Note: Descriptions are shown in the official language in which they were submitted.
AN INCINERATION CONTROL APF'ARATUS ~O~
A FLU:tDIZED BE~ BO:~L.ER
TECHNICAL FIEL.D:
The present inventlon relates to a control apparatus
capable o-f controlling the amount of therma:L energy recov-
ered -from a sector of the fluidized bed o-f a boiler system
and supplied to the boller drum thereof, the boiler system
being so constructed that such combustibLe.s as municipal
refuse, industrial waste, coal or the like are lncinerated
in a so-called -fluidized bed and the boiler drwll receives
the resulting therma:l energy. The present invention relates
more particularly to the improvement of an :Lncinerat:lon
control apparatus adapted to enhance the response of the
suppressed control o-f :Lncreases and decreases :Ln steam
pressure caused by variations in the steam load by corre-
lating the steam pressure in the boiler drum with control
of the thermal energy recovered by the boiler drum.
BACKGROUND ART:
Fluidized bed boilers are widely known. However,
there has been general concern recently about boilers o-f
this type which have a construction wherein the fluidizing
medium is divided into two parts, one part being accommo-
dated in the inclneration chamber and -the other being accom-
modated in the thermal energy recovery chamber in such a
manner that the medium is circulated, thermal energy being
recovered -from the heat recovery means which takes the form
of water pipes or the like provided in the recovery chamber,
the amount of recovered thermal energy being controllable.
As for the principle o-f controlling the amount o-f
thermal energy to be recovered -from the fluidizing medium in
such a heat recovery chamber, there are known methods where-
in the contact area between the heat recovery means such as
water pipes or the like and the -fluidizing medium in the
fluidized bed in the heat recovery chamber is so varied that
the amount o~ thermal energy trans-ferred may be controlled
(i.e., the so-called slumping bed method), or wherein the
condition o-f the bed comprised of the -fluidizing medium in
the heat recovery chamber is so varied that the heat trans-
fer coe-fficient between the -fluidizing medium and the heat
3~
recovery means may be controlled. The la-tter cate~ory
includes such methods as that wherein -the condition of the
bed comprised o-f the -fluidizing medium is varied between
a -fluidized bed condition having an ex-tremely high heat
transfer coe-fficient and a -fixed bed condition having an
ex-tremely low heat trans-fer coef-ficient, heat recovery being
intermittently controlled (as disclosed in Japanese Patent
Public Disclosure No. 58-1~3937, U.S. Pa-tent No. 3,970,011
and US Paten-t No. 4,363,292), and that whereln the bowndary
between the area of the -fluidized bed condition and the
-fixed bed condition :Ls continuously varied so that heat
recovery may be controlled continuously and smoothly (as
disclosed :Ln Japanese Paten-t Public Disclosure No. 59 :l990).
Additlonally another method has recently been proposed by
the inventor o-f the present :Lnvention (as disclosed in
Japanese Patent ~ppllcation No. 62-9057) in which the fluid-
izing medium :Ln the heat recovery chamber is supplied with
air at a relatively low a:Lr velocity (or 0 Gmf - 2 Gm-f in
respect of mass velocity), the ~luidizing medium is main-
tained as a transient bed which is a typical bed conditionwith a heat trans-fer coe-fficient which will vary subs-tan-
tially linearly in relation to the air veloci-ty, -the heat
trans-fer coe-f~icient therein being continuously varied in
a substantially linear manner so that recovery of thermal
energy may be controlled continuously and smoothly.
Regarding the condition of the bed, it must be added that
although in the scienti-fic de-finition the bed in which the
air velocity is 0 Gmf - 1 Gm-f is a -fixed bed and the bed in
which the air velocity is higher than 1 Gmf is a fluidized
bed, it is commonly known that an air velocity higher than 2
Gm~ is required to form a stable fluidized bed. Further,
the term "moving bed" used herein is to be understood to
mean a bed in which a fluidizing medium is constantly
descending and moving, and this satisfactory descending
condition formed in it is not destroyed by bubbling up to
about 1.5 Gm-~ - 2.0 Gmf.
It should be pointed out here that slnce controlling
the amount O-r thermal energy recovered by a boiler drum -from
~0~ 32~3
--3--
a heat recovery chamber is particu:Larly effective ln maln-
-taining the temperature of! the flu:Ldized bed in the incln-
eration chamber within an appropriate range. this type o-f
control is regarded as bene-fi.cial because it o-f-fers the
-following advantages.
(l) ~y keeping the temperature o-f a -fluid:ized bed at
800~C to 850~C, incineration e-~'-fic:Lency may be improved (in
-the case of coal burning).
(2) By avoiding any increase in the tempera-ture o-P the
fluidized bed above 850~C, burning o-f the :fluidized bed may
be prevented (in the case o-f incinerat:Lon o-f the municipal
re-fuse).
(3) By keeping the temperature o-f -the -fl.uidized bed at
800~C - 850~C, which is a desirable level -for drom:Lte, lime
stone and the like to absorb sul-f'ur in the case o-f coal
burning, desulfurization may be e-f-fectively achieved.
(4) By avoiding any decrease in the temperature o-f the
-fluidized bed below 700~C, generation o-~ carbon monoxide may
be prevented (in the case o-f coal burning).
(5) Corrosion o~ heat recovery means such as water pipes
and the like can be prevented.
An example o-f such an apparatus -for controlling the
amount o-f thermal energy recovered -from a heat recovery
chamber which allows the advantages explained above to be
enjoyed is disclosed in US Patent No. 4,363,292 granted to
Engstrom et al. More speci-fically, according to this appa-
ratus as shown in Fig. l, the amount o-f heat recovery ~rom
a pipe lO~ as a heat recovery means in a second -fluidizing
zone lO0 will be controlled mainly depending on the tempera-
ture in a -furnace, mainly the temperature of a fluidized bed
in a -first fluidizing zone 107, with regurating the amount
; o-f heat recovery air supplied -from second boxes, through
ori-fices 102 to the second -fluidizing zone lO0 constituting
with the fluidizing medium as a heat recovery in a heat
recovery chamber, by opening or closing a control valve 104
provide at a conduit 103 in communication with the second
box lOl in accordance with a temperature control device TC
~0 al3~
respons:Lve to the temperature signal from a temperature
sensor 105 Ln the ~urnaces.
However, with a prior art fluidized bed type boiler
o-f the type explained above, it has been di-Lficult to
readily suppress any increase or decrease in the steam
pressure in the boiler drum caused by variations in the
steam load.
More speci-fically, with a -fluidized bed bo:Ller o-f
this type, it is normal practice to control the amount
of combustibles supplied to the fluidized bed in the
incineration chamber (or the fluidized bed in the -first
-fluidizing zone 107, ~or example) by detecting any variation
in the steam pressur-e so as to restrict any inf'luence due
to increases in the steam pressure in a bo:Ller drum. This
practice is al.ready well known. However, even i~ the amount
O-e combustibles suppl:Led is increased upon detecting a
reduct:Lon in the steam pressure, the thermal inertia o-f the
fluidized bed in the incineration chamber is extremely high
and hence the temperature of the fluidized bed will not
increase abruptly, but only gradually.
Accordingly, if the volume o-f air supplied -for heat
recovery to the -fluidi~ing medium in the heat recovery
chamber is controlled and the air supply is increased solely
in dependence upon the gradual increases in temperature o~
the -fluidized bed which occur in the manner explained above,
the amount of thermal energy to be recovered from the fluid-
izing medium in the heat recovery chamber (or the jet stream
bed in the second ~luidizing zone, -for example) cannot be
rapidly augmented. Thus any increase or decrease in the
steam pressure in the boiler drum caused by variations in
the steam load cannot be quickly restrlcted, the severity o-f
this phenomenon depending on the amount of recovered heat
which is to be circulated back to the boiler drum.
DISCLOSURE OF THE INV~NTlON:
It is there-fore a general object of the present
invention to solve the problems inherent to the above-
mentioned prior arts in which quick responses in the control
20(~38~
o-f varlat:Lons ln steam pressure necess:Ltated by varlatlons
i.n steam load have not been possible.
