A concrete steam curing apparatus and method

Abstract

The present application relates to concrete steam curing technical field, specifically, it is a kind of concrete steam curing device, it includes curing box and evaporation device, curing box is provided with the injection assembly being communicated with evaporation device, curing box two sides are provided with a plurality of first flow guide plate for accelerating gas circulation and opposite direction, injection assembly is driven to rotate by steam of itself, and steam is injected to curing box and first flow guide plate, injection assembly includes support and rotatingly arranged on support and the delivery pipe being communicated with evaporation device, a plurality of fan blades are peripherally arranged on delivery pipe, the nozzle of different angles is arranged on the side of curing box to fan blade, fan blade is driven to rotate by nozzle, and steam sprayed by nozzle is blown to curing box by fan blade;By setting the cooperation of injection assembly and evaporation device, fan blade can autorotate and drive the whole delivery pipe to rotate, and steam is evenly blown to each corner in curing box.

Description

Technical Field

[0001] This invention relates to the field of concrete steam curing technology, and more specifically, to a concrete steam curing device and method. Background Technology

[0002] In the production of concrete products (such as precast components, pipe piles, and railway sleepers), curing is a crucial process that determines their mechanical properties and durability. Traditional natural curing has a long cycle (usually 7-28 days), which is difficult to meet the efficiency requirements of industrial production. Steam curing technology accelerates the cement hydration reaction by controlling temperature and humidity, which can shorten the curing cycle to 12-24 hours, significantly improving production efficiency.

[0003] Existing steam curing devices often involve directly injecting steam into a sealed space, allowing it to spread and contact the concrete. While steam curing aims to improve efficiency and shorten curing time, this method of steam spreading can lead to problems. As steam spreads from the nozzle, density differences and airflow disturbances can cause "vortices" or "dead zones" to form within the sealed space. This results in steam accumulation at the top and insufficient steam at the bottom. Furthermore, steam spreading requires maintaining a high steam flow rate for an extended period to fill the space, leading to low actual utilization. Consequently, the hardening speed of different areas of the concrete becomes inconsistent, and the hydration reaction between the surface and interior is uneven. This can cause color differences or, in severe cases, stress cracks.

[0004] Based on this, the present invention discloses a concrete steam curing device and method. Summary of the Invention

[0005] To address the problem that steam curing devices proposed in the background art, which rely on steam propagation for curing, are prone to forming "vortices" or "dead zones" in enclosed spaces, resulting in uneven steam distribution, with steam accumulating at the top and insufficient at the bottom, not only has low utilization efficiency but also causes uneven hardening speed and hydration reaction in different areas of concrete, potentially leading to color differences or even stress cracks, this invention provides a concrete steam curing device, which includes a curing box and an evaporation device. The curing box has an inlet at the front end and a collection box for collecting condensate at the bottom.

[0006] Because existing curing methods involve injecting steam into the curing chamber and then spreading it to various locations within the chamber and into contact with the concrete products, the steam tends to form "vortices" or "dead zones" in the enclosed space due to density differences and airflow disturbances during its spread. This results in steam accumulation at the top and insufficient steam at the bottom. Furthermore, the spread of steam requires maintaining a high steam flow rate for an extended period to fill the space, but the actual effective utilization rate is low.

[0007] In this scheme, the curing box is equipped with a spraying component connected to the evaporation device. The spraying component is driven by its own steam to rotate and spray steam into the curing box.

[0008] As a further improvement to this technical solution, the spraying assembly includes a support and a conveying pipe rotatably mounted on the support and connected to the evaporation device. Several fan blades are circumferentially arranged on the conveying pipe. Each fan blade has a nozzle at a different angle on its side facing the curing chamber. The fan blades are driven to rotate by the nozzles, and the fan blades blow the steam ejected from the nozzles into the curing chamber. The nozzles on the fan blades include a first nozzle, a second nozzle, and a third nozzle. The first nozzle sprays steam parallel to the horizontal plane into the curing chamber. The second nozzle is positioned at a 45° angle relative to the first nozzle into the curing chamber, and the third nozzle is positioned at a 90° angle relative to the first nozzle. A connecting pipe is provided inside the fan blades, and the first, second, and third nozzles are interconnected through the connecting pipe, which is also connected to the conveying pipe. It should be noted that the first, second, and third nozzles are arranged radially from the inside to the outside along the conveying pipe. The air pressure generated by the second and third nozzles driving the fan blades to rotate is a positive pressure relative to the curing chamber.

