Drying method of polyester fabric-based canvas

Abstract

The invention provides a polyester fabric base canvas drying method which comprises the following steps: providing a polyester fabric base canvas, and performing water squeezing and preheating treatment on the polyester fabric base canvas; then the polyester fabric base canvas is conveyed into a third heating and drying unit, a second heating and drying unit and a first heating and drying unit in sequence, so that the polyester fabric base canvas is subjected to steam heating and drying treatment in the third heating and drying unit and the second heating and drying unit; steam in the polyester fibers is replaced by dry air in the first heating and drying unit. According to the drying method of the polyester fabric-based canvas, provided by the invention, steam in the polyester fabric-based canvas is replaced by dry air, so that the polyester fabric-based canvas does not have steam condensate water residues; and the canvas is dried by utilizing the dry air, so that a steam generator is not needed, and the energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of drying, in particular to a drying method for a polyester fabric-based canvas. Background Art

[0002] Traditional canvases mainly use linen as the base material, but linen has some defects. For example, linen is easy to breed bacteria, causing the canvas to mold; during industrial processing, linen needs to be dehydrated and dried, but linen has poor high temperature resistance. When the temperature exceeds 130°C, the linen will partially denature (when the temperature reaches 150°C, it will mostly or even completely denature), and its performance will decrease.

[0003] With the continuous innovation of technology, polyester is increasingly used in the production process of canvas. Polyester fibers are dense and have better high temperature resistance (can reach nearly 200°C, and can still maintain its own good performance under heating conditions of 150°C). In recent years, Jiangsu Phoenix Art Materials Technology Co., Ltd. has applied for multiple patent applications for polyester fabric-based canvases, including a type of rice paper disclosed in patent publication number CN117738024A (2023 application) and a recyclable canvas disclosed in patent publication number CN118292286A (2024 application).

[0004] Although polyester has better high temperature resistance and can be used for high temperature dehydration, due to the dense characteristics of polyester fibers, the gaps between polyester fibers are small. During the high temperature steam dehydration process, high temperature steam will still remain in the gaps between polyester fibers. After the polyester fabric-based canvas leaves the dehydration environment, it will enter the atmosphere. Under the alternating effects of the hot and cold atmosphere, the steam in the gaps between the polyester fibers will cool and condense to form tiny water droplets. Due to the dense characteristics of polyester fibers, these tiny water droplets are difficult to evaporate and dry quickly, resulting in long-term residual moisture in the polyester fibers. This moisture will become soil for the growth of bacteria, which can easily cause the canvas to mildew.

[0005] Based on this technical status, it is necessary to solve the problem that some moisture still remains in the gaps between polyester fibers after the polyester fabric-based canvas is dehydrated with high-temperature steam. Summary of the invention

[0006] The technical problem to be solved by the embodiments of the present invention is to provide a drying method for polyester fabric-based canvas, which does not use a separate steam generating device, but utilizes the evaporation of moisture in the canvas itself to perform high-temperature drying on the canvas, and uses dry air to replace the steam in the gaps between polyester fibers before the end, so that the polyester fibers no longer have residual steam moisture, thereby solving the problem that moisture still remains in the gaps between polyester fibers after conventional steam-heated polyester drying.

[0007] In order to solve the above technical problems, the present invention provides a method for drying a polyester fabric-based canvas, comprising: Step 1, providing a polyester fabric-based canvas, squeezing water from the polyester fabric-based canvas and preheating the canvas to make the temperature of the polyester fabric-based canvas reach T2; Step 2: transport the polyester fabric-based canvas into the third heating and drying unit, and perform steam heating and drying treatment on the polyester fabric-based canvas in a temperature environment not exceeding 150° C.; Step 3: transport the polyester fabric-based canvas into the second heating and drying unit, and perform steam heating and drying treatment on the polyester fabric-based canvas in a temperature environment not exceeding 130° C.; Step 4: convey the polyester fabric-based canvas into the first heating and drying unit, so that the polyester fabric-based canvas replaces steam in the polyester fibers with dry air in an environment with a temperature not exceeding 110° C.

