JPH05171216A - Treating device for discharged gas and liquid of half-calcination furnace for powder metallurgical molding - Google Patents

Abstract

PURPOSE:To safely and stably treat the binder discharge gas and liquid from a half-calcination furnace. CONSTITUTION:A binder liquid discharge pipe 6 is provided in the bottom 2 of the half-calcination furnace 1 for powder metallurgical moldings. The other end of this discharge pipe 6 is connected via a valve 10 to a binder liquid recovering container 15 having a hermetic structure. A gas discharge pipe 7 for binder vapor, etc., is connected near to the bottom of the side wall 4 of the half-calcination furnace 1 and the other end of this discharge pipe 7 is connected via a valve 21 to a burner 22. The binder discharge gas and liquid are thus separated and are separately treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating a gas or liquid discharged from a binder or the like in a semi-firing furnace for powder metallurgical moldings.

[0002]

2. Description of the Related Art In the process of manufacturing powder metallurgical products, a molded product obtained by mixing iron powder, carbide powder, oxide powder, etc. with a binder of a polymer organic solvent is molded in a reducing atmosphere in a semi-firing furnace. There is a step of firing to escape the binder.
In this semi-baking furnace, the binder is melted out of the molded body and becomes a gas-liquid (vapor and liquid) due to the temperature rise. Therefore, this gas-liquid is taken out of the furnace for processing.

Conventionally, there is a device shown in FIG. 3 as a device for treating the discharged gas and liquid. In FIG. 3, 31 is a powder metallurgical compact semi-firing furnace, 32 is a furnace bottom, 33 is a gas-liquid discharge pipe connected to a side wall 34 near the furnace bottom, 35 is a valve provided in the middle of the discharge pipe 33, A combustor 36 is connected to the other end of the discharge pipe 33, an unburned binder liquid recovery container 38 filled with cooling water 37 is provided at the bottom of the combustor 36, and the unburned binder liquid is placed on the cooling water 37.
39 is set to accumulate. Further, 40 is an auxiliary combustion pilot burner, 41 and 42 are dilution air supply pipes, 43 is a combustion exhaust gas duct, and 44 is a dust collector provided in the middle of the duct 43.

In the conventional apparatus, the gas-liquid and reducing gas of the binder, which are melted from the compact in the semi-baking furnace 31, are both discharged from the gas-liquid discharge pipe 33 to the outside of the furnace 31 and guided to the combustor 36. Is ignited and burned by the auxiliary combustion pilot burner 40,
The combustion exhaust gas is diluted by the air from the dilution air supply pipes 41, 42, passes through the exhaust gas duct 43, is dust-removed by the dust collector 44, and is then released outdoors. On the other hand, the binder liquid 39 that has not been completely burned by the combustion of the exhaust gas liquid is recovered by the unburned binder liquid recovery container 38 and cooled by the cooling water 37.

[0005]

By the way, in the above-mentioned prior art, since the binder liquid, the vapor and the reducing gas are simultaneously combusted in the combustor 36, a high concentration of the binder liquid, as shown in FIG. There is a problem that soot (smoke) is generated and the binder liquid cannot be completely burned. The high-concentration soot dust is collected by the dust collector 44, but it adheres and accumulates on the inner surface of the exhaust gas duct 43 up to the dust collector 44, becomes dust by some shock, and the combustion conditions (combustibles, oxygen, heat) are uniform. In that case, a dust explosion accident similar to aluminum powder or magnesium powder may occur.

Therefore, the exhaust gas duct 43 must be regularly cleaned by stopping the operation of the semi-baking furnace so that dust and dirt do not adhere and accumulate, which is also a problem in terms of production. On the other hand,
The binder liquid that does not burn up in gas-liquid mixed firing falls on the cooling water 37 in the container 38 and is collected, but if the amount of cooling water 37 is too small or if the cooling water 37 is forgotten to be put in the container 38, the cooling water
The unburned binder liquid 39 dropped on the 37 is overheated by the radiant heat of the gas-liquid combustion flame in the upper part to be vaporized, and the unburned binder liquid 39 on the container 38 is transferred from the upper combustion flame to burn. The heat load is higher than the design conditions of the auxiliary equipment and the incidental equipment causes a burnout accident of the auxiliary equipment.Furthermore, the thermal condition of the combustion conditions of the dust explosion described above is satisfied, and the probability of the dust explosion occurs. There are problems such as becoming expensive.

