A heat exchange mechanism for drying spunlace nonwoven fabric and a hot air drying machine

Abstract

The present application relates to the technical field of spunlace nonwoven drying, and proposes a heat exchange mechanism for spunlace nonwoven drying, which comprises a water tank and a waste heat recovery tank, the water tank contains liquid heat exchange medium, the waste heat recovery tank comprises an outer tank, multiple parallel and spaced partition plates and connecting pipes, the outer diameter of the connecting pipe is smaller than the width of the partition plate, the connecting pipes on both sides of the same partition plate are located on the upper and lower sides of the partition plate, flow channels are formed in the partition plate, multiple flow channels are connected through the connecting pipes, and the flow channels are connected with the inside of the water tank. The waste heat recovery tank and the water tank can transfer the heat of the spunlace nonwoven drying tail gas to the heat exchange medium first, and then to the air in the conveying tank, which not only has the effect of energy saving and emission reduction, but also guarantees the production quality of the spunlace nonwoven.

Description

Technical Field

[0001] This invention relates to the field of spunlace nonwoven fabric drying technology, and in particular to a heat exchange mechanism and hot air dryer for drying spunlace nonwoven fabrics. Background Technology

[0002] Spunlace nonwoven fabric is a fabric obtained by using water flow to puncture and flexibly entangle fibers together. Since the fabric is in direct contact with water flow, it absorbs a large amount of water inside, so it needs to be dried during the processing of spunlace nonwoven fabric.

[0003] The drying process of spunlace nonwoven fabrics is usually carried out using hot air, such as the hot air drying device for spunlace nonwoven fabrics disclosed in the utility model with patent publication number CN215724873U. This process consumes a lot of heat energy. In order to achieve the effect of energy saving and emission reduction, the drying exhaust gas is usually recycled or directly exchanged with the air entering the dryer, such as the spunlace nonwoven fabric drying device disclosed in the utility model with patent publication number CN207991189U.

[0004] Unlike other fields, the drying exhaust gas of spunlace nonwoven fabrics contains fibrous impurities and a large amount of moisture. If it is recycled, it will not only reduce the drying quality of the spunlace nonwoven fabric, but also reduce its drying efficiency. Therefore, the method of directly recycling the exhaust gas is not conducive to the processing of spunlace nonwoven fabrics. Furthermore, the method of directly exchanging heat between the exhaust gas and hot air will also cause the exhaust gas to pollute the hot air. Summary of the Invention

[0005] In view of this, the present invention proposes a heat exchange mechanism and a hot air dryer for drying spunlace nonwoven fabrics. The heat exchange medium in the water tank is used to exchange heat between the drying exhaust gas of the spunlace nonwoven fabric and the air entering the conveying box, thereby ensuring the environmental protection effect of the spunlace nonwoven fabric processing.

[0006] The technical solution of this invention is implemented as follows: On one hand, this invention provides a heat exchange mechanism for drying spunlace nonwoven fabrics, including a water tank and a waste heat recovery tank, wherein...

[0007] The water tank contains a liquid heat exchange medium;

[0008] The waste heat recovery box includes an outer casing, multiple parallel and spaced partitions, and connecting pipes.

[0009] The outer casing is a rectangular box structure, and air inlets and air outlets are respectively opened on two opposite sides of the outer casing;

[0010] The partition is disposed inside the outer casing and abuts against the upper and lower sides of the outer casing, and multiple partitions are alternately abutted against the two sides of the outer casing where the air inlet or the air return outlet is not opened;

[0011] A connecting pipe is fixedly installed between two adjacent partitions. The outer diameter of the connecting pipe is smaller than the width of the partition. Two connecting pipes located on the upper and lower sides of the same partition are respectively located on the upper and lower sides of the partition. A flow channel is opened in the partition. Multiple flow channels are connected through the connecting pipe, and the flow channels are connected to the interior of the water tank.

[0012] Based on the above technical solutions, preferably, the flow channel includes a heat exchange chamber, an inlet, and an outlet, wherein,

[0013] The heat exchange cavity is a rectangular groove structure in longitudinal section. A guide rod is fixedly installed at each of the four apex corners of the heat exchange cavity to guide the heat exchange medium to flow through the four apex corners of the heat exchange cavity.

