JP2005326070A - Material baking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To centralize the management of a material baking process by comprehensively controlling a preheating furnace and a rotary furnace. <P>SOLUTION: A material cut out from a material storing layer 4 is supplied to a material storing distributing part 10 formed on the preheating furnace 9, the material distributed by the material storing distributing part 10 is accumulated in a rotated and driven hearth 11 to be primarily baked, and the primarily baked material is dropped to a discharge hole 16 by a pusher 17 to be charged into a rotary kiln 20 and secondarily baked. An exhaust gas discharged from the preheating furnace 9 is diffused to the atmospheric air from a chimney 33 through a main air-exhaust ventilator 32 after cooling the exhaust gas to a range of a preferred temperature of an electric dust collector 31 at a humidity control tower 30 and removing the dust by the electric dust collector 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a raw material baking apparatus including a preheating furnace for baking agglomerated raw materials such as limestone and dolomite and a rotary furnace connected to the preheating furnace.

As a conventional raw material baking apparatus, for example, a preheating device having a deposition surface that receives agglomerated raw material supplied from the outside and forms a deposition layer, and a raw material that sequentially communicates with the preheating device and falls from the deposition surface are used. And a rotary furnace that moves the raw material to a discharge part while rotating, and the discharge part of the rotary furnace is provided with a heated gas inlet pipe for sending heated gas into the rotary furnace, An arbitrary position of the space from the space in the rotary furnace to the space in the preheating device in the baking apparatus that flows through the deposition layer after the heated gas flows countercurrently from the rotary furnace toward the preheating device. In addition, a desulfurization and firing apparatus provided with a powder feeding tube for spraying desulfurized fine powder from the outside has been proposed (see, for example, Patent Document 1).
Japanese Patent No. 3420623 (first page, FIG. 1)

However, in the conventional example described in Patent Document 1, a raw material firing apparatus in which a preheating furnace and a rotary furnace are connected is disclosed. A method for treating exhaust gas discharged from the preheating furnace is specifically described. No example is disclosed, and there is an unsolved problem that exhaust gas management cannot be performed satisfactorily.
Then, this invention is made | formed paying attention to the unsolved subject of the said prior art example, and it aims at providing the raw material baking apparatus which can perform the management of the waste gas discharged | emitted from a preheating furnace favorably. Yes.

In order to achieve the above object, the raw material baking apparatus according to claim 1 is a preheater that receives agglomerated raw material cut out and supplied from an external raw material storage tank on an annular hearth rotating around a vertical line. In a raw material firing apparatus comprising a furnace and a rotary furnace that communicates with the preheating furnace and receives the raw material falling from the hearth in a rotary drum, and moves the raw material to a discharge unit as the rotary drum rotates. The preheating furnace is configured to pre-fire the raw material deposited on the hearth with the heating gas supplied from the rotary furnace, and discharge the heated gas after the pre-firing from the exhaust pipe as an exhaust gas. The exhaust gas discharged is sucked by a main exhaust fan, cooled by a cooling tower supplied with a cooling medium, and then supplied to an electric dust collector.

Further, in the raw material firing apparatus according to claim 2, in the invention according to claim 1, the cooling tower is cooled by spraying cooling water and air as a cooling medium and spraying mist mixed with both onto exhaust gas. It is characterized by being configured.
Furthermore, the raw material baking apparatus according to claim 3 is the invention according to claim 1 or 2, wherein the cooling tower detects an inlet side exhaust gas temperature detecting means for detecting an inlet side exhaust gas temperature of the electric dust collector, and the inlet side exhaust gas. It is characterized by comprising temperature control means for controlling the flow rate of the cooling medium so that the inlet side exhaust gas temperature detected by the temperature detection means falls within the normal temperature range of the electric dust collector.

