fuel delivery device 13 and
the amount of air blow of the blower for fuel 14.
[0043] In a state where combustion is performed in the primary
combustion chamber 20 of the fuel supply device 10, when the powder
fuel F and combustion air are supplied through the burner port 15
to the primary combustion chamber 20, the powder fuel F is ignited
near the burner port 15, by which the burner port serves as a
burner thereafter to perform combustion.
[0044] Further, a plurality of primary air supply ports 26 for
supplying primary combustion air into the primary combustion
chamber 20 are provided on a peripheral wall of the body portion
22. Air is supplied to the primary air supply ports 26 from a
primary air blower 27 which is a primary air supply device disposed
on an outer side of the body portion 22.
[0045] Further, a steam inlet port 28 and a vent gas inlet port 29
are provided on an upper position of the body portion 22. These
inlet ports can be used to introduce steam and vent gas into the
primary combustion chamber 20 as needed. As for steam, steam
containing smell components recovered during production of fuel by
a fuel production apparatus disclosed in Patent Literature 2 and
the like can be introduced. As for vent gas, gas recovered during
production of fuel by the fuel production apparatus disclosed in
Patent Literature 2 can be used.
[0046] Further, the body portion 22 is provided with a stabilizing
burner 30 that helps combustion inside the primary combustion
chamber 20, and a stabilizing solenoid valve 30a for supplying air
to the stabilizing burner 30. For example, a vent oil that has been
recovered during fuel production by the fuel production apparatus
disclosed in Patent Literature 2 is used as the fuel for the
stabilizing burner 30.
[0047] An inclined portion 23a that is inclined to narrow toward
the lower direction from a wall surface of the body portion 22 is
formed at the bottom portion 23 of the primary combustion chamber
20, and an ash outlet 23b is formed below the inclined portion 23a.
The inclined portion 23a is provided with a plurality of bottom
portion air supply ports 31 that introduce combustion air to the
interior. Air is supplied from the primary air blower 27 to the
bottom portion air supply ports 31.
[0048] The bottom portion 23 is further provided with the air
supply/ash discharge device 32 that is arranged in the interior of
the inclined portion 23a and an ignition burner 33 that ignites the
powder fuel F charged in the bottom portion 23. The fuel used in
the ignition burner 33 can be kerosene or heavy oil and the
like.
[0049] The air supply/ash discharge device 32 includes a bottom
portion air injection nozzle 34 and an ash delivery device 35. The
bottom portion air injection nozzle 34 is a tubular shaped member
extending in the vertical direction, and which is positioned
approximately at a center of the inclined portion 23a. The bottom
portion air injection nozzle 34 has its upper and lower ends
opened, and a plurality of injection ports 34a through which air is
injected are provided on the side surface thereof. The lower end
portion of the bottom portion air injection nozzle 34 is arranged
toward the ash outlet 23b.
[0050] An injection air supply device 36 composed of the air
compressor 70 and a bottom portion solenoid valve 37, and a bottom
portion air supply pipe 38 are connected to the bottom portion air
injection nozzle 34. Air for injection is supplied from the
injection air supply device 36 to the bottom portion air injection
nozzle 34.
[0051] The ash delivery device 35 delivers ashes by having a rotary
valve 35b rotate inside a case 35a having a tubular shape. Further,
a water spray nozzle 39 for injecting water into a lower portion of
the case 35a is provided on the ash delivery device 35. When water
is injected through the water spray nozzle 39, the ashes inside the
case 35a are cooled and the ashes are gathered by water, by which
the ashes fall downward without being scattered.
[0052] An ash receiver 40 is arranged below the ash outlet 23b to
pool the ashes discharged through the ash outlet 23b. The ash
receiver 40 is capable of being moved by a moving unit such as a
forklift from the position below the ash outlet 23b to an ash
recovery location.
[0053] In addition to the above, the powder fuel combustion
apparatus 1 is provided with a vent oil tank 71 for supplying vent
oil serving as fuel to the stabilizing burner 30, a water tank 72
for supplying water to the water spray nozzle 39, and so on.
[0054] The secondary combustion chamber 50 is a combustion chamber
having a cylindrical shape to which is connected the primary
exhaust port 24 through which combustion gas of the primary
combustion chamber 20 is introduced. A secondary burner 51 for
igniting combustion gas is provided near a connecting portion of
the primary exhaust port 24. A plurality of secondary air supply
ports 52 for supplying secondary combustion air for performing
secondary combustion are provided to the peripheral wall of the
secondary combustion chamber 50. Air is supplied to the secondary
air supply ports 52 from a secondary air blower 53 serving as a
secondary air supply device.
