Sectional modified rubber mesh belt hot air drying process

Abstract

The present application relates to a kind of section type modified rubber mesh belt hot air drying process, comprising the following steps: S1, mesh belt hot air drying equipment is divided into temperature rising section, constant speed drying section and falling speed drying section, and the material to be dried is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment feeding end, and is sequentially dried after entering from equipment

Description

TECHNICAL FIELD

[0001] The present application relates to the field of natural rubber drying processing, in particular to a sectional modified rubber mesh belt hot air drying process. BACKGROUND

[0002] Natural rubber is an important strategic base material for national security and people's livelihood, and is called the four major industrial raw materials together with steel, oil and coal. It has the dual attributes of agricultural products and industrial products, and is a basic industry related to national economy and people's livelihood, and is also an important strategic material. Because it has good mechanical strength, low heat generation after deformation for many times, and good flex resistance, good electrical insulation, large elasticity, high modulus of elasticity, 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 rubber belts, and occupies an irreplaceable position in national defense, aerospace, rail transportation, and marine equipment. With the continuous progress of science and technology, scientists have found that modified rubber has significantly improved wear resistance, tensile strength, flex resistance, and aging resistance compared to natural rubber. For example, the flex resistance of the tire side rubber can be improved from 100,000 times to more than 500,000 times. Therefore, the modification of rubber will be the main research focus of the rubber industry in the future. Currently, the modified rubber in the industry is mainly achieved by adding modified substances to natural rubber to reinforce the rubber, and the reinforced rubber often needs to be dried by a mesh belt hot air drying system.

[0003] The heat transfer and dehydration mechanism of the mesh belt hot air drying system: the circulating hot air transfers heat to the rubber particles as it passes through the material layer. The rubber particles absorb heat and their surface liquid water vaporizes into the hot air. As the surface water of the rubber particles continues to vaporize, the water content of the surface layer decreases, forming a water content gradient with the internal structure. Through continuous heat absorption, surface water vaporization, and internal water migration, the water in the material is finally transferred to the hot air, achieving material drying.

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

[0005] However, the currently adopted net belt type hot air drying equipment is integrally controlled, and there is no partition drying for the characteristics of modified rubber. The equipment has the disadvantages of high energy consumption, serious heat loss, low drying efficiency and the like, and the quality of the dried modified rubber is often difficult to guarantee. Therefore, the existing technology restricts the development of modified rubber, and many researchers and scholars have specially studied the net belt type hot air drying equipment. SUMMARY

[0006] To solve the above problems, the present application provides a sectional modified rubber net 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 needs of the drying characteristics and yield of the modified rubber, improve the drying efficiency of the modified rubber, reduce the drying energy consumption, and also ensure the quality of the dried modified rubber. Specifically, the purpose of the present application is achieved as follows:

[0007] A sectional modified rubber net belt hot air drying process, comprising 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 reducing drying section;

[0009] S2, according to the material parameters to be dried, the corresponding material drying temperature in the temperature rising section, the constant speed drying section and the speed reducing drying section is determined, and then the required hot air temperature and hot air humidity provided in each section are determined according to the material drying temperature in each section;

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

[0011] S4, according to the required hot air temperature and hot air humidity provided in each section, combining the air temperature and air humidity in the production environment, calculating the required power value of the heater used in each section of the net belt hot air drying equipment, and adjusting the power to heat the hot air;

[0012] S5, after the material to be dried enters the feeding end of the net belt hot air drying equipment, it passes through the temperature rising section, the constant speed drying section and the speed reducing drying section in turn, and is dried and discharged from the discharging end.

