U.S. patent application number 10/040333 was filed with the patent office on 2002-05-16 for method and apparatus for detecting agglomerates.
This patent application is currently assigned to SUMITOMO CHEMICAL COMPANY, LIMITED. Invention is credited to Konaka, Tsutomu, Takimiya, Koji, Tamura, Mitsuru.
Application Number | 20020056312 10/040333 |
Document ID | / |
Family ID | 18419992 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020056312 |
Kind Code |
A1 |
Tamura, Mitsuru ; et
al. |
May 16, 2002 |
Method and apparatus for detecting agglomerates
Abstract
Agglomerates 20 in a mixed phase container 1 are detected by
measuring strain in a detecting rod 50 disposed in the mixed phase
container 1 in which a mixed phase of gas and powders is formed.
The detecting rod 50 is disposed at an insertion angle .theta. in
the range from 20 degrees to 70 degrees with relation to the flow
of gas and powders.
Inventors: |
Tamura, Mitsuru;
(Sodegaura-shi, JP) ; Takimiya, Koji;
(Sodegaura-shi, JP) ; Konaka, Tsutomu;
(Ichihara-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 Pennsylvania Avenue, NW
Washington
DC
20037-3213
US
|
Assignee: |
SUMITOMO CHEMICAL COMPANY,
LIMITED
|
Family ID: |
18419992 |
Appl. No.: |
10/040333 |
Filed: |
January 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10040333 |
Jan 9, 2002 |
|
|
|
09575248 |
May 22, 2000 |
|
|
|
Current U.S.
Class: |
73/61.71 ;
422/131; 526/59; 526/74; 73/760 |
Current CPC
Class: |
G01N 2015/0092 20130101;
B01J 8/1809 20130101; B01J 2208/00681 20130101; Y10S 526/901
20130101; C08F 10/00 20130101; C08F 10/00 20130101; C08F 2/01
20130101; C08F 10/00 20130101; C08F 2/34 20130101; C08F 10/00
20130101; C08F 2/002 20130101 |
Class at
Publication: |
73/61.71 ;
526/74; 526/59; 73/760; 422/131 |
International
Class: |
G01N 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1999 |
JP |
11-351843 |
Claims
What is claimed is:
1. A method for detecting agglomerates in a mixed phase container
by measuring strain in a detecting rod disposed in said mixed phase
container in which a mixed phase of gas and powders such as
products of the olefin polymer and/or catalysts is formed, wherein
said detecting rod is disposed at an insertion angle in the range
from 20 degrees to 70 degrees with relation to the flow of gas and
powders.
2. A method for detecting agglomerates according to claim 1,
wherein the detecting rod is disposed horizontally at an insertion
angle in the range from 20 degrees to 70 degrees with relation to
the flow of gas and powders.
3. A method for detecting agglomerates according to claim 1,
wherein a distributor plate is disposed on the bottom of said mixed
phase container for diffusing the gas in a horizontal direction,
and said detecting rod is positioned at a predetermined height
above said distributor plate.
4. An apparatus for detecting agglomerates in a mixed phase
container by strain detecting means in a detecting rod disposed in
the mixed phase container in which a mixed phase of gas and powders
is formed, wherein said detecting rod is disposed at an insertion
angle in the range from 20 degrees to 70 degrees with relation to
the flow of gas and powders.
5. An apparatus for detecting agglomerates according to claim 4,
wherein said detecting rod is disposed horizontally at an insertion
angle in the range from 20 degrees to 70 degrees with relation to
the flow of gas and powders.
6. An apparatus for detecting agglomerates according to claim 4,
wherein a distributor plate is disposed on the bottom of said mixed
phase container for diffusing the gas in a horizontal direction,
and said detecting rod is positioned at a predetermined height
above said distributor plate.
7. A fluidized-bed olefin polymerization reactor wherein a mixed
phase of gas and powders is formed, said reactor comprising an
apparatus for detecting agglomerates in said mixed phase, said
apparatus having a detecting rod for measuring strain when said
agglomerates collide thereto, wherein said detecting rod is
disposed at an insertion angle in the range from 20 degrees to 70
degrees with relation to the flow of gas and powders.