[0055] A secondary exhaust port 54 which is connected to the
cyclone dust collector 60 is provided downstream of the secondary
combustion chamber 50. The secondary exhaust port 54 is provided
with a second temperature sensor 55 for detecting temperature of
combustion gas of the secondary combustion chamber 50. Further, a
cyclone recovery device 61 is provided below the cyclone dust
collector 60.
[0056] The cyclone recovery device 61 is composed of a rotary valve
62 and a screw conveyor 63. Powder dust recovered in the cyclone
dust collector 60 is once again returned to the primary combustion
chamber 20 by the cyclone recovery device 61 and subjected to
combustion.
[0057] The boiler 3 according to the power generation system 2 of
the present embodiment is an apparatus that generates superheated
vapor and saturated vapor by heat from the exhaust gas subjected to
dust collection processing by the cyclone dust collector 60.
According to present embodiment, the boiler 3 performs heat
recovery from the exhaust gas of approximately 600.degree. C. and
lowers the outlet temperature of exhaust gas to approximately
200.degree. C.
[0058] The power generating device 5 is a device that generates
electricity by rotating a turbine not shown by steam that has been
generated in the boiler 3. A generally used device is adopted as
the power generating device 5. The steam generated in the boiler 3
can be utilized not only in the power generating device 5 but also
in auxiliary facilities such as a heating equipment.
[0059] The dust collecting device 4 is provided downstream of the
boiler 3. A bag filter and the like being widely used in general
can be adopted as the dust collecting device 4. Further, a device
for lowering the gas temperature and the like can be installed as
needed before the bag filter. Even further, other types of dust
collectors such as a centrifugal type dust collector, an electric
dust collector, or a gravity type dust collector can be adopted as
the dust collecting device 4. It may be possible to omit the dust
collecting device 4 itself, depending on the scale of the power
generation system 2 or the type of fuel being combusted.
[0060] A suction fan not shown is provided on the smokestack 6, and
the exhaust gas generated in the powder fuel combustion apparatus 1
is sucked to the smokestack 6 and released to the exterior. The
suction fan is also driven by inverter control, and the rotational
frequency thereof is controlled by signals from the controller
7.
[0061] The controller 7 is a so-called control panel that includes
various operation switches, an indicator showing operating states
of respective devices, and a computer for controlling the
respective devices (all of which are not shown). The computer of
the controller 7 is equipped with a CPU, a storage device, a
communication device and so on (all of which are not shown), and
the storage device stores programs for executing operation of the
power generation system 2 including the powder fuel combustion
apparatus 1 according to the present embodiment.
[0062] Next, a combustion method of the powder fuel combustion
apparatus 1 according to the present embodiment will be described.
The combustion method according to the present embodiment is
composed of a fuel charging step, an igniting step, a gasification
combustion step, a direct combustion step, and an ember-ashing
step. The respective steps are executed by programs stored in the
controller 7.
[0063] According to the combustion method of the present
embodiment, at first, a fuel charging step is performed. In the
fuel charging step, a predetermined amount of powder fuel F is
accumulated in the primary combustion chamber 20 using the fuel
supply device 10. The amount of powder fuel F is set so that
approximately one-third of a capacity of the primary combustion
chamber 20 is filled. The predetermined amount should preferably be
approximately one-fourth to one-half of the primary combustion
chamber 20 considering operating efficiency of the powder fuel
combustion apparatus 1, but it can be varied arbitrarily according
to the property of the powder fuel F.
[0064] In the fuel charging step, at first, the fuel supply device
10 is started in a state where the powder fuel F is charged in the
fuel hopper 11 of the fuel supply device 10. The charging of the
powder fuel F to the fuel hopper 11 can be controlled by the
controller 7 using a conveyor, or by manually operating the
conveyor or the like.
[0065] When the fuel supply device 10 is started by the controller
7, the rotary valve 13b is rotated and the powder fuel F in the
fuel hopper 11 is conveyed to the lower part of the case 13a by the
rotary valve 13b. In this state, air for injection is sent at a
predetermined timing from the hopper air supply device 18 to the
hopper injection nozzle 16 in the fuel hopper 11. Thereby, the
powder fuel F in the fuel hopper 11 is conveyed to the lower part
of the case 13a by the rotary valve 13b without causing bridging or
the like.
[0066] The timing for activating the hopper air supply device 18
can be varied arbitrarily according to the state of the powder fuel
F, and for example, the hopper air supply device 18 can be
activated every one to ten minutes or can be activated each time
the powder fuel F is added to the fuel hopper 11.
