Air cushion type pulp dryer with transverse air blow boxes

Abstract

This invention relates to an air-cushioned pulp dryer with a transverse air-blowing box. The air-blowing boxes (13) are arranged as stacked drying tables (11), with channels (15) for pulp webs (14) between the drying tables. The pulp webs (14) are arranged to run horizontally via the drying tables (11) in a zigzag pattern. A portion of the air-blowing box (13) is located above the channels (15), and the remainder of the air-blowing box (13) is located below the channels (15). Between the two channels (15), there are two types of air-blowing boxes (13) arranged together. The air-blowing box (13) is a combination box (22) having both a first top nozzle (23) and a bottom nozzle (24), and a bottom box (25) having only a second top nozzle (26), the bottom box being lower than the drying tables (11). Furthermore, the air-blowing boxes (13) are fixed.

Description

Technical Field

[0001] The present invention relates to an airborne pulpdryer having a transverse blow box, wherein the blow box is arranged as stacked drying tables with a channel for pulp web between the drying tables, the pulp web being arranged to run horizontally via the drying tables in a zigzag manner, and a portion of the blow box is located above the channel, while the remainder of the blow box is located below the channel. Background Technology

[0002] In a pulp dryer, the pulp web runs in a zigzag pattern between transverse air inlets arranged on stacked drying tables. These air inlets are referred to as nozzles. The nozzles cover the width of the pulp web and are arranged as components of an air-blowing box. In practice, several consecutive nozzles form an air-blowing exhaust. Hot drying air is blown through the nozzles, which are arranged as air-blowing boxes. The so-called top box sprays air onto the top surface of the pulp web. Correspondingly, the so-called lower box sprays air onto the underside of the pulp web. EP3733964 discloses an air-cushion type pulp dryer.

[0003] In known pulp dryers, air boxes are positioned closely side-by-side on both sides of the pulp web to maximize the dryer's drying capacity. For maintenance, the top boxes include a lifting function. In this way, each top box can be lifted, allowing the pulp web to be reached and removed after breakage. In addition to the lifting mechanism itself, extra space must be provided between the drying tables for the lifted top boxes. Furthermore, despite this extra space between the drying tables, the airflow space for exhaust is limited. In conclusion, pulp dryers have limited capacity, and the inclusion of auxiliary equipment increases costs and compromises occupational safety. Summary of the Invention

[0004] The object of this invention is to provide a novel air-cushion pulp dryer with a transverse air box, which has a simple structure, fewer air boxes, and is more efficient than before. The characteristic features of the pulp dryer according to the invention are described herein. The pulp dryer has different types of air boxes. Furthermore, more air can be supplied to the pulp dryer. In addition, there is more space for exhaust. In this way, hot air is diffused evenly and efficiently to the pulp web, and the exhaust flows with low flow resistance. This significantly enhances the drying of the pulp web. There is also more space for maintenance. In practice, there is sufficient space so that the air boxes can be fixed. In other words, broke can be removed without lifting the air boxes as in known technologies. Therefore, the absence of a lifting device simplifies the structure of the pulp dryer. At the same time, the ergonomics and safety of maintenance work are improved. Furthermore, the drying table can be lower than before, which reduces the overall height of the pulp dryer. On the other hand, more drying tables can be accommodated in current pulp dryers. Attached Figure Description

[0005] The present invention is described in detail below with reference to the accompanying drawings, which illustrate some embodiments of the invention, wherein...

[0006] Figure 1 A side view of a pulp dryer according to the present invention is shown schematically.

[0007] Figure 2 This shows a longitudinal view of a pulp dryer according to the prior art.

[0008] Figure 3 A longitudinal view of the pulp dryer according to the invention is shown.

[0009] Figure 4a A side view of a portion of the pulp dryer according to the present invention is shown.

[0010] Figure 4b It shows Figure 4a AA view,

[0011] Figure 4c It shows Figure 4a BB view,

[0012] Figure 5a It shows Figure 4b A magnified view of a portion of the image.

[0013] Figure 5b It shows Figure 4c A magnified view of a portion of the image.

[0014] Figure 5c The flow of gas supply is schematically shown.

