Drying Method for Polyester Fabric-Based Canvas

Abstract

The present invention provides a drying method for a canvas based on polyester fabric, which includes: providing a canvas based on polyester fabric, squeezing water from the canvas based on polyester fabric and performing a preheating treatment; then successively conveying the canvas based on polyester fabric into a third heating and drying unit, a second heating and drying unit, and a first heating and drying unit, so that the canvas based on polyester fabric undergoes steam heating and drying treatment in the third heating and drying unit and the second heating and drying unit, and steam in polyester fibers is displaced by dry air in the first heating and drying unit. The drying method for the canvas based on polyester fabric provided by the present invention displaces the steam in the canvas based on polyester fabric by dry air, so that there is no residual steam condensation moisture in the canvas based on polyester fabric; the canvas is dried by using dry air, so that a steam generator is not required, and the energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of drying, and particularly to a drying method for a canvas based on polyester fabric. Background Art

[0002] Traditional canvases mainly use linen as the base material, but linen has some defects. For example, linen is prone to bacterial growth, leading to canvas mildew; during industrial processing of linen, dehydration and drying treatments are required, but linen has poor high-temperature resistance. When the temperature exceeds 130°C, linen will undergo partial denaturation (when the temperature reaches 150°C, most or even completely denature), and its performance deteriorates.

[0003] With the continuous innovation of technology, polyester is increasingly applied to the production process of canvases. Polyester fibers are dense and have better high-temperature resistance (it can reach up to nearly 200°C, and still maintain its good performance under the heating condition 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 kind of rice paper-like canvas disclosed in the patent publication number CN117738024A (applied in 2023) and a recyclable canvas disclosed in the patent publication number CN118292286A (applied in 2024).

[0004] Although polyester has better high-temperature resistance and can be used for high-temperature dehydration treatment, due to the dense characteristics of polyester fibers, the gaps between polyester fibers are small. During the process of high-temperature steam dehydration treatment, there will still be residual high-temperature steam in the gaps of polyester fibers. After the polyester fabric-based canvas leaves the dehydration environment, it will enter the atmospheric environment. Under the alternating action of heat and cold in the atmospheric environment, the steam in the gaps of 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 quickly evaporate and dry, resulting in possible long-term residual moisture in polyester fibers. These moisture will become the soil for bacterial growth and easily lead to canvas mildew.

[0005] Based on this technical status quo, it is necessary to solve the problem that there is still some moisture remaining in the gaps of polyester fibers after high-temperature steam dehydration of polyester fabric-based canvases. 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 a polyester fabric-based canvas, which does not use a separate steam generating device, but uses the evaporation of the moisture in the canvas itself to perform high-temperature drying on the canvas, and uses dry air to displace the steam in the gaps of polyester fibers before the end, so that no steam moisture remains in the polyester fibers, thereby solving the problem that there is still moisture remaining in the gaps of polyester fibers after conventional steam heating and drying of polyester.

[0007] To solve the above technical problems, the present invention provides a drying method for a canvas based on polyester fabric, including:

[0008] Step 1: Provide a canvas based on polyester fabric, and perform water squeezing and preheating treatment on the canvas based on polyester fabric to make the temperature of the canvas based on polyester fabric reach T2;

[0009] Step 2: Convey the canvas based on polyester fabric into the third heating and drying unit, and perform steam heating and drying treatment on the canvas based on polyester fabric in a temperature environment not exceeding 150°C;

[0010] Step 3: Convey the canvas based on polyester fabric into the second heating and drying unit, and perform steam heating and drying treatment on the canvas based on polyester fabric in a temperature environment not exceeding 130°C;

[0011] Step 4: Convey the canvas based on polyester fabric into the first heating and drying unit, and replace the steam in the polyester fibers with dry air for the canvas based on polyester fabric in a temperature environment not exceeding 110°C.

[0012] In the said Step 1, water squeezing and preheating treatment are performed on the canvas based on polyester fabric through a roll pressing water squeezing and heating device.

