Method for controlling a sintering machine, related controller and sintering machine

Abstract

The present invention relates in particular to a method for controlling a sintering machine (1) comprising a belt conveyor, the method comprising: - acquiring the windbox temperatures (WBT i ) in several successive windboxes (WB i ) arranged below the belt (2) of the conveyor; - determining a temperature rise slope from at least some of said windbox temperatures, said temperature rise slope representing the slope of the temperature as a function of the position along the belt of the conveyor, upstream of the position of the highest temperature; - controlling the speed of the belt of the conveyor as a function of said temperature rise slope.

Description

Technical Field

[0001] This technical field belongs to ore sintering, particularly iron ore sintering. More specifically, it relates to the control and adjustment technology of sintering machines, which include belt conveyors and forced ventilation systems. Background Technology

[0002] Sintering machines used for sintering materials such as iron ore typically consist of a belt conveyor with an endless belt for transporting the material. This belt has a grate-like structure to allow airflow over the material arranged on the belt. Adjacent bellows are arranged below the belt along the conveyor to draw air through the material. As the sintering machine operates, the material layer is ignited at one end of the conveyor, and as the material is displaced by the belt, the height to which the material is sintered gradually increases until it is sintered across its entire height. The point where the material is sintered across its entire height is called the through-thickness point (also referred to as BTP below).

[0003] Some bellows can be equipped with temperature sensors to measure the temperature of the gas (mainly air) being drawn through the material. The point along the belt where this gas temperature reaches its maximum is designated as the BTP (Bottom Point Tolerance). Therefore, the location of the BTP can be derived from the bellows temperature measurements. The belt speed can then be controlled so that the BTP is equal to a given setpoint. In practice, this setpoint is typically chosen near the conveyor's discharge end. In practice, the conveyor length is usually chosen to be just greater than the length required for complete sintering (to avoid constructing an unnecessarily long conveyor).

[0004] Another method for controlling and regulating the operation of the sintering machine is to adjust the belt speed so that the temperature of the exhaust gas is equal to a given set temperature.

[0005] Regardless, controlling and regulating the operation of a sintering machine is inherently challenging. In reality, as the material is moved by the conveyor, initially, over a considerable distance (typically about half or more of the total conveyor length), the temperature of the gas being drawn through changes very little, and there is no direct way to monitor how the process evolves. Then, at the end of the conveyor, the temperature rises very rapidly. Therefore, regulating such a process involves both significant time lags and a certain degree of abruptness in the process. Furthermore, it is preferable that the position of the BTP must be adjusted close to its maximum acceptable limit (i.e., close to the discharge end of the conveyor), which is inconvenient for automation.

[0006] Against this backdrop, document EP2737094 describes a method for controlling and adjusting the position of the BTP, even when the position is outside the conveyor area equipped with a temperature sensor. However, the efficiency of this control method is still limited by the aforementioned time lag effect, and because other parameters used for monitoring the process (such as the temperature of the burn-through point) are not considered when adjusting the conveyor speed. Summary of the Invention

[0007] In this context, a method for controlling a sintering machine according to claim 1 is provided.

[0008] In particular, compared with the main basis of the burn-through point location This control method is advantageous compared to existing techniques for controlling belt speed.

[0009] In fact, upstream of BTP, the temperature rise slope :

[0010] - It provides more information than just the location of the BTP (because the slope reflects the location and temperature of the BTP, as well as the location and temperature upstream of the BTP where the temperature begins to rise), and provides this information in a concise, comprehensive form (which is well-suited as a controller input).

[0011] - It achieves better predictions than using the location or temperature of BTP because it depends on the temperature upstream of BTP (and in terms of time, it depends on what happened before BTP) and represents the dynamics of the material sintering process in the critical region upstream of BTP.

[0012] The method according to this technology may include one or more additional features, individually or in combination, as defined in claims 2 to 16.

[0013] This technology also relates to the electronic control unit as defined in claim 17 and the sintering machine as defined in claim 18.

[0014] This technology also relates to a computer program comprising instructions that, when executed on a computer (possibly connected to suitable sensors and actuators), cause the computer to perform the steps of the methods described above. This technology also relates to a non-transitory computer-readable medium (e.g., a hard disk, USB flash drive, or other flash memory) including such a computer program. Attached Figure Description

[0015] The technology will now be described in more detail with reference to the accompanying drawings and illustrated by examples, without introducing any limitations.