The present invention has been made in view of the above situation, and an object thereof is to safely and stably treat a gas / liquid discharged from a semi-firing furnace of a powder metallurgical compact, An object of the present invention is to provide an exhaust gas / liquid treatment device capable of preventing dust generation, dust explosion, and accidental burnout of incidental equipment, and achieving environmental disaster prevention and productivity improvement.

[0008]

In order to achieve the above object, the present invention takes the following technical means. That is, the present invention is an apparatus for separating a liquid of a molding binder discharged from a semi-firing furnace of a powder metallurgical molded body and a gas such as vapor, and incinerating the gas, wherein the binder is added to the bottom of the semi-firing furnace. A liquid discharge pipe is provided, the other end of the discharge pipe is connected to a binder liquid recovery container, a gas discharge pipe of binder vapor or the like is connected to the lower side wall of the semi-baking furnace, and the other end of the gas discharge pipe is connected to a combustor. It is characterized by connecting and connecting valves to both discharge pipes.

Further, the present invention is characterized in that at least one or both of the binder liquid discharge pipe and the gas discharge pipe is heated and kept warm. Further, the present invention is characterized in that the binder liquid recovery container has a closed structure, nitrogen gas is supplied into the container, and the combustible gas in the container is led to a semi-firing furnace or a combustor through a gas vent pipe. ..

[0010]

The densities of the binder liquid and vapor and the reducing gas in the semi-firing furnace are smaller in the order of liquid, vapor and reducing gas, and are divided into upper and lower parts due to the difference in density. According to the present invention, the liquid of the binder and the vapor and the gas of the reducing gas are taken out by separate discharge pipes, and the liquid having a high density is dropped on the bottom of the furnace and is quickly recovered outside the furnace without being vaporized. Since the binder liquid is less carburized, quality deterioration can be prevented, and the liquid vaporization time can be saved, thus improving the productivity.

On the other hand, the gas of the binder is guided to the combustor by the gas discharge pipe, and is completely combusted there. No gas-liquid mixed combustion occurs and no soot dust is generated, so that the gas is directly discharged into the atmosphere. Further, according to the present invention, the binder liquid discharge pipe is heated and kept warm, so that the binder liquid can be kept at the optimum heat holding temperature to improve its fluidity and be smoothly discharged to the recovery container. .. By heating and keeping the gas discharge pipe warm, the binder vapor is not liquefied and gas-liquid mixed firing does not occur, so it is possible to prevent the generation of soot and smoke.

Further, according to the present invention, since the binder liquid recovery container has a closed structure and is replaced by supplying nitrogen gas, the combustible gas in the container does not leak outside.
In addition, the combustible gas generated in the binder liquid recovery container is guided into the semi-firing furnace by the gas vent pipe, promotes discharge of the binder liquid, and is burned from the gas discharge pipe to the combustor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a semi-firing furnace for powder metallurgical moldings,
The bottom 2 is provided with a binder liquid outlet 3 and
The furnace bottom 2 is inclined so that it becomes lower toward the discharge port 3 so that the binder liquid can be collected and discharged quickly and smoothly, and the gas discharge port 5 is provided near the furnace bottom 2 on the side wall 4.
Is provided, and the binder liquid discharge pipe 6 and the gas discharge pipe 7 are detachably connected to the discharge ports 3 and 5, respectively.

Since the densities of the binder liquid, vapor and reducing gas in the semi-baking furnace 1 become smaller in the order of liquid, vapor and reducing gas, the density difference of the binder in the semi-baking furnace 1 is By utilizing this, the liquid and the vapor and the gas of the reducing gas can be separately discharged. The binder liquid discharge pipe
A heat-retaining heater 8 (spiral sheath electric heater) and a temperature control sensor (not shown) are attached to the outer circumference of the 6 and heat-insulating material 9 is used to reduce heat loss.
And a valve 10 is provided on the way.
In addition, in the discharge pipe 6, a gas vent pipe is installed from the upper side of the valve 10.
11 is inserted, and the upper end of the gas vent pipe 11 is inserted into the semi-firing furnace 1, and a valve 12 is provided at a portion of the gas vent pipe 11 exposed from the exhaust pipe 6, A heat retaining heater 13 (spiral sheath electric heater) and a temperature control sensor (not shown) are attached to the outer periphery, and a heat retaining material 14 is coated to reduce heat loss.

