JPH10300344A - Manufacturing device of coal ash hardened grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of an adhering substance due to the powder contained in exhaust air which comes from a dryer, when hardened grains are manufactured from coal ashes. SOLUTION: A bypass duct 2' is provided between a hot-air duct 2, which guides hot air to a dryer drum 1 for drying granulated and hardened coal ashes, and an exhaust air duct 9' from the dryer drum 1, so that the part of the hot-air is guided to the exhaust air duct 9'. Thereby, the exhaust air temperature of the diameter of a hot-air inlet point is made to be 80 to 110 deg.C. Moreover, the exhaust air duct 9' has the length in which the residence time of the powder in the same duct is 1 second or longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing hardened coal ash granules suitable for use as a fluidization preventive added to asphalt pavement.

[0002]

2. Description of the Related Art FIG. 2 is a conceptual view of a conventional apparatus for producing hardened coal ash particles. After mixing a hardening material such as cement with coal ash, granulating, curing and hardening, and drying it to produce hardened coal ash granules, a drum rotating hot air dryer that is inexpensive and easy to operate is generally used for drying. Used for

[0003] In FIG. 2, hardened particles before drying are introduced into a dryer receiving chute 7 by a conveyor 6, and are dried and discharged by hot air sucked from a hot air duct 2 while moving in a dryer drum 1. Lower hood 4 of side hood 3
And in the downstream process is processed as a product of hardened particles, for example, sieved.

On the other hand, the hot air is cooled by drying the hardened particles in the dryer drum 1 and becomes exhausted air containing powder accompanying the hardened particles and powder generated by powdering of the hardened particles. The air is sucked and discharged to the atmosphere via the exhaust duct 9 and the dust collector 10.

[0005] In this process, the amount of powder collected by the dust collector 10 is so large that it is practically difficult to dispose of it. Therefore, the powder is transported as a so-called return material to the raw material hopper for granulation.

The dust collected by the dust collector 10 may be transported as it is, but the coarseness of the collected powder impairs the granulation properties. Therefore, in many cases, the dust collected by the dust collector 13 is vacuum-transported by the transport pipe 14 after being pulverized by the pulverizer 13. In the figure, 5 indicates hardened particles, 8 indicates a receiving chute, and 12 indicates a conveyor.

[0007]

In the apparatus shown in FIG. 2, since the water content of the powder collected from the exhaust air of the dryer is high, any type of pulverizer (for example, hammer crusher type, ball mill In such a case, the powder adheres to and grows on the crusher (for example, a hammer) or the inner surface of the casing, and eventually makes the operation of the crusher impossible.

[0008] In particular, in order to keep the product quality of powder generated from hardened particles made of coal ash and cement as a raw material, the temperature of hot air is generally suppressed to 200 ° C or less. Since the wind temperature is reduced to about 50 ° C., the water content of the powder is about 8 to 10%, which is a condition under which the powder (particles) is likely to be fixed by collision with a metal object.

Further, the powder after pulverization is generally transported by vacuum or pneumatically. In this case, there is a case where a sticking matter is generated particularly in a bent portion of the pipe, and the pipe may be blocked.

An object of the present invention is to provide an apparatus for producing hardened coal ash particles, in which a solid matter is prevented from being generated by powder contained in exhaust air from a drying device when hardened particles are manufactured from coal ash. It is an issue.

[0011]

According to the present invention, a coal ash generated from a pulverized coal-fired boiler is used as a raw material, and a hardening agent such as cement is added thereto, granulated, cured and hardened, and then hardened by hot air drying with a hot air dryer. The following means are adopted in order to solve the above-mentioned problems in an apparatus for producing grains.

That is, in the apparatus for producing hardened coal ash particles according to the present invention, a part of the hot air supplied to the drying device is bypassed and introduced into the exhaust duct of the hot air drying device, and the exhaust air temperature immediately after the introduction point is set. Is set to 80 ° to 110 ° C., and the length of the exhaust duct is set to a length such that the residence time of the powder in the duct is 1 second or more.

The apparatus for producing hardened coal ash particles according to the present invention has the above-described configuration, and a part of the hot air supplied to the drying apparatus is introduced into the exhaust duct of the hot-air drying apparatus via a bypass duct. By setting the exhaust air temperature to 80 ° C to 110 ° C and keeping the powder in the exhaust air duct for 1 second or more, the moisture content of the powder accompanying the exhaust air from the hot air drying device is reduced.

This prevents a problem that the powder adheres to a pulverizer or a facility for pneumatic transportation provided in a line for collecting and reusing the powder from the exhaust air of the hot-air drying apparatus and causes blockage. be able to.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an apparatus for producing hardened coal ash particles according to the present invention will be specifically described based on an embodiment shown in FIG. In the following embodiment, FIG.
Are denoted by the same reference numerals for simplicity of description.

In FIG. 1, a bypass duct 2 'is provided between a hot air duct 2 for supplying hot air to the hot air drying device and an exhaust duct 9' of the hot air drying device. The hot air duct 2 and the bypass duct 2 ′ are provided with air volume adjustment dampers 21 and 22, respectively.

