JP2001201265A - Reduced iron discharge screw in moving hearth furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reduced iron discharge screw in a moving hearth furnace, capable of cooling an edge of a spiral flight heated to the highest temperature effectively by raising pressure of cooling water for avoiding deterioration in the cooling performance due to evaporation. SOLUTION: An edge spiral flight 32, constituting the edge of the spiral flight 3, can be cooled effectively by feeding high pressure cooling water to a circular cooling water passage 33, when the spiral flight 3 disposed on an outer periphery of a water-cooled rotation shaft 2 of the direct-reduced iron discharge screw 1 is constituted of a base end spiral flight 31 provided on the outer periphery of the water-cooled rotation shaft 2, and made by forming a plate member in a spiral form and the edge spiral flight 32 having the two circular water passages 33 having a circular cross section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a reduced iron discharge screw in a mobile hearth furnace for discharging reduced iron from the hearth of a mobile hearth furnace, and more particularly, to an improvement in an outer periphery of a water-cooled rotary shaft. The present invention belongs to the technical field of a reduced iron discharge screw in a mobile hearth furnace capable of effectively cooling a tip portion of a spiral blade which is exposed to the highest temperature.

[0002]

2. Description of the Related Art A movable hearth furnace has been conventionally used to reduce a pellet-like or briquette-like reduced iron material mainly composed of a carbon-based reducing material and iron oxide. There are two types of movable hearth furnaces, one constructed in a rotary circular shape and the other constructed in a straight shape. There is a reduced iron discharge screw that discharges to the area. The reduced iron discharge screw of the movable hearth furnace is exposed to a high-temperature atmosphere of, for example, 700 to 1200 ° C. or more, and directly contacts the reduced iron to move the reduced iron toward the side wall of the movable hearth furnace. The tip of the spiral blade has the highest temperature. Therefore, the tip portion of the spiral blade is severely worn and the durable life is shortened.In order to improve the durable life of the spiral blade, a wear-resistant layer is formed on the tip portion of the spiral blade, and the spiral blade is cooled with cooling water. I'm trying to cool.

As a reduced iron discharge screw in which a wear-resistant layer is formed at the tip of the spiral blade of the movable hearth furnace as described above, and the spiral blade is cooled by cooling water, for example, a United State Patent
No. 4,636,127 are known. Hereinafter, a schematic configuration of the reduced iron discharge screw of the movable hearth furnace according to this conventional example is shown in FIG. 7A in a side view and FIG. 7B in a cross-sectional view taken along line CC of FIG. ) And FIG. 8 of a cross-sectional view thereof will be described using the same reference numerals described in the publication.

[0004] Reference numeral 26 shown in the figure denotes a reduced iron discharge screw of a rotary type hearth furnace. The reduced iron discharge screw 26 includes a shaft 32 which is a water-cooled rotary shaft,
Six spiral blades 36 described later spirally provided on the outer periphery of the shaft 32, and pipes 62 provided on both sides of the shaft 32 and one of the pipes (right side in the drawing) 62 are fitted and joined. And a drive end 42 which is fitted and joined to the other couple end 40 and the other pipe (left side in the figure) 62.
The spiral blade 36 has a long bending member formed by bending a plate member into a U-shape, is formed in a spiral shape, and a base end side on an opening side is fixed to an outer periphery of the shaft 32 and a tip end portion thereof. Has a wear-resistant layer 44 formed thereon. The base end of the right pipe 62 is joined to a partition wall 60 provided in the shaft 32, and the base end of the left pipe 62 is joined to a partition wall 66 provided in the shaft 32.

Therefore, according to the reduced iron discharge screw 26 according to the conventional example, the cooling water flowing from the coupled end 40 flows through the right pipe 62 joined to the partition wall 60 and is provided on the pipe 62. Opening 52, shaft 3
8 flows into the spiral blade 36 through the right slot 46 in FIG. The cooling water that has cooled the spiral blades 36 passes through the left slot 46 and the opening 68 provided near the outer periphery of the partition 66 in FIG.
2 flows in the annular space 56 between the inner periphery of the inner tube 58 and the outer periphery of the inner tube 58 protruding from the partition wall 66 on the side opposite to the pipe 62 so as to be located inside the shaft 32.
To cool. Next, while being inverted by the inner surface of the partition wall 60, it passes through the opening 70 provided at the center of the partition wall 66, and flows out through the inside of the left pipe 62 and the left drive end 42.

