A control system and usage method for solid material level

Abstract

The present invention belongs to the technical field of pyrolysis, and particularly relates to a control system and a usage method for the solid material level. A control system for the solid material level includes a silo, a level switch, and a system core controller. The system core controller PLC is responsible for receiving signal inputs, calculating the output opening of the discharging mechanism through a control algorithm according to the input signals, and outputting the result to the discharging mechanism to achieve the level loop control; the signal inputs it receives include: the level measurement signal measured by the level switch, the opening feedback of the feeding mechanism, and the opening feedback of the discharging mechanism. The technical solution of the present invention first ensures the safety of the high-high level HH and the low-low level LL of the material level; secondly, the level control can adapt to the influence of the feeding mechanism on the material level; thirdly, the stable control of the material level is achieved, and the fluctuation range is between the high level H and the low level L, so that the system reaches a stable equilibrium state.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste pyrolysis, and particularly relates to a control system and a usage method for the solid material level. Background Art

[0002] The high-temperature flue gas carries the heat carrier and passes through the cyclone. The high-temperature flue gas is discharged upward through the flue, and the solid high-temperature particulate heat carrier falls downward into the silo. If the material level in the silo is too full, it will accumulate in the cyclone cavity, affecting the separation efficiency of the heat carrier, losing the heat carrier, and blocking the flue. If the material level in the silo is too low or emptied, the dynamic material seal between the silo and the reactor will not meet the requirements, which may cause the pyrolysis gas to leak into the flue and result in a safety accident. Therefore, maintaining the material level is crucial. Since the heat carrier enters from the top and exits from the bottom in the silo, this dynamic material seal only needs to be maintained within a calculated range that is neither too high nor too low, and does not need to be stabilized at a certain position point.

[0003] In the material level measurement technology, continuous material level measurement is usually used for good working conditions: normal temperature medium, less dust, suitable container shape, loose sealing requirements, etc. Radar, ultrasonic wave, etc. in this type of technology can no longer measure the material level of the heat carrier due to the harsh working conditions. Discrete material level measurement is usually an interval measurement method applied when the accuracy requirements for the material level are not high or the working conditions are extremely harsh and continuous measurement cannot be achieved by the current measurement technology level, that is, the material level is measured through a level switch, and the measurement signal is a switch quantity signal, and the presence or absence data of the material level is read.

[0004] Discrete material level control belongs to fuzzy control. The effects of feeding and discharging control cannot be reflected in real time. On the premise of ensuring that the material level reaches a certain level, quantitative measurement of the feeding amount and discharging amount, as well as fuzzy stable control of the material level, cannot be achieved. The control of the material level cannot be achieved through traditional classical control methods or PID control. Therefore, it is necessary to invent an advanced control logic method to achieve stable control of discrete material level fuzzy measurement. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a control device for the solid material level in high-temperature and high-dust working conditions, so as to solve the lag, reliability, and safety of the material level control of the solid particle silo under complex, high-temperature, and high-risk working conditions.

[0006] To achieve this purpose, the technical solution adopted by the present invention is:

[0007] A control system for the solid material level includes a silo, a level switch, and a system core controller PLC.

[0008] I. System Core Controller PLC

[0009] The system core controller PLC is responsible for receiving signal inputs, calculating the output opening of the discharging mechanism according to the input signals through control algorithms, and outputting to the discharging mechanism to achieve the control of the material level loop; the signal inputs it receives include: the material level measurement signal obtained by the material level switch, the opening feedback signal of the feeding mechanism, and the opening feedback signal of the discharging mechanism.

[0010] II. Silo

[0011] The silo is of a vertical structure, and the solid particle medium flows downward by its own gravity.

[0012] III. Material Level Switch

[0013] N material level switches are arranged in sequence from top to bottom in the silo to monitor the silo material level.

[0014] Furthermore, for a control device for the solid silo material level as described above, the system core controller PLC is connected to the material level switch to monitor and control it.

[0015] Furthermore, for a control device for the solid silo material level as described above, the height spacing between two adjacent material level switches satisfies the following condition: ensuring that the response time required for the adjustment of feeding and discharging is greater than 15 s.

[0016] Furthermore, for a control device for the solid silo material level as described above, the number N of the material level switches is N≥4.

[0017] Furthermore, for a control device for the solid silo material level as described above, the first material level switch, the second material level switch, the third material level switch, and the fourth material level switch are arranged in sequence from top to bottom in the silo, and the above four material level switches respectively measure the high-high material level signal, the high-high material level signal, the low material level signal, and the low-low material level signal.