[0013] Evaluate the moisture content of the canvas based on polyester fabric after water squeezing according to the temperature change information of the canvas based on polyester fabric before and after water squeezing;

[0014] Correct the drying temperatures in the second heating and drying unit and the third heating and drying unit according to the evaluation result of the moisture content.

[0015] Among them: Evaluating the moisture content of the canvas based on polyester fabric after water squeezing includes:

[0016] Obtain the temperature T1 of the canvas based on polyester fabric before water squeezing, the heating temperature T0 of the roll pressing water squeezing and heating device, and the temperature T2 of the canvas based on polyester fabric after water squeezing;

[0017] The temperature T1 can be the ambient temperature (such as room temperature), and the temperature T1 can also be the temperature after preheating the canvas based on polyester fabric before water squeezing, and it is required 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 canvas based on polyester fabric after water squeezing;

[0018] The temperature T0 is the temperature of the surface of the heating roll in the roll pressing water squeezing and heating device. T0 is usually a set value and remains unchanged. For example, any value between 80 - 100°C can be taken;

[0019] The temperature T2 is the temperature of the surface of the side of the canvas based on polyester fabric that is not in contact with the heating roll after water squeezing;

[0020] Evaluate the moisture content of the polyester fabric-based canvas after water squeezing according to the three temperature parameters T1, T2, and T0.

[0021] The method for evaluating the moisture content of the polyester fabric-based canvas after water squeezing is as follows:

[0022] On the premise that the conveying rate of the polyester fabric-based canvas is fixed, calculate the differences between T0 - T1 and T2 - T1 respectively;

[0023] Determine the moisture content coefficient γ = (T2 - T1) 2 / (T0 - T1) 2 , since T2 must be less than T0 and both are greater than T1, the value range of γ is 0 < γ < 1;

[0024] Judge the moisture content according to the value of γ: the larger the value, the lower the moisture content; the smaller the value, the higher the moisture content.

[0025] Among them, when the pressure roller and the support roller of the roll press water squeezing and heating device are horizontally placed, the polyester fabric-based canvas passes vertically upward between the pressure roller and the support roller and is horizontally transported along the support roller into the high-temperature drying box. At this time, due to the increased contact area between the polyester fabric-based canvas and the support roller, the temperature T2 of the polyester fabric-based canvas after water squeezing and the temperature T0 of the heating roller of the roll press water squeezing and heating device need to meet the following conditions:

[0026] T2 + 5 < T0; that is, there is at least a 5°C temperature difference between T2 and T0 to effectively evaluate the moisture content of the polyester fabric-based canvas after water squeezing.

[0027] Among them, according to the evaluation result of the moisture content, correct the drying temperature in the second heating and drying unit and the third heating and drying unit, including:

[0028] Adjust the heating temperature Tb of the second heating and drying unit according to the moisture content coefficient γ,

[0029] Tb = 100 + 10 / γ, and ensure that the maximum value of Tb does not exceed 130°C;

[0030] Adjust the heating temperature Tc of the third heating and drying unit according to the moisture content coefficient γ,

[0031] Tc = 100 + 15 / γ, and ensure that the maximum value of Tc does not exceed 150°C.

[0032] For the heating temperature Ta of the first heating and drying unit, use a constant temperature, and the temperature can be set between 80 - 110°C.

[0033] And, according to the conveying speed v of the polyester fabric-based canvas and the distance L between the canvas inlet of the second heating and drying unit and the canvas inlet of the third heating and drying unit, perform delay control on the heating device of the second heating and drying unit, where:

[0034] The delay control time for the second heating and drying unit is t, and t = L / v;

[0035] To ensure that before the polyester fabric-based canvas passes through the support rollers and enters the second heating and drying unit, the power of the heating device in the second heating and drying unit is adjusted in advance, so as to provide a pretreatment time for the drying of the polyester fabric-based canvas, and at the same time avoid conflicts in temperature control with the polyester fabric-based canvas in other areas.

[0036] Wherein, when the pressure roller and the support roller of the roll pressing and water squeezing heating device are horizontally placed, step one further includes:

[0037] A waste water collection 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 waste water collection device.