A bypass duct 2 ′ having a downstream portion communicated with the exhaust duct 9 ′ receives the suction pressure of the suction fan 11, and an upstream portion has a built-in air volume adjustment damper 22 and is provided with an air volume adjustment damper 21 of the hot air duct 2. Since it communicates with the upstream side, a part of the hot air is separated from the hot air duct 2 and is discharged from the exhaust duct 9 ′.
It is introduced inside.

As a result, the temperature of the exhaust air in the exhaust duct 9 'rises. The degree of the rise in the temperature of the exhaust air is determined by how much the moisture content of the powder contained in the exhaust air is reduced.
0 ° C. is preferred. The adjustment is performed by the air volume adjustment damper 2
Airflow adjustment damper 2 in front of suction fans 11 and 22
3 can be adjusted.

The exhaust duct 9 'is for performing so-called flash drying. In the conventional apparatus, the powder accompanying the exhaust air from the hot-air drying apparatus floats for a short time in the exhaust air duct, which is usually designed to be a minimum and has a shortened conduit, in the exhaust air whose temperature has been reduced in the dryer drum 1. While being transported,
The dust is collected by the dust collector 10.

On the other hand, in the apparatus of the present invention, the volume required to reduce the water content of the powder accompanying the exhaust air is maintained, and the time for which the powder is suspended and retained is increased. The hardened coal ash particles targeted by the present invention may be 1 second or longer.

In this way, it is possible to increase the temperature of the exhaust air from the hot air drying device and reduce the water content of the powder collected from the exhaust air by the dust collector 10.

In order to increase the temperature of the exhaust air, it is possible to increase the amount of hot air introduced into the dryer drum 1 without providing a bypass duct. There is a disadvantage that the amount of powder contained in the wind increases and the capacity of the dust collector 10 and the crusher 13 for processing the exhaust air increases.

In contrast, the provision of the bypass duct 2 'according to the present invention introduces the minimum amount of heat required for drying into the dryer drum 1 and therefore increases the amount of powder contained in the exhaust air. There is an advantage that the exhaust air temperature can be raised without any need.

The effects of the present invention will be described with reference to specific test examples. In the apparatus of FIG. 1, a rotary drum dryer (counter flow, 2 m in diameter × 15 m in length) is used as a hot air drying apparatus.
The hot air temperature was 200 ° C., the hardened particles before drying were coal ash hardened particles having a particle size of 0 to 5 mm, and the dry feed amount was 4 tons / h. The residence time in the exhaust duct 9 'was set to 1 second. Table 1 shows the results of a two-case test without the bypass duct 2 'and with the bypass duct 2'.

[0025]

[Table 1]

As is clear from the results shown in Table 1, when the bypass airflow is 40 Nm ³ / min in the <Test Example 1> with the bypass duct compared to the case without the bypass duct 2 ′,
The exhaust air temperature at the exhaust duct inlet was reduced from 55 ° C to 80 ° C, and as a result, the moisture content of the collected powder was reduced from 9% to 4%. Also, if the bypass air flow rate is 88 Nm ³ / min in <Test Example 2> with a bypass duct, the exhaust air temperature at the exhaust air duct entrance is 10
The temperature was 0 ° C., and the moisture content of the collected powder was further reduced to 2%.

[0027]

As described above, according to the present invention, the hot air drying device is provided with the bypass duct for bypassing a part of the hot air to the exhaust air duct and has a large length of the exhaust air duct. The moisture content of the powder accompanying the exhaust air can be reduced by increasing the wind temperature and increasing the residence time in the exhaust air duct.

As a result, it is possible to prevent the powder from being blocked by a pulverizer, a pneumatic transport device, or the like provided when the powder is collected and reused. Further, according to the present invention, since the amount of hot air supplied to the hot air drying device is not increased, the amount of powder emitted from the hot air drying device can be suppressed to an amount corresponding to the amount of hot air required for drying.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for producing hardened coal ash particles according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional apparatus for producing coal ash hardened particles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dryer drum 2 Hot air duct 2 'Bypass duct 3 Discharge side hood 4 Lower bottom chute 5 Hardened particle 6 Conveyor 7 Receiving chute 8 Receiving chute 9, 9' Dust duct 10 Dust collector 11 Suction fan 12 Conveyor 13 Crusher 14 Transport pipe 21,22,23 Air volume adjustment damper

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Kunihisa Fujiwara, Ryomei Giken Co., Ltd., 1-20-24 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima

Claims (1)

[Claims] 1. An apparatus for producing hardened granules by adding a hardening material such as cement using coal ash generated from a pulverized coal-fired boiler as a raw material, performing granulation, curing and curing, and drying with hot air with a hot air drying device. A bypass duct for bypassing a part of the hot air supplied to the hot-air drying device and introducing the hot-air into the exhaust duct of the hot-air drying device to adjust the exhaust temperature immediately after the introduction point to 80 ° C to 110 ° C is provided. An apparatus for producing hardened coal ash particles, wherein the length of the wind duct is set to a length such that the residence time of the powder in the duct is 1 second or more.