[0067] Meanwhile, the operation of the blower for fuel 14 is also
started, and air is supplied to the mixing pipe 12. The powder fuel
F and the supplied air are mixed in the mixing pipe 12 and
discharged frontward through the burner port 15.
[0068] In this state, the ignition burner 33 and the stabilizing
burner 30 are not activated in the primary combustion chamber 20,
so that the powder fuel F discharged from the fuel supply device 10
is accumulated at the bottom portion 23 of the primary combustion
chamber 20. The operation of the fuel supply device 10 is continued
until approximately one-third of the capacity of the primary
combustion chamber 20 is filled, and after a predetermined amount
of the powder fuel F has been supplied, the operation of the fuel
supply device 10 is stopped.
[0069] Next, according to the combustion method of the present
embodiment, the igniting step is performed. In the igniting step,
at first, combustion of the secondary burner 51 of the secondary
combustion chamber 50 is started, and the temperature inside the
secondary combustion chamber 50 is raised. After the temperature of
the secondary combustion chamber 50 has reached a predetermined
temperature (such as 800.degree. C.), the ignition burner 33 is
activated to ignite the powder fuel F accumulated in the primary
combustion chamber 20. In this state, if ignition of the powder
fuel F accumulated in the primary combustion chamber 20 has been
confirmed via the first temperature sensor 25, the ignition burner
33 is stopped.
[0070] Next, the gasification combustion step will be described. In
the gasification combustion step, a part of the powder fuel F
charged during the fuel charging step is combusted in the primary
combustion chamber 20 and generates flammable gas. Primary
combustion air is supplied to the primary combustion chamber 20
through the primary air blower 27, the primary air supply ports 26
and the bottom portion air supply ports 31.
[0071] In the gasification combustion step, an amount of air
smaller than the amount of air necessary for complete combustion of
the powder fuel F is supplied as the primary combustion air
introduced to the primary combustion chamber 20. Therefore, in the
primary combustion chamber 20, a portion of the powder fuel F is
combusted and heats the surrounding powder fuel F to gradually
expand the combustion range, so that flammable gas is generated
from the powder fuel F.
[0072] Air is supplied intermittently to the primary combustion
chamber 20 from the bottom portion air injection nozzle 34 of the
air supply/ash discharge device 32. Air is injected through upper
and lower end portions and injection ports 34a of the bottom
portion air injection nozzle 34. In this state, for example,
control is performed to inject a minute amount of air for a
predetermined time and to increase the amount of injection either
regularly or irregularly. Specifically, a small amount of air that
will not cause wind pressure that moves the powder fuel F near the
bottom portion air injection nozzle 34 is injected for five
minutes, and once every five minutes, strong air capable of
agitating the powder fuel F around the bottom portion air injection
nozzle 34 is injected.
[0073] The injection of air is not limited to regular injection
performed every five minutes, for example, and air can be injected
normally at a weak wind pressure, wherein if the temperature inside
the primary combustion chamber 20 becomes equal to or lower than a
predetermined temperature, the injection of air can be performed at
such a strength that the powder fuel F is agitated. By injecting
air intermittently through the upper and lower opening portions of
the bottom portion air injection nozzle 34 and the injection ports
34a provided on the side walls thereof, the powder fuel F
accumulated at the bottom portion 23 of the primary combustion
chamber 20 is agitated and preferable combustion is performed.
[0074] If flammable gas from the primary combustion chamber 20 is
discharged into the heated secondary combustion chamber 50 during
the gasification combustion step, the flammable gas is ignited by
the secondary burner 51, and complete combustion is performed
inside the secondary combustion chamber 50.
[0075] According to the present embodiment, control is performed so
that the combustion temperature inside the secondary combustion
chamber 50 is set to 800.degree. C. or higher, preferably
900.degree. C. or higher. The secondary burner 51 stops operating
if the temperature detected by the second temperature sensor
becomes equal to the predetermined temperature or higher, but even
thereafter, combustion in the secondary combustion chamber 50 is
continued by the flammable gas from the primary combustion chamber
20.
[0076] In the gasification combustion step, the controller 7
performs control so that the combustion temperature inside the
secondary combustion chamber 50 is approximately constant. The
control of combustion temperature inside the secondary combustion
chamber 50 is performed by adjusting the amount of primary air
supplied by the primary air blower 27 in a state where a constant
amount of secondary air necessary for complete combustion of
flammable gas is supplied from the secondary air blower 53.
