Cross-flow heat exchanger for the thermal treatment of granular materials

Description

[0001] The invention relates to a cross-flow heat exchanger for the thermal treatment of semolina and / or granular materials according to the preamble of claim 1.

[0002] A heat exchanger is a device that transfers thermal energy from one material stream to another. Such heat exchangers are used, for example, in process engineering plants and can be designed as cross-flow heat exchangers.

[0003] Cross-flow heat exchangers perform thermal treatment of powdered and / or granular materials. Such a cross-flow heat exchanger is found, for example, in a recycling plant that processes contaminated bulk material (e.g., granules) so that it can be used as starting material for a new product in subsequent manufacturing or processing processes.

[0004] The cross-flow heat exchanger typically consists of a process chamber through which the granules to be tempered are conveyed vertically. The process chamber has side nozzles through which an air stream is introduced into the process chamber. The air stream flows around the granules to be tempered and exits the process chamber on the opposite side.

[0005] EP 1 019 663 A1 discloses a dryer heat exchanger for the thermal treatment of granular bulk materials. The heat exchanger essentially consists of a housing with a channel with air-permeable

[0006] Sheets through which the bulk material is passed. Several nozzles for the inlet and outlet of the process gas are located on the side of the housing. The dryer heat exchanger's design is very complex due to the divided chamber and the numerous lateral nozzles. This makes it difficult to control the movement of the granulate within the channel. Furthermore, the interior of the heat exchanger is difficult to clean.

[0007] US 4 424 634 A discloses a cross-flow heat exchanger according to the preamble of claim 1.

[0008] The object of the present invention is to design a cross-flow heat exchanger that is simpler in design, performs more efficient thermal treatment, and is easier to clean. Furthermore, the cross-flow heat exchanger should allow for better control of the granulate movement.

[0009] To achieve the stated object, the invention is characterized by the technical teaching of claim 1.

[0010] An essential feature of the invention is that the cross-flow heat exchanger has an air inlet chamber with a chamber housing on the air inlet side, which is closed on one side with a perforated plate, and an air outlet chamber with a chamber housing on the air outlet side, which is closed on one side with a sieve.

[0011] The cross-flow heat exchanger consists of a housing with a process chamber. The housing has a material inlet and a material outlet for the granular material. The granular material moves from top to bottom within the process chamber and preferably has a fixed bed configuration. A gas stream flows through the process chamber. The gas stream is introduced via an air inlet chamber, flows through or around the granular material, and is discharged from the process chamber via an air outlet chamber.

[0012] The air inlet chamber and / or the air outlet chamber are detachably mounted on the housing of the cross-flow heat exchanger. This detachable design allows the air inlet chamber and the air outlet chamber to be removed from the housing and easily cleaned. Furthermore, by separating the air inlet and / or air outlet chamber, the process chamber is freely accessible and can also be easily cleaned.

[0013] The air inlet chamber and / or the air outlet chamber essentially consist of a chamber housing that forms a receptacle for a perforated plate or a sieve. Preferably, the perforated plate and / or the sieve are detachably connected to the air inlet chamber and / or the air outlet chamber.

[0014] The chamber housing is preferably box-shaped or cylindrical and closed on one side by a perforated plate or a sieve. The chamber housing thus has a chamber volume for accommodating a specific amount of the tempered gas, with the gas flowing out of the chamber housing of the air inlet chamber through openings in the perforated plate and flowing into the chamber housing of the air outlet chamber through gaps in the sieve.

[0015] The perforated plate and / or the screen can be constructed in one or more parts. Furthermore, the perforated plate and the screen can have any geometric shape and dimensions. The crucial point is that the perforated plate and the screen can be arranged in the chamber housing of the air inlet and outlet chambers.

[0016] The air inlet chamber features a perforated plate that forms an air-permeable partition between the chamber housing of the air inlet chamber and the process chamber. The arrangement of a perforated plate on the air inlet side has the significant advantage of being simple in design and therefore relatively inexpensive. The perforated plate only needs to be air-permeable to allow the gas stream to enter the process chamber.

[0017] The perforated plate has several air-permeable openings. The openings are preferably designed such that the gas flow flowing through the piping into the air inlet chamber forms a certain backpressure and is distributed throughout the entire air inlet chamber. By distributing the air flow throughout the entire air inlet chamber, the gas flow is evenly distributed to the granular material in the process chamber. The air inlet chamber thus acts as a type of distribution element, distributing the gas flow evenly across the entire height of the process chamber. This allows for better control of the movement of the granular material and more efficient thermal treatment of the material.