[0018] Furthermore, for a control device for the solid silo material level as described above, the heights of the first material level switch, the second material level switch, the third material level switch, and the fourth material level switch decrease in sequence.

[0019] Furthermore, for a method of using a control device for the solid silo material level as described above, it is characterized in that:

[0020] N material level switches are arranged in sequence from top to bottom in the silo to monitor the silo material level, and the silo material level monitored by the material level switch has the following characteristics:

[0021] The highest material level is marked as HH, the lowest material level is marked as LL, and the interval between the highest material level HH and the lowest material level LL is the safe material level interval of the silo;

[0022] The number of intermediate material levels ≥ 2, including: a high material level marked as H, a low material level marked as L, and other material levels between the high material level H and the low material level L; the range between the intermediate material levels is the target range for silo control.

[0023] The material level control is carried out according to the following steps:

[0024] (1) Safety control of the silo material level

[0025] (1A) When the material level measured by the level switch corresponding to the highest material level mark shows a high-high level signal and exceeds the system-set safety time range T1, the discharge mechanism outputs fully open to an opening of 100%;

[0026] (1B) When the material level measured by the level switch corresponding to the lowest material level mark shows a low-low level signal and exceeds the system-set safety time range T2, the discharge mechanism outputs closed to an opening of 0%;

[0027] (2) Reference control of the silo material level

[0028] Set a control target reference matrix. By means of matrix query, the influence of the feeding mechanism on the material level is offset in advance through the actions of the discharge mechanism;

[0029] (2A) The abscissa of the matrix is the control output value of the feeding mechanism, with a range of 0% to 100%;

[0030] (2B) The ordinate is the control output reference value of the discharge mechanism, marked as W%, with a range of 0% to 100%;

[0031] (2C) When the silo material level is between the high material level H and the low material level L and exceeds the system-set dynamic stability time T3, the control output reference value of the discharge mechanism in step (2B) is output to the discharge mechanism;

[0032] (3) Low material level control of the silo material level

[0033] When the material level shows n signals lower than the low material level L, sorted by height as L1 > L2 > … > Ln, and marked as low L1 signal, low L2 signal … low Ln signal respectively;

[0034] When the material level shows a low L1 signal and reaches the system-set time TL1, the control output value of the discharge mechanism will automatically reduce the control output of the discharge mechanism by S1% based on the control output reference value of the discharge mechanism. Each time the TL1 time is reached, the output is automatically reduced by S1%;

[0035] When the low L2 signal... low Ln signal appears in the material level and reaches the system-set time TL2... TLn, the control output value of the discharging mechanism will automatically decrease by S2%... Sn% on the basis of the control output reference value of the discharging mechanism. Every time the system-set time TL2... TLn is reached, the control output value of the discharging mechanism will automatically decrease by S2%... Sn% on the basis of the control output reference value of the discharging mechanism;

[0036] The times TL1... TLn are set according to the system characteristics, and S1 < S2... < Sx;

[0037] When the material level is adjusted between the high level H and the low level L, step (2) is executed;

[0038] (3) High-level control of the silo material level

[0039] When m signals higher than the high level H appear in the material level, they are sorted by height as H1 < H2 <... < Hm and are respectively marked as high H1 signal, high H2 signal... high Hm signal;

[0040] When the high H1 signal appears in the material level and reaches the system-set time TH1, the control output value of the discharging mechanism will automatically increase by J1% on the basis of the control output reference value of the discharging mechanism. Every time the time TH1 is reached, the control output value of the discharging mechanism will automatically increase by J1% on the basis of the control output reference value of the discharging mechanism;

[0041] When the high H2 signal... high Hm signal appears in the material level and reaches the system-set time TH2... THm, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism. Every time the system-set time TH2... THm is reached, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism;

[0042] The times TH1... THm are set according to the system characteristics, and J1 < J2... < Jx;

[0043] When the material level is adjusted between the high level H and the low level L, step (2) is executed.

[0044] The beneficial effects of the technical solution of the present invention are as follows: The technical solution of the present invention includes a silo, level switches at high-high, high, low, and low-low positions, a discharging mechanism and a controller, and a core control system. First, when the control system receives high-high HH or low-low LL signals, the control system adjusts and checks according to time, and monotonically increases or decreases the controller of the discharging mechanism to make the level return to between the normal high and low, avoiding the safety problems caused by the oscillation of conventional control. Second, the level control can adapt to the influence of the feeding mechanism on the level. Third, the control system realizes stable control of the level, not precise control at a certain reference point, but fluctuates between the high level H and the low level L, slowing down the fluctuation and oscillation of the control system, and being more conducive to the stable and reliable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Appendix Figure 1 It is a schematic structural diagram of a control device for the level of a solid silo.

