Feedback control method and control system for moisture content at outlet of tofu drying machine

Abstract

The present invention discloses a moisture feedback control method for a wire drying machine outlet, comprising the following steps: presetting a standard value of moisture after cooling SP1 on a PID controller for moisture after cooling, and presetting a standard value of moisture after drying SP2 on a PID controller for moisture after drying; measuring an actual value of moisture after cooling PV1, and calculating a correction value of moisture after cooling CV1; measuring an actual value of moisture after drying PV2 at the outlet of a wire drying machine discharging vibration conveyor, and calculating a correction value of moisture after drying CV2; calculating a moisture correction value X by using a moisture correction value selection rule for the moisture correction value CV1 and the moisture correction value CV2, and transmitting the moisture correction value X as final feedback data to the wire drying machine to control the moisture at the outlet of the wire drying machine; the present invention also discloses a control system, comprising a wire drying machine, a cooling air selection device, a PID controller for moisture after cooling, a PID controller for moisture after drying, and a control unit for a wire drying machine. The present invention has the beneficial effects of improving the moisture detection accuracy of the wire drying machine and accelerating the feedback speed of control information.

Description

Technical Field

[0001] The invention relates to a moisture feedback control method and a control system for a tobacco cutter drying machine outlet, belonging to the technical field of tobacco cutter making. Background Art

[0002] The working principle commonly adopted by the cigarette cutting and drying machine is: a certain flow of steam passes through the inner wall of the cylinder thin plate, the steam condenses in the steam duct so that the heat is effectively transferred to the thin plate and then to the tobacco. At the same time, the fan sends ambient air into the hot air generated by the steam-heated heat exchanger. While flowing through the drum, the hot air is transferred to the tobacco by convection and takes away moisture, so that the tobacco can be evenly dried, evenly heated, and the filling force is evenly increased, as well as constant outlet moisture and temperature.

[0003] In the traditional cigarette production line, an online moisture meter is set at the outlet of the wire drying machine discharging vibration conveyor to measure the moisture after drying at the outlet of the wire drying machine; a cooling air separation device is set downstream of the wire drying machine, and an online moisture meter is also set after the cooling air separation device to measure the moisture after cooling at the outlet of the cooling air separation device. Due to different processing technologies and quality requirements, different factories usually choose to use the sample values ​​of moisture after drying or moisture after cooling as feedback data to control the moisture at the outlet of the wire drying machine. If the sample value of moisture after drying is used as the feedback data to control the moisture at the outlet of the wire drying machine, although the moisture at the outlet of the wire drying machine can be quickly fed back and controlled, the entire control process is sensitive and responsive, but the problem is that the center value of moisture often deviates from the standard value, resulting in over-adjustment and overshoot; if the sample value of moisture after cooling is used as the feedback data to control the moisture at the outlet of the wire drying machine, although the moisture can be accurately fed back and controlled, the entire control result is accurate, with small fluctuations and no over-adjustment, the problems are slow feedback control speed, lag in adjustment, and too long adjustment cycle. That is, from the traditional fluctuation trend of sample data, the shapes of the fluctuation trend graphs of the fast feedback control mode and the accurate feedback control mode are similar, the former has a larger disturbance, and the latter has a larger lag.

[0004] Therefore, as an improvement, some factories choose the cascade feedback control mode, cascading the moisture PID after cooling and the moisture PID after drying, and feeding back the corrected final value after the cascade calculation of the two PID modules to the dryer for moisture control. This method is difficult to debug, and the two PID parameters need to be cascaded and debugged at the same time, and the PID setting parameters need to test multiple batches of materials. At the same time, the parameters of the two PID modules need to be constantly corrected according to changes in the production site. After practical use, it was found that the feedback control mode requires multiple process indicators, equipment parameters and physical processing status of the entire section equipment of the solidified dryer equipment and cooling equipment. This control mode has high requirements for the factory and is difficult to promote.

[0005] Therefore, a new and innovative control method is needed to achieve a stable control method and control system for the moisture content of the material at the outlet of the silk drying machine. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a control method with wide applicability and easy promotion to achieve a stable control method for the moisture content of the material at the outlet of the silk drying machine, so as to improve the accuracy of moisture detection, speed up the information feedback speed, and improve the accuracy and stability of moisture control of the equipment.