[0009] Based on this, although the steam ejected by the nozzle system is accelerated by the rotating fan blades and blown into the curing box, improving the circulation efficiency, in order to ensure that both sides of the concrete product are also sprayed with high-speed steam, and at the same time to further agitate the steam flow in the entire curing box, so that the steam in the curing box is not in a static and diffuse state, but in a state of rapid circulation and agitation, this can further reduce steam dead zones and temperature differences, and at the same time increase the steam flow rate on the concrete product.

[0010] As a further improvement to this technical solution, several first guide plates with opposite directions for accelerating gas circulation are respectively provided on both sides of the curing box. The first guide plates have a streamlined structure, and the lower end of the first guide plate located at the bottom of the curing box is in contact with the inner wall of the bottom of the curing box. The higher end of the first guide plate located at the top of the curing box has a gap with the top of the curing box, and the side of the first guide plate away from the inner wall of the curing box extends into the wind force zone of the fan blade.

[0011] In another embodiment, a hybrid component for controlling the direction of airflow from the fan blades is installed in front of the delivery pipe inside the curing box.

[0012] As a further improvement to this technical solution, the hybrid component includes a drive bevel gear and a rotating rod. The drive bevel gear is fixedly connected to the conveying pipe, and the rotating rod is rotatably connected to the bottom of the curing box. A first bevel gear and a second bevel gear are symmetrically arranged on the rotating rod. The upper and lower ends of the drive bevel gear mesh with the second bevel gear and the first bevel gear, respectively. A second guide plate is provided on the rotating rod above the second bevel gear and below the first bevel gear. It is worth mentioning that the second guide plate has a conical structure, and the toothed part of the upper part of the drive bevel gear is smooth. The drive bevel gear drives the second guide plate to swing horizontally 180° back and forth through the first bevel gear and the second bevel gear.

[0013] The second objective of this invention is to provide a method for using a concrete steam curing device, characterized in that:

[0014] Includes the following steps:

[0015] S1. Place the concrete product in the middle of the curing box through the inlet, and then start the evaporation device after sealing the inlet.

[0016] S2. After being pressurized by the evaporation device, the steam is ejected at high speed through the nozzle. The high-speed steam ejected by the third nozzle and the second nozzle drives the fan blades to rotate. After the fan blades rotate, the steam ejected by the first nozzle, the second nozzle and the third nozzle blows into the curing box.

[0017] S3. The rotation of the fan blades drives the conveying pipe to rotate. The conveying pipe drives the second guide plate to swing horizontally 180° back and forth through the drive bevel gear, the first bevel gear and the second bevel gear, which swings the steam blown by the fan blades into the curing box.

[0018] S4. The steam blown into the curing chamber is accelerated by several first guide plates on one side, hits the inner wall of the front end of the curing chamber, and then returns through several first guide plates on the other side to accelerate the steam flow and circulation inside the curing chamber.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. In this concrete steam curing device, by setting up a spraying assembly in conjunction with an evaporation device, the spraying assembly of this invention includes a support, a conveying pipe rotatably mounted on the support, and several fan blades arranged circumferentially on the conveying pipe. When high-temperature, high-pressure steam is input into the connecting pipe through the conveying pipe and sprayed out through the first, second, and third nozzles, due to the different angles of the nozzles, especially the reverse propulsion force provided by the third and second nozzles, the fan blades can rotate and drive the entire conveying pipe to rotate, evenly blowing the steam to all corners of the curing chamber. This not only solves the "vortex" or "dead zone" problems caused by traditional steam propagation methods, but also improves the effective utilization rate of steam, ensuring that all parts of the concrete product can receive steam curing evenly, thereby achieving consistent hardening speed and balanced hydration reaction.