[0015] Figure 5d The flow of exhaust gas is schematically shown.

[0016] Figure 6a One configuration of the air-blowing box according to the invention is shown.

[0017] Figure 6b Another configuration of the air-blowing box according to the invention is shown.

[0018] Figure 6c Another configuration of the air-blowing box according to the invention is shown. Detailed Implementation

[0019] Figure 1 A schematic side view of a pulp dryer according to the invention is shown. The pulp dryer has a closed hood 10 comprising stacked drying tables 11. Each drying table 11 has guide rollers 12 at both ends and an air box 13 between them. In an air-cushion pulp dryer, the pulp web 14 moves horizontally via the drying tables 11 in a zigzag pattern. Between the guide rollers 12, air blown from the air box 13 supports the pulp web. Thus, the pulp web moves over an air layer. Typically, the pulp web enters from the top of the hood 10 and exits at the bottom of the other end. The height of the drying tables depends primarily on the required air volume and the width of the pulp web. The wider the pulp web, the higher the air box and the higher the drying table. In practice, the drying table height is 250 mm to 800 mm, and a pulp dryer typically has 10 to 30 drying tables.

[0020] Here, only a portion of the air-blowing boxes is shown. In practice, the transverse air-blowing boxes arranged side-by-side fill the space between the guide rollers on both sides of the slurry web. The air-blowing boxes 13 are arranged as stacked drying tables 11, with channels 15 for the slurry web 14 between them. Figure 2 As shown, a portion of the air-blowing box 13 is located above the channel 15, while the remainder of the air-blowing box 13 is located below the channel 15. Therefore, air is blown onto both sides of the pulp fabric.

[0021] Air is delivered to the air-blowing box at one end via one or more fans. Figure 1 In this configuration, seven stacked fans 16 are arranged as a fan tower. Here, the first air chamber is open, while the next air chamber is closed. The next fan tower is then located on the other side of the shroud. In practice, air circulates through the fan towers. Furthermore, in... Figure 2 and Figure 3 Each fan tower, shown by the dashed rectangle, contains a heating and filtration unit 17. In this way, the air is continuously heated and filtered.

[0022] Figure 2A longitudinal view of a pulp dryer according to the prior art is shown. Here, fan 16 is on the left, blowing hot air into supply chamber 18, which in turn blows it into air-blowing boxes 13. Since the opposite ends of the air-blowing boxes are closed, the blown air is discharged to the pulp web 14 via nozzles. Small arrows indicate the air ejected from the nozzles. The exhaust then flows between the air-blowing boxes 13 to exhaust chamber 19, which in turn flows to the adjacent fan tower. The upper two air-blowing boxes 13 are shown in the production position. The next two air-blowing boxes are in a maintenance position, in which the so-called top box is raised. Thus, the passage widens, for example, enabling the removal of waste paper. A lifting device 20 is provided for raising the air-blowing boxes 13.

[0023] Figure 3 A portion of a pulp dryer according to the invention is disclosed. Here, only the upper portion of the hood 10 is shown. A top plate 21 is provided between the supply chamber 18 and the exhaust chamber 19, which restricts airflow out of the hood 10. By adjusting the amount and flow of the supply and exhaust air, the drying capacity of the pulp dryer is kept optimal, and energy loss is minimized.

[0024] According to the invention, between the two channels 15, there are two types of air-blowing boxes 13 arranged together. First, there is a combination box 22, which has both a first top nozzle 23 and a bottom nozzle 24. Figure 5c Next, a bottom chamber 25 is provided, which has only a second top nozzle 26 and is lower than the drying table 11. Here, the bottom chamber is below the pulp web, and the second top nozzle sprays air to form the underside of the pulp web, while the second top nozzle is on the top surface of the bottom chamber. Therefore, the known top chamber is absent here. Finally, the air blowing box 13 is fixed. Many advantages are achieved through this combination. The combined chamber is spacious, thus allowing a large amount of air to be delivered into the pulp dryer. Furthermore, through the combined chamber, air is simultaneously directed upwards and downwards towards the pulp web. However, due to the presence of only a low, single bottom chamber, there is a clear exhaust passage. In practice, the exhaust flow is even accelerated within the funnel thus formed. This facilitates air circulation, thereby benefiting the efficiency of the pulp dryer. Figure 4c , Figure 5b and Figure 5d The airflow is indicated by arrows. The new configuration achieves most of the double-sided drying efficiency, with sufficient space between the air boxes for exhaust and ample access to the pulp web for cleaning. Furthermore, the extra space facilitates maintenance. Finally, the air boxes can be fixed, thus eliminating the need for existing lifting devices. Simultaneously, the air boxes on different drying tables can be closer together than before. In this way, the drying tables become lower, allowing for smaller guide rollers. Therefore, the overall structure of the pulp dryer becomes more compact.