According to the invention according to claim 1, since the relatively high temperature (about 350 ° C.) exhaust gas discharged after pre-baking the raw material in the preheating furnace is cooled by the cooling medium in the cooling tower, it is supplied to the electric dust collector. An effect is obtained that the dust removal rate in the electric dust collector can be optimally controlled.
Further, according to the invention according to claim 2, since the mist mixed with cooling water and air is sprayed on the exhaust gas in the cooling tower to lower the exhaust gas temperature, the exhaust gas temperature can be accurately lowered. An effect is obtained.
According to the third aspect of the invention, the inlet exhaust gas temperature of the electrostatic precipitator is detected by the inlet exhaust gas temperature detecting means, and the cooling medium is set so that the detected outlet exhaust gas temperature is within the normal temperature range of the electrostatic precipitator. As a result, the exhaust gas temperature can be accurately controlled.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram showing a raw material baking apparatus according to the present invention. In the figure, 1 is a raw material hopper for storing raw materials in the form of agglomerates such as limestone and dolomite to be fired. The cut out raw material is sieved by the washing screen 2, and the raw material having a large particle diameter is put into the raw material storage tank 4 by the belt conveyor 3. This raw material storage tank 4 has a feeder 5 capable of controlling the amount of the raw material cut out at the lower part, and the raw material cut out by this feeder 5 passes through a horizontal conveyor 6 and further passes through a vertical conveyor 7 constituted by a bucket conveyor. The raw material discharged from the upper end of the vertical conveyor 7 is supplied to the preheating furnace 9 through the charging chute 8.

  The preheating furnace 9 is formed with a raw material storage / distribution unit 10 that stores and distributes the raw material charged from the raw material storage tank 4 at the upper portion, and rotates intermittently in a predetermined direction around a vertical line on the lower side. A pre-baking chamber 12 in which an annular plate-shaped hearth 11 to be driven is disposed is formed. Then, the raw material is supplied from the raw material storage / distribution unit 10 to the outer peripheral side of the upper furnace lid 14 constituting the pre-baking chamber 12 through the plurality of distribution supply pipes 13, so that the raw material is circled on the hearth 11. A uniform deposition layer 15 is formed in the circumferential direction. A discharge hole 16 is formed on the inner peripheral side of the hearth 11, and the inner peripheral side of the deposition layer 15 becomes a scalloped slope by the discharge hole 16 and the furnace lid 14. The raw material of the deposition layer 15 is pushed out to the inner peripheral side of the hearth 11 by a plurality of, for example, 11 pushers 17 that are spaced slightly above the upper surface of the hearth 11 and arranged in the normal direction. It is dropped into a discharge hole 16 formed on the inner peripheral side of the gas and supplied to a rotary kiln 20 serving as a rotary furnace through a communication pipe 18 that extends obliquely downward and connected to the discharge hole 16.

  In the pre-baking chamber 12, the convection heat transfer when the raw material supplied from the rotary kiln 20 through the communication pipe 18 and the discharge hole 16 and deposited on the deposition layer 15 by the heated gas flows through this and the deposition layer 15. Primary firing is performed by radiant heat transfer on the inner bowl-like inclined surface. The heated gas obtained by first firing the raw material of the deposition layer 15 in this manner is discharged to the outside through a plurality of exhaust pipes 19 provided in the upper part of the preheating firing chamber 12.

  The rotary kiln 20 has a rotary cylinder 21 formed in a horizontal cylindrical shape, and the rotary cylinder 21 has a central axis inclined to the right by a slight angle θ with respect to a horizontal plane. Is rotated at a predetermined speed. A combustion burner 22 to which a combustion gas such as C gas and primary combustion air are supplied is disposed at the raw material discharge side end opposite to the raw material supply side end where the communication pipe 18 of the rotating drum 21 is communicated. The combustion gas supplied from the combustion burner 22 is burned in the vicinity of the raw material discharge side end of the rotary drum 21 to generate a high-temperature combustion gas, and the temperature of the rotary drum 21 is set to about 1200 ° C. The raw material in the rotating drum 21 is secondarily fired. At this time, the product temperature at the discharge side end is maintained within the range of 850 ° C. to 930 ° C., and a fired product with good quality is obtained. The secondary-fired product is discharged to a product cooler 23 that extends downward and is formed at the raw material discharge side end of the rotary drum 21, and is heated by the secondary air for combustion supplied to the product cooler 23. The product is cooled to 200 ° C. or lower and supplied to the steelmaking department by a feeder 24 formed at the lower end of the product cooler 23. At this time, the temperature of the product cut out by the feeder 24 is measured by the thermometer 25.

  On the other hand, the temperature of the high-temperature (for example, about 350 ° C.) exhaust gas discharged from the discharge pipe 19 of the preheating furnace 9 is measured by a thermometer 26 provided in the discharge pipe 19 and the humidity control tower 30 as a cooling tower. Sent to. In the humidity control tower 30, reflux water and air as cooling water are applied as a cooling medium for the exhaust gas supplied from the exhaust pipe 19, and mist obtained by mixing these reflux water and air is discharged from the injection nozzle 30 a to the exhaust gas. The temperature of the exhaust gas is lowered to a temperature that can be handled by an electric dust collector (for example, 140 ° C. or lower).