[0014] The inlet and outlet are located at opposite ends of the heat exchange chamber and are connected thereto. The inlet and outlet are also connected to the connecting pipe or the interior of the water tank.

[0015] More preferably, the two guide rods near the water inlet are S-shaped, and one end of the guide rod near the center line of the heat exchange cavity is used to guide the heat exchange medium to flow to the two apex corners of the heat exchange cavity near the water inlet, and the other end away from the center line of the heat exchange cavity is used to guide the heat exchange medium from the apex corner near the water inlet to the apex corner away from the water inlet.

[0016] The two guide rods near the outlet are C-shaped and are used to guide the heat exchange medium in the heat exchange chamber to the two apex corners of the heat exchange chamber near the outlet.

[0017] More preferably, the water inlet near the air inlet and the water outlet near the air return outlet are connected to the interior of the water tank.

[0018] More preferably, the partition intersects the axial direction of the air inlet but is not perpendicular to it, and the distance from the partition near the air inlet to the side of the outer casing where the air inlet is located gradually decreases from the end of the partition that abuts against the outer casing to the end that moves away from the outer casing.

[0019] Secondly, the present invention provides a hot air dryer for drying spunlace nonwoven fabrics, comprising a conveyor box for conveying the spunlace nonwoven fabric, an air inlet box, and a heat exchange mechanism as described in any one of claims, wherein...

[0020] The air inlet box is provided with an air inlet and an air outlet. The air inlet is connected to the return air inlet, and the air outlet is connected to the interior of the conveying box. It is used to supply hot air into the conveying box to dry the spunlace nonwoven fabric.

[0021] The water tank is internally connected to the conveying box and is used to convey the exhaust gas from the drying of the spunlace nonwoven fabric in the conveying box to the heat exchange medium in the water tank.

[0022] Based on the above technical solutions, preferably, a heater is fixedly installed inside the air inlet box, the air inlet and the air outlet are connected through the heater, a fan is fixedly installed on the air inlet box, and the air inlet is connected to the interior of the conveying box through the fan.

[0023] More preferably, the air outlet is provided with multiple outlets, the distance between two adjacent air outlets is greater than the outer diameter of the heater, and the distance from the side of the air inlet box where the air outlet is located to the side of the air inlet box away from the air outlet gradually decreases in the direction from the air outlet closer to the heater to the air outlet farther away from the heater.

[0024] Based on the above technical solutions, preferably, a cleaning box is fixedly installed above the water tank, the water inlet end of the flow channel is connected to the inside of the cleaning box, and the water outlet end of the flow channel and the conveying box are connected to the position inside the water tank located outside the cleaning box.

[0025] More preferably, the cleaning box has a horizontally arranged water channel, and the lower part of the water channel is toothed.

[0026] The heat exchange mechanism and hot air dryer for drying spunlace nonwoven fabrics of the present invention have the following advantages over the prior art:

[0027] (1) By setting up a waste heat recovery box and a water tank, the heat of the drying exhaust gas of spunlace nonwoven fabric can be transferred to the heat exchange medium first, and then transferred to the air entering the conveying box. This not only achieves the effect of energy saving and emission reduction, but also ensures the production quality of spunlace nonwoven fabric.

[0028] (2) By setting the waste heat recovery box to include multiple baffles and connecting the multiple baffles in an S-shape using connecting pipes with smaller outer diameters, the heat exchange area between the air and the baffles can be increased. By setting S-shaped and C-shaped guide rods in the baffles, the flow blind zone of the heat exchange medium in the flow channel can be eliminated, thereby improving the heat exchange effect between the air and the heat exchange medium.

[0029] (3) By using liquid heat exchange medium, not only can heat transfer between exhaust gas, heat exchange medium and hot air be realized, but impurities and water vapor can also be stored in the water tank to prevent them from being discharged into the environment. This not only avoids pollution to the environment, but also prevents pollution to the hot air, thus achieving a good protective effect.

[0030] (4) By setting up a cleaning box, impurities can be prevented from entering the waste heat recovery box, thus avoiding blockage of the waste heat recovery box and increasing the service life of the dryer. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a perspective view of a hot air dryer for drying spunlace nonwoven fabrics according to the present invention;

[0033] Figure 2 This is a top view of a hot air dryer for drying spunlace nonwoven fabrics according to the present invention;

[0034] Figure 3 This is a perspective view of a heat exchange mechanism for drying spunlace nonwoven fabric according to the present invention.