[0018] In contrast, the prior art involved injecting the gas stream into the process chamber at multiple, individual points. This has the disadvantage that the granular material is exposed to the gas stream at multiple points, thereby negatively affecting the movement of the granular material.

[0019] The air outlet chamber has a sieve which

[0020] Separates the gas stream from the granular material. The screen is designed as a slotted screen. Slotted screens require little installation space, are low-maintenance, and are highly efficient. Such slotted screens are virtually blockage-free. The process chamber is formed by the shape of the perforated plate and the shape of the screen.

[0021] The air inlet chamber and the air outlet chamber are each connected to pipes that supply and discharge the tempered (heated or cooled) gas stream. Preferably, the discharged gas stream is fed to another process within the process plant.

[0022] A storage container for the granular material is located above the housing on the product inlet side. The storage container is filled with the granules via a conveyor line. A dosing device is preferably located near the conveyor line.

[0023] For example, the storage tank is permanently connected to the housing of the cross-flow heat exchanger, forming a single unit with the housing. However, it is also possible for the storage tank to be designed as a separate unit, detachably mounted on the housing of the cross-flow heat exchanger. This detachable connection allows the storage tank to be removed from the housing and easily cleaned.

[0024] Generally, the shape of the air inlet and / or outlet chambers is adapted to the housing shape of the cross-flow heat exchanger. The housing of the cross-flow heat exchanger is preferably angular and has, for example, a rectangular shape. The air inlet and / or outlet chambers are also angular and adapted to the housing shape of the cross-flow heat exchanger. However, it is also possible for the housing to have a cylindrical or round shape.

[0025] In a further preferred embodiment, the chamber housings of the air inlet chamber and the air outlet chamber are of identical design. This means that the same chamber housing with the same dimensions can always be mounted on the housing of the cross-flow heat exchanger, both on the air inlet side and the air outlet side. The perforated plate and the screen are detachably connected to the chamber housing, so that the perforated plate and / or the screen can be mounted either in the chamber housing of the air inlet chamber and / or the air outlet chamber. The cross-flow heat exchanger according to the invention is thus modular in design.

[0026] In a further preferred embodiment, the cross-flow heat exchanger has a process chamber with the shape of a circular ring cross-section or a hollow cylinder. The granular material is introduced into the circular ring-shaped process chamber from above and moves downwards over the entire circumference of the ring. The gas flow is introduced either from below and / or from above into the (free) center of the ring, with the gas flow flowing through the granular material from the inside to the outside. A circular perforated plate is located on the air inlet side. A slotted screen is located on the air outlet side. The perforated plate and the screen are arranged at a distance from one another and form the circular process chamber.

[0027] As a further variant, the process chamber can be shaped like a circular ring or hollow cylinder, with the gas flowing through the process chamber from the outside to the inside. A circular perforated plate is located on the air inlet side. A slotted screen is located on the air outlet side.

[0028] The slotted screen can be designed, for example, as a screen plate, curved slotted screen, drums or cylinders.

[0029] The dosing device(s) control the granular material, which moves slowly from the top (material inlet) to the bottom (material outlet) within the process chamber. The goal is to create a fixed bed within the process chamber. This should prevent an air short circuit, in which the air within the process chamber rises upwards against the direction of movement of the granular material, thereby unevenly moving the individual granules.

[0030] The dosing device is designed, for example, as a rotary valve, slide valve, dosing screw, double flap, shut-off by means of a handwheel, reel chain, electro-pneumatic shut-off or the like.

[0031] In a preferred embodiment, a dosing device is located on the material outlet side of the cross-flow heat exchanger. The dosing device controls the continuous operation of the cross-flow heat exchanger. This means that the granular material in the process chamber is always present as a fixed bed, through which the gas or air flow flows.

[0032] In a further preferred embodiment, a dosing device is located on the material inlet side and a dosing device on the material outlet side. The upper dosing device on the product inlet side can be used to control the uniform filling of the storage container. At the same time, an air short circuit can be prevented. The lower dosing device controls the fill level within the storage container. Preferably, both dosing devices (top and bottom) are connected to and controlled by a control system. The upper dosing device can be omitted if there is a sufficient bulk material bed above the process chamber.

[0033] The storage container can further comprise a fill level indicator which measures the fill level of the granular substance within the storage container and controls the upper and / or lower dosing device depending thereon.