[0007] The present invention provides a moisture feedback control method for a tofu drying machine outlet, characterized in that the method comprises the following steps:

[0008] Step 1, setting a post-cooling moisture PID controller and a post-drying moisture PID controller, and presetting a post-cooling moisture standard value SP1 on the post-cooling moisture PID controller, and presetting a post-drying moisture standard value SP2 on the post-drying moisture PID controller;

[0009] Step 2, measuring the actual value PV1 of the moisture after cooling at the outlet of the cooling air separation equipment, transmitting the actual value PV1 of the moisture after cooling to the moisture after cooling PID controller, and calculating the correction value CV1 of the moisture after cooling;

[0010]

[0011] In the formula, the difference between (SP1-PV1) is the input deviation of PID, K p1 is the proportional coefficient of the PID module, T i1 is the integral time constant of the PID module, T d1 is the differential time constant of the PID module. Represents the output value of the continuous PID module formula. In the actual engineering application process, due to the discreteness of computer programming operation cycles and data, the actual calculated value of CV1 value in the PLC program will use some approximate algorithms or range conversion algorithms. The function f(x) in the formula represents the approximate algorithm and range conversion algorithm in the PLC program without changing the calculation structure of proportion, integration and differentiation. The function f(x) controls the output value range in the interval (0, R), where R represents a certain positive real number, ensuring that the PID output CV1 value controls the moisture after cooling in the form of a positive percentage. Wherein, CV1 initial Represents the initial value of CV1 in the program.

[0012] The actual value PV2 of moisture after drying at the outlet of the drying machine vibrating conveyor is measured and transmitted to the moisture after drying PID controller, and the moisture after drying correction value CV2 is calculated;

[0013]

[0014] In the formula, the difference between (SP2-PV2) is the input deviation of PID, K p2 is the proportional coefficient of the PID module, T i2 is the integral time constant of the PID module, T d2 It is the differential time constant of the PID module.

[0015] in Represents the output value of the continuous PID module formula. In the actual engineering application process, due to the discreteness of computer programming operation cycles and data, the actual calculated value of CV2 value in the PLC program will use some approximate algorithms or range conversion algorithms. The function f(x) in the formula represents the approximate algorithm and range conversion algorithm in the PLC program without changing the calculation structure of proportion, integration and differentiation. The function f(x) controls the output value range in the interval (0, R), where R represents a certain positive real number, ensuring that the PID output CV2 value controls the cylinder wall temperature in the form of a positive percentage. Wherein, CV2 initial Represents the initial value of CV2 in the program.

[0016] Step 3: The moisture correction value X is calculated from the moisture correction value CV1 after cooling and the moisture correction value CV2 after drying according to the moisture correction value selection rule. The moisture correction value X is transmitted to the wire drying machine as the final feedback data to control the moisture at the outlet of the wire drying machine. Usually, the moisture correction value selection rule is calculated in the PLC hardware module of the equipment in the form of code programming. Among them, the moisture correction value selection rule is as follows:

[0017] ① When the actual moisture value PV1 after cooling and the actual moisture value PV2 after baking are stable, the moisture correction value X satisfies the following formula:

[0018] X = CV1*a+CV2*b (3);

[0019] Wherein, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; a+b=1,0≤a≤1,0≤b≤1;

[0020] The definition of PV1 and PV2 stability is: PV1 and PV2 values ​​continue for N 1 The deviation of the center standard value is less than the threshold value G 1 PV1 and PV2 value data change slowly. Accumulate the change value of PV1 and PV2 value sample data every cycle. After accumulating 10 times, the slowest change value of PV1 and PV2 value data is N 2 The sum of the change values ​​of the cycles is less than the threshold G 2 ;

[0021] Define the sample value of the ith period of PV1 and PV2 as V i ,but:

[0022] The change value of PV1 and PV2 value sample data every cycle = |sample value of this cycle - sample value of the previous cycle| = |V i -V i-1 | (4);

[0023]

[0024] PV1, PV2 values ​​continue for N 1 The deviation of the center standard value is less than the threshold value G 1 The formula is:

[0025] |N 1 Maximum value within one second - center standard value |<threshold G 1 (6);

[0026] |Center Standard Value-N 1 Minimum value within seconds|<threshold G 1 (7);

[0027] The formula for the slow change of PV1 and PV2 value data is:

[0028]

[0029] ② When the actual moisture value after cooling PV1 or the actual moisture value after baking PV2 continues for N 1 When the seconds deviate from the center value, the following rules apply:

[0030] <1> If only the actual value of moisture after cooling PV1 lasts N 1 When the second deviates from the center value, the moisture correction value X satisfies the following formula:

[0031] X=CV1*(a+y1)+CV2*(b-y1) (9);

[0032] y1=A1*k1=(PV1-SP1)*k1 (10);