[0016] Figure 1 This is a schematic side view of a sintering machine.

[0017] Figure 2 In order to control the machine, by Figure 1 A schematic block diagram of the different control loops implemented by the electronic control unit of the sintering machine.

[0018] Figure 3 It schematically shows that in Figure 1 The standard deviation of the temperature measured in a specific airbox of the sintering machine, and the value of the relevant correction factor used to correct that temperature before using it to adjust the sintering machine.

[0019] Figure 4 The values ​​of the bellows temperature as a function of the position x of the belt along the sintering machine conveyor are schematically shown, as well as the curve fitting of these temperatures that enables the determination of the burn-through point location.

[0020] Figure 5 The value of the bellows temperature as a function of position x is schematically shown, along with the corresponding temperature rise slope and temperature rise slope setpoint.

[0021] Figure 6 The histograms of sintering temperatures are schematically shown when the sintering machine is controlled by its electronic control unit and when it is directly manually controlled by the operator. Detailed Implementation

[0022] Sintering machine

[0023] Figure 1 A sintering machine 1 for sintering materials M such as iron ore is schematically shown. The sintering machine 1 includes a belt conveyor with an endless belt 2 for conveying material M from a loading end 21 to a discharging end 22 of the conveyor, wherein the material is loaded onto the belt by hoppers 5 (possibly using a loading rotary cylinder). The belt 2 has a grate-like structure to allow airflow over the material M arranged on the belt. The belt 2 can be formed as a single continuous belt, or it can be formed by several consecutive trolleys connected (in an articulated manner) to each other. The belt conveyor extends from its loading end 21 to its discharging end 22 along a longitudinal axis x (from the loading end to the discharging end). The movement of the belt 2 is guided at each end 21, 22 by one or more rotating shafts. The belt 2 is continuously moved in the direction of the axis x by an actuator 3 (e.g., an electric motor mechanically coupled to one of the rotating shafts).

[0024] bellows WB1, WB2, ..., WB 23 Arranged below the conveyor belt 2, bellows are used to draw gas (actually a mixture of air and combustion gases) through the material M disposed on it. Bellows are arranged one after another along axis x. Their respective openings are adjacent to each other (and may even be continuous). The first bellows WB1 is located near the loading end 21 of the conveyor, while the last bellows WB... 23Located near its discharge end 22. One of the first bellows, here the first bellows WB1, is located directly below the ignition shroud 4 used to ignite the material M. Figure 1 In the example, sintering machine 1 has 23 bellows WB1–WB 23 However, the number of bellows can vary. It is typically 10 to 40. Here, each bellows is fluidly connected to a common suction pipe 6, which is equipped with an exhaust fan 8 at its output end. When the exhaust fan 8 is running, air is drawn through the material M by the bellows, thus creating forced draft, which is beneficial for the gradual ignition and sintering of the material M.

[0025] Sintering machine 1 is equipped with several sensors.

[0026] First, at least some bellows are each equipped with one or more temperature sensors. In this example, all bellows are each equipped with one temperature sensor (not shown in the figure), except for the last three bellows, each equipped with two temperature sensors, one on the left side of the belt and the other on its right side (left and right relative to the central longitudinal axis of the belt extending from the loading end to the unloading end). Each of these sensors is arranged to measure the temperature of the gas drawn through the material M layer by the bellows. The temperature measured by these sensors is referred to below as the bellows temperature. For bellows WB i (The exponent i ranges from 1 to N, representing the number of the bellows under consideration, where N is the total number of bellows, which is 23 in this case.) The corresponding bellows temperature is expressed as WBT. i For bellows equipped with two temperature sensors (left and right), WBT i It is the average of the temperature measurements on the left and right sides (where the left and right measurements are respectively expressed as WBT). il and WBT ir In an alternative implementation, each bellows may include only one temperature sensor (or conversely, they may all be equipped with two, i.e., left and right temperature sensors).

[0027] In this embodiment, another temperature sensor 7 is located in the suction duct 6 or at the output of the exhaust fan 8. It measures the exhaust gas temperature WGT, which represents the temperature of the overall mixed gas discharged from the different air boxes.

[0028] The sintering machine 1 may also include a pressure sensor (not shown in the figure) arranged in a bellows located below the ignition shroud 4, as well as other possible sensors, such as a height measuring device for measuring the height of the material layer arranged on the belt, or a flow meter or other type of sensor for estimating the total flow through the ignition shroud 4.