[0034] The air inlet chamber is connected to a temperature control device via a pipe. The heat energy can be generated, for example, using a gas burner, steam generator, or hot water with a heat exchanger or electric heating coil. Waste heat from other process steps can also be utilized, for example, via a recuperator.

[0035] The tempered gas can be a heating or cooling gas. The gas can be air, for example.

[0036] A substance is generally understood to be a semolina and / or granular material. It is quite possible that the substance contains a certain amount of moisture.

[0037] The cross-flow heat exchanger according to the invention is preferably a component of a process plant. For example, the cross-flow heat exchanger can be combined with a deodorization system that removes volatile organic compounds (VOCs) from recycled plastics in a thermal process during continuous or discontinuous operation. The plastic granulate is first heated to the required process temperature and then flushed with air for a specific residence time in a silo. The air absorbs the volatile contaminants. The heated exhaust air can be reused as process heat within the process plant. This saves energy costs in particular.

[0038] The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

[0039] All information and features disclosed in the documents, including the abstract, in particular the spatial configuration shown in the drawings, are claimed as essential to the invention insofar as they are new, individually or in combination, compared to the prior art.

[0040] The invention is explained in more detail below with reference to drawings illustrating several embodiments. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0041] They show: Figure 1: Schematic representation of the cross-flow heat exchanger Figure 2: Schematic side view of the cross-flow heat exchanger Figure 3: Exploded view of the cross-flow heat exchanger Figure 4: Exploded view of the cross-flow heat exchanger in plan view Figure 5: Exploded view of the cross-flow heat exchanger with reinforcements Figure 6: Schematic representation of the cross-flow heat exchanger within a process plant Figure 7: Sectional view of another embodiment of the cross-flow heat exchanger

[0042] With the Figure 1The cross-flow heat exchanger 1 is shown. The cross-flow heat exchanger 1 consists of a housing 4, to which an air inlet chamber 7 and an air outlet chamber 8 are arranged. The process chamber 5 is located in the housing 4. The housing 4 is rectangular and has a free space 27 through which the gas 19 flows. Above the housing 4, in the area of ​​the material inlet 25, there is a storage container 2, which receives a material 18 from a conveying line 14 (see Figure 6 ). The storage container 2 is conical, causing the substance 18 to move slightly toward the process chamber 5. At the same time, the conical shape of the storage container 2 reduces the risk of a short circuit.

[0043] On the opposite side of the housing 4 is the material outlet 26, through which the material 18 is discharged from the cross-flow heat exchanger 1. The storage tank 2 serves as a reservoir for the cross-flow heat exchanger 1 and ensures that a sufficient amount of the material 18 is always present in the process chamber 5.

[0044] The housing 4 of the cross-flow heat exchanger 1 forms the basis for the two air inlet and air outlet chambers 7, 8, which are detachably arranged on the housing 4. The chamber housing 13 of the air inlet and air outlet chambers 7, 8 is identically designed. On the air inlet side 16, the air inlet chamber 7 has a nozzle 23 for connecting a pipe 6. The tempered gas 19 is introduced into the chamber housing 13 of the air inlet chamber 7 via the pipe 6. On the air outlet side 17, the air outlet chamber 8 has a nozzle 24 for connecting a pipe 22. The gas 19 is discharged from the chamber housing 13 of the air inlet chamber 8 via the pipe 22.

[0045] Figure 2shows the cross-flow heat exchanger 1 in a side view. The cross-flow heat exchanger 1 has a relatively compact and simple design. On the air inlet side 16, there is an air inlet chamber 7 with a single nozzle 23. On the air inlet side 17, there is an air inlet chamber 8, also with a single nozzle 24.

[0046] Figure 3 shows the cross-flow heat exchanger 1 with an exploded view. The cross-flow heat exchanger 1 essentially consists of a housing 4, an air inlet chamber 7, and an air outlet chamber 8. A storage tank 2 is located above the housing 4.

[0047] The air inlet chamber 7 consists of a chamber housing 13 into which a perforated plate 9 is inserted. The air outlet chamber 8 also consists of a chamber housing 13 into which a sieve 10 is inserted. The perforated plate 9 and the sieve 10 are detachably connected to the chamber housings 13.

[0048] The chamber housings 13 of the air inlet chamber 7 and the air outlet chamber 8 are preferably of identical design, whereby the construction of the cross-flow heat exchanger 1 is relatively simple and can be manufactured cost-effectively. The chamber housings 13, 13', 13" are box-shaped and can therefore accommodate a certain volume of the gas 19 or the gas stream 20. The perforated plate 9 and the sieve 10 each close off one side of the chamber housing 13, 13', 13". In the assembled state, the chamber housing 13, 13', 13" is closed, whereby the gas stream 20 can only flow out of the chamber housing 13, 13' through the openings of the perforated plate 9 and flow into the chamber housing 13, 13" through the gaps of the sieve 10.