[0021] 2. In this concrete steam curing device, a hybrid component is used to control the steam flow direction. The hybrid component includes a drive bevel gear, a rotating rod, and a first bevel gear and a second bevel gear on it. As the delivery pipe rotates, the drive bevel gear drives the second guide plate to reciprocate horizontally, guiding the high-temperature, high-pressure steam blown out by the fan blades in an oscillating manner toward the concrete product. The gas circulation is further accelerated by the first guide plates on both sides. This design not only increases the steam flow on both sides of the concrete product but also promotes rapid steam circulation throughout the curing chamber, reduces temperature differences and density stratification, and improves the steam coverage and curing efficiency.

[0022] 3. In this concrete steam curing device, the streamlined structure of the first guide plate, located on both sides of the curing chamber, helps to accelerate gas circulation and optimize the steam flow path. The lower end of the bottom first guide plate is in contact with the inner wall of the bottom of the curing chamber, while the higher end of the top first guide plate has a gap with the top. This layout can effectively prevent steam from accumulating in one place, ensuring uniform distribution of steam throughout the curing chamber and reducing steam dead zones and temperature differences. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a top view of the cross-sectional structure of the curing box of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the first guide plate of the present invention;

[0026] Figure 4 This is one of the structural schematic diagrams of the hybrid component of the present invention;

[0027] Figure 5 This is a second schematic diagram of the structure of the hybrid component of the present invention;

[0028] Figure 6 This is a schematic diagram of the spray assembly of the present invention;

[0029] Figure 7 This is a schematic diagram of the fan blade structure of the present invention;

[0030] Figure 8 This is a schematic diagram of the nozzle structure of the present invention.

[0031] The meanings of the labels in the diagram are as follows:

[0032] 1. Curing box; 2. Inlet; 3. Collection box; 4. Evaporation device; 5. Spray assembly; 6. Hybrid assembly; 7. First guide vane;

[0033] 51. Support; 52. Delivery pipe; 53. Fan blade; 54. First nozzle; 55. Second nozzle; 56. Third nozzle; 57. Connecting pipe;

[0034] 61. Drive bevel gear; 62. Rotating rod; 63. First bevel gear; 64. Second bevel gear; 65. Second guide plate. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Existing steam curing devices, which cure through steam propagation, are prone to creating "vortices" or "dead zones" in enclosed spaces, resulting in uneven steam distribution, with steam accumulating at the top and insufficient at the bottom. This not only leads to low utilization efficiency but also causes uneven hardening speed and hydration reaction in different areas of the concrete, potentially causing color differences or even stress cracks.

[0037] Therefore, the present invention provides a concrete steam curing device, see [link to relevant documentation]. Figures 1-2 As shown, it includes a curing box 1 and an evaporation device 4. The curing box 1 has an inlet 2 at the front end and a collection box 3 for collecting condensate at the bottom.

[0038] During operation, concrete products are placed into curing chamber 1 through inlet 2, and then inlet 2 is sealed. Steam enters curing chamber 1 to cure the concrete products, while the condensed liquid water is collected in collection chamber 3.

[0039] Because existing curing methods involve injecting steam into curing chamber 1 and then spreading it to various locations within the chamber, coming into contact with the concrete products, the steam, after exiting the nozzle, tends to form "vortices" or "dead zones" within the enclosed space due to density differences and airflow disturbances during its spread. This results in steam accumulation at the top and insufficient steam at the bottom. Furthermore, steam spread requires maintaining a high steam flow rate for an extended period to fill the space, but the actual effective utilization rate is low. Therefore, in this solution, referring to... Figure 2 and Figure 4 As shown, the curing chamber 1 is equipped with a spray assembly 5 that is connected to the evaporation device 4. The spray assembly 5 is driven by its own steam to rotate and spray steam into the curing chamber 1.

[0040] The spray assembly 5 includes a bracket 51 and a conveying pipe 52 rotatably mounted on the bracket 51 and connected to the evaporation device 4. Several fan blades 53 are arranged circumferentially on the conveying pipe 52. The fan blades 53 are provided with nozzles at different angles on the side of the fan blades 53 facing the curing box 1. The fan blades 53 are driven to rotate by the nozzles, and the fan blades 53 blow the steam sprayed from the nozzles into the curing box 1.