  Then, a relatively low temperature exhaust gas discharged from the humidity control tower 30 is supplied to the electric dust collector 31, and dust such as a granular material contained in the exhaust gas is separated by the electric dust collector 31, and the exhaust gas from which the dust is separated is separated. The gas is sent to the chimney 33 by the main blower 32 and diffused into the atmosphere. Here, the humidity control tower 30, the electric dust collector 31, the main exhaust fan 32 and the chimney 33 constitute an exhaust gas treatment mechanism.

Moreover, the raw material supply control to the preheating furnace 9 and the raw material supply amount control to the rotary kiln 20 by the drive control of the pusher 17 of the preheating furnace 9, the temperature control of the rotary kiln 20, and the exhaust gas temperature control from the preheating furnace 9 are controlled. It is executed by the device 40.
The control device 40 displays the firing apparatus monitoring operation screen shown in FIG. 2 on the display 41, displays the current operation status on the firing apparatus monitoring operation screen, and the operation unit displayed on the firing apparatus monitoring operation screen. Is displayed, an operation screen corresponding to the operation unit is displayed.

  That is, the control device 40 includes a weight meter 51 such as a load cell that measures the weight of the tank disposed in the raw material storage tank 4, an ultrasonic level meter 52 that measures the storage level, and cuts out the raw material that is cut out because the level is detected. Each measurement value of the cut-out meter 53 for measuring the amount is inputted, and an ultrasonic level meter 54 as a raw material level detecting means for measuring the raw material level formed in the raw material storage / distribution unit 10 of the preheating furnace 9, humidity control A thermometer 26 for detecting the exhaust gas temperature at the entrance of the tower 30, a thermometer 27 for detecting the exhaust gas temperature at the entrance of the electrostatic precipitator 31, an operating state sensor 55 a as a pusher operating state detecting means for detecting the operating state of the pusher 17, and firing Infrared thermometer for detecting the measured values of the pressure sensors 55b and 55c for detecting the pressure of the outlet and the inlet of the chamber 12, and the temperature in the rotary drum 21 of the rotary kiln 20. 6. Infrared thermometer 57 for detecting the temperature of the baked product in the rotary drum 21 and infrared thermometer 58 for detecting the temperature of the baked product at the outlet of the rotary drum 21, and a pressure gauge 59 for detecting the pressure of the combustion gas , A flow meter 60 for detecting the flow rate, a pressure meter 61 for detecting the pressure of the primary air for combustion, each detected value of the flow meter 62 for detecting the flow rate, and a pressure for detecting the pressure of the reflux water supplied to the humidity control tower 30 The corresponding position in the system configuration diagram in which the detection values of the flow meter 64 for detecting the flow rate 63 and the flow meter 65 for detecting the flow rate of air are input, and the input detection values are displayed on the operation monitoring operation screen. To display. Here, the thermometers 26 and 27 correspond to the inlet temperature detection means, and the infrared thermometers 56 to 58 correspond to the rotary furnace temperature detection means.

  As shown in FIG. 2, the system configuration diagram displayed on the operation monitoring scan screen includes a raw material storage tank display unit 71 that displays the raw material level of the raw material storage tank 4 and a feeder display unit 72 that displays the operating state of the feeder 5. A raw material supply system display unit 73 for displaying the raw material supply system of the horizontal conveyor 6, the vertical conveyor 7 and the charging chute 8, a raw material storage distribution unit display unit 74 for displaying the raw material level of the raw material storage distribution unit 10, and a preheating furnace 9, a preheating furnace display unit 75 that displays the operating state of the pusher 17, a kiln display unit 76 that displays the operating state of the rotary kiln 20, a cooler display unit 77 that displays the product level of the product cooler 23, and the rotary kiln 20. A fuel supply system display section 78 indicating a fuel supply system for fuel gas, combustion air, etc., a humidity control tower display section 79 for displaying the humidity control tower 30, and an electric dust collector It includes a dust collector display unit 80 for displaying the first operation state, the exhauster display unit 81 for displaying the operation status of the main exhauster 32, and a chimney display unit 82 for displaying the chimney 33.