[0029] When the sintering machine is running, the height to which the material is sintered gradually increases during the displacement of material M along the x-axis until the material is sintered across its entire height. The point where the material is sintered across its entire height is called the burn-through point (BTP). Figure 1 In the diagram, sintered materials (i.e., sintered ore) are represented in dark gray, while unsintered materials are represented in light gray.

[0030] The temperature of the gas being drawn through the material layer M varies along the x-axis as follows: Initially, over a considerable distance (approximately half or more of the total conveyor length), the temperature change is minimal. Then it begins to increase significantly (at a point known as the temperature rise point TRP) and reaches its maximum at the burn-through point BTP. Subsequently, downstream of the burn-through point (i.e., after BTP, in the direction of the discharge end), the temperature decreases. This temperature variation of the gas being drawn through the material layer M is reflected in the bellows temperature, which is sampled at various locations along the x-axis in a manner consistent with the temperature of the bellows.

[0031] The sintering machine 1 also includes an electronic control unit 10, which is operatively connected to the temperature sensor of the bellows and may also be connected to the other sensors mentioned above. The control unit 10 is also connected to the actuator 3 driving the belt and is configured to control the belt speed v via the actuator 3. The control unit 10 is an electronic device including logic circuitry and possibly analog circuitry, arranged to implement a control loop for regulating the belt speed v. For example, it may take the form of a programmable corrector or an electronic card including a Field Programmable Gate Array (FPGA) chip. The control unit 10 may have a computer architecture. The control unit 10 is configured to implement the control methods described below.

[0032] Control methods

[0033] It is worth noting that the method includes:

[0034] - Obtain at least some bellows temperature WBT i (Preferably, the air box temperature near the BTP at the end of the conveyor), which is all of them here.

[0035] - Determined by at least some bellows temperature WBT i Determine the temperature rise slope The slope of the temperature rise This indicates the location of the highest temperature. Upstream of (the location of the burn-through point BTP), the slope of the temperature (of the gas being drawn through the material) as a function of the position x along the conveyor belt 2.

[0036] - Based on the temperature rise slope and temperature rise slope setpoint The speed v of belt 2 of the control conveyor, and the set value of the temperature rise slope. The control unit 10 automatically calculates the values ​​based on the measured and setpoint values ​​of the BTP. Figure 2 and Figure 4 ).

[0037] As described in the "Summary of the Invention" section, especially in relation to [the invention] primarily based on the location of the burn-through point. This control method is advantageous compared to existing techniques for controlling belt speed.

[0038] More specifically, in this exemplary embodiment, the belt speed v uses three different control loops 11, 12, and 13 ( Figure 2 The control loop 11 is controlled by selection logic 14, which switches between these loops (depending on specific conditions) and another loop. The control loop 11 is referred to as the stabilization loop and is configured primarily based on the temperature rise slope. To control v. Control loop 12 is called a correction loop and is configured to control v primarily based on the temperature of the gas being drawn through the material layer, which is measured at various locations (e.g., in different bellows and in the suction pipe 6). Control loop 13 is called a protection loop and is configured primarily based on the burn-through point location. To control v. Here, each control loop 11, 12, or 13 is a PID control loop (i.e., proportional, integral, and derivative control loop). However, it can be noted that in such PID control loops, the derivative (or even integral) corrector can be omitted, and the P, I, and D correctors can be arranged in series or parallel. Furthermore, in alternative embodiments, for these control loops, other types of controllers besides PID controllers can be used.

[0039] For this application, it is advantageous to use more than one control loop to control the belt speed. In practice, there are two main types of actuators that can be controlled to regulate the sintering process: actuator 3 coupled to the conveyor belt and the exhaust fan 8 controlling forced draft, but the latter typically cannot achieve precise control. Therefore, primarily only one actuator can be used to regulate the sintering process, while it is desired to regulate several quantities (e.g., BTP position, BTP temperature, and other process parameters such as exhaust gas temperature), which may have different constraints and criteria. Then, using different control loops and associated selection logic makes it possible to effectively regulate these different quantities and address different constraints while controlling only one actuator (actuator 3).

[0040] Another complementary technique implemented here for regulating more than one quantity with only one actuator is to combine these quantities into a composite error signal and then use it in the control loop under consideration. In this regard, it should be noted that combining several quantities into a single error signal is not straightforward, because when controlling the actuator, these quantities must be selected so that they vary in the same manner.

