JPS6358089A - Method of operating fluidized bed furnace - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to compressing a sand-like heating medium such as alumina powder, zircon sand, etc., which is filled in a furnace and heated by a heater, and which is supplied from the bottom of the furnace. It relates to a method of operating a fluidized bed furnace that heats plastic molding molds, etc. by fluidizing gas, and in particular, starts the operation of the fluidized bed furnace and heats the inside of the furnace from room temperature to a predetermined temperature. This article relates to an operating method when the temperature rises.

[Prior art and its problems]

In a fluidized bed furnace, a sand-like heating medium filled in the furnace is fluidly stirred with compressed gas supplied from the bottom of the furnace, and then heated to approximately 300 to 350°C with a heater. A plastic molding mold is placed on top of the furnace and heated for a certain period of time, and the plastic molding mold heated in the fluidized bed furnace is transferred to another process and the mold is removed from the plastic molding material supply device. It is designed to heat and melt the plastic molding material filled and supplied into the mold.

By the way, when the temperature of a fluidized bed furnace starts to rise, each particle of the heating medium filled in the furnace has a heavy specific gravity at room temperature, and the very fine particles are densely packed together and have no fluidity. It is in a state.

Therefore, the air permeability between each particle of the heating medium is poor, and the flowability of the compressed gas supplied from the bottom of the furnace is poor, so the heat of the heater that heats the heating medium is difficult to be released into molecules, and the amount of heat dissipated by the heater is large. In such a case, the surrounding area may reach an abnormally high temperature, which may cause the heater to burn out.

In addition, each particle of the heating medium that has been sufficiently heated by the heater increases its fluidity and its specific gravity becomes extremely light, so its movement becomes active and it becomes like a boiling liquid, causing the furnace to melt. If the output of the compressed gas supplied from the bottom is too high, there is a risk that it will overflow outside the furnace.

Additionally, if the output of the compressed gas is so high that the heating medium overflows outside the furnace, a large amount of the heat inside the furnace will escape to the outside of the furnace together with the compressed gas, resulting in large heat loss and extremely low heating efficiency. It gets worse.

For this reason, in the past, the output of the compressed gas supplied from the bottom of the furnace was kept low from the beginning to the extent that particles of the heating medium with a reduced specific gravity would not blow out of the furnace and could be heated efficiently without heat loss. At the same time, the heat dissipation amount of the heater is also set to be low enough to prevent burnout of the heater at the start of temperature increase when the heating medium is solidified.

However, according to such conventional methods, for example, when starting the operation of a fluidized bed furnace for manufacturing relatively large automobile parts, it takes a very long time to raise the temperature, usually about 7 to 8 hours, and the work efficiency is extremely low. At the same time, there was a serious drawback in that running costs such as electricity costs increased significantly.

[Purpose of the invention]

Therefore, the present invention prevents the heater installed in the furnace from burning out and the heating medium overflowing outside the furnace when the fluidized bed furnace starts operating and raises the temperature inside the furnace to a predetermined temperature. It is an object of the present invention to provide a method for operating a fluidized bed furnace that can efficiently raise the temperature inside the furnace in a short time without causing heat loss and with very little heat loss.

[Structure of the invention]

In order to achieve this object, the present invention has been developed by making a sand-like heating medium filled in a furnace and heated by a heater flowed by compressed gas supplied from the bottom of the furnace, and placing gold on top of the heating medium. In a method of operating a fluidized bed furnace configured to heat a mold,
When the temperature in the furnace starts to rise, the compressed gas is supplied at the required high power to forcibly disperse the heat of the heater into the heating medium that is solidified at room temperature, and after the solidified heating medium is loosened, the compressed gas is It is characterized by raising the temperature inside the furnace to a predetermined temperature while decreasing the output of compressed gas in stages according to the rise in temperature inside the furnace.

[Action of the invention]

According to the method of the present invention, at the start of temperature rise, compressed gas is supplied at the required high output that can forcefully disperse the heat of the heater into the heating medium that is solidified at room temperature, so the amount of heat dissipated from the heater is Even if the temperature is increased compared to conventional methods, there is no risk of overheating the surrounding area and causing burnout of the heater. Therefore, by increasing both the amount of heat dissipated by the heater and the amount of compressed gas supplied, the solidified heat medium can be heated in an extremely short time. It can be loosened and fluidized.

