Cooling regulation and control method

Abstract

The invention discloses a cooling regulation and control method, and belongs to the technical field of roasting machines. The method comprises the step of distributing cooling air in different air boxes by regulating and controlling the frequency of a cooling fan and valves of the air boxes so as to optimize the roasting section smoke hood pressure and the cooling section tail end smoke hood temperature of the roasting machine. According to the invention, full-automatic intelligent cooling control of the roasting machine is realized, and intelligent automatic control for replacing manual operation is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of roasting machines, and in particular relates to a cooling control method. Background Art

[0002] The cooling section of the belt roaster has multiple air boxes distributed at the end of the roaster, whose main function is to cool the pellets and provide circulating air volume.

[0003] If the cooling air volume of the bellows is too large, the flue gas temperature after cooling at the end of the belt roaster will be too low, and the flue gas after cooling at the end of the belt roaster will be drawn away by the fan of the blast drying section to dry the moisture of the raw balls. If the flue gas temperature is too low, the drying effect of the raw balls will deteriorate, which will cause the preheating section or roasting section of the belt roaster to require more heat to dry the raw balls. This not only increases energy consumption, but also causes the moisture on the surface of the raw balls to evaporate and enter the high-temperature preheating or roasting section of the belt roaster above 800°C, increasing the probability of pellet bursting, resulting in fluctuations in the quality of the finished balls. If the air volume of the bellows is too low, the temperature of the finished balls may be too high, damaging equipment such as transportation belts.

[0004] In view of the above situation, the commonly used control methods are as follows:

[0005] In manual mode, the operator sets the cooling fan frequency and monitors the belt roaster's hood pressure and cooling end hood temperature. When the hood pressure (negative pressure) is excessive or positive pressure is present, the cooling fan frequency is adjusted. Similarly, when the cooling end hood temperature is too high or too low, the cooling fan frequency is adjusted. The bellows valve is typically fully open and rarely adjusted. The disadvantages of this manual control mode are: high labor intensity, different control results may vary depending on the operator, slow response, and significant variability and randomness. Summary of the Invention

[0006] In order to solve the technical problem of manually controlling the hood pressure of a belt roaster and the hood temperature at the end of the cooling section in the prior art, a cooling control method is provided.

[0007] The present invention provides a cooling control method applicable to a roasting machine, comprising the following steps:

[0008] The cooling air volume is distributed among different air boxes by regulating the frequency of the cooling fan and the valve of the air box, so as to optimize the hood pressure of the roasting section and the hood temperature at the end of the cooling section of the roasting machine;

[0009] The frequency of the cooling fan and the valve of the bellows are both automatically regulated, and the state of the valve of the bellows includes a fully open state and a partially open state;

[0010] The roaster includes a drying section, a preheating section, a roasting section, a soaking section, and a cooling section. The cooling section includes a first cooling section and a second cooling section. The air in the first cooling section penetrates the material layer of the roaster and enters the soaking section, the roasting section, and the preheating section, and is then extracted by the main exhaust fan and the reheating fan. The air in the second cooling section cools the pellets in the roaster and then enters the drying section through the drying fan to dry the pellets.

[0011] The cooling fan and the valve of the wind box serve as main components of a plurality of wind boxes, and the plurality of wind boxes are arranged in the cooling section of the roaster and distributed at the end of the roaster.

[0012] In some embodiments, when the absolute value of the speed fluctuation value of the roaster is greater than the roaster speed fluctuation threshold, the frequency of the cooling fan is increased by a first frequency change value based on the frequency setting value;

[0013] The speed fluctuation value of the roasting machine is the difference between the current speed setting value of the roasting machine and the previous speed setting value;

[0014] The first frequency change value is a value obtained by multiplying the speed fluctuation value of the roasting machine by a first coefficient.

[0015] In some embodiments, when the absolute value of the frequency fluctuation value of the main exhaust fan is greater than the main exhaust fan frequency fluctuation threshold, the frequency of the cooling fan is increased by a second frequency change value based on the frequency setting value;

[0016] The frequency fluctuation value of the main exhaust fan is the difference between the current frequency setting value of the main exhaust fan and the previous frequency setting value;

[0017] The second frequency change value is a value obtained by multiplying the frequency fluctuation value of the main exhaust fan by a second coefficient.

