JP7056399B2 - Coal temperature control method - Google Patents

Description

The present invention relates to a method for appropriately controlling the coal temperature of dry coal that is dried in a drying facility, transported to a coal storage tank, and stored.

In general, if a large amount of coal is deposited or stored for a long period of time, it may spontaneously ignite. Therefore, many techniques for predicting or preventing spontaneous combustion of coal have been proposed (for example, patent documents). See 1-5).

In the process of charging coal into a coke oven to produce coke for a blast furnace, the coal is dried to reduce the adhering water content to, for example, about 6% or less in order to improve coke quality and productivity. (Dry coal) is temporarily stored in a coal storage tank in front of the coke oven, but the risk of spontaneous ignition cannot be avoided in the coal storage tank.

FIG. 1 schematically shows one aspect of the process from the drying equipment of the conventional coke manufacturing process to the coke oven. Coal is supplied from a coal hopper (not shown) to a drying facility 1 (for example, a fluidized bed drying facility for drying coal by flowing it with warm air [Patent Document 6, see]) and dried.

The dried coal (dried coal) is transported to the coal storage tank 3 by the belt conveyor 2 and stored, and is appropriately charged from the coal storage tank 3 to the coke oven 4. The coke produced in the coke oven 4 is cooled by a fire extinguishing system (not shown) and transported to a blast furnace (not shown).

Normally, in order to prevent spontaneous combustion of the dry coal stored in the coal storage tank 3, the drying facility 1 is set so that the coal temperature of the dry coal stored in the coal storage tank 3 is lower than the control temperature (for example, 60 ° C.). The coal temperature of the dried coal discharged from the coal is measured by a non-contact thermometer 5 (for example, a radiation thermometer) arranged in the upper part of the drying facility 1 side of the conveyor 2 and managed in the central control room.

The coal temperature of the dry coal discharged from the drying facility 1 to the conveyor 2 decreases during transportation, but even if the temperature decreases, the coal temperature of the dry coal stored in the coal storage tank 3 remains at the control temperature (for example, 60 ° C.). ) Is likely to be exceeded, the coal cooling device 6 (for example, a sprinkler) provided in the upper part of the drying facility 1 side of the conveyor 2 is operated by the command of the central control room to cool the dried coal.

Further, in the coal storage tank 3, the temperature of the stored dry coal (stored coal) is measured by the in-tank thermometer 7, and when the coal temperature rises and exceeds the control temperature, the coal storage tank is instructed by the central control room. The coal cooling device 8 (for example, a sprinkler) provided in 3 is operated to cool the stored coal.

With the growing awareness of coal disaster prevention in coke production in recent years, it is necessary to strengthen the temperature control of humidity control and dry coal stored in the coal storage tank 3 in order to prevent spontaneous combustion of coal.

Japanese Unexamined Patent Publication No. 58-026723 Japanese Unexamined Patent Publication No. 08-067315 Japanese Unexamined Patent Publication No. 08-08472 JP-A-2015-132575 JP-A-2017-090286 Japanese Unexamined Patent Publication No. 2001-055582

When humidity-controlled and dry coal is used as coal for coke production, it is necessary to strengthen the temperature control of the dry coal stored in the coal storage tank in order to prevent spontaneous combustion. There is.

(a) The operating temperature of the sprinkler that cools the dried coal during transportation is empirically set based on the operation results, and the seasonal difference in the outside air temperature and the composition difference of the transportation equipment (conveyor captain and dehumidifying cooling device). Since the influence on the coal temperature (presence or absence, etc.) is not taken into consideration, the coal temperature of the dry coal transported and stored in the coal storage tank is not properly controlled.

(b) It is not possible to properly determine the operating temperature of the sprinkler that cools the dry coal being transported when there is no operational record or when a new thermometer for measuring the coal temperature is installed.

(c) In the summer when the coal temperature constantly exceeds the operating temperature of the sprinkler, the sprinkler will continue to operate, and it will be difficult to properly manage the water content of the stored coal.