Ano-ther obJect of the present inven-tion i9 to provide
an lncineratlon contro:L apparatus for a fluidlzed bed type
boiler capable o-f quickly controlling increases or decreases
in the steam pressure in a boiler drum caused by variations
in steam load by controlling the amount of thermal energy
recovered by the boiler drum :Ln response to any variation in
steam pressure which immediately responds to varlations in
the steam load.
It is a f-urther object of the present invention to
provide an inclneration control apparatus -for a -L'luidized
bed -type boi~er which exhibits a substant:Lally enhanced
response to steam pressure controlling operations at the
time o-f varlations in the steam load by an arrangemerlt in
which the operation o-f controll.lrlg the amount of combusti-
bles being supplied in accordance with the steam pressure :Ls
correlated ~ith the operation of controlling the amount o-f
thermal energy recovered -from the heat recovery chamber in
accordance with the temperature in the incineration chamber.
It is a still -further object o-f the present invention
to provide an incineration control apparatus for a -fluidized
bed type boiler which will not inhibit response in the
operation o-f controlling increases and decreases in the
steam pressure due to external disturbance at the time o-f
a normal increase or decrease in steam load, irrespective
o~ whekher the steam load is increasing or decreasing.
Yet another obJect of the present invention is to
provide an incineration control apparatus for a fluidized
bed type boiler which will not inhibit response in the
operation of controlling decreases in the steam pressure due
to external disturbance whether the steam load is increasing
without causing a situation wherein insuf-ficient thermal
energy is recovered by the boiler drum frorn the heat
recovery chamber even when the normal steam load is
e~cessive.
According to the first embodiment o-f the presen-t
invention, there is provided a means of control]ing air
3~
--6--
supply -for heat recovery in accordance with the prevailing
steam pressuLe which is adap-ted to control the a~oun-t of
thermal energy recovered by a boiler drum *rom a heat
recovery chamber in accordance with the prevailing steam
pressure by varying the amount of air supplied to the heat
recovery chamber in accordance ~ith the steam pressure
resulting therefrom. More speci~ically, -the arrangement in
a typical embodiment is such that the operat:Lon of the rneans
-for contro:Lling the amount o~ combustibles supplLed which i~s
adapted to control the amount o-f the combustibles supplied
to the incineration chamber in accordance w:Lth -the steam
pressure :Ln the boiler drum is correla-ted with the operation
o-~ the means -for controlling air supply for heat recovery
which is adapted to control the amount of thermal energy
recovered by the boiler drum from the heat recovery chamber
by varying the amount o-f air supplied to the heat recoverY
chamber in accordance with the temperature in the incinera-
tion chamber, and a set temperature value control means i9
provided which is adapted to control in accordance with the
prevailing steam pressure in the boiler drum the set temper-
ature required in a -fluidized bed in the incineration
chamber on the basis of the control of the air supply -for
heat recovery. This arrangement provides an incineration
control apparatus for a fluidized bed type boiler which is
capable of solving the above-mentioned problems and respond-
ing immediately to variations in steam pressure so as to
instantly change the amount o~ thermal energy recovered by
the boiler drum from the heat recovery chamber, thereby
providing quick control of variations in the steam pressure.
According to the present invention as explained
above, since a control means adapted to control ~he amount
of thermal energy recovered by the boiler drum from the heat
recovery chamber in accordance with the steam temperature is
additionally provided, the amount of thermal energy recov-
ered by the boiler drum can be controlled on the basis of
variations iIl steam pressure which will immediately respond
to variations in the steam load instead o-f on the basis of
such -~actors as the temperature in -the incineration chamber
20~)~8~3
wh:Lch rnay only change gradual:l,y due to -I;hermal i,nertia.
This prov:ides the great benefit o:~ allowing increases or
decreases in the steam pressure in the boiler drurn caused
by variat:Lons in the steam load to be quickly controlled.
The control means for controlling -the amount of
thermal energy recovered ln accordance with the prevaillng
steam pressure includes a means for detecting steam pressure
adapted to output a steam pres~:ure signa~ lndicating the
steam pressure and a temperature detecting means adapted
to detect the prevailing temperature in the incineration
chamber and output temperature signals indicating the
detected temperature. Thus, the amount of combustibles
supplied is controlled in response -to the temperatllre
signals while the velocity o-f the air supply -for heat
recovery w:Lll be so controlled that the -temperature in the
incineration chamber may be kept identical to -the speci-eied
set temperature. The set temperature control means is
adapted to correlate the operational output signals from the
pressure controller which serves as the means for control-
~0 ling the amount of combustibles to be supplied with the setvalue signals from the temperature controller which serves
as the means ~or controlling the air supply for heat recov-
ery. This allows the operation Or controlling the amount
o-f combustibles supplied to the incineration chamber in
accordance with the steam pressure in the boiler drum to be
correlated with the operation of controlling the amount of
air supplied -for heat recovery 'by the boiler drum -from the
heat recovery chamber by varying the air supply to the heat
recovery chamber in accordance with the temperature in the
incineration chamber. Thus the amount o* air supplied to
the heat recovery chamber for heat recovery purposes may be
increased or decreased rather rapidly even when ~he control
operation undertaken by the means for controllinF the amount
o-f combustibles supplied is relatively long in duration, and
this ensures that the response o-f the operation of control-
ling the steam pressure a-t the time of variations in the
steam load will be improved to a substantial degree.
Z0038~E3
According to the second embod:lMent o-L the present
invention, a means -ror controlling the amount o-~ combusti-
bles supplied in accordance with the prevailing steam load
is provided in addition to the various means employed :in the
-first embodiment, the control means being adapted to operate
and generate appropriate operatiorlal output signals which
serve to continuously adJust the amount o-f combus-tibles
supp]ied in correspondence with normal increases and
decreases in the steam load which depend on -the steam -f:Low
rate prevailing during the supply o-~ operatiolla] output
signals when the pressure controller wh:Lch controls the
amount o-f combustibles supplied is in a ~alanced state.
Thus -the pressure controller wh:Lch serves as the means -for
controlling the amount Oe combustibles supplied is balanced
when in the normal condition so that the operational output
signal is kep-t at a value o-f 50% and -the amount o-f air
supplied (air velocity) for heat recovery by the means for
controlling supply for heat recovery in response to the
operational output signals is held around a median value o-f
50~~. In this way the range o:~ variation in the air supply
or the thermal energy capable o-f being recovered by the
boiler drum -from the heat recovery chamber may be maximi.zed
whether an increase or a decrease in the steam load is
taking place, and the response of the operation -for control-
ling increases and decreases in the steam pressure due toexternal disturbances will not be inhibited at all, irre-
spectlve of whether there is an lncrease or a decrease in
the steam load.
According to the third embodiment o~ -the present
invention, a means o-f controlling air supply -for incinera-
tion is provided in addition to -the various means employed
in the second embodiment, the means -for controlling air
supply for incineration being adapted to receive from the
means for controlling the amount of combustibles to be
supplied in accordance with the steam load operational
output signals which increase continuously in correspondence
with any increase in steam load and increase the amount
of air supplied (or air velocity) for incineration to the
X(~3~
incinerat:Lon chamber. Thus -the amount o~ P]uldizing rnedium
circulated in the heat recovery chamber will be increased
when the steam load increases normally and a sufficient
amount of thermal energy may be sa-fely recovered by increas-
klg the amount o-f regenerative thermal energy. Hence there
will never be a short-fall o-f thermal energy recovered by the
boiler drum -from the heat recovery chamber and the response
o-f the operation of controlling decreases in steam pressure
due to external disturbances, which involves increasing the
steam load, will not be impaired at a:L:L. This is a signi*i-
cant improvement over the prior art.
