JPS5930988B2 - Iron powder drying equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to an iron powder drying device.

Various drying devices are known for drying iron powder, but
Most of the time, the atmosphere inside the drying equipment is not an inert gas atmosphere (for example, N2*Ar gas), so the oxidation rate of iron powder during the drying process is high and the oxygen value of the iron powder after drying increases.
In order to improve the quality of iron powder, it is necessary to perform gas reduction in a reduction furnace in the next process, which results in a large consumption of reducing gas and a longer reduction time, which reduces the processing capacity of the equipment. There was a drawback.

In order to avoid the above-mentioned drawbacks, devices for drying iron powder in an inert gas atmosphere have been proposed, but these devices have the disadvantage that the amount of inert gas consumed is too low.

The purpose of the present invention is to provide an iron powder drying device that eliminates and improves the above-mentioned drawbacks of conventional iron powder drying devices,
The said object can be achieved by the device according to the claims.

Next, the present invention will be explained in detail.

The iron powder drying device of the present invention is a drying device having an indirect heating type rotary drum type dryer, and is a method in which heat is transferred to the wet iron powder to be dried through a steam tube placed inside the rotating drum type dryer to dry it. However, in the device of the present invention, the amount of gas flowing through the drum-type dryer only needs to be the amount necessary to carry the evaporated moisture out of the drum, so the amount can be small, and the amount of exhaust gas is small, so it can be used for exhaust treatment. The Iro Scrubber is characterized by being small in size and requiring less amount of inert gas to prevent oxidation of iron powder during the drying process.

Next, the apparatus of the present invention will be explained with reference to the drawings.

As shown in Figure 1, the device of the present invention consists of a drum in which a large number of steam tubes are arranged concentrically along the inner circumferential surface of a drum through which high-temperature steam is introduced, and a circulating inert gas is introduced into the drum. The dryer 1 is tilted and supported so as to be removable, and each pipe line and each sliding part on the supply side and discharge side of the iron powder connected to the drum are closed by airtight contact with valve installation. , a duct 5 connecting the scrubber 2, the heater 3, the blower 4, and the filling equipment;
6, 7, 8, and 9 are connected to the output side of the dryer 1 to form a closed circulation circuit for circulating generated water vapor and inert gas.

The dryer 1 is provided with a supply valve 10 and a feeder 11 for supplying wet iron powder.

The dryer 1 is supported by two sets of rollers 12 so that its axial direction is inclined, and a gear 13 driven by a motor 14 is mounted on the outer periphery of the dryer 1.

The iron powder in the dryer 1 is stirred by rotation,
Scraping blades 15 and guide blades 16 are provided in and in contact with the dryer 1, respectively, for supplying the iron powder that has been moved to the lower end of the dryer 1 and has reached the lower end to the discharge port 17.

At the exhaust port 17, together with the iron powder supply valve 10, an iron powder discharge valve 18 is provided which can shut off the atmosphere during drying from the atmosphere.

Inside the dryer 1, as shown in Fig. 3, there are a number of concentric pipes (3 concentric pipes) that conduct high temperature steam inside.
A tube 19 (showing an example of a double tube arrangement) is disposed, and one end of this tube has a rotary joint 20 for supplying steam into the tube and a steam port 2.
1 are connected to each other, and a drain outlet 22 and a drain trap 23 for discharging the steam circulating in the tube 19 inside the dryer 1 are also connected to each other.

The sliding parts of the rotating part and the fixed part of the dryer 1, that is, the supply side sliding part 24 and the discharge side sliding part 25, are connected in a closed sliding manner to prevent outside air from entering the dryer. An event 9 for supplying inert gas to the dryer is connected to the supply side sliding part.

A duct 5 is installed in the scrubber 2 to connect the dryer 1 with the scrubber 2 that processes the moisture that evaporated in the dryer. A spray nozzle 26 is provided to spray water to remove the fine iron powder entrained in the scrubber 2, and a seal bot 27 is provided at the bottom of the scrubber to discharge the waste water inside the scrubber 2 to the outside of the system.
is provided.

In order to reuse the inert gas introduced into the scrubber 2 together with the evaporated moisture, a duct 6 is connected to the upper part of the scrubber 2 to draw out the gas, and a duct 6 is further connected to this duct to remove the inert gas from the moist inert gas. A heater 3 for preventing condensation of moisture in the air, a blower 4 for supplying the gas indirectly heated by steam in the heater 3 to the dryer 1 again, and a duct 9 for connecting the blower and the dryer are provided.

This duct 9 is provided with a valve 29, an atmosphere suction valve 30, an inert gas suction valve 31, and a branch discharge pipe 8 for discharging to the atmosphere, and this discharge pipe 8 is further provided with a discharge valve 28. ing.

Next, an example of the operating method of the present invention will be described.

Example: The blower 4 is operated by closing the valves T0.18 and T29.30 and opening the valve 28.

When the valve 31 is opened, an inert gas is introduced into the device, and the gas inside the device is released into the atmosphere through the discharge pipe 8.

Furthermore, the inert gas is compressed from the sliding part 24 and 25 and the discharge pipe 8
The oxygen concentration in the gas released from the gas is measured by an appropriate method, and when the concentration is below a predetermined value, the valves 28 and 31 are closed and the blower 4 is stopped.

In the embodiment of the present invention, the oxygen concentration in the released gas is 0.01~
0.001% and the time required for replacement is 10-40
The amount of inert gas required was 20 to 5 ONm3.