The other ends of the binder liquid discharge pipe 6 and the degassing pipe 11 are detachably connected to an openable / closable sealing lid 16 of the binder liquid recovery container 15, and the binder liquid is recovered in the container 15. The combustible gas in the container 15 is led out into the semi-baking furnace 1 through the gas vent pipe 11. A nitrogen gas supply pipe 18 is connected to the closed lid 16 of the binder liquid recovery container 15 via a valve 17, and it is dangerous if the vaporized combustible gas of the binder liquid leaks to the outside. It is designed to be replaced by gas.

The optimum heat retention temperature of the binder liquid discharge pipe 6 is lower than the boiling point of the binder and is as close to the boiling point as possible. There are various types of binders,
There are various physical properties in terms of temperature, such as solid, liquid, and clear gas, and clear gas but not solid and liquid. However, the thermophysical properties of the binders are common in that they have a boiling point, and at temperatures below the boiling point, the closer they are to the boiling point, the better the fluidity. Therefore, the optimum heat retention temperature is selected.

A heat-retaining heater 19 (spiral sheath electric heater) and a temperature control sensor (not shown) are attached to the outer periphery of the binder gas discharge pipe 7, and
It is covered with a heat insulating material 20 in order to reduce heat radiation loss, and a valve 21 is provided in the middle. The other end 7A of the gas discharge pipe 7 is connected to the combustor 22 in an open manner, and the gas is ignited by the auxiliary pilot burner 23 in the combustor 22 and completely combusted.

A combustion air supply pipe 24 is connected to the combustor 22, and an exhaust gas duct 25 of a fireproof and heat insulating structure for discharging combustion waste gas to the atmosphere is connected to the combustor 22. The optimum heat retention temperature of the gas discharge pipe 7 is a temperature higher than the boiling point of the binder in which the binder vapor does not liquefy in the pipe 7, and the heat retention cost is low, so that liquefaction in the gas discharge pipe 7 is prevented. Therefore, there is no gas-liquid co-firing in the combustor 22 and no soot dust is generated (see FIG. 2).

Since the binder vapor has a higher density than the reducing gas, it is easy to separate the binder vapor into the lower part of the inner space of the semi-firing furnace 1 and the reducing gas into the upper part of the inner space of the furnace 1, so that the powder metallurgical compact Since the quality unevenness is likely to occur, the gas outlet 5 is provided near the bottom 2 of the furnace side wall 4 near the bottom 2 of the furnace so that the reducing gas can reach the lower part of the furnace 1. The concentration distribution of steam and reducing gas can be improved.

In the above embodiment, the binder liquid in the semi-baking furnace 1 gathers smoothly and quickly at the discharge port 3 along the inclined surface of the furnace bottom 2 and is less carburized, and the binder liquid discharge pipe 6 is used to It flows into the liquid recovery container 15. Further, since the discharge pipe 6 is kept at the optimum heat retention temperature, the binder liquid has good fluidity and is smoothly recovered. Nitrogen gas is supplied and replaced in the binder liquid recovery container 15, and the combustible gas evaporated in the binder liquid container 15 is heated in the semi-firing furnace 1 above the discharge pipe 6 from the degassing pipe 11. Be guided to.

Therefore, the combustible gas does not leak from the recovery container 15 and the danger is eliminated. The amount of the combustible gas returned to the semi-firing furnace 1 is the same as the volume of the liquid flowing into the binder liquid recovery container 15, and promotes the inflow of the binder liquid into the recovery container 15. On the other hand, the binder vapor and the reducing gas are introduced into the combustor 22 from the gas discharge pipe 7 that is kept at the optimum heat retention temperature, ignited and burned by the auxiliary combustion pilot burner 23, and the exhaust gas is exhausted from the exhaust gas duct 25 to the atmosphere. Released inside. The gas discharge pipe
Since 7 is kept at the optimum heat retention temperature, the gas guided to the combustor 22 in the exhaust pipe 7 does not liquefy,
Only the gas is completely combusted in the combustor 22 and the gas-liquid co-firing does not occur. Therefore, as shown in FIG. 2, soot (smoke) is not generated and the conventional dust collector is unnecessary.