[0018] In some embodiments, when the absolute value of the frequency fluctuation value of the regenerative fan is greater than the regenerative fan frequency fluctuation threshold, the frequency of the cooling fan is increased by a third frequency change value on the basis of the frequency setting value;

[0019] The frequency fluctuation value of the reheating fan is the difference between the current frequency setting value of the reheating fan and the previous frequency setting value;

[0020] The third frequency change value is a value obtained by multiplying the frequency fluctuation value of the heat recovery fan by a third coefficient.

[0021] In some embodiments, when the valve openings of the air boxes in the first cooling section and the second cooling section cause the temperature of the end hood of the roaster to be lower than a first temperature threshold or higher than a second temperature threshold, the frequency of the cooling fan is increased by a fourth frequency variation value based on the frequency setting value;

[0022] The fourth frequency change value is determined based on the temperature difference of the terminal smoke hood and the dead zone ratio.

[0023] In certain embodiments, the change in the smoke hood pressure of the roasting section is used as one of the influencing factors for regulating the frequency of the cooling fan.

[0024] In some embodiments, the frequency fluctuation value of the cooling fan is determined, and combined with the previous frequency setting value of the cooling fan, an initial setting value of the frequency output of the cooling fan is constructed, and a limit function of the value range is set around the initial setting value of the frequency output of the cooling fan to determine the final setting value of the frequency output of the cooling fan.

[0025] In some embodiments, the first coefficient has a value range of 0-10.

[0026] In some embodiments, the second coefficient has a value range of 0-3.

[0027] In some embodiments, the third coefficient has a value range of 0-3.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention distributes the cooling air volume to different wind boxes by automatically regulating the frequency of the cooling fan and the valve of the wind box, so as to optimize the smoke hood pressure of the roasting section and the smoke hood temperature at the end of the cooling section of the roasting machine, thereby realizing fully automatic intelligent cooling control and realizing intelligent automatic control that replaces manual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of hot air circulation of a belt roasting machine provided in one embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of factors affecting target pressure and temperature provided in one embodiment of the present invention;

[0032] Figure 3 Schematic diagram of the intelligent cooling control principle provided in one embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the intelligent cooling control process provided in one embodiment of the present invention;

[0034] Figure 5It is a schematic diagram of a cooling temperature control process provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0036] In one embodiment, a cooling control method is provided, which is applicable to a roaster, especially a belt roaster, and is used for intelligent cooling of pellets in the belt roaster.

[0037] like Figure 1 As shown in Figure 5, the belt roaster includes a drying section, an exhaust section, a preheating section, a roasting section, a soaking section, and a cooling section. The cooling section includes a first cooling section and a second cooling section. The air volume distribution between the first and second cooling sections is determined by the number of bellows. Typically, the first cooling section is equipped with five bellows, and the second cooling section is equipped with two bellows. When the valves on the bellows are fully open, the air volume ratio is 5:2. Typically, two regulating valves are installed in the bellows on the first cooling section, and one regulating valve is installed in the bellows on the second cooling section. The air in the first cooling section penetrates the roaster's material layer and enters the soaking section, roasting section, and preheating section. It is then extracted by the main exhaust fan and the reheating fan. Therefore, changes in the air volume of the main exhaust fan and the reheating fan will affect the cooling effect of the pellets. After cooling the pellets in the roaster, the air in the second cooling section passes through the drying fan and enters the drying section for deep drying. At the same time, changes in the roaster speed or material layer thickness will also directly affect the cooling effect of the pellets.

[0038] The cooling control method includes the following steps: distributing the cooling air volume to different wind boxes by regulating the frequency of the cooling fan and the valve of the wind box to optimize the smoke hood pressure of the roasting section and the smoke hood temperature at the end of the cooling section of the roasting machine, thereby achieving dual-objective optimization control of the smoke hood pressure of the roasting section and the smoke hood temperature at the end of the cooling section; the end smoke hood refers to the smoke hood corresponding to the last wind box of the roasting machine; dual-objective optimization control refers to controlling the temperature of the end smoke hood to be stable while ensuring the stability of the smoke hood pressure of the roasting section.

[0039] The frequency of the cooling fan and the valve of the bellows are both automatically controlled, and the status of the bellows valve includes a fully open state and a partially open state;

[0040] The cooling fan and the valve of the wind box are the main components of the plurality of wind boxes, and the plurality of wind boxes are arranged in the cooling section of the roaster and distributed at the end of the roaster.

[0041] This cooling control method is a multivariable dual-objective optimization control method. It extracts the impact of the roaster speed, main exhaust fan air volume and heat recovery fan air volume changes on the cooling fan as the disturbance quantity, and takes synchronous action in advance to reduce the lag of feedback control. At the same time, the bellows valve is used to redistribute the cooling air volume of the bellows to achieve a stable cooling effect, that is, to reduce the temperature fluctuation of a certain section of the smoke hood.