[0046] In the figure: 1 silo, 2 core system controller PLC, 301 first level switch, 302 second level switch, 303 third level switch, 304 fourth level switch, 4 discharging mechanism. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solution of the present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0048] As Figure 1 shown, the control objective of the technical solution of the present invention is the control of the level of a solid silo, and the specific control objectives are as follows:

[0049] 1) The level control ensures that there is always material at the lowest level, ensuring the safety of the level control;

[0050] 2) The level control is maximally maintained between the intermediate measured levels, achieving the stability of the level control;

[0051] 3) The level is at the lowest degree lower than the highest level, avoiding affecting other systems;

[0052] 4) When the level is within the stable range, the feeding and discharging system is in a dynamic balance state of stable operation.

[0053] In the technical solution of the present invention, the silo 1 is of a vertical structure, and the solid particle medium flows downward by its own gravity. The level of the silo cannot be measured by a continuous measurement method; the feeding and discharging actuator is of a continuous adjustment control type, the feeding mechanism has a certain lag and no controllability, and the discharging mechanism 4 has no lag, and the level control is achieved by adjusting the discharging mechanism 4.

[0054] The system core controller PLC2 is responsible for receiving signal inputs, connecting with the level switches, monitoring and controlling them. Based on the input signals, it calculates the output opening of the discharging mechanism through a control algorithm and outputs it to the discharging mechanism to achieve the level loop control; the signal inputs it receives include: the level measurement signal obtained by the level switch measurement, the opening feedback of the feeding mechanism, and the opening feedback of the discharging mechanism.

[0055] N level switches are arranged in the silo 1 from top to bottom in sequence for monitoring the silo level, where N≥4. The height spacing between two adjacent level switches meets the following conditions: ensuring that the response time required for the feeding and discharging adjustment is greater than 15s.

[0056] Based on the usage method of a control device for the solid silo level described above, N level switches are arranged in the silo from top to bottom in sequence for monitoring the silo level, and the silo level monitored by the level switch has the following characteristics:

[0057] The highest level is marked as HH, the lowest level is marked as LL, and the interval between the highest level HH and the lowest level LL is the safe level interval of the silo;

[0058] The number of intermediate levels ≥2, including: the high level marked as H, the low level marked as L, and other levels between the high level H and the low level L; the interval between the intermediate levels is the target range for silo control.

[0059] Since the feeding mechanism has a certain hysteresis and is not controlled by the level, the only actuator for level control is the discharging mechanism 4. Based on the above analysis, the level control is carried out according to the following steps:

[0060] (1) Safety control of the silo level

[0061] (1A) When the level measured by the level switch corresponding to the highest level mark shows a high-high level signal and exceeds the system-set safe time range T1, the discharging mechanism outputs fully open to an opening of 100%;

[0062] (1B) When the level measured by the level switch corresponding to the lowest level mark shows a low-low level signal and exceeds the system-set safe time range T2, the discharging mechanism outputs closed to an opening of 0%;

[0063] Step (1) has the highest priority in the process of level control.

[0064] (2) Reference control of the silo level

[0065] Set the control target reference matrix, and through the method of matrix query, offset the influence of the feeding mechanism on the level in advance through the action of the discharging mechanism;

[0066] (2A) The abscissa of the matrix is the control output value of the feeding mechanism, with a range of 0% to 100%;

[0067] (2B) The ordinate is the control output reference value of the discharging mechanism, marked as W%, with a range of 0% to 100%;

[0068] (2C) When the material level in the silo is between the high level H and the low level L and exceeds the system-set dynamic stability time T3, the control output reference value of the discharging mechanism in step (2B) is output to the discharging mechanism;

[0069] (3) Low-level control of the material level in the silo

[0070] When n signals indicating that the material level is lower than the low level L appear, sorted by height as L1 > L2 >... > Ln, they are respectively marked as low L1 signal, low L2 signal... low Ln signal;

[0071] When the low L1 signal appears at the material level and reaches the system-set time TL1, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S1% based on the control output reference value of the discharging mechanism. Each time the TL1 time is reached, the output will automatically reduce by S1%;

[0072] When the low L2 signal... low Ln signal appear at the material level and reach the system-set time TL2... TLn, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S2%... Sn% based on the control output reference value of the discharging mechanism. Each time the system-set time TL2... TLn is reached, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S2%... Sn% based on the control output reference value of the discharging mechanism;

[0073] The times TL1... TLn are set according to the system characteristics, and S1 < S2... < Sx;

[0074] When the material level is adjusted between the high level H and the low level L, step (2) is executed;

