JPS6113158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for recovering waste heat in a firing furnace using a traveling grate.

In a great kiln type kiln that burns iron ore pellets, a traveling grate, or a great conveyor consisting of a grate plate and chain, is used to transport the pellets while drying and water-repelling them, as a step before being baked in a rotary kiln at approximately 1300°C. , three steps of preheating are performed. The temperature of the above-mentioned great conveyor rises to approximately 500℃ in the final (preheating process), and conventionally, the sensible heat of this conveyor is dissipated into the atmosphere on the return journey of the conveyor, causing a large amount of energy loss. was.

The present invention recovers the sensible heat of this great conveyor, and its feature is that the high temperature area on the return side of the great conveyor is surrounded by a hood, air is taken into the hood, and heat is exchanged between the air and the conveyor. The best part is that it can be extracted as hot air. The present invention also provides an air intake port by opening both ends of the hood in the conveyor traveling direction, opening the center of the hood to attach a hot air outlet pipe, and furthermore, sandwiching the conveyor in the hood to form an air intake port. It is characterized by the fact that baffle plates are installed in a staggered manner at the bottom.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

The processing process of iron ore pellets in a kiln using a traveling grate shown in Fig. 1 is the same as the conventional one, and the pellets are fed from the upstream side onto the grate conveyor 1 which circulates in the direction of the arrow in the figure. A drying chamber 2, a separation chamber 3, and a preheating chamber 4 are successively provided from the upstream side to the downstream side of the conveyor while being conveyed downstream by a great conveyor.
After drying, water separation, and preheating, the material is put into a rotary kiln 5 connected to the downstream end of the great conveyor 1, where it is fired and then transported to a cooler 6.

In the above kiln, the rotary kiln 5 burns the pellets at about 1300°C using the burner 7, and in the preheating chamber 4 communicating with the rotary kiln 5, the heat introduced from the rotary kiln 5 burns the pellets at about 1000°C.
The pellets are preheated at a temperature of about 400°C, and the upstream water separation chamber 3 communicates with the preheating chamber 4 via an air conduit 8, and the pellets are separated at about 400°C by the heat introduced from the preheating chamber 4.
Furthermore, the drying chamber 2 on the upstream side similarly communicates with the separation chamber 3 via the air duct 9, and the pellets are dried at approximately 200°C using the heat introduced from the separation chamber 3. The waste gas is discharged to the outside through the discharge line 10.

The temperature of the great conveyor at the portion where it passes through the preheating chamber 4, turns around, and enters the return path (return side high temperature area) is as high as about 500°C.

Therefore, in the present invention, a heat recovery device 20 as shown in FIG. 2 is provided in the high temperature area on the return side of the great conveyor.

In other words, in FIG. 2, the circulating chain 21 is provided with a grate plate 2 in the width direction and the traveling direction.
A hood 23 that surrounds the upper side, lower side, and both left and right sides of the conveyor is provided in the return side high temperature area of the great conveyor 1 configured to have the conveyor belt 2 attached thereto, and the hood 23 blocks outside air.

Both ends of the hood 23 in the direction of conveyor movement are opened to form an air intake port 24;
A hot air outlet 25 is formed by opening the central part of the
A hot air outlet pipe 26 is connected to the outlet. A fan 11 is connected to the hot air extraction pipe to suck hot air.

Inside the hood 23, baffle plates 27 are installed in a staggered manner at the upper and lower parts of the conveyor 1.

With such a configuration, the fan 11
The air sucked in by the air intake port 24 passes between the conveyors by the baffle plate 27, exchanges heat with the conveyor, and passes through the hot air outlet pipe 26 to the hood 2.
3. Be led outside. This hot air is used as process gas, kiln burner primary air, or cooler cooling air. In FIG. 1, 12 is a connection pipe to the air blowing path 9 to the drying chamber when used as a process gas, and 13 is a connection to the burner primary air pipe when used as kiln burner primary air. Further, 14 is a connecting pipe line to a cooling air pipe line when used as cooling air for a cooler.

Next, an example of waste heat recovery when the present invention is applied to iron ore pelletizing equipment using a great kiln system with a production capacity of 350 tons per hour will be described.

● Weight of great conveyor 1.123Kg/Kg - pellets ● Temperature before heat recovery of 〃 500℃ ● Temperature after heat recovery of 〃 400℃ ● Specific heat of 〃 0.11kcal/Kg・℃ Therefore, recovered heat amount Q = 1.123× (500-400) x 0.11 = 12.35 kcal/Kg - pellets. This recovered heat amount is equivalent to the total fuel consumption of the pelletizing equipment (120 to 130k for magnetite).
cal/Kg - Approximately 250kca for pellets and hematite
1/Kg-pellets), it accounts for 5-10% of the total
The waste heat recovery effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing a great kiln type iron ore pelletizing equipment to which the present invention is applied;
The figure is a diagram showing details of the heat recovery device. 1: Great conveyor, 2: Drying room, 3: Separation room, 4: Preheating room, 5: Rotary kiln, 6: Cooler, 7: Burner, 8, 9: Air duct, 1
0: Release pipe, 11: Fan, 12, 13, 1
4: Connection pipe line, 20: Heat recovery device, 21: Chain, 22: Grate plate, 23: Hood, 2
4: Air intake, 25: Hot air outlet, 26: Hot air outlet pipe, 27: Baffle plate.

Claims (1)

[Claims] 1. A hood surrounds the high temperature region on the return side of a grate conveyor of a kiln using a traveling grate, and air is taken into the hood to exchange heat between the air and the conveyor, and then taken out as hot air. A waste heat recovery method in a kiln furnace using a characteristic traveling grate. 2. A hood that surrounds the conveyor in the high temperature range on the return side of the grate conveyor of a kiln using a traveling grate, an air intake port formed by opening both ends of the hood in the direction of conveyor movement, and an air intake opening formed in the center of the hood. In a firing furnace using a traveling grate, which comprises a hot air take-off pipe attached to an opening of a lever, and baffles are installed in a staggered manner at the upper and lower parts of the hood with a conveyor sandwiched therebetween. Waste heat recovery equipment.