[0008] In the step 1, the polyester fabric-based canvas is squeezed and preheated by a roller squeezing and heating device.

[0009] According to the temperature change information of the polyester fabric-based canvas before and after squeezing, the moisture content of the polyester fabric-based canvas after squeezing is evaluated; According to the evaluation result of the moisture content, the drying temperatures in the second heating and drying unit and the third heating and drying unit are corrected.

[0010] Among them: the moisture content of the polyester fabric-based canvas after squeezing is evaluated, including: Obtaining the temperature T1 of the polyester fabric-based canvas before squeezing, the heating temperature T0 of the roller squeezing heating device, and the temperature T2 of the polyester fabric-based canvas after squeezing; Temperature T1 may be an ambient temperature (such as room temperature), or may be a temperature after preheating the polyester fabric-based canvas before squeezing out water, and needs to satisfy T1+20<T0, that is, T1 is at least 20°C lower than T0, so as to better evaluate the moisture content of the polyester fabric-based canvas after squeezing out water; Temperature T0 is the temperature of the surface of the heating roller in the roller squeeze water heating device. T0 is usually a set value and is fixed. For example, it can take any value between 80-100°C. Temperature T2 is the temperature of the surface of the polyester fabric-based canvas that is not in contact with the heating roller after squeezing water; According to the three temperature parameters of T1, T2 and T0, the moisture content of the polyester fabric-based canvas after squeezing was evaluated.

[0011] The method for evaluating the moisture content of polyester fabric-based canvas after squeezing is: Under the premise that the conveying rate of polyester fabric-based canvas is fixed, the differences of T0-T1 and T2-T1 are calculated respectively; Determine the moisture content coefficient γ = (T2-T1) 2 / (T0-T1) 2 , since T2 must be smaller than T0 and larger than T1, the value range of γ is 0<γ<1; The moisture content is determined based on the value of γ: the larger the value, the lower the moisture content; the smaller the value, the higher the moisture content.

[0012] Among them, when the pressure roller and the support roller of the roller-pressed water squeezing and heating device are placed horizontally, the polyester fabric-based canvas passes vertically upward between the pressure roller and the support roller, and is horizontally transmitted along the support roller into the high-temperature drying box. At this time, due to the increase in the contact area between the polyester fabric-based canvas and the support roller, the temperature T2 of the polyester fabric-based canvas after squeezing water and the temperature T0 of the heating roller of the roller-pressed water squeezing and heating device need to meet the following conditions: T2+5<T0; that is, a temperature difference of at least 5°C is maintained between T2 and T0, so that the moisture content of the polyester fabric-based canvas after squeezing can be effectively evaluated.

[0013] According to the evaluation result of the moisture content, the drying temperature in the second heating and drying unit and the third heating and drying unit is corrected, including: According to the moisture content coefficient γ, the heating temperature Tb of the second heating and drying unit is adjusted. Tb=100+10 / γ, and the maximum value of Tb is guaranteed not to exceed 130℃; According to the moisture content coefficient γ, the heating temperature Tc of the third heating and drying unit is adjusted. Tb=100+15 / γ, and ensure that the maximum Tc value does not exceed 150℃.

[0014] For the heating temperature Ta of the first heating and drying unit, a constant temperature is adopted, and the temperature can be set between 80-110°C.

[0015] And, according to the conveying speed v of the polyester fabric-based canvas, the distance L between the canvas entrance of the second heating and drying unit and the canvas entrance of the third heating and drying unit, the heating device of the second heating and drying unit is delayed controlled, wherein: The delay control time of the second heating and drying unit is t, t=L / v; To ensure that the power of the heating device in the second heating and drying unit is adjusted in advance before the polyester fabric-based canvas passes through the support roller and enters the second heating and drying unit, thereby providing pretreatment time for the drying of the polyester fabric-based canvas and avoiding temperature control conflicts with the polyester fabric-based canvas in other areas.