[0038] Step one further includes that when T2 + 1 ≥ T0, the cylinder rod of the telescopic cylinder is controlled to extend step by step, and the time interval for each extension is πr / 2v, until T2 + 5 < T0, then keep the cylinder rod of the telescopic cylinder stationary;

[0039] Wherein r is the radius of the support roller and v is the conveying speed of the polyester fabric-based canvas.

[0040] The air outlet of the first heating and drying unit is communicated with the air inlet of the second heating and drying unit, so that the drying gas of the first heating and drying unit is introduced into the second heating and drying unit; the air outlet of the second heating and drying unit is communicated with the air inlet of the third heating and drying unit, so that the high-temperature steam of the second heating and drying unit is introduced 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, so that a reverse flow operation is formed between the polyester fabric-based canvas and the three heating and drying units.

[0041] The air inlet of each heating and drying unit is located below, and the air outlet is located above.

[0042] The air inlet of the first heating and drying unit is communicated with the air inlet pipe;

[0043] The air outlet of the first heating and drying unit is communicated with the air inlet of the second heating and drying unit through the first air pipeline;

[0044] The air outlet of the second heating and drying unit is communicated with the air inlet of the third heating and drying unit through the second air pipeline;

[0045] The air outlet of the third heating and drying unit is communicated with the air outlet pipe.

[0046] The first air pipeline and the second air pipeline are arranged in a semi-surrounding manner along the outer wall of the high-temperature drying box.

[0047] Between the first heating and drying unit and the second heating and drying unit, and between the second heating and drying unit and the third heating and drying unit, they are separated by partition plates.

[0048] The drying gas is normal-temperature air that has not been heated but has been filtered.

[0049] 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 both surfaces.

[0050] 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, and a plurality of second heating rods evenly distributed on the second heating plate. A number of air-permeable holes are also evenly distributed on the first heating plate and the second heating plate respectively, so that air can flow from bottom to top.

[0051] The drying method of the polyester fabric-based canvas provided by the present invention replaces the steam in the polyester fabric-based canvas with dry air, so that the polyester fabric-based canvas does not have residual steam condensation moisture; uses dry air to dry the canvas, thus eliminating the need for a steam generator and reducing energy consumption; performs water squeezing and heating treatment on the polyester fabric-based canvas before drying, judges the moisture content according to the temperature of the canvas after water squeezing and heating, and then adjusts the temperature of the heating and drying link according to the moisture content situation, further achieving the effect of energy saving. Description of the Drawings

[0052] Figure 1 It is a schematic structural diagram of the drying system for the polyester fabric-based canvas;

[0053] Figure 2 It is a schematic diagram of the three heating and drying units and the canvas running direction in the drying system for the polyester fabric-based canvas;

[0054] Figure 3 It is a schematic structural diagram of the pressure roller and the support roller of the roller pressing and water squeezing heating device placed horizontally;

[0055] Figure 4 For combination Figure 3 It is a schematic structural diagram of the drying system for the polyester fabric-based canvas.

[0056] In the figure: 1 - high-temperature drying box; 1a - canvas inlet; 1b - canvas outlet;

[0057] 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;

[0058] 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;

[0059] 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;

[0060] 14 - Inlet pipe;

[0061] 15 - First gas pipeline;

[0062] 16 - Second gas pipeline;

[0063] 17 - Outlet pipe;

[0064] 18 - Heating device; 18a - First heating plate; 18b - Second heating plate; 18c - First heating rod; 18d - Second heating rod;

[0065] 19 - Partition board;

[0066] 2 - Roller pressing and water squeezing heating device; 21 - Pressure roller; 22 - Support roller; 23 - Base; 24 - Support column; 25 - Adjusting crossbeam; 26 - Telescopic cylinder; 27 - Support shaft seat;

[0067] 3 - Polyester fabric base canvas. Detailed implementation manners

[0068] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention is provided in conjunction with the accompanying drawings. Many specific details are set forth in the following description in order to fully understand 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 departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0069] The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein 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.