[0041] Now, we will describe the selection logic 14 and control loops 11, 12, and 13 in more detail.

[0042] Selection Logic

[0043] Selection logic 14 is configured to select stable loop 11 by default. In other words, unless specific conditions are met (e.g., BTP location), If the value is higher than the maximum acceptable limit, then steady loop 11 is selected. In practice, steady loop 11 is the control loop selected most of the time.

[0044] Regarding protection circuit 13, when BTP position When the distance between the material discharge end 22 of the conveyor and the material discharge end 22 becomes less than a preset distance limit (in other words, when...) When it becomes higher than the corresponding maximum acceptable limit, it is selected (instead of the other two control loops 11 and 12).

[0045] Regarding correction circuit 12, when the exhaust gas temperature error signal WGT... cf er (Described in more detail below) When the allowable range is exceeded, it is selected (instead of the other two control loops 11 and 13). One purpose of the correction loop 12 is to adjust the speed v more aggressively than the stabilization loop 11 to maintain or correct the temperature when the temperature of the pumped gas deviates from the corresponding setpoint. Therefore, the corrector of the correction loop 12 is configured to have a higher correction gain and / or a shorter response time than the corrector of the stabilization loop 11.

[0046] The gain and / or response time of stabilization loop 11 are adjusted conservatively to improve stability. To slightly accelerate the adjustment of speed v when selecting stabilization loop 11, an optional supplementary signal (not shown in the figure) can be added to the output signal s of stabilization loop 11. 11 The supplementary signal is, for example, the time derivative of the bellows temperature, or the time derivative of the sum of the bellows temperatures.

[0047] Other components (not in) Figure 2 As shown in the diagram, these components are added to control loops 11, 12, and 13, such as tracking modules (for mutual tracking between different loops) to achieve seamless and smooth switching between different control loops.

[0048] Correction circuit

[0049] Correction loop 12 outputs control signal s 12 The control signal s 12 This is the setpoint for the conveyor belt speed v, and it is transmitted to actuator 3 (when correction loop 12 is selected by selection logic 14). Control signal s 12 This is generated by the PID corrector in correction loop 12, and its input is the error signal. . It is a set value, called the exhaust gas temperature set value (which may be related to more than just exhaust gas temperature). It can be preset and read from the instruction file during sintering machine operation. It can also be set by the operator during operation (and may be modified during operation). It depends at least on some temperature measured in the bellows (WBT). i The amount.

[0050] Here, The following quantities were combined:

[0051] - Depends on the selected bellows temperature WBT s The quantity is expressed as Here, More specifically, it depends on the selected bellows WB s Temperature deviation ,

[0052] - Exhaust gas temperature representing the overall exhaust gas temperature ; The temperature is measured by temperature sensor 7 (located in the suction pipe 6 or at the output of the exhaust fan 8).

[0053] - Material air permeability The estimated value was derived from the pressure measured in one of the bellows located below the ignition shield 4.

[0054] - Temperature at the point of complete burnout (where the gas is drawn in) (It is determined by some bellows temperature WBT) i (As explained below in the description of stable loop 11).

[0055] In order to obtain The signals are combined by adding the quantities mentioned above, according to the following formula F1:

[0056]

[0057] The sum of these amounts provides useful supplementary information about the sintering process. However, in other embodiments, in One or more of these quantities can be omitted. For example, You can only consider or only consider or even just considering Furthermore, the above sum can be a weighted sum, where the weighting coefficients are different from each other.

[0058] Selected bellows WB s This refers to the bellows located upstream of the BTP, for example, 3 to 10 bellows upstream of the BTP. Here, it is the bellows where the temperature begins to rise (temperature begins to increase with position x). The selected bellows WB s For example, the bellows where the temperature rise point TRP (described below) is located.

[0059] Here, according to the following formula F2, the deviation of the selected bellows temperature is... Multiply by (positive) correction factor c m To calculate :

[0060]

[0061] deviation For example, the selected bellows temperature WBT s With WBT s The difference between the (time) rolling averages.

[0062] It is worth noting that the correction factor c m Based on the selected bellows temperature WBT s The time fluctuation range (or similarly, representing) The time fluctuation (e.g., standard deviation) is used to determine this. m It can increase with the quantity stated (not necessarily continuously), as shown here (e.g., with the standard deviation).