[0033] Wherein, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; k1 is the correction coefficient; A1 is the moisture deviation value after cooling; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y1 is the correction value of moisture deviation effect after cooling on the weight coefficient; k1 is the correction coefficient of moisture deviation effect after cooling; a+b=1, 0≤a≤1, 0≤b≤1;

[0034] If b-y1<0, that is, the weight of (b-y1) is less than 0, then y1 is assigned to b, then b-y1=bb=0, a+y1=a+b=1, and CV2 is not required to provide feedback. X is fully fed back by CV1, and formula (9) is simplified to:

[0035] X = CV1 (11);

[0036] <2> If only the actual value of moisture after drying PV2 lasts N 1 When the second deviates from the center value, the moisture correction value X satisfies the following formula:

[0037] X=CV1*(a-y2)+CV2*(b+y2) (12);

[0038] y2=A2*k2=(PV2-SP2)*k2 (13);

[0039] Wherein, a+b=1,0≤a≤1,0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y2 is the correction value of the weight coefficient for the moisture deviation effect after baking; k2 is the correction coefficient for the moisture deviation effect after baking;

[0040] If a-y2<0, that is, the weight of (a-y2) is less than 0, then y2 is assigned a, then a-y2=aa=0, b+y2=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (12) is simplified to:

[0041] X = CV2 (14);

[0042] <3> If the actual moisture value after cooling PV1 and the actual moisture value after baking PV2 are both continuous N 1 When the moisture content deviates from the center value by 1 second, the moisture correction value X satisfies formula (3):

[0043] X=CV1*a+CV2*b (3)

[0044] Wherein, a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking;

[0045] The actual moisture value PV1 after cooling or the actual moisture value PV2 after baking deviates from the center value for N seconds, which is defined as the value of PV1 or PV2 deviating from the center value for N seconds. 1 The deviation from the center standard value is greater than or equal to the threshold G 1 , the formula is:

[0046] |N 1Maximum value within a second - central standard value | ≥ threshold G 1 (15);

[0047] or,

[0048] |Center Standard Value-N 1 Minimum value within seconds | ≥ threshold G 1 (16);

[0049] ③ When the actual moisture value PV1 after cooling or the actual moisture value PV2 after baking changes too fast and the above ① and ② situations do not exist (continuous N 1 When the value deviates from the center by more than one second, the following formula is used:

[0050] If only the actual moisture value PV1 after cooling changes too fast, the moisture correction value X satisfies the following formula:

[0051] X=CV1*(a-y3)+CV2*(b+y3) (17);

[0052] y3=A2*k3=(PV2-SP2)*k3 (18);

[0053] Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y3 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after cooling; k3 is the correction coefficient when moisture data after cooling changes too fast;

[0054] If a-y3<0, that is, the weight of (a-y3) is less than 0, then y3 is assigned a, then a-y3=aa=0, b+y3=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (17) is simplified to:

[0055] X=CV2 (14)

[0056] ii. If only the actual value PV2 of moisture after drying changes too fast, then:

[0057] X=CV1*(a+y4)+CV2*(b-y4) (19);

[0058] y4=A1*k4=(PV1-SP1)*k4 (20);

[0059] Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y4 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after baking; k4 is the correction coefficient when moisture data after baking changes too fast;

[0060] If b-y4<0, that is, the weight of (b-y4) is less than 0, then y4 is assigned to b, then b-y4=bb=0, a+y4=a+b=1, at this time, CV2 is not required for feedback, and X is fully fed back by CV1, then formula (19) is simplified to:

[0061] X = CV1 (11);

[0062] ⅲ When the actual value of moisture after cooling PV1 and the actual value of moisture after baking PV2 change too fast at the same time, then:

[0063] X = CV1 (11);

[0064] Among them, the actual value of moisture after cooling PV1 or the actual value of moisture after baking PV2 data changes too fast, which is defined as N 2 The sum of the change values ​​of the cycles is greater than or equal to the threshold G 2 , the formula is:

[0065]

[0066] A control system described in the present invention is characterized by comprising a wire drying machine, a cooling and air separation device, a PID controller for moisture after cooling, a PID controller for moisture after drying, and a wire drying machine control unit;

[0067] The inlet of the silk drying machine is connected to the outlet of the moisture conditioning machine, and a moisture meter after drying is installed at the outlet of the silk drying machine's discharging vibration conveyor, which is used to measure the moisture after drying at the outlet of the silk drying machine's discharging vibration conveyor;

[0068] The cooling air selection device is arranged downstream of the tobacco drying machine, the inlet of the cooling air selection device is connected to the outlet of the tobacco drying machine, the outlet of the cooling air selection device is connected to the post-process of the tobacco production line, and the outlet of the cooling air selection device is equipped with a post-cooling moisture meter for measuring the post-cooling moisture at the outlet of the cooling air selection device;

[0069] The post-cooling moisture PID controller is connected to the post-cooling moisture meter and the wire drying machine control unit. The post-cooling moisture PID controller calculates the post-cooling moisture actual value PV1 as the process value and the post-cooling moisture standard value SP1 as the set value, and transmits the calculated post-cooling moisture correction value CV1 to the wire drying machine control unit.

