KR19990057626A - Control Method of Heater for Pulverized Coal - Google Patents

Abstract

The present invention relates to a control method for stabilizing the temperature of hot air for drying coal in a pulverized coal production system.

The present invention basically controls the supply amount of coal to a minimum value in order to prevent a temperature change during switching, and at the same time, the amount of supply of coal is set to the value of the air heater (1) outlet temperature controller (21), so that when the temperature rises sharply (7) In principle, it is possible to reduce the amount of combustion gas in advance in the air heater 1 outlet temperature controller 21 instead of the rear stage temperature controller 20.

According to the present invention, it is possible to directly switch 150 to the air heater operation mode 130 in the additional operation mode, so that the switching process is omitted, so that it is possible to respond quickly to changes in the operation situation, and to start the air heater 1 facility ( It is possible to prevent equipment troubles such as ignition troubles generated at the start), and to operate continuously without stopping the air heater (1) equipment, which shortens the operation mode switching time and stabilizes the temperature control. It not only enables the stable manufacture of fine pulverized coal but also prevents equipment accidents such as fire.

Description

Control Method of Heater for Pulverized Coal

The present invention relates to a control method for stabilizing the temperature of hot air for drying coal in a pulverized coal production system.

In general, the first step of the pulverized coal blowing facility in a steel mill or the like is a process for manufacturing pulverized coal, in which the coal is dried by supplying a hot gas to hot blast with a crusher receiving coal to make the crushed coal easier, It is a step of operating the operation to discharge the used hot gas to the outside while supplying to the collecting device of the upper portion. On the other hand, the exhaust gas normally generated in the blast furnace hot air maintains a specific temperature, for example, a temperature of about 200 ° C., which is sufficient to be used for drying the coal. It is common to use, and in this case, in order to smoothly produce high quality pulverized coal, the temperature 11 of the hot air should be kept constant.

In the related art, in order to keep the temperature 11 of the hot air constant, the operation of pulverized coal production as shown in the switching relationship diagram of FIG. 3 is performed according to the situation of the exhaust gas operation mode 110, the additional operation mode 120, Air heater operation mode 130 and facility stop operation mode 140. At this time, if the temperature 11 of the rear end of the shredder 7 becomes a specific temperature required for drying the coal, for example, 80 ° C. or less, water is contained in the pulverized coal, causing clogging of the blown pipe, Since the fire 11 causes the temperature 11 of the rear end of the shredder 7 to be stably maintained at 80 ° C., fine pulverized coal is produced, so that the driver may control the temperature of the hot air to manage the temperature of the rear end of the shredder 7. The operation is performed by switching the operation modes prepared in advance according to the change or the change of operation status.

In the exhaust gas operation mode 110, which is the normal operation mode, as shown in the schematic diagram of FIG. 1, the air inhaler 6 is operated to generate a specific temperature generated in the hot stove of the blast furnace through the inside of the air heater 1. For example, while controlling the high temperature exhaust gas control valve 48 and the low temperature atmospheric air control valve 49 while sucking the high temperature exhaust gas 2 of about 200 ° C., the flow rate of the hot air mixed gas as much as the required amount (13) ) Is supplied to the crusher 7 at the rear end while controlling the temperature by mixing the exhaust gas 2 and the atmospheric air 3, and the crusher 7 dries the coal supplied to facilitate crushing. At the same time, the pulverized pulverized coal is transported to the upper collecting device and hot air is released to the atmosphere.

Here, the pulverized coal is produced by the exhaust gas operation mode 110 in which the exhaust gas 2 and the atmospheric air 3 generated in the blast furnace hot air are mixed and used as the hot air. When the temperature of the crusher 7 is lowered so that the temperature 11 of the rear end of the crusher 7 cannot be maintained at 80 ° C., if it is determined that the normal pulverized coal production cannot be performed, the driver switches the operation mode to the additional operation mode 120 in the operation screen ( 111). Then, a small amount of combustion gas 5 is supplied by the combustion gas small amount setter 23 while the air heater 1 is started, and the main burner 10 is ignited. The pulverized coal production is continued while preheating the exhaust gas 2 passing through the heater 1 to raise the temperature of the exhaust gas 2 being sucked. The additional operation mode 120 is ignited with a small amount of combustion gas 5 so that when the suction amount of the exhaust gas 2 passing through the air heater 1 is large or the temperature of the exhaust gas 2 is considerably low, 7) The temperature 11 at the rear end cannot be maintained at 80 ° C. Since the additional mode operation 120 uses the exhaust gas 2 while preheating the air heater 1, the exhaust gas mode operation 110 continues even if the air heater 1 ignition trouble occurs. ) Is stopped and pulverized coal production can continue.

On the other hand, the temperature of the exhaust gas 2 is further lowered so that even after the additional operation mode 120 is executed, the rear end temperature 11 of the shredder 7 cannot be maintained at 80 ° C., or the exhaust gas 2 is exhausted from the blast furnace. When the exhaust gas 2 cannot be used as hot air because it is not generated and it is determined that the pulverized coal production is no longer possible in the additional operation mode 120, the driver switches 112 the operation mode to the air heater operation mode 130. To continue the production of pulverized coal.

