JPH0576997B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic heating and drying method for a pulverized coal manufacturing apparatus that supplies pulverized coal to a pulverized coal supply device such as a powder injection device to a blast furnace.

[Conventional technology]

Generally, in blast furnace operations, pulverized coal is injected together with blast air through the tuyeres as an alternative fuel to coke in order to properly manage reaction factors in the furnace. Conventionally, there are manufacturing apparatuses disclosed in Japanese Patent Laid-Open Nos. 57-145908 and 59-56495.

An example of these pulverized coal manufacturing devices is shown in FIG. As shown in the figure, lumpy coking coal containing a large amount of moisture is cut out from the raw material tank 1, and is supplied via the feeding conveyor 2 to the coal feed bin 3 for material sealing the negative pressure inside the pulverizing dryer. The coal is fed through a feeder 4 to a coal pulverizer and dryer 5 where it is pulverized and dried. This pulverized and dried pulverized coal is air-transported to collectors such as a cyclone 7 and a bag filter 8 by suction with a blower 6, where the pulverized coal is separated from the air flow and collected, and sent to the blast furnace as powder. The pulverized coal is supplied to a pulverized coal supply device 9 such as a body blowing device. Note that 10 is a chimney connected to the outlet side of the blower 6.

The suction capacity of this pulverized coal airflow transport system is determined by detecting the inlet pressure of the coal pulverizing dryer 5 and opening the suction damper 11 inserted between the blower 6 and bag filter 8 to keep it constant. It is controlled by adjusting the degree of

Further, hot air for drying and transporting raw coal is supplied to the coal crushing/drying machine 5 through a supply pipe 12. The temperature of this hot air is controlled using low oxygen concentration gas such as blast furnace hot air exhaust gas, as the pulverized coal is a combustible powder and there is a risk of causing a powder explosion or fire if certain conditions are reached. It is desirable to do so, and the hot air exhaust gas is often reheated in the hot air generating furnace 13 for heating and then supplied to the coal pulverizer/dryer 5.

Furthermore, an outside air suction pipe 14 is provided in the air flow transport system.
In many processes, the hot air temperature is controlled by connecting the hot air damper 15 and the cold air damper 16 to adjust the openings. In order to avoid storage, the hot air damper 15 is normally fully opened and the cold air damper 16 is fully closed, and an operating method is used in which the cold air damper 16 is opened only when ventilation is desired during startup and shutdown.

In the above-mentioned pulverized coal production equipment, as a temperature increase control method from startup to temperature rise to the normal state, the necessary Due to different pressure conditions, the suction damper 11
By adjusting the pressure, the pressure is set to a state where it is easy to ignite, and when the temperature rise is completed and the suction capacity is increased to a stable state, the mode is manually switched to the automatic mode.When the temperature rises, the hot air damper 15
Also, while adjusting the cold air damper 16 together with the suction damper 11, the work of raising the temperature was also done manually by looking at not only the pressure but also the air volume and temperature conditions.

[Problem that the invention seeks to solve]

However, the conventional temperature increase control method described above requires various manual operations at startup, which places a heavy burden on the operator, making it difficult to perform stable operations, and frequently causing problems due to incorrect operations. . In addition, when the temperature rises, the hot air damper 15,
While manually adjusting the cold air damper 16 together with the suction damper 11, the temperature is raised based on not only the pressure but also the air volume and temperature conditions, so depending on the damper opening degree, the cold air may be the main source, or the hot air furnace exhaust gas may be the main source. In the former case, it takes time to raise the temperature, resulting in poor equipment operation efficiency; in the latter case, it takes only a short time to raise the temperature, but until the target temperature is reached, there is a There is a risk of condensation on the filter cloth of the pulverized coal, and in particular, if the exhaust gas from the hot blast furnace condenses on the bag filter, it will take many days to dry the condensation process, and during that time the operation of the pulverized coal production equipment will have to be stopped. The problem was that they would incur huge losses.

