Automatic control method for pellet furnace baking process of belt type roasting machine
Through the automatic control method, the problem of uneven temperature in the pellet baking process of the belt roaster is solved, uniform heating and stable operation of the equipment are achieved, and production efficiency and the service life of refractory materials are improved.
Patent Information
- Application Number
- CN202511049555.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-09-09
AI Technical Summary
In the existing belt roaster pellet baking process, the temperature control is uneven, resulting in frequent operations and difficulty in achieving uniform heating, affecting equipment safety and production stability.
An automatic control method is adopted to obtain the oven schedule, calculate the heating rate, adjust the gas valve and fan load rate, and combine the burner start-stop and interval ignition strategies to achieve automatic temperature control and uniform heating.
It realizes the automatic control of the furnace drying process, improves the production efficiency and consistency, reduces the labor intensity of operators, extends the life of refractory materials, and ensures the stable operation of the equipment.
Smart Images
Figure CN120609216A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of metallurgical industry automation control, and in particular to an automatic control method for a pellet baking furnace process of a belt roaster. Background Art
[0002] Belt roaster is a continuous thermal equipment widely used in metallurgy, chemical industry and building materials industry. It is mainly used for oxidation roasting, reduction roasting or calcining of powdered or granular materials (such as iron ore, non-ferrous metal ore, cement raw meal, etc.).
[0003] The drying operation of a belt roaster in iron ore pellet production is a critical step in ensuring safe startup and stable operation of the equipment. It is primarily used during the temperature-raising process during new equipment commissioning, after overhauls, or after long-term shutdowns. Its core goal is to achieve uniform temperature increase, preventing cracking of the refractory material due to thermal stress, while also removing moisture, solidifying the material, and activating the roasting function.
[0004] The existing oven drying process is all controlled manually, which causes frequent operation and makes it difficult to achieve a uniform temperature rise, resulting in less than ideal oven drying effects. Summary of the Invention
[0005] In order to solve the above problems in the prior art, the present invention proposes an automatic control method for the pellet baking process of a belt roaster, which solves the problem of uneven heating during the baking process.
[0006] The present invention provides a method for automatically controlling a pellet baking process of a belt roaster, the method comprising: S10, obtaining a baking schedule; the baking schedule includes: the baking stage number, the duration of each stage, and the target temperature to be reached or maintained in that stage; S20, setting the current stage number to 1, and calculating the current stage heating rate based on the ambient temperature, the current stage target temperature, and the current stage duration; S30, start the combustion-supporting fan, main exhaust fan and furnace hood fan; S40, adjusting the gas valve of each designated burner to a preset minimum opening, starting the designated burner and delaying for a time period t1, and adjusting the gas valve of each designated burner after a time period t2 such that the average temperature of the designated burner rises to the target temperature of the current stage at the heating rate of the current stage; t1 and t2 are both preset values; S50, updating the current stage sequence number, and calculating the current stage heating rate based on the previous stage target temperature, the current stage target temperature, and the current stage duration; S60: If the target temperature of the previous stage is lower than the specified high temperature, the burners on both sides of the roaster are started and stopped in turn, and the gas valves of the burners are adjusted so that the average temperature of all the burners rises to the target temperature of the current stage according to the temperature rise rate of the current stage within the duration of the current stage, and when the average temperature of all the burners is greater than or equal to the preset roaster start temperature, the roaster, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan are started; S70, if the target temperature of the previous stage is greater than or equal to the specified high temperature, start all burners and adjust the gas valves of the burners so that the average temperature of all burners rises to the target temperature of the current stage within the time length of the current stage according to the current stage heating rate; S80, repeating steps S50 to S70 until the entire oven baking process is completed; in, The N pairs of burners of the combustion system are located at the end of the preheating section and the roasting section of the roaster, and are symmetrically distributed on both sides of the roaster; A temperature detector is provided next to each burner to detect the temperature of the flue gas next to the burner as the temperature of the burner.
[0007] Preferably, step S30 includes: Starting the combustion-supporting blower and causing the combustion-supporting blower to operate at a first load rate; The furnace hood fan is started to operate at a second load rate, and a first pressure control program is started after a delay of t3; the first pressure control program is used to adjust the frequency or damper of the furnace hood fan so that the pressure of the fume hood in the drying and drying section remains within a first pressure range until the drying process is completed; The main exhaust fan is started and operated at a third load rate, and a second pressure control program is started after a delay of t4. The second pressure control program is used to adjust the frequency or damper of the main exhaust fan so that the preheating section hood pressure remains within a second pressure range until the oven drying process is completed. The first load rate, the second load rate, the third load rate, t3, t4, the first pressure range, and the second pressure range are all preset values.