[0063] Figure 3 Exemplary values ​​for the following items are shown:

[0064] - at continuous time step j ( Figure 3 At j=1..24), the selected wind box temperature WBT s standard deviation (Expressed in any unit); Standard deviation Each value is within the same (rolling) time window (which is the same as the calculation of WBT). s Calculated on the same rolling average.

[0065] - and the corresponding correction factor c m .

[0066] The duration of the time window discussed is related to machine size and typical process speed. For example, it includes 0.1 to 3 times the average time (typically several minutes) it takes to transport material from the loading end of the conveyor to the unloading end.

[0067] Here, the correction factor c m From standard deviation The following is confirmed:

[0068] - if If it is below a given threshold, then c m equal to zero, and

[0069] - if If it is higher than the threshold, then The higher, c m It keeps getting higher (e.g., c) m and It is proportional to the difference between the thresholds.

[0070] Correct the selected bellows temperature WBT using this correction factor. s (Or like here, its deviation) ), in error signal The selected bellows temperature is given greater importance when there are large fluctuations, thus enabling more effective stabilization of the bellows temperature compared to using uncorrected temperature values ​​(or compared to using correction factors independent of temperature fluctuations).

[0071] Regarding the air permeability of materials The estimated value, derived from pressure measurements in the bellows below ignition shroud 4, reflects the quality of the undisturbed material at the start of the conveyor. Therefore, it allows for the prediction of low-quality material arriving at the end of the conveyor. The determination of the quantity is described below. .

[0072] First, at regular time intervals, based on the gas pressure measured in the bellows located below the ignition shroud, the permeability of a portion of the material layer located below the ignition shroud is determined. For example, breathability can be determined using the following formula F3. :

[0073]

[0074] in:

[0075] - The pressure (relative to ambient pressure) is measured in the aforementioned bellows.

[0076] - It is the height of material layer M (for example, measured using the height measuring device mentioned above).

[0077] - It is the area of ​​the bellows opening that collects airflow below the ignition shield.

[0078] It is obtained by measuring the air (and / or gas) flow rate in the ignition shroud conduit (in the shroud's supply conduit, or at the bellows outlet).

[0079] More specifically, breathability The calculations can be performed based on the following article (Section 2.2 of which): 'Optimal mixing and granulation process for fine utilization in sinterplants' by Gergö Rimaszéki et al., ISSN 2176-3135, included in the proceedings of the 46th Seminário de Redução de Minério de Ferro eMatérias-primas, 17th Simpósio Brasileiro de Minério de Ferro e 4º SimpósioBrasileiro de Aglomeração de Minériode Ferro, part of the ABM Week, September 26th-30th, 2016. 2016, Rio de Janeiro, RJ, Brazil).

[0080] At a given time t, regarding the location of the bellows n°i (WB) i The information on the "quality" of the material above is obtained from the previous time t - Δt. i Estimated air permeability Provided, where the time offset Δt i It is a belt used to move material from the pressure measuring chamber (in this case, WB1) to the pressure measuring chamber WB. i The time spent.

[0081] Here, at each time t, the quantity It is calculated as the difference between the following two:

[0082] - For i' corresponding to the bellows where the temperature begins to rise (e.g., the bellows selected above), and

[0083] - That is, at time t, the last bellows WB N The estimated air permeability of the material.

[0084] pass Considering such an estimate of material permeability is beneficial because it allows for prediction of the quality of the material reaching the sintering zone. In this regard, it should be noted that in alternative embodiments, It can be calculated as the difference between the following two:

[0085] - For any bellows corresponding to a significant upstream location of the BTP (e.g., in the middle of the conveyor), and

[0086] - This is considered a normal breathability value.

[0087] Furthermore, it can be noted that, such as Breathability-related quantities and such The temperature-related quantities are mutually compatible because they can be added together in the error signal. In practice, when the permeability is too high (porous material, low quality), it is preferable to increase the belt speed v. And when the temperature of the pumped gas is too high, it is also preferable to increase the belt speed.

[0088] Temperature at the burn-through point (of the extracted gas) Also added to (Apart from , and (Besides). This is useful because The signal is primarily composed of information about the temperature of the pumped gas, and because at these temperatures, It is a particularly useful temperature for monitoring the sintering process.