[0071] Combined Figures 1-4 As shown, the present invention provides a drying method for a canvas based on polyester fabric, including:

[0072] Step 1: Provide a canvas 3 based on polyester fabric, and perform water squeezing and preheating treatment on the canvas 3 based on polyester fabric to make the temperature of the canvas 3 based on polyester fabric reach T2;

[0073] Step 2: Convey the canvas 3 based on polyester fabric into the third heating and drying unit 13, and perform steam heating and drying treatment on the canvas 3 based on polyester fabric in a temperature environment not exceeding 150 °C;

[0074] Step 3: Convey the canvas 3 based on polyester fabric into the second heating and drying unit 12, and perform steam heating and drying treatment on the canvas 3 based on polyester fabric in a temperature environment not exceeding 130 °C;

[0075] Step 4: Convey the canvas 3 based on polyester fabric into the first heating and drying unit 11, and replace the steam in the polyester fibers with dry air in a temperature environment not exceeding 110 °C for the canvas 3 based on polyester fabric.

[0076] The drying method for the canvas based on polyester fabric provided in this embodiment can fully dry the canvas based on polyester fabric through two high-temperature steam drying and one dry air replacement, and there will be no residual condensed water vapor between the polyester fibers of the canvas based on polyester fabric after drying; since the steam in the entire drying process is evaporated from the water in the canvas itself, there is no need to use external high-temperature steam. Therefore, 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 performing water squeezing and preheating treatment before drying can improve the drying efficiency, and at the same time, since part of the water is squeezed out, the energy consumed in the drying process is also reduced. Then, according to the moisture content of the canvas based on polyester fabric after squeezing out the water, different drying temperatures are designed for the three units to achieve a good drying effect.

[0077] In the said Step 1, the canvas 3 based on polyester fabric is subjected to water squeezing and preheating treatment by a roll pressing water squeezing and heating device 2. Squeezing out the water cannot ensure that the entire canvas based on polyester fabric does not contain water, and the squeezing pressure should not be too large to avoid causing destructive pressure on the material of the canvas based on polyester fabric. Since the steam sources used in the second heating and drying unit and the third heating and drying unit are the water contained in the canvas based on polyester fabric itself, a reasonable balance needs to be achieved between the squeezing pressure and the moisture content.

[0078] Evaluate the moisture content of the canvas 3 based on polyester fabric after water squeezing according to the temperature change information of the canvas 3 based on polyester fabric before and after water squeezing;

[0079] 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.

[0080] Among them: Evaluating the moisture content of the polyester fabric-based canvas 3 after water squeezing includes:

[0081] Obtaining the temperature T1 of the polyester fabric-based canvas 3 before water squeezing, the heating temperature T0 of the roll press water squeezing heating device 2, and the temperature T2 of the polyester fabric-based canvas 3 after water squeezing;

[0082] The temperature T1 can be the ambient temperature (such as room temperature), or the temperature after pre-heating the polyester fabric-based canvas 3 before water squeezing, and it is required 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 water squeezing;

[0083] The temperature T0 is the temperature on the surface of the heating roll in the roll press water squeezing heating device 2. T0 is usually a set value and remains fixed. For example, it can take any value between 80 - 100 °C;

[0084] The temperature T2 is the temperature on the surface of the side of the polyester fabric-based canvas 3 that is not in contact with the heating roll after water squeezing;

[0085] According to the three temperature parameters T1, T2, and T0, the moisture content of the polyester fabric-based canvas 3 after water squeezing is evaluated.

[0086] The method for evaluating the moisture content of the polyester fabric-based canvas 3 after water squeezing is:

[0087] On the premise that the conveying rate of the polyester fabric-based canvas 3 is fixed, calculate the differences between T0 - T1 and T2 - T1 respectively;

[0088] Determine the moisture content coefficient γ = (T2 - T1) 2 / (T0 - T1) 2 , since T2 must be less than T0 and both are greater than T1, the value range of γ is 0 < γ < 1;

[0089] Judge the moisture content according to the value of γ: The larger the value, the lower the moisture content; the smaller the value, the higher the moisture content.