BRIEF EXPI,ANATION OF DRAWINGS:
Flg. 1 is a schematic view :Ll:Lustrat:Lng the cons-trLIc-
tion Oe a -fluidized bed type boiler according to a pr:Lor
art;
Figs. 2A, 2B, 3A, 3B and 4 are explanatory illustra-
tions showing the constitution and operation of the boiler
to be controlled by the incineration control apparatus
according to the present invention, wherein F'igs. 2A and 2B
are vertical sectional views showing -the constitution o-E the
boiler; Fig. 3A is a graph showing by way o-f example the
relationship between the air velocity (shown by the abscissa)
of the air for incineration and the amount of fluidizing
medium circulating (shown by the ordinate); Fig. 3B is a
graph showing by way o-f example the relationship between the
air velocity (shown by the abscissa) o-f the air for heat
recovery and the amount of -fluidizing medium circulating
(shown by the ordinate); and Fig. 4 is a graph showing by
way o-f example the relationship between the air velocity
(shown by the abscissa) of the air -for heat recovery and the
heat transfer coe-fficient ~ (shown by the ordinate) of the
heat recovery tube in the moving bed:
Figs. 5A, 5B and 6 show a -first embodiment of the
incineration control apparatus according to the present
invention, wherein Figs. 5A and SB are block diagrams
respectively showing the constitution o-f the embodiment;
and Fig. 6 is a graph showing by way of example the in~ut
and output characteristics o~ the signal inverter 32 which
8~3
-:1.0-
serves as the means ~or controlL:Lng the set -temperature
values;
~ igs. 7A, 7B, 8 and ~ show a second embodiment o-
~the incineration control apparatus according to the present
invention, wherein Figs. 7A and 7B are block diagrams
respectively showing the constitution o~ the embodiment;
Fig. 8 is a graph illustrat:Lng by way o-~ example the input
and output characteris-tics of the computing element 35 wh:Lch
serves as the means for controlling the amount o-~ combusti-
bles supplied in accordance with the steam load; and Fig. gis a graph showing by way Or example the relationsh:Lp
between the steam flow rate (shown by the ordinate) :Ln the
condition wherein the means 31 ~or controlllng the amourlt Oe
combustibles to be supplied is in a balanced state and the
amount of combustibles requ:Lred for generating that steam
-flow rate, or the operational output signals YO (shown by
the abscissa) -from the computing element 35; and
Figs. 10A and 10B are block diagrams showing a third
embodiment o-f the incineration control apparatus according
to the present invention.
BEST ~ODE OF CARRYING OUT THE INVENTION:
F:igs. 2A and 2B illustrate di-f~erent examples o-f
boilers which are to be controlled by the :Lncineration
control apparatus according to the present invention. In
Fig. 2A, the entire boiler A is enclosed by the wall 1 and
the incineration chamber 3 is defined by a pair o~ partition
plates 2, 2, while the heat recovery chambers 4, 4 are
de-fined between the partition plates 2, 2 and the wall o~
the boiler, respectively.
At the bottom portion o-f the incineration chamber 3
is an air chamber 6 the upper sur-~ace o-f which is covered by
an air supply plate 5 having a multiplicity o-f air supply
ports 5a. The air chamber 6 may be separated into a plural-
ity o-f sub-chambers. The air chamber 6 is connected to an
incineration air supply tube 7 coming -from the incineration
air source. A temperature sensor 3a which serves as a means
~or detecting temperature is supported at a position above
the air chamber 6. The air supply plate 5, air supply ports
~0
-11
5a and air chamber 6 together const:Ltute the means for
supplying air for inclnerat:Lon. Ins:Lde the incineration air
supply tube 7 are inserted a control valve 7a and a -f]ow
meter 7b with the former c:Loser to the source of air -for
incineration. In the bottom par-t o-f the heat recovery
chamber 4 is an air chamber 6a the upper sur-face of which
is covered by an air dispersion plate 8 (means Oe a:Lr swpply
for heat recovery) having a multiplicity of air supply ports
~a and to which is connected a heat recovery air supply tube
9 -from the source o-f a:ir for heat recovery. In the heat
recovery air supply tube are inserted a control valve 9a and
a flow meter 9b with the former closer to the sowrce o-f air
-eor heat recovery. ~ heat recovery tube 10 is SPirallD
arranged above the air dispersion plate 8 in the heat
recovery chamber 4. One end O-e the heat recovery tube 10
is directly connected to a boiler drum 17, -to be explained
later, and the other end o-f the tube lO is connected to the
boiler drum through a circulation pump 11.
The incineration chamber 3 and heat recovery chamber
4 are both filled with particles (having a particle size o-f
approx. 1 mm) o-f quartz or the like. It is to be noted that
the particles contained in the incineration chamber 3 are
permitted to flow over the upper end o-f the respective
partition plates 2 into the fluidizing medium contained in
the heat recovery chamber 4, while the particles con-tained
in the heat recovery chamber 4 are caused to re-turn to the
incineration chamber 3 through the area below the respective
partition plates 2, thus allowing circulation o-f the -fluid~
izing medium.
Disposed at an opening (not shown) -that communicates
with the incineration chamber 3 is a means 14 -for supplying
combustible~, which is equipped with a screw type -feeder 13
(see Fig. 5A) that is driven by a mo-tor 12 incorporated
therein.
~n the other hand, the boiler drum 17 is arranged
to -fit in the wall 1 of the boiler A at the upper portion
thereof in such a manner as to be surrounded by a heat
receiving water pipe 16 having a -flue opening 16a at one
2~)~38~
-12-
por~ion thereof and capab:Le of rece:Lv:Lng heat ~rom the
:Lnc:Lneratlon chamber 3. The bo:Ller drum 17 Is provlded wi-th
an upper steam drum 17a and a lower water drum 17c which is
connected to the steam drllm by rneans of a multip:llcity of
convective -tubes 17b.
A water supply pipe 19 extends -from the water source
to the steam drum 17a and the steam pipe 20 extends -from the
steam drum 17a to a steam load 21 through a stea1n separator
17d. There are provided in the steam pipe are a flow meter
20a which serves as a means -for detectlng steam flow rate
and a pressure gauge 20b which serves as a means for
detecting steam pressure. Reference numeral 22 des:lgnates
an exhaust port for combustion gas embedded in the wal:L 1 o-f
the boi].er adJacent to the boiler drum 17.
The control apparatus B is provided as a separate
unit adJacent to the boiler A which :Ls controlled by the
apparatus B. The apparatus B is received over the signal
lines the output signals respectively -from the temperature
sensor 3a, the :flow meters 7b, 9b and 20a as well as the
pressure gauge 20b. The output signals -from the control
apparatus B are supplied in turn over the signal lines to
the control valves 7a, 9a and a combustibles supplying means
14, respectively.
Fig. 2B illustrates an alternative constitut:ion of a
boiler to be controlled by the incineration control appara-
tus according to the present invention. In Fig. 2B, the
entire boiler C is enclosed by the wall 1. The incineration
chamber 3 is defined by a pair o-f re-flection partition
plates 2b, 2b with the upper end port:Lon 2a ben-t upwardly
and vertically at the central portion o-f the bottom of the
boiler below the inclined surface o-f the partition plates
whi]e the heat recovery chambers 4, 4 are defined at -the
outer periphery of the central bottom portion above the
inclined surface.
At the bottom of the incineration chamber 3 are
provided air chambers which are divided into a plurality of
sub-chambers the upper sur-face of which is covered by an air
supply plate 5 having a multiplicity o-f air supply ports 5a
;~0~3~
-13-
and arranged as a ramp lead:lng toward the center o-f the
bottom portion of the incineration chamber. The air chamber
6 is connected to the incineration air tube 7 -Prom the
source of air -~or incineration. The temperature sensor 3a
which serves as the means Por detecting terrlperature is
supported above the chamber. The air supply plate 5, air
supply ports 5a and air chamber 6 toge-ther constitute the
incineration air supply means. Inside the incineration alr
tube 7 are inserted in series a control v~lve 7a and a -flow
meter 7b with the former closer to the air- inclnera-tion
source. On the other hand, mu:ltiple rows oP cylindrical
air dispersion -tubes 8b are provided extending along the
inclined upper surface of the reflection partition plate 2b
as the heat recovery air supply means (:Ln Fig. 2B, only one
row of such tubes are shown). ~ multiplicity Oe air disper-
sion port:Lons 8a' are drilled :Ln the surface of the air
dispersion tube 8b on the side facing the reflection parti-
tion plate 2b. The lower end of the air dispersion tube 8b
is connected to the heat recovery air supply tube 9 which
extends from the heat recovery air supply source. A control
valve 9a and the flow meter 7b are inserted inside the air
supply tube 9 in series with the former closer to the heat
recovery air supply source. A heat recovery tube 1~ which
is incorporated in the heat recovery means is arranged above
the air dispersion tube 8b in the heat recovery chamber 4.