[0089] stable loop

[0090] Stable loop 11 outputs control signal s 11 The control signal s 11 This is the setpoint for the conveyor belt speed v, and it is transmitted to actuator 3 (when stabilizing loop 11 is selected by selection logic 14). Control signal s 11 This is generated by the PID calibrator in the stabilization loop 11, whose input is the adjusted error signal. The adjusted error signal At least depends on the temperature rise slope setpoint and temperature rise slope The difference between them. As mentioned above, the temperature rise slope This represents the slope of temperature as a function of position x along belt 2 of the conveyor, upstream of the burn-through point BTP. Regarding the setpoint... It is not directly input to controller 10 (by the operator or by reading an instruction file): it also takes into account process parameters and input setpoints, as described below. Setpoints It has a non-zero value.

[0091] In this embodiment, the adjusted error signal Equal to the adjusted temperature rise slope setpoint With temperature rise slope The difference between them, where the adjusted temperature rise slope setpoint is... Combined:

[0092] - Temperature rise slope setting value and

[0093] - The exhaust gas temperature error signal mentioned above when describing correction loop 11 .

[0094] Here, the exhaust gas temperature error signal The rate controller filters the data before combining it with the temperature rise slope setpoint.

[0095] Adjusted temperature rise slope setting This is obtained by adding these quantities together:

[0096]

[0097] Therefore, the adjusted error signal Read as:

[0098]

[0099] Regarding the slope of temperature rise Not all bellows temperatures WBT i All of these are necessary to determine it. In fact, typically in the first half of the conveyor, the wind box temperature WBT i The temperature change is minimal from one bellows to another, and most of the temperature variation occurs in the latter half (last half) of the conveyor. Therefore, the temperature rise slope... It can be determined, for example, by the temperature measured in the bellows distributed in the rear half (the last half) of the conveyor (here, for example, bellows n°13 to 23, 14 to 23, or 15 to 23), or even by the temperature WBT of the last k bellows. i (For example, the last five or the last ten) are confirmed.

[0100] Temperature rise slope It can be represented, as here, as the average slope of temperature T (the temperature of the gas being drawn through the material) as a function of position x for a position range extending from the temperature rise point TRP to the burn-through point BTP.

[0101] The temperature rise point (TRP) is the point at which a significant temperature increase begins, exactly upstream of the BTP. The location of the TRP can be determined as the point where T(x) becomes above a given threshold, or as... The position where it is zero.

[0102] In the implementation considered here, the temperature rise slope TRS is determined as follows. The final set of measurements of the last 11 bellows temperatures {WBT} was collected. i} i=13…23 Numerical fitting is performed using the function T(x), which is a polynomial function of degree d (see [link to documentation]). Figure 4 In this example, d equals 3. More generally, it can be, for example, between 3 and 7. More generally, the fit can be based on the measurement set {WBT}. i} i=N-k+1…i=N (For example, for i=15 to 23).

[0103] Temperature at the burn point and its location The coordinates of the maximum value of T(x) are determined (where dT / dx cancels out). Similarly, the temperature at the point of temperature rise. and its location The coordinates of the minimum value of T(x) are determined (where dT / dx also cancels out).

[0104] Then calculate the temperature rise slope using the following formula F5. :

[0105]

[0106] or, It can be calculated as .

[0107] also, Another fitting method can be used to determine this, for example by fitting f(x) with a straight line within a given range of positions.

[0108] Now about Setting value It is used and The values ​​of both, as well as the set values ​​of the burn-through point location and temperature (denoted as...). and It is determined by ( ). and Input is made by the operator (via a human-machine interface connected to the controller 10), read by the controller in an instruction file, or otherwise received by the controller 10. Determine according to the following formula F6 (e.g.) Figure 5 (as shown)

[0109]

[0110] Used for monitoring exhaust gas temperature error signals Perform filtering (when adding it to) Previously, the rate controller (e.g., rate limiter, or setpoint filter, etc.) was not in Figure 2 As shown in [the image]. It is configured to avoid [the following]. or Overshoot occurs during the evolution (when a stabilization loop is selected). Therefore, stabilization loop 12 is provided with a signal reflecting the desired correction for the gas temperature, but conditioned to favor stability. Thus, the rate controller enables the use of a fairly aggressive correction (high gain and / or short response time) for correction loop 11 (which is desirable because inertia is very important in the sintering machine), while providing a regulated, stability-oriented version of the exhaust gas temperature error signal to stabilization loop 11.

