Title of Invention

METHOD AND APPARATUS FOR COOLING A MATERIAL TO BE REMOVED FROM THE GRATE OF A FLUIDIZED BED FURNACE

Abstract The invention relates to a method and an apparatus for cooling a material to be removed from the grate of a fluidized bed furnace. Material at a high temperature is passed from the grate of the fluidized bed furnace into a fluidized bed cooler in charges of a given size by measuring the quantity of the material accumulating in the fluidized bed cooler. When the quantity of the material in the cooler has reached a predetermined limit value, the supply of material into the fluidized bed cooler is prevented. The charge is cooled in the fluidized bed cooler by fluidization air and via heat transfer into a cooling liquid circulation system and the temperature of the charge is measured. The charge is removed when the temperature of the charge has fallen to a predetermined limit value.
Full Text METHOD AND APPARATUS FOR COOLING A MATERIAL TO BE RE-
MOVED FROM THE GRATE OF A FLUIDIZED BED FURNACE
FIELD OF THE INVENTION
The present invention relates to a method as
defined in the preamble of claim 1. Moreover, the in
vention relates to an apparatus as defined in the pre-
amble of claim 14.
BACKGROUND OF THE INVENTION
In prior art, specification US 4,227,488 dis-
closes an apparatus for cooling coarse material re-
moved from the grate of a fluidized bed furnace. The
apparatus comprises a supply conduit having an upper
first end, which opens to the grate of the fluidized
bed furnace to receive material to be cooled from the
grate into the supply conduit. Further, the apparatus
comprises a fluidized bed cooler. The fluidized bed
cooler has a housing, into the upper part of which the
lower, second end of the supply conduit opens. The
housing encloses an interior space for receiving the
material. Connected to the housing are cooling liquid
pipes for cooling the material in the interior space.
The apparatus further comprises a second grate having
a number of through holes. This second grate has been
arranged to divide the space inside the housing of the
fluidized bed cooler into a fluidized bed space above
the second grate, where the material to be cooled is
present as a fluidized bed, and an air distribution
space below the second grate. An air inlet duct opens
into the air distribution space to supply air into the
air distribution space, from where the air is passed
further through the openings of the second grate into
the fluidized bed space to fluidize and cool the mate-
rial to be cooled. An outlet conduit opens into the
fluidized bed space to remove the cooled material from
the fluidized bed space.
The cooling of the material removed from the
grate of the fluidized bed furnace is implemented in
such manner that material at a high temperature is
passed from the grate of the fluidized bed furnace
into the fluidized bed cooler, where the material is
cooled partly by fluidization air and partly by heat
transfer into a cooling liquid circulation system. The
cooled material is removed from the fluidized bed
cooler, to be passed further to other process equip-
ment. The purpose of the cooling is to reduce the tem-
perature of the material to a lower level such that
the material will not cause damage to the equipment
used in further processing. The material is allowed to
pass in a continuous flow from the fluidized bed fur-
nace through the fluidized bed cooler and further to
other process equipment.
A problem with the prior-art apparatus and
method is that the mass flow of the material to be re-
moved from the fluidized bed furnace and cooled can
not be controllably and accurately regulated.
A further problem is that, in cooling occur-
ring in a continuous flow, the material temperature
after the cooling may vary within wide limits and the
temperature can not be accurately adjusted as desired.
Further, specification EP 0 628 767 A2 dis-
closes a fluidized bed boiler designed for refuse in-
cineration and a method for its operation. Refuse in-
cineration produces ash, which consists of debris in-
troduced along with the feed material, clods accumu-
lated in the sand bed due to impurities, and the ac-
tual ash produced by combustion. Coarse material is
removed from the inclined grate of the fluidized bed
boiler into a separate cooler, where the material is
cooled charge by charge. The amounts of material re-
moved during the diurnal^ cycle are relatively small.
The material flows from the furnace into the cooler
along the inclined grate, which extends from the fur-
nace into the cooler. The movement of the material
into the cooler is controlled by means of horizontal
air jets from directional nozzles provided in the
grate. The material is removed from the cooler by
opening a discharge valve in an outlet conduit after
the material has been cooled to a desired temperature.
A problem with this prior-art apparatus and
method is that the mass flow of the material to be re-
moved from the fluidized bed furnace and cooled and
the quantity of the charge can not be accurately meas-
ured.
OBJECT OF THE INVENTION
The object of the present invention is to
overcome the above-mentioned drawbacks.
A specific object of the invention is to dis-
close a method and an apparatus whereby the mass flow
of the material to be removed from a fluidized bed
furnace and cooled and the final temperature after
cooling can be controllably adjusted.
A specific object of the invention is to dis-
close a method and an apparatus that are particularly
advantageous for use in conjunction with a metallurgic
calcining kiln, especially a zinc furnace.
BRIEF DESCRIPTION OF THE INVENTION
The method of the invention is characterized
by what is disclosed in claim 1. Furthermore, the ap-
paratus of the invention is characterized by what is
disclosed in claim 14.
In the method of the invention
a) a material charge containing material to
be cooled is loaded into a fluidized bed cooler,
b) during cooling, the temperature of the
charge is measured,
c) the cooled charge is removed from the flu-
idized bed cooler when the temperature of the charge
as indicated by the temperature measurement has fallen
to a predetermined limit value of temperature, and
d) steps a) - c) are repeated cyclically. Ac-
cording to the invention, during the loading step a) ,
the quantity of the material accumulating in the flu-
idized bed cooler is measured, and the supply of mate-
rial into the fluidized bed cooler is prevented when
the quantity of the material in the fluidized bed
cooler corresponds to a predetermined quantity of a
charge to be loaded at one time.
The apparatus of the invention comprises a
supply valve disposed at the second end of the supply
conduit, which supply valve in an open position allows
and in a closed position prevents the supply of mate-