[0075] (4) High-level control of the material level in the silo

[0076] When m signals indicating that the material level is higher than the high level H appear, sorted by height as H1 < H2 <... < Hm, they are respectively marked as high H1 signal, high H2 signal... high Hm signal;

[0077] When the high H1 signal appears at the material level and reaches the system-set time TH1, the control output value of the discharging mechanism will automatically increase the output of the discharging mechanism by J1% based on the control output reference value of the discharging mechanism. Each time the TH1 time is reached, the control output value of the discharging mechanism will automatically increase the output of the discharging mechanism by J1% based on the control output reference value of the discharging mechanism;

[0078] When the high H2 signal... high Hm signal appears at the material level and reaches the system-set time TH2... THm, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism. Each time the system-set time TH2... THm is reached, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism;

[0079] The times TH1... THm are set according to the system characteristics, and J1 < J2... < Jx;

[0080] When the material level is adjusted between the high material level H and the low material level L, step (2) is executed.

[0081] In this embodiment, as Figure 1 shown, a first level switch 301, a second level switch 302, a third level switch 303, and a fourth level switch 304 are sequentially arranged from top to bottom in the silo 1. The above four level switches respectively measure the high-high level signal, the high-high level signal, the low level signal, and the low-low level signal of the material level.

[0082] On the basis of the above technical solution, the specific process of material level control specifically includes the following four situations:

[0083] When the material level is high-high, that is, the first level switch 301, the second level switch 302, the third level switch 303, and the fourth level switch 304 all detect the material level signal; when it is low-low, that is, the first level switch 301, the second level switch 302, the third level switch 303, and the fourth level switch 304 all do not detect the material level signal;

[0084] At this time, a safety action is executed. When it is high-high, the discharging mechanism 4 is fully opened, and when it is low-low, the discharging mechanism is fully closed. This situation has the highest control priority.

[0085] When the material level is high, that is, the first level switch 301 has no signal, and the second level switch 302, the third level switch 303, and the fourth level switch 304 all detect the material level signal. At this time, the control method is to continuously detect the material level, and after every time interval of 8 s, the opening of the discharging mechanism 4 is automatically cycled and increased. Each time the opening is increased by 2%, until the material level is maintained between high and low, that is, the first level switch 301 and the second level switch 302 have no signal, and the third level switch 303 and the fourth level switch 304 have the material level signal. After 60 s, the output value of the discharging mechanism is automatically given by the system core controller PLC 2.

[0086] When the material level is low, that is, there is no signal from the 301 first material level switch, 302 second material level switch, and 303 third material level switch, and the 304 fourth material level switch detects the material level signal. At this time, the control mode is to continuously detect the material level, and after every 8s time interval, automatically and cyclically reduce the opening of the discharging mechanism 4 by 2% each time until the material level is maintained between high and low, that is, there is no signal from the 301 first material level switch and 302 second material level switch, and there is a material level signal from the 303 third material level switch and 304 fourth material level switch. After 60s, the output value of the discharging mechanism 4 is automatically given by the system core controller PLC.

[0087] When the material level is between high and low, that is, there is no signal from the 301 first material level switch and 302 second material level switch, and there is a material level signal from the 303 third material level switch and 304 fourth material level switch. At this time, the control mode is to continuously detect the material level, and the output value of the discharging mechanism 4 is automatically given by the system core controller PLC 2 to control the stable operation of the discharging mechanism 4.