In addition, after the solidified heating medium is loosened, the output of the compressed gas is gradually reduced according to the temperature rise inside the furnace, so that the heating medium whose specific gravity becomes lighter as the temperature inside the furnace rises is released outside the furnace. It is possible to prevent overflow, suppress heat loss due to heat dissipation to the outside of the furnace, and efficiently raise the temperature inside the furnace in a short time.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 is a flow sheet diagram showing a schematic configuration of a fluidized bed furnace using the method of the present invention, and FIG. 2 is a graph for explaining the method of the present invention.

In the figure, reference numeral 1 denotes a fluidized bed furnace, in which a furnace body 2 made of an insulated wall is filled with a fine sand-like heat medium 3 such as zircon sand, and a sheathed heater etc. that heats the heat medium 3. A heater 4 is provided.

Further, an air supply chamber 5 to which compressed air (compressed gas) is supplied is provided at the bottom of the furnace body 2, and a dispersion plate 6 is provided on the top surface of this air supply chamber 5 to blow out compressed air into the furnace. The heat of the heater 4 is uniformly distributed in the furnace by the compressed air blown upward from the distribution plate 6, and the heating medium 3 filled in the furnace is made to flow. has been done.

Reference numeral 7 denotes an air supply pipe connected between the air supply chamber 5 and a compressed air supply source (not shown), and a flow meter 8 and a flow rate adjustment valve 9 are interposed in the air supply pipe 7. ing.

Reference numeral 10 indicates a temperature detection signal from a temperature detector 11 provided in the furnace body 2, a flow M detection signal from the flow meter 8, etc., from a dispersion plate 6 disposed at the bottom of the furnace body 2. A control signal for varying the output of compressed air to be ejected is sent to the flow rate adjustment valve 9.
This is a wholesale edition that is output for.

12 is a mold for plastic molding placed on the heat medium 3 filled in the furnace body 2, and after being heated in the furnace body 2 for a certain period of time, it is transferred to another process and the plastic molding material is A feeding device (not shown) is adapted to fill the plastic molding material along its inner wall.

Note that 3 is a filter that collects dust, etc. in the compressed air supplied from the compressed air supply source, and 14 is a filter that collects the compressed air at a rate of, for example, 4 to 5 kg/cm from the compressed air supply source. This is a pressure reducing valve that reduces the pressure to about 2.5 kg/cnl.

The above is an example of the configuration of a fluidized bed furnace using the method of the present invention. Next, the method of the present invention using this will be explained with reference to FIG. 2.

When the fluidized bed furnace 1 starts operating and the temperature starts to rise, at the same time as the heater 4 starts heating, the output of the compressed air blown out from the dispersion Fi 6 provided at the bottom of the furnace body 2 becomes solid at room temperature. The flow rate regulating valve 9 is adjusted so that the required high output is obtained to forcefully disperse the heat of the heater 4 into a certain heating medium 3.
The opening degree of the opening is set by a control signal from the control panel 10.

Here, as shown in FIG. 2, the output of the compressed air ejected from the dispersion plate 6 is 2.5 kg/c
n! The air output is selected to be equivalent to, for example, about 60% of the air output when compressed air supplied at a pressure of

In this way, when the compressed air is ejected from the distribution plate 6 at a high output of about 60%, the heat of the heater 4 is forcibly dispersed into the heat medium 3 without being accumulated around the heater 4. The heater 4 will not be overheated and burn out the hot wire, etc., and the amount of hot air that can permeate into the solidified heat medium 3 will be large, resulting in very good heat conduction efficiency to the heat medium particles. Therefore, the entire heat medium 3 is easily loosened in a short time.

Note that at this time, the inside of the furnace body 2 is at a relatively low temperature of 100° C. or less, so even if compressed air is supplied at high output, the amount of heat escaping to the outside of the furnace is small, and heat loss is extremely small.

Then, when the temperature inside the furnace body 2 gradually rises and the solidified heating medium 3 completely loosens and increases its fluidity, for example reaching 100°C, based on the detection signal from the temperature detector 11 that has detected the temperature. In order to prevent each particle of the heating medium 3, which has been heated and has a lighter specific gravity and improved fluidity, from blowing out of the furnace together with the compressed air, the air output from the control panel 10 to the flow rate adjustment valve 9 is reduced by approximately 55%. A control signal is output to lower the temperature to .