[0070] The post-drying moisture PID controller is connected to the post-drying moisture meter and the wire drying machine control unit. The post-drying moisture PID controller calculates the post-drying moisture actual value PV2 as the process value and the post-drying moisture standard value SP1 as the set value, and transmits the calculated post-drying moisture correction value CV2 to the wire drying machine control unit.

[0071] The wire drying machine control unit is connected to the moisture after cooling PID controller, the moisture after drying PID controller and the wire drying machine, and is used to calculate the moisture correction value X by the moisture correction value selection rule of the moisture after cooling CV1 and the moisture after drying CV2. The moisture correction value X is transmitted to the wire drying machine as the final feedback data to control the moisture at the outlet of the wire drying machine.

[0072] The beneficial effects of the present invention are:

[0073] 1) The formulas and parameters defined in this complex control method are assigned in the form of percentage weights to combine the above two in a regular manner, combining and improving the fast feedback control mode and the accurate feedback control mode, eliminating disturbance and hysteresis, making the moisture feedback value at the outlet of the silk-drying machine as close to the theoretical optimal value as possible, improving the moisture detection accuracy of the silk-drying machine, and accelerating the feedback speed of control information;

[0074] 2) The control method of the present invention defines mathematical formulas for two control forms: moisture after baking, moisture after cooling deviating from the center value, and data changing too fast, and assigns different control rules and calculation formulas for feedback data for each situation, making the applicability of the present invention stronger;

[0075] 3) The related parameters of the two PID controllers involved in the present invention do not need to be coordinated and debugged, and can be determined by isolated single closed-loop feedback debugging; the parameters of the formula related to the moisture correction value involved in the present invention are linear attribute parameters, and the methods for establishing the related parameters are diverse and simple, so the parameters of the method of the present invention are easy to debug and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 It is a simplified diagram of the control method of the present invention;

[0077] Figure 2 This is the moisture correction value selection rule of the present invention. DETAILED DESCRIPTION

[0078] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0079] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0080] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0081] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0082] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0085] The present invention will be described in detail below in conjunction with exemplary embodiments with reference to the accompanying drawings.

[0086] The present invention provides a moisture feedback control method for a tofu drying machine outlet, the method comprising the following steps:

[0087] Step 1, setting a post-cooling moisture PID controller and a post-drying moisture PID controller, and presetting a post-cooling moisture standard value SP1 on the post-cooling moisture PID controller, and presetting a post-drying moisture standard value SP2 on the post-drying moisture PID controller;

[0088] Step 2, measuring the actual value PV1 of the moisture after cooling at the outlet of the cooling air separation equipment, transmitting the actual value PV1 of the moisture after cooling to the moisture after cooling PID controller, and calculating the correction value CV1 of the moisture after cooling;

[0089]

[0090] In the formula, the difference between (SP1-PV1) is the input deviation of PID, K p1 is the proportional coefficient of the PID module, T i1 is the integral time constant of the PID module, T d1 is the differential time constant of the PID module. Represents the output value of the continuous PID module formula. In the actual engineering application process, due to the discreteness of computer programming operation cycles and data, the actual calculated value of CV1 value in the PLC program will use some approximate algorithms or range conversion algorithms. The function f(x) in the formula represents the approximate algorithm and range conversion algorithm in the PLC program without changing the calculation structure of proportion, integration and differentiation. The function f(x) controls the output value range in the interval (0, R), where R represents a certain positive real number, ensuring that the PID output CV1 value controls the moisture after cooling in the form of a positive percentage. Wherein, CV1 initial Represents the initial value of CV1 in the program.

