Sectional modified rubber mesh belt hot air drying process

Abstract

The invention relates to a sectional type modified rubber mesh belt hot air drying process which comprises the steps that S1, mesh belt hot air drying equipment is divided into a heating section, a constant-speed drying section and a speed-reducing drying section, and after materials to be dried enter from the feeding end of the equipment and sequentially pass through the heating section, the constant-speed drying section and the speed-reducing drying section, the materials are discharged from the discharging end after being dried; s2, according to the parameters of the to-be-dried material, determining the corresponding material drying temperatures in the temperature rising section, the constant-speed drying section and the speed reduction drying section, and then determining the corresponding hot air temperature and the hot air humidity required to be provided according to the material drying temperature in each section; s3, the air temperature and the air relative humidity in the production environment are detected; and S4, according to the hot air temperature and the hot air humidity required to be provided in each section, and in combination with the air temperature and the air humidity in the production environment, the power value required by a heater used in each section of the mesh belt hot air drying equipment is calculated and adjusted. And the quality of the dried modified rubber is ensured while the drying efficiency of the modified rubber is improved and the drying energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the field of natural rubber drying processing, in particular to a section-type modified rubber mesh belt hot air drying process. Background Art

[0002] As an important strategic basic material for national security and people's livelihood, natural rubber is one of the four major industrial raw materials along with steel, petroleum and coal. It has the dual attributes of agricultural products and industrial products. It is a basic industry related to the national economy and people's livelihood, and is also an important strategic material. Because of its good mechanical strength, low heat generation after multiple deformations, good flex resistance, good electrical insulation, high elasticity, high tensile strength, good tear resistance and wear resistance, and easy adhesion with other materials, it is widely used in the production of industrial products such as tires and tapes, and occupies an irreplaceable position in national defense, military industry, aerospace, rail transportation, marine equipment, etc. With the continuous advancement of science and technology, scientists have found that modified rubber has significantly improved wear resistance, tensile strength, folding resistance, and aging resistance compared to natural rubber. For example, the folding resistance of tire side rubber can be increased from the original 100,000 times to more than 500,000 times. Therefore, research on rubber modification will be the main research hotspot in the rubber industry in the future. Currently, modified rubber in the industry is mainly achieved by adding modified substances into natural rubber to achieve rubber reinforcement. The reinforced rubber often needs to be dried through a mesh belt hot air drying system.

[0003] The heat transfer and dehydration mechanism of the net-belt hot air drying system: the circulating hot air transfers heat to the rubber particles in the process of passing through the material layer. The rubber particles absorb heat and heat up, and some liquid water on their surface vaporizes and enters the hot air. As the surface water of the rubber particles continues to vaporize, the moisture content of the surface tissue decreases, forming a moisture content gradient with the internal tissue, and the internal moisture flows to the surface. Through continuous heat absorption, surface water vaporization, and internal moisture migration outward, the moisture in the material is finally transferred to the hot air to achieve material drying.

[0004] The greater the difference between the initial moisture content and the final moisture content of the modified rubber particles, the longer the drying time and the more heat required; the simpler the microstructure of the rubber particles and the better the heat transfer and moisture diffusion properties, the shorter the drying time and the easier it is to dry; the larger the specific surface area of ​​the rubber particles, the faster the drying rate. At the same time, the hot air humidity reflects that the pressure of the water vapor generated on the surface of the dried rubber particles is greater than the partial pressure of the water vapor in the hot air. The greater the pressure difference, the faster the drying process. When the surface vaporization rate of the rubber particles is greater than the moisture diffusion rate, a moisture gradient is generated in its internal structure and the external structure shrinks, which will make it difficult for the internal water to come out and the external heat to enter, which will seriously affect the drying rate and product quality.