[0025] For example, such as Figure 5c As shown, the combination box 22 is a single box with a first top nozzle 23 and a bottom nozzle 24. This type of box has a simple structure and is easy to manufacture. Alternatively, the combination box 22 can be a combination of two boxes fixed on top of each other. Figures 6a to 6c In this way, even known air-blowing boxes can be used and combined into a composite box. At the same time, the stiffness of the composite box is increased, which reduces bending and vibration.

[0026] Since the air-blowing box is fixed, the combined box, in particular, can be taller than before. In practice, the maximum height h of the combined box 22 is 60% to 90% of the height H of the drying table 11, advantageously 70% to 95%. Simultaneously, the maximum amount of air can be supplied to the combined box. Since the bottom box is single, its height can vary. If more air is required, the bottom box can be taller than before. However, in practice, the maximum height k of the bottom box 25 is 20% to 70% of the height H of the drying table 11, advantageously 40% to 60%. In this way, more space is provided than known liftable air-blowing boxes. Additionally, the exhaust flow is freer, which is enhanced by the suction of the adjacent fan tower.

[0027] Even greater space is achieved when the bottom chamber 25 is arranged to taper (gradually narrowing) in its longitudinal direction. For example, the open end is approximately half the height of the drying table, while the closed end is approximately one-quarter of that height. This facilitates maintenance and enables sensing and visual monitoring. In other words, the movement of the pulp web can be seen from the side of the pulp dryer. Furthermore, sensors can be installed if needed.

[0028] As a basic rule, the combination box 22 and the bottom box 25 are arranged alternately, such as Figure 6a As shown. In other words, every other one is a combo box. However, this rule can be varied. For example, in... Figure 6b In this configuration, two combination boxes 22 may be present after a bottom box 25. Alternatively, two combination boxes 22 may be present after two bottom boxes 25 arranged side by side. Figure 6c These two variations increase the air volume while still allowing air to reach between the air chambers without lifting. In the illustrated embodiment, each fan has six air chambers. Furthermore, the six air chambers are supported together at the open ends.

[0029] As mentioned earlier, each blowbox 13 has an open feed head 27 and an opposing closed end 28. Instead of a lifting device, the closed end 28 has a top support 29. The top support 29 is simple and does not restrict the flow of exhaust gas. Here, the top support 29 is arranged on a square tube 30 in the longitudinal direction of the machine. This arrangement accommodates thermal expansion without twisting or deforming the blowbox. Furthermore, the closed end 28 can be lifted out from the top support 29. This allows for both assembly and maintenance. In addition, the blowbox can be moved away or partially removed during web breakage.

[0030] The nozzle is an orifice or slit, serving as its simplest form for air blowing. Advantageously, a portion of the top nozzles 23, 26 has a coanda shaping section 31 for air blowing. Figure 5d This facilitates airflow along the slurry web and allows for smoother movement of the slurry web. Furthermore, a portion of the assembly box 22 has a flat bottom surface 32. These boxes are easily manufactured, for example, by bending thin metal sheets.