8. A fluidized-bed olefin polymerization reactor according to claim
7, wherein the detecting rod is disposed horizontally at an
insertion angle in the range from 20 degrees to 70 degrees with
relation to the flow of gas and powders.
9. A fluidized-bed olefin polymerization reactor according to claim
7, wherein a distributor plate is disposed on the bottom of said
mixed phase container for diffusing the gas in a horizontal
direction, and said detecting rod is positioned at a predetermined
height above said distributor plate.
10. An olefin polymerization method, comprising: detecting
agglomerates in a mixed phase container by measuring strain in a
detecting rod disposed in said mixed phase container in which a
mixed phase of gas and powders is formed, wherein said detecting
rod is disposed at an insertion angle in the range from 20 degrees
to 70 degrees with relation to the flow of gas and powders; and
removing said agglomerates from said mixed phase container.
11. An olefin polymerization method according to claim 10, wherein
the detecting rod is disposed horizontally at an insertion angle in
the range from 20 degrees to 70 degrees with relation to the flow
of gas and powders.
12. An olefin polymerization method, according to claim 10, wherein
a distributor plate is disposed on the bottom of said mixed phase
container for diffusing the gas in a horizontal direction, and said
detecting rod is positioned at a predetermined height above said
distributor plate.
13. A method for manufacturing an olefin polymer, said method
comprising: detecting agglomerates in a mixed phase container by
measuring strain in a detecting rod disposed in said mixed phase
container in which a mixed phase of gas and powders is formed,
wherein said detecting rod is disposed at an insertion angle in the
range from 20 degrees to 70 degrees with relation to the flow of
the gas and powders; and removing said agglomerates from said mixed
phase container.
14. A method for manufacturing an olefin polymer according to claim
13, wherein the detecting rod is disposed horizontally at an
insertion angle in the range from 20 degrees to 70 degrees with
relation to the flow of gas and powders.
15. A method for manufacturing an olefin polymer according to claim
13, wherein a distributor plate is disposed on the bottom of said
mixed phase container for diffusing the gas in a horizontal
direction, and said detecting rod is positioned at a predetermined
height above said distributor plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and apparatus for
detecting agglomerates formed in a mixed phase container such as a
fluidized-bed olefin polymerization reactor container, and to a
method and apparatus for fluidized-bed olefin polymerization.
[0003] 2. Description of the Related Art
[0004] It is well known in the art that a method of radiation is
being used for detecting agglomerates formed in a mixed phase
container, such as a fluidized-bed olefin polymerization reactor
container (refer to Japanese Patent Publication No.62-28961). In
the radiation method, a radiation source is placed in the center of
the container and a plurality of radiation detectors are disposed
around the container. In order to detect the existence and the size
of agglomerates, the detectors detect density fluctuations in the
mixed phase between the radiation source and the detectors by using
the radiation.
[0005] Another method for detecting agglomerates in the mixed phase
container, shown in Japanese Laid-open Patent Publication
No.4-361150, employs an electrostatic capacitance detecting method.
Means for detecting electrostatic capacitance is disposed on the
inner wall of the mixed phase container. This method is based on
detecting fluctuations of electrostatic capacitance, since the
density (dielectric constant) of agglomerates is greater than that
of the mixed phase. When the agglomerates as gel-like are formed
and attached on the wall in the mixed phase container, the
detecting means detects fluctuations in the electrostatic
capacitance thereof. Therefore, the detecting means is able to
monitor the state of agglomerates by measuring the amount of
fluctuations in electrostatic capacitance.
[0006] Further, another method for detecting agglomerates employs a
detecting rod having a strain detecting means in the mixed phase
container, as shown in Japanese Laid-open Patent Publication
No.10-36447. According to this method, it is possible to detect the
existence and the size of agglomerates formed in the mixed phase
container by detecting an amount of the strain generated in the
detecting rod when agglomerates collide with the detecting rod.
[0007] However, the method described above employing radiation to
detect agglomerates requires special attention. For example, a
fluidized-bed olefin polymerization reactor container is generally
an enormous container of roughly cylindrical shape having a
diameter of several meters and a height of several tens of meters.