rial into the fluidized bed space of the fluidized bed
cooler. To open and close the supply valve, a fix^t
power mgajia. is provided. Further, the apparatus com-
prises a discharge valve disposed in a discharge con-
duit, which discharge valve in an open position allows
and in a closed position prevents the passage of mate-
rial out of the fluidized bed space. To open and close
the discharge valve, a second power means is provided.
The apparatus further comprises quantity detection
means for producing quantity data regarding the quan-
tity of material in the fluidized bed space, and tem-
perature measuring means for producing temperature
data regarding the temperature of the material in the
fluidized bed space. Moreover, the apparatus comprises
a control device, which has been arranged to control
the first power means to open and close the supply
valve and the second power means to open and close the
discharge valve on the basis of the quantity data and
temperature data and predetermined limit values of
quantity and temperature, so that the loading of mate-
rial into the fluidized bed space of the fluidized bed
cooler and its cooling and removal from the fluidized
bed space take place in a charge-by-charge and cyclic
manner.
The method and apparatus of the invention
prevent excessive flow of material out of the fluid-
ized bed furnace, but they make it possible to get the
coarse fraction out in a charge-by-charge manner so
that the quantity of the charge is accurately con-
trolled. Due to the accurately controlled output flow
from the fluidized bed furnace and the cooling con-
trolled on the basis of its temperature, the mass flow
and quantity of the material to be passed out of the
fluidized bed furnace and cooled as well as the final
temperature after cooling can be controllably ad-
justed. Therefore, the counter-pressure of the bed in
the fluidized bed furnace and the composition of the
bed can be controllably regulated by making desired
adjustments of the quantity of material contained in
the material charge to be cooled. The apparatus can be
easily automated. The method and apparatus allow the
operator to know how much material is removed from the
furnace, because the charge size is controlled and the
number of charges (charges per hour) can be adjusted.
This makes it easy to increase or decrease the amount
of material to be removed from the furnace by changing
the times, in other words, if its preferable in re-
spect of furnace operation to remove more material by
underflow, then the operation is accelerated, or if it
is desirable to reduce the amount of material removed
by underflow, then the operation is slowed down. The
system enables controlled removal by underflow of a
quantity of material that is suitable in respect of
furnace operation. The quantity of material removed is
known and the quantity can be adjusted. This is part
of the control of the furnace. In addition, the tem-
perature is under control and the composition of the
material removed can be monitored by a sampling sys-
tem. The essential point is that the invention enables
an adjustable system to be achieved.
In an embodiment of the method, during the
loading step a), the surface level of the material ac-
cumulating in the fluidized bed cooler is measured,
and when the measured surface level has reached a pre-
determined limit value, which corresponds to a prede-
termined quantity of a charge to be loaded at one
time, the supply of material into the fluidized bed
cooler is prevented.
In an embodiment of the method, during the
loading step a), the fluidization air counter-pressure
caused by the material is measured, and when the meas-
ured counter-pressure has reached a predetermined
limit value, which corresponds to a predetermined
quantity of a charge to be loaded at one time, the
supply of material into the fluidized bed cooler is
prevented.
In an embodiment of the method, a supply con-
duit extending between the grate of the fluidized bed
furnace and the fluidized bed cooler is provided, and
during the loading step a) the material is allowed to
flow out from the grate via the supply conduit into
the fluidized bed cooler by gravitation.
In an embodiment of the method, the fluidized
bed cooler is provided with a discharge conduit for
the discharge of material from the fluidized bed
cooler, and during the discharge step c) the material
is allowed to flow out of the fluidized bed cooler via
the discharge conduit by gravitation.
In an embodiment of the method, the supply
conduit is cleaned periodically at regular or irregu-
lar time intervals.
In an embodiment of the method, the filling
time required for filling the fluidized bed cooler
with a material charge is determined, the measured
filling time is compared to a predetermined filling
time limit value, and if the measured filling time ex-
ceeds the predetermined limit value, then the supply
conduit is cleaned.
In an embodiment of the method, the supply
conduit is cleaned by blowing pressurized air through
the supply conduit.
In an embodiment of the method, the exhaus-
tion of the fluidized bed cooler is established on the
basis of a determination of surface level and/or coun-
ter-pressure after the surface level and/or counter-
pressure have/has fallen to predetermined limit val-
ues. After it has been established that the fluidized
bed cooler has become substantially exhausted, the
discharge conduit is closed. The supply conduit is
opened to load a new material charge into the fluid-
ized bed cooler. After the material charge has been
loaded, the supply conduit is closed. Via a tempera-
ture measurement, the cooling of the material charge
to the predetermined limit value of temperature is de-
tected. The discharge conduit is then opened to dis-
charge the charge from the fluidized bed cooler.
In an embodiment of the method, after the ma-
terial charge has been cooled, samples are repeatedly
taken from the cooled material, and the sample is ana-
lyzed to determine the current state of the bed in the
fluidized bed furnace.
In an embodiment of the method, the fluidized
bed furnace is used as a calcining kiln for the calci-
nation of an ore concentrate. The material to be re-
moved from the grate and cooled consists of coarse-
grained, substantially non-fluidizable calcine mate-
rial accumulated on the grate.
In an embodiment of the method, the material
charge is cooled from a temperature of about 900"C -
1000"C to a temperature of about 100"C - 400"C.
In an embodiment of the method, the material
to be cooled consists of calcine of zinc ore concen-
trate.
In an embodiment of the apparatus, the supply
valve is a flap valve.
In an embodiment of the apparatus, the dis-
charge valve is a flap valve.
In an embodiment of the apparatus, the quan-
tity detection means comprise a surface level detector