Therefore, in the present invention, in consideration of the influence of the seasonal difference in the outside air temperature and the composition difference of the transport facility on the coal temperature of the dry coal being transported, the dry coal is transported to the coal storage facility and stored. It is an object of the present invention to appropriately control the coal temperature of dry coal until the time of coal firing, and to reduce the risk of spontaneous combustion, and an object of the present invention is to provide a method for controlling the temperature of coal to solve the problem.

The present inventors have diligently studied a method for solving the above problems. As a result, if the coal temperature is managed in the dry coal transport path based on the controlled coal temperature reasonably estimated in consideration of the influence of the seasonal difference in the outside air temperature and the composition difference of the transport equipment, the coal storage tank can be used. It was found that the coal temperature of the dry coal to be transported and stored can be appropriately controlled, and the risk of spontaneous combustion of the dry coal in the coal storage tank can be significantly reduced. This point will be described later.

The present invention has been made based on the above findings, and the gist thereof is as follows.

(1) A method of controlling the coal temperature when dried coal dried by a drying facility is transported to a coal storage tank equipped with a coal cooling device and stored in a transport path equipped with a coal cooling device.
(I) A plurality of measurement positions for measuring the coal temperature of the dry coal being transported are set in the above transport path.
(Ii-1) Based on the coal temperature and outside air temperature measured at the measurement position, the transport time of the dry coal to the measurement position, and the overall heat transfer coefficient of the dry coal, the dry coal passing through the measurement position Estimate the controlled coal temperature, which is the upper limit of the coal temperature,
(Ii-2) The temperature of coal characterized by operating a coal cooling device appropriately based on the above-mentioned controlled coal temperature and controlling the coal temperature until the dry coal is transported to the coal storage tank and stored. Management method.

(2) The method for controlling the temperature of coal according to (1) above , wherein the coal cooling device is a sprinkler and / or a dehumidifying cooling device .

(3) The control coal temperature of dry coal passing through the i (= 1 to n) th measurement position set in the transport path: Ti (° C.) is estimated by the following formula (1). Or the method for controlling the temperature of coal according to (2).
Ti = (Ts-To) ・ e- ^{C ・ t} + To
Ts: Coal temperature (° C) of dried coal immediately after being discharged from the drying equipment
To: Outside air temperature (° C) around dry coal
C: Integrated heat transfer coefficient of dry coal (W / m ² · K)
t: Transport time of dried coal from the drying equipment to the i-th measurement position (minutes)

(4) When the coal cooling device is a dehumidifying cooling device, the transport time t is the transport time (t ₀ ) from the drying facility to the i-th measurement position, depending on the number of dehumidifying cooling devices used. The method for controlling a temperature of coal according to (3) above, wherein a transport time (t ₀ + t') corrected by adding a required time (t' ) is used.

(5) When the coal temperature of the dry coal measured at the measurement position exceeds the controlled coal temperature, the coal cooling device provided in the transport path is automatically operated, or the coal cooling device is manually operated . The method for controlling the temperature of coal according to any one of (1) to (4) above.

(6) When the coal temperature of the dry coal stored in the coal storage tank exceeds 60 ° C. of the controlled coal temperature, the coal cooling device provided in the coal storage tank is automatically operated, or the coal cooling device is operated. The method for controlling the temperature of coal according to any one of (1) to (5) above, which comprises manually operating the coal.

According to the present invention, when transporting and storing dry coal to a coal storage facility, the coal cooling device provided in the transport path and / or the coal storage facility is appropriately operated to keep the coal temperature of the dry coal below the controlled coal temperature. In addition, even if there is a change in the seasonal difference in the outside air temperature or the configuration difference in the transport equipment, the controlled coal temperature can be changed as appropriate to keep the coal temperature of the dry coal below the controlled coal temperature. , The risk of spontaneous ignition can be significantly reduced.