[0077] Further in that state, the combustion temperature inside the
secondary combustion chamber 50 can be controlled by controlling
combustion by the stabilizing burner 30. Meanwhile, even if steam
is supplied from the steam inlet port 28 and vent gas is introduced
through the vent gas inlet port 29, the combustion temperature
inside the secondary combustion chamber 50 can be controlled by
adjusting the amount of primary air supplied by the primary air
blower 27.
[0078] After complete combustion inside the secondary combustion
chamber 50, the exhaust gas is discharged through the secondary
exhaust port 54 and passed through the cyclone dust collector 60 to
be introduced to the boiler 3. In the cyclone dust collector 60,
the powder dust contained in the exhaust gas is separated and
dropped to the bottom portion of the cyclone dust collector 60. The
powder dust dropped to the bottom portion is returned to the
primary combustion chamber 20 by the rotary valve 62 and the screw
conveyor 63 of the cyclone recovery device 61 and subjected to
combustion.
[0079] The exhaust gas from which powder dust has been removed as
described above has a high temperature in the secondary exhaust
port 54, but it is subjected to heat exchange at the boiler 3 and
the temperature thereof drops before being passed through the dust
collecting device 4 and the smokestack 6 to be discharged to the
outer air.
[0080] In the boiler 3. steam is generated by the heat of exhaust
gas after combustion, and the steam is used to generate power in
the power generating device 5. According to the present embodiment,
char made from recovered plastic produced by the carbonized fuel
production apparatus according to Patent Literature 2 is used as
the powder fuel F. As described, according to the power generating
device 5, the powder fuel F serving as fuel is made from recovered
plastic, and the recovered plastic is used to generate power, so
that power can be generated with extremely small environmental
load.
[0081] When the gasification combustion step is continued for a
predetermined time, the powder fuel F accumulated in the primary
combustion chamber 20 is gradually switched from gasification
combustion to direct combustion. The switching of the combustion
state is determined based on the temperature inside the primary
combustion chamber 20 and the temperature condition inside the
secondary combustion chamber 50.
[0082] Specifically, in a state where the temperature inside the
primary combustion chamber 20 is either maintained or rising, the
gradual switching from gasification combustion to direct combustion
is detected at a timing at which the temperature of the secondary
combustion chamber 50 starts to drop. According to the control
performed by the controller 7, the amount of primary air supplied
by the primary air blower 27 is adjusted to make the combustion
temperature inside the secondary combustion chamber 50
constant.
[0083] When combustion of powder fuel F inside the primary
combustion chamber 20 advances, powder fuel F is gradually reduced,
so that the controller 7 performs control to increase the
rotational frequency of the primary air blower 27 to increase
flammable gas. If this state is advanced, the amount of powder fuel
F that has decreased in the primary combustion chamber 20 and the
amount of primary air having been increased approaches an
appropriate air-fuel ratio and approximates complete combustion, so
that the amount of flammable gas sent into the secondary combustion
chamber 50 is reduced and the temperature inside the secondary
combustion chamber 50 starts to drop. When such drop of temperature
in the secondary combustion chamber 50 is detected, the controller
7 determines that the combustion state has switched.
[0084] According to the combustion method of the present
embodiment, when the gasification combustion step ends, the
procedure advances to the direct combustion step. In the direct
combustion step, the powder fuel F accumulated in the bottom
portion 23 of the primary combustion chamber 20 continues
combustion by direct combustion. In this state, air is supplied
through the bottom portion air supply ports 31 and air is also
injected intermittently through the bottom portion air injection
nozzle 34.
[0085] In the direct combustion step, the powder fuel F is supplied
from the fuel supply device 10. When the powder fuel F is supplied
from the fuel supply device 10, the temperature inside the primary
combustion chamber 20 is in a state exceeding the ignition
temperature of the powder fuel F, so that the powder fuel F
injected from the burner port 15 is ignited and continuous
combustion is realized. As described, in the direct combustion
step, the fuel supply device 10 serves as a burner for powder
fuel.
[0086] The powder fuel F injected from the fuel supply device 10 is
supplied into the primary combustion chamber 20 while being
combusted, wherein the combusted component is discharged as
combustion gas to the secondary combustion chamber 50, and the
yet-to-be-combusted portion is accumulated inside the primary
combustion chamber 20 while being combusted. Further, the powder
fuel F supplied into the primary combustion chamber 20 is
continuously combusted by the combustion air supplied through the
primary air supply ports 26 and the bottom portion air injection
nozzle 34, and gradually ashed.