One end of the heat recovery tube 10 is connected directly
to the boiler drum 17 and the other end is connected to the
; boiler drum via the circulation purnp 11.
The incineration chamber 3 and the heat recovery
chamber 4 are both filled with a fluidizing medium such as
particles of quartz (havin~ a particle size of about 1 mm)
or the like. The fluidizing medium in the incineration
chamber 3 is allowed to enter the heat recovery chamber 4
over the upper end portion of the respective reflection
partition plates 2b while the fluidizing medium in the heat
recovery chamber 4 returns to the incineration chamber 3
below the respective reflection partition plates 2b in the
2(~11 g[)3 ~r 1~ ~3
heat recovery chamber 4, the fluidi~ing medium thus belng
capable of circuLating in both chambers.
A means 14 ~or supplylng combustibles are provided at
the opening (not shown) provided in communication with the
incineration chamber 3. A screw-type f'eeder 13 (see Fig. 5A)
driven by a motor 12 is incorporated in this com'bustible
supply means.
The boiler drum 17 ~its in the wall 1 o-f the boiler C
at the upper portion thereof in such a manner as to be
surrounded by a heat receiving water pipe 16 having a -elue
opening 16a at one portion thereo-f' and capable Oe receiving
heat -from the inc:Lneratlon charnber 3. The bo:Ller drum 17 ls
provided with an upper s-team drum 17a and a lower water drum
17c which are connected by means of a multiplicity of
convective tubes 17b.
A water supply pipe 19 is provided extending erom the
water source to the steam drwn 17a. Provided in a s-team
pipe 20 extending Prom the steam drum 17a -to a s-team load 21
via a steam separator 17d are a -flow meter 20a serv:Lng as a
means for detecting steam flow rate and a pressure gauge 20b
serving as a means -for detecting steam pressure. Re-ference
numeral 22 designates an exhaust port for combustion gas
embedded in the wall 1 of the boiler adjacent to the boiler
drum 17.
~ control apparatus B is provided as a separate uni-t
adjacent to the boiler C which it controls in accordance
with the present invention. The control apparat-us B is
supplied with output signals which pass through signal lines
from the temperature sensor 3a, the flow meters 7b, gb and
20 and the pressure gauge 20b. Output signals -from the
control apparatus B are supplied through signal lines to the
control valves 7a, 9a and the combustion supply means 14.
A general explanation o-f -the operation o-f the boilers
A and C shown in Figs. 2A and 2B and controlled by the
incineration control apparatus according to the present
invention will now be given.
The fluidizing medium in the incineration chamber 3
is blown upwardly by incineration air having an adequate air
--'' Z00313~3
-15-
velocity (a mass veloc:Lty o-f more than about 2 Gmf') which ls
supplieA into the air chamber 6 through the incineratlon air
pipe 7 and in,3ected upwardly ln the lncineratlon chamber 3
Prom the alr supply ports 5a of the alr supply plate 6, thus
formlng a -~luldized layer to become a fluld bed.
A part Or the -fluld bed ln the inclneratlon chamber 3
is caused to flow -from the splashing surface of -the -fluid
bed and a portion of the -fluid:Lzing medium which Jumps over
the upper end portion 2a of the part:Ltion plate 2 is caused
to swirl into the heat recovery chamber 4. The same quan-
tity o-f -fluidizlng mediu~n, i.e. corresponding to -the amount
o-f'-fluidizing medium thus entering the heat recovery chamber
4, is caused to return to the incineration chamber 3, there-
by creating a circulating flow. The quantity o-f fluidizing
medium which may flow into the hea-t recovery chamber 4 -from
the incineration chamber 3 can be controlled in accordance
with the air veloc:ity of the incineration air (or the mass
velocity).
Fig. 3A illustrates an example of the relationship
between the air velocity of the incineration air (the mass
velocity) and the amount o~ fluidlzing medlum which -flows
lnto the heat recovery chamber from the lnclneration
chamber. According to this graph shown ln Fig. ~, when the
alr veloclty varies ln the range of from 4 ~m-f' to 8 Gm-f, the
amount o-f circulating fluidizing medlum may be controlled to
not exceed a value o-~ ten times in the approximate range o-f
from ~.l to 1.
Fig. 3B illustrates an example o-f the relationship
between the air velocity of the heat recovery air (or the
mass velocity) and the descending speed of the fluidizing
medium in the moving bed in the heat recovery chamber 4,
or the amount of fluidizing medium which may be returned to
the incineration chamber 3 from the heat recovery chamber 4.
According to -this relationship. the amount of circulating
fluidizing medium which is determlned -from the amount o-f
fluidizing medium to be returned to the incineration chamber
may be expressed by the relationship (or operational curve)
wlth the amount of fluldlzing medlum whlch -flows into the
2C)~)3~
-16-
heat recovery charnber (or the parallleter shown in ~ig. 3B).
The extent of circulat:Lon varies depend:Lng on the combust,ion
air velocity and Lncreases linearly ~or each amount of
flu:Ldizing medium that overflows :from the incineration
chamber to the heat recovery chamber. I-f the a~lount -for the
circulation of f'luidizing medium -~lowlng -from the incinera-
tion chamber is speci-fied, this amount o-f -~luidizin~ medium
may increase or decrease substantially proportionally to the
air velocity for heat recovery expresscd by the ~bsclssa
along the corresponding operational curve in the rarlge o~
0 to 1 G~f o-f the air velocity -for incineration.
Accordingly when the air velocity of the lncineration
air is constant, the amount Oe circula-ting fluldizlng med:Lwn
may be controlled in accordance with the a:Lr veloc:Lty of the
air for heat recovery. When the a:Lr velvcity o-f the incin-
eration air Ls not cons-tant, ~lowever, the amount of circu-
la-ting -fluldizing medium may be controlled in accor-dance
with the air velocity o-~ both the air for heat recovery and
the air -~or incineration.
CombLIstibles such as coal or the like, or waste such
as municipa:L re-fuse or the like are charged onto the fluid
bed in the :Lncineration chamber 3 for incineration there and
keep the -fluid bed at a high temperature in the order of
800~C - 900~C. As a result, the boiler drum 17 receives the
heat generated by thls high temperature and converts the
water supplied to the boiler drum 17 via the water supply
pipe 19 into steam in the steam drum 17a. Then, after water
has been removed by the steam water separator 17d, -the steam
will be supplied to the steam load 21 via the steam pipe 20.
The operation of boiler of the type explained above is well
known in itself.
On the other hand, the ~luidizing medium in the heat
recovery chamber 4 will -form a moving bed which gradually
descends in an orderly fashion in the downward direction as
a solid substance in response to injection of the air for
heat recovery, the air velocity of' which is relatively slow
-~rom the dispersion ports 8a of the air dispersion plate 8
in the heat recovery chamber. This moving bed will remain
ZC)(~313~
:Ln contact w:Lth the heat recovery tube 10 SUC}I as to direct
the heat in the moving bed into -the water :Ln the heat recov-
ery tube 10 by means of heat transrer. Conseqllently, the
heated water in the heat recovery tube 10 will be ~orced
into the steam drum 17a by me~ns o-P the circulation pu~p 11.
In this way. the heat in the -f~Luidi~ing medium in the heat
recovery chamber 4 or the heat in the fluid bed in the
incineration chamber 3 will be recovered by and transferred
to the boiler drum 17. In this way, the heat in the -rluid-
i~in~ med:lum contained in the heat recovery chamber ~ andthe heat in the fluid bed in the lnclnerat:lon chamber 3 wll]
be trans-eerred to the boller drum. However, :Lt is to be
noted that the amount of thermal energy recovered may be
controlled in accordance wlth -the a:lr velocity (or the mass
velocity) of the air for heat recovery which is in-to the
heat recovery chamber 4 through -the air dispersion plate 8.