[0091] The actual value PV2 of moisture after drying at the outlet of the drying machine vibrating conveyor is measured and transmitted to the moisture after drying PID controller, and the moisture after drying correction value CV2 is calculated;

[0092]

[0093] In the formula, the difference between (SP2-PV2) is the input deviation of PID, K p2 is the proportional coefficient of the PID module, T i2 is the integral time constant of the PID module, T d2 is the differential time constant of the PID module. Represents the output value of the continuous PID module formula. In the actual engineering application process, due to the discreteness of computer programming operation cycles and data, the actual calculated value of CV2 value in the PLC program will use some approximate algorithms or range conversion algorithms. The function f(x) in the formula represents the approximate algorithm and range conversion algorithm in the PLC program without changing the calculation structure of proportion, integration and differentiation. The function f(x) controls the output value range in the interval (0, R), where R represents a certain positive real number, ensuring that the PID output CV2 value controls the cylinder wall temperature in the form of a positive percentage. Wherein, CV2 initial Represents the initial value of CV2 in the program.

[0094] Step 3: The moisture correction value X is calculated from the moisture correction value CV1 after cooling and the moisture correction value CV2 after drying according to the moisture correction value selection rule. The moisture correction value X is transmitted to the wire drying machine as the final feedback data to control the moisture at the outlet of the wire drying machine. Usually, the moisture correction value selection rule is calculated in the PLC hardware module of the equipment in the form of code programming. Among them, the moisture correction value selection rule is as follows:

[0095] ① When the actual moisture value PV1 after cooling and the actual moisture value PV2 after baking are stable, the moisture correction value X satisfies the following formula:

[0096] X = CV1*a+CV2*b (3);

[0097] In the formula, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; a+b=1,0≤a≤1,0≤b≤1;

[0098] The definition of PV1 and PV2 stability is: PV1 and PV2 values ​​continue for N 1 The deviation of the center standard value is less than the threshold value G 1PV1 and PV2 value data change slowly. Accumulate the change value of PV1 and PV2 value sample data every cycle. After accumulating 10 times, the slowest change value of PV1 and PV2 value data is N 2 The sum of the change values ​​of the cycles is less than the threshold G 2 ;

[0099] Define the sample value of PV1 and PV2 in the i-th cycle as V i ,but:

[0100] The change value of PV1 and PV2 value sample data every cycle = |sample value of this cycle - sample value of the previous cycle| = |V i -V i-1 | (4);

[0101]

[0102] PV1, PV2 values ​​continue for N 1 The deviation of the center standard value is less than the threshold value G 1 The formula is expressed as:

[0103] |N 1 Maximum value within one second - center standard value |<threshold G 1 (6);

[0104] |Center Standard Value-N 1 Minimum value within seconds|<threshold G 1 (7);

[0105] The formula for the slow change of PV1 and PV2 value data is:

[0106]

[0107] ② When the actual moisture value after cooling PV1 or the actual moisture value after baking PV2 continues for N 1 When the seconds deviate from the center value, the following rules apply:

[0108] <1> If only the actual value of moisture after cooling PV1 lasts N 1 When the second deviates from the center value, the moisture correction value X satisfies the following formula:

[0109] X=CV1*(a+y1)+CV2*(b-y1) (9);

[0110] y1=A1*k1=(PV1-SP1)*k1 (10);

[0111] Wherein, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; k1 is the correction coefficient; A1 is the moisture deviation value after cooling; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y1 is the correction value of moisture deviation effect after cooling on the weight coefficient; k1 is the correction coefficient of moisture deviation effect after cooling; a+b=1, 0≤a≤1, 0≤b≤1;

[0112] If b-y1<0, that is, the weight of (b-y1) is less than 0, then y1 is assigned to b, then b-y1=bb=0, a+y1=a+b=1, and CV2 is not required to provide feedback. X is fully fed back by CV1, and formula (9) is simplified to:

[0113] X = CV1 (11);

[0114] <2> If only the actual value of moisture after drying PV2 lasts N 1 When the second deviates from the center value, the moisture correction value X satisfies the following formula:

[0115] X=CV1*(a-y2)+CV2*(b+y2) (12);

[0116] y2=A2*k2=(PV2-SP2)*k2 (13);

[0117] Wherein, a+b=1,0≤a≤1,0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y2 is the correction value of the weight coefficient for the moisture deviation effect after baking; k2 is the correction coefficient for the moisture deviation effect after baking;

[0118] If a-y2<0, that is, the weight of (a-y2) is less than 0, then y2 is assigned a, then a-y2=aa=0, b+y2=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (12) is simplified to:

[0119] X = CV2 (14);

[0120] <3> If the actual moisture value after cooling PV1 and the actual moisture value after baking PV2 are both continuous N 1 When the moisture content deviates from the center value by 1 second, the moisture correction value X satisfies formula (1):