[0016] Wherein, when the pressure roller and the support roller of the roller squeeze water heating device are placed horizontally, step one further comprises: A wastewater collecting device is arranged below the pressure roller and the support roller, and the water squeezed out from the polyester fabric-based canvas is collected through the wastewater collecting device.

[0017] Step 1 also includes, when T2+1≥T0, controlling the cylinder rod of the telescopic cylinder to extend in a step-by-step manner, with the time interval of each extension being πr / 2v, until T2+5<T0, keeping the cylinder rod of the telescopic cylinder stationary; Where r is the radius of the support roller, and v is the conveying speed of the polyester fabric-based canvas.

[0018] The air outlet of the first heating and drying unit is connected with the air inlet of the second heating and drying unit, so that the dry gas of the first heating and drying unit can be passed into the second heating and drying unit; the air outlet of the second heating and drying unit is connected with the air inlet of the third heating and drying unit, so that the high-temperature steam of the second heating and drying unit can be passed into the third heating and drying unit. The polyester fabric-based canvas passes through the third heating and drying unit, the second heating and drying unit, and the first heating and drying unit in sequence, thereby forming a reverse flow operation between the polyester fabric-based canvas and the three heating and drying units.

[0019] The air inlet of each heating and drying unit is located at the bottom, and the air outlet is located at the top.

[0020] The air inlet of the first heating and drying unit is connected to the air inlet pipe; The air outlet of the first heating and drying unit is connected to the air inlet of the second heating and drying unit through a first air pipeline; The air outlet of the second heating and drying unit is connected to the air inlet of the third heating and drying unit through a second air pipeline; The air outlet of the third heating and drying unit is communicated with the air outlet pipe.

[0021] The first gas pipeline and the second gas pipeline are arranged in a semi-circular manner along the outer wall of the high-temperature drying box.

[0022] The first heating and drying unit and the second heating and drying unit, as well as the second heating and drying unit and the third heating and drying unit are separated by partitions.

[0023] The dry gas is unheated but filtered air at room temperature.

[0024] Each heating and drying unit is provided with a heating device, and the heating device is arranged on the upper and lower sides of the polyester fabric-based canvas to heat the polyester fabric-based canvas through the surfaces of both sides.

[0025] The heating device includes a first heating plate arranged above the polyester fabric-based canvas, a plurality of first heating rods evenly distributed on the first heating plate, a second heating plate arranged below the polyester fabric-based canvas, a plurality of second heating rods evenly distributed on the second heating plate, and a plurality of air holes evenly distributed on the first heating plate and the second heating plate, respectively, so that air can flow from bottom to top.

[0026] The drying method of the polyester fabric-based canvas provided by the present invention replaces the steam in the polyester fabric-based canvas by dry air, so that the polyester fabric-based canvas does not have residual moisture due to steam condensation; the canvas is dried by dry air, so that a steam generator is not required, thereby reducing energy consumption; before drying, the polyester fabric-based canvas is subjected to a water squeezing and heating treatment, and the moisture content is determined according to the temperature of the canvas after squeezing and heating, and then the temperature of the heating and drying process is adjusted according to the moisture content, thereby further achieving an energy-saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a drying system for polyester fabric-based canvas; Figure 2 It is a schematic diagram of three heating and drying units and the direction of the canvas in the drying system of polyester fabric-based canvas; Figure 3 This is a schematic diagram of a structure in which the pressure roller and the support roller of the roller squeeze water heating device are placed horizontally; Figure 4 For combination Figure 3 Schematic diagram of the structure of the drying system of polyester fabric-based canvas.