for determining the material surface level in the flu-
idized bed space.
In an embodiment of the apparatus, the sur-
face level detector is a surface level detector work-
ing on a radiometric level measurement principle and
comprising a radiation source and a detector, which
are mounted on the outside of the housing.
In an embodiment of the apparatus, the quan-
tity detection means comprise a pressure detector,
which is mounted in the air supply duct for measuring
the counter-pressure of the fluidization air.
In an embodiment of the apparatus, the appa-
ratus comprises a cleaning device for the cleaning of
the supply conduit.
In an embodiment of the apparatus, the con-
trol device comprises means arranged to determine the
filling time required for the loading of the fluidized
bed cooler with a material charge of a predetermined
size and to compare the measured filling time to a
predetermined limit value of filling time, and if the
measured filling time exceeds the predetermined limit
value of filling time, the control device has been ar-
ranged to instruct the cleaning device to clean the
supply conduit.
In an embodiment of the apparatus, the clean-
ing device is a pneumatic cleaning device, which has
been arranged to blow pressurized air into the supply
conduit.
In an embodiment of the apparatus, the clean-
ing device comprises a frame; a cleaning tube movably
supported on the frame; a third power means for moving
the cleaning tube, said third power means being con-
trollable by the control device; and means for supply-
ing pressurized air into the cleaning tube. The clean-
ing tube can be moved by the third power means between
a cleaning position and a rest position, in which
cleaning position the end of the cleaning tube is in-
side the second end of the supply conduit for blowing
pressurized air into the supply conduit, and in which
rest position the end of the cleaning tube is at a
distance from the second end of the supply conduit.
In an embodiment of the apparatus, the appa-
ratus comprises a sampling device connected to the
discharge conduit for taking samples from the cooled
material.
In an embodiment of the apparatus, the fluid-
ized bed furnace is a calcining kiln for the calcina-
tion of an ore concentrate, such as zinc ore concen-
trate, and the material to be cooled consists of
coarse-grained, substantially non-fluidizable calcine
material to be removed from the grate of the calcining
kiln.
In an embodiment of the apparatus, the fluid-
ized bed cooler has been fitted to cool the material
from 900"C - 1000"C to a temperature of about 100"C -
400'C.
LIST OF FIGURES
In the following, the invention will be de-
scribed in detail with reference to embodiment exam-
ples and the attached drawing, which is a diagrammatic
representation of an embodiment of the apparatus of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
The below-described example embodiment of the
invention relates to calcination of zinc concentrate
in connection with hydrometallurgic zinc production.
The purpose of the calcination of the concentrate is
to convert sulfidic zinc into a soluble form before a
solution treatment. This is accomplished in a fluid-
ized bed furnace where, after ignition, the concen-
trate bed is oxidized at a temperature of about 900"C
- lOOO'C.
Although the invention is described here in
connection with zinc production, it is applicable for