Further, according to the present invention, when the coal temperature constantly exceeds the controlled coal temperature in the summer and the sprinkler must be continuously used as the coal cooling device, cooling by the dehumidifying cooling device is appropriately performed. This can reduce the frequency of watering and avoid an excessive increase in the water content of the dry coal stored in the coal storage tank.

As described above, according to the present invention, the properties of the dry coal transported to the coal storage tank and / or the properties of the dry coal in the coal storage tank do not adhere to the inner wall of the coal storage tank and do not become sludge. , And properties that do not adversely affect the quality of coke can be ensured.

It is a figure which shows typically one aspect of the process from the drying equipment to the coke oven in the conventional coke manufacturing process. It is a figure which shows typically one aspect which applied this invention to the process from a drying facility to a coke oven in a coke manufacturing process. It is a figure which shows the relationship between the transport distance from a drying facility, and the coal temperature.

The method for controlling the temperature of coal of the present invention (hereinafter, may be referred to as "the method for controlling the temperature of the present invention") is a method for storing dried coal dried in a drying facility in a transport path provided with a coal cooling device and equipped with a coal cooling device. It is a method of controlling the coal temperature when it is transported to a tank and stored.
(I) A plurality of measurement positions for measuring the coal temperature of the dry coal being transported are set in the above transport path.
(Ii-1) Based on the coal temperature and outside air temperature measured at the measurement position, the transport time of the dry coal to the measurement position, and the integrated heat transfer coefficient of the dry coal, the dry coal passing through the measurement position Estimate the controlled coal temperature, which is the upper limit of the coal temperature,
(Ii-2) The coal cooling device is appropriately operated based on the above-mentioned controlled coal temperature, and the coal temperature is controlled until the dry coal is transported to the coal storage tank and stored.

That is, the temperature control method of the present invention is estimated based on the coal temperature and the outside air temperature measured at the measurement position of the dry coal transport path, the transport time of the dry coal to the measurement position, and the integrated heat transfer coefficient of the dry coal. Based on the "upper limit of coal temperature of dry coal passing through the measurement position: controlled coal temperature", the basic idea is to control the coal temperature until the dry coal is transported to the coal storage tank and stored. do.

Hereinafter, the temperature control method of the present invention will be described on the premise of transporting and storing dry coal in the coke manufacturing process. However, since the temperature control method of the present invention is based on the above basic idea, the coke manufacturing process. Not limited to this, it can be applied to other manufacturing processes including a process of transporting and storing dried coal.

First, the estimation of the controlled coal temperature will be described.

As described above, in the prior art, (a) the operating temperature of the sprinkler that cools the dried coal during transportation is empirically set from the operation results, and the seasonal difference in the outside air temperature and the composition difference of the transportation equipment. Since the influence on the coal temperature (conveyor captain, presence / absence of dehumidifying cooling device, etc.) is not taken into consideration, the problem is that the coal temperature of the dry coal transported and stored in the coal storage tank is not properly controlled. There is.

Therefore, the present inventors appropriately control the coal temperature of the dry coal transported and stored in the coal storage tank, that is, the operating temperature of the sprinkler (coal cooling device) for cooling the dried coal being transported, that is, The idea is to reasonably estimate the upper limit of the coal temperature in consideration of the influence of the seasonal difference in the outside air temperature and the composition difference of the transport equipment on the coal temperature, and the "upper limit of the coal temperature" related to the estimation is set to coal. The coal temperature of dry coal transported and stored in the storage tank was introduced as an index to control the coal temperature at appropriate points on the transport path: "controlled coal temperature". This point is a feature of the temperature control method of the present invention.