[0090] Among them, when the pressure roller 21 and the support roller 22 of the roll pressing and water squeezing heating device 2 are horizontally placed, the polyester fabric-based canvas 3 passes vertically upward between the pressure roller 21 and the support roller 22 and is horizontally transported along the support roller 22 into the high-temperature drying box. At this time, since the contact area between the polyester fabric-based canvas 3 and the support roller 22 increases, the temperature T2 of the polyester fabric-based canvas 3 after water squeezing and the temperature T0 of the heating roller (i.e., the support roller 22) of the roll pressing and water squeezing heating device 2 need to meet the following conditions:

[0091] T2 + 5 < T0; that is, there is at least a 5°C temperature difference between T2 and T0 to effectively evaluate the moisture content of the polyester fabric-based canvas 3 after water squeezing.

[0092] Among them, 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, including:

[0093] According to the moisture content coefficient γ, the heating temperature Tb of the second heating and drying unit 12 is adjusted,

[0094] Tb = 100 + 10 / γ, and it is ensured that the maximum value of Tb does not exceed 130°C;

[0095] According to the moisture content coefficient γ, the heating temperature Tc of the third heating and drying unit 13 is adjusted,

[0096] Tc = 100 + 15 / γ, and it is ensured that the maximum value of Tc does not exceed 150°C.

[0097] 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.

[0098] And, according to the conveying speed v of the polyester fabric-based canvas 3 and the distance L between the canvas inlet of the second heating and drying unit 12 and the canvas inlet of the third heating and drying unit 13, the heating device of the second heating and drying unit 12 is controlled for delay, where:

[0099] The delay control time for the second heating and drying unit 12 is t, and t = L / v;

[0100] To ensure that before the polyester fabric-based canvas 3 passing through the support roller 22 enters the second heating and drying unit 12, the power of the heating device in the second heating and drying unit 12 is adjusted in advance, so as to provide a pretreatment time for the drying of the polyester fabric-based canvas 3, and at the same time avoid conflicts in temperature control with the polyester fabric-based canvas 3 in other areas.

[0101] Among them, when the pressure roller 21 and the support roller 22 of the rolling and squeezing water heating device 2 are horizontally placed (the horizontal placement here means that the axes of the pressure roller 21 and the support roller 22 are located in the same horizontal plane; in contrast, the vertical placement means that the axes of the pressure roller 21 and the support roller 22 are located in the same vertical plane), step one further includes:

[0102] A waste water collection device is arranged below the pressure roller 21 and the support roller 22, and the water extruded from the polyester fabric-based canvas 3 is collected through the waste water collection device.

[0103] The rolling and squeezing water heating device 2 further includes a base 23, support columns 24, an adjusting cross beam 25, a telescopic cylinder 26 and a support shaft seat 27. The pressure roller is installed on the adjusting cross beam 25, the support roller 22 is installed on the base 23 through the support shaft seat 27, and the support columns and the telescopic cylinder are located on both sides of the pressure roller and the support roller. The support columns and the telescopic cylinder connect the adjusting cross beam 25 and the base 23.

[0104] When the pressure roller 21 and the support roller 22 of the rolling and squeezing water heating device 2 are horizontally placed, the adjusting cross beam 25 and the telescopic cylinder 26 are horizontally placed; when the pressure roller 21 and the support roller 22 of the rolling and squeezing water heating device 2 are vertically placed, the adjusting cross beam 25 and the telescopic cylinder 26 are vertically placed.

[0105] A pressure sensor is further arranged between the support shaft seat 27 and the base, which is used to detect the pressure change between the pressure roller and the support roller. This pressure change represents the change in the extrusion pressure of the polyester fabric-based canvas by the pressure roller and the support roller. Thus, when the extrusion pressure between the two exceeds the preset value, the telescopic cylinder 26 releases the cylinder rod to reduce the extrusion pressure. The preset value of this extrusion pressure is a limit value to ensure that the polyester fabric-based canvas is not damaged by extrusion.