Therefore, the present invention has been made by focusing on the problems of the above-mentioned conventional example, and by automatically controlling the temperature rising process from the time of startup of the pulverized coal manufacturing equipment until reaching a predetermined set temperature, The purpose of this invention is to solve the problems of the above-mentioned conventional example.

[Means for solving problems]

In order to achieve the above object, the present invention provides a coal pulverizing dryer that pulverizes and dries raw coal to produce pulverized coal, and supplies hot air for drying by reheating hot blast furnace exhaust gas to the coal pulverizing dryer. In a pulverized coal manufacturing equipment that includes a hot air generating furnace and a blower for generating transport air flow connected to the coal pulverizing dryer through a pulverized coal separation and collector including a bag filter, hot air is Until the furnace exhaust gas reaches the dew point, the ratio of cold air to the hot air furnace exhaust gas is gradually lowered while monitoring the outlet temperature and humidity of the bag filter, and the temperature control operation amount is increased in steps to prevent condensation. From the dew point until the set temperature is reached, the temperature is raised using only the hot stove exhaust gas.
The present invention is characterized in that the outlet temperature control of the coal pulverizer/dryer is automatically started when the set temperature is reached.

[Effect]

This invention provides a pulverized coal manufacturing apparatus in which, in the temperature rising process after the ignition of the hot air generating furnace at the time of startup,
Until the hot air stove exhaust gas reaches the dew point, the temperature control operation amount is increased stepwise by gradually decreasing the ratio of cold air to the hot air furnace exhaust gas while monitoring the temperature and humidity at the outlet side of the bag filter. The temperature is raised while preventing dew condensation on the coal transport route and the filter cloth of the bag filter.

When the dew point is exceeded, the heating time is shortened by raising the temperature using only the hot blast furnace exhaust gas, and when the set temperature is reached, the outlet temperature control of the pulverizing dryer is automatically started, and coking coal is added to the pulverizing dryer. Start supplying.

On the other hand, the setting value of the inlet pressure control of the coal pulverizer/dryer is automatically changed to enable stable ignition by setting it to a high value close to atmospheric pressure at the time of ignition, and setting it to a low value when the temperature rises, allowing the pulverized coal from the coal pulverizer/dryer to be controlled at a low value. Use the pressure necessary for pneumatic transportation.

By automatically performing the above operations, the problems of the conventional example can be solved.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing a processing procedure of an arithmetic processing unit, and FIG. 3 is a waveform diagram for explaining the operation of the present invention.

In Fig. 1, 1 is a raw material tank, 2 is an input conveyor, 3 is a coal feed bin, 4 is a chain feeder, 5 is a coal crushing dryer, 6 is a blower, 7 is a cyclone, 8 is a bag filter, and 9 is a pulverized coal coating. Supply device, 10 is a chimney, 11 is a suction damper, 12
is a hot air furnace exhaust gas supply pipe, 13 is a hot air generating furnace, 14
1 is an outside air suction pipe, 15 is a hot air damper, and 16 is a cold air damper, which are connected in the same manner as in the conventional example.

The hot air generating furnace 13 is supplied with hot blast furnace exhaust gas from the blast furnace through the supply pipe 12, and reheats the exhaust gas with combustion gas and air supplied from the outside to generate drying hot air at a predetermined temperature. Here, the flow rate control of the hot air furnace exhaust gas supplied to the hot air generating furnace 13 is performed by controlling the flow rate control valve 21 installed in the supply pipe 12 and the flow rate controller 23 to which the detection signal of the flow rate detector 22 is supplied. It is controlled by the output, and the target setting value of the flow rate controller 23 is changed by a setting signal from the arithmetic processing device 50, which will be described later.

In addition, the control of combustion gas and combustion air is
These pressure controls are performed by controlling pressure control valves 28 and 29 by pressure regulators 26 and 27 supplied with the detected values of pressure detectors 24 and 25, respectively, and the flow rate control is performed by controlling the pressure control valves 28 and 29. The control output of the temperature controller 31, which is supplied with the detection signal of the temperature detector 30 that detects the temperature at the inlet side of the dryer 5, is supplied to the ratio distributor 31a, whereby the distribution control output is distributed at a constant ratio. Temperature control is carried out by flow control valves 32 and 33 supplied with It is changed and cascade controlled by a total of 35 control signals.

