U.S. patent application number 14/782842 was filed with the patent office on 2016-02-25 for gas slide heat exchanger.
This patent application is currently assigned to OUTOTEC (FINLAND) OY. The applicant listed for this patent is OUTOTEC (FINLAND) OY. Invention is credited to Dirk LOHRBERG, Andreas ORTH.
Application Number | 20160054064 14/782842 |
Document ID | / |
Family ID | 48092957 |
Filed Date | 2016-02-25 |
United States Patent
Application |
20160054064 |
Kind Code |
A1 |
LOHRBERG; Dirk ; et
al. |
February 25, 2016 |
GAS SLIDE HEAT EXCHANGER
Abstract
A heat exchanger (1) for treating bulk material comprises an
elongated pipe (2) having an inlet (3) for introducing the bulk
material at one end and an outlet (4) for withdrawing the bulk
material at the other end. A plurality of heat exchange tubes (5)
extends along the longitudinal direction of the pipe (2), and a
plurality of fluidization nozzles (9, 9a) for introducing a
fluidizing gas is provided at the bottom (10) of the pipe (2).
Inventors: |
LOHRBERG; Dirk; (Offenbach,
DE) ; ORTH; Andreas; (Friedrichsdorf, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OUTOTEC (FINLAND) OY |
Espoo |
|
FI |
|
|
Assignee: |
OUTOTEC (FINLAND) OY
Espoo
FI
|
Family ID: |
48092957 |
Appl. No.: |
14/782842 |
Filed: |
April 10, 2013 |
PCT Filed: |
April 10, 2013 |
PCT NO: |
PCT/EP2013/057491 |
371 Date: |
October 7, 2015 |
Current U.S.
Class: |
62/374 |
Current CPC
Class: |
F28D 7/106 20130101;
F28D 7/16 20130101; F28D 7/0041 20130101; F28C 3/16 20130101; F28D
13/00 20130101; F28C 3/14 20130101 |
International
Class: |
F28C 3/14 20060101
F28C003/14; F28C 3/16 20060101 F28C003/16 |
Claims
1-13. (canceled)
14. Heat exchanger for treating bulk material comprising an
elongated pipe having an inlet for introducing the bulk material at
one end and an outlet for withdrawing the bulk material at the
other end, wherein a plurality of heat exchange tubes extends along
the longitudinal direction of the pipe, wherein a plurality of
fluidization nozzles for introducing a fluidizing gas is provided
at the bottom of the pipe, wherein at least some of the
fluidization nozzles extend from the bottom of the pipe into the
upper region of the pipe.
15. Heat exchanger according to claim 14, wherein the fluidization
nozzles are directed perpendicular to the conveying direction of
the bulk material.
16. Heat exchanger according to claim 14, wherein the pipe is
tilted downwards in the conveying direction of the bulk material,
preferably at an angle of 5 to 10.degree..
17. Heat exchanger according to claim 14, wherein the pipe
comprises a double wall for receiving a heat exchange medium.
18. Heat exchanger according to claim 14, wherein the pipe is
formed by a plurality of smaller pipes for receiving a heat
exchange medium.
19. Heat exchanger according to claim 14, wherein transport nozzles
enter into the pipe at a location distanced from the bottom of the
pipe, preferably by about 25 to 75% of the height of the pipe.
20. Heat exchanger according to claim 19, wherein the transport
nozzles are inclined downwards at an angle of 30 to 60.degree..
21. Heat exchanger according to claim 19, wherein the transport
nozzles are inclined in the conveying direction of the bulk
material.
22. Heat exchanger according to claim 14, wherein the fluidization
and/or transport nozzles are located in respective rows along the
longitudinal direction of the pipe.
23. Heat exchanger according to claim 22, wherein common supply
pipes are provided for supplying fluidizing gas to each row of
nozzles.
24. Heat exchanger according to claim 14, wherein the flow rate of
the fluidization and/or transport nozzles can be regulated.
25. Heat exchanger according to claim 14, wherein a heat exchange
medium is directed counter-currently or co-currently to the
conveying direction of the bulk material.
Description
[0001] The invention relates to a gas slide heat exchanger for
treating bulk material comprising an elongated pipe having an inlet
for introducing the bulk material at one end and an outlet for
withdrawing the bulk material at the other end.