At this time, in switching from the additional operation mode 120 to the air heater operation mode 130, first by stopping the air heater (1) equipment in operation in the additional operation mode 120 (Stop) operation mode 110 Is switched to 121, and then a double switching method of switching from the exhaust gas operation mode 110 to the air heater operation mode 130 is adopted. In this case, when the switching to the exhaust gas operation mode 110 is completed, the driver executes the switching 112 to the air heater operation mode 130. In this case, the pilot burner 9 generates an electric spark to produce combustion air 4 and combustion gas. After igniting (5), the air heater 1 which has just stopped is restarted to supply a large amount of combustion gas 5 to the main burner 10 to ignite the flame of the pilot burner 9, Slowly and completely close the exhaust gas control valve 48 with the waste setter 47 to completely shut off the exhaust gas 2 and open the atmospheric air control valve 49 to inhale only the atmospheric air 3 while maintaining the air heater. Pulverized coal production continues while heating (1) and preheating and using the atmospheric air 3 passing through it by the heat generated by the air heater 1. When the main burner 10 is ignited and extinguished during the conversion to the air heater operation mode 130, the equipment stop operation mode 140 in which both the exhaust gas operation mode 110 and the air heater operation mode 130 are stopped. ), The entire pulverized coal plant is stopped, making it impossible to manufacture pulverized coal.

However, in the conventional means, when switching from the additional driving mode 120 to the air heater driving mode 130 is required, the switching operation is required only through the exhaust gas driving mode 110, and thus the operation mode switching process is not duplicated. In addition, since the same air heater (1) equipment must be started, stopped, and restarted, the working time is long, so that it is difficult to respond quickly to changes in the operating situation, and the exhaust gas during the additional operation mode 120 is executed. When the temperature of (2) decreases, the operation mode can be switched only after the air heater 1 is stopped even when the temperature 11 of the rear end of the crusher cannot be maintained at 80 ° C. During this period of about 30 minutes, the temperature 11 of the exhaust gas 2 at the rear end of the crusher 7 is further lowered to increase the moisture content of the pulverized coal being manufactured, resulting in extremely poor quality and Blocking of the pipe is caused, and in particular, when switching 112 from the exhaust gas operation mode 110 to the air heater operation mode 130, a large amount of combustion gas 5 is in the state where the high temperature exhaust gas 2 is being sucked. Igniting), not only the overheating and fire of the equipment may be caused by the sudden increase in temperature, but also the ignition trouble of the air heater (1) is frequently generated. Pulverized coal cannot be manufactured for more than about 2 hours when the engine is stopped and restarted, and when the air inhaler 6 and the shredder 7 are restarted, the temperature 11 at the rear end of the shredder 7 must be naturally cooled to 60 ° C. In addition, since the motors have to be sufficiently cooled and started, there is a problem that the blowing system is affected due to the insufficient supply of pulverized coal.

The present invention has been made in order to solve the above problems, so that the air heater 1 can be switched directly to the air heater operating mode 130 in the additional operation mode 120 in the state of ignition (150), the air heater (1) Control of pulverized coal production heater which can prevent temperature control instability during ignition trouble and operation mode change, prevent temperature overheating early, and enable smooth switching operation so that pulverized coal production can be stably made To provide a way.

1 is a schematic diagram of a conventional pulverized coal manufacturing process

Figure 2 is a schematic diagram of the pulverized coal production process of the present invention

3 is a diagram illustrating a conventional operation mode switching relationship

4 is a relationship diagram of the operation mode switching according to the present invention

5 is a time chart when switching the operation mode according to the present invention

6A is a flowchart of a conventional operation mode switching process

6B is a flowchart of an operation mode switching process according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: Air Heater 2: Exhaust Gas

3: Atmosphere Air 4: Combustion Air

5: combustion gas 6: air inhaler

7: Crusher 9: Pilot Burner

10: main burner (Mail Burner) 11: shredder outlet thermometer (Thermometer)

12 air heater outlet thermometer 13 hot air flow detector

20: shredder outlet temperature controller 21: air heater outlet temperature controller

22: Low signal selector 23: Small combustion gas setter

24: combustion gas signal selector 25: combustion gas control system

30: temperature setter 40: automatic supply of minimum amount of feed

41: Coal quantity driver manual setter 42: Coal quantity signal selector

43: feed rate controller 44: hot air flow rate setting device

45: hot air regulator 46: hot air signal selector

47: exhaust gas control valve closing setter 48: exhaust gas control valve

49: atmospheric air control valve 50: exhaust gas shutoff valve

110: exhaust gas operation mode 111: switch to additional operation mode

112: Switch to air heater operation mode 120: Additional operation mode

121: Switch to exhaust gas operation mode 130: Air heater operation mode

140: Stop operation mode

150: Switch from additional operation mode to air heater operation mode

In order to achieve the above object, the present invention basically controls the supply amount of coal to a minimum in order to prevent a temperature change during switching, and at the same time, the amount of supply of coal supply becomes the set value of the air heater (1) outlet temperature controller (21), When the temperature rises, the amount of combustion gas may be reduced in advance in the air heater 1 outlet temperature controller 21 instead of the shredder 7 rear stage temperature controller 20.

