JP6135856B2 - Fluidized bed dryer - Google Patents

Description

  The present invention relates to a fluidized bed drying apparatus for drying low-grade coal.

In recent years, in order to efficiently use so-called low-grade coals such as lignite and subbituminous coal with a large amount of reserves but a large amount of water and a low calorific value, they are dried (dehydrated) by drying with a fluidized bed dryer Power generation facilities that use low-grade coal have been developed.
The fluidized bed drying apparatus dehydrates by putting low-grade coal into the fluidized bed container, supplying steam from the lower part of the fluidized bed container, and heating with a heat transfer tube disposed in the fluidized bed container. Yes.

In the fluidized bed drying apparatus configured as described above, it is important to appropriately control the residence time of the low-grade coal in order to appropriately dry the low-grade coal. For example, the fluidized-bed drying device partitions the fluidized bed container with a partition plate or the like. This ensures the residence time of the fluidized bed.
Then, in the fluidized bed container partitioned by the partition plate, the fluidized bed container is partitioned into a plurality of drying chambers by a plurality of partition plates in order to suppress poor movement of raw coal made of low-grade coal. A fluidized bed drying apparatus has been developed that adjusts the opening area of a passage opening of a plate and controls the amount of raw coal passing through the passage opening (see Patent Document 1).

JP 2013-108699 A

  In patent document 1, the passage failure of raw coal is prevented by determining the passage failure of raw coal based on the pressure or temperature deviation near the passage opening part of a partition plate, and adjusting the passage amount of raw coal. Thus, in patent document 1, the flow of the fluidized bed for every drying chamber is controlled by opening and closing of the passage opening part of each partition plate.

  Here, low-grade coal also has a feature of being easily ignited, and there is a risk of ignition if it is excessively dried and heated in a fluidized bed dryer. For example, when the moisture content of low-grade coal is small, there is a problem that the risk of spontaneous ignition increases if the residence time of the fluidized bed becomes long. On the other hand, when the amount of moisture is large, if the residence time of the fluidized bed is short, drying becomes insufficient, and there is a problem that the amount of heat generated per weight cannot be secured.

When a plurality of drying chambers are formed in a fluidized bed container as in Patent Document 1, the amount and flow of the fluidized bed are different for each drying chamber, and there is a problem that the control of the residence time of the fluidized bed is complicated.
The present invention has been made to solve such a problem, and the purpose of the present invention is to easily and appropriately adjust the residence time of the fluidized bed, and stably without fear of spontaneous ignition or the like. The object is to provide a fluidized bed drying apparatus capable of drying low-grade coal.

In order to achieve the above-described object, the fluidized bed drying apparatus according to the present invention is a fluidized bed drying apparatus that dries low-grade coal, and includes a fluidized-bed container that stores the fluidized bed of the low-grade coal, and the low-grade coal. A raw gas that is formed on one side of the fluidized bed container and supplies the low-grade coal into the fluidized bed container, and supplies a fluidized gas for fluidizing the quality coal into the fluidized bed. A charging unit; a dry coal discharging unit that discharges the dried low-grade coal that is formed below the raw coal charging unit on the other side of the fluidized bed container and is dried; A discharge amount adjusting means for adjusting a discharge amount of the dried low-grade coal from a section, a moisture amount detection means for detecting a moisture amount of the low-grade coal supplied from the raw coal input section, and the moisture amount detection According to the moisture content of the low-grade coal detected by the means Controls adjustment means comprises a layer height control means for adjusting the bed height of the fluidized bed of the fluidized bed vessel, and the layer height detecting means for detecting a bed height of the fluidized layer, wherein the layer height control means Is configured to control the discharge amount adjusting means so that the bed height of the fluidized bed detected by the bed height detecting means reaches a bed height set in advance according to the moisture content of the low-grade coal. It is said.

As this, by the bed height set according to the water content of the pre-low-grade coal a bed height of the fluidized bed, it is possible to always ensure optimum residence time.

  Further, the bed height control means reduces the amount of low-grade coal discharged by the discharge amount adjusting means as the water amount of the low-grade coal detected by the moisture amount detection means increases. It is preferable that the discharge amount of the low-grade coal is increased by the discharge amount adjusting means as the moisture amount is small. In this way, the higher the moisture content of the low-grade coal, the higher the bed height can be increased by reducing the discharge of the low-grade coal, and the residence time can be lengthened. By increasing the discharge amount, the bed height is lowered and the residence time can be shortened.

