JPS58127782A - Rotary drier for fine coal for coke equipped with indirect heating tubes - Google Patents

Abstract

PURPOSE:To dry five coal for coke econimically, by flowing hot air into a rotary cylinder from outside at the feed end to effect aeration and predrying of fed coal quickly. CONSTITUTION:Heat medium oil H is fed, via an inlet tube 6 of a rotary joint 5, into numerous heating tubes 4 arranged at intervals in the radial directions near the periphery in parallel to the axis in a horizontal rotary cylinder 1, and the oil is heated. Raw material five coal for coke oven C is fed into the rotary cylinder 1 through a feed opening 2 and pressurized hot air W is sent into an annular aeration shell 81 of an air supply device 8 installed on the outer circumference of the feed end of the rotary cylinder 1, via air supply chambers 85 partitioned by the shell 81 and partitioning plates 84 and a dispersion plate 83. Thus five coal is fluidized and predried, brougth in contact with the heating tubes 4 for drying and is discharged from the cylinder through outlet 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises an indirect heating section in which a large number of heating tubes are built in a rotary cylinder in parallel with its axis, and an aeration drying section provided on the supply side of the product to be dried. The present invention relates to an indirect heating tube rotary drying device for coke oven raw pulverized coal.

A rotary dryer with an indirect heating tube (usually called a steam blow dryer) has a large heating area per volume, a large drying capacity, a fast heat transfer rate, and does not require exhaust gas treatment equipment. It has the advantage of being versatile and easy to operate.

However, when using this dryer to pre-dry pulverized coal to be charged into a coke oven to save energy in the coke oven, there are the following major problems. That is,
First, if the moisture content of powdered coal is 10% or more on a wet basis,
Water adhering to the powdered raw coal itself causes adhesion on the inner surface of the rotating cylinder, which is the non-heating surface of the dryer, and the powdered coal particles themselves aggregate with moisture as inclusions, causing heating especially at the dryer entrance. Powdered coal adheres to the pipe surface and prevents replacement with new powdered coal that is successively supplied.The t1 contact degree and contact area decrease, leading to a significant decrease in the thermal efficiency (overall heat transfer coefficient) of the dryer, and the expected In order to process the throughput, it is necessary to prepare a dryer larger than the dimensions obtained from the original heat transfer calculation.

Second, the high-moisture coking coal for coke ovens has high frictional resistance, so it has poor fluidity and accumulates in a high mountain at the entrance of the dryer as shown by the imaginary line C' in Figure 1, making it difficult to exit from the smooth entrance. As a result, the desired drying ability could not be obtained, resulting in f'1. Furthermore, this resulted in an unnecessarily increased heat transfer area and increased equipment size.

Third, the deposits on the heating tube and rotating cylinder may peel off during operation and become lumps, which may impede the effect of contact with the heating surface, or
It may also cause clogging of dried products.

The inventors of the present invention strongly focused on this point, and found that in order to reliably solve the above problems while retaining the advantages of this type of dryer, hot air is blown from the surroundings into the interior on the supply side of the rotating cylinder. We discovered that it is a good idea to rapidly ventilate and pre-dry the pulverized coal supplied prior to main drying in that area, and eliminate the high moisture condition that tends to cause the troubles mentioned above. The invention was completed.

The present invention will be explained below using specific examples shown in the drawings.
Reference numeral 1 denotes a rotating cylinder, which is rotatable around its axis by means of (2) a rotating drive means (not shown).

In addition, this rack is installed horizontally with an inverted downward slope when viewed from the supply side. The product to be dried, for example, the above-mentioned raw material pulverized coal C for a coke oven, is supplied from the supply port 2 provided at one end of the rotating cylinder 1, and is subjected to a drying operation inside the rotating cylinder 1, and a dried product is formed at the other end. It is discharged from the discharge port 3. Also, the rotary cylinder 1
Inside, there are a number of heating tubes 4 running parallel to the axis along its entire length.
, 4, . As shown in FIG. 3, the heating tubes 4 are provided at intervals in the circumferential direction and also at intervals in the radial direction.