  Further, on the operation monitoring operation screen, an operation state correction instructing unit 83 for manually correcting the operation state, a switching time instructing unit 84 for instructing a switching time and a temperature management mode in each unit at the time of switching the firing raw material, and a firing apparatus are set up. A start-up screen instructing unit 85 for instructing display of a start-up screen used for raising, a down-compression screen instructing unit 86 for instructing display of a down-draft screen used for stopping the baking apparatus, and setting of the kiln speed A kiln speed setting instruction unit 87 for instructing a product and a product temperature trend instruction unit 88 for instructing display of a baked product temperature trend graph are provided.

Then, by moving the cursor to any one of the instruction units 83 to 88 provided on the operation monitoring operation screen, for example, by moving the cursor, for example, by performing a left click, each instruction is performed by the control device 40. Instruction operations corresponding to the units 83 to 88 are executed.
On the other hand, the control device 40 executes exhaust gas temperature management processing for managing the exhaust gas temperature discharged from the humidity control tower 30 and supplied to the electrostatic precipitator 31.

  As shown in FIG. 3, this exhaust gas temperature management process is executed as a timer interruption process for the main program at predetermined time intervals. First, in step S1, a temperature sensor 27 disposed on the entry side of the electric dust collector 31 is used. The detected incoming temperature Ti is read, and then the process proceeds to step S2 to determine whether or not the control flag F set as described later is set to “1”, and the control flag F is set to “0”. When it is reset, the process proceeds to step S3.

  In step S3, it is determined whether or not the incoming temperature Ti read in step S1 is equal to or lower than the upper limit value Tu (eg, 140 ° C.) of the normal temperature range of the electrostatic precipitator 31. If Ti ≦ Tu, step S3 is performed. In S4, a flow rate control command for maintaining the current reflux water flow rate Qw and the air flow rate Qa is output to the reflux water flow rate adjustment valve 66 and the air flow rate adjustment valve 67, and then the flow goes to Step S5. After resetting the control flag F indicating whether or not the exhaust gas temperature lowering process is being performed to “0” indicating that the exhaust gas temperature lowering process is not being performed, the timer interrupt process is terminated and the process returns to the main program.

On the other hand, when the determination result of step S3 is Ti> Tu, the process proceeds to step S6, the flow rate Qw of the reflux water is increased by a predetermined amount ΔQ, and a new flow rate Qw (= Qw + ΔQ) is calculated. The process proceeds to step S7, the calculated reflux water flow rate Qw is output to the reflux water flow rate adjustment valve 66, and then the process proceeds to step S8.
In step S8, the control flag F indicating whether or not the exhaust gas temperature lowering process is being performed is set to “1” indicating that the exhaust gas temperature lowering process is being performed, and then the timer interrupt process is terminated and the process returns to the main program. .

If the determination result in step S2 indicates that the control flag F is set to "1", it is determined that the exhaust gas temperature lowering process is in progress, and the process proceeds to step S9. It is determined whether or not the temperature drop amount ΔT obtained by subtracting the exhaust gas temperature at the time of the process is equal to or greater than the set value ΔTs, and if ΔT <ΔTs, it is determined that the exhaust gas temperature drop process is not properly performed. The process proceeds to S11.
In this step S11, a value obtained by adding the set value ΔQu to the current flow rate Qw of the reflux water is calculated as a new flow rate Qw of the reflux water, and then the process proceeds to step S12, where the calculated flow rate Qw of the reflux water is set to the reflux water. After the output to the flow rate control valve 66, the timer interruption process is terminated.

  On the other hand, when the determination result in step S10 is ΔT ≧ ΔTs, it is determined that the exhaust gas temperature lowering process is properly performed, and the process proceeds to step S13, where the exhaust gas temperature Ti is greater than the upper limit value Tu of the normal temperature range. It is determined whether or not the lower exhaust gas lower limit value Td has been reached. When Ti> Td, the timer interruption process is terminated as it is, and when Ti ≦ Td, the routine proceeds to step S14 to set the flow rate Qw of the reflux water. A new flow rate Qw reduced by the value ΔQd is calculated, and then the process proceeds to step S15, and the calculated flow rate Qw is output to the flow rate control valve 66 of the reflux water, and then the process proceeds to step S16, and in step S9. It is determined whether or not the calculated temperature drop amount ΔT is negative. If ΔT ≧ 0, the timer interrupt process is terminated, and if ΔT <0, the process proceeds to step S17. On the line, the control flag F to end the timer interrupt process is reset to "0" indicating that it is not in the exhaust gas temperature drop process.