More specifically, Fig. 4 illustrates in solid lines an
example Oe the relationship between the velocity (or the
mass velocity) of the heat recovery air and the heat trans-
fer coe-fficient ~ o~ the heat recovery tube 10 in the moving
bed. According to this graph, when the air velocity o-~ the
heat recovery air is varied in the range -~rom 0 Gm-~ to 2 Gm~,
the heat transfer coefficient ~ may be controlled substan-
tially linearly with a relatively large gradient (or gain)
compared to that o~ the fluidized bed or the fixed bed.
In the same graph, the dotted line indicates exa~ples
o~ the heat trans-~er coe-fficient which will vary depending
on the air velocity, the indicated heat trans-fer
coe-fficients bein~ those which would normally be a-ttained
in a -~ixed bed at an air velocity of less than 1 Gmf and
in a fluidi~ed bed at an air velocity o-f more than 2 Gmf,
respectively, these being shown in comparison with those
attained in a moving bed (indicated by the solid line). As
~his graph shows, the variation in the heat trans-~er co-
efficients resulting from changes in the air veloc:Lty isslight (or the gradient is extremely gentle), and although
any variation in the heat transfer coe-~ficient in accordance
with air velocity will become quite considerable in the
2~03~
-18-
transLt:Lonal area between the eixed bed and the flll:Ldized
bed, the range o~ air velocity corresponding to this transi-
t:Lonal area is so small that control of the heat transfer
coef-ficient at the -fixed bed, -fluidized bed or the transi-
tional area is not of any practical sLgnificance.
Since operation of the bo:Ller C shown in Fig. 2e is
identical to that o-f the boiler ~ which has already been
explained, an explanation Oe it will no-t be given here.
As described above, the technica:L means of varying
the velocity of the heat recovery air ln the therrnal energy
recovery chamber is, as compared w:Lth the conventLonal
stepwise intermittently controLled heat recovery in which
the bed condition of the fluidizing medium in the thermal
energy recovery chamber Ls varied only between a fluidized
bed condition having an extremely high heat transfer
coe-f-f:Lcient and a -fixed bed condition having an ex-tremely
low heat transfer coe-f-ficient, capab]e Oe controlling the
heat trans-fer coef-ficient steplessly and linearly and over a
wide range. Further, since the technical means o-E varying
the velocity o-f the heat recovery air in the thermal energy
recovery chamber is, as shown in ~ig. 3B, capable o-f
controlling the amount of the circulating fluidizing medium,
-fine control over a wide range is made possible by -these
technical means as a multiplied ef-fect o-f the control of the
heat trans-fer coefficient and the control of the amount o-f
the circulating fluidizing medium. Therefore, coupled with
the technical idea that the amount o-f the heat recovery air
supplied to the -thermal ener~y recovery chamber is
determined by the steam pressure dependent heat recovery air
supply control means and can be rapidly increased or
decreased, the present invention provides an operational
effect that the variation of the steam pressure in the
boiler drum due to variation of the steam load can be more
precisely and rapidly controlled than in the conventional
apparatuses.
The concrete constitution and operation O:e an
incineration control apparatus B according to the present
invention will now be explained. It is to be noted that the
20n~38~B
-19-
snme re:~erence numerals and ref'erence symbols are used in
the following explanation -to desigrlate components whl.ch are
the same as those already referred to :Ln the descrlption o-f.
Figs. 5A and 5~ illustrate the first embod:Lment O-e
the incineration control apparatus according to the present
invention as applied to the boilers A and C. The outpu-t
terminal o-f the pressure gauge 20b contained in the steam
pipe 20 is connected to a termi.nal for inputting input
signal PV01 to the pressure controller 31 which serves as
means for controlling the amount of combustib:Les supplied
and a terminal for inpwtting the set pressure value SV01
-to the pressure controller 31 :Ls in turn connected to the
so-urce of relevant set pressure va:Lue signals. The term:Lnal
for the operational output signal MV01 erom the pressure
controller 31 is connected to the input terminal of a signal
inver-ter 32 which serves as a means for controlling the set
temperature value as well as to a mo-tor 12 incorporated in
the combustion supply means 14 at an intermediate position
toward the branch to the signal inverter.
The output O-e the signal inverter 32 i9 connected to
the terminal for the set temperature value input signal SV02
to a temperature controller 33, and the temperature sensor
3a that serves as a means for detecting the temperature in
the incineration chamber 3 is connected to the terminal for
inputting the input signal SV02 to the temperature control~
ler 33. The terminal for the operational output signal MV02
from the temperature controller 33 is connected to the
termi.nal for inputting the set flow rate value input signal
SV03 to a flow rate cont,roller 34.
The terminal for the operational output signal MV03
from the flow rate controller 34 is connected to the control
terminal of the control valve 9a contained in the heat
recovery air pipe 9 and the terminal for inputting the input
signal PV03 to the flow rate controller 34 is connected to
the output terminal of the flow meter 9b contained in the
air pipe 9. The temperature controller 33, flow controller
34, control valve 9a and flow meter 9b contained in the
air pipe 9 together constitute a means for controlling
~0(~3~
~20-
the air supply Por heat recovery. In addition, they also
const:Ltute, together with the combustibles supply contro:L
means 31 an~ the set temperature value control means 32,
means -for controll:Lng air supply -for heat recovery in
accordance with steam pressure.
Opera-tion o-~ the :lncineration control apparatus shown
in Figs. 5A and 5B will next be explained. ~s the steam
load increases, the steam pressure detected by the pressure
gauge 20b in the steam pipe 20 will be reduced, and the
signal PV01 inpu-t to the pressure controller 31 will thus be
reduced too. Then, s:Lnce the input signal PV01 w:il] beco~ne
smaller relative to the pressure se-t value signal SV0:L which
is set at a constant value, the operational output signal
MV01 -from -the pressure controller 31 shows a tendency to
rise, -thereby increasing the rotational speed o-f the motor
12 in the combustion supply means 14. In 1;his way, the
operational speed of a screw type -feeder 13 will be increas-
ed in order to increase the amount o-P combustibles supplied,
whereby incineration in the incineration chamber can be made
more active. Thus, the temperature o~ the -~luidized bed in
the incineration chamber 3 will be raised in the long run
and, as a result, the amount o-f heat received by the boiler
drum -from the incineration chamber 3 will also increase, so
that the steam pressure in the boiler drum 17 w:Lll gradually
increase and return to its previous level.
While the above-mentioned operation is ta~ing place,
in the short term the signal inverter 32 will respond to the
operational output signal MV01 from the pressure controller
31 and supply the output signals thereof to the temperature
controller 33 as the set temperature value signal SV02 -for
the temperature controller, thereby enabling changes in the
set temperature value. More specifically, the signal
inverter 32 has input/output characteristics such as those
shown in Fig. 6, so it will receive as an input signal the
operational output signal MV01 -from the pressure controller
31 which varies in the range o-~ from 0% to 100%, and will
output the temperature set value signal SV02 corresponding
to a temperature in the range O-r -from 800~C to 850~C to the
20(:)38~3
-21-
temperature con-troller 33. S:Lnce the operational outpu-t
signal MV01 has a tendency to increase :Ln the example o-
~operation explained, -the point at wh:Lch the signal inverter
will be activated will shift in the direction indicated by
the arrow in Fig. 6, and the set temperature value signaL
SV02 supplied to the temperature controller will thus change
to a lower value. It should be understood here that the
varlation range o-f the set temperature value signal SV02
corresponding to the variation range of 0% tc 100% -eor the
operational output sigllal ~V01 has been selected as 800~C -
850~C based on the knowledge tha-t operation o-f the -fluidlzed
bed in the temperature range is preferable -froln varlous
points of view, such as better lnc:Lnera-tion e-f-f:Lc:Lency,
prevention o-f sLntering of the :OEluidized bed, be-tter desul-
-furi~ation ef-ficiency (in -the case O-e coal burning), preven-
tion o-f carbon monox:Lde generation (in the case of coaL
burning) and so forth.