According to the fluidized bed drying apparatus of the present invention using the above means, it is provided with a discharge amount adjusting means for adjusting the discharge amount of the dried low-grade coal, and the discharge amount adjusting means is controlled according to the moisture content of the low-grade coal. Then, the bed height of the fluidized bed is adjusted.
Thus, the residence time of a fluidized bed can be easily and appropriately controlled by adjusting the bed height of the fluidized bed according to the moisture content of the low-grade coal. Thereby, the low-grade coal can be stably dried without fear of spontaneous ignition or the like.

It is a schematic structure sectional view of a fluidized bed drying device concerning one embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view of a fluidized bed drying apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the fluidized bed drying apparatus 1 dries low-grade coal as fuel in, for example, a pulverized coal fired boiler and supplies it to the boiler.

  The fluidized bed drying apparatus 1 includes a fluidized bed container 2 having a hollow rectangular parallelepiped shape, and a fluidized bed S of raw coal made of low-grade coal such as lignite and subbituminous coal is stored in the fluidized bed container 2. Then, the free board portion F is formed above the fluidized bed S. The fluidized bed S has a longitudinal direction as a flow direction, and flows from right to left in FIG.

  A heat transfer tube 3 for heating the fluidized bed S is disposed in the fluidized bed container 2. The heat transfer tube 3 includes a plurality of pipes extending in the width direction in the fluidized bed container 2, and heats the fluidized bed S by passing a high-temperature heat medium such as superheated steam inside. Moreover, the partition plates 4 and 4 extended in the width direction and the height direction are provided in the fluidized bed container 2 at two places. Each of the partition plates 4 and 4 is disposed at a position where it is divided into approximately three equal parts in the flow direction of the fluidized bed container 2 and spaced from the bottom 2a and the ceiling 2b of the fluidized bed container 2.

  Between the bottom 2a of the fluidized bed container 2 and each partition plate 4, there is provided a bottom plate 5 in which a plurality of steam introduction holes 5a (fluidized gas supply portions) are formed, which are supplied from a steam supply source (not shown). The steam (fluidized gas) passes between the bottom 2a and the bottom plate 5 and is jetted into the fluidized bed container 2 from the steam introduction hole 5a. On the other hand, an exhaust pipe 6 for discharging a gas such as steam or gas in the fluidized bed container 2 is connected to the ceiling 2 b of the fluidized bed container 2.

  The fluidized bed container 2 has one end of a raw coal charging pipe 7 (raw coal charging portion) connected to an upper portion of an upstream wall 2c that is an upstream (one side) wall in the flow direction. The other end of the raw coal charging pipe 7 is connected to a coal supplying device 8, and raw coal supplied from the coal supplying device 8 is input into the fluidized bed container 2 through the raw coal charging pipe 7. .

  On the other hand, in the fluidized bed container 2, one end of a dry coal discharge pipe 9 (dry coal discharge portion) is connected to a downstream wall 2d that is a downstream wall (other side) in the flow direction. The dry charcoal discharge pipe 9 is wide open in the height direction at the central portion of the downstream wall 2d, the discharge opening upper end 9a is lower than the input opening lower end 7a of the raw coal input pipe 7, and the discharge opening lower end 9b is It is in a position higher than the lower ends of the partition plates 4 and 4. Further, the dry coal discharge pipe 9 has a tapered shape in which the passage area is reduced toward the downstream side. The dry coal discharge pipe 9 is provided with a rotary valve 10 (discharge amount adjusting means), and the discharge amount of dry coal can be adjusted according to the number of rotations of the rotary valve 10.

The raw coal charging pipe 7 is provided with an infrared moisture sensor 11 (moisture amount detection means) for detecting the moisture content of the raw coal to be input. Further, a bed height sensor 12 (bed height detection means) for detecting the bed height of the fluid bed S is provided on the upstream wall 2c of the fluid bed container 2.
The rotary valve 10, the moisture sensor 11, and the bed height sensor 12 are electrically connected to a control device 13 (bed height control means).