The process of FIG. 3 corresponds to the temperature control means.
Next, the operation of the above embodiment will be described.
Now, the feeder 5 of the raw material reservoir 4, the horizontal conveyor 6, the vertical conveyor 7, the preheating furnace 9, the rotary kiln 20, the humidity control tower 30, the electric dust collector 31 and the main exhaust fan 32 are stopped, and the raw material firing system is stopped. To be.
In this state, when the control device 40 is turned on, the display control process is started. In the display control process, measurement data of each part of the raw material firing system is collected. In this case, the entire raw material firing system is stopped. Therefore, the measurement data of each part is output by the ultrasonic level meters 52 and 54 provided in the raw material reservoir 4 and the storage / distribution part 10 of the preheating furnace 9, while the actual raw material level measurement data is output. Then, the temperature data of each part outputs the temperature data of the corresponding department, and the flow rate measurement data such as combustion gas is zero.

Then, the operation monitoring operation screen display information in which these measurement data are incorporated as display data in the corresponding display location of the kiln operation monitoring operation screen is formed, and this operation monitoring operation screen display information is output to the display 41 and the display 41 The operation monitoring operation screen shown in FIG. 2 is displayed on the display screen.
In order to start up the system from the stopped state of the raw material firing system, the mouse 42 is operated to move the cursor to the start-up screen instruction unit 85 displayed on the operation monitoring operation screen displayed on the display 41. When the startup screen instruction unit 85 is selected by left-clicking in the state, the startup process is started.
In this start-up process, the start-up monitoring operation screen shown in FIG. 4 is displayed, and the temperature increase setting condition preset in the condition display unit 92 for setting the temperature increase setting condition, that is, the temperature increase time up to 750 ° C. The temperature rate, the temperature increase time up to 1000 ° C., and the temperature increase rate are displayed, and the temperature change of the rotary kiln 20 is displayed in the trend graph display section 91 below.

  In this start-up process, first, the main exhaust fan 32 is driven to make the preheating furnace 9 and the rotary kiln 20 have a negative pressure. In this negative pressure state, the fuel gas supplied to the fuel burner 22 is ignited and the temperature in the rotary drum 21 of the rotary kiln 20 is raised to 200 ° C. in about 1 hour as an initial state, and then set to 750 ° C. The temperature is increased at a temperature increase rate (for example, 35 ° C./h). During this time, when the temperature in the rotary drum 21 reaches 300 ° C., the kiln engine is continuously operated and air cooling of the furnace lid 14 of the preheating furnace 9 is started, and when the temperature reaches 500 ° C., a drive motor that rotationally drives the rotary drum 21. Start low-speed operation. Thereafter, when the temperature in the rotary drum 21 reaches 750 ° C., the charging of the raw material from the preheating furnace 9 to the rotary kiln 20 is started, and at the same time, the temperature increase rate in the rotary drum 21 is increased to, for example, about 50 ° C./h. To do.

  In the initial state, the amount of raw material charged is about 13 t / h per hour for 1 hour and then increased at 1 t / h. When the temperature in the rotary drum 21 reaches 950 ° C., the amount is increased to 3 t / h. When the amount of raw material reaches 33t, the amount is returned to 1t / h, and production is increased while checking the product quality. During this period, the rotational speed of the rotating drum 21 starts from about half of that during normal operation in the initial state, and gradually increases as the product is increased. When the internal temperature of the rotating drum 21 reaches 1200 ° C., the start-up process is completed. To normal operating condition.

  In this normal operation state, the amount of raw material cut out from the raw material storage tank 4 by the feeder 5 is set to the input target value of the rotary kiln 20, and the raw material cut out from this raw material storage layer 4 is the horizontal conveyor 6 and the vertical conveyor. 7 and the charging chute 8 are supplied in a fixed amount to the storage / distribution unit 10 of the preheating furnace 9. Since the raw material is supplied in a fixed amount to the storage / distribution unit 10 in this way, the raw material level of the storage / distribution unit 10 increases. At this time, by sequentially pushing the pusher 17 of the preheating furnace 9 at a predetermined timing, The raw material deposited on the hearth 11 of the preheating chamber 12 is pushed to the inner peripheral side, falls into the discharge hole 16, and is introduced into the rotary drum 21 of the rotary kiln 20 through the communication pipe 18. Therefore, if the push-out amount by the pusher 17, that is, the input amount to the rotary kiln 20, coincides with the raw material amount supplied to the storage / distribution unit 10, the raw material level of the storage / distribution unit 10 detected by the ultrasonic level meter 54 is substantially reduced. It becomes a constant value. Therefore, the target level of the raw material level of the storage / distribution unit 10 is set, and the push timing of the pusher 17 is set so that the raw material level is maintained at the target level, thereby accurately controlling the raw material input amount to the rotary kiln 20. can do.

