U.S. patent application number 12/514826 was filed with the patent office on 2009-12-17 for coal burning boiler apparatus.
This patent application is currently assigned to IHI Corporation. Invention is credited to Toshiro Fujimori, Toshiyuki Suko, Masato Tamura, Toshihiko Yamada.
Application Number | 20090308292 12/514826 |
Document ID | / |
Family ID | 39491800 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090308292 |
Kind Code |
A1 |
Fujimori; Toshiro ; et
al. |
December 17, 2009 |
COAL BURNING BOILER APPARATUS
Abstract
In a coal burning boiler apparatus, temperature of the
pulverized coal to be fed to the boiler can be set depending on the
property of the combustion coal, so that stable ignition and
combustion can be made regardless of the property of the combustion
coal fed. Provided are a coal burning boiler 1, a coal pulverizer 2
for pulverizing massive coal 6 into fine powder, a temperature
sensor 18 for detecting temperature of the primary air 35 for
entraining the pulverized coal to the coal burning boiler,
regulators 9, 12, 13 and 14 for regulating the temperature of the
primary air and a controller for controlling the primary air
temperature regulators on the basis of detected result of the
temperature sensor so as to make the primary air have a given
temperature.
Inventors: |
Fujimori; Toshiro; (Tokyo,
JP) ; Tamura; Masato; (Tokyo, JP) ; Suko;
Toshiyuki; (Tokyo, JP) ; Yamada; Toshihiko;
(Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
IHI Corporation
Koto-ku
JP
|
Family ID: |
39491800 |
Appl. No.: |
12/514826 |
Filed: |
November 6, 2007 |
PCT Filed: |
November 6, 2007 |
PCT NO: |
PCT/JP07/01209 |
371 Date: |
May 14, 2009 |
Current U.S.
Class: |
110/185 ;
110/263 |
Current CPC
Class: |
F23K 2203/201 20130101;
F23N 2221/08 20200101; Y02E 20/348 20130101; F23K 2201/103
20130101; F23K 1/04 20130101; F23N 2221/10 20200101; F23N 3/002
20130101; Y02E 20/34 20130101; F23L 15/04 20130101 |
Class at
Publication: |
110/185 ;
110/263 |
International
Class: |
F23N 5/02 20060101
F23N005/02; F23D 1/00 20060101 F23D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 7, 2006 |
JP |
2006-330755 |
Claims
1. A coal burning boiler apparatus characterized in that it
comprises a coal burning boiler, a coal pulverizer for pulverizing
massive coal into pulverized coal, a temperature sensor for
detecting temperature of primary air entraining the pulverized coal
to said coal burning boiler, means for regulating temperature of
said primary air and a controller for controlling said regulating
means on the basis of a detected result from said temperature
sensor so as to make said primary air have a given temperature.
2. A coal burning boiler apparatus as claimed in claim 1, wherein
said primary air temperature regulating means comprises a primary
air feed pipe passing through an air preheater heated by exhaust
gas from the boiler, a primary air bypass pipe bypassing said air
preheater and joining into said primary air feed pipe, a first flow
rate regulating damper arranged in said primary air feed pipe and a
second flow rate regulating damper arranged in said primary air
bypass pipe, said first and second flow rate regulating dampers
being flow-rate controlled by said controller.
3. A coal burning boiler apparatus as claimed in claim 1, wherein
said controller has data on properties of coals and data on
spontaneous ignition temperatures corresponding to said properties
of the coals, spontaneous ignition temperature corresponding to a
property of the coal supplied being calculated on the basis of said
data on the properties of the coals and said data on the
spontaneous ignition temperatures, temperature of the primary air
being set on the basis of a result of the calculation.
4. A coal burning boiler apparatus as claimed in claim 2, wherein
said controller has data on properties of coals and data on
spontaneous ignition temperatures corresponding to said properties
of the coals, spontaneous ignition temperature corresponding to a
property of the coal supplied being calculated on the basis of said
data on the coal properties and said data on the spontaneous
ignition temperatures, temperature of the primary air being set on
the basis of a result of the calculation.
5. A coal burning boiler apparatus as claimed in claim 3, wherein
said data on the properties of the coals include data of volatile
portion, fuel ratio and total moisture content.
6. A coal burning boiler apparatus as claimed in claim 4, wherein
said data on the coal properties include data of volatile portion,
fuel ratio and total moisture content.
7. A coal burning boiler apparatus as claimed in claim 3, wherein
said temperature of the primary air is temperature on the outlet
side of said coal pulverizer and set to be lower than a
corresponding ignition temperature by 20.degree. C.