[0006]

As described above, the reduced iron discharge screw of the movable hearth furnace according to the prior art has a wear-resistant layer formed at the tip of the spiral blade, and the spiral blade has a spiral blade. Since it is cooled by the cooling water flowing in the blade, it is considered that the blade has excellent high-temperature durability. However, in such a reduced iron discharge screw, it is preferable to more effectively cool the tip portion of the spiral blade, which comes into direct contact with the reduced iron and has the highest temperature. In order to effectively cool the tip of the spiral blade, it is necessary to increase the boiling point by increasing the water pressure to prevent evaporation of the cooling water.

However, in the case of the spiral blade of the reduced iron discharge screw according to this conventional example, as described above, a long bending member formed by bending a plate member into a U-shape is formed into a spiral shape. Due to the fact that the spiral blades are manufactured in such a manner, the plate thickness of the spiral blade cannot be so large. In other words, since the water pressure of the cooling water cannot be so high, the cooling performance may be reduced due to the local evaporation of the cooling water. It is necessary to insert a core to prevent the collapse of the space that becomes the water channel, and since the core must be removed from the twisted space after molding the spiral blade, the problem to be solved that the processing of the spiral blade is difficult is is there.

Further, since the cooling water flows through the entire inside of the spiral blade, the entire spiral blade is cooled, and the tip portion of the spiral blade with a large heat load cannot be preferentially cooled. In other words, if the tip portion of the spiral blade having a large heat load is to be cooled so as to be within a predetermined temperature range, in addition to the need for a larger amount of cooling water, the spiral blade which does not need to be cooled so much is required. As a result, the base portion and the shaft are excessively cooled, the entire reduced iron discharge screw becomes a cooling body, and the hearth of the mobile hearth furnace is excessively cooled, which may cause damage to the hearth. Absent.

Therefore, an object of the present invention is to make the cooling water higher in pressure in order to prevent the cooling performance of the spiral blade from deteriorating due to the evaporation of the cooling water. It is an object of the present invention to provide a reduced iron discharge screw in a movable hearth furnace, which makes it possible to effectively cool a tip portion of a spiral blade which becomes high in temperature.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances. Therefore, in order to solve the above-mentioned problems, a reduced iron discharge screw according to claim 1 of the present invention has been adopted. The feature of the invention is that a water-cooled rotary shaft attached to a movable hearth furnace for reducing reduced iron raw material and rotatably supported, and a plurality of spirally provided around the outer periphery of the water-cooled rotary shaft are provided. A reduced iron discharge screw in a movable hearth furnace, wherein the spiral blades spirally form a plate member, wherein the reduced iron on the hearth of the movable hearth furnace is discharged outside the furnace by rotation. The proximal spiral blade and the proximal side surface are fixed along the distal end surface of the proximal spiral blade,
The cooling water flowing into the water-cooled rotary shaft flows in from one end side, and returns to the inside of the water-cooled rotary shaft from the other end side.The tip spiral blade has a circular cooling water path having a circular cross section. is there.

A feature of the means adopted by the reduced iron discharge screw according to claim 2 of the present invention is that, in the reduced iron discharge screw in the movable hearth furnace according to claim 1, the circular cooling water passage is provided. , A plurality of tip spiral blades are provided in a direction from the tip end to the base end side.

A feature of the means adopted by the reduced iron discharge screw according to claim 3 of the present invention is that the reduced iron in the movable hearth furnace according to any one of claims 1 and 2 is characterized. In the discharge screw, the proximal spiral blade flows between the two spirally formed plate members and the proximal side surface of the distal spiral blade, and the cooling water flowing into the water-cooled rotary shaft flows in, This is where a rectangular cooling water passage having a rectangular cross section returning to the inside of the water cooling rotary shaft is formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reduced iron discharge screw according to a first embodiment of the present invention will be described with reference to FIG. And B in FIG.
This will be described with reference to FIG. 3 showing a sectional view taken along the line B and FIG. 4 showing a longitudinal sectional view thereof.