[0042] like Figure 2 and Figure 3 As shown in the figure, it can be seen that the factors affecting the cooling control target value are divided into two categories, one is the disturbance quantity and the other is the control quantity. By simulating the actual operation experience on site, the changes in the disturbance quantity are grasped and the control quantity is adjusted to reduce the fluctuation of the target value. When the target value fluctuates, the corresponding control quantity is adjusted to achieve the purpose of further stabilizing the target value. The detailed control process is shown in the figure. Figure 4 shown.

[0043] In some embodiments, the control of the roaster speed (or material thickness) when it fluctuates

[0044] The speed and material thickness of the roasting machine change dynamically, and small fluctuations have little effect on the cooling effect, which can be compensated by pressure feedback control and are basically not within the scope of consideration. Only when the speed of the roasting machine fluctuates greatly will it have a greater impact on the cooling effect.

[0045] When the set speed value of the roasting machine changes, the difference before and after the change is judged. When the absolute value of the difference is greater than the roasting machine speed fluctuation threshold k1 (the parameter can be modified, the default is 0.15), the output is according to the formula, otherwise, the output is 0.

[0046] When the absolute value of the roaster speed fluctuation value r1 is greater than the roaster speed fluctuation threshold k1, the frequency of the cooling fan is increased by the first frequency change value Δy1 based on the frequency setting value, as follows:

[0047] If|r1|>k1 then

[0048] Δy1=p1*r1

[0049] Else

[0050] Δy1=0

[0051] End

[0052] sp is the current speed setting value of the roaster, sp1 is the last speed setting value of the roaster; r1 is the deviation between the two settings, that is, the speed fluctuation value of the roaster. The speed fluctuation value of the roaster is the difference between the current speed setting value of the roaster and the last speed setting value: r1 = sp - sp1;

[0053] The first frequency variation value Δy1 is the value obtained by multiplying the speed fluctuation value r1 of the roasting machine by the first coefficient p1. In some embodiments, the first coefficient p1 is adjusted according to the on-site conditions and has a value range of 0-10, preferably p1=5.

[0054] In some embodiments, the current speed setting value of the roasting machine sp = 2.8 m / min, the previous speed setting value of the roasting machine sp1 = 3.0 m / min, the speed fluctuation value of the roasting machine r1 = 3.0-2.8 = 0.2, and the speed fluctuation threshold value of the roasting machine k1 = 0.15.

[0055] Δy1=5*0.15=0.75Hz, where p1=5, that is, when the roasting machine Δy1=speed changes from 2.8m / min to 3.0m / min, the frequency of the cooling fan increases by 0.75Hz. If the corresponding cooling fan frequency is 30Hz when the machine speed is 2.8m / min, then the cooling fan frequency is 30.75Hz when the machine speed is 3.0m / min. This step is the feedforward disturbance adjustment. If the adjustment is too large or too small, it will be adjusted again by feedback pressure or temperature.

[0056] If the machine speed changes from 2.8m / min to 2.9m / min or 2.7m / min, the absolute value of r1 is 0.1, which is less than k1, then Δy1=0, and the cooling fan is temporarily not adjusted.

[0057] In some embodiments, the control of the main exhaust fan frequency changes

[0058] When the event is triggered, when the set frequency value of the main exhaust fan changes, the difference before and after the change is judged. When the absolute value of the difference is greater than the exhaust fan frequency fluctuation threshold k2 (the parameter can be modified, the default is 0.5), the output is according to the formula, otherwise, the output is 0.

[0059] When the absolute value of the frequency fluctuation value r2 of the main exhaust fan is greater than the main exhaust fan frequency fluctuation threshold k2, the frequency of the cooling fan is increased by a second frequency change value Δy2 on the basis of the frequency setting value, as follows:

[0060] r2=sp-sp1

[0061] If|r2|>k2 then

[0062] Δy2=p2*r2

[0063] Else

[0064] Δy2=0

[0065] End

[0066] sp is the current frequency set value of the main extraction fan, sp1 is the previous frequency set value of the main extraction fan, and r2 is the deviation between the two settings, that is, the frequency fluctuation value r2 of the main extraction fan. The frequency fluctuation value r2 of the main extraction fan is the difference obtained by subtracting the previous frequency set value sp1 from the current frequency set value sp of the main extraction fan;

[0067] The second frequency change value Δy2 is the value obtained by multiplying the frequency fluctuation value r2 of the main extraction fan by the second coefficient p2. In some embodiments, the second coefficient p2 is adjusted according to the on-site situation, and the value range is in the interval of 0-3. Preferably, p2 = 1.

