JP2003165980A - Method for adjusting water content of coal to be charged into coke oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting the water content of coal to be charged into a coke oven whereby the water content of a coal blend, which varies with season and weather, can be kept constant at the time when the blend is charged into a coke oven. <P>SOLUTION: In this method, the water content of coal to be charged into the coke oven is adjusted by using a dryer 20. Water is added to the coal blend at the inlet side of the dryer so that the water content of the blend at the outlet side of the dryer is a specified value or higher; or water is added to coal of a simple brand present at the inlet side of a blending tank 15 to be charged thereinto so as to give the coal a specified water content or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for adjusting the water content of coal charged into a coke oven.

[0002]

Coke used as a raw material for iron making is
It is produced by dry distillation of coking coal in a chamber furnace type coke oven. The flow from the arrival of the raw coal to the dry distillation in the coke oven will be described with reference to FIG. Since the quality of coke (strength, ash content, reactivity, etc.) is greatly affected by the raw material coal, multiple types of raw material coal are usually blended and dry-distilled in a coke oven. As shown in FIG. 4, the coking coal is piled up and managed in the stockyard 11 for each brand, and the required brand of coal is cut out by the reclaimer 12 and put into the blending tank 15 via the transportation conveyor 13. In the mixing tank 15, each tank contains a single coal for each brand.

Coal of various brands selected to satisfy the quality required for coke is cut out from the blending tank 15 according to the blending ratio and sent to the crusher 17 via the transport conveyor 16. Coal is crusher 17 and 3 mm or less is 7
After being crushed to be about 0 to 80%, it is sent to the dryer (humidifying coal device) 20 by the transport conveyor 18, and the water content in the coal is adjusted here. The coal discharged from the dryer 20 is sent to the coke oven 24 by the transport conveyor 21, is charged into each carbonization chamber from the coal car 23, and is subjected to the carbonization operation for about 17 to 21 hours, and then becomes coke.

In the coke oven 24, the coke oven gas generated during the carbonization of coal is discharged through the flue 25, the tar content 29 in the gas is removed by the tar decanter 28, and then the coke oven gas 27 is sent out as fuel. Used for etc.

The coal piled in the stockyard 11 is originally 8 to 13 depending on the climate of the place of origin and management conditions.
It usually contains about% by weight of water. Furthermore, since the stockyard 11 is used after being left as stock for about 2 days to 3 months, the water content varies depending on the weather and the like. Especially when there is a large amount of rainfall such as during the rainy season and during typhoons, the water content becomes as high as more than 13% by mass, and coal left in the stockyard 11 during summer when sunshine is drying and during winter when there is little rainfall. The water content in it tends to decrease. Further, there may be a large variation in the water content between the surface portion and the lower layer portion of the pile in the stockyard 11.

[0006] When these coals are cut out from the mixing tank 15 at a predetermined mixing ratio, it is necessary to correct the water content by dry conversion. Therefore, before loading into the mixing tank 15, the moisture meter 14 on the transport conveyor 13 is used. The water content is measured by the method described above, and the water content at the time of charging is representative of the water content in each mixing tank.

Coal cut out from the blending tank 15 by a predetermined amount is fed to the dryer 20 through the transport conveyor 16, the crusher 17, and the transport conveyor 18 in the state of blended coal in which a predetermined brand is mixed at a predetermined ratio. Charged. At this time, the moisture value of the coal blend is measured by the moisture meter 19 on the transport conveyor 18.

In the dryer 20, the coal is heated to about 80 to 90 ° C. to evaporate the water content in the coal, and the water content after the drying is carried out using the water content meter 31 on the transport conveyor 21 on the outlet side of the dryer 20. Measure the value. The dryer 20 adjusts the amount of heat input so that the moisture value after drying becomes a predetermined moisture value. In the example of FIG. 3, a steam source 33 using steam as a heat source is provided, and the control device 32 controls the opening degree of the steam control valve 34 by comparing and calculating the measured value of the moisture meter 31 with the target water content value. The steam 35 is supplied to adjust the moisture content of coal on the outlet side of the dryer to a predetermined value.

If the amount of water in the blended coal is large, an additional amount of carbonization heat in the coke oven is required, or the carbonization of coal may not be completed within a predetermined time.
As described above, a dryer is used to prepare a blended coal having a constant water content against the water content in the coal which fluctuates significantly. However, the adjustment of the coal moisture content using the dryer 20 has a problem that the moisture content is excessively reduced when the coal moisture content decreases due to the influence of weather or the like.