[0041] Specifically, such as Figures 6-8 As shown, the nozzles on the fan blade 53 include a first nozzle 54, a second nozzle 55, and a third nozzle 56. The first nozzle 54 sprays parallel to the horizontal plane into the curing chamber 1. The second nozzle 55 is set at a 45° angle relative to the first nozzle 54 into the curing chamber 1. The third nozzle 56 is set at a 90° angle relative to the first nozzle 54. A connecting pipe 57 is provided inside the fan blade 53. The first nozzle 54, the second nozzle 55, and the third nozzle 56 are interconnected through the connecting pipe 57, and the connecting pipe 57 is connected to the conveying pipe 52. It should be noted that the first nozzle 54, the second nozzle 55, and the third nozzle 56 are arranged radially from the inside to the outside along the conveying pipe 52. The wind pressure generated by the second nozzle 55 and the third nozzle 56 driving the fan blade 53 to rotate is a positive pressure relative to the curing chamber 1.

[0042] During operation, high-temperature, high-pressure steam is introduced into the connecting pipe 57 via the evaporation device 4 through the delivery pipe 52, and then ejected through the first nozzle 54, the second nozzle 55, and the third nozzle 56. Figure 8It can be seen that the high-pressure steam ejected from the third nozzle 56 is perpendicular to the fan blade 53, which generates a reverse thrust, causing the fan blade 53 to rotate. The high-pressure steam ejected from the second nozzle 55, at a 45° angle relative to the first nozzle 54, is decomposed into a jet force parallel to the first nozzle 54 and a jet force perpendicular to the fan blade 53. The force perpendicular to the first nozzle 54 from the second nozzle 55, together with the third nozzle 56, forms a reverse thrust, further accelerating the rotation of the fan blade 53. The jet force parallel to the first nozzle 54 from the second nozzle 55, together with the first nozzle 54, sprays the high-temperature, high-pressure steam into the curing box 1. The steam ejected from the entire nozzle system, under the wind force generated by the rotation of the fan blade 53, is accelerated into the curing box 1, causing the steam in the curing box 1 to spread rapidly, improving the steam circulation efficiency in the curing box 1, and ensuring that the steam reaches all corners of the curing box 1 as quickly as possible, reducing steam dead zones. In other words, steam is delivered to the first nozzle 54, the second nozzle 55, and the third nozzle 56 on the fan blade 53 through the delivery pipe 52, breaking through the traditional natural steam diffusion mode. Through active injection and forced convection, the steam coverage rate is increased from 60% to 95%, the steam circulation efficiency is increased by 50%, the maintenance time is shortened, and the needs of industrial production are met.

[0043] Furthermore, refer to Figures 2-5 As shown, although the steam ejected by the nozzle system is accelerated by the rotating fan blades 53 and blown into the curing chamber 1, improving the circulation efficiency, in order to ensure that both sides of the concrete product are also sprayed with high-speed steam, and at the same time to further agitate the steam flow in the entire curing chamber 1, so that the steam in the curing chamber 1 is not in a static and diffused state, but in a state of rapid circulation and agitation, this can further reduce steam dead zones and temperature differences, and at the same time increase the steam flow rate on the concrete product, the present invention adopts several first guide plates 7 on both sides of the curing chamber 1 to accelerate gas circulation in opposite directions, and a hybrid component 6 is set in front of the conveying pipe 52 in the curing chamber 1 to control the direction of the fan blades 53. This allows the high-temperature and high-pressure steam blown by the fan blades 53 to be blown towards the concrete product in an oscillating manner, and at the same time, the several first guide plates 7 on both sides of the concrete product increase the steam flow rate on both sides of the concrete product, further improving the steam circulation.

[0044] The first guide plate 7 has a streamlined structure. The lower end of the first guide plate 7 located at the bottom of the maintenance box 1 is attached to the inner wall of the bottom of the maintenance box 1. The higher end of the first guide plate 7 located at the top of the maintenance box 1 has a gap with the top of the maintenance box 1. The side of the first guide plate 7 away from the inner wall of the maintenance box 1 extends into the wind zone of the fan blade 53.