  The control device 13 receives the moisture content information of the raw coal detected by the moisture sensor 11 and the bed height information detected by the bed height sensor 12, and the control device 13 controls the rotary valve 10 based on these information. Control. Specifically, the bed height set according to the moisture content of the raw coal is stored in advance in the storage unit of the control device 13, and the control device 13 responds to the moisture content information acquired by the moisture content sensor 11. The rotational speed of the rotary valve 10 is adjusted so that the layer height stored in the storage unit is obtained. Here, the bed height set according to the moisture content of the raw coal is, for example, a bed height for ensuring a residence time that can sufficiently dry low-grade coal while preventing spontaneous ignition, The larger the amount, the higher the layer height so that the residence time becomes longer.

Hereinafter, the operation of the fluidized bed drying apparatus 1 configured as described above will be described.
First, raw coal is introduced into the fluidized bed container 2 from the coal feeder 8 through the raw coal introduction pipe 7. And, by supplying steam from the steam introduction hole 5a of the bottom plate 5 to the raw coal in the fluidized bed container 2, a fluidized bed S is formed, and the fluidized bed S is heated by the heat transfer tube 3 to promote drying. It is.

  The movement of the fluidized bed S is blocked by the partition plates 4 and 4, and moves downstream through the partition plates 4 and 4. The gas supplied from the steam introduction hole 5a and the gas generated by drying the raw coal are discharged to the exhaust pipe 6 through the free board portion F. Then, the dry coal from which the raw coal is dried passes through the dry coal discharge pipe 9 and is discharged in an amount corresponding to the rotational speed of the rotary valve 10. The dry coal discharged from the fluidized bed drying apparatus 1 is supplied to the boiler via a pulverized coal machine (mill) not shown. The dry coal does not necessarily have to be supplied to the boiler via a pulverized coal machine (mill) or the like, and may be supplied directly from the dry coal discharge pipe 9 to the boiler.

While the low-grade coal is dried in this way, the control device 13 monitors the moisture content of the raw coal with the moisture sensor 11 and controls the number of rotations of the rotary valve 10 according to the increase or decrease of the moisture content. The bed height of the fluidized bed S is adjusted.
For example, when the bed height h1 of the fluidized bed S indicated by the solid line in FIG. 1 is described as the reference time, the control device 13 determines that the water content detected by the water content sensor 11 is greater than the water content at the reference time. In order to increase the bed height, the rotational speed of the rotary valve 10 is lowered to reduce the amount of dry coal discharged. If the input amount of raw coal is constant, the amount of raw coal in the fluidized bed container 2 is increased by reducing the amount of dry coal discharged, and the bed height of the fluidized bed S is higher than the bed height h1 at the reference time. . And the control apparatus 13 controls the rotary valve 10 to the rotation speed which maintains the bed height which achieves the bed height according to the moisture content of the raw coal by which the bed height detected by the bed height sensor 12 is preset. To do. Thereby, about the fluidized bed S which consists of raw coal with much moisture content, residence time can be lengthened and sufficient drying time can be ensured.

  On the other hand, when the moisture amount detected by the moisture amount sensor 11 is lower than the moisture amount at the reference time, the control device 13 increases the rotational speed of the rotary valve 10 to reduce the bed height and reduces the dry coal. Increase emissions. If the input amount of raw coal is constant, the amount of raw coal in the fluidized bed container 2 decreases as the dry coal discharge increases, and the bed height of the fluidized bed S becomes lower than the bed height h1 at the reference time. And the control apparatus 13 will control the rotary valve 10 to the rotation speed which maintains a bed height, if the bed height detected by the bed height sensor 12 achieves the bed height according to the moisture content of raw coal. Thereby, about the fluidized bed S which consists of raw coal with little moisture content, residence time can be shortened, it can suppress that it dries excessively, and can prevent spontaneous ignition.

  In the fluidized bed container 2 in the present embodiment, the discharge opening lower end 9b of the dry coal discharge pipe 9 is lower than the input opening lower end 7a of the raw coal input pipe 7, and is higher than the lower ends of the partition plates 4 and 4. Thus, as shown by a chain line at the bottom of the fluidized bed container 2 in FIG. 1, the fluidized bed S can be lowered to a bed height h2 corresponding to the height position of the discharge opening lower end 9b. On the other hand, the lower end 7a of the input opening 7 of the raw coal input pipe 7 is higher than the lower end 9b of the discharge opening 9 of the dry coal discharge pipe 9 above the upstream wall 2c. As can be seen, the fluidized bed S can be raised to a bed height h3 corresponding to the height position of the lower end 7a of the charging opening. Thus, by forming the position of at least the discharge opening lower end 9b of the dry coal discharge pipe 9 in the lower portion of the downstream wall 2d below the input opening lower end 7a of the raw coal input pipe 7, the bed height can be adjusted in a wide range. can do.