any other purpose where fluidized bed furnaces are
used and a hot particulate solid material is to be
cooled to a lower temperature before being passed on
for further treatment. Thus, the fluidized bed furnace
may be e.g. a fluidized bed furnace intended for power
plant use or the like.
From the calcining kiln, the calcine produced
is removed at a rate of 5 - 8 t/h, most of which comes
out by overflow of the calcining kiln while some of it
drifts out with gas and is recovered in a boiler, cy-
clones and electric filters. In some calcining kilns,
some of the calcine is extracted from the kiln by so-
called underflow. By underflow of the kiln, even
coarser non-fluidizable agglomerates formed in the
kiln can be extracted. This coarse material consists
of pellets of relatively regular particle size. Its
particle size is such that the material will not rise
at the speed of the fluidization gas, at 0.5 - 0.7
m/s, to overflow, but remains lying on the grate and
gradually forms excrescences. The formation of coarse
material depends on the impurity components of the
feed mixture (Pb, Cu etc. contained in the concen-
trate) . It is expressly inqportant that, at the outlet
of the calcining kiln, these pellets be extracted in a
controlled manner because this affects the quantity in
the bed in the kiln, and in metallurgic processes the
delay also has an effect on the occurrence and degrees
of reaction of the desired reactions. Depending on the
concentrate, the oxidization of e.g. an 8-mm pellet
takes from 30 minutes to two hours, so it is expressly
important that the outlet flow be accurately con-
trolled.
Unless the coarse calcine is discharged from
the kiln, it may gradually accumulate on the grate in
amounts large enough to cause problems, such as e.g.
poor fluidization of the bed and/or formation of
sinter on the bottom of the kiln and an increase of
the counter-pressure produced by the bed. When impure