[0035] Figure 4 This is a cross-sectional view of a heat exchange mechanism for drying spunlace nonwoven fabric according to the present invention.

[0036] Figure 5 This is a perspective view of the partition and connecting pipe in a heat exchange mechanism for drying spunlace nonwoven fabric according to the present invention.

[0037] Figure 6 This is a cross-sectional view of the guide rod in a heat exchange mechanism for drying spunlace nonwoven fabric according to the present invention.

[0038] Figure 7 This is a perspective view of the interior of the conveyor box in a hot air dryer for drying spunlace nonwoven fabrics according to the present invention.

[0039] Figure 8 This is a perspective view of the air inlet box in a hot air dryer for drying spunlace nonwoven fabrics according to the present invention;

[0040] Figure 9 This is a perspective view of the cleaning box in a hot air dryer for drying spunlace nonwoven fabrics according to the present invention.

[0041] The components are as follows: 1. Conveying box; 2. Air inlet box; 21. Heater; 22. Fan; 201. Air inlet; 202. Air outlet; 3. Water tank; 31. Cleaning box; 301. Water trough; 4. Waste heat recovery box; 41. Outer box; 42. Partition; 421. Guide rod; 43. Connecting pipe; 401. Air inlet; 402. Air return outlet; 403. Flow channel; 4031. Heat exchange chamber; 4032. Water inlet; 4033. Water outlet. Detailed Implementation

[0042] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] like Figure 1-9 As shown, a hot air dryer for drying spunlace nonwoven fabrics according to the present invention includes a conveying box 1, an air inlet box 2, and a heat exchange mechanism.

[0044] Among them, conveyor box 1 is used to convey spunlace nonwoven fabric, such as Figure 1 and Figure 7 As shown, the conveyor box 1 is a relatively closed box structure with openings on its left and right sides for the spunlace nonwoven fabric to pass through. Inside, there are multiple rotating rollers that support and drive the spunlace nonwoven fabric.

[0045] The air inlet box 2 is used to supply hot air into the conveyor box 1 to dry the spunlace nonwoven fabric inside the conveyor box 1. The air inlet box 2 is provided with an air inlet 201 and an air outlet 202, and the air outlet 202 is connected to the interior of the conveyor box 1.

[0046] The heat exchange mechanism is used to transfer the heat in the dry exhaust gas in the conveying box 1 to the air in the air inlet box 2. The heat exchange mechanism includes a water tank 3 and a waste heat recovery box 4.

[0047] The water tank 3 contains a liquid heat exchange medium and is internally connected to the conveying box 1. It is used to transport the exhaust gas from the drying process of the spunlace nonwoven fabric in the conveying box 1 to the heat exchange medium in the water tank 3. The preferred hot heat exchange medium is water, which not only transfers heat from the exhaust gas to the heat exchange medium for heat exchange, but also retains impurities and water vapor in the exhaust gas within the heat exchange medium in the water tank 3, thus purifying the exhaust gas and preventing impurities and water vapor from being released into the environment or hot air. Regarding the connection between the water tank 3 and the conveying box 1, such as... Figure 1 As shown, this can be achieved using pipes and air pumps.