8. A coal burning boiler apparatus as claimed in claim 4, wherein
said temperature of the primary air is temperature on the outlet
side of said coal pulverizer and set to be lower than a
corresponding ignition temperature by 20.degree. C.
9. A coal burning boiler apparatus as claimed in claim 1, wherein a
further temperature sensor is provided on the inlet side of said
coal pulverizer to conduct monitor for prevention of the
temperature of the primary air flowing into said coal pulverizer
from being higher than the given temperature.
Description
TECHNICAL FIELD
[0001] The present invention relates to a coal burning boiler
apparatus using coal as fuel and particularly to a coal burning
boiler apparatus which can realize proper combustion regardless
amount of volatile portions of the coal.
BACKGROUND ART
[0002] In a coal burning boiler apparatus, massive coal is
pulverized by a coal pulverizer into fine powder which is fed
together with combustion air into a combustion furnace where it is
ignited and burned. The ignition and combustion of the pulverized
coal fed to the furnace are processed such that at first volatile
portions produced by heating the pulverized coal is ignited and
then the pulverized coal itself is ignited.
[0003] Conventionally used in a coal burning boiler apparatus is
bituminous coal, which has much volatile portions, is readily
ignited and is stable in flame. In a coal burning boiler using
bituminous coal as fuel, combustion air (primary air) entraining
pulverized coal is heated by exhaust gas from a boiler, the
pulverized coal being heated by the primary air into a
predetermined temperature. As to the heating of the pulverized
coal, the temperature of the primary air is set to be substantially
80.degree. C. for stable ignition and combustion and for prevention
of spontaneous ignition during the entraining.
[0004] However, recent demand is to use inexpensive low-quality
coal with less volatile portions such as anthracite or
semi-anthracite coal or oil coke. Pulverized coal with less
volatile portions such as anthracite or semi-anthracite coal or oil
coke has difficulty in ignition and is unstable in combustion. In
order to overcome such drawbacks and ignite the pulverized coal
with less volatile portions for stable self-standing combustion,
required is feeding of the pulverized coal under high-temperature
status which enables ignition even with such less volatile
portions.
[0005] A conventional coal burning boiler, which has no means for
conducting heating depending on property of coal fuel, requires
selection of coal fuel used depending on the coal burning boiler
system. Or, in order to comply with changed fuel property,
substantial changes in the system are required.
[0006] [Patent Literature 1] JP7-167426A
SUMMARY OF INVENTION
Technical Problems
[0007] In view of the above, the invention has its object to make
it possible to set temperature of pulverized coal to be fed to a
boiler depending on property of combustion coal, thereby enabling
stable ignition and combustion regardless of the property of the
combustion coal.
Solution to Problems
[0008] The invention is directed to a coal burning boiler apparatus
comprising a coal burning boiler, a coal pulverizer for pulverizing
massive coal into pulverized coal, a temperature sensor for
detecting temperature of primary air entraining the pulverized coal
to said coal burning boiler, means for regulating temperature of
said primary air and a controller for controlling said regulating
means on the basis of a detected result from said temperature
sensor so as to make said primary air have a given temperature.
[0009] The invention is also directed to a coal burning boiler
apparatus wherein said primary air temperature regulating means
comprises a primary air feed pipe passing through an air preheater
heated by exhaust gas from the boiler, a primary air bypass pipe
bypassing said air preheater and joining into said primary air feed
pipe, a first flow rate regulating damper arranged in said primary
air feed pipe and a second flow rate regulating damper arranged in
said primary air bypass pipe, said first and second flow rate
regulating dampers being flow-rate controlled by said
controller.
[0010] The invention is also directed to a coal burning boiler
apparatus wherein said controller may have data on properties of
coals and data on spontaneous ignition temperatures corresponding
to said properties of the coals, spontaneous ignition temperature
corresponding to a property of the coal supplied being calculated
on the basis of said data on the properties of the coals and said
data on the spontaneous ignition temperatures, temperature of the
primary air being set on the basis of a result of the calculation.
The invention is also directed to a coal burning boiler apparatus
wherein said data on the properties of the coals may include data
of volatile portion, fuel ratio and total moisture content. The
invention is also directed to a coal burning boiler apparatus
wherein said temperature of the primary air is temperature on the
outlet side of said coal pulverizer and set to be lower than a
corresponding ignition temperature by 20.degree. C. The invention
is also directed to a coal burning boiler apparatus wherein a
further temperature sensor is provided on the inlet side of said
coal pulverizer to conduct monitor for prevention of the
temperature of the primary air flowing into said coal pulverizer
from being higher than the given temperature.