A worker must enter the container to remove the blockage when
blockage occurs, or to perform the inspections at periodic
inspections. Accordingly, since a radiation source is present in
the container, sufficient considerations must be made to ensure the
safety of workers performing such operations.
[0008] While the method employing an electrostatic capacitance
detecting means to detect agglomerates is suitable for detecting
agglomerates adhered to the inner walls of the container and has no
problem related to safety, the method is not sufficiently precise
for detecting agglomerates which are moving within the container.
Further, since the difference between the density of small
agglomerates and that of normal olefin polymer product is small,
this method is not sufficient even for detecting agglomerates
adhered to the inner walls of the container.
[0009] The method of detecting agglomerates using a strain
detecting device does not have the problems described above.
However, in this method, it is essential that the agglomerates
effectively collide with the detecting rod. Since the agglomerates
formed in the container move along with the flow of gas and powders
such as products of the olefin polymer and/or catalysts in the
mixed phase, it is necessary to know beforehand how gas and powders
in the mixed phase will flow. Or else, agglomerates will not
collide with the detecting rod with an effective force, thereby
greatly lowering the sensitivity of detection.
[0010] If the detecting rod and the direction in which gas and
powders flow form a right angle or obtuse angle, agglomerates
moving along with the flow of gas and powders may get caught and
accumulate on the part of the detecting rod facing with the flow.
If agglomerates adhere to the detecting rod in this way, not only
it is impossible to precisely detect the agglomerates, but also the
accumulating agglomerates actually block detection of other
agglomerates in the container. As the agglomerates accumulate
further, it is very likely that the accumulation will obstruct
fluidization in the container and promote further
agglomeration.
SUMMARY OF THE INVENTION
[0011] The present invention has been made in view of the above
drawbacks. It is an object of the present invention to provide a
safe method and apparatus capable of detecting even small
agglomerates with a high degree of precision and sensitivity and
without obstructing fluidization within the mixed phase container.
It is another object of the present invention to provide a method
and apparatus for fluidized-bed olefin polymerization.
[0012] According to an aspect of the present invention, there is
provided a method for detecting agglomerates in a mixed phase
container by measuring strain in a detecting rod disposed in the
mixed phase container in which a mixed phase of gas and powders is
formed, wherein the detecting rod is disposed at an insertion angle
in the range from 20 degrees to 70 degrees, preferably from 25
degrees to 50 degrees, with relation to the flow of gas and
powders. This method can prevent the agglomerates formed in the
mixed phase container from accumulating on the part of the
detecting rod facing with the flow.
[0013] According to another aspect of the present invention, there
is provided a method for detecting agglomerates, wherein a
distributor plate specially designed to swirl gas and powders above
the plate (referred to as distributor plate hereinafter) is
disposed on the bottom of the mixed phase container for diffusing
the gas in a horizontal direction, and the detecting rod is
positioned at a predetermined height above the distributor plate.
This method can control the flow of gas and powders within the
mixed phase container, thereby effectively forcing the agglomerates
to collide with the detecting rod.
[0014] According to another aspect of the present invention, there
is provided an apparatus for detecting agglomerates in a mixed
phase container by strain detecting means in a detecting rod
disposed in the mixed phase container in which a mixed phase of gas
and powders is formed, wherein the detecting rod is disposed at an
insertion angle in the range from 20 degrees to 70 degrees with
relation to the flow of gas and powders. This arrangement can
prevent the agglomerates formed in the mixed phase container from
accumulating on the part of the detecting rod facing with the flow
more effectively.
[0015] According to another aspect of the present invention, there
is provided an apparatus for detecting agglomerates, wherein a
distributor plate is disposed on the bottom of the mixed phase
container for diffusing the gas in a horizontal direction, and the
detecting rod is positioned at a predetermined height above the
distributor plate. This arrangement can control the flow of gas and
powders within the mixed phase container, thereby effectively
forcing the agglomerates to collide with the detecting rod.
[0016] According to another aspect of the present invention, there
is provided a fluidized-bed olefin polymerization reactor wherein a
mixed phase of gas and powders is formed, the reactor comprising an
apparatus for detecting agglomerates in the mixed phase, the
apparatus having a detecting rod for measuring strain when the
agglomerates collide thereto, wherein the detecting rod is disposed
at an insertion angle in the range from 20 degrees to 70 degrees
with relation to the flow of gas and powders.