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

[0014]

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

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

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

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

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

[0020]

[0021] The steam mass in the wet air is conserved, and has:

[0022]

[0023] Let the amount of water transferred from the material to the hot air be G s , combined with equation (2), there is:

[0024]

[0025] Let the heat exchange amount between the heater and the hot air be q1, and the heat exchange amount between the material and the hot air be q2, according to the law of conservation of energy, there is:

[0026]

[0027] Accordingly, under states 5, 6 and 7, the d and H of the gas exist the following relationships:

[0028]

[0029] From equation (1), we have:

[0030]

[0031] Available:

[0032]

[0033] Further, the Celsius temperature T4 of the wet air of the state 4 exhaust gas discharged from the moisture discharge port and the absolute humidity d4 of the wet air are detected by the detection instrument respectively; the relative humidity of the production environment air is denoted as Φ, and the partial pressure P of the steam in the air at this time is calculated according to the detected air temperature and the relative humidity of the air W and the saturated water vapor pressure P S of the air; the hot air parameters including the hot air temperature T, the mesh surface air speed V, the hot air area S and the hot air density ρ when the hot air penetrates the rubber particles are determined according to the parameters of the material to be dried; x is the material feeding flow corresponding to the rated production capacity; W1 is the water content of the material feeding; G is the material discharging flow; W2 is the water content of the material discharging, and the required feeding flow and the evaporated water in the material can be calculated according to the mass conservation:

[0034]

[0035] The absolute humidity d6 of the air in the production environment is calculated:

[0036]

[0037] The air enthalpy values of the air at the state 4 and the state 6 can be calculated according to the air enthalpy formula:

[0038]

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

[0040] H3 = H5 = H4 (11),

[0041] According to the determined hot air parameters, the hot air Q2 at the state 2 can be obtained:

[0042] Q2 = S·V (12),

[0043] According to the formula (1), we have:

[0044] Q3 = Q7 = Q1 = Q2 (13),

[0045] The hot air at the state 7 can be obtained from the formula (7):

[0046]

[0047] The hot air at the state 2 can be obtained according to the formula (2) combined with the enthalpy calculation formula:

[0048]

[0049] Since the hot air does not change T and d between state 1 and state 2, H1=H2, combined with formula (13), (14), (15) and formula (4), the required heater calculation power q1 for system drying can be obtained:

[0050] q1=Q1(H2-H7)(16),

[0051] Considering heat loss, the design power in specific use can be:

[0052] q1' = 1.2 x q1(17).

[0053] Further, the temperature change of the material from the feed inlet to the discharge outlet is divided into three components: A dry rubber particles, B discharge moisture, and C rubber particle evaporation moisture, wherein the rubber particle evaporation moisture is divided into three change processes: C1 moisture in the material to moisture in the material heated to 100℃, C2 moisture in the material heated to 100℃ to vaporization, and C3 water vapor after vaporization to T3 water vapor; 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, taken as 2.1 kJ / kg℃;

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

[0059] C q is 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 of the three change states;

[0062] q c1 , q c2 , and q c3 are the heat exchange amounts corresponding to the three change processes of the evaporation moisture in the rubber particles, respectively;

[0063] Therefore, the total heat required for the change process of the rubber particles from the feed to the discharge can be obtained as:

[0064] q 2 = q c (19),

[0065] Combining formula (3), formula (8) and formula (9), the state 4 exhaust flow can be obtained:

[0066]

[0067] In the state 4 exhaust, the heat mainly consists of the heat energy carried by the dry hot air and the heat energy taken away by the steam, i.e., obtained from formula (18):

[0068]

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

[0070] Further, the modified rubber material is first preheated to 70 DEG C before the drying process; the temperature rising section is the stage of rising the material temperature from 70 DEG C to 100 DEG C; the constant speed drying section is the stage of maintaining the material temperature at 100 DEG C; and the temperature decreasing drying section is the stage of decreasing the material temperature from 100 DEG C to 70 DEG C. The moisture content of the material in the temperature rising section is gradually decreased from W1, and the moisture content is decreased by no more than 10%; the moisture content of the material in the constant speed drying section is gradually decreased to about 10% from the moisture content of the material out of the temperature rising section; and the moisture content of the material in the temperature decreasing drying section is gradually decreased to W2 from about 10% to end.

