JP7292833B2 - Spray pyrolysis equipment - Google Patents

Description

The present invention relates to a spray pyrolysis apparatus.

A manufacturing apparatus utilizing a spray pyrolysis method is used as a manufacturing apparatus for hollow fine particles. The internal heating reactor used in this manufacturing method has a reaction section made of ceramics, metal, heat-resistant bricks, or the like. A combustion tube is installed at some part of the reactor, and a gas burner is installed in the combustion tube for producing combustion gases. The combustion tube has a combustion chamber inside. A spray device (nozzle unit) for spraying the aqueous solution is installed. The nozzle used here is called a 2-fluid or 4-fluid nozzle, and an aqueous solution is ejected from the tip at the same time as compressed air to form a mist to form fine particles. These microparticles are dried in the reaction tube and become a product. The product is collected by using a bag filter with a negative pressure inside the core tube using a suction fan. In order to obtain the target specific gravity and particle size, as processing conditions, a certain processing time and processing temperature are required.

In general, compared to external heat atomizers, internal heat atomizers flow into the reactor not only the gas generated by the mist but also the combustion gas generated by the gas burner, so the total gas in the reactor increase in quantity. Therefore, there is a problem that the gas flow velocity in the reaction furnace increases, and the target processing time (residence time in the furnace) of the particles cannot be secured. As a result, particles with insufficient melting and weak strength are produced. This can be solved by increasing the size of the equipment, or by placing multiple gas burners, as in Patent Documents 1 to 3, to generate a swirl flow in the furnace and keep the particles in the furnace for a long time. can. At the same time, it is possible to suppress temperature unevenness in the furnace.

Japanese Patent Application Laid-Open No. 2004-292223 JP 2007-84355 A JP-A-2001-137699

However, the devices of Patent Documents 1 and 2 have a complicated structure, so the equipment cost is high. Moreover, since many gas burners are installed, there is a problem that it is difficult to manage the treatment temperature and treatment time. Moreover, in the apparatus of Patent Document 3, the spray mist comes into contact with the flame, and the solid particles and the hollow particles are mixed, which is not preferable when trying to produce homogeneous hollow particles.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a spray pyrolysis apparatus that does not have a complicated structure, prevents the sprayed mist from coming into direct contact with flames, and allows the mist to be treated for a sufficient amount of time.

Therefore, as a result of various studies to solve the above problems, the present inventors have made a horizontal tube a combustion furnace in which a combustion burner is provided, and provided a vertical reaction tube equipped with a spray device at the tip of the horizontal tube. Instead of aligning the base axes of the connecting parts of the vertical pipes, if the connecting parts are connected with the base axes shifted, the hot air that has moved from the horizontal pipes will generate a swirling flow and move up the vertical pipes. As a result, the inventors found that the mist sprayed from the bottom of the vertical tube rides on the swirling flow and rises up the vertical tube to obtain a sufficient treatment time to produce hollow particles, and completed the present invention.

That is, the present invention provides the following [1] to [5].

[1] A spray pyrolysis reactor having a shape in which a horizontal tube combustion furnace and a vertical tube reactor are connected, and a combustion burner for generating a flame in the vertical tube direction at the end of the horizontal tube, A spray device for spraying the raw material liquid upward is provided at the bottom of the vertical pipe, and the horizontal pipe and the vertical pipe are connected with the base axis shifted so that the hot air flowing from the combustion furnace to the vertical pipe creates a swirling flow at the connection part. A spray pyrolysis apparatus characterized by:
[2] The spray pyrolysis apparatus according to [1], wherein the base axis of the connecting portion of the horizontal tube and the vertical tube has a deviation of 10% or more and 90% or less when the inner diameter of the vertical tube is taken as 100%.
[3] The spray pyrolysis apparatus according to [1] or [2], wherein the spray device is installed at a position where the flame generated from the combustion burner does not come into direct contact.
[4] The spray pyrolysis apparatus according to any one of [1] to [3], wherein the inner diameter of the portion connected to the vertical tube in the combustion furnace is smaller than the inner diameter of the vertical tube.
[5] The spray pyrolysis apparatus according to any one of [1] to [4], which comprises, as an auxiliary heat source, one or more units selected from an auxiliary combustion burner, a hot air heater and an electric heater.

When the spray pyrolysis apparatus of the present invention is used, the spray mist does not come into direct contact with the flame and rises along with the swirling flow generated by the simple apparatus. Homogeneous hollow particles can be produced efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic which shows an example of this invention spray pyrolysis apparatus. FIG. 4 is a schematic cross-sectional view showing an example of misalignment of the base axis of the connecting portion of the horizontal tube and the vertical tube. It is a cross-sectional schematic diagram showing an example of a spray pyrolysis apparatus in which a combustion auxiliary burner is arranged as an auxiliary heat source. The right side shows the BB section. It is a cross-sectional schematic diagram showing an example of a spray pyrolysis apparatus in which a hot air heater is arranged as an auxiliary heat source. The right side shows the AA section. It is a cross-sectional schematic diagram showing an example of a spray pyrolysis apparatus in which an electric heater is arranged as an auxiliary heat source. 1 shows scanning electron microscope images of hollow particles obtained using the apparatus of the present invention.