[0005] However, the mesh belt hot air drying equipment currently used is all controlled in one piece, and there is no segmented drying according to the characteristics of the modified rubber. The equipment not only has the disadvantages of high energy consumption, serious heat energy loss, and low drying efficiency, but also the quality of the modified rubber after drying is often difficult to guarantee. Therefore, the existing technology restricts the development of modified rubber, and many scientific researchers have conducted research on mesh belt hot air drying equipment. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a segmented modified rubber mesh belt hot air drying process, which can adjust the front-end material feed flow, the power of the drying heater and the air parameters of the air supply according to the specific characteristics and output of the modified rubber to be dried, thereby improving the drying efficiency of the modified rubber, reducing the drying energy consumption and ensuring the quality of the modified rubber after drying. Specifically, the purpose of the present invention is achieved as follows:

[0007] A sectional modified rubber mesh belt hot air drying process comprises the following steps:

[0008] S1, the net belt hot air drying equipment is divided into a temperature rising section, a constant speed drying section and a speed decreasing drying section;

[0009] S2, according to the parameters of the material to be dried, determine the corresponding material drying temperatures in the heating section, the constant speed drying section and the falling speed drying section, and then determine the corresponding hot air temperature and hot air humidity required to be provided according to the material drying temperature in each section;

[0010] S3, detect the air temperature and relative humidity in the production environment;

[0011] S4, according to the hot air temperature and hot air humidity required in each section, combined with the air temperature and air humidity in the production environment, calculate the power value required by the heater used in each section of the net belt hot air drying equipment, and adjust the power to heat the hot air;

[0012] S5, the material to be dried enters from the feeding end of the mesh belt hot air drying equipment, passes through the heating section, the constant speed drying section and the speed decreasing drying section in sequence, and then is discharged from the discharging end after drying is completed.

[0013] Furthermore, the parameters of the material to be dried include the incoming moisture content W1, the incoming temperature, the outgoing moisture content W2, the outgoing temperature and the outgoing flow rate G; the required feed flow rate can be calculated by the following formula:

[0014]

[0015] Furthermore, the hot air gas in different areas of the mesh belt hot air drying equipment includes 7 states; state 1 is the gas heated by the heater; state 2 is the gas transported by the circulating fan; state 3 is the gas after heat exchange with the rubber material; state 4 is the exhaust gas discharged from the dehumidification port; state 5 is the gas remaining after the exhaust gas is discharged from the dehumidification port; state 6 is the fresh air entering from the air supply port; state 7 is the gas after the fresh air in state 6 is mixed with the gas in state 5; the gas in state 7 becomes the gas in state 1 after passing through the equipment heater; the gas in the 7 states is described by the following parameters, including:

[0016] Q n : Indicates the mass flow rate of dry air in wet air under state n, unit: kg g / h;

[0017] T n : Indicates the Celsius temperature of moist air in state n, unit: ℃;

[0018] d n : Indicates the absolute moisture content of wet air under n conditions, that is, the mass of steam in 1 kg of dry air, unit: kg / kg g ;

[0019] H n : represents the thermal enthalpy of air in state n, unit: kJ / kg; then:

[0020]

[0021] The mass conservation of steam in moist air is:

[0022]

[0023] Assume that the amount of water transferred from the material to the hot air is G s , combined with formula (2):

[0024]

[0025] Assuming that the heat exchange between the heater and the hot air is q1, and the heat exchange between the material and the hot air is q2, according to the law of conservation of energy, we have:

[0026]

[0027] Based on this, it can be obtained that in state 5, state 6 and state 7, the relationship between d and H of the gas is as follows:

[0028]

[0029] From formula (1), we can get:

[0030]

[0031] We can get:

[0032]

[0033] Furthermore, the temperature T of the wet air in state 4 of the exhaust gas discharged from the exhaust outlet is detected by the detection instrument. 4 , absolute moisture content of moist air d 4 ; The relative humidity of the production environment air is recorded as Φ, and the partial pressure P of the steam in the air at this time is calculated by the detected production environment air temperature and air relative humidity W And the saturated water vapor pressure of air P S ; According to the parameters of the material to be dried, the hot air parameters during hot air flow pellet drying include the air flow temperature T, the screen wind speed V, the air flow area S and the hot air density ρ ; x is the material feed flow rate corresponding to the rated production capacity; W 1 is the moisture content of the material feed; G is the material discharge flow rate; W 2 is the moisture content of the material output. According to the law of mass conservation, the required feed flow rate and the amount of water evaporated from the material can be calculated:

[0034]

[0035] Calculate the absolute humidity content d in the production environment air 6 :

[0036]

[0037] According to the air enthalpy formula, the air enthalpy values ​​at state 4 and state 6 can be calculated:

[0038]

[0039] The gas parameters of state 3 and state 5 are consistent with those of state 4, thus:

[0040] H 3 =H 5 =H 4 (11)

[0041] According to the determined hot air parameters, the hot air Q in state 2 can be obtained: 2 :

[0042] Q 2 =S·V(12),

[0043] According to formula (1), we can get:

[0044] Q 3 =Q 7 =Q 1 =Q2 (13)

[0045] From formula (7), we can get the hot air at state 7:

[0046]

[0047] According to formula (2) combined with the thermal enthalpy calculation formula, the hot air in state 2 can be obtained:

[0048]

[0049] Since the hot air is in state 1 and state 2, neither T nor d has changed, so H 1 =H 2 Combining equations (13), (14), (15) and (4), the heater power q required to achieve system drying can be obtained: 1 :

[0050] q 1 =Q 1 (H 2 -H 7 )(16),

[0051] Taking heat loss into consideration, the design power can be:

[0052] q 1 '=1.2×q 1 (17).

[0053] Furthermore, the temperature change of the material from the feed port to the discharge port is divided into three components: A dry rubber particles, B discharge water content, and C rubber particle evaporation water content. 1 The moisture in the material is heated to 100℃, C 2 The water in the material is heated to 100℃ until it vaporizes. 3 After evaporation, water vapor reaches T 3 Water vapor undergoes three changes; then:

[0054]

[0055] In formula (18):

[0056] G g is the mass of dry rubber particles;

[0057] C g is the specific heat of dry rubber particles, which is 2.1 kJ / kg℃;

[0058] C s is the specific heat of water, take 4.2 kJ / kg℃;

[0059] C qis the specific heat of water vapor, taken as 1.53 kJ / kg℃;

[0060] R s is the latent heat of water vaporization, taken as 2257 kJ / kg;

[0061] ΔT is the temperature rise difference between the three changing states;

[0062] q c1 ,q c2 ,q c3 They are the heat exchange corresponding to the three changing processes of evaporation of water in the colloid particles;

[0063] The total heat consumed by the particles from feeding to discharging can be obtained:

[0064] q 2 =q c (19)

[0065] Combining equations (3), (8) and (9), we can get the exhaust gas flow rate in state 4:

[0066]

[0067] The heat in the exhaust gas in state 4 is mainly composed of the heat energy carried by the dry hot air and the heat energy taken away by the steam, that is, from formula (18):

[0068]

[0069] In formula (21): ΔT 41 is the temperature change value of the heat energy carried by the dry wind, ΔT 42 It is the temperature change value of steam carrying heat energy.

[0070] Furthermore, before the drying process, the modified rubber material is preheated to 70°C; the temperature rise section is a stage in which the material temperature rises from 70°C to 100°C; the constant rate drying section is a stage in which the material temperature is maintained at 100°C; and the rate reduction drying section is a stage in which the material temperature decreases from 100°C to 70°C. The moisture content of the material in the temperature rise section is W 1 Gradually decrease, the moisture content does not exceed 10%; the moisture content of the material in the constant speed drying stage gradually decreases from the discharge moisture content of the heating stage to about 10%; the moisture content of the material in the decreasing speed drying stage gradually decreases from about 10% to the discharge moisture content W 2 Finish.