[0028] In the figure: 1-high temperature drying box; 1a-canvas inlet; 1b-canvas outlet; 11-first heating and drying unit; 11a-air inlet of the first heating and drying unit; 11b-air outlet of the first heating and drying unit; 12-second heating and drying unit; 12a-air inlet of the second heating and drying unit; 12b-air outlet of the second heating and drying unit; 13-third heating and drying unit; 13a-air inlet of the third heating and drying unit; 13b-air outlet of the third heating and drying unit; 14-intake pipe; 15- first gas transmission pipeline; 16- second gas transmission pipeline; 17-exhaust pipe; 18-heating device; 18a-first heating plate; 18b-second heating plate; 18c-first heating rod; 18d-second heating rod; 19-partition; 2-roller squeeze water heating device; 21-pressure roller; 22-support roller; 23-base; 24-support column; 25-adjusting beam; 26-telescopic cylinder; 27-support shaft seat; 3-Polyester fabric base canvas. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0030] The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] Combination Figure 1-4 As shown, the present invention provides a method for drying a polyester fabric-based canvas, comprising: Step 1, providing a polyester fabric-based canvas 3, squeezing water from the polyester fabric-based canvas 3 and preheating the polyester fabric-based canvas 3 to make the temperature of the polyester fabric-based canvas 3 reach T2; Step 2: transport the polyester fabric-based canvas 3 into the third heating and drying unit 13, so that the polyester fabric-based canvas 3 is subjected to steam heating and drying treatment in a temperature environment not exceeding 150° C.; Step 3: transport the polyester fabric-based canvas 3 into the second heating and drying unit 12, and perform steam heating and drying treatment on the polyester fabric-based canvas 3 in a temperature environment not exceeding 130° C.; Step 4: convey the polyester fabric-based canvas 3 into the first heating and drying unit 11, so that the polyester fabric-based canvas 3 replaces the steam in the polyester fibers with dry air in an environment with a temperature not exceeding 110°C.

[0033] The drying method of the polyester fabric-based canvas provided in the present embodiment can fully dry the polyester fabric-based canvas by means of two high-temperature steam dryings and one dry air replacement, and no condensed water vapor will remain between the polyester fibers of the polyester fabric-based canvas after drying; since the steam in the entire drying process is formed by the evaporation of the water of the canvas itself, there is no need to use external high-temperature steam, so compared with the conventional steam drying process, the drying method provided by the present invention is not only more energy-saving, but also more efficient; the method of squeezing out water and preheating before drying can improve the drying efficiency, and since part of the water is squeezed out, the energy consumed in the drying process is also reduced, and the moisture content of the polyester fabric-based canvas after squeezing out the water is evaluated, and then different drying temperatures are designed for the three units, so as to achieve a good drying effect.

[0034] In the step 1, the polyester fabric-based canvas 3 is squeezed and preheated by the roller squeezing and heating device 2. Squeezing out water does not ensure that the entire polyester fabric-based canvas is free of water, and the extrusion pressure cannot be too large to avoid damaging the material of the polyester fabric-based canvas. Since the steam source used by the second heating and drying unit and the third heating and drying unit is the water contained in the polyester fabric-based canvas itself, a reasonable balance needs to be achieved between the extrusion pressure and the moisture content.

[0035] According to the temperature change information of the polyester fabric-based canvas 3 before and after squeezing water, the moisture content of the polyester fabric-based canvas 3 after squeezing water is evaluated; According to the evaluation result of the moisture content, the drying temperatures in the second heating and drying unit 12 and the third heating and drying unit 13 are corrected.

[0036] Wherein: the moisture content of the polyester fabric-based canvas 3 after squeezing out water is evaluated, including: Obtaining the temperature T1 of the polyester fabric-based canvas 3 before squeezing, the heating temperature T0 of the roller squeezing heating device 2, and the temperature T2 of the polyester fabric-based canvas 3 after squeezing; The temperature T1 may be the ambient temperature (such as room temperature) or the temperature after preheating the polyester fabric-based canvas 3 before squeezing out water, and needs to satisfy T1+20<T0, that is, T1 is at least 20°C lower than T0, so as to better evaluate the moisture content of the polyester fabric-based canvas after squeezing out water; Temperature T0 is the temperature of the surface of the heating roller in the roller squeeze water heating device 2. T0 is usually a set value and is fixed. For example, it can be any value between 80-100°C. Temperature T2 is the temperature of the surface of the polyester fabric-based canvas 3 that is not in contact with the heating roller after squeezing water; According to the three temperature parameters T1, T2 and T0, the moisture content of the polyester fabric-based canvas 3 after squeezing is evaluated.