ADVANTAGEOUS EFFECTS OF INVENTION
[0011] Excellent effects and advantages can be obtained in the
invention. According to the invention, which comprises a coal
burning boiler, a coal pulverizer for pulverizing massive coal into
pulverized coal, a temperature sensor for detecting temperature of
primary air entraining the pulverized coal to said coal burning
boiler, means for regulating temperature of said primary air and a
controller for controlling said regulating means on the basis of a
detected result from said temperature sensor so as to make said
primary air have a given temperature, the temperature of the
primary air can be made suited for the property of the coal to
obtain optimum combustion status regardless of the property of the
coal. Thus, a low-quality coal may be used to decrease the running
cost.
[0012] According to the invention, said primary air temperature
regulating means may comprise a primary air feed pipe passing
through an air preheater heated by exhaust gas from the boiler, a
primary air bypass pipe bypassing said air preheater and joining
into said primary air feed pipe, a first flow rate regulating
damper arranged in said primary air feed pipe and a second flow
rate regulating damper arranged in said primary air bypass pipe,
said first and second flow rate regulating dampers being flow-rate
controlled by said controller, which makes it possible to regulate
the temperature of the primary air by means of the simple
structure.
[0013] According to the invention, said controller may have data on
properties of coals and data on spontaneous ignition temperatures
corresponding to said properties of the coals, spontaneous ignition
temperature corresponding to a property of the coal supplied being
calculated on the basis of said data on the properties of the coals
and said data on the spontaneous ignition temperatures, temperature
of the primary air being set on the basis of a result of the
calculation, which makes it possible to obtain optimum combustion
status regardless of the property of the coal. Thus, low-quality
coal may be used to decrease the running cost.
[0014] According to the invention, a further temperature sensor may
be arranged on the inlet side of the coal pulverizer to conduct
monitor for prevention of the temperature of the primary air
flowing into said coal pulverizer from being higher than the given
temperature.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a system diagram for a coal burning boiler
apparatus according to an embodiment of the invention;
[0016] FIG. 2 is a block diagram on a controller of the coal
burning boiler apparatus; and
[0017] FIG. 3 is a diagram illustrating flow of data processing in
the coal burning boiler apparatus.
REFERENCE SIGNS LIST
[0018] 1 coal burning boiler [0019] 2 coal pulverizer [0020] 3 air
preheater [0021] 6 massive coal [0022] 8 forced draft fan [0023] 9
primary air feed pipe [0024] 10 secondary air feed pipe [0025] 12
primary air bypass pipe [0026] 13 first flow rate regulating damper
[0027] 14 second flow rate regulating damper [0028] 15 primary air
amount regulating damper [0029] 16 flow rate sensor [0030] 17 first
temperature sensor [0031] 18 second temperature sensor [0032] 21
oxygen amount sensor [0033] 24 signal processing part [0034] 25
main controlling part [0035] 26 memory part [0036] 27 operating
part
DESCRIPTION OF EMBODIMENT
[0037] An embodiment of the invention will be described in
conjunction with the drawings.
[0038] First of all, the embodiment of a coal burning boiler
apparatus according to the invention will be described with
reference to FIG. 1.
[0039] In FIG. 1, reference numeral 1 denotes a coal burning boiler
in a coal burning boiler apparatus, for example, for power
generation or industrial purpose; 2, a coal pulverizer (mill) for
pulverizing massive coal 6 into fine powder; and 3, an air
preheater 3 for heating combustion air through exhaust heat.
[0040] Arranged on a wall of the coal burning boiler 1 are a
required number of pulverized coal burners 4 connected via a
pulverized coal feed pipe 5 to the coal pulverizer 2 which is
supplied with the massive coal 6.
[0041] Combustion air to be fed to the coal burning boiler 1 is
sucked from an air aspirator pipe 7 by a forced draft fan 8. The
pipe is branched at a discharge side of the forced draft fan 8 into
primary and secondary air feed pipes 9 and 10, respectively,
connected to the air preheater 3. The primary and secondary air
feed pipes 9 and 10 having passed through the air preheater 3 are
connected to the coal pulverizer 2 and to the pulverized coal
burners 4, respectively.