On the other hand, the flow rate control of cold air passing through the outside air suction pipe 14 connected between the hot air generating furnace 13 and the coal crushing dryer 5 is controlled by the detection signal of the flow rate detector 36 and the setting signal from the arithmetic processing unit 50 described later. This is done by controlling the flow rate control valve 38, which also serves as a cold air damper, by a control signal from the flow rate regulator 37.

Further, the opening degree of the suction damper 11 interposed between the blower 6 and the bag filter 8 is supplied with a detection signal from a pressure detector 40 that detects the pressure on the inlet side of the coal pulverizer dryer 5, and the calculation will be described later. It is controlled by a control signal from a pressure regulator 41 to which a set value control signal of the processing device 50 is supplied.

A temperature detection signal from a temperature detector 42 that detects the temperature on the outlet side of the bag filter 8 and a humidity detection signal from a humidity detector 44 that detects the humidity on the outlet side of the bag filter 8 are respectively supplied to the processing unit 50. The processing unit 50 outputs opening/closing control signals for opening and closing the hot air damper 15 and cold air damper 16, and control signals for changing the set values of the flow rate regulators 23, 37 and the pressure regulator 41.

Here, the arithmetic processing device 50 is composed of, for example, a microcomputer, and executes arithmetic processing according to a predetermined processing program based on a startup signal, a control signal from the temperature detector 42, and a humidity detection signal from the humidity detector 44. The temperature is automatically controlled while preventing dew condensation on the bag filter 8 and the like during the temperature rising process from the start of the pulverized coal manufacturing equipment until it reaches a predetermined set temperature.

That is, when a start signal for the pulverized coal manufacturing apparatus is input, execution of the temperature raising process shown in FIG. 2 is started.

First, in step, the coal pulverizer dryer 5 is started, and then in step it is determined whether the interlock is good or not. If the interlock is not ready,
It waits until the interlock state is reached, and when the interlock becomes good, it moves to step.

In this step, the hot air damper 15 and the cold air damper 16 are controlled to be open, and the suction damper 11 is controlled to be closed.

Next, the process moves to step to determine whether the interlock for starting the blower 6 is good or bad, and if the interlock is in a good state as described above, the process moves to step to start the bug filter 7 and the blower 6.

Next, the process moves to the step where the hot air generating furnace 1
The supply pressure of air and combustion gas to 3 is automatically controlled by pressure regulators 26 and 27 so that it is in the state necessary for combustion, and the temperature at the outlet side of coal pulverizer dryer 5 is controlled by a temperature sensor 34. The cascade control of the temperature controller 31 by the temperature controller ₃₅ is turned off based on Activate peripherals.

Next, the process moves to the step where the hot air generating furnace 1
It is determined whether or not the ignition conditions of step 3 are in place, and if the ignition conditions are not in place, the process waits until the ignition conditions are in place, and if the ignition conditions are in place, the process proceeds to step
The ignition work of the hot air generating furnace 13 begins.

Next, the process moves to step, where the cold air flow rate control valve 38, which also serves as a cold air damper, is fully opened, and the hot air furnace exhaust gas control valve 21 is set to a predetermined opening degree.

Next, the process moves to step, in which a step-shaped control signal is sent from the temperature controller 31 to the combustion gas and air flow rate control valves 32, based on the detection signal of the temperature detector 30 that detects the temperature on the inlet side of the coal pulverizer/dryer 5.
33, and accordingly, the amount of fuel gas and air supplied to the hot air generating furnace 13 is increased in steps, thereby increasing the temperature at the inlet side of the coal crushing dryer 5. At this time, the relative humidity on the outlet side of the bag filter 8 is detected by the humidity detector 44, and the relative humidity is detected by the humidity detector 44.
The ratio of hot air furnace exhaust gas to cold air is calculated so that the ratio is maintained at less than 100%, and the flow rate of each flow rate controller 23, 37 and the opening degree of the hot air damper 15 are adjusted accordingly to prevent dew condensation in the air flow transport path. control so that it does not occur.

