EA029071B1 - Heat exchanger with fluidized bed - Google Patents

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).

Description

The invention relates to a gas glide heat exchanger (and da§ δΐίάβ Nea1 exsnapsg) for treating bulk material, comprising an elongated pipe having an inlet for introducing bulk material at one end and an outlet for removing loose material at the other end.

In industrial equipment, bulk material often needs to be moved while being cooled or heated. For this purpose, known screw conveyors are used, as described in document No. 1551441. This heat exchanger includes a fixed elongated body having an inlet for the material to be processed at one end and an outlet at the other end, as well as one or more helical rotors provided in the body and passing along its length. The rotor includes a central shaft and a worm gear on the outer surface of the shaft. A pipeline is provided inside the shaft that is connected to a steam source. Bulk material is injected through the inlet opening into the body and is moved through it through the rotational movement of the screw conveyor. At the same time, the bulk material is heated by steam flowing in the central tube of the shaft, as well as steam flowing in the double wall of the housing.

Another heat exchanger, including a screw conveyor, is described in document No. 534988, in which a heating or cooling medium flows through a hollow auger conveyor to heat or cool bulk material transported through the housing. Other heat exchangers with a screw conveyor are described in documents ΌΕ 1751961 or 288663 A5.

The design of screw conveyors is complex and expensive. In addition, conveyors require a separate drive and are limited in length due to the need for support and the effect of torque.

It is also known the implementation of heat transfer in the fluidized bed. The document АТ 507100 В1 describes a method and a device for heat exchange, where the bulk material is fluidized by introducing a fluidizing gas and where the bulk material is additionally mixed with an agitator.

The blades of the stirrer rotate between layers of heat exchange tubes located in horizontal planes inside the housing.

Document No. 102011078954 A1 describes another heat exchanger for bulk material, having a supply section, a heat exchange section and a discharge section for bulk material. The bulk material supply section is divided by a partition into a direct-flow chamber and a counter-flow chamber. Partition for bulk material continues to the heat exchange section of the bulk material. Thus, the direct-flow and counter-current regions are formed by a heat exchange section. After passing through the heat exchange section, the heated particles circulate within the upper chamber of the device and fall back into the ring layer, from where they should be removed. This system is also quite complex and requires special regulation of the fluidizing air.

In conventional gas slide devices without heat exchange elements, such as the device known from 2010/147771 A, fluidizing gas is introduced through nozzles or membranes at the bottom of the gas slip device. The amount of introduced gas is maintained in such a range that the bulk material flows, but does not expand or circulate, as desired, for example, in a fluidized bed cooler.

The object of the present invention is to provide a gas glide heat exchanger with improved heat exchange characteristics and a simple structure.

According to the present invention proposed heat exchanger, the distinctive features of which are listed in claim 1 of the claims. A plurality of heat exchange tubes extend along the longitudinal direction of the tube, and a plurality of nozzles are provided for introducing a fluidizing gas at the bottom of the tube. Bulk material is fluidized, and it slowly flows along an elongated pipe. At the same time, heat exchange takes place with the heat exchange medium flowing through the heat exchange tubes. Compared to the screw conveyor, the heat exchange elements of the gas-exchanging heat exchanger of the present invention can be designed with a much larger surface / volume ratio. Many single heat exchange tubes can be integrated into a bundle with a much larger surface than the cylindrical surface of the screw shaft and the screw conveyor housing, which are used in the prior art. At the same time, heat transfer is facilitated by the increased surface of the bulk material fluidized by a fluidizing gas. This is not possible with a standard screw conveyor.

In the preferred embodiment of the present invention, fluidizing nozzles are directed perpendicular to the direction of movement of the bulk material. Thus provide sufficient fluidization of the bulk material as it passes by the nozzles. Perpendicular in the context of the present invention refers to the orientation of the fluidizing nozzles at an angle in the range from 85 to 95 °, in particular about 90 ° relative to the main direction of movement of the bulk material along the pipe.