Reference numeral 1 shown in the figure denotes a first embodiment of the present invention.
2 is a reduced iron discharge screw of a mobile hearth furnace not shown in FIG. The reduced iron discharge screw 1 includes a hollow water-cooled rotating shaft 2 and a spirally provided 3 around the outer periphery of the water-cooled rotating shaft 2.
And a spiral blade 3 having a configuration to be described later. A partition plate 4 is provided at the right side in FIG. 4 corresponding to the end of the spiral blade 3 of the water-cooled rotary shaft 2. A radial center of the partition plate 4 is connected to a rotary joint 9 having a cooling water inlet 9a and an outlet 9b.
The cooling water return pipe 6 connected to the flange provided on the base end side penetrates watertightly.

An annular member 5 is located on the left side in FIG. 4 corresponding to the end of the spiral blade 3 in the water-cooled rotary shaft 2 and on the side of the partition plate 4 from the tip of the cooling water return pipe 6. Has been established. Between the inner surfaces of the partition plate 4 and the annular member 5 opposite to each other, ends of an inner cylinder 7 described later are joined in a watertight manner. A water passage hole 7 a penetrating from the outside to the inside is provided on the partition plate 4 side of the inner cylinder 7, and an annular space 8 is provided between the inner peripheral surface of the water-cooled rotary shaft 2 and the outer peripheral surface of the inner cylinder 7. Are formed. Further, the water-cooled rotating shaft 2
The opening end of the cooling water return pipe 6 at the front end side of the cooling water return pipe 6 is closed by fitting the closing plug 2b. I have. The cooling water return pipe 6 is formed of a flat plate that connects between the outer peripheral surface near the connecting portion of the cooling water return pipe 6 with the rotary joint 9 and near the tip and the inner peripheral surface of the water cooling rotary shaft 2. This is the supporting stay 10.

The spiral blade 3 is attached to the outer periphery of the water-cooled rotary shaft 2 along the spiral shape, as can be clearly understood from FIGS. 1, 2 and 3, and a base spiral formed by spirally forming a plate member. A blade 31, a distal spiral blade 32 having a proximal side fixed along a spiral distal surface of the proximal spiral blade 31, and a closing plate 2 a of the water-cooled rotary shaft 2 and a partition wall A cooling water inflow pipe 34 for flowing cooling water flowing from the rotary joint 9 into the tip spiral blade 32 between the plate 4 and the cooling water for cooling the tip spiral blade 32 is formed inside the water-cooled rotary shaft 2. A cooling water outflow pipe 35 for flowing out to the vicinity of the annular member 5 in the annular space 8.

The tip spiral blade 32 has a rectangular cross section, and two circular cooling water passages 33 are provided in parallel on the tip side and the base end side. The cooling water inflow pipe 34 is connected to the cooling water inlet side of the two circular cooling water paths 33, 33, and the cooling water outflow pipe 35 is connected to the cooling water outlet side. Of course, an abrasion-resistant layer 36 is formed which is continuous with the tip portion of the tip spiral blade 32 and the tip portion on one side on the side that directly contacts the reduced iron. In the first embodiment, as described above, two circular cooling water passages 33 are provided. However, even if one cooling water passage 33 is provided, a certain effect can be expected.

The tip spiral blade 32 is manufactured as follows. That is, two holes are drilled in parallel in a rectangular rod member having a substantially rectangular cross section and a predetermined length, and then formed into a spiral shape to manufacture a tip spiral blade unit. A plurality of such tip spiral blade units are joined to form one tip spiral blade 32 of a predetermined size. The spiral blade 3 may be configured such that a proximal spiral blade 31 is fixed to the outer periphery of the water-cooled rotary shaft 2 and then fixed to a distal spiral blade 32 on a spiral end face of the proximal spiral blade 31. Alternatively, after the tip spiral blade 32 is fixed to the spiral end face of the base spiral blade 31, the base end side of the proximal spiral blade 31 may be fixed to the outer periphery of the water-cooled rotary shaft 2.