[0008] Preferably, the burners on one side of the roaster are numbered in odd-numbered order, and the burners on the other side are numbered in even-numbered order, and the two sides of the roaster are respectively referred to as the odd-numbered side and the even-numbered side; wherein, burners No. 1 and No. 2 are symmetrically distributed, burners No. 3 and No. 4 are symmetrically distributed, ..., burners No. 2N-1 and No. 2N are symmetrically distributed; The step of "alternately starting and stopping the burners on both sides of the roasting machine, and adjusting the gas valves of the burners so that the average temperature of all the burners rises to the target temperature of the current stage according to the temperature rise rate of the current stage within the time length of the current stage, and starting the roasting machine, the bottom material laying belt, the bottom material laying valve, the heat recovery fan, the cooling fan and the drying fan when the average temperature of all the burners is greater than or equal to the preset roasting machine start temperature" in step S60 includes: S61, take the gas valve opening value VO% = the preset first opening, and take the number of burner pairs started each time k = 1; S62, using an interval ignition strategy, each time starting k non-adjacent burners on the odd-numbered side and the even-numbered side and adjusting the gas valve opening to VO%, and then extinguishing after maintaining the opening for t5, and starting the burners in turn until all 2N burners are started, thereby completing a round of heating operation; t5 is a preset value; S63, obtaining the temperature of each burner and calculating the average temperature of all burners; S64: If the roasting machine has not yet started and the average temperature of all burners is greater than or equal to the preset roasting machine start temperature, start the roasting machine, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan; S65. If the difference between the average temperature of all burners and the target temperature of the current stage is within the allowable temperature deviation, and the elapsed time of the current stage is greater than or equal to the duration of the current stage, then end the current stage; otherwise, go to step S66; S66, calculating the first rising speed of the average temperature of all burners in the last round of heating operation; S67: If the first rising speed is less than the current stage heating speed, k=k+1, and go to step S62; S68: If the first rising speed is greater than the current stage temperature rising speed, reduce the gas valve opening value VO%, and go to step S62; S69: If the first rising speed is equal to the heating speed in the current stage, go to step S62.
[0009] Preferably, when k=1, step S62 includes: For the burners on the odd-numbered side, start one burner at a time starting from burner 1 in ascending order of number and keep it on for t5 before extinguishing it. Start them in turn until burner 2N-1 is started and extinguished after t5. For the burners on the even-numbered side, start one burner at a time starting from burner No. 2N in descending order of number, keep it on for t5, and then extinguish it. Start them in turn until burner No. 2 starts and extinguishes after t5. Among them, burner No. 1 and burner No. 2N are started at the same time.
[0010] Preferably, when k=2, step S62 includes: Divide the burners on the odd-numbered side and the burners on the even-numbered side into two areas from the middle, thereby obtaining four areas; Each time, a burner is started in each of the four areas and maintained for t5 time before being extinguished. It is ensured that the burner started in each area is not adjacent to the burners started in other areas, and the burner started this time in each area is not adjacent to the burner started last time in the area. They are started in turn until all 2N burners are started.
[0011] Preferably, when k=2 and N=12, step S62 includes: The 24 burners are divided into four zones; No. 1-11 is the first zone, No. 13-23 is the third zone, No. 2-12 is the second zone, and No. 14-24 is the fourth zone; Set the burner rotation order of the first zone to: 1, 5, 9, 3, 7, 11; Set the burner rotation order of the second zone to: 4, 8, 12, 2, 6, 10; Set the burner rotation order of the third zone to: 13, 17, 21, 15, 19, 23; Set the burner rotation order of the fourth zone to: 16, 20, 24, 14, 18, 22; Each time, one burner is started in each of the four areas and extinguished after maintaining the time of t5. The burners are started in turn until the burners No. 11, No. 10, No. 23 and No. 22 are started and extinguished after the time of t5.
[0012] Preferably, the step of "starting the roasting machine, the bottom material laying belt, the bottom material laying valve, the heat recovery fan, the cooling fan and the drying fan" in step S64 includes: Starting the roasting machine and making the belt of the roasting machine run at a preset speed; Start the bed material laying belt and open the bed material laying valve; Starting a heat recovery fan and a cooling fan, and making the heat recovery fan and the cooling fan operate according to a fourth load rate and a fifth load rate, respectively; The drying fan is started to operate at a sixth load rate, and a third pressure control program is started after a delay of t6. The third pressure control program is used to adjust the frequency or damper of the drying fan so that the pressure of the cooling section hood remains within a third pressure range until the drying process is completed. The fourth load rate, the fifth load rate, the sixth load rate and the third pressure range are all preset values.