  As described above, the fluidized bed drying apparatus 1 in the present embodiment includes the rotary valve 10 that adjusts the discharge amount of the dried low-grade coal, and the control device 13 controls the rotary valve 10 according to the moisture content of the raw coal. Thus, the bed height of the fluidized bed S is adjusted. In this way, by setting the bed height of the fluidized bed S to the bed height set in advance according to the moisture content of the low-grade coal, it is possible to always ensure the optimum residence time.

From these things, the fluidized bed drying apparatus 1 can control the residence time of the fluidized bed S easily and appropriately, and can dry low-grade coal stably without fear of spontaneous ignition or the like.
This is the end of the description of the present embodiment, but the embodiment of the present invention is not limited to this.
In the above embodiment, the dry coal discharge pipe 9 is provided in the central portion of the downstream wall 2d of the fluidized bed container 2, but the mounting position of the dry coal discharge pipe is not limited to this. For example, the lower end of the discharge opening of the dry coal discharge pipe on the downstream wall of the fluidized bed container is further lowered to the position near the bottom plate of the fluidized bed container, or the opening of the dry coal discharge pipe is formed on the bottom plate of the fluidized bed container. Or you may. As the opening of the dry coal discharge pipe is formed at a lower position of the fluidized bed container as described above, the bed height of the fluidized bed can be lowered, and the adjustment range of the bed height can be increased.

  Moreover, although the fluidized-bed drying apparatus 1 in the said embodiment supplies the low grade coal dried as fuel pre-processing of a pulverized coal burning boiler, this invention can also be applied to another fluidized-bed drying apparatus. it can. For example, a fluidizing medium such as sand is introduced into a fluidized bed container together with low-grade coal, steam (or fluidized gas) is introduced into the fluidized bed from the steam introduction hole of the bottom plate, and the fluidized bed is heated with a heat transfer tube. You may apply to the two-column type | mold gasification furnace tower | column which sends the low-grade coal after gasification to a combustion furnace with sand, gasifying raw coal by making it dry.

DESCRIPTION OF SYMBOLS 1 Fluidized bed drying apparatus 2 Fluidized bed container 2c Upstream wall 2d Downstream wall 3 Heat exchanger tube 4 Partition plate 5 Bottom plate 5a Steam introduction hole (fluidization gas supply part)
7 Raw coal input pipe (raw coal input section)
7a Input opening bottom 9 Dry coal discharge pipe (dry coal discharge part)
9a Discharge opening upper end 9b Discharge opening lower end 10 Rotary valve 11 Moisture content sensor (moisture content detection means)
12 layer height sensor (layer height detection means)
13 Control device (layer height control means)

Claims (2)

A fluidized bed drying device for drying low-grade coal,
A fluidized bed container for storing a fluidized bed of the low-grade coal;
A fluidized gas supply unit for supplying a fluidized gas for fluidizing the low-grade coal into the fluidized bed;
A raw coal input unit that is formed on one side of the fluidized bed container and supplies the low-grade coal into the fluidized bed container,
A dry coal discharge unit that is formed below the raw coal input unit on the other side of the fluidized bed container and discharges the dried low-grade coal from the fluidized bed container;
A discharge amount adjusting means for adjusting a discharge amount of the dry low-grade coal from the dry coal discharge unit,
Moisture content detection means for detecting the moisture content of the low-grade coal supplied from the raw coal input unit;
According to the moisture content of the low-grade coal detected by the moisture content detecting means, controlling the discharge amount adjusting means, and adjusting the bed height of the fluidized bed in the fluidized bed container;
A bed height detecting means for detecting a bed height of the fluidized bed;
Equipped with a,
The bed height control means includes the discharge amount adjusting means so that the bed height of the fluidized bed detected by the bed height detection means reaches a bed height set in advance according to the moisture content of the low-grade coal. A fluidized bed drying apparatus characterized by controlling . The bed height control means reduces the discharge amount of the low-grade coal by the discharge amount adjustment means as the water amount of the low-grade coal detected by the moisture amount detection means increases. fluidized bed dryer according to claim 1, wherein increasing the emissions of the low-grade coal by little as the discharge amount adjusting means.

Images