[0002] In plant engineering, bulk material often has to be conveyed
and cooled or heated at the same time. For this purpose screw
conveyors are known as described in document DE 15 51 441. Such a
heat exchanger comprises a stationary elongated housing having an
inlet for the material to be treated at one end and an outlet at
the other end as well as one or more screw rotors provided in the
housing and extending along the length thereof. The rotor comprises
a central shaft and a worm gear provided on the outer surface of
the shaft. Within the shaft a conduit is provided which is
connected to a steam supply. The bulk material is introduced
through the inlet into the housing and conveyed therethrough by the
rotating movement of the screw conveyor. At the same time the bulk
material is heated by the steam flowing in the central conduit of
the shaft as well as by steam flowing in the double wall of the
housing.
[0003] Another heat exchanger comprising a screw conveyor is known
from document DE 534 988, wherein a heating or cooling medium flows
through the hollow screw conveyor to heat or cool the bulk material
transported through the housing. Other screw conveying heat
exchangers are known from documents DE 17 51 961 or DD 288 663
A5.
[0004] The design of screw conveyors is complex and cost intensive.
Further, the conveyors require a separate drive and are limited in
length due to bearing and torque impacts.
[0005] It is also been known to perform the heat exchange in a
fluidized bed. Document AT 507 100 B1 describes a process and
apparatus for heat exchange wherein a bulk material is fluidized by
introducing a fluidizing gas and wherein the bulk material is
additionally agitated by a stirrer. Stirring arms are rotated
between layers of heat exchange tubes provided in horizontal planes
within the housing.
[0006] Document DE 10 2011 078 954 A1 describes another bulk heat
exchange apparatus having a feed section, a heat exchanger section
and a bulk material discharge section. The bulk material feed
section is divided by a bulk partition in a conveyor flow supply
chamber and a counter flow supply chamber. The bulk material
partition continues to the bulk heat exchanger section. Thereby, a
conveyor flow region and a counter flow region are formed of the
heat exchanger section. After passing through the heat exchanging
section, the heated particles are circulated within an upper
chamber of the apparatus and fall back into an annular bed to be
withdrawn. This system also is quite complex and requires a
specific regulation of the fluidization air.
[0007] In common gas slides without heat exchanging elements as
known e.g. from WO 2010/147771 A, fluidizing gas is injected via
nozzles or membranes at the lower part of the gas slide. The amount
of injected gas is kept in a range that the bulk material is
flowing but not expanding or circulating as it is desired for
example in a fluidized bed cooler.
[0008] It is the object of the present invention to provide a gas
slide heat exchanger with improved heat exchange capabilities and
an easy structure.
[0009] According to the invention there is provided a heat
exchanger comprising the features of claim 1. A plurality of heat
exchange tubes extends along the longitudinal direction of the
pipe, wherein a plurality of fluidization nozzles for introducing a
fluidizing gas is provided at the bottom of the pipe. The bulk
material is fluidized and slowly flows along the elongated pipe. At
the same time heat is exchanged with the heat exchange medium
flowing through the heat exchanging tubes. In comparison to a screw
conveyor the heat exchanger elements of the gas slide heat
exchanger according to the present invention can be designed with a
greater surface/volume ratio. Multiple single heat exchange tubes
can be integrated to a bundle with a much greater surface than the
cylindrical surface of the screw shaft and the screw conveyor
casing used in the prior art. Simultaneously, the heat exchange is
promoted by the expanded surface of the bulk material fluidized by
the fluidizing gas. This is not possible in the standard screw
conveyor.
[0010] In a preferred embodiment of the invention, the fluidization
nozzles are directed perpendicular to the conveying direction of
the bulk material. Thereby, it is ensured that the bulk material is
sufficiently fluidized when passing the nozzles. "Perpendicular" in
the context of the present invention refers to an orientation of
the fluidization nozzles within a range of 85 to 95.degree., in
particular about 90.degree., relative to the major conveying
direction of the bulk material along the pipe.
[0011] If some of the fluidization nozzles extend from the bottom
of the pipe into the upper region of the pipe, it is possible to
ensure the expansion and conveying of the material also in cases of
bulk material that tends to generate holes rather than expand when
fluidized. This happens in particular if the bulk material is very
fine.
[0012] Preferably, the pipe is tilted downwards in the conveying
direction of the bulk material, preferably at an angle of 5 to 10
degrees or more preferably at an angle of 6 to 8 degrees. In such a
pipe, the fluidized bulk material automatically flows down the pipe
towards the outlet.
[0013] In order to increase the heat exchange within the heat
exchanger, the pipe preferably comprises a double wall for
receiving a heat exchange medium. Accordingly, heat is exchanged
not only between the longitudinal heat exchange tubes within the
fluidized material but also from the outer wall.