[0013] Preferably, the step of "starting all burners and adjusting the gas valves of the burners so that the average temperature of all burners rises to the target temperature of the current stage within the time length of the current stage according to the heating rate of the current stage" in step S70 includes: S71, start all burners and adjust the gas valve opening of each burner to a preset second opening, and after timing t7, go to step S72; S72, obtaining the temperature of each burner and calculating the average temperature of all burners; S73. If the difference between the average temperature of all burners and the target temperature of the current stage is less than the allowable temperature deviation, and the elapsed time of the current stage is greater than or equal to the duration of the current stage, then the current stage is ended; otherwise, the process goes to step S74. S74, calculating the second rising rate of the average temperature of all burners in the previous time t7; S75, if the second rising speed is less than the current stage heating speed, increase the opening of each burner gas valve, re-time t7 and then go to step S72; S76: If the second rising speed is greater than the current stage heating speed, reduce the opening of each burner gas valve, re-time t7, and then go to step S72; S77. If the second rising speed is equal to the heating speed in the current stage, the opening of each burner gas valve is kept unchanged, and the time t7 is re-timed and the process goes to step S72.
[0014] Preferably, the oven baking schedule includes seven oven baking stages in total; The first stage corresponds to a time length of 4 days and a target temperature of 200°C; The second stage corresponds to a time length of 4 days and a target temperature of 200°C; The third stage corresponds to a time length of 2 days and a target temperature of 300°C; The fourth stage corresponds to a time length of 5 days and a target temperature of 300°C; The fifth stage corresponds to a time length of 5 days and a target temperature of 600°C; The sixth stage corresponds to a duration of 4 days and a target temperature of 1320°C; The seventh stage corresponds to a duration of 2 days and a target temperature of 1320°C; The preset roaster starting temperature is 400°C; There are two designated burners, located on both sides of the roaster, and located at the front 1 / 3 and the back 1 / 3 of the roasting area respectively; The preset minimum opening is the minimum valve opening to ensure that the flame does not go out. It is obtained through pre-testing and the default value is 25%; The specified high temperature is 600°C; t1, t3, and t4 are all 30 seconds; t2 is 10 minutes; The first load rate, the second load rate and the third load rate are 50%, 45% and 40% respectively; The first pressure range is: -60Pa±20Pa; The second pressure range is: -80Pa±20Pa.
[0015] Preferably, t5, t6 and t7 are 1 hour, 30 seconds and 3 minutes respectively; The preset speed is 1.5m / min; The fourth load rate, the fifth load rate and the sixth load rate are all 40%; The third pressure range is: -200Pa±50Pa; The preset first opening degree and the preset second opening degree are 50% and 30% respectively; The allowable temperature deviation is: ±10°C.
[0016] The present invention has the following beneficial effects: The automatic control method for the pellet drying process of a belt roaster proposed in this invention automatically executes the entire process, from reading the drying schedule to final completion, reducing manual intervention, improving production efficiency and consistency, and effectively reducing the labor intensity of operators. By rationally controlling the number of burners and the opening of the gas valve, automatic temperature control of the drying process is achieved, achieving the goal of uniform and stable drying. By alternating the starting and stopping of the burners on both sides of the roaster and adjusting the burner gas valves, local overheating of the refractory materials in the roaster can be prevented, effectively extending the life of the refractory materials and thus ensuring the stability of subsequent production.
[0017] By controlling the air volume of the furnace hood fan, main exhaust fan and dry blower fan, automatic pressure control during the drying process is achieved, which can avoid unstable combustion caused by sudden pressure changes that may occur during manual adjustment.
[0018] An interval ignition strategy is adopted, burners are selected at dispersed positions on both sides of the roaster, and the temperature is periodically detected, the gas valve opening is adjusted and the burners are rotated to ensure uniform heating to the greatest extent possible. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of process equipment and pressure detection of a belt roaster according to an embodiment of the present invention; Figure 2This is a schematic diagram of a combustion system device according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the main steps of an embodiment of the automatic control method for the pellet baking furnace process of a belt roaster in the present invention. DETAILED DESCRIPTION
[0020] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.
[0022] It should be noted that, in the description of the present invention, the terms "first" and "second" are merely for the convenience of description, and do not indicate or imply the relative importance of the devices, elements or parameters, and therefore should not be understood as limiting the present invention. In addition, the term "and / or" in the present invention is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document, unless otherwise specified, generally indicates that the associated objects are in an "or" relationship.