[0017] According to another aspect of the present invention, there
is provided an olefin polymerization method, comprising: detecting
agglomerates in a mixed phase container by measuring strain in a
detecting rod disposed in the mixed phase container in which a
mixed phase of gas and powders is formed, wherein the detecting rod
is disposed at an insertion angle in the range from 20 degrees to
70 degrees with relation to the flow of gas and powders; and
removing the agglomerates from the mixed phase container.
[0018] According to another aspect of the present invention, there
is provided a method for manufacturing an olefin polymer, said
method comprising: detecting agglomerates in a mixed phase
container by measuring strain in a detecting rod disposed in said
mixed phase container in which a mixed phase of gas and powders is
formed, wherein said detecting rod is disposed at an insertion
angle in the range from 20 degrees to 70 degrees with relation to
the flow of the gas and powders; and removing said agglomerates
from said mixed phase container.
[0019] The above and other objects, features, and advantages of the
present invention will be apparent from the following description
when taken in conjunction with the accompanying drawings which
illustrates preferred embodiments of the present invention by way
of example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic diagram showing a fluidized-bed olefin
polymerization reactor container and its peripheral pipelines,
according to an embodiment of the present invention;
[0021] FIG. 2 is an enlarged diagram showing the lower portion of
the fluidized-bed olefin polymerization reactor container according
to an embodiment of the present invention;
[0022] FIG. 3 is a plan view of the distributor plate in FIG.
2;
[0023] FIG. 4 is a side cross-sectional view of the detecting rod
in FIG. 2;
[0024] FIG. 5 is an enlarged cross-sectional view taken along a
line A-A in FIG. 4;
[0025] FIG. 6 is a graph showing the strain in the detecting rod in
relation to load acting on the rod;
[0026] FIG. 7 is a graph showing the amount of strain measured in
the detecting rod during an experiment in which the detecting rod
was disposed;
[0027] FIG. 8 is an explanatory diagram illustrating the insertion
angle of the detecting rod;
[0028] FIG. 9 is a graph showing the relationship between the
insertion angle and the colliding intensity (assuming that the
value at the insertion angle 0 of 90 degrees is 1.0);
[0029] FIG. 10 is a graph showing the relationship between the
insertion angle and the colliding intensity ratio of powders and
agglomerates; and
[0030] FIG. 11 is a graph showing the relationship between the
insertion angle and the accumulating span of agglomerates.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] An embodiment according to the present invention will be
described below with reference to the accompanying drawings. In
this embodiment, a fluidized-bed olefin polymerization reactor
container is used as a mixed phase container.
[0032] FIG. 1 is a schematic diagram showing a fluidized-bed olefin
polymerization reactor container and its peripheral pipelines. A
mixed phase of gas and powders is formed and fluidized in a
fluidized-bed olefin polymerization reactor container 1, which
serves as a mixed phase container. A polymerization reaction occurs
in such a state. The pressure in the fluidized-bed olefin
polymerization reactor container 1 is approximately in the range
from 1 to 3 MPa and the temperature approximately in the range from
70 to 100.degree. C.
[0033] A catalyst and an olefin gas such as ethylene gas are
supplied through an inlet 4 into the fluidized-bed olefin
polymerization reactor container 1. A circulating gas constantly
circulates via a gas line 7 by a circulating gas compressor 5. A
heat exchanger 6 is provided along the path of the circulating gas
for adjusting the temperature of the circulating gas.
[0034] A polymerization reaction occurred in the fluidized-bed
olefin polymerization reactor container 1 generates such products
as powdered polyethylene, polypropylene, or the like. These
products pass through a discharge valve 8 and a discharge line 9
into a primary silo 10, in which the products are stored
temporarily. The products are conveyed into nitrogen-compressor
line 13 by a rotary valve 11 and delivered to a desired location by
wind-force of nitrogen-compressor blower 12.
[0035] FIG. 2 is an enlarged diagram showing the lower portion of
the fluidized-bed olefin polymerization reactor container 1 with
part of the container 1 cut out to illustrate its internal
construction. The circulating gas supplied from the lower portion
of the fluidized-bed olefin polymerization reactor container 1
flows upward from a plurality of opening holes 21 formed on the
distributor plate 2 to form a mixed phase of gas and powders in the
fluidized-bed olefin polymerization reactor container 1, in which a
polymerization reaction occurs.