The reduced iron discharge screw 1 having such a configuration is a portion of the reduced iron discharge screw 1 located in a movable hearth furnace (not shown), that is, as shown by a two-dot chain line in FIGS. Further, a refractory layer 11 made of an irregular refractory is formed on the outer periphery of the portion of the water-cooled rotary shaft 2 where the spiral blade 3 is provided. That is, the heat load of the water-cooled rotary shaft 2 is reduced by burying the base spiral blade 31 in the refractory layer 11.

The mode of operation of the reduced iron discharge screw 1 in the movable hearth furnace will be described below. The cooling water flowing from the inlet 9a of the rotary joint 9 is formed by the inner peripheral surface of the water-cooled rotary shaft 2 and the partition plate 4 The cooling water flows into a space formed between the first spiral blade 32 and the closing plate 2 a, and flows into each of the two circular cooling water passages 33 of the tip spiral blade 32 through the cooling water inflow pipe 34. It flows through the circular cooling water passages 33, 33 and the spiral blade 3
The cooling water that has cooled the tip spiral blade 32 of the
5, flows into the annular space 8 while cooling the water-cooled rotary shaft 2, flows toward the partition plate 4, flows into the inner cylinder 7 through the water passage hole 7a provided in the inner cylinder 7, and is closed. Stopper 2
It flows in the b direction. Next, the coolant flows into the cooling water return pipe 6 from the opening at the tip of the cooling water return pipe 6, and is discharged from the outlet 9 b of the rotary joint 9.

According to the reduced iron discharge screw 1 in the movable hearth furnace having the above-mentioned structure according to the first embodiment, the long bending member formed by bending the plate member into a U-shape is formed into a spiral shape. Unlike the reduced iron discharge screw of the movable hearth furnace according to the conventional example, which cools the entire spiral blade formed into a shape, the spiral blade 3 which is in direct contact with the reduced iron and has the highest temperature is used as described above.
Can be intensively cooled, and the circular cooling water passage 33 has a circular cross section, so that high-pressure cooling water can be supplied.
Therefore, there is an excellent effect that the possibility of local evaporation of the cooling water can be reduced, and excellent cooling performance can be exhibited over a long period of time. In addition, it is possible to adjust the flow velocity of the cooling water flowing through the two holes through which the cooling water flows into the circular cooling water passages 33, 33 of the cooling water outflow pipe 35.

Further, the cross-sectional shape of the circular cooling water passage 33 is formed in a circular shape as the name implies. Therefore, when the tip spiral blade 32 is formed into a spiral shape, the plate member is bent into a U-shape to form a cooling water passage between the plates, and the spiral blade of the reduced iron discharge screw according to the conventional example. Unlike this, since there is little possibility that the circular cooling water passage 33 will be crushed, there is also an effect of facilitating the manufacture of the spiral blade, which makes the spiral forming process easier than before.

The reduced iron discharge screw in the mobile hearth furnace according to Embodiment 2 of the present invention will be described below with reference to FIG. However, the difference between the reduced iron discharge screw according to the second embodiment and the first embodiment lies in the configuration of the tip spiral blade, so that the screw having the same function and the same function as the first embodiment is used. The same symbols are used and the differences are denoted by the same names. The tip spiral blade 32 of the reduced iron discharge screw 1 according to the second embodiment has a single circular cooling water passage 3.
3 and an inner tip spiral blade 32b having one circular cooling water passage 33. As shown in FIG. 5, the tip spiral blade 32 has a square member having a square cross section of a predetermined length, and one hole is formed in the square member to manufacture two types of spiral blade units having different spiral diameters. It was later overlapped and welded.

Therefore, the configuration of the tip spiral blade 32 of the reduced iron discharge screw 1 according to the second embodiment is the same as the configuration of the tip spiral blade according to the first embodiment. This is the same effect as in the first embodiment. However, the helical forming process of a square member of a predetermined length with one hole
Since it is easier than the spiral forming of a rectangular member having a rectangular cross section of a predetermined length in which two holes are formed, the welding process is increased, but the manufacturing cost of the spiral blade 3 is reduced and the above-described embodiment is performed. There is a cost reduction effect of being more economically advantageous than in the first mode.

A reduced iron discharge screw in a mobile hearth furnace according to Embodiment 3 of the present invention will be described below with reference to FIG. However, the difference between the reduced iron discharge screw according to the third embodiment and the first embodiment lies in the configuration of the spiral blade, and thus only the differences will be described.