The present invention is to reduce the amount of coal supply after the driver commanded the operation mode switching and the combustion gas (5) by the shredder (7) outlet temperature controller 20 and the air heater (1) outlet temperature controller (21). A control step and a program step for enabling the switching 150 from the additional driving mode 120 to the air heater driving mode 130, as shown in the switching relationship diagram of FIG. When the switch 150 is executed in the air heater operation mode 130 in step 120, the switching process proceeds as shown in the schematic diagram of FIG. 2.

In the switching process, first, the feed rate minimum value automatic setter 40 is set to an Auto state, and the feed rate signal selector 42 is switched to the number 2 by the feed quantity driver manual setter 41 to breaker ( 7) Slowly reduce the amount of coal supplied to the minimum to reduce the temperature fluctuations during the operation mode switching to prevent the temperature from dropping. After that, when the comparator determines that the minimum value is set, the temperature setter 30 is in an automatic state, and a value corresponding to the current supply amount of coal is set in the air heater 1 outlet temperature controller 21. After that, the operation pattern of various instruments is designated to supply 100% of the limited amount of combustion gas.

On the other hand, during the operation mode switching, stable temperature control is important because a large amount of the combustion gas 5 supplied in a small amount 23 is used while the high temperature exhaust gas 2 is inhaled. When the temperature rises in (1), the air heater (1) and the air inhaler (1) are already passed when the temperature rise is affected by the thermometer (11) after the air inhaler (6) and the shredder (7). 6) is a state of overheating, in order to prevent this, the output signal of the temperature controller 20 of the rear end of the shredder 7 and the output signal of the temperature controller 21 of the rear end of the air heater 1 are inputted, and the lower value is selected. An automatically selectable low signal selector 22 is provided, where the selected signal is input to the combustion gas signal selector 24.

The set value of the air heater (1) outlet temperature controller 21 calculates the amount of combustion gas (5) used in proportion to the amount of coal supply by the temperature setter (30), and this value is the generation of the air heater (1) outlet. Since the output value of the shredder 7 outlet temperature controller 20 is always selected during normal control, since it is set to the temperature 12 and then the image 20 ° C. is added, the combustion gas 5 in the air heater 1 is selected. If the heat generated by the air heater 1 becomes higher than the set value of the air heater 1 outlet temperature controller 21 due to a large supply of airflow or a deviation of the hot air flow rate 45, this value is selected before the influence on the rear end. By reducing the amount of combustion gas it is possible to prevent the temperature rise.

The combustion gas signal selector 24 is set to No. 1 and is operated by setting a constant small amount of combustion gas 5 value in the combustion gas control system 25, and then operating mode switching command signal and a small amount of supply of coal. When the setting completion signal is received, it is switched to No. 2 and the value of the low signal selector 22 is set in the flue gas regulator 25 so that the supply amount of the flue gas 5 is increased or decreased in accordance with the temperature change. On the other hand, when the operation mode switching command signal is input and the combustion gas signal selector 24 is switched to No. 2, the hot air signal selector 46 is switched to No. 2, and the exhaust gas control valve closing setter 47 becomes automatic. Slowly closes the exhaust gas control valve 48 to a value of), thereby closing the exhaust gas shutoff valve 50 to stop the intake of the exhaust gas 2 and only the atmospheric air 3 through the air heater 1. Preheating by suction allows the temperature 11 after the shredder 7 to be maintained at 80 ° C.

Therefore, according to the present invention, it is possible to switch 150 directly to the air heater operation mode 130 in the additional operation mode, so that the switching process is omitted, so that it is possible to respond quickly to changes in the operation situation, and to start the air heater 1 facility. It is possible to prevent equipment troubles such as ignition troubles generated at the start, and to operate continuously without stopping the air heater (1) equipment, which shortens the operation mode switching time and stabilizes the temperature control. Therefore, it is possible to stably manufacture fine coal dust, and to prevent facility accidents such as fire.

Claims (1)

In the control method for stabilizing the temperature of the hot air for drying coal in the pulverized coal production system, the heat generated by igniting the air heater (1) to preheat the exhaust gas (2) generated in the hot blast furnace of the blast furnace In the step of switching 150 directly to the air heater operating mode 130 for hot air by preheating only the atmospheric air 3 with the heat generated by igniting the air heater 1 from the additional operating mode 120 for hot air. And a feed amount control step of controlling the feed amount amount to a minimum in order to prevent a temperature change during switching so that continuous operation can be performed without stopping the air heater 1, and at the same time, the feed amount amount is set to the air heater 1 outlet. When the temperature rises by setting the temperature controller 21, the air heater 1 outlet temperature controller 21 can reduce the amount of combustion gas in advance instead of the temperature controller 20 after the shredder 7. Control of coal for making a heater characterized by a control step adapted to the air heater (1) the outlet temperature method