[0014] In a further embodiment, the pipe wall may be formed from a
plurality of smaller pipes for receiving a heat exchange medium.
Thereby, the heat exchange surface is increased. In addition or
alternatively, a plurality of smaller pipes may be provided within
the pipe for receiving the heat exchange medium.
[0015] In order to promote the transport of the bulk material
through the pipe, it is within the scope of the present invention
to provide transport nozzles which enter into the pipe at a
location distanced from the bottom of the pipe to introduce
additional transport gas. Preferably, the openings of the transport
nozzles are located in a region extending between about 25 and 75%
of the height of the pipe.
[0016] According to an embodiment of the invention, the transport
nozzles are inclined downwards at an angle of 30 to 60.degree.,
preferably 40 to 50.degree. and in particular about 45.degree..
[0017] In addition, the invention provides that the transport
nozzles are inclined in the conveying direction of the bulk
material in order to promote the conveyance of the material.
Usually, the transport nozzles are inclined at an angle of 30 to
60.degree., preferably 40 to 50.degree. and in particular about
45.degree..
[0018] According to an aspect of the present invention, the
fluidization and/or transport nozzles are located in respective
rows along the longitudinal direction of the pipe, wherein
preferably common supply pipes are provided for supplying
fluidizing gas to each row of nozzles.
[0019] According to the invention, the flow rate of the
fluidization and/or transport nozzles can be regulated, wherein
preferably the fluidizing gas is injected through the transport
nozzles with a low velocity in conveying direction to ensure just a
proper bulk material flow.
[0020] The other part of the fluidizing gas can instead be injected
perpendicular to the conveying direction through the fluidization
nozzles with a comparatively higher velocity obtaining an expansion
of the bulk material and hence a great material surface and
improved heat exchange.
[0021] The heat exchange medium may be directed counter-currently
or co-currently to the conveying direction of the bulk material
depending on the specific needs of the process and material.
[0022] The invention will now be described in more detail on the
basis of preferred embodiments and the drawing. All features
described and/or illustrated form the subject matter of the
invention per se or in any combination, independent of their
inclusion in individual claims or their back reference.
[0023] In the drawing:
[0024] FIG. 1 is a cross section of a heat exchanger according to
the present invention,
[0025] FIG. 2 is a cross section of a first embodiment taken along
line A-A in FIG. 1;
[0026] FIG. 3 is a cross section of the first embodiment of the
invention wherein the heat exchange tubes are not shown, while the
distribution of the bulk material within the pipe cross section is
shown;
[0027] FIG. 4 is a cross section similar to FIG. 3 of a second
embodiment of the invention taken along line A-A in FIG. 1;
[0028] FIG. 5 is a cross section similar to FIG. 3 of an
alternative embodiment of the present invention taken along line
A-A in FIG. 1.
[0029] A gas slide heat exchanger 1 according to the present
invention as shown in FIG. 1 includes a pipe 2 having an inlet 3
for introducing a bulk material at a first end, and an outlet 4 for
withdrawing the bulk material at the other end of pipe 2. The pipe
2 is slightly downwards tilted at an angle of 6 to 8 degrees in the
direction of the outlet 4. A plurality of heat exchange tubes 5
(FIG. 2) extends along the longitudinal direction of pipe 2. A
heating medium is introduced into the heat exchange tubes 5 via a
supply port 6 and withdrawn through outlet port 7 at the other end
of pipe 2. The wall 2a of pipe 2 is designed as a double wall to
receive additional heat exchange medium.
[0030] In the embodiment shown in FIG. 1, the heat exchanging
medium, preferably water, boiler feed water or thermo oil, is
directed counter-currently to the flow of the bulk material. In an
alternative embodiment, the heat exchange medium can just as well
be directed co-currently to the conveying direction of the bulk
material in accordance with the specific requirements of the heat
exchange process and the material to be treated.
[0031] Below the pipe 2 a supply pipe 8 for fluidizing gas is
provided. From said supply pipe 8 a plurality of fluidization
nozzles 9 extends in an upward direction towards pipe 2. As evident
from FIG. 2, the fluidization nozzles 9 enter the pipe 2 at its
bottom 10 at approximately the center of the bottom region of pipe
2.