[0111] Protection circuit

[0112] Protection circuit 13 outputs control signal s 13 The control signal s 13 This is the setpoint for the conveyor belt speed v, and it is transmitted to actuator 3 (when protection circuit 13 is selected by selection logic 14). Control signal s 13 This is generated by the PID calibrator in protection circuit 13, and its input is the error signal. The error signal At least depending on the BTP position setting. and BTP position The difference between them.

[0113] In this embodiment, the error signal It combines the following more specifically:

[0114] - The above difference ,

[0115] - The left-right asymmetry index of the sintering process, denoted as ,as well as

[0116] - The cooling rate indicator downstream of BTP, denoted as .

[0117] In this embodiment, Determine according to the following formula F7:

[0118]

[0119] The left-right asymmetry index of the sintering process can be expressed as the difference (absolute value of the difference) between the following two values, as shown here:

[0120] - Estimated position of BTP on the left side of the conveyor As confirmed above As described, the temperature measurement WBT from the left side was used in the last three bellows. il Instead of the average temperature WBT i ,

[0121] - Estimated position of BTP on the right side of the conveyor Based on the WBT temperature measurement on the right side of the last three bellows. ir Sure.

[0122] The left-right asymmetry index in the sintering process reflects the left-right asymmetry in material distribution or quality. The aforementioned left-right difference is added to the error signal. This makes it possible to achieve the following when such asymmetry exists (as when...). (When the temperature is too high, the process is slowed down (by reducing the speed v), so that high-quality sinter can be obtained despite the asymmetry.)

[0123] Cooling rate indicators of BTP downstream It can be the difference between the following two, as shown here:

[0124] - Given the cooling capacity Co, and

[0125] - BTP quantity temp - WBT N .

[0126] If the temperature does not drop sufficiently after BTP, then Add to error signal This allows the process to be slowed down, which is useful because excessively hot material at the discharge end can degrade equipment installed later.

[0127] Figure 6 The highest sintering temperature is shown in the figure. Histogram H A H A This is obtained when the sintering machine 1 is controlled by the electronic control unit 10. Figure 6 In this context, n represents the number of times each temperature sample appears. Figure 6 Another histogram H is also shown in the image. MThis shows the number of occurrences of each temperature sample when the sintering machine speed is directly and manually controlled by the operator (based on the operator's observation of process parameters). H A The width is significantly smaller than H M The width of H demonstrates the efficiency of this automatic control method. Furthermore, H A Well focused at the desired sintering temperature superior.

Claims

1. A method for controlling a sintering machine (1), the sintering machine (1) comprising a belt conveyor, the method comprising: - Obtain the bellows temperature (WBT) i The wind box temperature (WBT) i ) represents several continuous bellows (WB) arranged along the belt (2) of the conveyor. i The temperature of the material to be sintered is determined by the air box arranged below the conveyor belt, which is used to draw gas through the material (M) arranged on the conveyor belt. - Determined by at least some of the aforementioned bellows temperatures (WBT) i Determine the temperature rise slope ( The temperature rise slope represents the position at the highest temperature ( Upstream of the conveyor belt, the temperature is the slope of the belt as a function of the position (x) along the conveyor belt. - Based on the temperature rise slope ( ) and temperature rise slope setpoint ( ) Control the speed of the belt (2) of the conveyor.

2. The method according to claim 1, wherein, The temperature rise slope ( The location of the highest temperature is determined by the following: ), and the corresponding maximum temperature ( ), temperature rise location ( ) and the temperature at the location of the temperature rise ( These are determined by the temperatures of at least some of the bellows.

3. The method according to claim 2, wherein, The temperature rise slope setting value ( ) is determined by the highest temperature setting ( ), highest temperature position setting value ( The temperature rise location ( ) and the temperature at the location of the temperature rise ( It was calculated.

4. The method according to any one of claims 1 to 3, further comprising determining an exhaust gas temperature error signal ( The exhaust gas temperature error signal ( ) represents the global exhaust gas temperature setpoint ( ) and global exhaust gas temperature signal ( The difference between the global exhaust gas temperature signal and the wind box temperature depends at least on some of the wind box temperatures.

5. The method according to claim 4, wherein, The global exhaust gas temperature signal ( ) depends on the selected bellows temperature ( ).

6. The method according to claim 5, wherein, The global exhaust gas temperature signal ( The selected fan box temperature was taken into account. Multiply by the correction factor ( The correction factor is based on the selected bellows temperature ( The magnitude of time fluctuations () It is certain.