A heat medium oil H as a heat medium is supplied to these heating pipes 4 via a heat medium oil inlet pipe 6 of a rotary joint 5. After being collected in the header, it is returned to the rotary joint 5 and exits from the n1 heat transfer oil outlet pipe 7.

(3) Although such a configuration is basically known, in the present invention, an aeration drying section 8 is provided on the pulverized coal supply side. That is, an annular ventilation shell 81 is provided on the outer periphery of the supply side portion of the rotary cylinder 1, and a ventilation dispersion plate 83 is provided inside the annular ventilation shell 81.
are arranged in a ring. This dispersion plate 83 is made of a porous material (for example, sintered metal) having fine holes that allow hot air to pass through but prevent the powdered coal C from falling. In addition, as shown in FIG. 2, the hot air W forced into the ventilation shell 81 is
In order to feed only the bed of powdered coal C, the ventilation shell 81
The annular passage, which is the gap between the pulverized coal C and the dispersion plate 83, is divided into several air blowing chambers 85 that are partitioned in the circumferential direction by a partition plate 84. During air feeding, hot air is evenly blown into the bed of powdered coal C. A damper 82 for adjusting the air volume is installed at the entrance of the air supply chamber 85 so that the supply port 2
When pulverized coal C is charged into the rotary cylinder 1, it receives heat from the heat transfer oil H passing through the heating tube 4 and dries (4).Then, the rotary cylinder 1 rotates and is arranged so that it is slanted so that the pulverized coal C is sequentially removed from the outlet. Transferred to the side. Further, hot air is passed through the bed of powdered coal C at the supply side portion of the rotary cylinder 1. the result,
As the bed becomes fluidized, the freshly supplied pulverized coal C undergoes preliminary drying. Thus powdered coal C
Combined with the decrease in the moisture content of the coal and the fluidization of the bed, the powdered coal C
This reduces the adhesion of the particles and prevents them from stagnation on the supply side as shown in FIG. 1C'.

Normally, in this ventilation drying, the receiver has 10 to 20 parts of the total dry amount, and the remaining 90 to 80 parts is carried by the drying operation section using an indirect heating tube. The drying capacity of crow is much greater when using an indirect heating tube.

However, in view of the fact that the above-mentioned problem will occur if everything is done by F, by pre-drying and fluidizing the pulverized coal C on the supply side, it is possible to prevent the high moisture pulverized coal C from adhering to heating pipes, etc. This skillfully eliminates the stagnation on the supply side. As a result, compared to the conventional method of increasing the size of the device, increasing the heat transfer area, and increasing the slope and rotation speed of the rotating tube,
It is extremely economical since it is not necessary at all.

By the way, in the above example, the heating tube is provided over almost the entire length, but if necessary, the heating tube can be omitted in the ventilation drying part.

Although it depends on the dimensions of the equipment, the moisture content of the powdered coal, and the processing amount, the hot air temperature is usually 500 to 250℃, and the hot air volume is 0.5 to 0.
．． 15 It is desirable to use N7717 and 9 powdered coal.

As described above, the present invention has excellent effects in terms of economy and prevention of operational troubles, and is particularly effective in drying coking powder coal for coke ovens.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of a rotary drying device according to the present invention, and Fig. 2 is a schematic cross-sectional view taken along the line ■-■. Part 81... Ventilation shell 83... Dispersion plate C... Powdered coal H... Heat transfer oil W... Hot air patent applicant Nippon Steel Corporation Tsukishima Kikai Co., Ltd. 543

Claims (1)

[Claims] (1) The product to be dried is supplied from one end of the horizontal rotary cylinder and the product is discharged from the other end, and the supply side of the product to be dried is equipped with an aeration drying section that blows hot air into the interior from the surroundings. 1. A rotary dryer with an indirect heating tube for coke oven raw powder coal, characterized in that an indirect heating tube is provided in the rotating cylinder over substantially the entire length of the rotating cylinder or from the ventilation drying section to the other end.