concentrates are used, molten phases easily appear
and, as a consequence of these, agglomerates are
formed on the grate. The apparatus presented in the
figure has been arranged to remove coarse material as
referred to above from the grate 2 of a fluidized bed
furnace 1 and to cool it from a temperature of about
900°C - 1000°C to a temperature of about 100°C - 400°C.
The apparatus comprises a supply conduit 3
having an upper first end 4 and a lower second end 5.
The first end 4 of the supply conduit 3 opens onto the
horizontal grate 2 of the fluidized bed furnace 1 so
that the material to be cooled can enter from the
grate 2 into the supply conduit 3. The apparatus com-
prises a fluidized bed cooler 6. The fluidized bed
cooler comprises a housing 7, and the second end 5 of
the supply conduit 3 opens into the upper part of the
housing. The housing 7 encloses an interior space. At-
tached to the wall of the housing 7 are cooling liquid
tubes 8, in which a cooling liquid, such as water, is
circulated to cool the material to be received into
the interior space. Provided in the lower part inside
the housing 7 is a second grate 9, which is provided
with a number of through holes 10. The second grate 9
divides the interior space of the housing into a flu-
idized bed space 11 above the second grate 9, where
the material to be cooled is present as a fluidized
bed or mattress, and an air distribution space 12 be-
low. An air supply duct 13 opens into the air distri-
bution space 12 to supply air into the air distribu-
tion space 12. From the air distribution space 12, the
air flows through the holes 10 of the second grate 9
into the fluidized bed space 11, fluidizing the mate-
rial to be cooled that is present there and at the
same time cooling it. A discharge conduit 14 opens
into the lower part of the fluidized bed space 11
above the second grate 9 to remove the cooled material
from the fluidized bed space.
The second end 5, i.e. the lower end of the
supply conduit 3 is provided with a supply valve 5,
which is a flap valve. When the flap of the supply
valve 5 is in the open position, it permits the supply
of material from the supply conduit 3 into the fluid-
ized bed space 11. Similarly, when the flap of the
supply valve 5 is in the closed position, it prevents
the supply of material from the supply conduit 3 into
the fluidized bed space 11. A first power means 16 has
been arranged to open and close the flap of the supply
valve 15.
The discharge conduit 14 is provided with a
discharge valve 17, which is a flap valve. When the
flap of the discharge valve 17 is in the open posi-
tion, it permits the passage of material out of the
fluidized bed space 11 into the discharge conduit 14.
Similarly, when the flap of the discharge valve 17 is
in the closed position, it prevents the passage of ma-
terial out of the fluidized bed space 11. A second
power means 18 has been arranged to open and close the
flap of the discharge valve 17.
To generate quantity data regarding the quan-
tity of material in the fluidized bed space 11, quan-
tity detection means 19, 20 are provided. The quantity
detection means comprise a surface level detector 19,
which determines the surface level of the material in
the fluidized bed space 11. The surface level detector
19 is preferably a surface level detector working on a
radiometric level measurement principle and comprising
a radiation source and a detector, which are mounted
on the outside of the housing 7. In radiometric level
measurement, the level of the surface is determined on
the basis of the attenuation of gamma radiation occur-
ring in a medium. The measuring equipment consists of
a gamma radiator and a detector, which may be either
an ionization chamber or a scintillation counter. Both
the radiation source and the detector are mounted on
the outside of the housing 7, and thus the effect of
the medium, temperature and vibration on the measure-
ment is eliminated. Furthermore, the quantity detec-
tion means comprise a pressure detector 20, which is
mounted in the air supply duct 13 to measure the coun-
ter-pressure of fluidization air.
The apparatus further comprises temperature
measuring means 21 for generating temperature data re-
garding the temperature of the material in the fluid-
ized bed space.
A control device 22 has been arranged to con-
trol the first power means 16 to open and close the
supply valve 15 and the second power means 18 to open
and close the discharge valve 17 on the basis of the
material quantity data and temperature data and the
predetermined limit values of quantity and temperature
so that the loading of material into the fluidized bed
space of the fluidized bed cooler, its cooling and re-
moval from the fluidized bed space take place in a
charge-by-charge and cyclic manner as described above.
The apparatus further comprises a cleaning
device 23 for cleaning the supply conduit 3.
The cleaning device 23 is a pneumatic clean-
ing device, which has been arranged to blow pressur-
ized air into the supply conduit 3. The cleaning de-
vice 23 comprises a frame 24. A cleaning tube 25,
through which pressurized air can be blown, is sup-
ported on the frame 24 so as to be movable back and
forth substantially in the same direction in which the
supply conduit 3 extends. The cleaning tube 25 is
moved by a third power means 26. The third power means
can also be controlled by the control device 22.
The cleaning tube 25 can be moved between a
cleaning position and a rest position by the third
power means 26. In the cleaning position, the flap of
the supply valve 15 is in the open position to allow
the end 27 of the cleaning txibe 25 to be inserted into
the second end 5 of the supply conduit 3 so that pres-
surized air can be blown from the cleaning tube 25
into the supply conduit 4 to blow any material ob-
structing it back into the fluidized bed furnace 1. In
the rest position, the end 27 of the cleaning tube 25
is withdrawn to a distance from the second end 5 of
the supply conduit 3.
The apparatus further comprises a sampling
device 28 connected to the discharge conduit 14. The
sampling device 28 makes it possible to take samples
from the cooled material. The samples are analyzed to
determine the current state of the bed in the fluid-
ized bed furnace. The quality of the bed and the state
of the furnace can be monitored by determining the
particle size distribution of the sample and perform-
ing a chemical analysis on it.
The apparatus works automatically under con-
trol of the control device 22 as follows.
To load a first material charge into the flu-
idized bed cooler, the control device 22 gives a com-
mand to the first power means 16 to open the supply
valve 15 so that the hot coarse-grained material can