The amount of water in the blended coal at the time of charging into the coke oven 24 is preferably about 6 to 6.5% by mass. If the water content is lower than this, the bond strength between coals of the coal blend charged into the coke oven will be reduced, so that during the carbonization, fine coal coal powder will be carried along with the generated gas and transported by the tar decanter. The quality of tar deteriorates because it is mixed in. Further, similarly, the fine powder easily adheres to the furnace wall of the coke oven, and as a result, carbon generated by the thermal decomposition of the generated gas easily adheres to the furnace wall, so that the growth rate of the furnace wall carbon 26 is promoted and the coke increases. Will interfere with the extrusion. Therefore, when the water content of coal decreases in summer, winter, etc., the dryer is operated with the heat supply minimized, or the heat supply is stopped to load the coal. However, even if the heat supplied from the dryer is minimized, the drying of the coal due to the temperature rise proceeds, so that it is impossible to prevent the reduction of the water content of the coal blend. Even if the dryer is stopped, the problem cannot be solved if the amount of water in the blended coal is less than or equal to the above preferable amount, and if it is not the case, the amount of water is not controlled. The problem that the amount of dry distillation heat in the furnace fluctuates and the quality of the coke produced fluctuates is inevitable.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to maintain a constant amount of water in coal blending at the time of charging into a coke oven, with respect to the coal water which fluctuates depending on the season and weather as described above. And More specifically, it is an object of the present invention to provide a technique capable of keeping the amount of water in the coal blend charged into the coke oven constant even when the coal in the stockyard is excessively dry.

[0012]

[Means for Solving the Problems] Conventionally, when coal is dry, water is sprayed on the surface of a pile of coal in order to prevent scattering by wind in the stockyard. Only watering the surface of the pile,
It was not possible to adjust the water content of the whole pile due to the weather. The present invention earnestly studied a method capable of effectively adjusting the water content in the process of transporting coal from the stockyard to the coke oven, and developed the following means. The present invention is a method of adjusting the water content of a coal to be charged into a coke oven by using a dryer, so that the water content in the coal at the outlet side of the dryer becomes a predetermined value, and the coal blended at the inlet side of the dryer. Is a method for adjusting the water content of coal for charging into a coke oven, which is characterized in that water is added to the coal.

A second aspect of the present invention is a method for adjusting the water content of a coal to be charged into a coke oven by using a drier, in which coal of a single brand of coal to be charged into a blending tank is used. Is a method for adjusting the water content of the coal for charging into the coke oven, wherein water is added to the coal on the inlet side of the blending tank so that the water content of the coal becomes a predetermined value.

Further, a third aspect of the present invention is a method for adjusting the water content of the coal charged into the coke oven by using a dryer so that the water content of the coal on the outlet side of the dryer becomes a predetermined value. Is a method for adjusting the water content of coal for charging into a coke oven, characterized in that water is added to a single brand of coal charged into a blending tank.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention is to add water to blended coal on the inlet side of the dryer so that the water content in the coal on the outlet side of the dryer becomes a predetermined value. In conventional dryer control, the amount of heat supplied to the dryer is changed so that the moisture value detected by the moisture meter on the dryer outlet side is below the target upper limit. At that time, the heat supply amount becomes the minimum. Here, when the water content further decreases, the problem of excessive drying of coal as described above occurs.

Therefore, as shown in FIG. 1, the moisture meter 31
When the moisture value measured in step 1 is smaller than the moisture value which is the minimum amount of heat supply to the dryer 20, and is less than the reference value, water is transferred onto the transport conveyor 18 on the dryer entrance side. Disperse. That is, the water source 42 is provided and a signal from the moisture meter 31 on the dryer outlet side conveyor is sent to the controller 41.
Then, the controller 41 adjusts the amount of water supplied from the water source 42 by the adjusting valve 43, discharges it from the water spray 44, and adds water to the coal on the transport conveyor 18. As a result, it is possible to increase the amount of water in the coal at the inlet of the dryer 20, and even if the amount of heat supplied by the dryer 20 is the minimum, the water content of the coal on the outgoing side is not less than a predetermined value. Can be held at. At this time, the reference value for stopping the water spray is larger than the reference value for starting the water spray, and is smaller than the water content value that is the minimum heat supply amount to the dryer, so that the conventional dryer The coal moisture value on the outlet side of the dryer can be maintained at a predetermined value without interfering with the heat supply control.