[0023] Figure 1 Schematic diagram of the process equipment and pressure detection of the belt roasting machine in the embodiment of the present invention. Figure 1 As shown, the belt roaster includes the following process sections: drying, extraction, preheating, roasting, soaking, first cooling, and second cooling sections. The hood fan is installed at the top of the drying section and draws air outward. Its core function is to maintain the pressure in the drying section hood (i.e., pressure 1 in the figure) within a preset first pressure range. The main exhaust fan is used to extract hot and humid air from the extraction, preheating, and roasting sections, and to maintain the preheating section hood pressure (i.e., pressure 2 in the figure) within a preset second pressure range. The reheat fan is used to extract high-temperature hot air from the roasting and soaking sections and circulate it to the drying section to improve the system's thermal efficiency. The cooling fan is used to blow cold air into the first and second cooling sections. The drying fan is used to extract hot air from the second cooling section and circulate it to the drying section, and to maintain the cooling section hood pressure (i.e., pressure 3 in the figure) within a preset third pressure range. The combustion system (including the combustion-supporting fan and gas pipelines) is located at the end of the preheating section and in the roasting section of the roaster.
[0024] Figure 2 FIG. 1 is a schematic diagram of the combustion system equipment in an embodiment of the present invention. Figure 2 As shown, the combustion system consists of N pairs of burners located at the end of the preheating section and the roasting section of the roaster, symmetrically distributed on both sides of the roaster. The number of burners depends on the roaster's production capacity and process conditions, typically ranging from 12 to 16 pairs. The burners on one side of the roaster are numbered in odd-numbered order, while those on the other side are numbered in even-numbered order. For ease of description, the two sides of the roaster are referred to in this application as the odd-numbered side and the even-numbered side, respectively. Burners 1 and 2 are symmetrically distributed, burners 3 and 4 are symmetrically distributed, ..., and burners 2N-1 and 2N are symmetrically distributed. Each burner corresponds to a gas pipeline and a combustion air pipeline. Each burner's gas pipeline is equipped with a gas valve, while the combustion air pipeline of a single burner does not have a valve. The combustion air for all burners is controlled by adjusting the frequency or damper of the combustion air fan. A temperature detector (not shown) is installed next to each burner to measure the temperature of the flue gas near the burner, which is used as the burner temperature. Except for the need to adjust the combustion-supporting air during the furnace opening and heating process (because in the early stage of the furnace baking process, the burner flow is very small and the temperature is very low, and there is a fear that the air volume will be too large and blow out the burner), there is no need to adjust the combustion-supporting air volume during normal production, because part of the air volume involved in burner combustion comes from the cold air of the combustion fan, and the other part comes from the hot air from the cooling fan after being heated by the high-temperature material layer.
[0025] Figure 3 Schematic diagram of the main steps of the embodiment of the automatic control method of the pellet baking process of the belt roaster in the present invention. Figure 3 As shown, the method of this embodiment includes steps S10-S80: S10. Obtaining a baking schedule.
[0026] The oven schedule includes the oven stage number, the duration of each stage, and the target temperature to be reached or maintained during that stage. The oven schedule can be input by the user through the human-computer interface or received remotely via the network.
[0027] In this embodiment, the oven baking schedule has seven stages, numbered 1, 2, ..., 7. The first stage has a duration of 4 days and a target temperature of 200°C; the second stage has a duration of 4 days and a target temperature of 200°C; the third stage has a duration of 2 days and a target temperature of 300°C; the fourth stage has a duration of 5 days and a target temperature of 300°C; the fifth stage has a duration of 5 days and a target temperature of 600°C; the sixth stage has a duration of 4 days and a target temperature of 1320°C; and the seventh stage has a duration of 2 days and a target temperature of 1320°C.
[0028] S20, set the current stage number to 1, and calculate the current stage heating rate based on the ambient temperature, the current stage target temperature and the current stage time length, as shown in formula (1): Dt1=(T1-T0) / H1 (1) Where Dt1 is the heating rate of the current stage (stage 1), T1 is the target temperature of the current stage, T0 is the ambient temperature, and H1 is the duration of the current stage. According to the above oven schedule, T1 = 200°C, H1 = 4 days. Assuming the ambient temperature is 0°C, substituting it into formula (1) yields Dt1 = 2.08°C.
[0029] S30, start the combustion-supporting fan, main exhaust fan and furnace hood fan.
[0030] This step may specifically include steps S31-S33: S31. Start the combustion-supporting blower and operate it at a first load rate.
[0031] Among them, the first load rate is a preset value of 50%, which can be set by adjusting the frequency by 25HZ (for variable frequency fans) or adjusting the air damper by 50% (for fixed frequency fans).
[0032] S32: Start the furnace hood fan and operate it at the second load rate. After a delay of t3 (30 seconds), start the first pressure control program.
[0033] Among them, the second load rate is a preset value of 45%, which can be set by adjusting the frequency to 22.5HZ (for variable frequency fans) or adjusting the air damper to 45% (for fixed frequency fans); the first pressure control program is used to adjust the frequency or air damper of the furnace hood fan so that the hood pressure of the drying section is maintained within the first pressure range (-60Pa±20Pa) until the drying process is completed.