[0071] Furthermore, the temperature of the hot air is maintained at 130℃~140℃ in the heating section; the relative humidity of the hot air in state 3 is maintained at 80%~90%, so that the material is quickly heated up in a high temperature and high humidity environment and a small moisture gradient is maintained between its surface and internal structure; the temperature of the hot air is maintained at 120℃~130℃ in the constant speed drying section; the relative humidity of the hot air in state 3 is maintained at 60%~80%. The hot air temperature mainly provides heat for dehydration of the material, but the temperature cannot exceed 100℃; the hot air temperature in the speed-decreasing drying section gradually decreases from 110℃~120℃ to 80℃; the relative humidity of the hot air in state 3 gradually decreases from 60%~80% to below 10%; under this environmental state, the material temperature gradually decreases from 100℃ to 70℃, and the hot air can remove moisture from the material.

[0072] Furthermore, the state 4 exhaust gas is recovered and used for heat exchange with the heater. The calculated state 4 exhaust gas heat is combined with the original heater required power to recalculate the heater required power, thereby further reducing energy consumption.

[0073] The beneficial effects of the present invention are as follows:

[0074] (I) The present invention can adjust the feed flow rate of the front-end material, the power of the drying heater and the air parameters of the air supply in real time according to the specific characteristics and output of the modified rubber to be dried, so as to achieve a reasonable match between the material dehydration amount, the hot air heat supply, the drying time and the material process temperature. Compared with the traditional rubber hot air drying method, this method shortens the drying time by more than half. The highest temperature of the rubber particles during the drying process is 100°C, which is lower than the traditional 120°C to 130°C, which increases the rubber particles P 0 The value can be increased by more than 20%, the tensile strength can be increased by more than 10%, the Mooney viscosity can be increased by more than 10%, and the hot air energy consumption can be reduced by more than 15%.

[0075] (ii) The present invention monitors the parameters of hot air under various conditions during the drying of the modified rubber through real-time calculation, and divides the drying stage of the modified rubber into a heating stage, a constant-speed drying stage and a speed-decreasing drying stage in combination with the characteristics of the modified rubber. The three stages correspond to the use of hot air with suitable parameters for drying, thereby improving the drying efficiency and further ensuring the quality of the modified rubber after drying. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This is a schematic diagram of the hot air convection drying principle of the present invention;

[0077] Figure 2 This is a schematic diagram of the overall structure of the hot air convection dehydration device of the present invention;

[0078] Figure 3 This is a front cross-sectional view of the hot air convection box of the lower air inlet drying zone of the present invention;

[0079] Figure 4 This is a front cross-sectional view of the hot air convection box in the upper air inlet drying zone of the present invention;

[0080] In the figure:

[0081] 1—Hot air convection dehydration device;

[0082] 11—mesh conveyor belt, 12—damp outlet, 13—air supply outlet, 14—heater, 15—circulating air

[0083] Machine, 16—air balancing plate. DETAILED DESCRIPTION

[0084] In order to make the technical means, creative features and objectives achieved by the present invention easy to understand, the technical solution of the present invention is further explained below in combination with one embodiment and a specific implementation method of a segmented modified rubber mesh belt hot air drying process given by the present invention.

[0085] like Figure 1-4 As shown, the specific embodiments given for the present invention are as follows:

[0086] The equipment used in the embodiment of the present invention is a hot air convection dehydration device 1, which includes a conveyor belt with mesh openings and a plurality of hot air convection boxes; the conveyor belt conveys rubber particles through the hot air convection boxes in sequence. The hot air convection box includes an upper air inlet drying zone and a lower air inlet drying zone, and the two drying zones are arranged alternately. The hot air passing through the upper air inlet drying zone and the lower air inlet drying zone passes through the rubber particle layer from top to bottom and from bottom to top, respectively. The hot air convection box of the lower air inlet drying zone includes a drying zone and a replenishing air zone, the replenishing air zone is located on one side of the drying zone, and the replenishing air zone is provided with connecting ports above and below the drying zone for passing air flow; the mesh conveyor belt 11 passes through the middle of the drying zone. A dehumidification port 12 is provided above the drying zone of the box, a replenishing air port 13 is provided above the replenishing air zone, a heater 14 is provided below the air port of the replenishing air zone, a circulating fan 15 is provided below the heater 14, and an air balancing plate 16 is also provided below the mesh conveyor belt 11 in the drying zone. The hot air convection box in the upper air inlet drying zone has an air supply port 13 and a moisture exhaust port 12 in opposite vertical positions to those in the lower air inlet drying zone. The heater 14, the circulating fan 15 and the wind direction in the air supply zone are opposite. The air equalizing plate 16 in the upper air inlet drying zone is installed above the mesh conveyor belt 11.