Further, in the second aspect of the present invention, water is added to coal on the inlet side of the blending tank so that the water content in the coal of the single brand coal charged into the blending tank becomes a predetermined value. Figure 2 is this second
2 is a flow sheet of the method invention of FIG. The water content of coal piled up in stockyards varies depending on the origin and properties of the coal (grain size, grain shape, pores, etc.). Therefore, by controlling the water content of a specific coal brand, it is possible to maintain the water content of all coals to be blended to a certain level or above, thereby properly controlling the water content control function of conventional dryers. Can be held. In the present invention, the control device 51 controls the amount of water supplied from the water source 52 so that the measured value of the moisture meter 14 matches the target value.
3. Supply through the sprinkler 54. While the reclaimer 12 is transporting coal of a predetermined brand placed on the transport conveyor 13 to the blending tank 15, water is sprayed onto the transport conveyor 13 according to the measurement value of the moisture meter 14. The target value of the water content at this time may be set so that the water content can be properly adjusted in the dryer, and this can be controlled as a predetermined value.

Further, in the third aspect of the present invention, water is added to the single brand coal charged into the blending tank so that the water content in the coal on the dryer outlet side becomes a predetermined value. FIG. 3 is a flow sheet of the third method invention.

In the present invention, the moisture content of the coal on the outlet side of the dryer is measured by the moisture content meter 31. Therefore, when this value is less than a predetermined value, the control device 61 controls the unit of the single brand sent to the blending tank. Water the coal to ensure proper moisture control in the dryer. That is, the control device 61 compares the measured value of the water content meter 31 with the target water content value of the coal charged in the coke oven, and adjusts the amount of water supplied from the water source 52 so as to match the target water content value. It is supplied through the sprinkler 54.

It is preferable that the single brand coal to be sprinkled here be transported at the time of transportation of a brand brand having a low water content since the water content of the coal after blending tends to be uniform. It doesn't have to be. That is, moisture may be added to the coal being transported to the blending tank at the timing of performing moisture measurement on the dryer outlet side.

The target value to be compared with the water content measured by the water content meter 31 at this time is the same as in the first invention, and the water content value measured by the water content meter 31 is the minimum heat supply amount to the dryer 20. A value smaller than the water content value that satisfies the above condition may be used as the reference value. Thereby, the water content of the coal charged into the coke oven can be set to a predetermined value with this reference value as a predetermined value.

In any of the above inventions, an infrared moisture meter, a gamma ray moisture meter, or the like can be appropriately selected as the moisture meter. The infrared moisture meter that has been used conventionally is simple and suitable in terms of maintenance.

As a water sprinkling mechanism, a running water channel is formed from a water source such as a pump or a tank onto a transportation conveyor by pipes or hoses.
Conventional means such as providing a watering nozzle at the tip can be used. By installing a control valve in the middle of this water flow path and providing a control device that outputs the control valve opening to the actuator of the control valve by comparing the measured value of the moisture meter with the set value, the sprinkling amount can be easily controlled. can do.

[0024]

Example 1 A control method of adding water to the blended coal on the inlet side of the dryer was carried out so that the moisture content of the coal on the outlet side of the dryer shown in FIG. 1 exceeded a predetermined value. The dryer is a tube dryer type, and while rotating an inclined cylindrical dryer around the center axis of the cylinder, the steam is circulated through a steam pipe arranged parallel to the axis into the cylindrical dryer. It supplies heat to the charged coal to dry it.

400 t / h of blended coal was charged into the dryer, and the steam supply amount (steam temperature 110 ° C.) was adjusted according to the moisture value on the dryer outlet side. When the value decreased to 6.2%, the amount of steam supplied to the dryer decreased to the lower limit of 15 t / h, and the coal moisture value on the outlet side of the dryer decreased to 5%. Therefore, water was added to the coal on the belt conveyor on the dryer inlet side by sprinkling water when the moisture value on the dryer outlet side fell to 6.0% or less. The amount added is 0.8 t / h when the moisture value on the outlet side of the dryer is 6.0%.
In the following, the amount of water was adjusted by proportional control, and control was performed to stop watering when the moisture value on the outlet side of the dryer was 6.2%.
As a result, at the time of water sprinkling, the amount of water sprinkled was about 0.8 to 1.2 t / d, and the moisture value on the outlet side of the dryer could be secured at 6.0% or more.