gravitate through the supply conduit 3 into the fluid-
ized bed space 11 of the fluidized bed cooler 6. The
discharge valve 17 in the discharge conduit 14 is in
the closed position.
The surface level of the material accumulat-
ing in the fluidized bed cooler is measured continu-
ously by the surface level detector 19 during the
loading phase. When the material surface level has
reached a predetermined limit value, which corresponds
to the quantity of material in a charge to be loaded
at one time, the control device 22 gives a command to
the first power means 16 to close the supply valve 15.
Instead of or along with the surface level measure-
ment, the counter-pressure produced by the material in
the fluidized bed space and acting against the supply
of fluidization air can be measured by means of the
pressure detector, and the supply valve 15 can be
closed when the counter-pressure exceeds a predeter-
mined limit value, which corresponds to the counter-
pressure produced by the predetermined quantity of
charge to be loaded at one time, indicating that a
full charge has been reached.
In the fluidized bed cooler 6, the material
charge is cooled by the fluidization air and the cool-
ing liquid circulation 8 in the housing 7. The cooling
is mainly effected via heat transfer into the cooling
liquid. During the cooling, the temperature of the ma-
terial charge is measured by a temperature detector
21, which transmits the temperature data to the con-
trol device 22. The control device 22 senses the cool-
ing of the material charge to the predetermined limit
value, which can be selected e.g. from the range of
lOO'C - 400*'C. The control device 22 issues a command
to the second power means 18 to open the discharge
valve 17 so that the cooled material charge can be
discharged into the discharge conduit 14. At the same
time, the surface level detector 19 measures the sur-
face level of the material in the fluidized bed space
11 and/or the pressure detector 20 measures the coun-
ter-pressure to determine whether the fluidized bed
space 11 has been emptied. When the measured surface
level and/or counter-pressure falls below the prede-
termined limit value, which means that the material
charge has been substantially discharged into the dis-
charge conduit 14, the control device 22 issues a sec-
ond command to the second power means 18 to close the
discharge valve 17 and a command to the first power
means 16 to open the supply valve 15 so that the next
material charge can be passed into the fluidized bed
cooler 6. These steps are repeated.
The supply conduit 3 is cleaned periodically
by the cleaning device 23 at regular or irregular time
intervals. The control device 22 is provided with a
clock, which measures the filling time required for
loading the fluidized bed cooler 6 with a material
charge of predetermined size. The control device 22
compares the measured filling time to a predetermined
limit value of filling time. If the measured filling
time exceeds the predetermined limit value, which
means that the supply conduit is partly or completely
blocked, then the control device 22 will instruct the
cleaning device 23 to clean the supply conduit 3.
The invention is not limited to the embodi-
ment examples described above; instead, many varia-
tions are possible within the scope of the inventive
concept defined in the claims.
CLAIMS
1. A method for cooling a material to be re-
moved from the grate of a fluidized bed furnace, in
which method the material at a high temperature is
passed from the grate of the fluidized bed furnace
into a separate fluidized bed cooler, the material is
cooled in the fluidized bed cooler partly by fluidiza-
tion air and partly by heat transfer into a cooling
liquid circulation system, and the cooled material is
discharged from the fluidized bed cooler, and in which
method
a) a charge of material containing material
to be cooled is loaded into the fluidized bed cooler,
b) during cooling, the temperature of the
charge is measured,
c) the cooled charge is discharged from the
fluidized bed cooler when the temperature of the
charge as indicated by the temperature measurement has
fallen to a predetermined limit value of temperature,
and
d) steps a) - c) are repeated cyclically,
characterized in that, during the loading step
a) , the quantity of the material accumulating in the
fluidized bed cooler is measured, and the supply of
material into the fluidized bed cooler is prevented
vhen the quantity of the material in the fluidized bed
cooler corresponds to a predetermined quantity of a
charge to be loaded at one time.
2. A method according to claim 1, c h a r a c -
terized in that during the loading step a) , the
surface level of the material accumulating in the flu-
idized bed cooler is measured, and when the measured
surface level has reached a predetermined limit value,
which corresponds to a predetermined quantity of a
charge to be loaded at one time, the supply of mate-
rial into the fluidized bed cooler is prevented.
3. A method (according to claim 1 or 2,
characterized in that during the loading step
a), the fiuidization air counter-pressure caused by
the material is measured, and when the measured coun-
ter-pressure has reached a predetermined limit value
which corresponds to a predetermined quantity of a
charge to be loaded at one time, the supply of mate-
rial into the fluidized bed cooler is prevented.
4. A method (according to any one of claims 1
- 3 characteri zed in that a supply conduit
extending between the grate of the fluidized bed fur-
nace and the fluidized bed cooler is provided, and
during the loading step a) the material is allowed to
flow out from the grate via the supply conduit into
the fluidized bed cooler by gravitation.
5. A method (according to any one of claims 1
- 4, characterized in that the fluidized bed
cooler is provided with a discharge conduit for dis-
charge of material from the fluidized bed cooler, and
during the discharge step c) the material is allowed
to flow out of the fluidized bed cooler via the dis-
charge conduit by gravitation.
6. A method according to any one of claims 1
- 5, c haracterized in that; the supply conduit
is cleaned periodically at regular or irregular time
intervals.
7. A method according to any one of claims 1
- 6, c h a r a cterized in that the filling time
required for filling the fluidized bed cooler with a
material charge is determined, the measured filling
time is compared to a predetermined filling time limit
value, and if the measured filling time exceeds the
predetermined limit value, then the supply conduit is
cleaned.
8. A method according to claim 6 or 7,
characterized in that the supply conduit is
cleaned by blowing pressurized air through the supply
conduit.