[0034] S33: Start the main exhaust fan and make it run at the third load rate. After a delay of t4 (30 seconds), start the second pressure control program.
[0035] Among them, the third load rate is a preset value of 40%, which can be set by adjusting the frequency by 20HZ (for variable frequency fans) or adjusting the air damper by 40% (for fixed frequency fans); the second pressure control program is used to adjust the frequency or air damper of the main exhaust fan so that the preheating section hood pressure remains within the second pressure range (-80Pa±20Pa) until the baking process is completed.
[0036] S40, adjust the gas valve of each designated burner to the preset minimum opening, start the designated burner and delay t1 (30 seconds), and adjust the gas valve of each designated burner after every t2 time (10 minutes) so that the average temperature of the designated burner rises to the target temperature of the current stage according to the current stage heating rate.
[0037] Among them, t1 and t2 are both preset values; in this embodiment, two burners are designated, which are located on both sides of the roasting machine, and are located at the front 1 / 3 and the back 1 / 3 of the roasting area respectively; the preset minimum opening is the minimum valve opening to ensure that the flame is not extinguished, which is obtained through pre-testing and the default value is 25%.
[0038] S50, update the current stage number, and calculate the current stage heating rate according to the target temperature of the previous stage, the target temperature of the current stage and the duration of the current stage, as shown in formula (2): Dt i =(T i -T i-1 ) / H i (2) Among them, i is the updated current stage number, Dt i is the calculated heating rate at the current stage, T i and T i-1 are the target temperature of the current stage and the target temperature of the previous stage, H i The duration of the current stage.
[0039] If the target temperature of the previous stage is less than the target temperature of the current stage, it means that the temperature needs to be increased in the current stage, and the current stage heating rate calculated according to the above formula (2) is greater than zero. If the target temperature of the previous stage is equal to the target temperature of the current stage, it means that the temperature needs to be kept constant in the current stage, and the current stage heating rate calculated according to the above formula (2) is zero. The following steps S60 and S70 respectively operate for the cases where the target temperature of the previous stage is less than the specified high temperature and greater than or equal to the specified high temperature. The main difference is that in S60, the burners are started and stopped in turn, while in S70, all burners are started.
[0040] S60: If the target temperature of the previous stage is lower than the specified high temperature (600°C), the burners on both sides of the roaster are started and stopped in turn, and the gas valves of the burners are adjusted so that the average temperature of all burners rises to the target temperature of the current stage at the current stage heating rate within the duration of the current stage. When the average temperature of all burners is greater than or equal to the preset roaster start temperature, the roaster, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan are started. This specifically includes steps S61-S69: S61: Set the gas valve opening value VO% = the preset first opening, and set the number of burner pairs started each time k = 1. The preset first opening is 50%.
[0041] S62. Use an intermittent ignition strategy, activating k non-adjacent burners on both the odd-numbered and even-numbered sides at a time, adjusting the gas valve opening to VO%. Maintaining these ignitions for t5 (1 hour) before extinguishing them, the burners are activated in turn until all 2N burners are activated, completing one round of heating. t5 is a preset value.
[0042] The purpose of adopting the interval ignition strategy is to keep the distance between the burners started at the same time as far as possible, so as to avoid the damage to the life of the refractory material due to the rapid rise of local temperature in the roasting furnace.
[0043] S63. Obtain the temperature of each burner and calculate the average temperature of all burners.
[0044] S64: If the roasting machine has not yet started and the average temperature of all burners is greater than or equal to the preset roasting machine starting temperature (400°C), start the roasting machine, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan. The startup steps may specifically include: (1) Start the roasting machine and make the roasting machine belt run at the preset speed.
[0045] (2) Start the base material laying belt and open the base material laying valve.
[0046] (3) Start the heat recovery fan and the cooling fan, and make the heat recovery fan and the cooling fan operate according to the fourth load rate and the fifth load rate respectively.
[0047] (4) Start the drying fan and make it run at the sixth load rate, and start the third pressure control program after a delay of t6 (30 seconds).
[0048] Among them, the third pressure control program is used to adjust the frequency or damper of the drying fan so that the pressure of the cooling section hood remains within the third pressure range until the drying process is completed; the fourth load rate, the fifth load rate and the sixth load rate are all 40%; the third pressure range is the preset value (-200±50Pa); the preset speed is 1.5m / min.
[0049] S65: If the difference between the average temperature of all burners and the target temperature of the current stage is within the allowable temperature deviation, and the duration of the current stage is greater than or equal to the duration of the current stage, then the current stage is terminated; otherwise, the process proceeds to step S66. The allowable temperature deviation is: ±10°C.
[0050] S66. Calculate the first rising speed of the average temperature of all burners in the last round of heating operation.
[0051] S67. If the first rising speed is less than the heating speed in the current stage, k=k+1, and go to step S62.