Next, proceeding to step, it is determined whether the temperature on the outlet side of the bag filter 8 has exceeded the dew point,
If the dew point temperature has not been exceeded, the process waits until the dew point temperature has been exceeded, and when the dew point temperature has been exceeded, the process moves to step.

In this step, the hot blast furnace exhaust gas flow rate is automatically controlled by changing the set value of the flow rate controller 23 to a predetermined set value Q _s , and the set value of the pressure regulator 41 is changed to a normal operating state lower than the set value PS _1. (Pulverized coal transportation state) pressure PS ₂ is set to automatically control the inlet side pressure of the coal crushing dryer 5.

Next, the process moves to step, and it is determined whether the temperature on the outlet side of the coal pulverizer/dryer 5 has reached a set temperature (for example, 90° C.). At this time, when the outlet side temperature of the bag filter 8 is lower than the set temperature,
Combustion continues until the set temperature is reached, and when the set temperature is reached, the process moves to step.

In this step, a control signal from the temperature controller 35, which is supplied with a temperature detection signal from the temperature detector 34 that detects the temperature at the outlet side of the coal pulverizer/dryer 5, is supplied to the temperature controller 31 to start cascade control. Next, the process moves to step, where a command signal to start feeding coking coal to the coal pulverizer/dryer 5 is output, and the coking coal from the raw material tank 1 is fed through the feeding conveyor 2, the coal feed bin 3, and the chain feeder 4, and then the coal is fed into the coal grinding/drying machine 5. Supply to the crushing dryer 5 is started.

Next, the automatic temperature raising method in the above-mentioned pulverized coal manufacturing equipment will be explained in detail with reference to FIGS. 2 and 3.

First, when a starting signal for the pulverized coal manufacturing apparatus is supplied to the arithmetic processing unit 50, the coal pulverizing dryer 5 is started based on this signal (step), and then the quality of the interlock is determined (step). At this time, if it is not in the interlock state, the system waits until it becomes the interlock state, and when it becomes the interlock state, the hot air damper 15 and the cold air damper 16 are opened, and the suction damper 11 is closed (step). In this state, the blower 6 has not yet been started and the suction damper 1 has not yet been activated.
1 is in the closed state, the pressure in the pulverized coal production system consisting of the hot air generating furnace 13, the coal crushing dryer 5, the cyclone 7, the bag filter 8, and the blower 6 is maintained at approximately atmospheric pressure.

In this state, it is determined whether the starting interlock of the blower 6 is good or not (step), and when the interlock is established, the bug filter 8 and the blower 6 are started (step).

Next, the pressures of the air and combustion gas supplied to the hot air generating furnace 13 are automatically controlled to predetermined set values by the pressure regulators 26 and 27, and the inlet side pressure PI of the coal pulverizer dryer 5 is controlled by the third As _shown in FIG. 5. Start up the peripheral devices (step).
Therefore, the pressure controller 41 controls the coal crushing dryer 5.
The difference value between the detection signal of the pressure detector 40 provided on the inlet side and the target value is calculated, and this is supplied as a control signal to the suction damper 11 to adjust the opening degree of the damper. That is, when the detection signal of the pressure detector 40 falls below the target value, the damper opening degree is reduced to reduce the amount of air sucked by the blower 6 to increase the pressure on the inlet side of the coal crushing dryer 5.
Conversely, when the detection signal of the pressure detector 40 rises above the target value, the damper opening degree is increased and the blower 6
The inlet pressure of the coal pulverizer/dryer 5 is maintained at the target pressure _PS1 by increasing the suction air amount to lower the pressure at the inlet of the coal pulverizer/dryer 5.