[0068] In some embodiments, if the frequency of the main extraction fan changes from 40Hz to 38Hz, then sp = 38, sp1 = 40, r2 = 38 - 40 = -2, and the absolute value |r2| of r2 = 2 > k2, (k2 = 0.5). Then the frequency change amount Δy2 of the cooling fan = p2 * r2 = -2, p2 = 1. That is, when the frequency of the main extraction fan changes from 40Hz to 38Hz, the frequency of the cooling fan decreases by 2Hz. If the original frequency of the cooling fan is 30Hz, then it is now 28Hz. If it changes from 40Hz to 40.4Hz or 39.6Hz, then the absolute value of r2 is 0.4 < k2, which is regarded as a small change, and the cooling fan is not adjusted temporarily.

[0069] In some embodiments, the control when the frequency of the regenerative air heater fan changes

[0070] Event trigger: When the set frequency value of the regenerative air heater fan changes, start to judge the difference before and after the change. When the absolute value of the difference is greater than the frequency fluctuation threshold k3 of the regenerative air heater fan (the parameter can be changed, default 0.5), output according to the formula, otherwise, the output is 0.

[0071] When the absolute value of the frequency fluctuation value r3 of the regenerative air heater fan is greater than the frequency fluctuation threshold k3 of the regenerative air heater fan, increase the frequency of the cooling fan by the third frequency change value Δy3 on the basis of the frequency set value, as follows:

[0072] r3 = sp - sp1

[0073] If |r3| > k3 then

[0074] Δy3 = p3 * r3

[0075] Else

[0076] Δy3 = 0

[0077] End

[0078] sp is the current frequency setting value of the reheating fan, sp1 is the last frequency setting value of the reheating fan; r3 is the deviation between the two settings, that is, the difference sp1 obtained by subtracting the last frequency setting value from the current frequency setting value sp of the reheating fan;

[0079] The third frequency variation value Δy3 is a value obtained by multiplying the frequency fluctuation value r3 of the regenerative fan by the third coefficient p3.

[0080] In some embodiments, the third coefficient has a value range of 0-3, preferably p3=0.8.

[0081] In some embodiments, the cooling end hood temperature is supplemented by the control

[0082] Event triggering, condition 1: when the regulating valve of the air box in the first cooling section is 90% open and the regulating valve of the air box in the second cooling section is 10% open, the terminal hood temperature is too high, that is, the terminal hood temperature is higher than the second temperature threshold, and the frequency of the cooling fan is increased; condition 2: when the regulating valve of the air box in the first cooling section is 10% open and the regulating valve of the air box in the second cooling section is 90% open, the terminal hood temperature is too low, that is, the terminal hood temperature is lower than the first temperature threshold, and the frequency of the cooling fan is reduced.

[0083] Set the target temperature to sp, the actual temperature to pv, and the dead zone to d, then:

[0084] When condition 1 or condition 2 is met: Δy4 = k4*((pv-sp) / 3d), otherwise Δy4 = 0.

[0085] Δy4 is the fourth frequency change value, k4 is the fourth coefficient;

[0086] When the valve opening of the air box in the first cooling section and the second cooling section causes the temperature of the end hood of the roaster to be lower than the first temperature threshold or higher than the second temperature threshold due to the setting of the opening of the air box, the frequency of the cooling fan is increased by the fourth frequency change value Δy4 on the basis of the frequency setting value;

[0087] In some embodiments, when the cycle t ends, the target temperature sp = 320°, the actual temperature pv = 300°, the dead zone d = 10, k4 = 0.6, then Δy4 = 0.6*(300-320) / (3*10) = -0.4Hz, that is, the cooling fan frequency is reduced by 0.4Hz. When condition 1 or condition 2 is met, Δy4 = 0.4, when condition 1 or condition 2 is not met, Δy4 = 0.

[0088] In some embodiments, the automatic control of the hood pressure in the roasting section

[0089] The pressure change of the smoke hood in the roasting section is used as one of the factors affecting the frequency of the cooling fan. Cycle trigger, set the cycle to t (1 to 300 seconds, default 30 seconds)

[0090] sp is the smoke hood pressure setting value, pv is the smoke hood detection pressure, dead zone d, p trend coefficient, m single maximum adjustment amount; pv middle is the PV value at 5 seconds; pv end is the PV value at 30 seconds; e1 is the target deviation, e2 trend deviation, e3 is the comprehensive error, among which e1 = sp-pv end, e2 = pv middle-pv end, e3 = e1+p*e2.