[0071] Further, the hot air temperature in the temperature rising section is maintained at 130 DEG C to 140 DEG C; and the relative humidity of the state 3 hot air is maintained at 80% to 90%, so that the material is rapidly heated in the high temperature and high humidity environment, and the moisture gradient between the surface and the internal organization of the material is small; the hot air temperature in the constant speed drying section is maintained at 120 DEG C to 130 DEG C; and the relative humidity of the state 3 hot air is maintained at 60% to 80%. The hot air temperature mainly provides heat for the material dehydration, but cannot make the temperature of the material exceed 100 DEG C; the hot air temperature in the temperature decreasing drying section is gradually decreased from 110 DEG C to 120 DEG C to 80 DEG C; the relative humidity of the state 3 hot air is gradually decreased from 60% to 80% to below 10%; and in this environment state, the material temperature is gradually decreased from 100 DEG C to 70 DEG C, and the hot air can remove the moisture from the material.

[0072] Further, the state 4 exhaust is recovered to exchange heat with the heater, the required power of the heater is recalculated by using the calculated state 4 exhaust heat and the originally required power of the heater, and the energy consumption is further reduced.

[0073] The present application has the following beneficial effects:

[0074] (I) This invention can adjust the feed flow rate of the upstream 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, hot air heat supply, drying time, and 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℃, which is lower than the traditional 120℃~130℃, increases the P0 value of the rubber particles by more than 20%, increases the tensile strength by more than 10%, increases the Mooney viscosity by more than 10%, and reduces the hot air energy consumption by more than 15%.

[0075] (II) This invention calculates and monitors the parameters of hot air under various conditions during the drying of modified rubber in real time. Combined with the characteristics of modified rubber, the drying stage of modified rubber is divided into a heating stage, a constant speed drying stage, and a falling speed drying stage. The three stages are respectively dried with hot air of suitable parameters, which improves the drying efficiency and further ensures the quality of the modified rubber after drying. Attached Figure Description

[0076] Fig. 1 This is a schematic diagram illustrating the hot air convection drying principle described in this invention.

[0077] Fig. 2 This is a schematic diagram of the overall structure of the hot air convection dehydration device described in this invention;

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

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

[0080] In the picture:

[0081] 1—Hot air convection dehydration device;

[0082] 11—Mesh conveyor belt, 12—Dampness outlet, 13—Make-up air inlet, 14—Heater, 15—Circulating air

[0083] Machine, 16—air distribution plate. Detailed Implementation

[0084] To make the technical means, inventive features, and objectives of this invention easier to understand, the technical solution of this invention will be further explained below with reference to one embodiment of a segmented modified rubber mesh belt hot air drying process and specific implementation methods.

[0085] like Figs. 1-4 As shown, specific embodiments of the present invention are as follows:

[0086] The device used in the embodiment of the application is a hot air convection dewatering device 1, which comprises a meshed conveying belt and a plurality of hot air convection boxes. The conveying belt conveys rubber particles through the hot air convection boxes in sequence. The hot air convection boxes comprise upper air inlet drying zones and lower air inlet drying zones, which are arranged alternately. The hot air passing through the upper air inlet drying zones and the lower air inlet drying zones 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 comprises a drying zone and a make-up air zone. The make-up air zone is located on one side of the drying zone, and the make-up air zone and the drying zone are provided with communication ports above and below the drying zone for passing air. The meshed conveying belt 11 passes through the middle of the drying zone. A moisture discharge port 12 is arranged above the drying zone, a make-up air port 13 is arranged above the make-up air zone, a heater 14 is arranged below the make-up air port of the make-up air zone, a circulating fan 15 is arranged below the heater 14, and an air uniformizing plate 16 is arranged below the meshed conveying belt 11 of the drying zone. The make-up air port 13 and the moisture discharge port 12 of the hot air convection box of the upper air inlet drying zone are opposite in position, the heater 14 and the circulating fan 15 of the make-up air zone are opposite in direction, and the air uniformizing plate 16 of the upper air inlet drying zone is arranged above the meshed conveying belt 11.