7. The method according to claim 5 or 6, wherein, The global exhaust gas temperature signal ( At least the following combination is included: the selected bellows temperature, which may have been corrected. ) and exhaust gas temperature ( ).

8. The method according to any one of claims 5 to 7, wherein, The global exhaust gas temperature signal ( At least the following combination is included: the selected bellows temperature, which may have been corrected. ) and material permeability ( The material permeability is derived from the pressure measured in one of the air boxes located below the ignition hood (4) of the sintering machine.

9. The method according to claim 8, wherein, The material's air permeability ( The determination of ) takes into account the time offset, which represents the time it takes for the belt (2) to move the material (M) from the bellows (WB1) measuring the pressure to a given position.

10. The method according to any one of claims 4 to 9, wherein, The speed of the belt is based on an adjusted error signal ( To control, the adjusted error signal ( ) equals the adjusted temperature rise slope setpoint ( ) and the temperature rise slope ( The difference between ) and ), wherein the adjusted temperature rise slope setpoint ( At least the following combinations were made: - The temperature rise slope setting value ( )and - The exhaust gas temperature error signal may have been filtered. ).

11. The method according to claim 10, wherein, The exhaust gas temperature error signal ( ) at the set value of the temperature rise slope ( The data is filtered by a rate controller before being combined with the global exhaust gas temperature signal ( ), the rate controller being configured to avoid filtering by the rate controller before the global exhaust gas temperature signal ( ). Over time, there has been a collision.

12. The method according to any one of claims 1 to 11, wherein, The speed of the conveyor belt is controlled using the following methods: - More than one control loop (11, 12, 13), which is used alternately to control the speed of the conveyor belt. - and using selection logic (14), which is configured to switch speed control from one of the control loops to the other according to a predetermined criterion.

13. The method according to claim 12, wherein, based on any one of claims 4 to 11, The control loop (11, 12, 13) includes at least: - A control loop named the stabilization loop (11), which is configured to adjust according to the temperature rise slope ( Control the speed, and - Another control loop, named the correction loop (12), is configured to adjust according to the exhaust gas temperature error signal ( And without considering the temperature rise slope ( To control the speed, And among them, when the exhaust gas temperature error signal ( When the speed exceeds the allowable range, the selection logic (14) switches the speed control from the stabilization loop (11) to the correction loop (12).

14. The method according to claim 12 or 13, wherein, The control loop (11, 12, 13) includes at least: - A control loop named the stabilization loop (11), which is configured to adjust according to the temperature rise slope ( Control the speed, and - Another control circuit, named the protection circuit (13), is configured to respond to the burn-through point error signal ( And without considering the temperature rise slope ( The speed is controlled by the burn-through point error signal. ) depends on the location of the highest temperature ( ), And among them, when the highest temperature position ( When the distance between the speed control circuit and the end of the belt conveyor becomes less than the preset distance limit, the selection logic (14) switches the speed control from the stabilization circuit to the protection circuit.

15. The method according to claim 14, wherein, The burn-through point error signal ( At least the following combinations were made: - The difference between the following two: the set value of the highest temperature position ( ) and the location of the highest temperature ( ),as well as - The location of the highest temperature ( The downstream cooling rate index ( ).

16. The method according to claim 14 or 15, wherein, The burn-through point error signal ( At least the following combinations were made: - The difference between the following two: the set value of the highest temperature position ( ) and the location of the highest temperature ( ),as well as - An index of the left-right asymmetry of the sintering process ( ).

17. An electronic control unit (10) for a sintering machine (1), configured to perform the steps of the method according to any one of the preceding claims.

18. A sintering machine (1), comprising: - Belt conveyor - Several consecutive bellows (WB1, WB2, WB) 23 The several continuous air boxes (WB1, WB2, WB23) are arranged below the conveyor belt (2) along the conveyor belt to draw gas through the material (M) to be sintered arranged on the conveyor belt. - Temperature sensors, said temperature sensors being arranged in at least some of said air boxes (WB1, WB2, WB) 23 )middle, - An electromechanical actuator (3), which is coupled to the belt (2) to drive the belt. - The electronic control unit (10) according to claim 17 is operatively connected to the temperature sensor and the electromechanical actuator (3).

19. A computer program comprising instructions that, when executed on a computer (10), cause the computer to perform a method for controlling a sintering machine according to any one of claims 1 to 16.

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