[0037] The method for evaluating the moisture content of the polyester fabric-based canvas 3 after squeezing water is: Under the premise that the conveying rate of the polyester fabric-based canvas 3 is fixed, the differences of T0-T1 and T2-T1 are calculated respectively; Determine the moisture content coefficient γ = (T2-T1) 2 / (T0-T1) 2 , since T2 must be smaller than T0 and larger than T1, the value range of γ is 0<γ<1; The moisture content is determined based on the value of γ: the larger the value, the lower the moisture content; the smaller the value, the higher the moisture content.

[0038] Among them, when the pressure roller 21 and the support roller 22 of the roller-pressed water squeezing and heating device 2 are placed horizontally, the polyester fabric-based canvas 3 passes vertically upward between the pressure roller 21 and the support roller 22, and is horizontally transmitted along the support roller 22 into the high-temperature drying box. At this time, due to the increase in the contact area between the polyester fabric-based canvas 3 and the support roller 22, the temperature T2 of the polyester fabric-based canvas 3 after squeezing water and the temperature T0 of the heating roller (that is, the support roller 22) of the roller-pressed water squeezing and heating device 2 need to meet the following conditions: T2+5<T0; that is, a temperature difference of at least 5°C is maintained between T2 and T0, so that the moisture content of the polyester fabric-based canvas 3 after squeezing water can be effectively evaluated.

[0039] According to the evaluation result of the moisture content, the drying temperature in the second heating and drying unit 12 and the third heating and drying unit 13 is corrected, including: According to the moisture content coefficient γ, the heating temperature Tb of the second heating and drying unit 12 is adjusted. Tb=100+10 / γ, and the maximum value of Tb is guaranteed not to exceed 130℃; According to the moisture content coefficient γ, the heating temperature Tc of the third heating and drying unit 13 is adjusted. Tb=100+15 / γ, and ensure that the maximum Tc value does not exceed 150℃.

[0040] As for the heating temperature Ta of the first heating and drying unit 11, a constant temperature is adopted, and the temperature can be set between 80-110°C.

[0041] And, according to the conveying speed v of the polyester fabric-based canvas 3 and the distance L between the canvas entrance of the second heating and drying unit 12 and the canvas entrance of the third heating and drying unit 13, the heating device of the second heating and drying unit 12 is delayed controlled, wherein: The delay control time of the second heating and drying unit 12 is t, t=L / v; To ensure that the power of the heating device in the second heating and drying unit 12 is adjusted in advance before the polyester fabric-based canvas 3 passing through the support roller 22 enters the second heating and drying unit 12, thereby providing pretreatment time for drying the polyester fabric-based canvas 3, while avoiding conflicts with the temperature control of the polyester fabric-based canvas 3 in other areas.

[0042] Wherein, when the pressure roller 21 and the support roller 22 of the roller squeeze water heating device 2 are placed horizontally (wherein the horizontal placement means: the axes of the pressure roller 21 and the support roller 22 are located in the same horizontal plane; the opposite is the vertical placement, that is, the axes of the pressure roller 21 and the support roller 22 are located in the same vertical plane), step one also includes: A wastewater collecting device is arranged below the pressure roller 21 and the support roller 22, and the water squeezed out from the polyester fabric-based canvas 3 is collected by the wastewater collecting device.

[0043] The roller squeeze water heating device 2 also includes a base 23, a supporting column 24, an adjusting beam 25, a telescopic cylinder 26 and a supporting shaft seat 27, wherein the pressure roller is installed on the adjusting beam 25, the supporting roller 22 is installed on the base 23 through the supporting shaft seat 27, and the supporting column and the telescopic cylinder are located on both sides of the pressure roller and the supporting roller, and the supporting column and the telescopic cylinder connect the adjusting beam 25 and the base 23.