[0045] The hybrid component 6 includes a drive bevel gear 61 and a rotating rod 62. The drive bevel gear 61 is fixedly connected to the conveying pipe 52, and the rotating rod 62 is rotatably connected to the bottom of the curing box 1. A first bevel gear 63 and a second bevel gear 64 are symmetrically arranged on the rotating rod 62. The upper and lower ends of the drive bevel gear 61 mesh with the second bevel gear 64 and the first bevel gear 63, respectively. A second guide plate 65 is provided on the rotating rod 62 above the second bevel gear 64 and below the first bevel gear 63. It is worth mentioning that the second guide plate 65 has a conical structure, and the toothed part of the upper part of the drive bevel gear 61 is smooth. The drive bevel gear 61 drives the second guide plate 65 to swing horizontally 180° back and forth through the first bevel gear 63 and the second bevel gear 64.

[0046] During operation, the conveying pipe 52 rotates, driving the drive bevel gear 61 to rotate. When the drive bevel gear 61 rotates, and the teeth on the drive bevel gear 61 mesh with the second bevel gear 64, it drives the second guide plate 65 to rotate counterclockwise. At this time, the first bevel gear 63 is located on the smooth part of the drive bevel gear 61. The drive bevel gear 61 continues to rotate until the toothed part of the drive bevel gear 61 disengages from the second bevel gear 64. Then, the toothed part of the drive bevel gear 61 meshes with the first bevel gear 63. After that, the drive bevel gear 61 drives the second guide plate 65 to rotate clockwise through the first bevel gear 63. This process repeats, forming a horizontal 180° reciprocating swing of the second guide plate 65. During the swinging of the second guide plate 65, the steam blown out by the fan blade 53 is guided to both sides of the curing box 1, accelerating the steam flow on both sides of the concrete product. During the guidance process, when the steam is guided to one side, the steam passes through several streamlined first guide plates 7, which will accelerate the steam flow on the side of the concrete product. When the steam flows through the first guide plate 7 to the end of the curing box 1 away from the fan blade 53, it will circulate back in reverse through the first guide plate 7 on the other side. This further improves the circulation and flow rate of steam in the curing box 1, and reduces steam dead zones and density and temperature stratification.

[0047] In other words, the drive bevel gear 61 rotates with the conveying pipe 52, and drives the second guide plate 65 to oscillate 180° periodically through the first bevel gear 63 and the second bevel gear 64, changing the direction of the mainstream steam flow; the first guide plate 7 guides the airflow to circulate along both sides of the concrete, forming a closed-loop convection; the dynamic airflow disturbance breaks the static steam stratification and avoids excessive accumulation of condensate; the guide plate forces the airflow to adhere to the concrete surface, improving the steam contact efficiency and reducing hardening color difference.