(Example 2) When operating the dryer with the same equipment as in Example 1, it was found that when the moisture value of the blended coal is below 8%, the coal moisture value on the outlet side of the dryer is below 6%. Was obtained. Therefore, when the coal of various brands is charged into the blending tank with the equipment shown in FIG. 2, the moisture value is measured on the coal transporting conveyor to the blending tank for each brand, and the moisture content is measured based on the value. Water was sprinkled on the upstream side of the conveyor. Specifically, when the measured value of the moisture meter falls below 8.0%, watering is started at a minimum watering amount of 1.5 t / h, watering is performed by proportional control, and the measured value of the moisture meter is 8. Watering was stopped when it reached 2% or more.

By this control, the sprinkling amount at the time of sprinkling is 1.5
The water content of the coal stocked in each blending tank was 8% or more. Then, as a result of using these dryers by blending these coals at a predetermined blending ratio, the coal moisture value on the outlet side of the dryer could be maintained at 6% or more.

(Example 3) When the coke oven was operated by mixing three kinds of coal types A, B and C, the dryer was operated with the same equipment as in Example 1. At the time of loading each coal into the blending tank, coal A has a moisture value of 6 to 8%, and coal B has a moisture value of 7 to 10%.
%, Coal C had a water content value of 10 to 12%.

The blending ratio of coal types A, B and C is 50:30:
As a ratio of 20, when the coke oven was charged using a dryer, the moisture value on the outlet side of the dryer was sometimes lower than 6%. Therefore, using the equipment shown in FIG. Watering was performed when coal A was charged. That is, when the moisture value on the outlet side of the dryer is lower than 6.0% and the coal charged into the blending tank is coal type A, water is sprinkled on the transport conveyor at 2.0 t / h. It was There is a time lag of about 5 hours before the sprinkled coal is cut out from the blending tank and loaded into the dryer, so this control takes 8 hours until the moisture content of the coal on the dryer outlet side stabilizes to 6% or more. Has passed. However, this control does not add extra water to the high-moisture coal, so the amount of steam used can be reduced by about 5 t / d compared to Example 2, and the amount of heat used can be reduced.

[0030]

According to the practice of the present invention, the conventional coke oven charging water content control technology using a dryer cannot control the coal water content in the stockyard, and even when the coal water content decreases, the coal content at the time of charging the coke oven is reduced. The amount of water can be held appropriately, and the amount of fine powder generated during coal carbonization can be reduced. This makes it possible to improve the quality of tar produced as a by-product from the coke oven gas, reduce the adhesion of fine powder on the coke oven furnace wall, and reduce the work of removing carbon adhering to the inside of the furnace. Moreover, the trouble at the time of coke extrusion could be reduced.

[Brief description of drawings]

FIG. 1 is a flow sheet of an example.

FIG. 2 is a flow sheet of an embodiment of the second invention.

FIG. 3 is a flow sheet of an embodiment of the third invention.

FIG. 4 is an overall flow sheet showing a process of charging coal from a yard into a coke oven.

[Explanation of symbols]

11 stockyards 12 reclaimer 13, 16, 18, 21 Transport conveyor 14, 19, 31 Moisture meter 15 mixing tank 17 crusher 20 Dryer (conditioning coal equipment) 23 coal car 24 coke ovens 25 flue 26 Furnace wall carbon 27 Coke oven gas 28 Tar Decanter 29 tar 32, 41, 61 control device 33 Steam source 34 Control valve 42, 52 Water source 43, 53 Regulator valve 44 Watering spray 54 Sprinkler

Claims (3)

[Claims] 1. A method for adjusting the water content of coal charged into a coke oven by using a dryer, wherein the content of the coal on the dryer input side is adjusted so that the water content in the coal on the dryer output side becomes a predetermined value. A method for adjusting the water content of coal for charging into a coke oven, which comprises adding water to the coal. 2. A method for adjusting the water content of a coal charged into a coke oven by using a drier so that the water content in the coal of a single brand of coal charged into a blending tank becomes a predetermined value. To
A method for adjusting the water content of coal for charging into a coke oven, which comprises adding water to the coal on the side of the mixing tank. 3. A method for adjusting the water content of a coal charged into a coke oven by using a dryer, which is charged into a blending tank so that the water content in the coal on the outlet side of the dryer becomes a predetermined value. A method for adjusting the water content of a coal for charging a coke oven, which comprises adding water to a single brand of coal.