[0087] The following examples are for drying in a single section, and the following table shows the known material parameters:

[0088] Table 1 Known material parameters

[0089]

[0090] The required heating hot air parameters are as follows:

[0091] Table 2 Hot air parameters

[0092] Air temperature / T Net surface wind speed / V Wind area / S Hot air density / ρ 110℃ 0.6m / s <![CDATA[76m 2 ]]> <![CDATA[0.92kg / m 3 ]]>

[0093] The temperature changes of the three types of colloidal particles in the material from the feed port to the discharge port are as follows:

[0094] Table 3 Temperature changes of the pellet components from the feed port to the discharge port

[0095]

[0096] The hot air gas in different areas of the mesh belt hot air drying equipment includes 7 states; state 1 is the gas heated by the heater; state 2 is the gas transported by the circulating fan; state 3 is the gas after heat exchange with the rubber material; state 4 is the exhaust gas discharged from the dehumidification port; state 5 is the gas remaining after the exhaust gas is discharged from the dehumidification port; state 6 is the fresh air entering from the air supply port; state 7 is the gas after the fresh air in state 6 is mixed with the gas in state 5; the gas in state 7 becomes the gas in state 1 after passing through the equipment heater; the gas in the 7 states is described by the following parameters, including:

[0097] Q n : Indicates the mass flow rate of dry air in wet air under state n, unit: kg g / h;

[0098] T n : Indicates the Celsius temperature of moist air in state n, unit: ℃;

[0099] d n : Indicates the absolute moisture content of wet air under state n, that is, the mass of steam in 1 kg of dry air, unit: kg / kg g ;

[0100] H n : represents the enthalpy value of air in state n, unit: kJ / kg; Assumption: during the whole cycle, the hot air only exchanges energy with materials, fresh air and exhaust gas, and does not exchange energy with the surrounding environment or substances, and the system is in a sealed state, so there will be no gas loss. According to the law of conservation of mass, then:

[0101]

[0102] The mass conservation of steam in moist air is:

[0103]

[0104] Assume that the amount of water transferred from the material to the hot air is G s , combined with formula (2):

[0105]

[0106] Assuming that the heat exchange between the heater and the hot air is q1, and the heat exchange between the material and the hot air is q2, according to the law of conservation of energy, we have:

[0107]

[0108] Based on this, it can be obtained that in state 5, state 6 and state 7, the relationship between d and H of the gas is as follows:

[0109]

[0110] From formula (1), we can get:

[0111]

[0112] We can get:

[0113]

[0114] The air temperature in the processing environment is 25°C, the relative humidity is 70%, and the pressure is P = 101325Pa. According to the law of conservation of mass, the required feed flow rate and the amount of water evaporated from the material can be calculated:

[0115]

[0116] Where: x is the material feed flow rate corresponding to the rated production capacity;

[0117] W 1 is the moisture content of the feed material;

[0118] G is the material discharge flow rate;

[0119] W 2 is the moisture content of the material output;

[0120] Find the absolute humidity content d in fresh air 6 :

[0121]

[0122] Where: P W It is the partial pressure of vapor in air at 25°C and 70% relative humidity;

[0123] Φ is the relative humidity of the ambient air, which is 70% here;

[0124] P S is the saturated water vapor pressure of air at 25°C;

[0125] According to the air enthalpy formula, the air enthalpy values ​​at state 4 and state 6 can be calculated:

[0126]

[0127] Through the detection formula: T 4 90℃;d 4 is 0.1kg / kgg; the gas parameters of state 3 and state 5 are consistent with the gas parameters of state 4, thus:

[0128] H 3 =H 5 =H 4 =357.5 (kJ / kg)(11),

[0129] Calculate the hot air parameters, hot air circulation air volume and exhaust air volume in other states. Hot air parameter Q in state 2 2 :