[0032] Further, supply pipes 11, 12 extend along the major part of
the length of pipe 2 and comprise transport nozzles 13, 14 which
enter into pipe 2 in a region located at 25 to 75%, in particular
30 to 40% of the height of pipe 2. As evident from FIG. 2, the
transport nozzles 13, 14 are inclined downwards at an angle of
approximately 45.degree.: As evident from FIG. 1, the transport
nozzles 13, 14 further are inclined in the conveying direction of
the bulk material at an angle of also about 45.degree.. The
fluidization gas, in particular air, that is introduced
(continuously or as a pulsed stream) into the pipe 2 through the
fluidization nozzles 9 and the transport nozzles 13, 14 fluidizes
the bulk material within pipe 2 and flows together with the bulk
material along pipe 2 until it exits through a gas outlet 15
provided at the end of pipe 2.
[0033] The heat exchanger according to the first embodiment of the
present invention as shown in FIGS. 1 and 2 is basically
constructed as described above. Next, its operation and advantages
shall be described.
[0034] Bulk material, such as ore fines, aluminium hydrate, ash or
the like, is introduced into pipe 2 through inlet 3. The bulk
material is fluidized within pipe 2 by fluidization gas introduced
through the fluidization nozzles 9 and the transport nozzles 13, 14
and flows along pipe 2 until it is withdrawn from pipe 2 through
outlet 4. A part of the fluidizing gas is injected with a low
velocity in conveying direction through the transport nozzles 13,
14, while the other part of the fluidizing gas is injected with a
comparatively higher velocity through the fluidization nozzles 9 in
a direction perpendicular to the conveying direction of the bulk
material. Thereby, the bulk material is fluidized and expanded to
obtain a great material surface and an improved heat exchange. The
velocities of the fluidizing gas introduced through the transport
nozzles 13, 14 and the fluidization nozzles 9, respectively, depend
on the grain size and other properties of the bulk material. If the
bulk material is fluidizable, the velocity of the fluidizing gas
introduced through the fluidization nozzle 9 is typically smaller
than 0.2 m/s (related to the longitudinal cross section) In case
the bulk material is not fluidizable, e.g. because it is too fine
or too heavy, and the transport mechanism is not based on gravity
flow, the amount of fluidizing gas introduced through the transport
nozzles 13, 14 is higher than the amount of fluidizing gas
introduced through nozzle 9.
[0035] The concept of the fluidization is illustrated in FIG. 3
wherein the bulk material is primarily transported in transport
zone 20 while zone 21 indicates an area with enlarged material
surface due to the expansion of the bulk material. For the sake of
convenience, the heat exchanging tubes 5 are not illustrated in
FIGS. 3 to 5.
[0036] In particular for bulk material that tends to generate holes
upon the introduction of fluidization gas rather than to expand,
FIG. 4 shows an embodiment, wherein the transport nozzles 13, 14
are arranged at a higher region of the pipe 2 so that an increased
zone 21 with enlarged material surface is created. A similar effect
is achieved in the embodiment shown in FIG. 5 if some of the
fluidization nozzles 9a do not open at the bottom 10 of pipe 2 but
extend into the upper region of the pipe 2 to create a zone 21 with
enlarged material surface. The transport nozzles 13, 14 and the
extended fluidization nozzles 9a may be combined in a heat
exchanger 1.
[0037] The flow rate of the fluidization air supplied through
fluidization nozzles 9, 9a and transport nozzles 13, 14 can be
regulated in order to provide for adequate fluidization and
transport conditions of the bulk material within pipe 2.
[0038] Based on information of screw conveyor suppliers and
operation experience with fluidized bed coolers, it can be assumed
that the heat transport can be approximately quadrupled using a gas
slide heat exchanger according to the present invention instead of
the standard screw conveyor. This is possible by expanding the bulk
material in a range that can be reasonably realized in a gas slide
heat exchanger.
[0039] In comparison with a screw conveyor a gas slide heat
exchanger according to the present invention is less complex to
manufacture, provides a greater heat exchange surface at
approximately same main dimensions and provides for an improved
heat transfer due to an expanded bulk material surface.
[0040] The present invention is suitable for heating the bulk
material by employing heated heat exchange media, but may also be
used for cooling the bulk material with cold heat exchange
media.
LIST OF REFERENCE NUMBERS
[0041] 1 heat exchanger [0042] 2 pipe [0043] 2a double wall [0044]
3 inlet [0045] 4 outlet [0046] 5 heat exchange tube [0047] 6 supply
port [0048] 7 outlet port [0049] 8 supply pipe [0050] 9, 9a
fluidization nozzle [0051] 10 bottom [0052] 11, 12 supply pipe
[0053] 13, 14 transport nozzle [0054] 15 gas outlet [0055] 20
transport zone [0056] 21 zone with enlarged bulk material surface
[0057] 22 bulk material level (without fluidization)
* * * * *