Claims

1. A method for controlling the level of a solid silo, characterized in that: N level switches are arranged in sequence from top to bottom in the silo (1) to monitor the level of the silo, and the levels of the silo monitored by the level switches have the following characteristics: The highest level is marked as HH, the lowest level is marked as LL, and the interval between the highest level HH and the lowest level LL is the safe level interval of the silo; The number of intermediate levels ≥ 2, including: a high level marked as H, a low level marked as L, and other levels between the high level H and the low level L; the interval between the intermediate levels is the target range for silo control; The level control is carried out according to the following steps: (1) Safety control of the silo level (1A) When the level measured by the level switch corresponding to the highest level mark shows a high-high level signal and exceeds the system-set safety time range T1, the output of the discharging mechanism is fully opened to an opening of 100%; (1B) When the level measured by the level switch corresponding to the lowest level mark shows a low-low level signal and exceeds the system-set safety time range T2, the output of the discharging mechanism is closed to an opening of 0%; (2) Reference control of the silo level Set a control target reference matrix, and through matrix query, offset the influence of the feeding mechanism on the level in advance through the action of the discharging mechanism; (2A) The abscissa of the matrix is the control output value of the feeding mechanism, with a range of 0% to 100%; (2B) The ordinate is the control output reference value of the discharging mechanism, marked as W%, with a range of 0% to 100%; (2C) When the silo level is between the high level H and the low level L and exceeds the system-set dynamic stability time T3, output the control output reference value of the discharging mechanism in step (2B) to the discharging mechanism; (3) Low-level control of the silo level When n signals indicating that the level is lower than the low level L appear, sorted by height as L1 > L2 >... > Ln, and marked as low L1 signal, low L2 signal... low Ln signal respectively; When the low L1 signal appears and reaches the system-set time TL1, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S1% based on the control output reference value of the discharging mechanism, and each time the time TL1 is reached, the output will automatically reduce by S1%; When the low L2 signal... low Ln signal appears and reaches the system-set time TL2... TLn, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S2%... Sn% based on the control output reference value of the discharging mechanism, and each time the system-set time TL2... TLn is reached, the control output value of the discharging mechanism will automatically reduce the output of the discharging mechanism by S2%... Sn% based on the control output reference value of the discharging mechanism; The times TL1... TLn are set according to the system characteristics, and S1 < S2... < Sx; When the level is adjusted between the high level H and the low level L, execute step (2); (3) High-level control of the silo level When m signals indicating that the level is higher than the high level H appear, sorted by height as H1 < H2 <... < Hm, and marked as high H1 signal, high H2 signal... high Hm signal respectively; When the high level H1 signal appears in the material level and reaches the system-set time TH1, the control output value of the discharging mechanism will automatically increase by J1% on the basis of the control output reference value of the discharging mechanism. Every time the time TH1 is reached, the control output value of the discharging mechanism will automatically increase by J1% on the basis of the control output reference value of the discharging mechanism. When the high level H2 signal... high level Hm signals appear in the material level and reach the system-set times TH2... THm, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism. Every time the system-set times TH2... THm are reached, the control output value of the discharging mechanism will automatically increase by J2%... Jm% on the basis of the control output reference value of the discharging mechanism. The times TH1... THm are set according to the system characteristics, and J1 < J2... < Jx. When the material level is adjusted between the high level H and the low level L, step (2) is executed.

2. A solid material bin material level control system based on the control method of the solid material bin material level as described in claim 1, characterized in that: It includes a material bin (1), a material level switch, and a system core controller PLC (2); I. System core controller PLC (2) The system core controller PLC (2) is responsible for receiving signal inputs, calculating the output opening of the discharging mechanism through a control algorithm according to the input signals, and outputting to the discharging mechanism to achieve material level loop control; the signal inputs it receives include: the material level measurement signal measured by the material level switch, the opening feedback signal of the feeding mechanism, and the opening feedback signal of the discharging mechanism. II. Material bin (1) The material bin (1) is of a vertical structure, and the solid particle medium flows downward by its own gravity. III. Material level switch N material level switches are sequentially arranged from top to bottom in the material bin (1) to monitor the material level of the material bin.

3. A solid material bin material level control device as described in claim 2, characterized in that: The system core controller PLC (2) is connected to the material level switch to monitor and control it.

4. A solid material bin material level control device as described in claim 2, characterized in that: The height spacing between two adjacent material level switches satisfies the following condition: ensuring that the response time required for feeding and discharging adjustment is greater than 15 s.

5. A solid material bin material level control device as described in claim 2, characterized in that: The number N of the material level switches ≥ 4.

6. A solid material bin material level control device as described in claim 2, characterized in that: The number N of the material level switches = 4.

7. A solid material bin material level control device as described in claim 2, characterized in that: A first material level switch (301), a second material level switch (302), a third material level switch (303), and a fourth material level switch (304) are sequentially arranged from top to bottom in the material bin, and the above four material level switches respectively measure the high-high material level signal, the high-high material level signal, the low material level signal, and the low-low material level signal.

8. A solid material bin material level control device as described in claim 2, characterized in that: The heights of the first level switch (301), the second level switch (302), the third level switch (303), and the fourth level switch (304) decrease in sequence.

9. A control device for the level of a solid silo as described in claim 3, characterized in that: The system core controller PLC (2) is connected to the level switches for monitoring and control thereof; the height spacing between two adjacent level switches meets the following condition: ensuring that the response time required for the adjustment of material feeding and discharging is greater than 15 s; the number of level switches N = 4; the first level switch (301), the second level switch (302), the third level switch (303), and the fourth level switch (304) are arranged in sequence from top to bottom in the silo, and the above four level switches respectively measure high-high level signals, high-high level signals, low level signals, and low-low level signals; the heights of the first level switch (301), the second level switch (302), the third level switch (303), and the fourth level switch (304) decrease in sequence.

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