The spray pyrolysis apparatus of the present invention is of the internal combustion type, in which the combustion furnace is arranged in a horizontal tube and the reactor with the atomizing device is arranged in a vertical tube (Fig. 1). That is, it has a spray pyrolysis reactor in the form of a combustion furnace 1 made up of a horizontal tube and a reactor 2 made up of a vertical tube connected to each other.
The outer walls of the horizontal and vertical tubes are preferably made of a heat-resistant metal such as iron, stainless steel, Inconel, Hastelloy, titanium, and the like. The horizontal pipe and the vertical pipe are substantially cylindrical in shape, because they can be connected by flanges, the temperature unevenness in the cross-sectional direction in the reactor, and the heat dissipation unevenness in the cross-sectional direction from the horizontal pipe and the vertical pipe can be suppressed. is preferred. Also, the horizontal pipe may not be perfectly horizontal, but may be substantially horizontal.

The end of the horizontal tube is equipped with a combustion burner 3 that produces a flame in the direction of the vertical tube (Fig. 1). Both liquid fuel and gaseous fuel can be used as the fuel for the combustion burner. Specifically, gaseous fuels such as LPG, city gas, and vaporized organic matter, and liquid fuels such as kerosene, light oil, heavy oil, and recycled oil can be used.
The length of the horizontal pipe is preferably such that the flame generated from the combustion burner does not come into direct contact with the atomized mist. However, if the distance between the flame generated from the combustion burner and the spray mist is too long, the thermal efficiency will be insufficient.

At the bottom of the vertical tube, a spray device 4 for spraying the raw material liquid upward is provided (Fig. 1). The spray device 4 has a spray nozzle at its tip.
The spray nozzle is positioned to spray upwards at the bottom of the vertical tube (Fig. 1). The number of spray nozzles may be one or two or more. The spray nozzle is preferably a 2- to 4-fluid nozzle, and using compressed air as carrier air, the spray nozzle is doubled so that an air shield is formed around the spray mist, and the solution is sprayed. You can spray it. Also, the spray nozzle may be protected by a heat insulating material or the like as necessary in consideration of heat resistance.
The atomizer is preferably installed at a position where it is not in direct contact with the flame generated by the combustion burner.

The horizontal tube and the vertical tube in the spray pyrolysis apparatus of the present invention are characterized in that they are connected with their base axes shifted so that the hot air flowing from the combustion furnace (horizontal tube) to the vertical tube generates a swirling flow at the connecting portion. . Here, shifting the base axis means that the central axis of the connecting portion of the horizontal tube and the vertical tube is shifted, as shown in FIGS. 1 and 2, for example. Since the base axis (central axis) is misaligned in this way, when the hot air generated in the horizontal pipe passes through the vertical pipe, it does not rise straight up, but rises with a swirling flow. The mist sprayed on the vertical tube rides on this swirling flow and ascends the vertical tube (reaction furnace), ensuring a sufficient reaction time (processing time).

The misalignment of the base axis (central axis) (Figs. 1 and 2) affects the degree of swirl flow generation, thermal efficiency, and the heat resistance of the horizontal pipe due to heat buildup in the horizontal pipe. As 100%, 10% or more and 90% or less is preferable, and 20% or more and 80% or less is more preferable. Further, as far as the deviation of the base axis (central axis) is generated, it may be lateral or oblique with respect to the horizontal tube direction, but the oblique direction is preferable.

It is preferable that the internal diameter of the portion of the combustion furnace (horizontal pipe) connected to the vertical pipe be smaller than the internal diameter of the vertical pipe, since a strong swirling flow of hot air is likely to occur (see FIG. 2). More preferably, the inner diameter of the connecting portion of the horizontal pipe is half or less than the inner diameter of the vertical pipe.

Also, one or more auxiliary heat sources may be arranged above the spray nozzle. The auxiliary heat source includes one or more selected from auxiliary combustion burners (Fig. 3), hot air heaters (Fig. 4) and electric heaters (Fig. 5). The auxiliary heat source may be installed at any position above the spray nozzle, and the number of auxiliary heat sources may be one, but two to six may be arranged depending on the length of the pyrolysis furnace. In the case of electric heaters, they may be provided around the inside of the furnace.
By installing an auxiliary heat source, it is possible to provide heat equivalent to the amount of heat dissipated from the furnace body, and to stably secure the temperature and holding time necessary for synthesizing hollow particles with good reproducibility.
In addition, when using a combustion auxiliary burner or a hot air heater as an auxiliary heat source, by arranging it in the same swirling direction as the swirling flow generated in the horizontal pipe and rising from the vertical pipe in the tangential direction in the furnace body, the generated This is preferable because the swirl flow of the combustion gas is not hindered and the swirl flow can be supplemented by the combustion gas generated from the auxiliary heat source (Figs. 3 and 4).
The combustion auxiliary burner and the hot air heater may be installed on different surfaces and heights in order to adjust the furnace temperature and swirling flow. The surfaces to be installed may be arranged in the vertical direction of the pyrolysis furnace or facing each other as shown in FIGS. The installation height may be the same height (on the same circumference) or different levels.