[0036] During this process, agglomerates 20 are formed in nodules
due to variations in the state of the mixed phase. The process of
this formation of agglomerates is not completely elucidated
yet.
[0037] While the formed agglomerates 20 remain small, agglomerates
circulate in the mixed phase in the floating state along with the
flow of powders in the mixed phase. As the agglomerates 20 grow
larger, however, agglomerates are no longer fluidized together with
the powders and begin to settle in the mixed phase. Such
agglomerates 20 generally accumulate near the distributor plate or
else move irregularly due to the force of the circulating gas
diffused from the opening holes on the distributor plate.
[0038] In order to move these large agglomerates 20 over the
distributor plate 2, the inventors gave directivity to the
circulating gas diffused from the opening holes 21, and developed a
distributor plate that forces the flow of gas and powders to move
over the distributor plate 2 in a circular direction by orienting
the opening holes 21 in the same circular direction (refer to
Japanese Laid-open Patent Application Publication No.5-136013). In
the present embodiment, this distributor plate is used as the
distributor plate 2.
[0039] As shown in FIG. 3, the opening holes 21 through which the
gas is diffused are formed in concentric circles on the distributor
plate 2, and streamlined caps 22 are disposed on top of the opening
holes 21. With this construction, the gas is diffused in a
horizontal direction from the opening holes 21 on the distributor
plate 2. In FIG. 3, the gas flows in the counterclockwise
direction.
[0040] Accordingly, the large agglomerates described above can be
moved in a specific circular direction (counterclockwise in FIG. 3)
along the gas flow over the distributor plate 2. As the behavior of
agglomerates within the mixed phase is dependent not only on the
size of the agglomerates but also on operating conditions, such as
rate of gas flow, it is possible to move even large agglomerates
with a high rate of gas flow.
[0041] As shown in FIG. 2, a detecting rod 50 is disposed inside
the fluidized-bed olefin polymerization reactor container 1, and
comprises an apparatus for detecting agglomerates 20 formed by the
adherence of each olefin polymer. The detecting rod 50 will be
described below in detail.
[0042] The detecting rod 50 is supported like a cantilever with one
end fixed to the side wall of the fluidized-bed olefin
polymerization reactor container 1 and the other projecting freely
into the reactor container 1. The detecting rod 50 is disposed at a
predetermined height above the distributor plate 2.
[0043] As shown in FIGS. 4 and 5, strain detecting means (strain
gauges) 60 are disposed at four locations, that is, at the top,
bottom, left, and right with the cross-section of the detecting rod
50. Output signals from each of the strain detecting means 60 are
inputted via a cable 16 into a converter 17 and converted to the
current signals ranging from 4 to 20 mA thereby. The signals are
transferred via a cable 18 into a recording warning device 19 to be
monitored.
[0044] As the agglomerates 20 circulate along with the mixed phase,
the agglomerates 20 collide with the detecting rod 50 to generate
strain. The strain detecting means 60 measure the amount and
frequency of the strain to detect the existence and size of the
agglomerates 20 in the reactor container.
[0045] More specifically, the strain gauges 60 are provided with
element wires having a resistance R, shown below.
R=.rho.l/d.sup.2
[0046] Here, .rho. is resistivity, l is the length of the element
wire, and d is the diameter of the element wire.
[0047] When agglomerates 20 collide with the detecting rod 50, the
detecting rod 50 expands and contracts, causing the lengths l of
the element wires in the strain gauges 60 to change. As a result,
the resistance R of the element wires also changes. Accordingly,
the degree to which agglomerates 20 are formed can be understood
from the amount of change detected in the resistance R. Further,
since the strain gauges 60 are disposed at four positions, that is,
at the top, bottom, left, and right with the cross-section of the
detecting rod 50, as described above, one of the detecting rods 50
can measure the strain, regardless of the direction in which the
agglomerates 20 collide with the detecting rod 50.