[0106] Step one further includes that when T2 + 1 ≥ T0, the cylinder rod of the telescopic cylinder is controlled to extend step by step. After each control of the telescopic cylinder, the detection time interval is πr / 2v. Correspondingly, the time interval for each extension is πr / 2v until T2 + 5 < T0, and then the cylinder rod of the telescopic cylinder remains stationary;

[0107] Where r is the radius of the support roller 22 and v is the conveying speed of the polyester fabric-based canvas 3.

[0108] This step can control the action of the telescopic cylinder and the detection interval to be πr / 2v, so as to accurately detect the change in the moisture content of the polyester fabric-based canvas after the action of the cylinder is completed.

[0109] The air outlet of the first heating and drying unit is communicated with the air inlet of the second heating and drying unit, so that the drying gas of the first heating and drying unit 11 is introduced into the second heating and drying unit 12; the air outlet of the second heating and drying unit is communicated 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 is introduced into the third heating and drying unit 13. The polyester fabric base 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, so that a reverse flow operation is formed between the polyester fabric base canvas 3 and the three heating and drying units.

[0110] The air inlet of each heating and drying unit is located below, and the air outlet is located above.

[0111] The air inlet of the first heating and drying unit is communicated with the air inlet pipe 14;

[0112] The air outlet of the first heating and drying unit is communicated with the air inlet of the second heating and drying unit through the first air pipe 15;

[0113] The air outlet of the second heating and drying unit is communicated with the air inlet of the third heating and drying unit through the second air pipe 16;

[0114] The air outlet of the third heating and drying unit is communicated with the air outlet pipe 17.

[0115] The first air pipe 15 and the second air pipe 16 are arranged in a semi-surrounding manner along the outer wall of the high-temperature drying box.

[0116] Between the first heating and drying unit 11 and the second heating and drying unit 12, and between the second heating and drying unit 12 and the third heating and drying unit 13, they are separated by a partition plate 19.

[0117] The drying gas is normal-temperature air that has not been heated but has been filtered.

[0118] A heating device is arranged in each heating and drying unit. The heating device is arranged on the upper and lower sides of the polyester fabric base canvas 3 to heat the polyester fabric base canvas 3 through both side surfaces.

[0119] The heating device includes a first heating plate 18a arranged above the polyester fabric base 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 base canvas 3, and a plurality of second heating rods 18d evenly distributed on the second heating plate 18b. A number of ventilation holes are also evenly distributed on the first heating plate 18a and the second heating plate 18b respectively, so that the air flow can flow from bottom to top.

[0120] 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 has no residual steam condensation moisture; the canvas is dried by using dry air, so that a steam generator is not required, and the energy consumption is reduced; before drying, the polyester fabric-based canvas 3 is subjected to water squeezing and heating treatment, and the moisture content is judged according to the temperature of the canvas after water squeezing and heating, and then the temperature of the heating and drying link is adjusted according to the moisture content situation, so as to further achieve the energy-saving effect.

[0121] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0122] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended 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: transport the polyester fabric-based canvas into the first heating and drying unit, so that the polyester fabric-based canvas replaces the steam in the polyester fibers with dry air in an environment with a temperature not exceeding 110° C.; In the step 1, the polyester fabric-based canvas is squeezed and preheated by a roller squeezing and heating device; 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 temperature in the second heating and drying unit and the third heating and drying unit is corrected; 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 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 polyester fabric-based canvas after squeezing was evaluated; 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. The temperature T2 of the polyester fabric-based canvas after squeezing water and the temperature T0 of the heating roller of the roller squeezing 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; 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℃.

2. The drying method according to claim 1, characterized in that: in, When the pressure roller and 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 support roller acts as a heating roller.

3. The drying method according to claim 1, 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.

4. The drying method according to claim 3, 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.

5. The drying method according to any one of claims 1 to 4, 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.

6. The drying method according to claim 5, 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.

7. The drying method according to any one of claims 1 to 4, 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.

8. The drying method according to claim 7, 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.

9. The drying method according to claim 7, 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.

10. The drying method according to claim 9, 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.

11. The drying method according to claim 7, 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.

12. The drying method according to claim 7, characterized in that: The dry gas is unheated but filtered air at room temperature.

13. The drying method according to claim 7, 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.

14. The drying method according to claim 13, 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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