That is, the reduced iron discharge screw 1 according to the third embodiment of the present invention, as can be clearly understood from FIG. 6, has a proximal spiral blade 3 spirally provided on the outer periphery of a water-cooled rotary shaft 2.
Reference numeral 1 denotes two plate members, and the water-cooled rotary member is disposed between the two plate members, the outer periphery of the water-cooling rotary shaft 2 and the base end surface of the tip spiral blade 32 having two circular cooling water passages 33. The cooling water flowing into the shaft 2 flows in through the cooling water inflow pipe, and the rectangular cooling water passage 37 having a rectangular cross section returning to the water-cooled rotary shaft 2 through the cooling water outflow pipe is formed. ing. Of course, the proximal spiral blade 31 composed of two plate members is buried in an unillustrated irregular refractory surrounding the water-cooled rotary shaft 2, similarly to the proximal spiral blade according to the first embodiment.

Therefore, according to the reduced iron discharging screw 1 according to the third embodiment, the base spiral blade 31 is composed of two plate members, and the plate member is formed in a U-shape as in the prior art. Instead of forming a cooling water passage between the plates by bending and forming the cooling water passage between the plates, the cooling water passage can be formed to have a preferable thickness if necessary. It can supply high-pressure cooling water and flow at a high flow rate.
Moreover, as described above, the base spiral blade 31 composed of the two plate members is provided with the refractory layer 1 formed on the outer periphery of the water-cooled rotary shaft 2.
Therefore, the reduced iron discharge screw 1 according to the third embodiment is the same as the reduced iron discharge screw 1 according to the first embodiment.

By the way, in the third embodiment, 2
Since the base portion of the tip spiral blade 32 can be indirectly cooled by the cooling water flowing through the angular cooling channel 37 formed between the two plate members, one circular cooling channel is provided at the tip portion. 33, the tip spiral blade 32
Can be cooled to the same degree as the tip spiral blade 32 according to the first embodiment. Therefore, in the comparison between the spiral forming cost and the welding cost of one plate member of the base spiral blade 31 and the drilling construction cost of one circular cooling water channel 33 of the distal spiral blade 32, the first embodiment is described. It is possible to expect an economic effect that it is more advantageous than the case.

In the above, as described above, the reduced iron discharge screw 1 provided with the three spiral blades 3 has been described as an example. However, even if the number of spiral blades 3 is four or more, the present invention is not limited thereto. Since such a technical idea can be applied, and three or more circular cooling water channels can be provided, the applicable range of the technical idea according to the present invention is limited by the first or second embodiment. It is not intended to limit the scope of the present invention, and design changes and the like can be freely made without departing from the technical idea of the present invention.

[0030]

As described in detail above, claim 1 of the present invention
The spiral blade of the reduced iron discharge screw in the movable hearth furnace according to any one of (1) to (3) is a base spiral blade obtained by spirally forming a plate member;
A circular cross-section is fixed to the base side surface along the distal end surface of the base spiral blade, and the cooling water flowing into the water-cooled rotary shaft flows in from one end and returns to the water-cooled rotary shaft from the other end. And a tip spiral blade having a circular cooling water passage.

Therefore, according to the reduced iron discharge screw in the movable hearth furnace according to claims 1 to 3 of the present invention, the long bent member formed by bending the plate member into a U-shape is used. Unlike the reduced iron discharge screw according to the conventional example, which cools the entire spiral blade formed in the above, it is possible to intensively cool the tip spiral blade which is the tip portion of the spiral blade which comes into direct contact with the reduced iron and has the highest temperature. It is possible to supply high-pressure cooling water with a circular cooling water passage having a circular cross section, so that the risk of local evaporation of the cooling water can be reduced, and excellent cooling performance can be exhibited over a long period of time. There is an excellent effect that can be.

Further, as described above, the cross-sectional shape of the circular cooling water passage is formed in a circular shape. When the tip spiral blade is formed in a spiral shape, the plate member is bent and formed in a U-shape. Unlike the spiral blade of the reduced iron discharge screw according to the conventional example in which the cooling water path is formed between the plates, there is little possibility that the circular cooling water path is crushed. There is also an effect of facilitating the manufacture of the spiral blade, which makes the spiral forming process easier than the spiral blade.

