JPS5881A - Method of burning coke of vertical baking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for burning coke in a vertical calciner for calcining limestone, dolomite, magnesite and other similar raw materials.

Conventional vertical calcination equipment used gas or heavy oil to calcinate raw materials such as limestone, but in order to reduce fuel costs and increase the versatility of the fuel, a method of co-firing coke and raw materials has been widely adopted. There is.

However, if such a method of co-firing raw materials and coke is adopted, the following disadvantages arise.

Namely.

(1) When raw rock and coke are mixed and charged at the top of the furnace, if the combustion rate is not controlled, rapid combustion will occur, and only the coke portion will be in an overheated state, resulting in a sintered state and blocks. However, the coke ash melts and solidifies and adheres to the product, causing uneven baking and consuming excess heat.

(2) Coke ash gets mixed into the product and reduces quality.

The present invention has been made in order to eliminate the conventional drawbacks as described above.

Next, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, a firing furnace 1 has a preheating zone 2 at its upper end,
It is divided into a continuous firing zone 3 below it.

A raw material charging device 5 is provided at the top of the outer cylinder 4 of the firing furnace 1 .

Raw materials are supplied to this raw material input device 5 via a belt conveyor 6 and a hopper 7.

Inside near the top of the outer cylinder 4 is a middle cylinder 8 for taking out combustion gas.
are arranged concentrically. A gap 9 for sucking combustion gas and coke ash is formed at the lower end of the middle cylinder 8. Further, the upper end portion of the middle cylinder 8 is continuous with the exhaust pipe 10. This exhaust pipe 10 is connected to a heat exchanger 12 via piping 11. The heat exchanger 12 is guided through a pipe 13 to a dust collector 15 by an exhaust gas fan 14 . After the exhaust gas is dedusted, it is discharged into the outside air.

Combustion air is supplied to the heat exchanger 12 via a pipe 16 by a fan 17, and is heat exchanged with high-temperature exhaust gas in the heat exchanger 12, and is heated in advance to the firing zone 6 of the firing furnace 1. over multiple stages.

It is also supplied as combustion air to a plurality of burners 18 installed at predetermined intervals in the circumferential direction.

Further, a product take-out device 19 is provided at the lower end of the firing furnace 1 .

Based on the above-described structure, in the present invention, in order to avoid rapid combustion of coke, the raw material to be charged is mixed evenly with coke corresponding to the amount of heat of the co-firing ratio, and then the raw material is fed from the raw material charging device 5 at the top of the furnace. The coke is placed in a calcining furnace 1, and as it descends through a preheating zone 2 at the top of the furnace, the temperature is raised to the ignition temperature range of preheated coke by high-temperature combustion gas. Then, by keeping the combustion air ratio low during heavy oil or gas combustion using the burner 18 installed in the firing zone, the amount of oxygen in the combustion gas is reduced, suppressing the combustion speed of coke and preventing local overfiring. do. For example, when the co-firing rate is about 20%, the overall combustion air rate of heavy oil or gas in the burner 18 is about 1.20 to 1.25%.

On the other hand, in order to prevent the ash after coke combustion from getting mixed into the product, the coke is burned as described above, the ash is pulverized, and the middle cylinder 8 is used to remove the ash from the boundary between the preheating zone and the firing zone. The gas is emitted along with the ash. A gap 9 is formed at the lower end of the middle cylinder 8 due to the repose angle of the raw material in order to take out the gas.

In this way, the coke descends through the pre-preparation zone 2.

The ash slowly burns while descending to the firing zone 3, and the ash becomes powder, which is sucked together with the combustion gas from the cavity 9 of the middle cylinder 8, and can be taken out to the outside.

According to experiments of the present invention, by employing the above-described apparatus, about 90% of the coke ash could be extracted to the outside.

Since the combustion gas in the firing zone 6 has a calorific value greater than that required for preheating the raw material in the preheating zone 2, the combustion air of the burner 18 is preheated via the heat exchanger 12, and waste heat is recovered.

FIG. 2 shows the main part of another embodiment of the present invention.

In this embodiment, the diameter of the outer cylinder 4 of the preheating zone 2 is made smaller, and a step is provided between the diameter of the outer tube 4 in the firing zone 6 and the raw material falling in the preheating zone 2 having a small diameter is breathed. A cavity 9 is formed by the corner, and combustion gas is to be discharged from this part. Even if such a configuration is adopted, the same effect as the embodiment shown in FIG. 1 can be obtained.

As is clear from the above explanation, according to the present invention, the combustion rate of coke is suppressed, overheating is prevented, coke ash is pulverized, and combustion gases are transported from the boundary between the preheating zone 2 and the firing zone 3 to the outside. Because the system uses a structure that discharges waste into the air, it does not create blocks like conventional products and does not adhere to or mix with the product.

The quality of baked products can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention. 2. FIG. 1 is a longitudinal cross-sectional view of a main part of another embodiment of FIG. 1. 1 is a firing furnace, 2 is a preheating zone, 3 is a firing zone, 4 is an outer cylinder, 5 is a raw material feeding device, 6 is a belt conveyor, 7 is a hopper, 8 is a middle cylinder, 9 is a gap for coke ash suction, 10 is the exhaust pipe, 1
1 is piping, 12 is a heat exchanger. 13 is piping, 14 is an exhaust gas fan, 15 is a dust collector, 1
6 is a pipe, 17 is a fan, and 18 is a burner 919 is a product removal device. ' 1/mm Continued from page 1 0 Inventor: Setsu Sueoka - 8-1, Goi Minamikaigan, Ichihara City, Japan Lime Industry Co., Ltd., Chiba Plant 0 Applicant: Nippon Lime Industry Co., Ltd., 4611 Isa, Isa-cho, Mine City 1

Claims (1)

[Claims] In a vertical firing device that co-fires raw materials and coke,
The raw material and coke are mixed uniformly and put into the furnace, and the overall combustion air rate of the burner is kept low to suppress the coke combustion speed, and the coke ash is pulverized and released from the boundary between the preheating zone and the firing zone. A firing method using a vertical firing apparatus, characterized in that combustion gas is taken out of the furnace together with the combustion gas.