When the set temperature value signal SV02 in the
temperature controller 33 is reduced, then the input signal
PV02 from the temperature sensor 3a and -the set temperature
value signal SV02 in the temperature controller 33 do not
match, so the temperature controller 33 will be caused to
operate to reduce this d:Lf-ference by increasing the opera-
tional output signal MV02.
Then, since larger set flow values have been
established at the -flow controller 34 which receives the
increased operational output signal MV02 as the set -flow
rate value signal SV03, the operational output signal MV03
will be increased so as to match the input signal PV03 from
the -flow meter 9b with the newly established set value.
Thus the opening degree of the control valve 9a will be
increased and the velocity of the heat recovery air which
is fed to the air dispersion plate 8 via the heat recovery
air pipe 9 and then Jets into the heat recovery chamber 4
will be increased.
Consequently as clearly seen -from the graph sho~n in
Fig. 4 already explained, the heat transfer coe~-ficient o-f
the moving bed in the heat recovery chamber 4 will also have
~0038~3
-22-
a tendency to :lncrease :ln accordance w:l-th the tendency of
the velocity o~ the heat recovery air and the amount of
thermal energy trans-~erred to the boiler drum 17 from the
heat recovery chamber 4 through the heat recovery tube 10
will also be increased.
Increasing the amount o-~ thermal energy in accordance
with the veloc:Lty of the heat recovery air as above
explained may enable the steam pressure to be increased and
restored to its previous ]evel eor a short period of time in
such a manner as to discharge hea-t accumulated in the moving
bed in the heat recovery chamber 4 to the heat recovery tube
10. Eowever, this only occurs momentarily before the steam
pressure increases in accordance with the amount of combus-
tibles supplied, whlch takes a :Longer tlme, as already
explained.
When the steam pressure has been raised and re-turns
to its previous level, the input signal PV01 to the the
pressure controller 31 from the pressure gauge 20b will also
exhibit a tendency to increase. Since the pressure control-
ler 31 will be balanced at the point where the input signalPV01 has increased to match the predetermined set pressure
value signal SV01, the operational output signal MV01 f'rom
the pressure controller 31 will become settled at the medlan
point (50%). Correspondingly, the amount O-r combustibles to
be supplied to the combustibles supply means 14 will also be
reset to the median (50%) and at this time, in correlation
; therewith, the air velocity of the heat recovery air at the
air dispersion plate in the heat recovery chamber 4 will
also be returned close to the median (50%). The operation
explained above is exercised as a response of the system to
any external disturbance due to a reduction in steam pres-
sure. The operation ~ill of course be reversed in response
to any external disturbance due to an increase in steam
pressure.
In summary, the incineration control apparatus
according to the present invention is applied to a fluidized
bed type boiler having an incineration chamber 3 filled with
fluidizing medium and adapted to incinerate combustibles
~o~
-23-
and a heat recovery chamber ~ locate~ adJacent to the
incineration chamber and de~'ined :Ln such a manner as to
enable the fluidizirlg med:Lum :Ln -the incineration chamber
to be circulated thereto and capable of recovering the heat
in the -fluidizing medium in the hea-t recovery chamber and
trans-ferring it to the boiler d:rum 17 through the heat
recovery means 10 and 11 provided :Ln the heat recovery
chamber in accordance with the amount o:f heat recovery air
supplied in the heat recovery chamber 4 from the heat recov-
ery air supply means 6a, 8, 8a, 8a' and 8b provided :Ln the
hea-t recovery chamber, the inci:neration control appara-tus
being so constructed that the control means 31, 32, 33, 34,
9, 9a and 9b -~or controlling -the amount of heat recovery air
supplied in accordance with the steam pressure con-tro:Ls the
amount o-f air (or the air velocity) to be supplied into -the
heat recovery chamber 4 in accordance wlth the steam pres-
sure in response to the steam pressure signal PVOl -~rom the
pressure gauge 20b which serves as the means -ror detecting
the steam pressure. In this manner, the amount of thermal
energy trans~erred to the boiler drum 17 ~rom the heat
recovery chamber 4 may be controlled in accordance with the
steam pressure. Typically, the amount o-f combusti.bles
supplied may be controlled in accordance with the steam
pressure in such a way that the pressure controller 31
servin~ as the control means ~or controlling the amount of
combustibles supplied will provide the operational output
signal MVOl to the combustibles supply means 14 so that
the steam pressure signal PVOl ~rom the pressure gauge 20b
servlng as the steam pressure detecting means may be
balanced relative to the set pressure value signal SVOl.
On the other hand, the temperature controller 33 serving as
the heat recovery air supply control means 33, 34, 9, 9a, 9b
will supply the operational output signal MV02 to the flow
controller 3~ as the set value signal SV03 so that the
tempera-ture signal PV02 ~rom the temperature detecting means
3a may be balanced rela-tive to the set temperature value
signal SV02. The flow controll.er 34 supplies the opera-
tional output signal MVo3 to the control value 9a so that
3~3
-2~-
the (a:ir) flow s:Lgna:l PV()3 Prom the f:Low meter 9b may be
balanced relative to the set va].ue s:Lgnal SV03, varies the
amoun-t (air velocity) of a:Lr supplied into the heat recovery
chamber 4 and controls the anlount of thermal energy trans-
-ferred to the boiler drum 17 Prom tlle heat recovery chamber
4 in accordance with the temperature. Two kinds o-f con-trol
operations as above explained may be interrelated by corre-
lating the operational output signal MV01 -from the pressure
controller 31 with the set value signal SV02 suppl:Led to the
temperature controller 33 by the signal inver-ter 32 as t~e
set temperature contro.L means. In this way, while a control
operation serving -to execute long term control is executed
by the pressure controller 31 acting as the combust:Lbles
supply contro:L means to constantly secure the correct amoun-t
o-f combustibles irrespect:lve of :Lncreases or decreases in
the steam pressure caused by variations in -the steam load,
the amount (or air velocity) of heat recovery air suppl:ied
:Lnto the heat recovery chamber 4 may be increased or
decreased ~or a shor-t period o-f time in accordance with the
steam pressure, so that -the heat accumulated in the -fluidiz-
ing medium in the heat recovery chamber ~ may be trans-ferred
to -the boiler drum 17 in such a manner ns to be discharged
momentarily, or heat supply to the boiler drum 17 may be
restricted in such a manner as to accumulate heat momen-
tarily in the -fluidizing medium. Thus the operation oP
controlling the steam pressure may be rapidly executed
whenever there is a variation in the steam load.
It is to be noted, however, that in the incineration
control apparatuses shown in Figs. 5A and 5B, since the
amount of combustibles to be supplied is controlled solely
on the basis oP steam pressure, when it is necessary to
constantly control the amount of combustibles supplied in
the -Pace of variations in the steam load or steam pressure
over a long period of time, it becomes necessary to
constantly adJust the amount of combustibles supplied by
the combustibles supply means 14 which involves nlaking the
control of the steam pressure at the pressure controller 31
out of balance. As a result, with regard to the control of
~o~
-25-
the steam pressure on the basis of -the veloci-ty of the heat
recovery air through cooperation between the temperature
controller 33 and the -flow controller 34, it has to be
taken into consideration that keeping the air velocity Oe
the heat recovery air near the median (or 50%) in the -~ace
of external disturbances will become impossible and that it
will be di-~flcult to uniformly achieve maximi~at:Lon o-f the
amount of thermal energy recovered and trans-ferred to the
boiler drum 17 which may :lnvolve both increases and
decreases o-f such amount.
F'igs. 7A and 7B illustrate a second embodiment o-f
an incineration control apparatus according to the present
invention which can be appl:Led respec-tively to the boi.Ler A
shown in Fig. 2A and the boiler C shown in ~ig. 2B.
In Fig. 7A, an output terminal of a flow meter 20a
contained in a steam pipe 20 is connected to one of the
input terminals o-f a computing eLement 35 which serves as a
means -for control:Ling the amount of combustibles supplied on
the basis o-~ a steam load, while the other input terminal of
the computing element 35 is connected to a terminal -for the
operational output signal MV01 -from a pressure controller
31. An output terminal o-f the computing element 35 is
connected to a motor 12 o-f a combustibles supply means 14.