[0087] According to the combustion method of the present
embodiment, after the direct combustion step is ended, the
procedure advances to an ember-ashing step. When ending the direct
combustion step, the supply of powder fuel F by the fuel supply
device 10 is stopped. Thereby, combustion inside the primary
combustion chamber 20 is performed only by the powder fuel F
accumulated in the bottom portion 23 of the primary combustion
chamber 20, and combustion is gradually transited from direct
combustion to ember combustion, and when ember combustion is
continued, the powder fuel F is gradually ashed.
[0088] In this state, the injection of air from the bottom portion
air injection nozzle 34 is stopped, and air is supplied only
through the primary air supply ports 26 and the bottom portion air
supply ports 31. As described, by stopping the injection of air
through the bottom portion air injection nozzle 34, occurrence of
white smoke of exhaust gas discharged from the secondary combustion
chamber 50 can be prevented.
[0089] In the ember-ashing step, since combustion of powder fuel F
advances to ember combustion, the remaining powder fuel F is
gradually ashed, and in the end, it is almost completely ashed. The
ashing of powder fuel F inside the primary combustion chamber 20
can be detected by detecting the temperature inside the primary
combustion chamber 20 by the first temperature sensor 25.
[0090] Ashes of the powder fuel F having been ashed are discharged
to the exterior of the primary combustion chamber 20 by the ash
delivery device 35 of the air supply/ash discharge device 32. In
the ash delivery device 35, the rotary valve 35b is rotated to
discharge the ashes at the bottom portion 23 of the primary
combustion chamber 20 through the ash outlet 23b to the exterior.
In that state, air is injected strongly through the bottom portion
air injection nozzle 34 intermittently, so that the ashes
accumulated in the bottom portion 23 is discharged smoothly to the
exterior.
[0091] Water is injected through the water spray nozzle 39 at the
lower portion of the case 35a to the ashes discharged from the ash
outlet 23b, so that the temperature of the ashes in the case 35a is
lowered and ashes are gathered by water, thereby dropping down
without being scattered. The ash receiver 40 is arranged below the
ash outlet 23b to store the ashes discharged through the ash outlet
23b and deliver the ashes to a recovery location via a forklift and
the like as needed.
[0092] As described, in the powder generation system 2 including
the powder fuel combustion apparatus 1 of the present invention,
complete combustion of the powder fuel F is performed by supplying
primary air through the fixed bottom portion air injection nozzle
34 and the bottom portion air supply ports 31. There is no need to
analyze the unburned combustibles as according to Patent Literature
1, and there is also no need to vary the supply angle of primary
air.
[0093] According further to the powder fuel combustion apparatus 1
of the present invention, air is injected intermittently to the
powder fuel F at the bottom portion 23 of the primary combustion
chamber 20 through the bottom portion air injection nozzle 34 of
the air supply/ash discharge device 32, so that the powder fuel F
can be combusted and ashed infallibly without being accumulated at
the bottom of the furnace, and discharged to the exterior of the
primary combustion chamber 20. Therefore, the powder fuel
combustion apparatus 1 according to the present invention can
combust the powder fuel F infallibly and perform energy recovery of
the power generating device 5 efficiently.
[0094] [Reference Numbers]
[0095] 1: powder fuel combustion apparatus, 2: power generation
system, 3: boiler, 4: dust collecting device, 5: power generating
device, 6: smokestack, 7: controller, 10: fuel supply device, 11:
fuel hopper, 11a: opening portion, 12: mixing pipe, 13: fuel
delivery device, 13a: case, 13b: rotary valve, 14: blower for fuel,
15: burner port, 16: hopper injection nozzle, 16a: injection port,
17: solenoid valve for fuel, 18: hopper air supply device, 20:
primary combustion chamber, 21: ceiling portion, 22: body portion,
23: bottom portion, 23a: inclined portion, 23b: ash outlet, 24:
primary exhaust port, 25: first temperature sensor, 26: primary air
supply port, 27: primary air blower, 28: steam inlet port, 29: vent
gas inlet port, 30: stabilizing burner, 31: bottom portion air
supply port, 32: air supply/ash discharge device, 33: ignition
burner, 34: bottom portion air injection nozzle, 34a: injection
port, 35: ash delivery device, 35a: case, 35b: rotary valve, 36:
injection air supply device, 37: bottom portion solenoid valve, 38:
bottom portion air supply pipe, 39: water spray nozzle, 40: ash
receiver, 50: secondary combustion chamber, 51: secondary burner,
52: secondary air supply port, 53: secondary air blower, 54:
secondary exhaust port, 55: second temperature sensor, 60: cyclone
dust collector, 61: cyclone recovery device, 62: rotary valve, 63:
screw conveyor, 70: air compressor, 71: vent oil tank, 72: water
tank.
* * * * *