[0091] If(abs(e1)-d)>0then

[0092] Δy5=m*e3 / abs(e3)*(abs(e3)-d) / (3*d)

[0093] Else

[0094] Δy5=0

[0095] End

[0096] Δy5 is the fifth frequency change value, that is, the cooling fan frequency change value that needs to be adjusted when the hood pressure changes, and abs(.) is the absolute value function;

[0097] In some embodiments, sp = -150 Pa, pv = -80 Pa, d = 30 Pa, m = 0.5 Hz, p = 1.0, pmed = -100, then e1 = -70, e2 = -100-(-80) = -20, e3 = -70+1*(-20) = -90. Since the absolute value of e1 is 70, which is greater than the dead zone 30, according to the formula Δy5 = 0.5*(-90) / 90*(90-30) / (3*30) = 0.34 Hz.

[0098] In some embodiments, intelligent control of cooling fans

[0099] Determine the frequency fluctuation value Δy of the cooling fan, and combine it with the previous frequency setting value y0 of the cooling fan to construct the initial frequency output setting value y of the cooling fan. Then set a limit function of the value range around the initial frequency output setting value y of the cooling fan to determine the final frequency output setting value Y of the cooling fan, as follows:

[0100] The frequency variation of the cooling fan (i.e. the frequency fluctuation value of the cooling fan) is:

[0101] Δy=Δy1+Δy2+Δy3+Δy4+Δy5

[0102] See above for detailed explanation of Δy1, Δy2, Δy3, Δy4, and Δy5

[0103] The initial setting value of the cooling fan frequency output is y=y0+Δy

[0104] Where y0 is the previous frequency, and the upper and lower limits are set for each output. The cooling fan frequency is:

[0105] Y=limit(min, y, max).

[0106] In some embodiments, Limit is a limiting function. When the value y exceeds the maximum value (max), Y takes the maximum value; when it falls below the minimum value, Y takes the minimum value. This is commonly used in the field of automated control for safety reasons. For example, if min = 20 and max = 30, the final value of Y can only be between 20 and 30. That is, when y = 31 or 19, Y can only take the values ​​of 30 and 20.

[0107] In some embodiments, the temperature of the hood at the end of the cooling section is automatically controlled

[0108] The cooling section end temperature is primarily regulated by changing the cooling air volume distribution. This is done to minimize the impact on other control objects. The cooling air volume is changed only when the air volume distribution method fails. The specific control logic is as follows: Figure 5 As shown, periodic control is adopted. When the control cycle ends, the deviation between the actual temperature (pv value in the figure) and the target temperature (sp value in the figure) is determined.

[0109] When the pv-sp value is greater than the dead zone (d value in the figure, usually 2-5% of the set value), it means that the actual temperature is too high. At this time, it is necessary to increase the air volume of the first cooling section, that is, increase Figure 1 The opening of the regulating valve 1 and regulating valve 2 (corresponding to Figure 5 v1 and v2 in), when v 1+ When the opening of v2 is greater than 195%, it means that the valve of the first cooling section is basically in the fully open state. If the deviation still exists, it is necessary to adjust the regulating valve of the second cooling section ( Figure 5 v3 in ).

[0110] When the pv-sp value is less than the negative dead zone (d value in the figure, usually 2-5% of the set value), it means that the actual temperature is too low. At this time, it is necessary to reduce the air volume of the first cooling section and increase the air volume of the second cooling section, that is, increase Figure 1 The opening of the regulating valve 3 in Figure 5 When the opening of v3 is greater than 95%, it means that the valve of the second cooling section is basically in the fully open state. If the deviation still exists, it is necessary to adjust the regulating valve of the first cooling section ( Figure 5 v2 in ).

[0111] In some embodiments, at the end of the cycle, sp=320, pv=300, d=10, pv-sp=300-320=-20, which is less than -10, then v3 increases the valve position to k=3. If the v3 valve position is 50% before the cycle, then at the end of the cycle, v3=53%, and the timing is restarted to start a new cycle adjustment. When the valve position v3>95%, the above conditions still hold, then v1 and v2 are reduced, that is, v1 and v2 are both reduced to 47%.