[0044] When the pressure roller 21 and the support roller 22 of the roller-pressed water-squeezing and heating device 2 are placed horizontally, the adjusting beam 25 and the telescopic cylinder 26 therein are placed horizontally; when the pressure roller 21 and the support roller 22 of the roller-pressed water-squeezing and heating device 2 are placed vertically, the adjusting beam 25 and the telescopic cylinder 26 therein are placed vertically.

[0045] A pressure sensor is also provided between the support shaft seat 27 and the base for detecting the pressure change between the pressure roller and the support roller. The pressure change indicates the change in the squeezing force of the polyester fabric-based canvas by the pressure roller and the support roller. When the squeezing force between the two exceeds a preset value, the telescopic cylinder 26 releases the cylinder rod to reduce the squeezing force. The preset value of the squeezing force is a limit value to ensure that the polyester fabric-based canvas is not squeezed and damaged.

[0046] Step 1 also includes, when T2+1≥T0, controlling the cylinder rod of the telescopic cylinder to extend in a step-by-step manner, after each extension and retraction control of the cylinder, the detection time interval is πr / 2v, and correspondingly, the time interval of each extension is πr / 2v, until T2+5<T0, keeping the cylinder rod of the telescopic cylinder stationary; Wherein r is the radius of the support roller 22, and v is the conveying speed of the polyester fabric-based canvas 3.

[0047] This step can control the interval between the movement and detection of the telescopic cylinder to πr / 2v, so that the change in moisture content of the polyester fabric-based canvas after the cylinder movement is completed can be accurately detected.

[0048] The air outlet of the first heating and drying unit is connected with the air inlet of the second heating and drying unit, so that the dry gas of the first heating and drying unit 11 can be passed into the second heating and drying unit 12; the air outlet of the second heating and drying unit is connected with the air inlet of the third heating and drying unit, so that the high-temperature steam of the second heating and drying unit 12 can be passed into the third heating and drying unit 13. The polyester fabric-based canvas 3 passes through the third heating and drying unit 13, the second heating and drying unit 12, and the first heating and drying unit 11 in sequence, thereby forming a counter-flow operation between the polyester fabric-based canvas 3 and the three heating and drying units.

[0049] The air inlet of each heating and drying unit is located at the bottom, and the air outlet is located at the top.

[0050] The air inlet of the first heating and drying unit is connected to the air inlet pipe 14; The air outlet of the first heating and drying unit is connected to the air inlet of the second heating and drying unit through the first air pipeline 15; The air outlet of the second heating and drying unit is connected to the air inlet of the third heating and drying unit through the second air pipeline 16; The air outlet of the third heating and drying unit is communicated with the air outlet pipe 17 .

[0051] The first gas pipeline 15 and the second gas pipeline 16 are arranged in a semi-circular manner along the outer wall of the high-temperature drying box.

[0052] The first heating and drying unit 11 and the second heating and drying unit 12 , and the second heating and drying unit 12 and the third heating and drying unit 13 are separated by a partition 19 .

[0053] The dry gas is unheated but filtered air at room temperature.

[0054] Each heating and drying unit is provided with a heating device, and the heating device is arranged on the upper and lower sides of the polyester fabric-based canvas 3 to heat the polyester fabric-based canvas 3 through the surfaces of both sides.

[0055] The heating device includes a first heating plate 18a arranged above the polyester fabric-based canvas 3, a plurality of first heating rods 18c evenly distributed on the first heating plate 18a, a second heating plate 18b arranged below the polyester fabric-based canvas 3, and a plurality of second heating rods 18d evenly distributed on the second heating plate 18b. A plurality of air holes are evenly distributed on the first heating plate 18a and the second heating plate 18b, respectively, so that air can flow from bottom to top.

[0056] The drying method of the polyester fabric-based canvas 3 provided by the present invention replaces the steam in the polyester fabric-based canvas 3 with dry air, so that the polyester fabric-based canvas 3 does not have residual moisture due to steam condensation; the canvas is dried with dry air, so that a steam generator is not required, thereby reducing energy consumption; before drying, the polyester fabric-based canvas 3 is subjected to a water squeezing and heating treatment, and the moisture content is determined based on the temperature of the canvas after squeezing and heating, and then the temperature of the heating and drying process is adjusted based on the moisture content, thereby further achieving an energy-saving effect.