The remaining constitution is identical to that of the first
embodiment shown in Figs. 5A and 5B.
Operation o-f the incineration control apparatus shown
in Fig. 7A will now be explained. As the steam load is
increased, the steam pressure which is detected by the
pressure gauge 20b will decrease and the opera-tional output
signal MVOl -from the pressure controller 31 will thus have a
tendency to increase. This is the same as the case of the
first embodiment (shown in Figs. 5A and 5B). However, the
operational output signal MV01 is not provided directly to
the motor 12 o-f the combustibles supply means 14 like in the
first embodiment, but is instead supplied to the other input
terminal o-f the computing element 35.
During this time, since an output signal -~rom the
-flow meter 20a contained iIl the steam pipe 20 i5 supplied
2~
-2~-
as an input signal PV04 ind:Lcating -that the stea~ -elow rate
has a tendency to increase, the computing element 35 w:ill
calculate the arithmetic output signal YO expressed ln the
-~ollowing equation in accordance with the input signal PV04
and the operational output signal MV01 and supply them to
the motor 12.
Y0 = PV04 ~ a(2MV01 -- 100)
wherein "a" = a constant value, thus determlning the varia-
tion range of the arithmetic output signal Y0.
An explanation will now be glven regarding how -the
arithmetic output signa:L Y0 is determined by the signa:L PV04
and ~V01 provLded by the ~'Low meter 20a and the pressure
contro]ler 31, referring to Figs. 8 and 9.
Fig. 8 is a graph show:ing the relationsh:Lp between
the operational output signal MV01 supplied to the other
input terminal of the computing element 35 and the arith-
metic output signal Y0 -from the computing element. The
operation point Pl which represents a normal condition
wherein the operational output signal MV01 from the pressure
controller 31 is settled at 50% is located on the character-
istic curve shown by the solid line, and the arithmetic
output signal Y0 on the abscis~a corresponding to the
point Pl may thus be defined. As is clear -from the above-
mentioned equation, the arithmetic output signal Y0 is also
governed by the input signal PV04 supplied to one o~ the
input terminals of the computing element 35.
Fig. 9 is a graph showing the relationship between
the steam flow rate (PV04) detected by the ~low meter 20a
and the amount of combustibles supplied (%~ or the arith-
metic output signal Y0 supplied to the combustibles supplymeans 14, -from the computing element 35. Since this
relationship is included in the input and output character-
istics of the computing element 35 as being governed by the
input signal PV04~ if the steam -~low rate (PV04) is Ql at a
normal condition, i.e. at 50%, the operation point ql is
located on the characteristic curve and the arithmetic
output signal YOl on the abscissa corresponding to the
operation point may be defined. It will be understood
2~
-27-
that the arithmetlc ou-tput sLgnal YOl co:Lncides with the
arithmetic output s:ignal YOl corresponcling -to the operat-lon
point Pl on the characteristic line inclicated by -the solid
line in F:Lg. 8.
When the steam load increases and the steam flow ra-te
(PVOA) is increased in stepwise fashion from Ql to Q2, then
the operation point is sh:ifted -from ql to q2 on -the charac-
teristic line in Fig. 9. Accor-dingly, since the value of
the arithmetic output signal YO increases in stepwise
fashion -from YOl to Y02, -the characteristic line drawn as a
solid line in Fig. ~ will be shifted upwardly and rightward-
ly in the drawing to the position of the characteristic lLne
drawn as a dotted l:Lne and consequently the operat:Lon point
Pl w:Lll be immed:Lately shifted to the operation point P2.
Since the steam pressure will respond to increases
in the steam flow rate (YV04) accompanied by an increase in
the steam load in an integral manner, the steam pressure
will drop temporarily and the input signal PVOL ~rom the
pressure gauge 20b to the pressure controller 31 will also
be reduced. In response -to -this reduction, the operational
output signal MVOl from the pressure controller 31 will be
gradually increased and the operation point P2 on the
characteristic line drawn as a dotted line in Fig. 8 will
also be raised along the charac-teristic line to the opera-
tion point P'2 for example. Accordingly, the arithmeticoutput signal YO on the abscissa in Fig. B will be gradually
increased to the point Y02'.
Subsequently, in response to the gradual increase in
the arithmetic output signal YO, the speed of the motor 12
will increase and the amoun-t o-f combustibles supplied by the
combustibles supply means 14 will also be increased, whereby
incineration in the incineration chamber 3 will become
active and an increased amount of evaporation will be
generated in the boiler drum 17. This will in turn cause
the steam pressure to gradually rise and, in the long run,
the operational output signal MVOl from the pressure
controller 31 will be forced up to the value O-r 50% at the
~20~3~
-28-
time where the pressure control:Ler 31 :Ls in a balanced
condition and will settle at that value.
During -this operation, the cooperation O-e the
signal inverter 32, which respon~s concurrently -to gradual
increases in the arithmetic output signal YO by causin~ an
increase in the operatlonal output signal MV01, with the
temperature controller 33 and the flow controller 34 will
control the amount o-f thermal energy transferred to the
boiler drum 17 from the heat recovery chamber 4, as already
explalned, whereby the balancing operat:Lon conducted by the
pressure controller 31 will be tac:Llitated.
Accordingly the operation point P2' which has once
been raised along the character:Lstic curve drawn as a dotted
line in Fig~ 8 wil:l be forced downward:Ly to settle at -the
operation point P2. The arithmetic output signal YO corre-
sponding to the operation point P2 will at this t:Lme settle
at -the value YO2 to secure the operation point q2 corre-
sponding to the steam -flow rate Q2 which is constantly
increasing along the characteristic line shown in Fig. ~.
Thus, when the amount o-f combustibles supplied by the
combustibles supply means 14 is increased or decreased by
the constant changing of the value of the arithmetic output
signal YO from the computing element 35 in response to the
constant variations in the steam load, the operational
output signal MV01 from the pressure controller 31 may be
constantly forced down to the value of 50%.
This will enable the variable amount o-f thermal
energy recovered and transferred to the boiler drum 17 from
the heat recovery chamber 4 to be maximized uni-formly
whether increases or decreases in this amount are taking
place since the velocity of the heat recovery air is kept
constantly at the median point thereo-f within controllable
range with the steam pressure in a normal condition. This
is possible because the steam pressure is rapidly restored
to the previous level when an increase or decrease occurs,
this being achieved by causing an instantaneous increase or
reduction in the amount of thermal energy in accordance with
~6~03~
-29-
the velocity Or -the heat recovery alr throu~h the coopera-
tlon Oe the signal inverter 32, the temperature control:Ler
33 and the -rlow controller 34, which operate in the same
manner as in the first embodiment (illustrated in Figs. 5A
and 5B).
The second embodiment of the lncinera-tion control
apparatus according to the present invention as app]ied to
the boiler A shown in Fig. 2A has been explained with refer-
ence to ~ig. 7A. Since application oE the control apparatus
to the boiler C shown in Fig. 2B is similar to the above
application, explanatlon o-~ the incineratlon con-trol appa-
ratus shown in Fig. 7B :Ls ornitted here.
In summary, according -to the second embodiment of
the incineration control apparatus according to the present
invent:Lon, the computing element 35 which serves as the
combustibles supply control means -for controlling the amount
of combustibles supplied on the basis o-f steam load computes
and generates the arithmetic output signal YO required -ror
securing constant adJustment o~ the amoun-t of combustibles
supplied in correspondence with the constant variations in
the steam load which depend on the steam flow rate when
supplied with the operational output signal MV01 (50%) from
the pressure controller 31 which serves as the combustibles
supply control means during the time when the system is in a
balanced condition, this signal then being output to the
combustibles supply means 14. This will cause the pressure
controller 31 to be kept constantly balanced in the normal
condition regardless of the prevailing steam load or the
amount of combustibles supplied, keep the operational output
signal ~V01 at the value of 50%, bring the amount of heat
recovery air supplied (or the air velocity) close to the
median of 50% at the heat recovery air supply control means
33, 34, 9, 9a and 9b which respond to the operational output
signal MV01, and thus uniformly maximize the range O-r varia-
tion in the amount of heat recovery air supplied whether theamount thereof is increasing or decreasing.