[0121] X=CV1*a+CV2*b (3)

[0122] Wherein, a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking;

[0123] The actual moisture value PV1 after cooling or the actual moisture value PV2 after baking deviates from the center value for N seconds, which is defined as the value of PV1 or PV2 deviating from the center value for N seconds. 1 The deviation from the center standard value is greater than or equal to the threshold G 1 , the formula is:

[0124] |N 1 Maximum value within a second - central standard value | ≥ threshold G 1 (15);

[0125] or,

[0126] |Center Standard Value-N 1 Minimum value within seconds | ≥ threshold G 1 (16);

[0127] ③ When the actual moisture value PV1 after cooling or the actual moisture value PV2 after baking changes too fast and the above ① and ② situations do not exist (continuous N 1 When the value deviates from the center by more than one second, the following formula is used:

[0128] If only the actual moisture value PV1 after cooling changes too fast, the moisture correction value X satisfies the following formula:

[0129] X=CV1*(a-y3)+CV2*(b+y3) (17);

[0130] y3=A2*k3=(PV2-SP2)*k3 (18);

[0131] Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y3 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after cooling; k3 is the correction coefficient when moisture data after cooling changes too fast;

[0132] If a-y3<0, that is, the weight of (a-y3) is less than 0, then y3 is assigned a, then a-y3=aa=0, b+y3=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (17) is simplified to:

[0133] X=CV2 (14)

[0134] ii. If only the actual value PV2 of moisture after drying changes too fast, then:

[0135] X=CV1*(a+y4)+CV2*(b-y4) (19);

[0136] y4=A1*k4=(PV1-SP1)*k4 (20);

[0137] Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y4 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after baking; k4 is the correction coefficient when moisture data after baking changes too fast;

[0138] If b-y4<0, that is, the weight of (b-y4) is less than 0, then y4 is assigned to b, then b-y4=bb=0, a+y4=a+b=1, at this time, CV2 is not required for feedback, and X is fully fed back by CV1, then formula (19) is simplified to:

[0139] X = CV1 (11);

[0140] ⅲ When the actual value of moisture after cooling PV1 and the actual value of moisture after baking PV2 change too fast at the same time, then:

[0141] X = CV1 (11);

[0142] Among them, the actual value of moisture after cooling PV1 or the actual value of moisture after baking PV2 data changes too fast, which is defined as N 2 The sum of the change values ​​of the cycles is greater than or equal to the threshold G 2 , the formula is:

[0143]

[0144] A control system described in the present invention comprises a wire drying machine 1, a cooling and air separation device 2, a post-cooling moisture PID controller 3, a post-drying moisture PID controller 4 and a wire drying machine control unit 5;

[0145] The inlet of the silk drying machine 1 is connected to the outlet of the moisture conditioning machine, and the outlet of the silk drying machine's discharging vibration conveyor is equipped with a post-drying moisture meter 6 for measuring the post-drying moisture at the outlet of the silk drying machine's discharging vibration conveyor;

[0146] The cooling air selection device 2 is arranged downstream of the tobacco drying machine 1, the inlet of the cooling air selection device 2 is connected to the outlet of the tobacco drying machine 1, and the outlet of the cooling air selection device 2 is connected to the post-process 8 of the tobacco production line. The outlet of the cooling air selection device 2 is equipped with a post-cooling moisture meter 7 for measuring the post-cooling moisture at the outlet of the cooling air selection device.

[0147] The post-cooling moisture PID controller 3 is connected to the post-cooling moisture meter 7 and the wire drying machine control unit 5. The post-cooling moisture PID controller 3 calculates the post-cooling moisture actual value PV1 as a process value and the post-cooling moisture standard value SP1 as a set value, and transmits the calculated post-cooling moisture correction value CV1 to the wire drying machine control unit 5;

[0148] The post-drying moisture PID controller 4 is connected to the post-drying moisture meter 6 and the wire drying machine control unit 5. The post-drying moisture PID controller 4 calculates the post-drying moisture actual value PV2 as a process value and the post-drying moisture standard value SP1 as a set value, and transmits the calculated post-drying moisture correction value CV2 to the wire drying machine control unit 5;

[0149] The wire drying machine control unit 5 is connected to the post-cooling moisture PID controller 3, the post-drying moisture PID controller 4 and the wire drying machine 1, and is used to calculate the moisture correction value X by using the post-cooling moisture correction value CV1 and the post-drying moisture correction value CV2 according to the moisture correction value selection rule. The moisture correction value X is transmitted to the wire drying machine 1 as the final feedback data to control the moisture at the outlet of the wire drying machine.