[0057] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for drying a polyester fabric-based canvas, characterized in that: include: Step 1, providing a polyester fabric-based canvas, squeezing water from the polyester fabric-based canvas and preheating the canvas to make the temperature of the polyester fabric-based canvas reach T2; Step 2: transport the polyester fabric-based canvas into the third heating and drying unit, and perform steam heating and drying treatment on the polyester fabric-based canvas in a temperature environment not exceeding 150° C.; Step 3: transport the polyester fabric-based canvas into the second heating and drying unit, and perform steam heating and drying treatment on the polyester fabric-based canvas in a temperature environment not exceeding 130° C.; Step 4: convey the polyester fabric-based canvas into the first heating and drying unit, so that the polyester fabric-based canvas replaces steam in the polyester fibers with dry air in an environment with a temperature not exceeding 110° C.

2. The drying method according to claim 1, characterized in that: In the step 1, the polyester fabric-based canvas is squeezed and preheated by a roller squeezing and heating device.

3. The drying method according to claim 1, characterized in that: According to the temperature change information of the polyester fabric-based canvas before and after squeezing, the moisture content of the polyester fabric-based canvas after squeezing is evaluated; According to the evaluation result of the moisture content, the drying temperatures in the second heating and drying unit and the third heating and drying unit are corrected.

4. The drying method according to claim 3, characterized in that: in: The moisture content of polyester fabric-based canvas after squeezing is evaluated, including: Obtaining the temperature T1 of the polyester fabric-based canvas before squeezing, the heating temperature T0 of the roller squeezing heating device, and the temperature T2 of the polyester fabric-based canvas after squeezing; Temperature T1 is the ambient temperature or the temperature T1 is the temperature after preheating the polyester fabric-based canvas before squeezing water, and needs to satisfy T1+20<T0, that is, T1 is at least 20°C lower than T0, so as to better evaluate the moisture content of the polyester fabric-based canvas after squeezing water; Temperature T0 is the temperature of the surface of the heating roller in the roller squeeze water heating device. T0 is a set value and is fixed; Temperature T2 is the temperature of the surface of the polyester fabric-based canvas that is not in contact with the heating roller after squeezing water; According to the three temperature parameters of T1, T2 and T0, the moisture content of the polyester fabric-based canvas after squeezing was evaluated.

5. The drying method according to claim 4, characterized in that: The method for evaluating the moisture content of polyester fabric-based canvas after squeezing is: Under the premise that the conveying rate of polyester fabric-based canvas is fixed, the differences of T0-T1 and T2-T1 are calculated respectively; Determine the moisture content coefficient γ = (T2-T1) 2 / (T0-T1) 2 , since T2 must be smaller than T0 and larger than T1, the value range of γ is 0<γ<1; The moisture content is determined based on the value of γ: the larger the value, the lower the moisture content; the smaller the value, the higher the moisture content.

6. The drying method according to claim 5, characterized in that: in, When the pressure roller and the support roller of the roller-pressed water squeezing and heating device are placed horizontally, the polyester fabric-based canvas passes vertically upward between the pressure roller and the support roller, and is horizontally transmitted along the support roller into the high-temperature drying box. At this time, due to the increase in the contact area between the polyester fabric-based canvas and the support roller, the temperature T2 of the polyester fabric-based canvas after squeezing water and the temperature T0 of the heating roller of the roller-pressed water squeezing and heating device need to meet the following conditions: T2+5<T0; that is, a temperature difference of at least 5°C is maintained between T2 and T0, so that the moisture content of the polyester fabric-based canvas after squeezing can be effectively evaluated.

7. The drying method according to claim 3, characterized in that: in, According to the evaluation result of the moisture content, the drying temperature in the second heating and drying unit and the third heating and drying unit is corrected, including: According to the moisture content coefficient γ, the heating temperature Tb of the second heating and drying unit is adjusted. Tb=100+10 / γ, and the maximum value of Tb is guaranteed not to exceed 130℃; According to the moisture content coefficient γ, the heating temperature Tc of the third heating and drying unit is adjusted. Tb=100+15 / γ, and ensure that the maximum Tc value does not exceed 150℃.

