JPS6141395B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating method for preheating raw material charged into an electric furnace, such as scrap, using exhaust heat of the electric furnace.

Originally, the exhaust gas from an electric furnace has a huge amount of heat, and if it were to be led directly to a dust collector, it would be at such high temperature that it could burn out. However, it not only causes a loss of thermal energy but also requires a great deal of effort for cooling. For this reason, attempts have been made to preheat the charged scrap as an effective use of this thermal energy, but installing a bucket in the middle of the flue and simply filling and heating the scrap in this bucket increases pressure loss and increases electricity consumption. Due to insufficient suction pressure of exhaust gas into the furnace, there is a risk of exhaust gas leaking from around the electric furnace.

In view of this, the present invention aims to provide a novel preheating method that improves the preheating effect without affecting the suction wind pressure. The invention will be specifically explained.

In the figure, exhaust gas generated in an electric furnace A is guided by the suction force of a suction fan F to a combustion chamber 4 via an exhaust duct 3 provided in a furnace lid 1 or a main body 2. At this time, if necessary, a gap 5 is provided to draw in secondary air and ensure complete combustion.

The exhaust gas completely combusted in the combustion chamber 4 is sent to a preheating device B (described later) through an underground duct 6 covered with a heat insulating material, where the charged scrap is preheated and its temperature is lowered by heat exchange. After that, the dust is sucked by a suction fan F, and is force-fed to the dust collector 7, and after dust removal, it is discharged outdoors.

The preheating device B includes a cylindrical bucket main body 10,
The main body 10 is mainly composed of a bottom cover 20 attached to the lower part of the main body and a top cover 30 attached to the upper part of the main body, and the main body 10 has protective bars 12 established at appropriate intervals on the inner surface of a wall 11 made of a heat-resistant material. The bottom cover 20 is designed to protect the wall 11 and reduce the frictional resistance when the filling material falls. 24, and the left and right unit members are normally connected by appropriate means to form a funnel shape, but when necessary, each unit member is released and opened to the left and right to release the scraps stored in the main body. A plurality of openings 25 are provided at the bottom of the bottom cover, and a closing collar is provided around the lower part to fit into a sand seal groove 41 provided in a pedestal 40 connected to the underground duct 6. 26 are provided.

The main body 10 is filled with raw material scrap, but in order to minimize the flow resistance to the exhaust gas of the electric furnace and to expand the heat receiving area, the bottom cover 20 is
An exhaust gas flow hole c communicating with the opening 25 is bored.

The drilling of the communication hole c is carried out on the traveling truck 50, on which a plurality of bars 51 are installed that pass through the opening 25, and the bottom cover 20 is attached. The main body 10 is placed on the cart 50, and the bar 51 is passed through the opening 25. Next, the raw material scrap W is transported by a lifting magnet 52 or the like and filled into the main body, and is pressurized by the lifting magnet 52 or other means. Next, the cart is moved along the rail 53 to the pedestal 40.
Move nearby and lift the main body 10 using the crane 60. As a result, the bar 51 remains on the cart and the main body 10 is pulled up from the bar 51, and a large number of exhaust holes c communicating with the opening 25 are formed in the filled raw material scrap W. Then, while maintaining this state, the main body 10 is moved onto the pedestal 40, the flange 26 of the bottom lid 20 is inserted into the sand seal groove 41, and the upper lid 30 is placed, and the closing flange 3
1 into the sand seal groove 13 on the top of the main body and seal it.

Figures 3 to 5 show an example in which two of the above-mentioned bodies are arranged in parallel, and one body is used to perform the above-mentioned scrap filling operation on the other body, and the scrap filling operation is performed on the other body while the other body is in use. The traveling carts 50a, 50
b, and the upper lid 30 has both main bodies 10a, 1
It is provided at the tip of a swing arm 70 that communicates with the fan F so as to be used in common with the fan F.

In the figure, 71 and 72 indicate switching dampers, respectively.

To explain the relationship between the above two preheating devices and the electric furnace operation pattern with reference to FIG. 5, the first preheating device
The raw material scrap preheated by B ₁ is put into an electric furnace, and the second preheating device B ₂ side is heated by the waste heat generated from the electric furnace, and during this time, the raw material is put into the first preheating device B ₁ . do.

Next, the raw material in the second preheating device _B2 is additionally charged into the electric furnace, and the exhaust passage is switched to the first preheating device _B1 . After operating the electric furnace for the required time, one charge is completed by allowing the melted raw material to flow out. This is repeated thereafter.

When using the method of the present invention, raw material scrap is filled in the cylindrical body of the preheating device by forming a large number of exhaust ventilation holes, and the exhaust heat of the electric furnace is passed through these holes to heat them, so there is no back pressure on the exhaust gas. Moreover, the heat transfer area is expanded and waste heat is effectively absorbed, which not only makes effective use of thermal energy but also helps reduce the amount of cooling water used for cooling. It has excellent effects such as being able to extend the lifespan of these devices.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the main parts of the present invention, Fig. 2 is a longitudinal cross-sectional view of the main parts during filling of raw materials, Fig. 3 is an overall explanatory view showing the mode of implementation, Fig. 4 is a plan view thereof, and Fig. 4 is a plan view thereof. FIG. 5 is a graph for explaining the related operation between the preheating device and the electric furnace operation pattern. B... Preheating device, C... Exhaust flow hole, W... Raw material scrap, 10... Bucket main body, 51...
bar.

Claims (1)

[Claims] 1. Place the cylindrical preheating device main body into which the raw material is placed on a cart equipped with a plurality of bar materials at intervals, and after filling the main body with the charged raw material, the main body is pulled out from the bar material and exhausted. 1. A method for preheating raw material to be charged in an electric furnace, comprising forming a flow hole, disposing the main body in an electric furnace exhaust passage, and introducing exhaust gas into the flow hole to heat the raw material to be charged.