[0042] A primary air bypass pipe 12 is provided for
intercommunication of portions of the primary air feed pipe 9
upstream and downstream of the air preheater 3. The portion of the
primary air feed pipe 9 upstream of the air preheater is provided
with a first flow rate regulating damper 13; the primary air bypass
pipe 12 is provided with a second flow rate regulating damper 14; a
portion of the primary air feed pipe 9 upstream of the coal
pulverizer 2 is provided with a primary air amount regulating
damper 15.
[0043] The pulverized coal feed pipe 5 is provided with a flow rate
sensor 16 for detecting a flow rate of the air discharged from the
coal pulverizer 2. Further provided are first and second
temperature sensors 17 and 18 for detecting temperatures of the
primary air on inlet and outlet sides of the coal pulverizer 2,
respectively.
[0044] Exhaust gas produced in the coal burning boiler 1 is
discharged via an exhaust duct 19 provided with a sensor 21 for
detecting an amount of oxygen remaining in the exhaust gas as well
as the air preheater 3 downstream of the sensor 21. The exhaust gas
thus guided by the exhaust duct 19 is discharged to the atmosphere
via an exhaust gas processing unit (not shown) including for
example a dust collector and/or a desulfurizer.
[0045] FIG. 2 shows a controller 23 of the coal burning boiler
apparatus.
[0046] Flow rate of the primary air detected by the flow rate
sensor 16, temperature of the primary air on the inlet side of the
pulverizer 2 detected by the first temperature sensor 17,
temperature of the primary air on the outlet side of the pulverizer
2 detected by the second temperature sensor 18, amount of oxygen
remaining in the exhaust gas detected by the oxygen amount sensor
21 undergo required signal processings such as amplification
processing and A/D conversion processing in a signal processing
part 24 and are inputted into a main controlling part 25.
[0047] Connected to the main controlling part 25 is a memory part
26 such as a hard disk drive (HDD). Stored in the memory part 26
are required programs and data for operation of the coal burning
boiler apparatus; the required programs are, for example, sequence
program for driving and controlling the forced draft fan 8, the
first and second flow rate regulating dampers 13 and 14 and the
primary air amount regulating damper 15 and arithmetic program for
calculating optimum combustion condition depending on property of
fuel (coal) and the data are those on the properties of coals and
those on spontaneous ignition temperatures.
[0048] The data on properties of coals and on spontaneous ignition
temperatures are stored from the operating part 27 via the main
controlling part 25 into the memory part 26. Input from the
operating part 27 are various commands for driving the coal burning
boiler apparatus.
[0049] In accordance with the sequence program and the calculated
combustion conditions, the main controlling part 25 issues control
signals for the forced draft fan 8, the first and second flow rate
regulating dampers 13 and 14 and the primary air amount regulating
damper 15 and; on the basis of the issued control signals, a fan
controller 28, first and second flow rate regulating controllers 29
and 30 and a primary air amount regulating controller 31 drive and
control the forced draft fan 8, the first and second flow rate
regulating dampers 13 and 14 and the primary air amount regulating
damper 15, respectively.
[0050] A display part 32 displays, for example, input situations
from the operating part 27, the combustion conditions and operating
situations of the forced draft fan 8, the first and second flow
rate regulating dampers 13 and 14 and the primary air amount
regulating damper 15.
[0051] Next, mode of operation of the coal burning boiler apparatus
will be described.
[0052] Combustion air for the boiler is sucked by the forced draft
fan 8; the sucked air is branched by the primary and secondary air
feed pipes 9 and 10 into the primary and secondary airs 35 and 36.
The primary air 35 is further branched by the feed and bypass pipes
9 and 12 into branched primary air 35' and bypass flow 35''.
[0053] The branched primary air 35' and the secondary air 36 are
passed through the air preheater 3 and are preheated by the exhaust
gas, the preheated secondary air 36 being fed to the pulverized
coal burners 4. The bypass flow 35'' bypasses the air preheater 3
and joins into the branched primary air 35', thereby providing the
preheated primary air 35 which is sent to the coal pulverizer
2.
[0054] The pulverized coal pulverized and produced in the coal
pulverizer 2 is fed by the primary air 35 to the pulverized coal
burner 4. Temperature on the inlet side of the coal pulverizer 2 is
detected by the first temperature sensor 17; temperature on the
outlet side, i.e., temperature of the primary air 35 is detected by
the second temperature sensor 18 as primary air temperature sensor.
Detected results from the first and second temperature sensors 17
and 18 are respectively input via the signal processing part 24
into the main controlling part 25.