  The raw material deposited in the preheating furnace 9 is primarily fired by the combustion gas supplied from the rotary kiln 20 while being deposited in the deposition layer 15, and the primary fired raw material is pushed by the pusher 17 and the rotary cylinder of the rotary kiln 20. 21 and is subjected to secondary firing while gradually moving toward the discharge side in the rotating drum 21, the product temperature is adjusted to a range of 850 ° C. to 950 ° C. maintaining a predetermined quality, and discharged to the product cooler 23, The product cooler 23 is air-cooled by secondary air and is sent to a steel mill by a feeder 24.

  On the other hand, the combustion gas from the rotary kiln 20 supplied to the preheating furnace 9 is supplied to the humidity control tower 30 through the exhaust pipe 19 as high-temperature (for example, 350 ° C.) exhaust gas after heat exchange in the deposition layer 15. The mist formed by mixing air with reflux water in the humidity control tower 30 is sprayed to cool to 140 ° C. or lower, which is the normal temperature in the electric dust collector 31, and the cooled exhaust gas is supplied to the electric dust collector 31. Then, the dust contained in the exhaust gas is separated, and the exhaust gas purified by separating the dust is diffused from the chimney 33 to the atmosphere via the main exhaust fan 32.

  At this time, the exhaust gas temperature management process of FIG. 3 is executed for the humidity control tower 30 by the control device 40, the exhaust gas temperature lowering process is not performed, and the control flag F is reset to “0”. In the state, the process proceeds from step S2 to step S3, and it is determined whether or not the exhaust gas temperature Ti on the entrance side of the electrostatic precipitator 31 is equal to or lower than the normal upper limit temperature Tu of the electrostatic precipitator 31. If Ti ≦ Tu, the exhaust gas temperature is determined. Is determined to be properly controlled, the process proceeds to step S4, the flow rate of the reflux water flow rate adjustment valve 66 is maintained at the current flow rate Qw, and the air flow rate adjustment valve 67 is maintained fully open.

  However, in this proper control state, when the inlet side exhaust gas temperature Ti of the electrostatic precipitator 31 rises and exceeds the normal upper limit temperature Tu, the process proceeds from step S3 to step S6, and the current flow rate Qw of the reflux water is set. A new flow rate Qw increased by a predetermined amount ΔQ is calculated, and the calculated flow rate command value Qw is output to the flow rate control valve 66 to start the exhaust gas temperature drop process, and a control flag F indicating this is set to “1”. Set to "".

  Thus, when the control flag F is set to “1”, the process of FIG. 3 shifts from step S2 to step S9 to calculate the temperature drop amount ΔT, and this temperature drop amount ΔT is less than the set value ΔTs. In some cases, it is determined that the exhaust gas temperature lowering process is not properly performed, and the process proceeds to step S11, where a predetermined amount ΔQ is added to the current reflux water flow rate Qw again to calculate a new flow rate command value Qw. This is output to the flow control valve 66 to increase the amount of reflux water.

  When the temperature drop amount ΔT is equal to or greater than the set value ΔTs and the exhaust gas temperature drop process is properly performed, the process proceeds from step S10 to step S13, where the exhaust gas lower limit Ti is lower than the exhaust gas upper limit temperature Tu. It is determined whether or not the temperature Td has been reached. When the exhaust gas lower limit temperature Td has not been reached, the exhaust gas temperature lowering process is continued. When the exhaust gas temperature Ti becomes equal to or lower than the exhaust gas lower limit temperature Td, the process proceeds from step S13 to step S14. Then, a predetermined value ΔQd is subtracted from the current reflux water flow rate Qw to calculate a new reflux water flow rate Qw, which is output to the flow rate control valve 66 to reduce the reflux water flow rate. When the temperature drop amount ΔT is negative, that is, when the exhaust gas temperature tends to rise, the exhaust gas temperature drop process is terminated and the control flag F is reset to “0”.