[0130] Q 2 =S·V=45.6(m 3 / s)=151027(kg / h)(12),

[0131] According to formula (1), we can get:

[0132] Q 3 =Q 7 =Q 1 =Q 2 =151027(kg / h)(13),

[0133] The hot air parameters at state 7 can be obtained from formula (7):

[0134]

[0135] According to formula (2) combined with the enthalpy calculation formula, the hot air parameters in state 2 can be obtained:

[0136]

[0137] Since the hot air is in state 1 and state 2, neither T nor d has changed, so H 1 =H 2 Combining equations (13), (14), (15) and (4), the heater power q required to achieve system drying can be obtained: 1 :

[0138] q 1 =Q 1 (H 2 -H 7 )=1318.5(kW·h)(16),

[0139] In engineering design, the design power can be taken as:

[0140] q 1 '=1.2×q 1 =1582.2(kW·h)(17),

[0141] Calculate the heat q absorbed by the rubber particles from the hot air 2 :

[0142]

[0143] Where: G g is the mass of dry rubber particles;

[0144] C g is the specific heat of dry rubber particles, which is 2.1 kJ / kg℃;

[0145] C g is the specific heat of water, take 4.2 kJ / kg℃;

[0146] C q is the specific heat of water vapor, taken as 1.53 kJ / kg℃;

[0147] R s is the latent heat of water vaporization, taken as 2257 kJ / kg;

[0148] ΔT is the temperature rise difference between the three changing states;

[0149] q c1 ,q c2 ,q c3 They are the heat exchange corresponding to the three changes of evaporation of water in the rubber particles; the total heat consumed in the change process from feeding to discharging of the rubber particles can be obtained:

[0150] q 2 =q c =3616188.4(kJ)=1004.5(kW·h) (19),

[0151] Considering state 4, that is, the exhaust gas flow rate, combining equations (3), (8) and (9) we can get the exhaust gas flow rate (the density of hot air at 90°C under normal pressure is 0.97 g / m3):

[0152]

[0153] The heat in the exhaust gas is mainly composed of the heat energy carried by the dry hot air and the heat energy taken away by the steam, that is, from formula (18):

[0154]

[0155] Where: ΔT 41 is the temperature change value of the heat energy carried by the dry wind, which is 65;

[0156] ΔT 42 is the temperature change value of the heat energy carried by steam, which is taken as 20;

[0157] Considering the heat ratio in the exhaust gas, the above formula can be obtained:

[0158]

[0159] That is, the total heat carried away in the exhaust gas is about 1400kWh, mainly in steam, accounting for 76.9%. In actual engineering, in order to reduce energy consumption, it is necessary to recycle the heat in the exhaust gas, especially the heat carried by water vapor. After the state 4 exhaust gas is recycled, it can also be used for heat exchange with the heater. The calculated state 4 exhaust gas heat is combined with the original heater power required to recalculate the heater power required, further reducing energy consumption.

[0160] When the above method is applied to the sectional drying process, the whole process is divided into a heating section, a constant rate drying section and a decreasing rate drying section; the heating section is the stage where the material temperature rises from 70°C to 100°C; the constant rate drying section is the stage where the material temperature is maintained at 100°C; and the decreasing rate drying section is the stage where the material temperature decreases from 100°C to 70°C. The moisture content of the material in the heating section is W 1 Gradually decrease, the moisture content does not exceed 10%; the moisture content of the material in the constant speed drying stage gradually decreases from the discharge moisture content of the heating stage to about 10%; the moisture content of the material in the decreasing speed drying stage gradually decreases from about 10% to the discharge moisture content W 2 End. In the heating section, the hot air temperature is maintained at 130℃~140℃; the relative humidity of the hot air in state 3 is maintained at 80%~90%; in the constant-speed drying section, the hot air temperature is maintained at 120℃~130℃; the relative humidity of the hot air in state 3 is maintained at 60%~80%; in the speed-decreasing drying section, the hot air temperature is gradually reduced from 110℃~120℃ to 80℃; the relative humidity of the hot air in state 3 is gradually reduced from 60%~80% to below 10%. According to the calculated required heater power, the heaters in each section are individually regulated, which improves the drying efficiency and further ensures the quality of the modified rubber after drying.