8. The drying method according to claim 7, characterized in that: For the heating temperature Ta of the first heating and drying unit, a constant temperature is adopted, and the temperature is set between 80-110°C.

9. The drying method according to claim 8, characterized in that: According to the conveying speed v of the polyester fabric-based canvas and the distance L between the canvas entrance of the second heating and drying unit and the canvas entrance of the third heating and drying unit, the heating device of the second heating and drying unit is delayed controlled, wherein: The delay control time of the second heating and drying unit is t, t=L / v; To ensure that the power of the heating device in the second heating and drying unit is adjusted in advance before the polyester fabric-based canvas passes through the support roller and enters the second heating and drying unit, thereby providing pretreatment time for the drying of the polyester fabric-based canvas and avoiding temperature control conflicts with the polyester fabric-based canvas in other areas.

10. The drying method according to any one of claims 1 to 9, characterized in that: in, When the pressure roller and the support roller of the roller squeeze water heating device are placed horizontally, step one further comprises: A wastewater collecting device is arranged below the pressure roller and the support roller, and the water squeezed out from the polyester fabric-based canvas is collected through the wastewater collecting device.

11. The drying method according to claim 10, characterized in that: Step 1 also includes, when T2+1≥T0, controlling the cylinder rod of the telescopic cylinder to extend in a step-by-step manner, with the time interval of each extension being πr / 2v, until T2+5<T0, keeping the cylinder rod of the telescopic cylinder stationary; Where r is the radius of the support roller, and v is the conveying speed of the polyester fabric-based canvas.

12. The drying method according to any one of claims 1 to 9, characterized in that: The air outlet of the first heating and drying unit is connected with the air inlet of the second heating and drying unit, so that the dry gas of the first heating and drying unit can be passed into the second heating and drying unit; the air outlet of the second heating and drying unit is connected with the air inlet of the third heating and drying unit, so that the high-temperature steam of the second heating and drying unit can be passed into the third heating and drying unit. The polyester fabric-based canvas passes through the third heating and drying unit, the second heating and drying unit, and the first heating and drying unit in sequence, thereby forming a reverse flow operation between the polyester fabric-based canvas and the three heating and drying units.

13. The drying method according to claim 12, characterized in that: The air inlet of each heating and drying unit is located at the bottom, and the air outlet is located at the top.

14. The drying method according to claim 12, characterized in that: The air inlet of the first heating and drying unit is connected to the air inlet pipe; The air outlet of the first heating and drying unit is connected to the air inlet of the second heating and drying unit through a first air pipeline; The air outlet of the second heating and drying unit is connected to the air inlet of the third heating and drying unit through a second air pipeline; The air outlet of the third heating and drying unit is communicated with the air outlet pipe.

15. The drying method according to claim 14, characterized in that: The first gas pipeline and the second gas pipeline are arranged in a semi-circular manner along the outer wall of the high-temperature drying box.

16. The drying method according to claim 12, characterized in that: The first heating and drying unit and the second heating and drying unit, as well as the second heating and drying unit and the third heating and drying unit are separated by partitions.

17. The drying method according to claim 12, characterized in that: The dry gas is unheated but filtered air at room temperature.

18. The drying method according to claim 12, characterized in that: Each heating and drying unit is provided with a heating device, and the heating device is arranged on the upper and lower sides of the polyester fabric-based canvas to heat the polyester fabric-based canvas through the surfaces of both sides.

19. The drying method according to claim 18, characterized in that: The heating device includes a first heating plate arranged above the polyester fabric-based canvas, a plurality of first heating rods evenly distributed on the first heating plate, a second heating plate arranged below the polyester fabric-based canvas, a plurality of second heating rods evenly distributed on the second heating plate, and a plurality of air holes evenly distributed on the first heating plate and the second heating plate, respectively, so that air can flow from bottom to top.

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