[0048] The waste heat recovery box 4 is used to transfer heat from the heat exchange medium to the air entering the air inlet box 2. The waste heat recovery box 4 includes an outer box 41, multiple parallel and spaced partitions 42, and a connecting pipe 43. The outer box 41 is a rectangular box structure. An air inlet 401 and a return air inlet 402 are respectively opened on two opposite sides of the outer box 41. The return air inlet 402 is connected to the air inlet 201. The partitions 42 are disposed inside the outer box 41 and abut against the upper and lower sides of the outer box 41. Multiple partitions 42 are alternately abutted against two sides of the outer casing 41 where no air inlet 401 or air return 402 is provided; a connecting pipe 43 is fixedly provided between two adjacent partitions 42, the outer diameter of the connecting pipe 43 is smaller than the width of the partition 42, and two connecting pipes 43 located on both sides of the same partition 42 are located on the upper and lower sides of the partition 42 respectively. Flow channels 403 are provided inside the partitions 42, and multiple flow channels 403 are connected through the connecting pipes 43, and the flow channels 403 are connected to the interior of the water tank 3; for example Figure 3 and Figure 4 As shown, by utilizing the abutment of multiple partitions 42 against the inner wall of the outer casing 41, an S-shaped passage is formed inside the outer casing 41. Outside air enters the outer casing 41 through the air inlet 401, passes through this S-shaped passage, and comes into contact with and is heated by the partitions 42 before being discharged into the air inlet box 2 through the return air inlet 402, thus achieving heat recycling and energy saving and emission reduction. Figure 4 and Figure 5 As shown, the baffle 42 and the connecting pipe 43 combine to form a continuous S-shaped structure, that is, the interior of the flow channel 403 and the connecting pipe 43 is S-shaped, allowing the heat exchange medium to flow along the S-path. Since the outer diameter of the connecting pipe 43 is smaller than the width of the baffle 42, it occupies only a small portion of the space, thereby increasing the volume of the air passage and ensuring the heat exchange efficiency of the air. Regarding the specifications of the connecting pipe 43, such as... Figure 5 As shown, taking the lower connecting pipe 43 as an example, it is preferable to make the surface area of ​​the upper, front, and rear sides of the connecting pipe 43 larger than the bottom area of ​​the space between the two partitions 42, thereby improving the heat exchange efficiency of the air while ensuring the heat exchange effect; regarding the connection between the water tank 3 and the flow channel 403, as Figure 1 and Figure 2 As shown, this can be achieved using water pumps and pipes.

[0049] like Figure 6As shown, the flow channel 403 is preferably configured to include a heat exchange cavity 4031, an inlet 4032, and an outlet 4033. The heat exchange cavity 4031 is a rectangular groove structure in longitudinal section. A guide rod 421 is fixedly installed at each of the four apex corners of the heat exchange cavity 4031 to guide the heat exchange medium to flow through the four apex corners of the heat exchange cavity 4031. The inlet 4032 and the outlet 4033 are located at both ends of the heat exchange cavity 4031 and are connected to it. The inlet 4032 and the outlet 4033 are connected to the inside of the connecting pipe 43 or the water tank 3. When the heat exchange medium flows into the heat exchange cavity 4031, it can be guided by the guide rod 421 to fill the four apex corners of the heat exchange cavity 4031 and flow at these four apex corners to ensure the heat exchange effect of the baffle 42.

[0050] As a preferred embodiment, in order to guide the flow direction of the heat exchange medium by the guide rod 421, such as Figure 6 As shown, the two guide rods 421 near the inlet 4032 can be S-shaped. The end of the guide rod near the center line of the heat exchange cavity 4031 is used to guide the heat exchange medium to flow to the two apex corners of the heat exchange cavity 4031 near the inlet 4032, and the end away from the center line of the heat exchange cavity 4031 is used to guide the heat exchange medium from the apex corner near the inlet 4032 to the apex corner away from the inlet 4032. The two guide rods 421 near the outlet 4033 can be C-shaped to guide the heat exchange medium in the heat exchange cavity 4031 to the two apex corners of the heat exchange cavity 4031 near the outlet 4033. Compared with other shapes, or using guide rods 421 of the same shape, this combination of S-shaped and C-shaped guide rods 421 has a better guiding effect.

[0051] After the heat exchange medium flows through the waste heat recovery box 4, its temperature will gradually decrease. To achieve better heat exchange effect, it is preferable to connect the water inlet 4032 near the air inlet 401 and the water outlet 4033 near the return air inlet 402 to the interior of the water tank 3. Figure 4 As shown, the temperature of the heat exchange medium in the right partition 42 is higher than that in the left partition 42, thereby improving the heat exchange efficiency.

[0052] Preferably, the partition 42 intersects the air inlet 401 axially but is not perpendicular to it, such that the distance from the partition 42 near the air inlet 401 to the side of the outer casing 41 where the air inlet 401 is located gradually decreases from the end of the partition 42 that abuts against the outer casing 41 to the end that abuts away from the outer casing 41. Figure 4As shown, the upper end of the baffle 42 is tilted towards the air inlet 401. When the air enters the outer casing 41 through the air inlet 401, it is guided by the baffle 42 and will first form a vortex in the lower right of the outer casing 41, thus avoiding the formation of a blind zone in the lower right of the outer casing 41. At the same time, since the baffle 42 is set in an inclined manner, the surface area of ​​a single baffle 42 can be increased, that is, the area of ​​a single heat exchange chamber 4031 can be increased, thereby improving its heat exchange effect.