The controlled coal temperature is based on Fourier's law, taking into consideration the influence of the seasonal difference in the outside air temperature and the configuration difference of the transport equipment (conveyor length, presence / absence of dehumidifying cooling device (coal cooling device), etc.) on the coal temperature. Estimate using the following formula derived (hereinafter sometimes referred to as "estimation formula").
Ti = (Ts-To) ・ e- ^{C ・ t} + To
Ts: Coal temperature (° C) of dried coal immediately after being discharged from the drying equipment
To: Outside air temperature (° C) around dry coal
C: Overall heat transfer coefficient of dry coal (W / m ²・ K)
t: Transport time of dried coal from the drying equipment to the i-th measurement position (minutes)

Ti (° C.) is the controlled coal temperature of the dry coal passing through the i (= 1 to n) th measurement position appropriately set in the transport path. In the above estimation formula, the outside air temperature around the dry coal and the transport time of the dry coal from the drying facility to the i-th measurement position (= length of the transport path from the drying facility to the i-th measurement position / transport). By introducing the velocity) as the parameters To (° C.) and t (minutes), respectively, the seasonal difference in the outside air temperature and the configuration difference in the transport equipment are taken into consideration.

By adopting the controlled coal temperature to control the coal temperature of the dry coal being transported, (b) in the conventional technology, when there is no operation record or when a new thermometer for measuring the coal temperature is installed, the coal is being transported. The problem is that the operating temperature of the sprinkler (coal cooling device) that cools the dry coal cannot be properly determined, and (c) in the summer when the coal temperature constantly exceeds the operating temperature of the sprinkler. At the same time, the problem that the watering device will be continuously operated and it will be difficult to properly manage the water content of the stored coal can be solved.

Specifically, in the temperature control method of the present invention, in order to keep the coal temperature of the dry coal stored in the coal storage tank at 60 ° C. or lower, the coal temperature of the dry coal measured at the measurement position set in the transport path is the measurement. When the controlled coal temperature calculated by the above estimation formula at the position is exceeded, the coal cooling device (sprinkler and / or dehumidifying cooling device) arranged in the transport path is automatically or manually operated.

Here, FIG. 2 schematically shows an aspect in which the temperature control method of the present invention is applied to the process from the drying equipment to the coke oven in the coke manufacturing process.

In the transport path composed of the belt conveyor 2 for transporting the dried coal discharged from the drying facility 1 to the coal storage tank 3, the number of measurement positions for measuring the coal temperature of the transported dry coal is an appropriate number (1 to n). It is set.

A non-contact thermometer 5 is arranged at the first measurement position close to the drying facility 1, a coal cooling device 6 (i = 1) is arranged close to the measurement position, and the end of the transport path is further arranged. A non-contact thermometer 5i (i = 2 to n) is placed at the second and subsequent measurement positions, and a coal cooling device 6i (i = 2 to n) is placed close to the measurement position. There is. Further, a dehumidifying / cooling device 9 is arranged in the middle of the transport path.

The number of measurement positions set in the transport path and the number of coal cooling devices placed close to the measurement positions are set from the drying equipment to coal so that the coal temperature of the dry coal can be efficiently controlled. Depending on the length of the transport path to the storage tank (conveyor length), the distance between adjacent coal cooling devices should be appropriately secured so that the coal temperature can be effectively lowered.

As the thermometer for measuring the coal temperature of the dry coal being transported, a non-contact thermometer (for example, a radiation thermometer) is preferable in consideration of wear deterioration due to the transported coal, equipment inspection efficiency, and the like.

Then, in the transport path, the coal temperature of the dry coal passing through the measurement position is measured by the non-contact thermometers 5, 5i and 5n, and when the coal temperature exceeds the controlled coal temperature at the measurement position, the measurement position is reached. The coal cooling devices 6, 6i, 6n arranged in close proximity to the coal, and the dehumidifying cooling device 9 as appropriate, are operated automatically or manually, for example, at the command of the central control room to produce dry coal. Cool and bring the coal temperature below the controlled coal temperature.

In this way, the coal temperature of the dry coal being transported is controlled so that the coal temperature of the dry coal transported and stored in the coal storage tank 3 is finally equal to or lower than the controlled coal temperature (for example, 60 ° C.). ..