9. A method according to any one of claims 1
- 8, charac terized in thats
- the exhaustion of the fluidized bed cooler
is established on the basis of a determination of sur-
face level and/or counter-pressure after the surface

level and/or counter-pressure have/has fallen to pre-
determined limit values,
- after it has been established that the flu-
idized bed cooler has become substantially exhausted,
the discharge conduit is closed,
- the supply conduit is opened to load a ma-
terial charge to be cooled into the fluidized bed
cooler,
- the supply conduit is closed after the ma-
terial charge has been loaded,
the cooling of the material charge to the
predetermined limit value of temperature is detected
via a temperature measurement, and
- the discharge conduit is opened to remove
the charge,
10. A method according to any one of claims 1
-9 characterized in tht, after the material
charge has been cooled, samples are repeatedly taken
from the cooled material, and the sample is analyzed
to determine the current state of the bed in the flu-
idized bed furnace.
11. A method according to any one of claims 1
- 10, character i z e d in that the fluidized bed
furnace is used as a calcining kiln for the calcina-
tion of an ore concentrate, and the material to be re-
moved from the grate and cooled consists of coarse-
grained, substantially non-fluidizable calcine mate-
rial accumulated on the grate.
12. A method according to claim 11, c h a r -
acterized in that the material charge is cooled
trom a temperature of about 900°C - 1000°C to a tem-
perature of about 100°C - 400°C.
13. A method According to claim 11 or 12,
characterized in that the material to be
cooled consists of calcine of zinc ore concentrate.
-— 14. An apparatus for cooling a material to be
removed from a first grate (2) of a fluidized bed fur-
nace (1), said apparatus comprising
- a supply conduit (3) having an upper first
end (4) , which opens onto the first grate (2) to re-
ceive the material to be cooled from the grate (2)
into the supply conduit (3) , and a lower second end
(5),
- a fluidized bed cooler (6), which comprises
-- a housing (7) , into the upper part of
which the second end (5) of the supply conduit (3)
opens, which housing encloses an interior space for
receiving the material and to which housing are con-
nected cooling liquid tubes (8) for cooling the mate-
rial in the interior space,
--a second grate 9, which is provided with a
number of through holes (10) and which second grate
has been arranged to divide the interior space of the
housing into a fluidized bed space (11) above the sec-
ond grate, where the material to be cooled is present
as a fluidized bed, and an air distribution space (12)
below the second grate,
-- an air supply duct (13), which opens into
the air distribution space (12) to supply air into the
air distribution space and from there further through
the holes (10) of the second grate (9) into the fluid-
ized bed space (11) for fluidizing and cooling the ma-
terial to be cooled, and
-- discharge conduit (14), which opens into
the fluidized bed space (11) to remove cooled material
from the fluidized bed space,
- a discharge valve (17) provided in the dis-
charge conduit (14), which discharge valve in an open
position allows and in a closed position prevents the
passage of material out of the fluidized bed space
(11) ,
- a second power means (18) for opening and
closing the discharge valve (17), and
- temperature measuring means (21) for pro-
ducing temperature data regarding the temperature of
the material in the fluidized bed space, charac-
terized in that the apparatus comprises
- a supply valve (15) disposed at the second
end (5) of the supply conduit (3) , which supply valve
in an open position allows and in a closed position
prevents the supply of material into the fluidized bed
space (11),
- a first power means (16) for opening and
closing the supply valve (15),
- quantity detection means '(19, 20) for pro-
ducing quantity data regarding the quantity of mate-
rial in the fluidized bed space (11), and
- a control device (22) , which has been ar-
ranged to control the first power means (16) for open-
ing and closing the supply valve (15) and the second
power means (18) for opening and closing the discharge
valve (17) on the basis of the quantity data and tem-
perature data and predetermined limit values of quan-
tity and temperature, so that the loading of material
into the fluidized bed space of the fluidized bed
cooler and its cooling and removal from the fluidized
bed space take place in a charge-by-charge and cyclic
manner.
15. An apparatus acccording to claim 14,
characterized in that) the supply valve (15) is
a flap valve.
16. An apparatus according to claim 14 or 15,
characterized in that the discharge valve (17)
is a flap valve.
17. An apparatus according to any one of
claims 14 - 16, characterized in that the
quantity detection means comprise a surface level de-


tector (19) for determining the material surface level
in the fluidized bed space (11).
18. An apparatus according to claim 15,
characterizedin that the surface level detec-
tor (19) is a surface level detector working on a ra-
diometric level measurement principle and comprising a
radiation source and a detector, which are mounted on
the outside of the housing (7)
19. An apparatus according to any one of
claims 14 - 18, characterized in that the
quantity detection means comprise a pressure detector
(20), which is mounted in the air supply duct (13) for
measuring the counter-pressure of the fluidization
air.
20. An apparatus according to any one of
claims 14 - 19, characte r i z e d in that the ap-
paratus comprises a cleaning device (23) for the
cleaning of the supply conduit (3).
21. An apparatus according to claim 20,
characterized in that the control device (22)
comprises means arranged to determine the filling time
required for the loading of the fluidized bed cooler
with a material charge of a predetermined size and to
compare the measured filling time to a predetermined
limit value of filling time, and if the measured fill-
ing time exceeds the predetermined limit value of
filling time, the control device (22) has been ar-
ranged to instruct the cleaning device (23) to clean
the supply conduit.
22. An apparatus/according to claim 20 or 21,
characterized in that the cleaning device (23)
is a pneumatic cleaning device, which has been ar-
ranged to blow pressurized air into the supply conduit
(3) .
23. An apparatus according to claim 22,
characterized in that the cleaning device (23)
comprises a frame (24) ,- a cleaning tube (25) movably
supported on the frame (24); a third power means (26)
for moving the cleaning tube, said third power means
being controllable by the control device (22); and
means for supplying pressurized air into the cleaning
tube, the cleaning tube (25) being movable by the
third power means between a cleaning position and a
rest position, and in which cleaning position the end
of the cleaning tube (25) is inside the second end (5)
of the supply conduit (3) for blowing pressurized air
into the supply conduit, and in which rest position
the end (27) of the cleaning tube (25) is at a dis-
tance from the second end (5) of the supply conduit