If some of the fluidizing nozzles pass from the lower part of the pipe to the upper area of the pipe, then material can be expanded and moved also in the case of bulk material that tends to form holes rather than expand when it is fluidized. it

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occurs, in particular, if the bulk material is very fine.

Preferably, the pipe is inclined downward in the direction of movement of the bulk material, preferably at an angle of from 5 to 10 ° or more preferably at an angle of from 6 to 8 °. In such a pipe, the fluidized bulk material automatically flows down the pipe towards the outlet.

To increase heat transfer inside the heat exchanger, the pipe preferably includes a double wall for receiving a heat exchange medium. Accordingly, heat exchange occurs not only with longitudinal heat exchange tubes inside the fluidized material, but also with the outer wall.

In another embodiment, the pipe wall may be formed from a plurality of smaller tubes for receiving a heat exchange medium. Thus increase the heat exchange surface. In addition or alternatively, a plurality of smaller tubes may be provided inside the tube to receive the heat exchange medium.

To facilitate the transport of bulk material through a pipe, transport nozzles are provided in the present invention for introducing additional carrier gas that enters the pipe at some distance from the bottom of the pipe. Preferably, the openings of the transport nozzles are in an area located between about 25 and 75% of the height of the pipe.

According to one embodiment of the present invention, the transport nozzles are inclined downward at an angle of from 30 to 60 °, preferably from 40 to 50 °, in particular about 45 °.

In addition, the present invention provides that the transport nozzles are inclined in the direction of movement of the bulk material in order to facilitate the transport of the material. Usually transport nozzles are inclined at an angle of from 30 to 60 °, preferably from 40 to 50 °, in particular about 45 °.

According to one aspect of the present invention, fluidizing and / or transport nozzles are arranged in respective rows along the longitudinal direction of the pipe, with common feed pipes preferably provided for supplying a fluidizing gas to each row of nozzles.

According to the present invention, the flow rate in the fluidizing and / or transport nozzles can be controlled, and preferably a fluidizing gas is introduced through the transport nozzles at a low speed in the direction of travel to ensure an appropriate flow rate of the bulk material.

Another part of the fluidizing gas, on the contrary, can be introduced perpendicular to the direction of movement through fluidizing nozzles at a relatively higher speed, obtaining an expansion of the bulk material and, therefore, an increase in the surface of the material and an improvement in heat transfer.

The heat exchange medium may be directed countercurrent or downstream with respect to the direction of movement of the bulk material, depending on the specific requirements of the method and material.

The present invention will now be described in more detail based on the preferred embodiments and drawings. All described and / or illustrated features form the subject matter of the present invention by themselves or in any combination, regardless of their inclusion in the individual claims or backlinks to them.

Brief Description of the Drawings

FIG. 1 is a cross section of a heat exchanger in accordance with the present invention;

FIG. 2 is a cross section of a heat exchanger in accordance with a first embodiment of the invention, taken along line A-A in FIG. one;

FIG. 3 is a cross section of a heat exchanger in accordance with a first embodiment of the invention, where the heat exchange tubes are not shown, while the distribution of the bulk material inside the tube (in cross section) is shown;

FIG. 4 is a cross section of a heat exchanger in accordance with a second embodiment of the invention, taken along line A-A in FIG. 1, similar to that shown in FIG. 3;

FIG. 5 is a cross section of a heat exchanger in accordance with an alternative embodiment of the invention, taken along line A-A in FIG. 1, similar to that shown in FIG. 3

A gas glide heat exchanger 1 according to the present invention, as shown in FIG. 1 includes a pipe 2 having an inlet 3 for introducing bulk material at the first end and an outlet 4 for removing bulk material at the other end of pipe 2. The pipe 2 is slightly tilted down at an angle of 6 to 8 ° in the direction of the outlet 4. Set heat exchange tubes 5 (Fig. 2) passes along the longitudinal direction of the pipe 2. Heat exchange medium is introduced into the heat exchange tubes 5 through the inlet 6 and out through the outlet 7 at the other end of the pipe 2. The wall 2a of the pipe 2 is made in the form of a double wall for EMA additional heat exchange medium.