Next, it is determined whether the ignition conditions for the hot air generating furnace 13 have been established (step), and when the ignition conditions have been established, the combustion gas being supplied to the hot air generating furnace 13 is ignited (step).

At this point of ignition, the target value of the flow rate controller 37 that adjusts the amount of cold air is set to the maximum.
The flow rate control valve 38 is fully opened, and the target value of the flow rate controller 23, which adjusts the air volume of the hot blast furnace exhaust gas, is set to the minimum value Qmin at which the air volume is small (step). Accordingly, the cold air supply pipe 1
The amount of cold air supplied to the coal pulverizer/dryer 5 through 4 becomes the maximum as shown in FIG. 3b, and the amount of hot air exhaust gas becomes the minimum as shown in FIG. 3c. Then, this hot blast furnace exhaust gas is reheated by combustion of relatively small flow rate of combustion gas as shown in FIG. 3d, which is supplied to the hot blast furnace 13, and then,
The coal is mixed with cold air and supplied to the coal crushing dryer 5. At this time, the mixing ratio of the reheated hot air exhaust gas and the cold air is much higher for the cold air, and therefore,
As shown in FIG. 3e, the rate of temperature increase in the coal pulverizer/dryer 5 becomes gradual, and the temperature at the outlet of the bag filter 8 also rises gradually.

Thereafter, while monitoring the temperature and humidity at the outlet side of the bag filter 8 with the temperature detector 42 and the humidity detector 44, the arithmetic processing unit 50 controls the temperature and humidity of the hot air furnace exhaust gas and the cold air so that the relative humidity is maintained below 100%. Calculate the mixing ratio and adjust the flow rate controller 2 accordingly.
While changing the target values 3 and 37 as appropriate, the amount of cold air is gradually decreased, and the amount of hot air exhaust gas is increased.

At the same time, the flow rate of the combustion gas supplied to the hot blast furnace 13 is increased in steps as shown in FIG. By increasing the temperature of the mixed gas of the coal crushing dryer 5 and the cold air, the temperature on the outlet side of the coal crushing dryer 5 is gradually increased as shown in FIG. 3e, and the temperature on the outlet side of the bag filter 8 is gradually increased as shown in FIG. 3a. to rise to.

In this way, when the temperature on the outlet side of the bag filter 8 gradually rises and exceeds the dew point of the hot air furnace exhaust gas, at the time _t1 when the dew point is exceeded, the cold air volume is changed to the third
As shown in FIG. 3B, the flow rate control valve 38 is fully closed and controlled to zero, and the flow rate control valve 21 is controlled to the opening degree set in the normal operating state, as shown in FIG. The flow rate is controlled, and the target value of the pressure regulator 41 is changed so that the pressure on the inlet side of the coal crushing dryer 5 becomes the pressure PS ₂ in the normal state for transporting pulverized coal, which is lower than the pressure PS ₁ , and thereby , the opening degree of the suction damper 11 is largely adjusted to create a negative pressure sufficient to pneumatically transport the pulverized coal produced by the coal crushing dryer 5 by the suction air flow by the blower 6.

At this time, the amount of combustion gas and the amount of air supplied to the hot air generating furnace 13 continue to increase in a stepwise manner as shown in FIG. continue.

Then, it is determined (step) whether the outlet temperature of the coal pulverizer/dryer 5 has reached a predetermined set value (for example, 90°C), and when the set temperature is reached, the temperature controller ₃₁ indicates that the coal Cascade control is started by supplying a control signal to a temperature controller 35 to which a detection signal from a temperature detector 34 provided on the outlet side of the coal crusher/dryer 5 is supplied, and the outlet side temperature of the coal crusher/drier 5 is set to a predetermined value. The temperature is maintained at the set temperature (step), and then a temperature increase end signal is outputted to enable feeding of the coking coal cut from the raw material tank 1 into the coal pulverizer/dryer 5 (step). The raw coal cut out from the raw material tank 1 is fed into a conveyor 2, a coal feed bin 3, and a chain feeder 4.
The production of pulverized coal is started by starting to input the coal through the pulverized coal.