[0112] When sp = 320, pv = 311 or 329, pv-sp = -9 or 9, not less than the negative dead zone or greater than the dead zone, the valve position v3 remains unchanged;

[0113] When Sp=320, pv=331, pv-sp=11 is greater than the dead zone, and the valve positions before v1 and v2 are adjusted are both 50%. Then at the end of the cycle, v1=53, v2=53. Re-time, if v1+v2>195, the valve position minus v3 will change from 50% to 47%.

[0114] The present invention distributes the cooling air volume to different wind boxes by automatically regulating the frequency of the cooling fan and the valve of the wind box, so as to optimize the smoke hood pressure of the roasting section and the smoke hood temperature at the end of the cooling section of the roasting machine, thereby realizing fully automatic intelligent cooling control and realizing intelligent automatic control that replaces manual operation.

[0115] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A cooling control method, applicable to a roasting machine, characterized in that: The method comprises the following steps: distributing the cooling air volume to different wind boxes by regulating the frequency of the cooling fan and the valve of the wind box, so as to optimize the hood pressure of the roasting section and the hood temperature at the end of the cooling section of the roasting machine; The frequency of the cooling fan and the valve of the bellows are both automatically regulated, and the state of the valve of the bellows includes a fully open state and a partially open state; The roaster includes a drying section, a preheating section, a roasting section, a soaking section, and a cooling section. The cooling section includes a first cooling section and a second cooling section. The air in the first cooling section penetrates the material layer of the roaster and enters the soaking section, the roasting section, and the preheating section, and is then extracted by the main exhaust fan and the reheating fan. The air in the second cooling section cools the pellets in the roaster and then enters the drying section through the drying fan to dry the pellets. The cooling fan and the valve of the wind box serve as main components of a plurality of wind boxes, and the plurality of wind boxes are arranged in the cooling section of the roaster and distributed at the end of the roaster.

2. The cooling control method according to claim 1, characterized in that: When the absolute value of the speed fluctuation value of the roasting machine is greater than the roasting machine speed fluctuation threshold, the frequency of the cooling fan is increased by a first frequency change value on the basis of the frequency setting value; The speed fluctuation value of the roasting machine is the difference between the current speed setting value of the roasting machine and the previous speed setting value; The first frequency change value is a value obtained by multiplying the speed fluctuation value of the roasting machine by a first coefficient.

3. The cooling control method according to claim 2, characterized in that: When the absolute value of the frequency fluctuation value of the main exhaust fan is greater than the main exhaust fan frequency fluctuation threshold, the frequency of the cooling fan is increased by a second frequency change value on the basis of the frequency setting value; The frequency fluctuation value of the main exhaust fan is the difference between the current frequency setting value of the main exhaust fan and the previous frequency setting value; The second frequency change value is a value obtained by multiplying the frequency fluctuation value of the main exhaust fan by a second coefficient.

4. The cooling control method according to claim 1, characterized in that: When the absolute value of the frequency fluctuation value of the regenerative fan is greater than the regenerative fan frequency fluctuation threshold, increasing the frequency of the cooling fan by a third frequency change value on the basis of the frequency setting value; The frequency fluctuation value of the reheating fan is the difference between the current frequency setting value of the reheating fan and the previous frequency setting value; The third frequency change value is a value obtained by multiplying the frequency fluctuation value of the heat recovery fan by a third coefficient.

5. The cooling control method according to claim 1, characterized in that: When the valve openings of the air boxes in the first cooling section and the second cooling section cause the temperature of the end hood of the roaster to be lower than the first temperature threshold or higher than the second temperature threshold due to the setting of the openings of the air boxes, the frequency of the cooling fan is increased by a fourth frequency variation value based on the frequency setting value; The fourth frequency change value is determined based on the temperature difference of the terminal smoke hood and the dead zone ratio.

6. The cooling control method according to claim 1, characterized in that: The change of the smoke hood pressure in the roasting section is used as one of the influencing factors for regulating the frequency of the cooling fan.

7. The cooling control method according to claim 1, characterized in that: Determine the frequency fluctuation value of the cooling fan, and in combination with the previous frequency setting value of the cooling fan, construct the initial setting value of the frequency output of the cooling fan, and set a limit function of the value range around the initial setting value of the frequency output of the cooling fan to determine the final setting value of the frequency output of the cooling fan.

8. The cooling control method according to claim 2, characterized in that: The first coefficient has a value range of 0-10.

9. The cooling control method according to claim 3, characterized in that: The second coefficient has a value range of 0-3.

10. The cooling control method according to claim 4, characterized in that: The third coefficient has a value range of 0-3.

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