[0087] The following examples are single-zone drying, and the following table shows the known material parameters:

[0088] Table 1 Known material parameters

[0089]

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

[0091] Table 2 Hot air parameters

[0092] Through-air temperature / T Web surface wind speed / V Through-air area / S Hot air density / p 110℃ 0.6 m / s 76m 2 ]] 0.92 kg / m 3 ]]

[0093] The temperature changes of the three rubber particle components in the material from the feed inlet to the discharge outlet are as follows:

[0094] Table 3 Temperature changes of rubber particle components from the feed inlet to the discharge outlet

[0095]

[0096] The hot air gas in different regions of the mesh belt hot air drying device comprises seven states; state 1 is the gas after being heated by the heater; state 2 is the gas after being conveyed by the circulating fan; state 3 is the gas after heat exchange with the rubber material; state 4 is the exhaust gas discharged at the moisture discharge port; state 5 is the gas remaining after the exhaust gas is discharged at the moisture discharge port; state 6 is fresh air entering from the make-up air port; state 7 is the gas obtained by mixing the fresh air of state 6 and the gas of state 5; the gas of state 7 becomes the gas of state 1 after being heated by the device heater; the gases of the seven states are described by the following parameters, which include:

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

[0098] T n : represents the Celsius temperature of the n state of the wet air, unit: ℃;

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

[0100] H n : represents the enthalpy of the n state of the air, unit: kJ / kg; it is assumed that the hot air only exchanges energy with the material, fresh air, and waste gas in the entire cycle, and does not exchange energy with the surrounding environment and the material, and the system is in a sealed state and does not occur gas loss. According to the law of conservation of mass, then:

[0101]

[0102] The steam mass conservation in the wet air is:

[0103]

[0104] Let the water amount transferred from the material to the hot air be G s , combined with equation (2), there is:

[0105]

[0106] Let the heat exchange amount between the heater and the hot air be q1, and the heat exchange amount between the material and the hot air be q2, according to the law of conservation of energy, there is:

[0107]

[0108] Accordingly, the d and H of the gas under the state 5, state 6 and state 7 exist the following relationships:

[0109]

[0110] From equation (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 P is 101325 Pa. According to the mass conservation, the required feed flow rate and the amount of water evaporated in the material can be calculated:

[0115]

[0116] In the formula, x is the material feed flow rate corresponding to the rated production capacity;

[0117] W1 is the moisture content of the material feed;

[0118] G is the material discharge flow rate;

[0119] W2 is the moisture content of the material discharge;

[0120] The absolute wet content d6 in the fresh air is calculated as follows:

[0121]

[0122] In the formula, P W is the partial pressure of steam in the air at a temperature of 25°C and a relative humidity of 70%;

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

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

[0125] According to the air enthalpy value formula, the air enthalpy values of the air at states 4 and 6 can be calculated:

[0126]

[0127] By detecting, in the formula: T4 is 90°C; d4 is 0.1 kg / kgg; the gas parameters at states 3 and 5 are consistent with those at state 4, so:

[0128] H3 = H5 = H4 = 357.5 (kJ / kg) (11),

[0129] The hot air parameters, hot air circulation air volume, and waste air volume at other states are calculated. The hot air parameter Q2 at state 2 is:

[0130] Q2 = S·V = 45.6 (m 3 / s) = 151027 (kg / h) (12),

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

[0132] Q3 = Q7 = Q1 = Q2 = 151027 (kg / h) (13),

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

[0134]

[0135] The hot air parameters at state 2 can be obtained from equation (2) combined with the enthalpy calculation formula:

[0136]

[0137] Since the hot air does not change T and d between state 1 and state 2, H1 = H2, combined with equations (13), (14), (15) and equation (4), the required heater calculation power q1 for system drying can be obtained:

[0138] q1 = Q1 (H2 - H7) = 1318.5 (kW h) (16),

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

[0140] q1' = 1.2 x q1 = 1582.2 (kW h) (17),

[0141] The heat absorbed by the granules from the hot air q2 is:

[0142]

[0143] In the formula: G g is the mass of dry granules;

[0144] C g is the specific heat of dry granules, taken as 2.1 kJ / kg°C;

[0145] C g is the specific heat of water, taken as 4.2 kJ / kg°C;

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

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

[0148] ΔT is the temperature rise difference of the three change states;