  In this way, the temperature Ti of the exhaust gas discharged from the preheating furnace 9 is controlled between the upper limit value Tu and the lower limit value Td of the normal temperature range of the electrostatic precipitator 31 by the humidity control 30 provided in the previous stage of the electrostatic precipitator 31. Therefore, accurate exhaust gas temperature management can be performed to optimally control the dust removal rate in the electric dust collector. At this time, since the mist in which the cooling water and air are mixed in the humidity control tower 30 is sprayed on the exhaust gas to lower the exhaust gas temperature, the exhaust gas temperature can be accurately lowered. In addition, when the exhaust gas temperature lowering process is finished, the flow rate of the reflux water is decreased until the exhaust gas temperature tends to rise, thereby preventing the moisture content of the exhaust gas from being maintained at a high level, It is possible to supply a small amount of exhaust gas to the electrostatic precipitator 31, and to easily perform post-treatment of the dust separated by the electrostatic precipitator.

In this normal operation state, when it is desired to change the setting value of each part, the mouse 42 is operated and the cursor is moved to the operation state correction instruction part 83 displayed on the kiln operation monitoring operation screen of FIG. By left-clicking, the correction process is started. By moving the cursor to the item to be changed and then left-clicking, if it is a correctable display part, the correction data is directly input to the display part, for example, from the keyboard. The setting data can be corrected.
When it is desired to display a product temperature trend graph in a normal operation state, the product temperature trend indication unit 88 is selected by the mouse 42 to monitor the product temperature trend graph as shown in FIG. It can be displayed on the lower left side of the operation screen, the transition of the product temperature can be displayed at a glance, and the operator can easily see it.

  Furthermore, in a normal operation state, the raw material stored in the raw material storage tank 4 is, for example, dolomite, and in the state where this dolomite is supplied to the rotary kiln 20 via the preheating furnace 9 and is fired, When changing to limestone, since it is necessary to change the firing temperature in the rotary kiln 20 in accordance with the change of the raw material, the dolomite in the raw material storage tank 4 is emptied and new limestone is charged. At that time, the switching time indicating unit 84 is selected with the mouse 42, and the firing switching display unit 84a is set to dolomite for performing firing switching → right limestone, and the time at which the switched raw material is fired is displayed as the firing time. The temperature rise rate or the temperature drop rate is displayed on the temperature rise rate display portion 84c or the temperature drop rate display portion 84d, and is further discharged from the rotary kiln 20. Feed ratio after the raw material and the switching of the time until the 50% each is displayed on the product changeover time display unit 84f. For this reason, even if the operator changes at the time of material switching, even if he forgets to send the material switching, the user can immediately grasp that the material is being switched by visually checking the data displayed on the switching instruction section 84. be able to.

  Thereafter, when the raw material firing system is stopped from the normal operation state, the blow-down monitoring operation shown in FIG. 5 is selected by selecting the blow-down screen instruction unit 86 with the mouse 42 on the kiln operation monitoring operation screen shown in FIG. A screen is displayed on the display section of the display 41. By operating the stop button on the down-flow monitoring operation screen, the combustion gas is immediately extinguished by the combustion burner 22 provided on the rotary drum 21 of the rotary kiln 20, and this At the same time, the draft is squeezed to reduce the negative pressure in the preheating furnace 9 and the main exhaust fan 32 and various blowers are stopped to eliminate the draft and increase the heat retaining effect in the preheating furnace 9 and the rotary kiln 20. In this state, the drive of the pusher 17 of the preheating furnace 9 is stopped. At this time, if the exhaust gas temperature from the preheating furnace 9 is monitored and increases, the pusher 17 is operated as a single unit and the raw material is introduced into the rotary kiln 20 to reduce the exhaust gas temperature rise. After that, when all the products remaining in the rotary drum 21 have been dispensed, the supply of primary air and secondary air for combustion is stopped, and when the temperature in the rotary drum 21 reaches 600 ° C, the drive motor is switched to the kiln engine. Then, the drive of the pusher 17 of the preheating furnace 9 and the rotation of the hearth 11 are completely stopped, and the rotary kiln 20 is completely stopped when the temperature in the rotary drum 21 is lowered to 200 ° C.

As described above, according to the embodiment, the control device 40 displays the kiln operation monitoring operation screen on the display 41, and selects the operation instruction unit included in the displayed kiln operation monitoring operation screen with the mouse 42 or the like. The start-up process, the normal operation process, and the blow-down process of the raw material firing system can be performed quickly and easily.
In addition, by correcting the data in the data display section displayed on the kiln operation monitoring operation screen, it is possible to manually intervene and also display product trend graphs, etc. It can be grasped immediately.