[0052] S68: If the first rising speed is greater than the current stage temperature rising speed, reduce the gas valve opening value VO%, and go to step S62.
[0053] S69: If the first rising speed is equal to the heating speed in the current stage, go to step S62.
[0054] S70: If the target temperature of the previous stage is greater than or equal to the specified high temperature, all burners are started and the gas valves of each burner are adjusted so that the average temperature of all burners rises to the target temperature of the current stage within the time length of the current stage according to the current stage heating rate. This step may specifically include steps S71-S77: S71: Start all burners and adjust the gas valve opening of each burner to a preset second opening. After timing t7 (3 minutes), go to step S72. The preset second opening is 30%.
[0055] S72. Obtain the temperature of each burner and calculate the average temperature of all burners.
[0056] S73. If the difference between the average temperature of all burners and the target temperature of the current stage is less than the allowable temperature deviation, and the time elapsed in the current stage is greater than or equal to the time length of the current stage, then end the current stage; otherwise, go to step S74.
[0057] S74: Calculate the second rising rate of the average temperature of all burners in the previous time period t7.
[0058] S75. If the second rising speed is less than the heating speed in the current stage, increase the opening of each burner gas valve, re-time the time t7, and then go to step S72.
[0059] S76: If the second rising speed is greater than the current stage heating speed, reduce the opening of each burner gas valve, re-time the time t7 and then go to step S72.
[0060] S77. If the second rising speed is equal to the current stage heating speed, the opening of each burner gas valve is kept unchanged, and the time t7 is re-timed and the process goes to step S72.
[0061] S80, repeating steps S50 to S70 until the entire baking process is completed.
[0062] In an optional embodiment, when k=1, step S62 includes: (1) For the burners on the odd-numbered side, start one burner at a time starting from burner No. 1 in ascending order and keep it on for t5 time (1 hour) before extinguishing it. Start them in turn until burner No. 2N-1 is started and extinguished after t5 time.
[0063] (2) For the burners on the even-numbered side, start one burner at a time starting from burner No. 2N in descending order of number and keep it on for t5 before extinguishing it. Start them in turn until burner No. 2 starts and extinguishes it after t5.
[0064] Burners 1 and 2N are started simultaneously. Assuming N = 12, burners 1 and 24 are started first, followed by burners 3 and 22, then burners 5 and 20, and so on, until burners 23 and 2 are started. This method is designed to keep the distance between the two burners started at any one time as far as possible to prevent localized temperature increases within the furnace from occurring too quickly.
[0065] In the above optional embodiment, when k=2, step S62 includes: (1) Divide the burners on the odd-numbered side and the burners on the even-numbered side into two areas from the middle, resulting in four areas.
[0066] (2) Start one burner in each of the four areas each time and keep it on for t5 time (1 hour) before extinguishing. Ensure that the burners started in each area are not adjacent to the burners started in other areas, and the burners started in each area this time are not adjacent to the burners started last time in the area. Start them in turn until all 2N burners are started.
[0067] The roasting machine in the embodiment of the present invention has 24 burners (N=12). When k=2, step S62 includes: The 24 burners are divided into four areas.
[0068] Among them, No. 1-11 is the first zone, No. 13-23 is the third zone, No. 2-12 is the second zone, and No. 14-24 is the fourth zone. Each zone contains 6 burners.
[0069] (2) Set the burner rotation sequence of the first zone to: 1, 5, 9, 3, 7, 11; set the burner rotation sequence of the second zone to: 4, 8, 12, 2, 6, 10; set the burner rotation sequence of the third zone to: 13, 17, 21, 15, 19, 23; set the burner rotation sequence of the fourth zone to: 16, 20, 24, 14, 18, 22.
[0070] (3) Start one burner in each of the four zones at a time and keep it on for t5 before extinguishing it. Start them in turn until burners No. 11, No. 10, No. 23 and No. 22 are started and extinguished after t5.
[0071] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.
[0072] Those skilled in the art should be able to appreciate that the method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.
[0073] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is clearly not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent modifications or substitutions to the relevant technical features, and the technical solutions after such modifications or substitutions will fall within the scope of protection of the present invention.