Even if the coal temperature of dry coal drops during transportation, when the coal is stored in the coal storage tank, the coal temperature exceeds the control temperature (for example, 60 ° C.), or the coal temperature rises in the coal storage tank. When the controlled temperature is exceeded, the coal cooling device 8 provided in the coal storage tank is operated, for example, according to a command from the central control room to cool the dry coal.

The coal cooling device may have a cooling function for lowering the coal temperature of the dry coal, and is not particularly limited to a specific cooling device. A dehumidifying cooling device that removes and cools the coal is preferable, and these devices are used in combination as appropriate so that the cooling efficiency of the dry coal can be improved and the coal temperature can be efficiently controlled during the transportation of the dry coal. ..

When using a sprinkler as a coal cooling device, sprinkle water during transportation of dry coal so that the water content of the dry coal stored in the coal storage tank does not exceed the specified value (for example, 6%) and the coke quality does not deteriorate. It is necessary to adjust the total amount of water sprinkled.

When the dehumidifying cooling device is used as the coal cooling device, the transport time (t) in the above estimation formula is the transport time corrected by the time (minutes) passing through the dehumidifying cooling device. For example, the required time (t') is added to the transfer time (t0) according to the number of dehumidifying / cooling devices used to the transfer time (t0) from the drying equipment to the i-th measurement position , and this addition is used. The corrected transport time (t0 + t') is used as the transport time (t) in the above equation.

Next, an example of the present invention will be described. The conditions in the examples are one condition example adopted for confirming the feasibility and effect of the present invention, and the present invention is based on this one condition example. Not limited. The present invention can adopt various conditions as long as the gist of the present invention is not deviated and the object of the present invention is achieved.

(Example 1)
In the actual coke manufacturing process, the temperature control method of the present invention was carried out in a transport path for transporting dried coal from the drying equipment to the coal storage tank A and the coal storage tank B.

The controlled coal temperature (Ti) at the measurement position appropriately set in the transport path is such that the coal temperature (Ts) of the dry coal immediately after being discharged from the drying facility is 90 ° C and the outside air temperature (To) is 20 ° C. The integrated heat transfer coefficient (C) was estimated according to the following estimation formula using the numerical value (W / m ² · K) obtained in the test.
Ti = (Ts-To) ・ e- ^{C ・ t} + To

In FIG. 3, the controlled coal temperature estimated by the above estimation formula is indicated by “◯”. Since dry coal is transported to coal storage tank A and coal storage tank B (positions A and B in the figure), the horizontal axis is from the drying equipment in order to clarify the relationship between the transport distance and the coal temperature. The transport distance (m) was set. From FIG. 3, when the controlled coal temperature of the dry coal stored in the coal storage tank is 60 ° C., the controlled coal temperature (〇) becomes 60 ° C. at a transport distance of 270 m, and the coal storage tank A (in the figure, A). It can be seen that the coal temperature in the position) and the coal storage tank B (position B in the figure) is less than 60 ° C. (controlled temperature).

FIG. 3 shows the transition of the coal temperature when the coal temperature of the dried coal immediately after being discharged from the drying equipment: Ts is 90 ° C. and the outside air temperature is 45 ° C. as a reference example. It can be seen that the coal temperature (x) is less than 60 ° C. in the coal storage tank B having a transport distance of more than 550 m, but exceeds 60 ° C. in the case of transporting to the coal storage tank A. In this case, when the coal is transported to the coal storage tank A, sprinkling cooling is always performed, and the water content of the dry coal stored in the coal storage tank A cannot be appropriately controlled.

FIG. 3 shows the transition of the coal temperature when the coal temperature of the dried coal immediately after being discharged from the drying equipment: Ts is 90 ° C. and the outside air temperature is 45 ° C. as an example of the invention by “Δ”. By the time the transport distance reached 200 m, the dehumidifying and cooling device was appropriately operated to cool the dried coal.

As a result, the coal temperature of the dry coal reached 60 ° C. at a transport distance of 270 m, and it was placed in both the coal storage tank A (position A in the figure) and the coal storage tank B (position B in the figure). Dry coal could be stored at a coal temperature of less than 60 ° C. without sprinkling cooling. The total transport distance corresponding to the transport time corrected by using the dehumidifying / cooling device is 200 m (20 m × 10 units).