[0161] The specific effects of traditional tunnel hot air drying and the segmented mesh belt hot air drying described in the present invention are compared as shown in the following table:

[0162]

[0163] It can be seen from the above table that the quality of the rubber dried using the present invention is significantly improved.

[0164] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A sectional modified rubber mesh belt hot air drying process, characterized in that: The following steps are involved: S1, the net belt hot air drying equipment is divided into a temperature rising section, a constant speed drying section and a speed decreasing drying section; S2, according to the parameters of the material to be dried, determine the corresponding material drying temperatures in the heating section, the constant speed drying section and the falling speed drying section, and then determine the corresponding hot air temperature and hot air humidity required to be provided according to the material drying temperature in each section; S3, detect the air temperature and humidity in the production environment; S4, according to the hot air temperature and hot air humidity required in each section, combined with the air temperature and air humidity in the production environment, calculate the power value required by the heater used in each section of the net belt hot air drying equipment, and adjust the power to heat the hot air; S5, the material to be dried enters from the feeding end of the mesh belt hot air drying equipment, passes through the heating section, the constant speed drying section and the speed decreasing drying section in sequence, and then is discharged from the discharging end after drying is completed.

2. A sectional modified rubber mesh belt hot air drying process as claimed in claim 1, characterized in that: The parameters of the material to be dried include the incoming moisture content W1, the incoming temperature, the outgoing moisture content W2, the outgoing temperature and the outgoing flow rate G; the required feed flow rate can be calculated by the following formula:

3. A sectional modified rubber mesh belt hot air drying process as claimed in claim 2, characterized in that: The hot air gas in different areas of the mesh belt hot air drying equipment includes 7 states; state 1 is the gas heated by the heater; state 2 is the gas transported by the circulating fan; state 3 is the gas after heat exchange with the rubber material; state 4 is the exhaust gas discharged from the dehumidification port; state 5 is the gas remaining after the exhaust gas is discharged from the dehumidification port; state 6 is the fresh air entering from the air supply port; state 7 is the gas after the fresh air in state 6 is mixed with the gas in state 5; the gas in state 7 becomes the gas in state 1 after passing through the equipment heater; the gas in the 7 states is described by the following parameters, including: Q n : Indicates the mass flow rate of dry air in wet air under state n, unit: kg g / h; T n : Indicates the Celsius temperature of moist air in state n, unit: ℃; d n : Indicates the absolute moisture content of wet air under n conditions, that is, the mass of steam in 1 kg of dry air, unit: kg / kg g ; H n : represents the thermal enthalpy of air in state n, unit: kJ / kg; then: The mass conservation of steam in moist air is: Assume that the amount of water transferred from the material to the hot air is G s , combined with formula (2): Assuming that the heat exchange between the heater and the hot air is q1, and the heat exchange between the material and the hot air is q2, according to the law of conservation of energy, we have: Based on this, it can be obtained that in state 5, state 6 and state 7, the relationship between d and H of the gas is as follows: From formula (1), we can get: We can get:

4. A sectional modified rubber mesh belt hot air drying process as claimed in claim 3, characterized in that: The detection instruments are used to detect the Celsius temperature T4 and the absolute moisture content d4 of the humid air discharged from the exhaust port; the relative humidity of the production environment air is recorded as Φ, and the partial pressure P of the steam in the air at this time is calculated by the detected production environment air temperature and relative humidity. W And the saturated water vapor pressure of air P S ; According to the parameters of the material to be dried, the hot air parameters during hot air flow pellet drying include the air flow temperature T, the screen wind speed V, the air flow area S and the hot air density ρ ; x is the material feed flow rate corresponding to the rated production capacity; W1 is the material feed moisture content; G is the material discharge flow rate; W2 is the material discharge moisture content. According to the law of conservation of mass, the required feed flow rate and the amount of water evaporated from the material can be calculated: Calculate the absolute humidity content d6 in the production environment air: According to the air enthalpy formula, the air enthalpy values ​​at state 4 and state 6 can be calculated: The gas parameters of state 3 and state 5 are consistent with those of state 4, thus: H3=H5=H4 (11), According to the determined hot air parameters, the hot air Q2 in state 2 can be obtained: Q2=S·V (12), According to formula (1), we can get: Q3=Q7=Q1=Q2 (13), From formula (7), we can get the hot air at state 7: According to formula (2) combined with the thermal enthalpy calculation formula, the hot air in state 2 can be obtained: Since T and d do not change between the hot air state 1 and the hot air state 2, H1 = H2. Combining equations (13), (14), (15) and (4), the calculated heater power q1 required to achieve system drying can be obtained: q1=Q1(H2-H7) (16), Taking heat loss into consideration, the design power can be: q1'=1.2×q1 (17).

5. A sectional modified rubber mesh belt hot air drying process as claimed in claim 4, characterized in that: The temperature change of the material from the feed port to the discharge port is divided into three components: A dry rubber particles, B discharge water, and C evaporation water of rubber particles. The evaporation water of rubber particles is divided into three change processes: C1 material feed water is heated to 100℃, C2 material water vaporizes at 100℃, and C3 vaporizes 100℃ water vapor temperature to T3 water vapor; then: In formula (18): G g is the mass of dry rubber particles; C g is the specific heat of dry rubber particles, which is 2.1 kJ / kg℃; C s is the specific heat of water, take 4.2 kJ / kg℃; C q is the specific heat of water vapor, taken as 1.53 kJ / kg℃; R s is the latent heat of water vaporization, taken as 2257 kJ / kg; ΔT is the temperature rise difference between the three changing states; q c1 ,q c2 ,q c3 They are the heat exchange corresponding to the three changing processes of evaporation of water in the colloid particles; The total heat consumed by the particles from feeding to discharging can be obtained: q2=q c (19), Combining equations (3), (8) and (9), we can get the exhaust gas flow rate in state 4: The heat in the exhaust gas in state 4 is mainly composed of the heat energy carried by the dry hot air and the heat energy taken away by the steam, that is, from formula (18): In formula (21): ΔT 41 is the temperature change value of the heat energy carried by the dry wind, ΔT 42 It is the temperature change value of steam carrying heat energy.

6. A sectional modified rubber mesh belt hot air drying process as claimed in claim 1, characterized in that: Before the drying process, the modified rubber material is first preheated to 70°C; the temperature rise section is the stage where the material temperature rises from 70°C to 100°C; the constant rate drying section is the stage where the material temperature is maintained at 100°C; the speed reduction drying section is the stage where the material temperature decreases from 100°C to 70°C. The moisture content of the material in the temperature rise section gradually decreases from W1, and the moisture content decreases by no more than 10%; the moisture content of the material in the constant rate drying section gradually decreases from the discharge moisture content of the temperature rise section to about 10%; the moisture content of the material in the speed reduction drying section gradually decreases from about 10% to the discharge moisture content W2.

7. A sectional modified rubber mesh belt hot air drying process as claimed in claim 6, characterized in that: The hot air temperature is maintained at 130°C to 140°C in the heating section; the relative humidity of the hot air in state 3 is maintained at 80% to 90%; the hot air temperature is maintained at 120°C to 130°C in the constant-speed drying section; the relative humidity of the hot air in state 3 is maintained at 60% to 80%; the hot air temperature in the speed-decreasing drying section is gradually reduced from 110°C to 120°C to 80°C; the relative humidity of the hot air in state 3 is gradually reduced from 60% to 80% to below 10%.

8. A sectional modified rubber mesh belt hot air drying process as claimed in claim 5, characterized in that: The state 4 exhaust gas is recovered and used for heat exchange with the heater. The calculated state 4 exhaust gas heat is combined with the original heater required power to recalculate the heater required power, further reducing energy consumption.

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