In the embodiment depicted in FIG. 1, the heat exchange medium, preferably water, make-up water for the boiler or thermal oil, is directed in countercurrent to the flow of bulk material. In an alternative embodiment, the heat exchange medium can also be directed downstream with respect to the direction of movement of the bulk material, depending on the specific requirements.

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heat exchange process and material to be processed.

Below pipe 2 there is a supply pipe 8 for fluidizing gas. From said supply pipe 8, a plurality of fluidizing nozzles 9 extend upwardly towards pipe 2. As can be seen from FIG. 2, fluidizing nozzles 9 enter the pipe 2 in its lower part 10 approximately in the center of the lower region of the pipe 2.

In addition, along most of the length of the pipe 2, feed pipes 11, 12 pass through, including transport nozzles 13, 14, which enter pipe 2 in an area located at a height of from 25 to 75%, in particular from 30 to 40% of the height of the pipe 2. As can be seen from FIG. 2, the transport nozzles 13, 14 are inclined downward at an angle of approximately 45 °. As can be seen from FIG. 1, the transport nozzles 13, 14 are also inclined in the direction of movement of the bulk material at an angle of also about 45 °. The fluidizing gas, in particular air, which is introduced (continuously or in a pulsed mode) into pipe 2 through fluidizing nozzles 9 and transport nozzles 13, 14, fluidizes the bulk material inside pipe 2 and flows along with the bulk material along pipe 2 until it exits through the outlet 15 for gas, provided at the end of the pipe 2.

The heat exchanger according to the first embodiment of the present invention, as shown in FIG. 1 and 2, mainly constructed as described above. Next will be described his work and benefits.

Bulk material, such as fine ore, aluminum hydroxide, ash, etc., is introduced into pipe 2 through inlet 3. Bulk material is fluidized inside pipe 2 by fluidizing gas, which is introduced through fluidizing nozzles 9 and transport nozzles 13, 14 and it flows along pipe 2 until it is taken out of pipe 2 through outlet 4. Part of the fluidizing gas is injected at a low speed through the transport nozzles 13, 14 in the direction of movement, while another part of the fluidizing gas is injected with a relatively higher by speed through fluidizing nozzles 9 in the direction perpendicular to the direction of movement of the bulk material. Thus, the bulk material is fluidized and expanded to form a large material surface to improve heat transfer. The velocity of the fluidizing gas, which is introduced through the transport nozzles 13, 14 and fluidizing nozzles 9, respectively, depends on the grain size and other properties of the bulk material. If the bulk material is fluidizable, the velocity of the fluidizing gas that is introduced through the fluidizing nozzle 9 is generally less than 0.2 m / s (relative to the longitudinal section). In the case when the bulk material cannot fluidize, for example, because it is too fine or too heavy, and the transport mechanism is not based on flow under the action of gravity, then the amount of fluidizing gas introduced through the transport nozzles 13, 14 is more than the amount of fluidizing gas introduced through the nozzle 9.

The concept of fluidization is shown in FIG. 3, where the bulk material is mainly transported in the transport zone 20, while zone 21 indicates an area with an enlarged surface of the material due to expansion of the bulk material. For convenience, the heat exchange tubes 5 are not shown in FIG. 3-5

In particular, for bulk material, which tends to form holes when introducing a fluidizing gas, rather than expanding, FIG. 4 shows an embodiment where the transport nozzles 13, 14 are located in the higher region of the pipe 2 so as to cause an increase in the area 21 with an enlarged surface of the material. A similar effect is achieved in the embodiment shown in FIG. 5, if some of the fluidizing nozzles 9a are not open in the lower part 10 of the pipe 2, but pass into the upper area of the pipe 2, creating an area 21 with an enlarged surface of the material. Transport nozzles 13, 14 and elongated fluidizing nozzles 9a may be combined in a heat exchanger 1.