[0048] In summary, this invention achieves active steam injection and forced convection through fan blades 53 and multi-angle nozzles. Combined with bevel gear drive and guide plate to dynamically control the airflow direction, and supplemented by a condensate recovery system to improve resource utilization, it forms an integrated solution of injection-circulation-recovery. This effectively solves the problem that existing steam curing devices, which rely on steam propagation for curing, are prone to forming "vortices" or "dead zones" in enclosed spaces, resulting in uneven steam distribution, with steam accumulating at the top and insufficient at the bottom. This not only leads to low utilization but also causes uneven hardening speed and hydration reaction in different areas of concrete, potentially causing color differences or even stress cracks.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concrete steam curing device, comprising a curing chamber (1) and an evaporation device (4), wherein the curing chamber (1) has an inlet (2) at its front end and a collection box (3) for collecting condensate is provided at the bottom of the curing chamber (1), characterized in that: The curing box (1) is provided with a spray assembly (5) connected to the evaporation device (4) near the inner side of the evaporation device. Several first guide plates (7) with opposite directions are provided on both sides of the curing box (1) to accelerate gas circulation. The spray assembly (5) sprays steam into the curing box (1) and onto the first guide plates (7) after being driven to rotate by its own steam. The spray assembly (5) includes a bracket (51) and a conveying pipe (52) rotatably mounted on the bracket (51) and connected to the evaporation device (4). The conveying pipe (52) has several fan blades (53) arranged circumferentially. Each fan blade (53) has a nozzle with a different angle on the side facing the curing box (1). The fan blades (53) are driven to rotate by the nozzles, and the fan blades (53) blow the steam sprayed from the nozzles into the curing box (1). The nozzles on the fan blades (53) include a first nozzle (54), a second nozzle (55), and a third nozzle (56). The first nozzle (54) sprays into the curing box (1) parallel to the horizontal plane, the second nozzle (55) is set at a 45° angle relative to the first nozzle (54) towards the curing box (1), and the third nozzle (56) is set at a 90° angle relative to the first nozzle (54). The fan blade (53) is provided with a connecting pipe (57), the first nozzle (54), the second nozzle (55) and the third nozzle (56) are connected to each other through the connecting pipe (57), and the connecting pipe (57) is connected to the conveying pipe (52). The first guide plate (7) has a streamlined structure. The lower end of the first guide plate (7) located at the bottom of the curing box (1) is in contact with the inner wall of the bottom of the curing box (1). The higher end of the first guide plate (7) located at the top of the curing box (1) has a gap with the top of the curing box (1). When working, the steam blown into the curing box (1) is accelerated by several first guide plates (7) on one side, hits the inner wall of the front end of the curing box (1), and then returns through several first guide plates (7) on the other side to accelerate the steam flow circulation in the curing box (1). Inside the curing box (1), in front of the conveying pipe (52), is a hybrid assembly (6) for controlling the airflow direction of the fan blades (53). The hybrid assembly (6) includes a drive bevel gear (61) and a rotating rod (62). The drive bevel gear (61) is fixedly connected to the conveying pipe (52), and the rotating rod (62) is rotatably connected to the bottom of the curing box (1). A first bevel gear (63) and a second bevel gear (64) are symmetrically arranged on the rotating rod (62). The upper and lower ends of the drive bevel gear (61) are respectively connected to the second bevel gear (64) and the first bevel gear. (63) meshing, the rotating rod (62) is provided with a second guide plate (65) above the second bevel gear (64) and below the first bevel gear (63); the second guide plate (65) has a conical structure; the upper part of the driving bevel gear (61) with teeth is smooth, and the driving bevel gear (61) drives the second guide plate (65) to swing horizontally 180° back and forth through the first bevel gear (63) and the second bevel gear (64); the side of the first guide plate (7) away from the inner wall of the maintenance box (1) extends into the wind zone of the fan blade (53).

2. The concrete steam curing device according to claim 1, characterized in that: The first nozzle (54), the second nozzle (55) and the third nozzle (56) are arranged in sequence from the inside to the outside along the radial direction of the delivery pipe (52).

3. The concrete steam curing device according to claim 2, characterized in that: The wind pressure generated by the second nozzle (55) and the third nozzle (56) driving the fan blades (53) to rotate is positive pressure compared to the curing box (1).

4. The method of using the concrete steam curing device according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Place the concrete product in the middle of the curing box (1) through the inlet (2), close the inlet (2), and then start the evaporation device (4); S2. After being pressurized by the evaporation device (4), the steam is ejected at high speed through the nozzle. The high-speed steam ejected through the third nozzle (56) and the second nozzle (55) drives the fan blade (53) to rotate. After the fan blade (53) rotates, it blows the steam ejected by the first nozzle (54), the second nozzle (55) and the third nozzle (56) into the curing box (1). S3. The fan blade (53) rotates, driving the conveying pipe (52) to rotate. The conveying pipe (52) drives the second guide plate (65) to swing horizontally 180° back and forth through the drive bevel gear (61), the first bevel gear (63) and the second bevel gear (64), which swings the steam blown by the fan blade (53) into the curing box (1). S4. The steam blown into the curing box (1) is accelerated by several first guide plates (7) on one side, hits the inner wall of the front end of the curing box (1), and then returns through several first guide plates (7) on the other side to accelerate the steam flow circulation in the curing box (1).

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