Further, according to the reduced iron discharge screw in the movable hearth furnace according to the second aspect of the present invention, since the tip spiral blade of the spiral blade is provided with a plurality of circular cooling water passages, the highest temperature is achieved. The tip spiral blade can be intensively cooled.

Further, according to the reduced iron discharge screw in the movable hearth furnace according to the third aspect of the present invention, the base spiral spiral blade of the spiral blade has a rectangular cross section having a rectangular cross section between two plate members. A water passage is formed, and the base side portion of the tip spiral blade can be indirectly cooled by the cooling water flowing through the angular cooling passage, so that the circular cooling water passage provided on the tip spiral blade is made one. be able to. Therefore, in comparison between the spiral forming cost and the welding cost of one plate member of the base spiral blade and the drilling work cost of one circular cooling water channel of the distal spiral blade, the movable hearth according to claim 1. An economic effect can be expected in that it can be manufactured at a lower cost than a reduced iron discharge screw in a furnace.

[Brief description of the drawings]

FIG. 1 is an explanatory side view showing a partially sectioned configuration of a reduced iron discharge screw according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line BB of FIG. 1 according to the first embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of the reduced iron discharge screw according to Embodiment 1 of the present invention.

FIG. 5 is a partial cross-sectional view of a reduced iron discharge screw according to Embodiment 2 of the present invention.

FIG. 6 is a partial cross-sectional view of a reduced iron discharge screw according to Embodiment 3 of the present invention.

7 (a) is a side view of a reduced iron discharge screw of a movable hearth furnace according to a conventional example, and FIG. 7 (b) is a side view of FIG.
It is a CC sectional view taken on the line of (a).

FIG. 8 is a sectional view of a reduced iron discharge screw of a movable hearth furnace according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reduction iron discharge screw 2 ... Water-cooled rotating shaft, 2a ... Closure plate, 2b ... Closure plug 3 ... Spiral blade, 31 ... Base end spiral blade, 32 ... Tip spiral blade, 32a ... Inner tip spiral blade, 32b ... Outer tip Spiral blade, 33: circular cooling water passage, 34: cooling water inflow pipe, 3
DESCRIPTION OF SYMBOLS 5 ... Cooling water outflow pipe, 36 ... Wear resistant layer, 37 ... Square cooling water channel 4 ... Partition wall 5 ... Annular member 6 ... Cooling water return pipe 7 ... Inner cylinder, 7a ... Water passage hole 8 ... Annular space 9 ... Rotary Joint 9a Inlet 9b Outlet 10 Stay 11 Refractory layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F27D 3/08 F27D 3/08 F term (reference) 4K001 AA10 BA02 CA23 GA07 GB01 GB02 4K012 CA08 DE08 4K050 AA01 BA02 CA01 CA08 CA17 CG21 4K055 AA00 AA05 DA05 4K061 AA01 AA08 BA02 EA03 EA07

Claims (3)

[Claims] A rotatable water-cooled rotary shaft attached to a movable hearth furnace for reducing reduced iron raw material, and a plurality of rotatable shafts attached to the outer periphery of the water-cooled rotary shaft along a spiral shape. A reduced iron discharge screw in a movable hearth furnace, which comprises a spiral blade and discharges reduced iron on the hearth of the movable hearth furnace out of the furnace by rotation, wherein the spiral blade is formed by spirally forming a plate member. The end spiral blade, the base side surface is fixed along the distal end surface of the base spiral blade, cooling water flowing into the water-cooled rotary shaft flows in from one end side, and the water-cooled rotary shaft And a tip spiral blade having a circular cooling water passage having a circular cross section. 2. The reduced iron discharge in a movable hearth furnace according to claim 1, wherein a plurality of said circular cooling water passages are provided in a direction from a tip end side of said tip spiral blade to a base end side. Screw. 3. The proximal spiral blade is provided between two spirally formed plate members and a proximal side surface of the distal spiral blade.
While the cooling water flowing into the water-cooled rotating shaft flows in,
The reduced iron discharge screw in the movable hearth furnace according to any one of claims 1 and 2, wherein a rectangular cooling water passage having a rectangular cross section returning to the water-cooled rotary shaft is formed. .