The flow rate of the fluidizing air that is supplied through the fluidizing nozzles 9, 9a and the transport nozzles 13, 14 can be adjusted to ensure sufficient fluidization and create suitable conditions for transporting bulk material inside the pipe 2.

Based on information from suppliers of screw conveyors and operating experience of fluidized bed coolers, it can be assumed that when using a heat exchanger with a gas slide according to the present invention, the heat transfer can be about four times more than a standard screw conveyor. This is made possible by expanding the bulk material in a range that can reasonably be implemented in a gas-exchanged heat exchanger.

Compared to the screw conveyor, the gas-slid heat exchanger of the present invention is less complex to manufacture, provides a large heat exchange surface area with approximately the same overall dimensions, and provides improved heat transfer due to the increased surface of the bulk material.

The present invention is suitable for heating a bulk material using a heated heat exchange medium, but can also be used to cool the bulk material using a cooled heat exchange medium.

List of item numbers in the drawings.

1 - Heat exchanger

2 - pipe

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2a is a double wall,

3 - inlet,

4 - outlet,

5 - heat exchange tube,

6 - inlet,

7 - outlet,

8 - feed pipe

9, 9a - fluidizing nozzle,

10 - the lower part

11.12 - feed pipe,

13, 14 - transport nozzle,

15 - outlet for gas,

20 - transport zone

21 - zone with an increased surface of the bulk material,

22 - the level of bulk material (without fluidization).

Claims (12)

CLAIM 1. A heat exchanger (1) for treating bulk material, comprising a horizontally oriented elongated pipe (2), having an inlet (3) for introducing bulk material at one end and an outlet hole (4) for removing bulk material at the other end, in which heat exchange tubes (5) extend in the longitudinal direction of the tube (2), while in the lower part (10) of the tube (2) nozzles (9, 9a) are provided to create a fluidized bed of bulk material by introducing a fluidizing gas, which distinguishes By the fact that at least some of the nozzles (9a) extend from the lower part (10) of the pipe (2) into the upper area of the pipe (2). 2. The heat exchanger according to claim 1, characterized in that the nozzles (9, 9a) for creating a fluidized bed are directed perpendicular to the direction of movement of the bulk material. 3. The heat exchanger according to claim 1 or 2, characterized in that the pipe (2) is inclined downward in the direction of movement of the bulk material, preferably at an angle of from 5 to 10 °. 4. A heat exchanger according to any one of the preceding claims 1 to 3, characterized in that the pipe (2) includes a double wall (2a) for receiving an additional heat exchange medium. 5. A heat exchanger according to any one of the preceding claims 1-4, characterized in that the tube (2) is formed by a plurality of smaller tubes for receiving a heat exchange medium. 6. A heat exchanger according to any one of the preceding claims 1-5, characterized in that transport nozzles (13, 14) enter the pipe (2) for introducing an additional transport gas at a distance from the lower part (10) of the pipe (2), which is preferably from about 25 to 75% of the height of the pipe (2). 7. A heat exchanger according to claim 6, characterized in that the transport nozzles (13, 14) are inclined downward at an angle of from 30 to 60 °. 8. Heat exchanger according to claim 6 or 7, characterized in that the transport nozzles (13, 14) are inclined in the direction of movement of the bulk material. 9. A heat exchanger according to any one of the preceding claims 1 to 8, characterized in that the nozzles (9, 9a) for creating a fluidized bed and / or transport nozzles (13, 14) are located in the respective rows along the longitudinal direction of the pipe (2). 10. The heat exchanger according to claim 9, characterized in that the common supply pipes (11, 12) are provided for supplying a fluidizing gas to each row of nozzles (9, 9a, 13, 14). 11. The heat exchanger according to any one of the preceding claims 1-10, characterized in that the flow rate in the nozzles (9, 9a) to create a fluidizing layer and / or transport nozzles (13, 14) can be adjusted. 12. A heat exchanger according to any one of the preceding claims 1 to 11, characterized in that the heat exchange medium is directed in countercurrent or downstream with respect to the direction of movement of the bulk material.