As described above, according to the present invention, when transporting and storing dry coal to a coal storage facility, the coal cooling device provided in the transport path and / or the coal storage facility is appropriately operated to control the coal temperature of the dry coal. The coal temperature can be kept below the controlled coal temperature, and even if there is a change in the seasonal difference in the outside air temperature or the configuration difference of the transport equipment, the controlled coal temperature is changed as appropriate to keep the coal temperature of the dry coal below the controlled coal temperature. The risk of spontaneous ignition can be significantly reduced.

Further, according to the present invention, even when the coal temperature constantly exceeds the controlled coal temperature in the summer and the sprinkler must be continuously used as the coal cooling device, the cooling by the dehumidifying cooling device is appropriate. By implementing this, the frequency of watering can be reduced, and an excessive increase in the water content of the dry coal stored in the coal storage tank can be avoided.

As described above, according to the present invention, the properties of the dry coal transported to the coal storage tank and / or the properties of the dry coal in the coal storage tank do not adhere to the inner wall of the coal storage tank and do not become sludge. , And properties that do not adversely affect the quality of coke can be ensured. Therefore, the present invention has high utility in the coal industry.

1 Drying equipment 2 Belt conveyor 3 Coal storage tank 4 Coke furnace 5, 5i Non-contact thermometer 6, 6i Coal cooling device 7 In-tank thermometer 8 Coal cooling device 9 Dehumidifying cooling device

Claims (6)

It is a method of controlling the coal temperature when the dried coal dried by the drying equipment is transported to a coal storage tank equipped with a coal cooling device and stored in a transport path equipped with a coal cooling device.
(I) A plurality of measurement positions for measuring the coal temperature of the dry coal being transported are set in the above transport path.
(Ii-1) Based on the coal temperature and outside air temperature measured at the measurement position, the transport time of the dry coal to the measurement position, and the integrated heat transfer coefficient of the dry coal, the dry coal passing through the measurement position Estimate the controlled coal temperature, which is the upper limit of the coal temperature,
(Ii-2) The temperature of coal characterized by operating a coal cooling device appropriately based on the above-mentioned controlled coal temperature and controlling the coal temperature until the dry coal is transported to the coal storage tank and stored. Management method. The method for controlling the temperature of coal according to claim 1, wherein the coal cooling device is a sprinkler and / or a dehumidifying cooling device. The first or second claim, wherein the controlled coal temperature: Ti (° C.) of the dry coal passing through the i (= 1 to n) th measurement position set in the transport path is estimated by the following formula. Coal temperature control method.
Ti = (Ts-To) ・ e- ^{C ・ t} + To
Ts: Coal temperature (° C) of dried coal immediately after being discharged from the drying equipment
To: Outside air temperature (° C) around dry coal
C: Integrated heat transfer coefficient of dry coal (W / m ² · K)
t: Transport time of dried coal from the drying equipment to the i-th measurement position (minutes) When the coal cooling device is a dehumidifying cooling device, the transport time t is the transport time (t ₀ ) from the drying facility to the i-th measurement position , and the required time according to the number of dehumidifying cooling devices used. The temperature control method for coal according to claim 3 , wherein a transport time (t ₀ + t') corrected by adding (t') is used. When the coal temperature of the dry coal measured at the measurement position exceeds the controlled coal temperature, the coal cooling device provided in the transport path is automatically operated, or the coal cooling device is manually operated. The method for controlling the temperature of coal according to any one of claims 1 to 4 . When the coal temperature of the dry coal stored in the coal storage tank exceeds the controlled coal temperature of 60 ° C., the coal cooling device provided in the coal storage tank is automatically operated, or the coal cooling device is manually operated. The method for controlling the temperature of coal according to any one of claims 1 to 5 , wherein the coal is allowed to be temperature-controlled.

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