Claims
1. A method for automatically controlling the pelletizing process of a belt roaster, characterized in that: The method comprises: S10, obtaining a baking schedule; the baking schedule includes: the baking stage number, the duration of each stage, and the target temperature to be reached or maintained in that stage; S20, setting the current stage number to 1, and calculating the current stage heating rate based on the ambient temperature, the current stage target temperature, and the current stage duration; S30, start the combustion-supporting fan, main exhaust fan and furnace hood fan; S40, adjusting the gas valve of each designated burner to a preset minimum opening, starting the designated burner and delaying for a time period t1, and adjusting the gas valve of each designated burner after a time period t2 such that the average temperature of the designated burner rises to the target temperature of the current stage at the heating rate of the current stage; t1 and t2 are both preset values; S50, updating the current stage sequence number, and calculating the current stage heating rate based on the previous stage target temperature, the current stage target temperature, and the current stage duration; S60: If the target temperature of the previous stage is lower than the specified high temperature, the burners on both sides of the roaster are started and stopped in turn, and the gas valves of the burners are adjusted so that the average temperature of all the burners rises to the target temperature of the current stage according to the temperature rise rate of the current stage within the duration of the current stage, and when the average temperature of all the burners is greater than or equal to the preset roaster start temperature, the roaster, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan are started; S70, if the target temperature of the previous stage is greater than or equal to the specified high temperature, start all burners and adjust the gas valves of the burners so that the average temperature of all burners rises to the target temperature of the current stage within the time length of the current stage according to the current stage heating rate; S80, repeating steps S50 to S70 until the entire oven baking process is completed; in, The N pairs of burners of the combustion system are located at the end of the preheating section and the roasting section of the roaster, and are symmetrically distributed on both sides of the roaster; A temperature detector is provided next to each burner to detect the temperature of the flue gas next to the burner as the temperature of the burner.
2. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 1, characterized in that: Step S30 includes: Starting the combustion-supporting blower and causing the combustion-supporting blower to operate at a first load rate; The furnace hood fan is started to operate at a second load rate, and a first pressure control program is started after a delay of t3; the first pressure control program is used to adjust the frequency or damper of the furnace hood fan so that the pressure of the fume hood in the drying and drying section remains within a first pressure range until the drying process is completed; The main exhaust fan is started and operated at a third load rate, and a second pressure control program is started after a delay of t4. The second pressure control program is used to adjust the frequency or damper of the main exhaust fan so that the preheating section hood pressure remains within a second pressure range until the oven drying process is completed. The first load rate, the second load rate, the third load rate, t3, t4, the first pressure range, and the second pressure range are all preset values.
3. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 1, characterized in that: The burners on one side of the roaster are numbered in odd-numbered order, and the burners on the other side are numbered in even-numbered order. The two sides of the roaster are respectively referred to as the odd-numbered side and the even-numbered side. Burners 1 and 2 are symmetrically distributed, burners 3 and 4 are symmetrically distributed, ..., burners 2N-1 and 2N are symmetrically distributed. In step S60, the step of "alternately starting and stopping the burners on both sides of the roaster, and adjusting the gas valves of the burners so that the average temperature of all the burners rises to the target temperature of the current stage according to the temperature rise rate of the current stage within the time length of the current stage, and when the average temperature of all the burners is greater than or equal to the preset roaster start temperature, starting the roaster, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan and the drying fan" includes: S61, take the gas valve opening value VO% = the preset first opening, and take the number of burner pairs started each time k = 1; S62, using an interval ignition strategy, each time starting k non-adjacent burners on the odd-numbered side and the even-numbered side and adjusting the gas valve opening to VO%, and then extinguishing after maintaining the opening for t5, and starting the burners in turn until all 2N burners are started, thereby completing a round of heating operation; t5 is a preset value; S63, obtaining the temperature of each burner and calculating the average temperature of all burners; S64: If the roasting machine has not yet started and the average temperature of all burners is greater than or equal to the preset roasting machine start temperature, start the roasting machine, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan, and the drying fan; S65. If the difference between the average temperature of all burners and the target temperature of the current stage is within the allowable temperature deviation, and the elapsed time of the current stage is greater than or equal to the duration of the current stage, then end the current stage; otherwise, go to step S66; S66, calculating the first rising speed of the average temperature of all burners in the last round of heating operation; S67: If the first rising speed is less than the current stage heating speed, k=k+1, and go to step S62; S68: If the first rising speed is greater than the current stage temperature rising speed, reduce the gas valve opening value VO%, and go to step S62; S69: If the first rising speed is equal to the heating speed in the current stage, go to step S62.
4. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 3, characterized in that: When k=1, step S62 includes: For the burners on the odd-numbered side, start one burner at a time starting from burner 1 in ascending order of number and keep it on for t5 before extinguishing it. Start them in turn until burner 2N-1 is started and extinguished after t5. For the burners on the even-numbered side, start one burner at a time starting from burner No. 2N in descending order of number, keep it on for t5, and then extinguish it. Start them in turn until burner No. 2 starts and extinguishes after t5. Among them, burner No. 1 and burner No. 2N are started at the same time.
5. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 3, characterized in that: When k=2, step S62 includes: Divide the burners on the odd-numbered side and the burners on the even-numbered side into two areas from the middle, thereby obtaining four areas; Each time, a burner is started in each of the four areas and maintained for t5 time before being extinguished. It is ensured that the burner started in each area is not adjacent to the burners started in other areas, and the burner started this time in each area is not adjacent to the burner started last time in the area. They are started in turn until all 2N burners are started.
6. The automatic control method for pelletizing furnace process of belt roaster according to claim 5, characterized in that: When k=2 and N=12, step S62 includes: The 24 burners are divided into four zones; No. 1-11 is the first zone, No. 13-23 is the third zone, No. 2-12 is the second zone, and No. 14-24 is the fourth zone; Set the burner rotation order of the first zone to: 1, 5, 9, 3, 7, 11; Set the burner rotation order of the second zone to: 4, 8, 12, 2, 6, 10; Set the burner rotation order of the third zone to: 13, 17, 21, 15, 19, 23; Set the burner rotation order of the fourth zone to: 16, 20, 24, 14, 18, 22; Each time, one burner is started in each of the four areas and extinguished after maintaining the time of t5. The burners are started in turn until the burners No. 11, No. 10, No. 23 and No. 22 are started and extinguished after the time of t5.
7. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 3, characterized in that: The step of "starting the roasting machine, the bed material laying belt, the bed material laying valve, the heat recovery fan, the cooling fan and the drying fan" in step S64 includes: Starting the roasting machine and making the belt of the roasting machine run at a preset speed; Start the bed material laying belt and open the bed material laying valve; Starting a heat recovery fan and a cooling fan, and making the heat recovery fan and the cooling fan operate according to a fourth load rate and a fifth load rate, respectively; The drying fan is started to operate at a sixth load rate, and a third pressure control program is started after a delay of t6. The third pressure control program is used to adjust the frequency or damper of the drying fan so that the pressure of the cooling section hood remains within a third pressure range until the drying process is completed. The fourth load rate, the fifth load rate, the sixth load rate and the third pressure range are all preset values.
8. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 7, characterized in that: The step of "starting all burners and adjusting the gas valves of the burners so that the average temperature of all burners rises to the target temperature of the current stage within the time length of the current stage according to the heating rate of the current stage" in step S70 includes: S71, start all burners and adjust the gas valve opening of each burner to a preset second opening, and after timing t7, go to step S72; S72, obtaining the temperature of each burner and calculating the average temperature of all burners; S73. If the difference between the average temperature of all burners and the target temperature of the current stage is less than the allowable temperature deviation, and the elapsed time of the current stage is greater than or equal to the duration of the current stage, then the current stage is ended; otherwise, the process goes to step S74. S74, calculating the second rising rate of the average temperature of all burners in the previous time t7; S75, if the second rising speed is less than the current stage heating speed, increase the opening of each burner gas valve, re-time t7 and then go to step S72; S76: If the second rising speed is greater than the current stage heating speed, reduce the opening of each burner gas valve, re-time t7, and then go to step S72; S77. If the second rising speed is equal to the heating speed in the current stage, the opening of each burner gas valve is kept unchanged, and the time t7 is re-timed and the process goes to step S72.
9. The automatic control method for the pelletizing furnace process of a belt roaster according to claim 2, characterized in that: The oven baking schedule includes seven oven baking stages; The first stage corresponds to a time length of 4 days and a target temperature of 200°C; The second stage corresponds to a time length of 4 days and a target temperature of 200°C; The third stage corresponds to a time length of 2 days and a target temperature of 300°C; The fourth stage corresponds to a time length of 5 days and a target temperature of 300°C; The fifth stage corresponds to a time length of 5 days and a target temperature of 600°C; The sixth stage corresponds to a duration of 4 days and a target temperature of 1320°C; The seventh stage corresponds to a duration of 2 days and a target temperature of 1320°C; The preset roaster starting temperature is 400°C; There are two designated burners, located on both sides of the roaster, and located at the front 1 / 3 and the back 1 / 3 of the roasting area respectively; The preset minimum opening is the minimum valve opening to ensure that the flame does not go out. It is obtained through pre-testing and the default value is 25%; The specified high temperature is 600°C; t1, t3, and t4 are all 30 seconds; t2 is 10 minutes; The first load rate, the second load rate and the third load rate are 50%, 45% and 40% respectively; The first pressure range is: -60Pa±20Pa; The second pressure range is: -80Pa±20Pa.
10. The automatic control method for pelletizing furnace process of belt roaster according to claim 8, characterized in that: t5, t6, and t7 are 1 hour, 30 seconds, and 3 minutes, respectively; The preset speed is 1.5m / min; The fourth load rate, the fifth load rate and the sixth load rate are all 40%; The third pressure range is: -200Pa±50Pa; The preset first opening degree and the preset second opening degree are 50% and 30% respectively; The allowable temperature deviation is: ±10°C.