Note that when the heating medium 3 loosens and increases its fluidity, the air permeability between the particles of the heating medium 3 also improves, making it easier for the compressed air supplied from the bottom of the furnace to come out of the furnace body 2. By reducing the output of compressed air from 60% to 55% and reducing the wind speed of the compressed air supplied into the furnace body 2, the amount of heat that escapes to the outside of the furnace together with the compressed air is reduced, reducing heat loss. It can be suppressed.

When the temperature inside the furnace body 2 reaches 200°C and the specific gravity of each particle of the heating medium 3 becomes even lighter, the output of the compressed air is reduced to about 4
By reducing the amount to 5%, the heating medium 3 is prevented from overflowing, and at the same time, heat loss in the furnace body 2 is also suppressed.

When the temperature inside the furnace body 2 rises to about 300 degrees Celsius and the temperature rise is completed, the output of compressed air is reduced to about 35% of the optimum level during normal operation, and the heating temperature of the heater 4 is also increased. 300 to 350℃ required for normal operation inside 2
The temperature is set so that it can be maintained at a predetermined temperature.

Note that even if the output of compressed air is reduced to about 35% in this way, the heating medium 3 will be heated to a high temperature as the temperature inside the furnace body 2 increases, and its specific gravity will become extremely light and its fluidity will become extremely low. The heat dissipation of the heater 4 is also very good, and the heater 4
No burnout accidents occur due to overheating. Furthermore, since the output of the compressed air is low, there is less heat dissipation from the high-temperature inside of the furnace to the outside of the furnace.

As described above, the output of the compressed air supplied at the start of operation of the fluidized bed furnace 1 is gradually increased from the high output of about 60% set at the start of temperature rise every time the temperature inside the furnace rises by 100°C. It has been confirmed through experiments that when the temperature is reduced to 55% to 35%, the time required to raise the temperature inside the furnace is about 2 to 3 hours, which is about 2 hours compared to the conventional method.

Therefore, there are excellent effects in that work efficiency is significantly improved and running costs such as electricity costs are significantly reduced compared to the conventional method.

When the inside of the furnace main body 2 reaches the required heating temperature as described above, the plastic molding mold 12 is placed on the heating medium 3 from above, and the mold 12 is brought into contact with the lower surface side of the heating medium 3. The plastic molding material is heated for a certain period of time by the flowing heating medium 3, and then transferred to another step, where the plastic molding material is filled into the mold 12 and heated and melted.

〔Effect of the invention〕

As described above, according to the present invention, when starting the operation of a fluidized bed furnace and raising the temperature inside the furnace, the compressed gas supplied from the bottom of the furnace is initially a heat medium that is solidified at room temperature. Since the heat is supplied at the required high power that can forcefully disperse the heat of the heater, even if the amount of heat radiated by the heater is increased, there is no risk of overheating the surrounding area and causing a burnout accident of the heater.
It is possible to loosen and fluidize a solidified heat medium in an extremely short time. In addition, after the heating medium is loosened, the output of the compressed gas is reduced in stages according to the temperature rise in the furnace.
This prevents the heating medium, whose specific gravity decreases as the temperature rises inside the furnace, from overflowing outside the furnace, and also suppresses heat loss due to heat dissipation outside the furnace, raising the temperature inside the furnace efficiently and in a short time. can do.

Therefore, there is an excellent effect that working efficiency can be significantly improved and running costs such as electric power costs can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet diagram showing a schematic configuration of a fluidized bed furnace using the method of the present invention, and FIG. 2 is a graph for explaining the method of the present invention. Explanation of symbols 1--fluidized bed furnace, 2--furnace body, 3--heating medium, 4--
-Heater, 5--Air supply chamber, 6--Dispersion plate, 7-Air piping, 9--Flow rate adjustment valve, l〇-Control panel, 11--Temperature sensor 12--For plastic molding Mold. Patent Applicant: Trinity Industries Co., Ltd. Figure 2 (Construction Benefits %)

Claims (1)

[Claims] A fluidized bed furnace configured to heat a mold placed on the heating medium by fluidizing a sand-like heating medium filled in the furnace and heated by a heater using compressed gas supplied from the bottom of the furnace. In this operating method, when the temperature in the furnace starts to rise, the compressed gas is supplied at a required high power to forcibly disperse the heat of the heater into the heating medium that is solidified at room temperature, and the compressed gas is 1. A method of operating a fluidized bed furnace, which comprises raising the temperature of the inside of the furnace to a predetermined temperature while gradually lowering the output of the compressed gas after the compressed gas is loosened in accordance with the rise in temperature inside the furnace.