The dryer 1 is rotated clockwise when viewed from the supply side, the feeder 11 is operated, the supply valve 10 is opened, and the iron powder with moisture attached is supplied to the supply valve 10 by an appropriate method.

The moisture content was 8 to 11 percent by weight, and the iron powder weight was 2 to 8 tons on a dry basis.

When the supply is finished, the supply valve 10 is closed and the feeder 11 is closed.
stop.

The dimensions of the dryer 1 are diameter 2.400mm, length of the straight body 4.
．． The total outer surface area of the internal tube, that is, the heat transfer area is 130R, and the motor 14 can rotate in any direction by changing the rotation direction, and the rotation speed is 3 rpm.
The slope was 3/1oo.

When rotating clockwise as seen from the supply side, the raking blade 15
However, the iron powder is not scraped up and remains in the dryer 1 while being stirred.

In the case of the counterclockwise direction, the iron powder is scraped up by the scraping blades 15, collected at the center line of the dryer 1, and sent to the discharge port 17 by the guide blades 16.

Therefore, when the supply is finished and the dryer 1 is rotating clockwise when viewed from the supply side, the wet iron powder is transferred to the dryer 1.
It is located at the bottom of the tube 19 and is in contact with the tube 19 for stirring.

Here, when steam is passed through the steam port 21 of the rotary joint 20, the steam passes through the tube 19.

The steam heats the iron powder through the tube 19 and is cooled to become drain, passing through the drain outlet 22 of the rotary joint 20 and being discharged from the drain trap 23.

The iron powder is heated and the water evaporates.

When the blower 4 is operated and the valve 29 is opened, the gas and evaporated water in the dryer 1 pass through the duct 5 and enter the lower part of the scrubber 2.

When cooling water is sprayed into the scrubber 2 through the nozzle 26, the gas and moisture are cooled, the moisture condenses into water, and the dust entrained in the gas is also removed.

These cooling water, condensed water, and dust overflow from the seal pond 27.

The gas, whose temperature and absolute humidity have decreased, passes from the top of the scrubber 2 through a duct 6, is heated by a heater 3, is pressurized by a blower 4 from a duct 7, and is returned to the dryer 1 through a duct 9.

Gas temperature in duct 5 is 85-95℃, 20℃ in duct 6
-40°C, 50-80°C in duct 9.

The oxygen concentration in the circulating gas is measured midway through the duct 9, and if it is higher than a predetermined concentration, the valve 31 is opened to replenish inert gas into the system.

By an appropriate method, it is detected that the iron powder has dried, the steam supply is stopped, and the blower 4 and dryer 1 are also stopped.

Reinforcement and sliding part 24.2 by inert gas valve 31
Replenishment of inert gas from No. 5 is also stopped.

The time required for drying is 20 to 60 minutes, and the amount of inert gas consumed is 5
0 to 30 ONm"Hr, oxygen concentration in circulating gas is 0.
It was 01-o, ooi percent.

Next, open the valve 18 by reversing the motor and dryer 1.
Rotate counterclockwise when viewed from the supply side to discharge and discharge dry iron powder.

When the iron powder is almost completely discharged from the dryer 1, stop the dryer 1 and close the valve 18.

The time required for evacuation was 20-40 minutes.

When iron powder is dried in an inert gas atmosphere using the apparatus of the present invention, the oxygen value of the iron powder before drying is 6000 PPM, which remains the same as 6000 PPM after drying, as shown by the broken line A in Figure 2. When drying without creating a gas atmosphere, solid lines B in the figure (inert gas is filled in the piping at the beginning of operation, but no inert gas is added for the purpose of suppressing oxygen concentration after that), C As shown in (carried out in an oxidizing atmosphere without using an inert gas), the oxygen value of the iron powder after drying becomes extremely high.

As described above, when iron powder is dried using the apparatus of the present invention, iron powder with a low oxygen value can be efficiently produced with a small amount of inert gas consumption.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the iron powder drying apparatus of the present invention, Figure 2 is a diagram showing changes in oxygen value before and after drying iron powder, and Figure 3 is a diagram showing the dryer's static state and drying rotation state. FIG. 1... Dryer, 2... Scrubber, 3... Heater, 4... Blower 15, 6, 7, 9... Duct, 8... Discharge pipe, 10... Supply valve, 11...
・Feeder, 12...Roller, 13...Gear, 14
... Motor, 15 ... Scraping blade, 16 ... Guide vane, 17 ... Discharge port, 18 ... Discharge valve, 1
9...Tube, 20...Rotary joint,
21...Steam inlet, 22...i drain outlet,
23...Drain lamp, 24...1 side sliding part, 25
...Discharge side sliding part, 26...Spray nozzle, 27
...Seal pot, 28...Release valve, 29...
- Circulation valve, 30...Atmospheric suction valve, 31...Inert gas suction valve.

Claims (1)

[Scope of Claims] 1 A drum having a plurality of steam tubes arranged concentrically along the inner circumferential surface of a drum into which circulating inert gas is introduced, through which high-temperature steam is conducted; A tilt-supported dryer for transferability, in which each pipe line and each sliding part on the supply side and discharge side of iron powder connected to the iron powder are sealed by installing a valve or by airtight contact, and the dryer has moisture to be dried in the dryer. A scrubber removes water vapor from a mixed gas of steam generated from iron powder and a circulating inert gas, a heater for heating the circulating inert gas, and a heated circulating inert gas is returned to the iron powder discharge side of the dryer. A gas processing circuit for treating generated steam and circulating inert gas by connecting a blower for supplying a blower to the dryer and the dryer through a duct to form a closed circuit, and a Karanaro iron powder drying apparatus.