[0049] In the assembled state, the perforated plate 9 and the sieve 10 are arranged at a distance from each other and form the process chamber 5 for the substance 18 in the space between them.

[0050] According to the Figure 3The sieve 10 is designed as a slotted sieve. The openings of the slotted sieve 10 are designed such that the substance 18 is retained and gas 19 can flow through in a gas stream 20.

[0051] Figure 4 shows a top view of the cross-flow heat exchanger 1. On the air inlet side 16 is the air inlet chamber 7 with the perforated plate 9. On the air outlet side 8 is the air outlet chamber 8 with the sieve 10. Both components 7, 8 are mounted on the housing 4 and form the process chamber 5.

[0052] With the Figure 5 the individual components of the cross-flow heat exchanger 1, as well as the gas flow 20 of the gas 19 within the cross-flow heat exchanger 1 are shown.

[0053] The gas stream 20 is introduced into the chamber housing 13' on the air inlet side 16 and encounters the perforated plate 9 there. The perforated plate 9 is designed such that the gas stream 20 backs up within the chamber housing 13', resulting in a homogeneous distribution of the gas stream 20. The gas stream 20 is thus distributed within the chamber housing 13' and discharged over the entire height of the process chamber 5. By distributing the gas stream 20 on the air inlet side 16, a uniform flow through the process chamber 5 of the cross-flow heat exchanger 1 is achieved. The movement of the substance 18 from top to bottom within the process chamber 5 is thus not disturbed by the gas stream 20. As a result, a fixed bed is always maintained.

[0054] On the opposite air outlet side 17 is the air outlet chamber 8 with the chamber housing 13" and the sieve 10. After the gas 19 flows through the process chamber 5, the gas stream 20 first encounters the sieve 10, which separates the gas 19 from the substance 18. The gas stream 20 is then combined by the chamber housing 13" and discharged through a pipe 22. The chamber housings 13, 13', 13" thus act as a distribution element or collecting element for the tempered gas 19.

[0055] According to the Figure 5 The housing 4 of the cross-flow heat exchanger 1 has numerous reinforcements 21. The reinforcements 21 serve as supports or holding devices for the perforated plate 9 or the sieve 10.

[0056] Figure 6shows the cross-flow heat exchanger 1 according to the invention within a process plant. The cross-flow heat exchanger 1 has a first metering device 3 in the area of ​​the material inlet 25, which controls the uniform filling of the feed tank 2 with the material 18 via the pipeline 14. On the opposite material outlet side 26 is a second metering device 11, which controls the movement of the fixed bed within the process chamber 5 and monitors the fill level in the feed tank 2.

[0057] The cross-flow heat exchanger 1 has a pipe 6 on the air inlet side 16, through which a tempered gas 19 is introduced into the air inlet chamber 7 with a gas flow 20. On the opposite air outlet side 17, the gas flow 20 is discharged via a pipe 22.

[0058] With the Figure 7A further embodiment of the cross-flow heat transfer medium 1 is shown. The cross-flow heat transfer medium 1 has a round housing 4. The housing 4 contains the process chamber 5. The perforated plate 9 and the sieve 10 are arranged at a distance from one another and form the process chamber 5 between them, through which the material 18 moves in the direction of arrow 12. The perforated plate 9 and the sieve 10 thus have a hollow cylindrical shape, with the material 18 moving through the space between them. A hollow cylinder or a hollow cylindrical shape is understood to mean a shape in which a smaller cylinder is cut out of a cylinder. The smaller, cut-out cylinder then forms the free space 27.