In addition, the flame of the auxiliary combustion burner, which is the auxiliary heat source, should not come into direct contact with the spray mist and the hollow particles that are generated. preferable. It is preferable to install the flame of the auxiliary combustion burner so that the flame of the auxiliary combustion burner does not directly contact the atomized mist or the hollow particles produced so that the flame of the auxiliary combustion burner does not enter the furnace. In order to prevent the flame of the auxiliary combustion burner from entering the furnace, a mechanism for moving the auxiliary combustion burner back and forth may be provided and adjusted according to the length of the flame.

A bag filter for collecting the produced hollow particles can be installed in the upper part of the spray pyrolysis apparatus of the present invention. A cyclone may be placed before the bag filter to reduce the load on the bag filter and collect coarse particles and foreign matter.In addition, if a heat exchanger is placed, residual heat can be used and the amount of exhaust gas can be reduced. Therefore, it is preferable. Further, dust removal and purification equipment such as a scrubber may be arranged after the bag filter, if necessary.

When the spray pyrolysis apparatus of the present invention is used, the spray mist rides on the swirling flow and reacts in the reaction furnace for a long period of time, so that fine hollow particles can be obtained stably and efficiently. In the case of spray pyrolysis using a raw material liquid as a raw material of an inorganic oxide, if the raw material droplets do not come into direct contact with a flame, the drying reaction proceeds first and the mist becomes hollow particles. Subsequently, if the thermal decomposition reaction proceeds, inorganic oxide hollow fine particles are obtained. Here, examples of inorganic oxides include metal oxides, alumina, silica, calcia, magnesia, oxides composed of aluminum and silicon, and more specifically oxides composed of alumina, silica, aluminum and silicon. oxides, titanium oxides, magnesium oxides, calcium oxides, sodium oxides, potassium oxides, lithium oxides, boron oxides, phosphorous oxides, zirconium oxides, barium oxides, cerium oxides, yttrium oxides, etc. and composite oxides in which these oxides are combined.
Solvents for dissolving or dispersing the raw materials of the elements constituting these oxides include water and organic solvents, but water is preferable from the viewpoint of environmental impact and production costs. or alkali may be added. Examples of acids that can be used include hydrochloric acid, nitric acid, sulfuric acid, and organic acids. Examples of alkalis that can be used include sodium hydroxide, calcium hydroxide, potassium hydroxide, and the like.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1
As shown in FIGS. 1 and 2, a reaction tube having a shape combining a horizontal tube (inside diameter of the connecting portion with the vertical tube: 145 mm) and a vertical tube (inside diameter: 200 mm) was installed. The axis of the horizontal tube was shifted by 50 mm from the vertical tube with an inner diameter of 200 mm, and the deviation of the axis of the joint between the horizontal tube and the vertical tube was set to 25%. A gas burner was installed in the horizontal tube and the atomizing device (nozzle) was installed in the lower part of the vertical tube (see Figure 1).
Then, a mixed aqueous solution of aluminum and silicon in which 0.04 mol of aluminum nitrate and 0.16 mol of tetraethyl orthosilicate were dissolved in 1 liter of distilled water was put into the solution tank. The supplied aqueous solution was sprayed in a mist state through a two-fluid nozzle by a liquid-sending pump, and passed through a reaction section (internal temperature: 1000°C). Hollow particles were then recovered using a bag filter.
A scanning electron microscope image of the resulting hollow particles is shown in FIG. According to the present invention, temperature unevenness was improved and a sufficient residence time was ensured, so hollow particles were obtained which melted homogeneously and had high strength.

1: Horizontal pipe (combustion furnace)
2: vertical tube (reactor)
3: Combustion burner 4: Atomization device

Claims (3)

a spray pyrolysis reactor having a shape in which a horizontal tube combustion furnace and a vertical tube reactor are connected;
a combustion burner that produces a flame in the vertical tube direction at the end of the horizontal tube;
Equipped with a spray device that sprays the raw material liquid upward at the bottom of the vertical pipe,
The outlet of the atomizer is installed at a position higher than the center of the flame generated from the combustion burner,
The horizontal pipe is connected to the bottom of the vertical pipe with the base axis shifted so that the hot air flowing from the combustion furnace to the vertical pipe generates a swirling flow at the connecting part , and the displacement of the base axis is 10% or more and 90% when the vertical pipe inner diameter is 100%. % or less . 2. The internal combustion spray pyrolysis apparatus for producing hollow particles according to claim 1 , wherein the inner diameter of the portion connected to the vertical tube in the combustion furnace is smaller than the inner diameter of the vertical tube. 3. The internal combustion spray pyrolysis apparatus for producing hollow particles according to claim 1 or 2, comprising at least one unit selected from an auxiliary combustion burner, a hot air heater and an electric heater as an auxiliary heat source.

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