The pulverized coal produced in this coal dryer 5 is supplied to a cyclone 7 by the suction force of a blower 6, and in this cyclone 7, the pulverized coal and air are centrifugally separated, and the pulverized coal is covered with pulverized coal in a blast furnace or the like. It is supplied to the supply device 9. Further, the airflow containing fine pulverized coal discharged from the cyclone 7 is supplied to the bag filter 8, collected by the filter cloth, and supplied to the pulverized coal supply device 9 in the same manner as described above.

In the above embodiment, the inlet pressure of the coal pulverizer dryer 5 was compared with the pressure in the normal state from the time of ignition in the hot air generating furnace 13 until the outlet temperature of the bag filter 8 reached the dew point of the hot air exhaust gas. Although the case where the pressure is controlled to be high has been described, it is not limited to this, and at least the hot air generating furnace 1
In order to easily and reliably ignite only at the time of ignition in step 3, the pressure may be set to a relatively high level, and after ignition is confirmed, the pressure may be set to a normal, relatively low pressure.

Further, in the above embodiment, a case has been described in which the control in the temperature rising process is performed by the arithmetic processing unit 50 using a microcomputer, but the invention is not limited to this. It is also possible to configure an arithmetic processing device by combining circuits.

〔Effect of the invention〕

As explained above, according to the present invention, the pressure on the inlet side of the coal crushing dryer is made higher than the pressure in the normal operating state when the hot air generating furnace is ignited, thereby easily and reliably igniting the fuel in the hot air generating furnace. At the same time, until the outlet temperature of the bag filter reaches the dew point of the hot air exhaust gas, the ratio of cold air to the hot blast furnace exhaust gas is gradually lowered while monitoring the bag filter outlet temperature and humidity to prevent dew condensation on the pulverized coal transport route and the bag filter. Moreover, since a series of controls during the temperature raising process are performed automatically, it is possible to reduce the burden on the operator during the temperature raising process, and eliminate problems such as operational errors. Furthermore, the ratio of cold air and hot blast furnace exhaust gas is controlled while monitoring the temperature and humidity at the exit side of the bag filter.
This has the effect of shortening the heating time while preventing dew condensation.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the present invention, Fig. 2 is a flowchart showing the processing procedure of an arithmetic processing unit applicable to this invention, and Fig. 3 is a waveform of each part used to explain the operation of this invention. FIG. 4 is a system diagram showing a conventional example. In the figure, 1 is a raw material tank, 5 is a coal crushing dryer, 6 is a blower, 7 is a cyclone, 8 is a bag filter, 9
is a pulverized coal feeding device, 11 is a suction damper,
13 is a hot air generating furnace, 23 is a hot air furnace exhaust gas flow rate controller, 31 is a temperature controller for fuel supply control, 35 is a temperature controller for cascade control, 37 is a cold air flow rate controller, 41 is a coal crushing dryer inlet pressure adjustment Total, 50
is an arithmetic processing unit.

Claims (1)

[Claims] 1. A coal pulverizer/dryer that pulverizes and dries raw coal to produce pulverized coal; a hot air generating furnace that supplies drying hot air made by reheating hot blast furnace exhaust gas to the coal pulverizer/dryer;
In a pulverized coal manufacturing apparatus that includes a blower for generating a transport air flow connected to the coal pulverizing dryer through a pulverized coal separator and collector including a bag filter, the hot air furnace exhaust gas reaches the dew point during the temperature rising process at startup. Until the dew point is reached, the ratio of cold air to the hot blast furnace exhaust gas is gradually lowered while monitoring the outlet temperature and humidity of the bag filter, and the temperature control operation amount is increased in steps to prevent condensation. The automatic heating of a pulverized coal manufacturing apparatus is characterized in that the temperature is raised using only hot blast furnace exhaust gas until the temperature is reached, and when the set temperature is reached, the outlet temperature control of the coal pulverizer and dryer is automatically started. Drying method.