[0150] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A moisture feedback control method for a tofu drying machine outlet, characterized in that: The method comprises the following steps: Step 1, setting a post-cooling moisture PID controller and a post-drying moisture PID controller, and presetting a post-cooling moisture standard value SP1 on the post-cooling moisture PID controller, and presetting a post-drying moisture standard value SP2 on the post-drying moisture PID controller; Step 2: Determine the actual value PV1 of the moisture after cooling at the outlet of the cooling air separation equipment, transmit the actual value PV1 of the moisture after cooling to the moisture after cooling PID controller, and calculate the correction value CV1 of the moisture after cooling: in Represents the output value of the continuous PID module formula; CV1 initial Represents the initial value of CV1 in the program; where the difference (SP1-PV1) is the input deviation of PID, K p1 is the proportional coefficient of the PID module, T i1 is the integral time constant of the PID module, T d1 is the differential time constant of the PID module; The actual moisture value PV2 after drying at the outlet of the drying machine vibration conveyor is measured and transmitted to the moisture PID controller after drying, and the moisture correction value CV2 after drying is calculated: Represents the output value of the continuous PID module formula; CV2 initial Represents the initial value of CV2 in the program; where the difference (SP2-PV2) is the input deviation of PID, K p2 is the proportional coefficient of the PID module, T i2 is the integral time constant of the PID module, T d2 is the differential time constant of the PID module; Step 3: The moisture correction value X is calculated by the moisture correction value selection rule based on the moisture correction value CV1 after cooling and the moisture correction value CV2 after drying. The moisture correction value X is transmitted to the wire drying machine as the final feedback data to control the moisture at the outlet of the wire drying machine. The moisture correction value selection rule is as follows: ① When the actual moisture value PV1 after cooling and the actual moisture value PV2 after baking are stable, the moisture correction value X satisfies the following formula: X = CV1*a+CV2*b(3); In the formula, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; a+b=1,0≤a≤1,0≤b≤1; The definition of PV1 and PV2 value stability is: the deviation of PV1 and PV2 values ​​from the central standard value for N1 seconds is less than the threshold G1, and the data of PV1 and PV2 values ​​change slowly. The change values ​​of PV1 and PV2 value sample data after each cycle are accumulated. After accumulating 10 times, the data of PV1 and PV2 values ​​change slowly, that is, the sum of the change values ​​of N2 cycles is less than the threshold G2; Define the sample value of PV1 and PV2 in the i-th cycle as V i ,but: The change value of PV1 and PV2 value sample data every cycle = |sample value of this cycle - sample value of the previous cycle| = |V i -V i-1 |(4); The formula for the deviation of PV1 and PV2 values ​​from the center standard value for N1 seconds and less than the threshold value G1 is: Maximum value within N1 seconds - central standard value < threshold G1 (6); Center standard value - minimum value within N1 seconds < threshold G1 (7); The formula for the slow change of PV1 and PV2 value data is: ② When the actual moisture value PV1 after cooling or the actual moisture value PV2 after baking deviates from the center value for N1 seconds, the following rules are adopted: <1> If the actual moisture value PV1 after cooling deviates from the center value for N1 seconds, the moisture correction value X satisfies the following formula: X=CV1*(a+y1)+CV2*(b-y1)(9); y1=A1*k1=(PV1-SP1)*k1(10); Wherein, CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; k1 is the correction coefficient; A1 is the moisture deviation value after cooling; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y1 is the correction value of moisture deviation effect after cooling on the weight coefficient; k1 is the correction coefficient of moisture deviation effect after cooling; a+b=1, 0≤a≤1, 0≤b≤1; If b-y1<0, that is, the weight of (b-y1) is less than 0, then y1 is assigned to b, then b-y1=bb=0, a+y1=a+b=1, and CV2 is not required to provide feedback. X is fully fed back by CV1, and formula (9) is simplified to: X = CV1(11); <2> If the actual moisture value PV2 after drying deviates from the center value for N1 seconds, the moisture correction value X satisfies the following formula: X=CV1*(a-y2)+CV2*(b+y2)(12); y2=A2*k2=(PV2-SP2)*k2(13); Wherein, a+b=1,0≤a≤1,0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y2 is the correction value of the weight coefficient for the moisture deviation effect after baking; k2 is the correction coefficient for the moisture deviation effect after baking; If a-y2<0, that is, the weight of (a-y2) is less than 0, then y2 is assigned a, then a-y2=aa=0, b+y2=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (12) is simplified to: X = CV2(14); <3> If the actual moisture value PV1 after cooling and the actual moisture value PV2 after baking deviate from the center value for N1 seconds at the same time, the moisture correction value X satisfies formula (3): X=CV1*a+CV2*b(3) Wherein, a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; The actual moisture value PV1 after cooling or the actual moisture value PV2 after baking deviates from the center value for N seconds, which is defined as the deviation of PV1 and PV2 from the center standard value for N1 seconds is greater than or equal to the threshold G1. The formula is: Maximum value within N1 seconds - central standard value ≥ threshold G1 (15); or, Center standard value - minimum value within N1 seconds ≥ threshold G1 (16); ③ When the actual moisture value PV1 after cooling or the actual moisture value PV2 after baking changes too quickly and the above ① and ② situations do not exist, that is, when the data deviates from the center value for N1 seconds, the following formula is used: ⅰ If only the actual moisture value PV1 after cooling changes too fast, the moisture correction value X satisfies the following formula: X=CV1*(a-y3)+CV2*(b+y3)(17); y3=A2*k3=(PV2-SP2)*k3(18); Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y3 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after cooling; k3 is the correction coefficient when moisture data after cooling changes too fast; If a-y3<0, that is, the weight of (a-y3) is less than 0, then y3 is assigned a, then a-y3=aa=0, b+y3=a+b=1, at this time, CV1 is not required for feedback, and X is fully fed back by CV2, then formula (17) is simplified to: X=CV2(14) ⅱIf only the actual value PV2 of moisture after drying changes too fast, then: X=CV1*(a+y4)+CV2*(b-y4)(19); y4=A1*k4=(PV1-SP1)*k4(20); Where a+b=1, 0≤a≤1, 0≤b≤1; CV1 is the moisture correction value after cooling; CV2 is the moisture correction value after baking; A2 is the moisture deviation value after baking; a is the weight coefficient of moisture participation feedback after cooling; b is the weight of moisture participation feedback after baking; y4 is the correction value of the weight coefficient due to the effect of too fast change of moisture data after baking; k4 is the correction coefficient when moisture data after baking changes too fast; If b-y4<0, that is, the weight of (b-y4) is less than 0, then y4 is assigned to b, then b-y4=bb=0, a+y4=a+b=1, at this time, CV2 is not required for feedback, and X is fully fed back by CV1, then formula (19) is simplified to: X = CV1(11); ⅲ When the actual value of moisture after cooling PV1 and the actual value of moisture after baking PV2 change too fast at the same time, then: X = CV1(11); The excessive change of the actual moisture value PV1 after cooling or the actual moisture value PV2 after baking is defined as the sum of the change values ​​of N2 cycles being greater than or equal to the threshold G2, and the formula is expressed as:

2. A control system, characterized in that: It includes a wire drying machine, a cooling and air separation device, a moisture PID controller after cooling, a moisture PID controller after drying, and a wire drying machine control unit; The inlet of the silk drying machine is connected to the outlet of the moisture conditioning machine, and a moisture meter after drying is installed at the outlet of the silk drying machine's discharging vibration conveyor, which is used to measure the moisture after drying at the outlet of the silk drying machine's discharging vibration conveyor; The cooling air selection device is arranged downstream of the tobacco drying machine, the inlet of the cooling air selection device is connected to the outlet of the tobacco drying machine, the outlet of the cooling air selection device is connected to the post-process of the tobacco production line, and the outlet of the cooling air selection device is equipped with a post-cooling moisture meter for measuring the post-cooling moisture at the outlet of the cooling air selection device; The post-cooling moisture PID controller is connected to the post-cooling moisture meter and the wire drying machine control unit. The post-cooling moisture PID controller calculates the post-cooling moisture actual value PV1 as the process value and the post-cooling moisture standard value SP1 as the set value, and transmits the calculated post-cooling moisture correction value CV1 to the wire drying machine control unit. The post-drying moisture PID controller is connected to the post-drying moisture meter and the wire drying machine control unit. The post-drying moisture PID controller calculates the post-drying moisture actual value PV2 as the process value and the post-drying moisture standard value SP1 as the set value, and transmits the calculated post-drying moisture correction value CV2 to the wire drying machine control unit. The wire drying machine control unit is connected to the moisture after cooling PID controller, the moisture after drying PID controller and the wire drying machine, and is used to calculate the moisture correction value X by the moisture correction value selection rule of the moisture after cooling CV1 and the moisture after drying CV2. The moisture correction value X is transmitted to the wire drying machine as the final feedback data to control the moisture at the outlet of the wire drying machine.

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