In addition, since the raw material level of the storage and distribution unit 10 provided in the preheating furnace 9 is detected in a normal operation state, and the push timing of the pusher 17 of the preheating furnace 9 is adjusted so that this raw material level becomes the target value, the rotary The raw material can be accurately charged into the kiln 20.
In the above embodiment, the case where each instruction unit on the kiln operation monitoring operation screen is selected and instructed by the mouse 4242 has been described. However, the present invention is not limited to this, and the execution key is operated by operating the cursor from the keyboard 43. Further, a touch sensor may be provided on the display screen of the display 41, and the touch position of the operator may be detected by this touch sensor, and the selection of the instruction unit may be input.

  Moreover, in the said embodiment, although the mist was formed by mixing reflux water and air as a cooling medium in the humidity control tower 30, and this was sprayed to exhaust gas, it is not limited to this, Only the cooling air can be used as the cooling medium. In this case, the exhaust gas temperature can be controlled within an appropriate range by adjusting the cooling air temperature or the cooling air flow rate. Further, the cooling effect may be further increased by supplying cooling air and reflux water, and any other cooling medium can be applied.

Furthermore, in the said embodiment, although the case where a combustion gas was supplied to the combustion burner 22 of the rotary kiln 20 was demonstrated, it is not limited to this, Other liquids, such as heavy oil, coal, or Solid fuel may be used.
Furthermore, in the said embodiment, although the case where the whole block diagram of a raw material baking system was displayed on the kiln driving | operation monitoring operation screen was demonstrated, it is not limited to this, The structure of a raw material baking system is divided and displayed, and desired You may make it select the display of.

1 is a system configuration diagram of a raw material baking apparatus showing an embodiment of the present invention. It is a figure which shows an example of a kiln driving | operation monitoring operation screen. It is a flowchart which shows an example of the waste gas temperature management processing procedure performed with a control apparatus. It is a figure which shows a start-up monitoring operation screen. It is a figure which shows a blow-down monitoring operation screen. It is a figure which shows the kiln driving | operation monitoring operation screen which displayed the product temperature trend graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Raw material hopper, 2 ... Flushing sieve, 4 ... Raw material storage tank, 5 ... Feeder, 6 ... Horizontal conveyor, 7 ... Vertical conveyor, 8 ... Feeding chute, 9 ... Preheating furnace, 10 ... Storage distribution part, 11 ... Hearth ,
DESCRIPTION OF SYMBOLS 12 ... Pre-baking chamber, 13 ... Distribution supply pipe, 14 ... Furnace lid, 15 ... Deposition layer, 16 ... Discharge hole, 17 ... Pusher, 18 ... Communication pipe, 19 ... Exhaust pipe, 20 ... Rotary kiln, 21 ... Rotating drum 22 ... Combustion burner, 23 ... Product cooler, 30 ... Humidity control tower, 31 ... Electric dust collector, 32 ... Main exhaust fan, 33 ... Chimney

Claims (3)

A preheating furnace that receives an agglomerated raw material cut and supplied from an external raw material storage tank on an annular hearth that rotates about a vertical line, and a raw material that communicates with the preheating furnace and falls from the hearth In a raw material baking apparatus provided with a rotary furnace that is received in the rotary drum and moves the raw material to the discharge unit as the rotary drum rotates.
The preheating furnace is configured to pre-fire the raw material deposited on the hearth with the heating gas supplied from the rotary furnace, and discharge the heated gas after the pre-firing from the exhaust pipe as an exhaust gas. A raw material calcining apparatus configured to suck exhausted exhaust gas by a main exhaust fan, cool it in a cooling tower supplied with a cooling medium, and then supply the exhaust gas to an electric dust collector.   The raw material firing according to claim 1, wherein the cooling tower is configured such that cooling water and air are input as a cooling medium, and a mist mixed with both is sprayed on the exhaust gas to cool the exhaust gas. apparatus.   The cooling tower includes an inlet-side exhaust gas temperature detecting means for detecting an inlet-side exhaust gas temperature of the electric dust collector, and an inlet-side exhaust gas temperature detected by the inlet-side exhaust gas temperature detecting means is within a normal temperature range of the electric dust collector. The raw material baking apparatus according to claim 1, further comprising a temperature control unit that controls a flow rate of the cooling medium.

Images