Further, the temperatures of the both discharge pipes 6 and 7 are detected by a temperature control sensor, and are kept at the set optimum heat retaining temperature by the heat retaining heaters 8 and 19. According to the above-mentioned embodiment of the present invention, since both the discharge pipes 6 and 7 are detachable, the inside of the pipes can be easily cleaned, and the discharge ports 3 and 5 are opened at appropriate positions of the semi-baking furnace 1. Therefore, the liquid and gas of the binder can be reliably separated and discharged, and since the furnace bottom 2 is inclined so as to be lower toward the discharge port 3 of the binder liquid, the liquid of the binder can be vaporized. Without being carburized, the quality of the powder metallurgical molded body can be improved without carburizing, the time for vaporizing the liquid of the binder can be omitted, and the productivity can be improved.

The present invention is not limited to the above-described embodiment, but the gas vent pipe 11 can be omitted by increasing the inner diameter of the binder liquid discharge pipe 6, for example.

[0024]

As described above, the present invention is an apparatus for separating the liquid of the molding binder discharged from the semi-firing furnace of the powder metallurgical molded body and the gas such as steam, and incinerating the gas. A binder liquid discharge pipe is provided at the bottom of the semi-baking furnace,
The other end of the discharge pipe is connected to a binder liquid recovery container, a gas discharge pipe of binder vapor or the like is connected to the lower side wall of the semi-baking furnace, the other end of the gas discharge pipe is connected to a combustor, and both discharge pipes are connected. Since it is characterized in that a valve is installed in the exhaust gas, the binder liquid and gas can be separated, and only the gas can be burned, so it is possible to prevent the generation and adhesion of soot and dust as in gas-liquid co-firing, and the exhaust gas duct. Soot dust does not accumulate inside, preventing dust explosion accidents in the exhaust gas duct and enabling safe and stable operation, solving the problem of regular cleaning of the exhaust gas duct, and eliminating the need for a dust collector. Since electricity can be used and the binder liquid can be stably recovered, there is no accidental burnout of incidental equipment, and environmental disaster prevention and productivity can be improved.

Further, the present invention is characterized in that at least one or both of the binder liquid discharge pipe and the gas discharge pipe is heated and kept warm, so that the fluidity of the binder liquid is improved and the binder liquid is smoothed. And it can be recovered quickly, and it is possible to guide only gas to the combustor without liquefying the vapor of the binder, it is possible to completely prevent gas-liquid co-firing in the combustor, and to generate soot and dust. The safety can be further improved by eliminating all of them.

Furthermore, the present invention is characterized in that the binder liquid recovery container has a closed structure, nitrogen gas is supplied into the container, and the combustible gas in the container is guided to a combustor through a gas vent pipe. Therefore, it is possible to prevent the flammable gas in the binder liquid recovery container from leaking to the outside to improve safety, and to discharge the flammable gas and guide it to the combustor for incineration, which enables safer processing. Is.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a graph showing the concentration of dust in the example of the present invention and the conventional example.

FIG. 3 is a vertical sectional view showing a conventional example.

[Explanation of symbols]

 1 Semi-firing furnace for powder metallurgical compacts 2 Furnace bottom 4 Side wall 6 Binder liquid discharge pipe 7 Gas discharge pipe 8 Heat retention heater 9 Heat insulation material 10 Valve 11 Gas vent pipe 15 Binder liquid recovery container 16 Closed lid 18 Nitrogen gas supply pipe 19 Heat insulation heater 20 Heat insulation material 21 Valve 22 Combustor

Claims (3)

[Claims] 1. A device for separating a liquid of a molding binder discharged from a powder metallurgical compact semi-baking furnace and a gas such as steam and incinerating the gas, wherein the binder liquid is provided at the bottom of the semi-baking furnace. An exhaust pipe is provided, the other end of the exhaust pipe is connected to a binder liquid recovery container, a gas exhaust pipe for binder vapor or the like is connected to the lower part of the side wall of the semi-baking furnace, and the other end of the gas exhaust pipe is connected to a combustor. In addition, a valve is provided on both discharge pipes, and an apparatus for treating discharged gas and liquid in a semi-firing furnace for powder metallurgical compacts is provided. 2. The apparatus for treating exhaust gas / liquid in a semi-firing furnace for powder metallurgical compacts according to claim 1, wherein at least one or both of the binder liquid exhaust pipe and the gas exhaust pipe are heated and kept warm. 3. The binder liquid recovery container has a closed structure, nitrogen gas is supplied into the container, and the combustible gas in the container is led to a semi-firing furnace or a combustor through a gas vent pipe. Item 1. A device for treating discharged gas and liquid in a semi-firing furnace for a powder metallurgical compact according to item 1 or 2.