[0053] Regarding the specific structure of the air inlet box 2, a heater 21 can be fixedly installed inside the air inlet box 2, so that the air inlet 201 and the air outlet 202 are connected through the heater 21. A fan 22 can be fixedly installed on the air inlet box 2, so that the air inlet 201 is connected to the inside of the conveying box 1 through the fan 22. When the heater 21 is started, the air can be reheated so that the air temperature meets the standard for drying air. When the fan 22 is started, the outside air can be drawn into the inside of the conveying box 1 through the waste heat recovery box 4 and the air inlet box 2 to dry the spunlace nonwoven fabric.

[0054] To improve the drying effect on spunlace nonwoven fabric, it is preferable to set multiple air outlets 202 to simultaneously dry multiple parts of the spunlace nonwoven fabric. In this case, the distance between two adjacent air outlets 202 should be greater than the outer diameter of the heater 21. The distance from the side of the air inlet box 2 where the air outlet 202 is located to the side of the air inlet box 2 away from the air outlet 202 should gradually decrease along the direction from the air outlet 202 closest to the heater 21 to the air outlet 202 furthest from the heater 21. Figure 8 As shown, setting one end of the air inlet box 2 to exhaust is flared, which not only increases the distance between the fans 22 to prevent them from interfering with each other and improves the exhaust efficiency, but also reduces the space they occupy.

[0055] Because impurities in the exhaust gas remain in the heat exchange medium inside water tank 3, they can clog the waste heat recovery box 4. To solve this problem, a cleaning box 31 can be fixedly installed above the water tank 3, connecting the inlet of the flow channel 403 to the inside of the cleaning box 31, and connecting the outlet of the flow channel 403 and the delivery box 1 to the location inside the water tank 3 located outside the cleaning box 31. To prevent impurities floating on the surface of the heat exchange medium from entering the waste heat recovery box 4, such as... Figure 9 As shown, a horizontally arranged water channel 301 can be provided on the cleaning box 31. The lower part of the water channel 301 is toothed. During operation, the liquid level of the heat exchange medium is always higher than the water channel 301 and lower than the top side of the cleaning box 31, thereby preventing impurities floating on the liquid surface of the water channel 301 from flowing into the interior of the cleaning box 31.

[0056] The working principle of the hot air dryer for drying spunlace nonwoven fabrics according to the present invention is as follows:

[0057] When the spunlace nonwoven fabric is conveyed inside the conveyor box 1, the heater 21, the fan 22, the air pump for exhausting the exhaust gas, and the water pump for circulating the heat exchange medium are started. After the heater 21 heats the air, the hot air enters the conveyor box 1 to dry the spunlace nonwoven fabric, thereby generating dry exhaust gas. This exhaust gas is pumped into the water tank 3 by the air pump to heat the heat exchange medium in the water tank 3. Then, the heat exchange medium is pumped into the waste heat recovery tank 4 by the water pump to heat the air inside the waste heat recovery tank 4, thereby reducing the burden on the heater 21 and allowing the heat generated during processing to circulate. At the same time, since the heat exchange medium is liquid, the water vapor and impurities in the exhaust gas will remain in the water tank 3 and be isolated by the cleaning box 31, achieving good cleaning and anti-clogging effects.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat exchange mechanism for drying spunlace nonwoven fabric, characterized in that: Includes a water tank (3) and a waste heat recovery tank (4), wherein, The water tank (3) contains a liquid heat exchange medium; The waste heat recovery box (4) includes an outer casing (41), multiple parallel and spaced partitions (42), and a connecting pipe (43), wherein, The outer box (41) is a rectangular box structure, and air inlet (401) and air return outlet (402) are respectively opened on two opposite sides of the outer box (41). The partition (42) is disposed inside the outer casing (41) and abuts against the upper and lower sides inside the outer casing (41), and multiple partitions (42) alternately abut against the two sides inside the outer casing (41) where the air inlet (401) or the air return outlet (402) is not opened. A connecting pipe (43) is fixedly arranged between two adjacent partitions (42). The outer diameter of the connecting pipe (43) is smaller than the width of the partition (42). The two connecting pipes (43) located on both sides of the same partition (42) are respectively located on the upper and lower sides of the partition (42). A flow channel (403) is opened in the partition (42). Multiple flow channels (403) are connected through the connecting pipe (43), and the flow channel (403) is connected to the interior of the water tank (3). The flow channel (403) includes a heat exchange chamber (4031), an inlet (4032), and an outlet (4033). The heat exchange chamber (4031) is a rectangular groove structure in longitudinal section. A guide rod (421) is fixedly installed at each of the four apex corners of the heat exchange chamber (4031) to guide the heat exchange medium through the four apex corners of the heat exchange chamber (4031). The inlet (4032) and the outlet (4033) are located at both ends of the heat exchange chamber (4031) and are connected to it. The inlet (4032) and the outlet (4033) are connected to the inside of the connecting pipe (43) or the water tank (3). The two guide rods (421) near the inlet (4032) are S-shaped, and one end of the guide rod near the center line of the heat exchange cavity (4031) is used to guide the heat exchange medium to flow to the two apex corners of the heat exchange cavity (4031) near the inlet (4032), and the other end away from the center line of the heat exchange cavity (4031) is used to guide the heat exchange medium from the apex corner near the inlet (4032) to the apex corner away from the inlet (4032); the two guide rods (421) near the outlet (4033) are C-shaped, and are used to guide the heat exchange medium in the heat exchange cavity (4031) to the two apex corners of the heat exchange cavity (4031) near the outlet (4033). The partition (42) intersects the axial direction of the air inlet (401) but is not perpendicular to it. The distance from the partition (42) near the air inlet (401) to the side of the outer casing (41) where the air inlet (401) is located gradually decreases from the end of the partition (42) that abuts against the outer casing (41) to the end that is away from the outer casing (41).

2. The heat exchange mechanism for drying spunlace nonwoven fabric as described in claim 1, characterized in that: The water inlet (4032) near the air inlet (401) and the water outlet (4033) near the return air inlet (402) are connected to the interior of the water tank (3).

3. A hot air dryer for drying spunlace nonwoven fabrics, characterized in that: Includes a conveyor box (1) for conveying spunlace nonwoven fabric, an air inlet box (2), and a heat exchange mechanism as described in claim 1 or 2, wherein, The air inlet box (2) is provided with an air inlet (201) and an air outlet (202). The air inlet (201) is connected to the return air inlet (402), and the air outlet (202) is connected to the interior of the conveying box (1) for supplying hot air into the conveying box (1) to dry the spunlace nonwoven fabric. The water tank (3) is connected to the interior of the conveying box (1) and is used to convey the exhaust gas after the spunlace nonwoven fabric is dried in the conveying box (1) to the heat exchange medium in the water tank (3).

4. A hot air dryer for drying spunlace nonwoven fabrics as described in claim 3, characterized in that: A heater (21) is fixedly installed inside the air inlet box (2). The air inlet (201) and the air outlet (202) are connected through the heater (21). A fan (22) is fixedly installed on the air inlet box (2). The air inlet (201) is connected to the interior of the conveying box (1) through the fan (22).

5. A hot air dryer for drying spunlace nonwoven fabrics as described in claim 4, characterized in that: Multiple air outlets (202) are provided. The distance between two adjacent air outlets (202) is greater than the outer diameter of the heater (21). The distance from the side of the air inlet box (2) where the air outlet (202) is located to the side of the air inlet box (2) away from the air outlet (202) gradually decreases along the direction from the air outlet (202) close to the heater (21) to the air outlet (202) away from the heater (21).

6. A hot air dryer for drying spunlace nonwoven fabrics as described in claim 3, characterized in that: A cleaning box (31) is fixedly installed above the water tank (3). The inlet end of the flow channel (403) is connected to the inside of the cleaning box (31). The outlet end of the flow channel (403) and the conveying box (1) are connected to the position inside the water tank (3) located outside the cleaning box (31).

7. A hot air dryer for drying spunlace nonwoven fabrics as described in claim 6, characterized in that: The cleaning box (31) has a horizontally arranged water channel (301), and the lower part of the water channel (301) is toothed.

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