[0055] The temperature of the primary air 35 is set by regulation
of flow rate ratio between the branched primary air 35' and the
bypass flow 35'' and the regulation of the flow rate ratio is
conducted by the first and second flow rate regulating dampers 13
and 14. The primary air feed and bypass pipes 9 and 12 and the
first and second flow rate regulating dampers 13 and 14 provide
primary air temperature regulating means. There may be provided
further means for feeding air, in a separate pathway, to the coal
pulverizer 2 or to the primary air feed pipe 9 so as to regulate
the temperature of the primary air 35.
[0056] Flow rate of the primary air 35 supplied is detected by the
flow rate sensor 16 and the detected result is input to the
controller 23 where via the main controlling part 25 and the
primary air amount regulating controller 31, the flow rate of the
primary air 35 is controlled by the primary air amount regulating
damper 15 for proper combustion with no excess or deficiency
depending on load.
[0057] The pulverized coal fed together with the primary air 35 to
the pulverized coal burners 4 is burned further together with the
secondary air 36. After the combustion, the exhaust gas is
discharged via the exhaust duct 19.
[0058] The amount of oxygen remaining in the exhaust is detected by
the oxygen amount sensor 21 and the detected result is sent to the
controller 23 where the main controlling part 25 sets the forced
draft amount for proper remaining oxygen amount suited for the fuel
property to control the forced draft fan 8 via the fan controller
28.
[0059] Next, temperature regulation of the primary air 35 will be
illustrated in conjunction with FIG. 3.
[0060] FIG. 3 illustrates flow of data processing relating to
temperature regulation of the primary air 35, data on properties of
various kinds of coals usable for a coal burning boiler apparatus
being obtained beforehand by means of analysis and the like. The
data on the properties may include those of volatile portion, fuel
ratio (fixed carbon/volatile portions), total moisture content in
coals; data on spontaneous ignition temperatures of the respective
coals with obtained property data are obtained through experiences,
past performances and the like. The data on the properties of the
respective coals are classified for the respective coals and are
stored in the memory part 26 together with their classification
codes; data on the spontaneous ignition temperatures of the
respective coals are stored in the memory part 26 in association
with the property data or with the classification codes.
[0061] With respect to the spontaneous ignition temperatures
corresponding to the properties of the coals, spontaneous ignition
temperatures only for typical properties of coals may be obtained
to analogize spontaneous ignition temperatures for any unknown
properties of coals from the spontaneous ignition temperatures
corresponding to the known properties.
[0062] When coal to be burned is determined, property analysis is
conduced for the coal. The obtained coal property is input to the
operating part 27. In this case, if the coal property is known one,
a classification code corresponding to the known coal property is
input. The main controlling part 25 starts the combustion condition
arithmetic program to calculate spontaneous ignition temperature on
the basis of the stored property data to thereby set the
temperature of the primary air 35 on the outlet side of the coal
pulverizer 2. The temperature is set to be lower than the
spontaneous ignition temperature by a predetermined temperature,
e.g., by (approximately) 20.degree. C. so as to prevent spontaneous
ignition of the pulverized coal. For bituminous coal, the set
temperature may be about 80.degree. C.; and for anthracite or
semi-anthracite coal or oil coke, about 100.degree. C.
[0063] After the temperature of the primary air 35 on the outlet
side of the coal pulverizer 2 is set, degrees of valve openings of
the first and second flow rate regulating dampers 13 and 14 are
regulated on the basis of the set value. The temperature of the
primary air 35 on the outlet side of the coal pulverizer 2 is fed
back to the controller 23, so that flow rate regulation by the
first and second flow rate regulating dampers 13 and 14 is
conducted such that the temperature of the primary air 35 is
maintained to the set value.
[0064] The temperature of the primary air 35 on the inlet side of
the coal pulverizer 2 is detected by the first temperature sensor
17 to conduct monitor for prevention of the temperature of the
primary air 35 fed to the coal pulverizer 2 from exceeding the
spontaneous ignition temperature. If there is a possibility that
the temperature of the primary air 35 may exceed the spontaneous
ignition temperature, then the degree of opening of the second flow
rate regulating damper 14 is urgently increased to increase the
flow rate of the bypass flow 35'' to thereby lower the temperature
of the primary air 35.
[0065] Thus, regardless of property of coal, the temperature of the
primary air 35 is properly set and the pulverized coal heated by
the primary air 35 is fed to the pulverized coal burners 4 for
combustion, thereby obtaining stable ignition and combustion.
* * * * *