[0048] As described above, the detecting rod 50 is mounted in the
side of the fluidized-bed olefin polymerization reactor container 1
at a predetermined height above the distributor plate 2. This
predetermined height h (refer to FIG. 2) may be set at a height to
enable detection of agglomerates 20 of a size that can fit through
the discharge valve 8, for example, ranging from about 5 to about
15 cm.
[0049] FIG. 6 is a graph illustrating the relationship between the
load and the strain (displacement 6) when a load is applied on the
detecting rod 50. The horizontal axis represents the strain, while
the vertical axis represents the load. In a normal state, a certain
extent of the load is applied to the detecting rod 50 by the
swirling flow in the fluidized-bed olefin polymerization reactor
container 1, but the amount of the load is very small and the
detecting rod 50 is stable. As the load increases, the strain also
grows larger. The load can be determined based on the amount of
strain with reference to the graph in FIG. 6.
[0050] If agglomerates 20 are formed in the fluidized-bed olefin
polymerization reactor container 1 and collide with the detecting
rod 50, then the load on the detecting rod 50 increases abruptly
and the strain generated in the detecting rod 50 changes. It is
possible to detect both the existence and size of agglomerates by
the amount of this change in the strain.
[0051] FIG. 7 shows a result of an actual experiment in which the
detecting rod 50 was disposed at the insertion angle, that is, the
angle .theta. formed by the detecting rod 50 and the direction of
the swirling gas and powders (refer to FIG. 8), of 90 degrees, and
agglomerates 20 formed in the fluidized-bed olefin polymerization
reactor container 1 were detected. In FIG. 7, the horizontal axis
represents time (one graduation signifies 30 minutes), while the
vertical axis represents strain. As shown in the graph in FIG. 7,
after a certain time has elapsed, considerably large strains occur
in the detecting rod 50 at regular intervals of about 6 minutes.
Consequently, it indicates that agglomerates 20 have been formed in
the fluidized-bed olefin polymerization reactor container 1 and
that the agglomerates 20 circulate in the reactor container 1 with
a period of about 6 minutes.
[0052] In this way, the state of agglomerates 20 formed in the
fluidized-bed olefin polymerization reactor container 1 can be
detected by changes in the strain generated in the detecting rod
50. Further, the formation and the size of agglomerates 20 can be
detected by the magnitude and period of strains after sudden
change. Certainly, even if a distributor plate is used as described
above, powders or agglomerates may not move strictly horizontally,
but may move vertically as well. However, since the strain gauges
60 are disposed at four positions, as described above, it is still
possible to detect vertically moving powders or agglomerates.
[0053] FIG. 9 shows a comparison of colliding intensity (detection
sensitivity) when agglomerates 20 collide with the detecting rod 50
for various insertion angles .theta. of the detecting rod 50 using
a distributor plate as a distributor plate 2. FIG. 10 shows a
comparison of the ratio of powders colliding intensity to
agglomerate colliding intensity (equivalent to the resolution at
the time of detection) under the condition in FIG. 9.
[0054] FIG. 9 shows the ratio of colliding intensity when the
detecting rod 50 is at a given insertion angle .theta. to the
colliding intensity when the detecting rod 50 is inserted at an
insertion angle .theta. of 90 degrees (assuming that the value at
the insertion angle of 90 degrees is 1.0). From the graph shown in
FIG. 9, the insertion angle .theta. to obtain a colliding intensity
ratio of 30% or higher is approximately in the range from 20
degrees to 160 degrees. A certain level of detecting sensitivity
can be expected to be obtained within the above range.
[0055] In FIG. 10, the ratio of colliding intensity between powders
and agglomerates 20 represents the ratio of signal strength (S/N
ratio) of at a normal state (in which agglomerates are not
colliding with the detecting rod) to at a colliding state (in which
agglomerates are colliding with the detecting rod).
[0056] From two graphs shown in FIGS. 9 and 10, when a detecting
rod 50 is inserted at an insertion angle .theta. ranging from 20
degrees to 160 degrees, a certain level of detecting sensitivity
and resolution can be obtained.