[0059] In the center of the hollow cylinder is the free space 27, which forms the air inlet side 16. The tempered gas 19 is introduced into the free space with a gas stream 20, flows through the perforated plate 9, the process chamber 5, and the sieve 10, and is discharged again from the cross-flow heat exchanger 1 on the air outlet side 17. Drawing legend

[0060] 1.Cross-flow heat exchanger 2.Feed tank 3.Dosing device (top) 4.Housing 5.Process chamber 6.Pipe of 16 7.Air inlet chamber 8.Air outlet chamber 9.Perforated plate 10.Sieve 11.Dosing device (bottom) 12.Arrow direction 13.Chamber housing of 7, 8 14.Conveyor line 15.Conveyor line 16.Air inlet side 17.Air outlet side 18.Material 20.Gas 21.Reinforcement 22.Pipe of 17 23.Connector of 16 24.Connector of 17 25.Material inlet 26.Material outlet 27.Free space

Claims

1. Cross-flow heat exchanger (1) for thermal treatment of materials (18) in the form of grit and / or granules, consisting of a housing (4) with an upper material inlet (25), a process chamber (5), through which the material (18) is moved and a lower material outlet (26), wherein starting from an air-inlet side (16), a temperature-controlled gas (19) can flow through the process chamber (5) in the direction of an air-outlet side (17), wherein the cross-flow heat exchanger (1) on the air-inlet side (16) has an air-inlet chamber (7) with a chamber housing (13, 13'), which is closed on one side by a perforated plate (9), and on the air-outlet side (17) has an air-outlet chamber (8) with a chamber housing (13, 13"), characterised in that the chamber housing (13, 13") of the air-outlet chamber (8) is closed on one side by a screen (10) and in that the screen (10) is configured as a bar screen.

2. Cross-flow heat exchanger (1) according to claim 1, characterised in that the air-inlet chamber (7) and the air-outlet chamber (8) are connected detachably to the cross-flow heat exchanger (1).

3. Cross-flow heat exchanger (1) according to claim 1 or 2, characterised in that the perforated plate (9) and / or the screen (10) are connected detachably to the chamber housing (13, 13', 13").

4. Cross-flow heat exchanger (1) according to one of claims 1 to 3, characterised in that the chamber housings (13, 13', 13") are closed by the perforated plate (9) or the screen (10), wherein the gas (19) flows out from the chamber housing (13, 13') of the air-inlet chamber (7) through openings in the perforated plate (9) and flows into the chamber housing (13, 13") of the air-outlet chamber (8) through bars of the screen (10).

5. Cross-flow heat exchanger (1) according to one of claims 1 to 4, characterised in that the bar screen is configured as a screen plate, curved bar screen, drum or cylinder.

6. Cross-flow heat exchanger (1) according to one of claims 1 to 5, characterised in that the perforated plate (9) and the screen (10) are arranged to be spaced from one another on the housing (4) and between them form the process chamber (5), through which the material (18) is moved as a fixed bed.

7. Cross-flow heat exchanger (1) according to one of claims 1 to 6, characterised in that the cross-flow heat exchanger (1) has in the region of the material inlet (25) a receiver container (2) as the storage container for the material (18).

8. Cross-flow heat exchanger (1) according to one of claims 1 to 7, characterised in that the cross-flow heat exchanger (1) has in the region of the material outlet (26) a dosing device (11).

9. Cross-flow heat exchanger (1) according to claim 8, characterised in that the dosing device (11) is configured as a rotary-vane feeder.

10. Cross-flow heat exchanger (1) according to one of claims 1 to 9, characterised in that the cross-flow heat exchanger (1) has in the region of the material inlet (25) a dosing device (3) and in the region of the material outlet (26) a dosing device (11), wherein a control controls the two dosing devices (3, 11) in such a way that the material (18) in the process chamber (5) is always present as a fixed bed.

11. Cross-flow heat exchanger (1) according to one of claims 7 to 10, characterised in that a level indicator measures the level of the material (18) in the receiver container (2), wherein a control controls at least one dosing device (3, 11) as a function of the level.

12. Cross-flow heat exchanger (1) according to one of claims 8 to 11, characterised in that the chamber housing (13, 13', 13") has a chamber volume to receive a certain quantity of the temperature-controlled gas (19).

13. Cross-flow heat exchanger (1) according to one of claims 1 to 12, characterised in that the perforated plate (9) causes homogeneous distribution of the gas (19) within the chamber housing (13, 13') of the air-inlet chamber and hence the gas (19) flows through the process chamber (5) with a uniform gas stream (20).

14. Cross-flow heat exchanger (1) according to one of claims 1 to 13, characterised in that the perforated plate (9) and the screen (10) have a rectangular or round shape.

15. Cross-flow heat exchanger (1) according to one of claims 1 to 4 and 6 to 13, characterised in that the perforated plate (9) and the screen (10) have the shape of a hollow cylinder, wherein the perforated plate (9) and the screen (10) are arranged to be spaced from one another and between them form the process chamber (5) and in that the gas stream (20) of the gas (19), starting from the centre of the hollow cylinder, flows through the perforated plate (9), the material (18), and the screen (10).