According to the second embodiment of the incinera-
tion control apparatus of the present invention, i-r there is
Z(~03~3
-30-
a constan-t amoun-t of the flu:ldiz:Lng medium which -flows from
the inc:Lneration chamber 3 to the heat recovery chamber 4
(the constant amount being determined by the incineration
air velocity which is -fixedly set), -this will cause the heat
accumulated in the -fluidizinK medium contained :Ln the moving
bed in the heat recovery chamber to be discharged momentar-
ily so as to be trans-ferred to the bo:L:Ler drum 17. Ilowever,
the amount of -fluidizing medium which may be diverted -from
the inc:ineration chamber 3 to the heat recovery chamber 4 is
not controlled at all. Accordingly, the amount o-f thermal
energy may be advantageously lncreased or decreased due to
a variat:Lon in the velocity of the heat recovery air when
there is a balanced condi-tion a-t each of the heat recovery
air supply control means 33, 34, 9, 9a and 9b. ~lowever,
since the thermal energy accumulated in -the flu:Ldizing
medium contained in the moving bed in the heat recovery
chamber 3 i9 not fully controlled, when the skeam pressure
is restored to the normal condi-tion -following an external
disturbance which causes an increase in pressure, the amount
of thermal energy accumulated in the heat recovery chamber 4
will be so little that there may be di-f-ficulty in momentar-
ily restoring the steam pressure.
Figs. lOA and lOB illustrate the constitution o-f
a third embodiment of the incineration control apparatus
according to the present invention which is applied to the
boiler A shown in Fig. 2A and the boiler C shown in Fig. 2B.
The dif-ference between the third embodiment and the second
embodiment shown in Flgs. 7A and 7B resides in that the
signal line connected from the output termina] o-f the
computing element 35 to the motor 12 incorporated in the
combustibles supply means 14 is also branched at a point
along it before it reaches the motor, this branch leading
to the terminal for the -flow set value signal SV05 -for the
incineration air supply -flow controller 36.
In the incineration air supply pipe 7 ex-tending to
the air chamber 6 from a incineration air source not shown
in the drawing, there are a control valve 37 and a flow
meter 38 provided in that order toward an air chamber 6.
3~
-31-
The terminal for a operat:Lon output s:lg~a:l MV05 of a inc:Ln~
eratLon a:Lr flow controller 36 ls connected to the control
termlnal of a control valve 37 ancl the output termLnal of
the flow meter 38 is connected to the terminal for a input
signal PV05 o-f the -flow controller 36. The -flow controller
36, the control valve 37 in the incineration air pipe 7 and
the flow meter 38 in the air pipe constitute a incineration
air supply control means.
According to the constitu-tion as explained above, at
the time of momentary increase or decrease of the stealrl
load, as the steam -flow rate detected by the -f]ow meter ZOa
increases or decreases, -the input signal PV04 to the comput-
ing element 35 will be increased or decreased and in re-
sponse there-to the computing element w:Lll shi~t momentari:ly
the operation po:Lnt on the characteristic curve shown in
Fig. 8 upwardly elther le-ftwardly or rightwardly so as to
instantaneously increase or decrease the arithmetic output
signal YO from the computing element 35. This will ensure
momentary restoration o-f the steam pressure. On the other
hand, if the steam pressure detected by the pressure gauge
20b depending on the normal change o-f the steam load is
increased or decreased in a normal manner, the computing
element 35 will vary the position o-f stable operation at
the time of balanced condition o-f the pressure controller 31
depending on the amount of the steam flow and provide to the
electric motor 12 normal arithmetic outpu-t signal YO corre-
sponding to the increased or decreased steam load. This
will ensure a control operation for the steam pressure for a
long period of time. Since such output signal YO from the
computing element 35 is also suppl:ied to the incineration
air supply -flow controller 36 as a flow rate set value
signal SV05, supposing that the steam load is increased so
that the amount of combustibles supplied by the combustibles
supply means 14 will show a sign o-f increase, the flow rate
set value signal SV05 which is the output signal from the
computing element 35 will also show a sign o-f increase.
Consequently since the inp~lt signal PV05 will not coincide
with the -flow rate set value signal SV05 at the -flow
20038~3
-32-
controller 3~, the ~].ow rate control:ler 36 wi:l:L increase
the opcrational output signal MV05 and increase opening
degree o e the control valve 37.
As a result, when the steam load is normally
increased and the amount o-f the supplied combustible is also
increased normally, then the opening degree of the control
valve 37 is also normally increased, so that the velocity o-f
the incineration air which is inJected into the incineration
chamber 3 from the air chamber 6 through the incineration
air pipe 7 will also be increased. According to the opera-
tion point on the operational curve as explained with refer-
ence to Fig. 3A will be shifted :ln the direction indicated
by the arrow shown in Flg. 3A and the amount of the -fluidiz-
ing medium which :Elows from the incineration chamber 3 to
the heat recovery chamber 4 will be increased, so that the
parameter (or -the amount of circu]ation of the -fluidizing
medium) in the operation curves illustrated in Fig. 3B as
explained already will correspondingly be increased and the
operational curves o-f the operation in question will be
moved in the direction indicated by the arrow.
Therefore, the amount o-f the -fluidizing medium flow-
ing from the heat recovery chamber 4 to the incineration
chamber 3 or the amount o-f circulation of the fluidizing
medium will be increased and such -fluidizing medium will be
carried to the fluidizing medium contained in the moving bed
in the heat recovery chamber 4, ca-using the thermal energy
accumulated in the moving bed to be increased and restr:ict-
ing reduction of the temperature o-f the moving bed varying
depending on the recovery thermal energy to keep the temper-
ature at a high level.
Since the heating value R recovered into the boilerdrum 17 from the heat recovery chamber 4 is expressed by the
equation:
R = A*~*~T
where A = the ef-fective heat receiving area o-f the heat
recovery tube lO
~ = coefficient of heat transfer
;.
382~
-33-
~ T = dle-ference in temperature betw~en the -~luidl~lng
medlum in the movlng bed ln the heat recovery chamber 4 and
the s-team ln the boller drum 17,
main-tenance at a high level of the temperature o-f the -~lu:Ld-
izing medium in the moving bed in the heat recovery chamber
4 means that more thermal energy may be recovered. Thus
even if the steam load is usually excessive su-f:eicient
recovery of the thermal energy into the boiler drum -Prom
the heat recovery chamber 4 may ensure a quick restoration
0 o-f the steam pressure.
As clearly seen -erom the eoregoing explanation, ln
the third embodiment o-f the incineration control apparatus
according to the present inven-tion, the incineration air
supply control mearls 7, 36, 37 and 38 will respond to the
continuously increasing arithmetic output signal YO supplied
-from -the computing e]ement 35 lncluded in the means -for
controlling the amount o-f combustible supplied depending on
the steam load when the steam load is increasing in a normal
manner, increase the amount of the incineration air supply
(or the velocity of air ~or incineration) into the incinera-
tion chamber 3, increase the amount o-f' the -fluidizing medium
circulating in the heat recovery chamber 4 and increase the
thermal energy carried -from the incineration chamber 3 and
stored in the -fluidizing medium. This will ensure su-ffi-
cient amount of the thermal energy recovered into the boilerdrum 17 from the heat recovery chamber 4 even i-f the steam
load is normally excessive, whereby upward restoration o*
the steam pressure due to insu-fficient thermal energy
recovered may be prevented from being delayed.
POSSIBILITY OF INDUSTRIAL UTILIZATION:
According to the present invention, since the steam
pressure in the boiler drum is correlated to control of
the thermal energy recovered into the boiler drum, so that
response of control of the steam pressure against variation
caused by variation of the steam load is enhanced, the
present invention may be applied to the control means in a
20~)38~
-34-
-Pluid:Lzed bed type boiler adapted to inc:Lnerate such combus-
t:ible as municipal re-Puse, industr:Lal waste, coal or -the
like.