[0031] As an example, the following features an air-cushion dryer with a web width of 5-6 meters. When the air-blowing boxes are fixed, it has the capacity to produce 1400 tons of air-dried pulp per day, eliminating each second top air-blowing box. This means a total reduction of approximately 40% in the number of air-blowing boxes. The external dimensions of the pulp dryer remain the same. However, because the drying table height can be scaled down proportionally, the diameter of the guide rollers decreases from 475mm to 415mm. Simultaneously, the number of drying tables increases from 25 to 29, increasing the drying length by 16%. This is compensated for by the reduced number of air-blowing boxes. Furthermore, with the reduced number of air-blowing boxes, new air-blowing box configurations can be made from existing ones. At the same time, air-blowing box lifting equipment becomes unnecessary. The pulp dryer will be simpler and more compact, yet easier to operate and maintain. As a result, construction and operating costs are reduced by as much as 6% to 12%.

[0032] The air-cushion pulp dryer is characterized by non-contact drying, with the pulp web running along the entire drying length via a high-drying-capacity air-blowing box design. The pulp web runs directly within the dryer, eliminating any risk of breakage. High overall efficiency with low-pressure-loss circulating airflow, combined with an all-steel steam swirl tube, improves drying process performance. Excellent operability and enhanced drying are achieved through the new air-blowing box. Furthermore, the dryer's high energy efficiency results in energy savings. Additionally, the airflow circulation features low pressure loss. In summary, stable pulp web operation is achieved with reduced production and maintenance costs and downtime.

Claims

1. An air cushion type pulp dryer having a transverse air blowing box, wherein, The air-blowing box (13) is arranged as a stacked drying table (11) with a channel (15) between the drying tables for the slurry web (14), the slurry web being arranged to run horizontally in a zigzag manner via the drying table (11), and a portion of the air-blowing box (13) being above the channel (15) and the remainder of the air-blowing box (13) being below the channel (15), characterized in that, between the two channels (15), there are two types of air-blowing boxes (13) arranged together, namely, a combination box (22) having both a first top nozzle (23) and a bottom nozzle (24), and a bottom box (25) having only a second top nozzle (26), and the bottom box being lower than the drying table (11), and the air-blowing box (13) being fixed.

2. The pulp dryer according to claim 1, characterized in that The combination box (22) is a single box having the first top nozzle (23) and the bottom nozzle (24).

3. The pulp dryer according to claim 1, characterized in that The combination box (22) is a combination of two boxes that are stacked and fixed together.

4. The pulp dryer according to any one of claims 1 to 3, characterized in that The maximum height (h) of the combination box (22) is 60% to 90% of the height (H) of the drying table (11), advantageously, it is 70% to 95% of the height (H) of the drying table (11).

5. The pulp dryer according to any one of claims 1 to 3, characterized in that, The maximum height (k) of the bottom box (25) is 20% to 70% of the height (H) of the drying table (11), advantageously, it is 40% to 60% of the height (H) of the drying table (11).

6. The pulp dryer according to claim 5, characterized in that The bottom box (25) is arranged to taper in the longitudinal direction of the bottom box (25).

7. The pulp dryer according to any one of claims 1 to 3, 6, characterized in that The combination box (22) and the bottom box (25) are arranged alternately.

8. The pulp dryer according to any one of claims 1 to 3, 6, characterized in that Following a bottom box (25), there are two combination boxes (22).

9. The pulp dryer according to any one of claims 1 to 3 and 6, characterized in that, Two combination boxes (22) are arranged side by side, followed by two bottom boxes (25).

10. The pulp dryer according to any one of claims 1 to 3, 6, characterized in that Each air-blowing box (13) has an open feed head (27) and an opposite closed end (28), the closed end having a top support (29).

11. The pulp dryer according to claim 10, characterized in that The closed end (28) can be raised from the top support (29).

12. The pulp dryer according to any one of claims 1 to 3, 6, 11, characterized in that, A portion of the first top nozzle (23) and the second top nozzle (26) has a canda shape (31) for air blowing.

13. The pulp dryer according to any one of claims 1 to 3, 6, 11, characterized in that, A portion of the combination box (22) has a flat bottom surface (32).

14. The pulp dryer according to any one of claims 1 to 3, 6, and 11, characterized in that, The height (H) of the drying table (11) is 250 mm to 800 mm.

15. The pulp dryer according to any one of claims 1 to 3, 6, 11, characterized in that The pulp dryer includes stacked fans (16) with heating and filtration devices (17).

Images