JPH0230356B2 - KANSETSUKANETSUKANTSUKIKAITENKANSOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes 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 at a supply side portion of the product to be dried. The present invention relates to an indirect heating tube rotary drying device particularly suitable for drying coke oven raw material pulverized coal.

Rotary dryers with indirect heating tubes (usually called steam tube dryers) have a large heating area per volume, large drying capacity, high heat transfer rate, no need for exhaust gas treatment equipment, and easy operation. It has the advantage of being easy to use and is widely used.

However, when this dryer is used to pre-dry pulverized coal to be charged into a coke oven in order to save energy in the coke oven, there are the following major problems. Firstly, when the moisture content of powdered coal is 10% or more on a wet basis, adhesion occurs on the inner surface of the rotating cylinder, which is the non-heated surface of the dryer, due to the wet wall effect of the adhering water of raw material powdered coal itself, and powdered coal particles The pulverized coal itself aggregates with moisture as inclusions, and pulverized coal adheres to the surface of the heating tube, especially at the inlet of the dryer, inhibiting replacement with new pulverized coal that is successively supplied, reducing the contact frequency and contact area, and causing damage to the dryer. This results in a significant decrease in thermal efficiency (overall heat transfer coefficient), and in order to handle the desired amount of processing, a dryer larger than the dimensions obtained from the original heat transfer calculations must be prepared. .

Second, the high-moisture coking coal for coke ovens has high frictional resistance, so it has poor fluidity and stays at a high level at the entrance of the dryer, as shown by the imaginary line C' in Figure 1, and flows smoothly from the entrance to the exit. Direct movement was obstructed, and the desired drying capacity could not be obtained, resulting in an unnecessarily increased heat transfer area and larger equipment.

Thirdly, deposits on the heating tube or rotary cylinder may peel off during operation and become lumps, which may impede the effect of contact with the heating surface or cause clogging of the dried product.

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, it was necessary to The inventors have discovered that it is sufficient to quickly aerate and pre-dry the supplied powdered coal prior to main drying in that area, thereby alleviating the high moisture condition that tends to cause the above-mentioned troubles, and have developed the present invention. I was able to complete it.

The present invention will be described below with reference to a specific example shown in the drawings. Reference numeral 1 denotes a rotary cylinder, which is rotatable around an axis by a rotation drive means (not shown). Also, this is installed horizontally with a 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 rotary cylinder 1, undergoes a drying operation in the rotary cylinder 1, and the dried product is passed through the exhaust gas formed at the other end. It is discharged from outlet 3. In addition, a large number of heating tubes 4, 4, etc. are disposed within the rotating tube 1 over its entire length in parallel with the axis, and are supported by tube plates at both ends and a support plate (not shown) in the middle. It is integrated with tube 1. As shown in FIG. 2, 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, passed from the right side to the left side in FIG. After being collected, it is returned to the rotary joint 5 and exits from the heat transfer oil outlet pipe 7.

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, openings 1a, 1a, . . . are formed at intervals in the circumferential direction on the supply side portion of the rotary cylinder 1, and an air permeable dispersion plate 83 is annularly disposed in these openings. This dispersion plate 83
is made of porous material (for example, sintered metal) with fine holes that allow hot air to pass through but prevent powdered coal C from falling. Furthermore, an annular ventilation shell 81 is provided around the opening 1a and the dispersion plate 83, and the hot air W forced into the ventilation shell 81 is directed only to the bed of powdered coal C, as shown in FIG. In order to supply air, the annular passage that is the gap between the ventilation shell 81 and the rotary cylinder 1 is divided into several air supply chambers 85 that are partitioned in the circumferential direction by partition plates 84. A damper 82 for adjusting air volume is installed at the entrance of the air blowing chamber 85 so that hot air is evenly blown into the bed.

In the rotary drying device configured in this way,
When pulverized coal C is charged into the rotary cylinder 1 from the supply port 2, it receives heat from the heat transfer oil H passing through the heating tube 4 and dries, and is sequentially sent to the outlet side by the rotation and tilting arrangement of the rotary cylinder 1. be transported. In addition, a dispersion plate 38 is attached to the bed of powdered coal C at the supply side portion of the rotating cylinder 1.
Hot air is passed through. As a result, the bed is fluidized and the powdered coal C that has just been supplied is pre-dryed. In this way, the decrease in moisture content of pulverized coal C and the fluidization of its bed result in a decrease in the adhesion of pulverized coal C, as shown in Figure 1.
Retention at supply side sites such as C' is prevented.

Normally, this ventilation drying is responsible for 10 to 20% of the total dry amount, and the remaining 90 to 80% is handled by the drying operation section using indirect heating pipes. In terms of drying capacity, indirect heating pipes are much larger. However, considering that the above-mentioned problem will occur if everything is done according to this, 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 effectively eliminates the stagnation. As a result, compared to the conventional methods of increasing the size of the equipment, increasing the heat transfer area, and even increasing the slope and rotation speed of the rotating tube, there is no need to do so. Therefore, it is extremely economical.

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 section.

Although it depends on the dimensions of the equipment, moisture content of powdered coal, processing amount, etc., the hot air temperature is usually 500 to 250℃, and the hot air volume is
It is desirable to use 0.05 to 0.15Nm ³ /Kg of powdered coal.

As described above, the present invention brings about excellent effects in terms of economy and prevention of operational troubles, and is particularly effective in drying raw material pulverized coal for coke ovens.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a rotary drying apparatus according to the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line arrow.
FIG. 3 is a front view of the main part of FIG. 1. 1... Rotating tube, 4... Heating tube, 8... Ventilation drying section, 81... Ventilation shell, 83... Distribution plate, C...
...Powdered coal, H...Heating medium oil, W...Hot air.

Claims (1)

[Claims] 1 The product to be dried is supplied from one end of the horizontal rotating cylinder and the dried product is discharged from the other end, and there is sufficient space on the supply side of the dried product from around the rotating cylinder to the inside to fluidize the product to be dried. A ventilation drying section that blows hot air is installed,
A rotary drying device with an indirect heating tube, 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.