[0057] However, data from the experiments also indicate that the
agglomerates 20 occasionally adhered to and accumulated on the part
of the detecting rod 50 facing with the flow. FIG. 11 shows the
ratio of the accumulating span to a ten-minute period for various
insertion angles .theta.. From the graph shown in FIG. 11, when
powders or agglomerates moves in circumferential direction near the
inner wall of the container, it can be seen that agglomerates 20
tend to accumulate on the part of the detecting rod 50 facing with
the flow if the insertion angle .theta. of the detecting rod 50 is
set within the range from 70 degrees to 170 degrees.
[0058] As described above, accumulation of the agglomerates 20
encourages further agglomeration to cause great obstruct of
fluidization even including a stop in production. Hence, it is
essential to avoid the state in which the rate of accumulation of
the agglomerates is particularly high. Specifically, it is
essential to avoid inserting the detecting rod 50 at an insertion
angle .theta. within the range from 70 degrees to 170 degrees.
[0059] As the results shown in FIGS. 9 through 11, in order to
achieve a certain level of sensitivity and resolution with low
accumulation of agglomerates 20, the insertion angle .theta. is
preferably set within the range from 20 degrees to 70 degrees, or
more preferably within the range from 25 degrees to 50 degrees.
[0060] When actually installing the detecting rod 50 in the reactor
container 1, the detecting rod 50 is inserted in a nozzle provided
diagonally on the outer wall of the reactor container 1. For
purposes of construction, the nozzle cannot be provided at an
extremely acute angle. From this viewpoint, 20 degrees, as
described above, is thought to be a desirable lower limit for the
insertion angle .theta..
EXAMPLE FOR COMPARISON
[0061] A titanium-type catalyst and an alkyl aluminum compound as a
co-catalyst were supplied into a gas-phase fluidized-bed olefin
polymerization reactor having a diameter of 0.5 meter in a mixed
gas atmosphere of ethylene, 1-butene, and hydrogen, and the mixed
phase was polymerized.
[0062] The detecting rod 50 was inserted at right angles, that is,
an insertion angle .theta. of 90 degrees, and an insertion length
of 10 centimeters at a position 8 centimeters above the distributor
plate 2. With this configuration, the production of olefin
copolymer powder was conducted. Two days after the beginning of
production, the first agglomerates were detected in the mixture.
One hour later, the mixed phase was not substantially fluidized and
the entire mixed phase began to solidify, forcing operations to be
shut down. Specifically, since agglomerates adhered to the
detecting rod, the mixed phase container was filled with
agglomerates as the reaction progressed.
EXAMPLE OF THE PRESENT EMBODIMENT
[0063] As in the above experiment, a titanium-type catalyst and an
alkyl aluminum compound as a co-catalyst were supplied into a
gas-phase fluidized-bed olefin polymerization reactor having a
diameter of 50 centimeters in a mixed gas atmosphere of ethylene,
1-butene, and hydrogen, and the mixed phase was polymerized.
[0064] In this experiment, however, the detecting rod 50 was
inserted at an insertion angle 0 of 30 degrees and an insertion
length of 10 centimeters at a position 8 centimeters above the
distributor plate 2. With this configuration, the production of
olefin copolymer powder was conducted. Three days after the
beginning of production, the first agglomerates were detected.
However, the agglomerates did not adhere to the detecting rod.
Accordingly, the formed agglomerates were discharged one after
another together with the product and production was allowed to
continue without any problem.
[0065] As described above, according to the present invention, the
detecting rod is disposed at an insertion angle ranging from 20
degrees to 70 degrees in relation to the flow of gas and powders.
Consequently, the opportunity that agglomerates adhere to the
detecting rod can be reduced to increase the sensitivity and
precision of detection. Accordingly, it is possible to reduce the
accumulation of agglomerates and perform a polymer reaction without
obstructing fluidization in the mixed phase container.
[0066] Further, according to the present invention, a distributor
plate is provided in the bottom of the mixed phase container to
force the gas to circulate in a horizontal direction. The detecting
rod positioned at a specified height above the distributor plate
enables to control the flow of gas and powders in the mixed phase
container and effectively to force agglomerates to collide with the
detecting rod. Accordingly, agglomerates can be detected with
greater sensitivity.
[0067] Although certain preferred embodiments of the present
invention have been shown and described in detail, it should be
understood that various changes and modifications may be made
therein without departing from the scope of the appended
claims.
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