[0149] q c1 , q c2 , q c3 are the heat exchange amounts corresponding to the three change processes of the evaporated water in the granules, respectively; and the total heat consumed by the granules from the feed to the discharge can be obtained as:

[0150] q2 = q c = 3616188.4 (kJ) = 1004.5 (kW h) (19),

[0151] Considering state 4, i.e. exhaust gas flow, combined with equation (3), equation (8) and equation (9), the exhaust gas flow (hot air density at 90℃ under normal pressure takes 0.97g / m3) can be obtained:

[0152]

[0153] Wherein, 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, i.e. obtained from equation (18):

[0154]

[0155] In the formula: ΔT 41 The temperature change value of the heat energy carried by the dry air is 65;

[0156] ΔT 42 The temperature change value of the heat energy carried by the steam is 20;

[0157] Considering the proportion of the heat in the exhaust gas, the above equation can be obtained:

[0158]

[0159] That is, the total heat taken away in the exhaust gas is about 1400kWh, mainly in the steam, accounting for 76.9%, in actual engineering, in order to reduce energy consumption, the heat in the exhaust gas, especially the heat carried by the water vapor, needs to be recovered and utilized. The state 4 exhaust gas can be used for heat exchange with the heater after recovery, and the required power of the heater is recalculated by using the calculated heat of state 4 exhaust gas combined with the original required power of the heater, to further reduce energy consumption.

[0160] When applying the above method to segmented drying, the entire process is divided into a heating stage, a constant-rate drying stage, and a falling-rate drying stage. The heating stage is the phase where the material temperature rises from 70℃ to 100℃; the constant-rate drying stage maintains the material temperature at 100℃; and the falling-rate drying stage is the phase where the material temperature decreases from 100℃ to 70℃. In the heating stage, the material moisture content gradually decreases from W1, with a decrease not exceeding 10%; in the constant-rate drying stage, the material moisture content gradually decreases from the discharge moisture content of the heating stage to approximately 10%; and in the falling-rate drying stage, the material moisture content gradually decreases from approximately 10% until the discharge moisture content reaches W2. 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 deceleration drying section, the hot air temperature 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%. The heaters in each section are individually controlled according to the calculated required heater power, improving drying efficiency while further ensuring the quality of the dried modified rubber.

[0161] The following table compares the specific effects of traditional tunnel hot air drying with the segmented mesh belt hot air drying described in this invention:

[0162]

[0163] The table above clearly shows that the quality of rubber dried using this invention is significantly improved.

[0164] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A segmented modified rubber mesh belt hot air drying process, characterized in that, Includes the following steps: S1, the mesh belt hot air drying equipment is divided into a heating section, a constant speed drying section and a falling speed drying section; S2, based on the parameters of the material to be dried, determine the corresponding material drying temperature in the heating section, constant speed drying section and falling speed drying section, and then determine the corresponding hot air temperature and hot air humidity based on the material drying temperature in each section; S3 detects the air temperature and humidity in the production environment; S4. Based on the required hot air temperature and humidity in each section, combined with the air temperature and humidity in the production environment, calculate the required power value of the heater used in each section of the mesh belt hot air drying equipment, and adjust it to that power to heat the hot air. S5, the material to be dried enters from the feed end of the mesh belt hot air dryer and passes through the heating section, constant speed drying section and deceleration drying section in sequence. After drying, the material is discharged from the discharge end.

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

3. The segmented modified rubber mesh belt hot air drying process as described in claim 2, characterized in that: The hot air gas in different zones of the mesh belt hot air drying equipment includes seven 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 through the air inlet; State 7 is the gas after the fresh air of State 6 and the gas of State 5 are mixed; the gas of State 7 becomes the gas of State 1 after passing through the equipment heater. The seven states of gas are described by the following parameters, including: Q n : Represents the mass flow rate of dry air in moist air at state n, unit: kg g / h; T n : Represents the Celsius temperature of moist air in state n, in °C; d n : Represents the absolute moisture content of moist air under state n, i.e., the mass of vapor in 1 kg of dry air, unit: kg / kg g ; H n : represents the enthalpy of air in state n, in kJ / kg; then: The mass of vapor in moist air is conserved, therefore: Let G be the amount of water transferred from the material into the hot air. s Combining equation (2), we have: Let the heat exchange between the heater and the hot air be q1, and the heat exchange between the material and the hot air be q2. According to the law of conservation of energy, we have: Therefore, the following relationship exists between d and H of the gas in states 5, 6, and 7: From equation (1), we can obtain: We can obtain:

4. The segmented modified rubber mesh belt hot air drying process as described in claim 3, characterized in that: The temperature (T4) and absolute moisture content (d4) of the humid air discharged from the exhaust vent (state 4) were measured using instruments. The relative humidity of the production environment air was denoted as Φ. The partial pressure of vapor in the air at this time was calculated using the measured temperature and relative humidity. W And the saturated water vapor pressure P of the air S The hot air parameters for drying granules using hot air through-flow are determined based on the parameters of the material to be dried. These parameters include the air temperature T, the mesh surface velocity V, the airflow area S, and the hot air density ρ. x represents the material feed flow rate corresponding to the rated production capacity; W1 represents the material feed moisture content; G represents the material discharge flow rate; and W2 represents the material discharge moisture content. Based on 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 ambient air during production: The enthalpy of air in states 4 and 6 can be calculated using the formula for air enthalpy: The gas parameters in states 3 and 5 are the same as those in state 4, therefore: H3=H5=H4 (11), Based on the determined hot air parameters, the hot air Q2 under state 2 can be obtained: Q2=S·V (12), According to equation (1), we can obtain: Q3 = Q7 = Q1 = Q2 (13), From equation (7), the hot air in state 7 can be obtained: According to equation (2) and the enthalpy calculation formula, the hot air in state 2 can be obtained as follows: Since T and d do not change between states 1 and 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), Considering heat loss, the design power can be taken as follows for specific use: q1'=1.2×q1 (17).

5. The segmented modified rubber mesh belt hot air drying process as described in claim 4, characterized in that: The temperature change of the material from the inlet to the outlet is divided into three components: A. dry granules, B. outlet moisture, and C. evaporated moisture from the granules. The evaporated moisture from the granules is further divided into three processes: C1. inlet moisture heated to 100℃; C2. moisture in the material vaporizing at 100℃; and C3. vaporization followed by a change in water vapor temperature from 100℃ to T3 (water vapor temperature). Therefore: In equation (18): G g For dry granule quality; C g The specific heat of dry rubber particles is taken as 2.1 kJ / kg℃; C s The specific heat of water is taken as 4.2 kJ / kg℃; C q The specific heat of water vapor is taken as 1.53 kJ / kg℃; R s The latent heat of water vaporization is taken as 2257 kJ / kg; ΔT represents the temperature rise difference between the three changing states; q c1 q c2 q c3 These represent the heat exchange corresponding to the three processes of moisture evaporation from the colloidal particles; The total heat consumed during the process of the rubber particles changing from feed to discharge can be obtained: q2=q c (19), Combining equations (3), (8), and (9), the exhaust gas flow rate for state 4 can be obtained: Among them, the heat in the exhaust gas of state 4 mainly consists of the heat energy carried by the dry hot air and the heat energy carried away by the steam, that is, from equation (18): In equation (21): ΔT 41 ΔT represents the temperature change of the dry wind carrying heat energy. 42 This represents the temperature change value of steam carrying thermal energy.

6. The segmented modified rubber mesh belt hot air drying process as described in claim 1, characterized in that: Before the drying process, the modified rubber material is first preheated to 70°C; 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; the falling-rate drying section is the stage where the material temperature drops from 100°C to 70°C; the material moisture content gradually decreases from W1 in the heating section, and the moisture content decreases by no more than 10%; the material moisture content gradually decreases from the discharge moisture content in the constant-rate drying section to about 10%; the material moisture content gradually decreases from about 10% in the falling-rate drying section until the discharge moisture content W2 ends.

7. The segmented modified rubber mesh belt hot air drying process as described in claim 6, characterized in that: 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 deceleration drying section, the hot air temperature 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%.

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

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