24. An apparatus according to any one of
claims 14 - 23, ch a r a c t e r i z e d in that the ap-
paratus comprises a sampling device (28) connected to
the discharge conduit (14) for taking samples from the
cooled material.
25. An apparatus according to any one of
claims 14 - 24, characterized in that the flu-
idized bed furnace (1) is a calcining kiln for the
calcination of an ore concentrate, such as zinc ore
concentrate, and the material to be cooled consists of
coarse-grained, substantially non-fluidizable calcine
material to be removed from the grate of the calcining
kiln.
26. An apparatus vaccordingf to claim 25,
characterized in that the fluidized bed cooler
(6) has been fitted to cool the material from a tem-
perature of about 900°C - 1000°C to a temperature of
about 100°C - 400°C.

The invention relates to a method and an apparatus for cooling a material to be removed from the grate of a fluidized
bed furnace. Material at a high temperature is passed from the grate of the fluidized bed furnace into a fluidized bed cooler in charges
of a given size by measuring the quantity of the material accumulating in the fluidized bed cooler. When the quantity of the material
in the cooler has reached a predetermined limit value, the supply of material into the fluidized bed cooler is prevented. The charge is
cooled in the fluidized bed cooler by fluidization air and via heat transfer into a cooling liquid circulation system and the temperature
of the charge is measured. The charge is removed when the temperature of the charge has fallen to a predetermined limit value.

Documents:

00098-kolnp-2006-abstract.pdf

00098-kolnp-2006-claims.pdf

00098-kolnp-2006-description complete.pdf

00098-kolnp-2006-drawings.pdf

00098-kolnp-2006-form 1.pdf

00098-kolnp-2006-form 3.pdf

00098-kolnp-2006-form 5.pdf

00098-kolnp-2006-international publication.pdf

00098-kolnp-2006-international search authority.pdf

00098-kolnp-2006-pct forms.pdf

98-kolnp-2006-abstract.pdf

98-KOLNP-2006-ABSTRACT_1.1.pdf

98-kolnp-2006-assignment.pdf

98-KOLNP-2006-ASSIGNMENT_1.1.pdf

98-KOLNP-2006-CANCELLED PAGES_.pdf

98-kolnp-2006-claims.pdf

98-KOLNP-2006-CLAIMS_1.1.pdf

98-KOLNP-2006-CORRESPONDENCE 1.1.pdf

98-kolnp-2006-correspondence.pdf

98-kolnp-2006-description (complete).pdf

98-KOLNP-2006-DESCRIPTION (COMPLETE)_1.1.pdf

98-kolnp-2006-drawings.pdf

98-KOLNP-2006-DRAWINGS_1.1.pdf

98-kolnp-2006-examination report.pdf

98-KOLNP-2006-FORM 1.1.1.pdf

98-kolnp-2006-form 1.pdf

98-KOLNP-2006-FORM 13_.pdf

98-kolnp-2006-form 18.pdf

98-KOLNP-2006-FORM 2_.pdf

98-KOLNP-2006-FORM 3.1.1.pdf

98-kolnp-2006-form 3.pdf

98-KOLNP-2006-FORM 5.1.1.pdf

98-kolnp-2006-form 5.pdf

98-KOLNP-2006-FORM-27.pdf

98-kolnp-2006-gpa.pdf

98-KOLNP-2006-INTENATIONAL PUBLICATION_1.1.pdf

98-KOLNP-2006-OTHERS_.pdf

98-KOLNP-2006-PA_.pdf

98-KOLNP-2006-PETITION UNDER RULE 137_.pdf

98-KOLNP-2006-REPLY TO EXAMINATION REPORT_.pdf

98-kolnp-2006-specification.pdf

98-KOLNP-2006-TRANSLATED COPY OF PRIORITY DOCUMENT_.pdf

abstract-00098-kolnp-2006.jpg


Patent Number 244799
Indian Patent Application Number 98/KOLNP/2006
PG Journal Number 52/2010
Publication Date 24-Dec-2010
Grant Date 20-Dec-2010
Date of Filing 12-Jan-2006
Name of Patentee OUTOTEC OYJ
Applicant Address P.O. BOX 86, RIIHITONTUNTIE 7, FI-02200 ESPOO
Inventors:
# Inventor's Name Inventor's Address
1 NYBERG JENS MATRUUSINKATU 3 D 7, FI-67100 KOKKOLA
2 SIIRILA HEIKKI PARKKI 23, FI-67300 KOKKOLA
3 PERALAHTI HEIKKl STRANGINTIE 3, FI-67400 KOKKOLA
4 KARTSALO VESA SOKOJANTIE 866, FI-67100 KOKKOLA
PCT International Classification Number F23C 10/24, 10/28
PCT International Application Number PCT/FI2004/000454
PCT International Filing date 2004-07-14
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 20031113 2003-07-29 Finland