JPS5912745A - Calcining method and furnace - Google Patents

Abstract

PURPOSE:To enable uniform calcination by a small amount of gaseous fuel, in a shaft type furnace of which the inner diameter becomes larger toward the lower part from the upper part thereof, by providing a preheating drying part, a mixed gas injecting part, a gas combustion part, a calcining part, a cooling part and a cooling air injecting part from the upper part of said furnace. CONSTITUTION:By using a shaft type furnace 1 of which the inner diameter becomes larger toward the lower part from the upper part thereof, a flame and a combustion gas from gas burners 8, 8' are flowed toward a negative pressure part position 6 to carry out the calcination of a material in the region from a position 5 to the position 6. In addition, a cooling air stream due to cooling air jet orifices 11, 11' at a position 7 is flowed toward the position 6 to carry out the cooling of the calcined material between the positions 6, 7. Moreover, the negative pressure part position 6 is formed by sucking the combustion gas and air by suction pipes 14, 14' and the mixed gas of the combustion gas and air is injected from injection pipes 9, 9'. On the other hand, a negative pressure part is formed by sucking a gas by discharge pipes 21, 21' and the drying and the preheating of the material supplied from the supply means 2 provided to the top part of the furnace is carried out while the calcined product is taken out by the taking out means 26 provided to the furnace bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to, for example, a method for firing magnetic iron oxide or lime, and a firing furnace.

The firing furnace used in the present invention is a truncated cone-shaped vertical furnace in which the inner diameter of the furnace gradually increases from the top to the bottom. For example, while the height of an incinerator is about 8 m, the inner wall of the furnace is approximately 80 cm at the top and 160 cm at the bottom, and the diameter is tapered downward by approximately IOctn for every meter of height of the furnace. ing. By providing a taper in this way, the grains do not form a bridge in the furnace, and the grains descend under their own weight in the firing furnace, and the fired products are continuously taken out by a take-out means, such as a screw conveyor, installed at the bottom of the furnace. By taking it out, raw raw sashimi to be fired can be fed from the feeding means at the top of the furnace in a natural fall feeding method using gravity. In order to make the lowering of the air inside the kiln smooth, gas blowing sections are provided at three locations, and gas suction sections, ie, negative pressure sections, are provided at two locations.

That is, several gas burners are installed on the peripheral wall of the approximately 4 m high furnace wall of the above-mentioned approximately 8 m high kiln furnace, and flames are blown thereinto. Several suction pipes are installed at a height of approximately 2 m in the furnace to suck in the combustion gas in the furnace, and this position is
Maintain the area at a negative pressure level. The flame and combustion gas create a high-temperature atmosphere of 1200"'C in the 4- to 2-meter-high furnace inside the furnace, and the powder is lowered together with the flame and combustion gas, allowing smooth firing. The bottom of the furnace Cooling air is blown in at a position near the bottom to cool the fired product, and then taken out by the take-out means.The cooling air blown in from near the bottom is collected together with the combustion gas by the suction pipe installed at a height of about 2 m. The mixed gas of the combustion gas and air is blown into the ladle furnace at a height of about 6 m, and the mixed gas is treated at a low temperature near the top of the furnace and exhausted. The 4-1 system, which is supplied from above, is dried and preheated before firing, so that the pre-dried material is uniformly fired as it descends through the firing zone.

The calcining furnace for magnetic acid monoarenite according to the present invention will be explained with reference to FIG. 1 showing an embodiment thereof.

The height of this calcining furnace is approximately 8 m, and the inner diameter of the top is approximately 8 m.
0cm, 1 = The shape is a truncated circle t11 with an inner diameter of 160cm, and its inner circumferential wall should be sufficiently protected with fireproofing and heat insulation. A feeding stage 2 of granulated magnetic iron oxide is provided at the top of the furnace. The supply stage is composed of two stages, such as a hopper and a supply pipe, and if the profit in the furnace falls downward, it will naturally fall from above due to its own weight, and it is a supply system in which replenishment is carried out one by one.

Several gas burners 8, 8', . . . are installed on the peripheral wall of the furnace 1 at a position 5 at approximately the middle height of the furnace 1, that is, at a height of about 4 m. These gas burners 8 each have a gas fuel supply pipe 10 and a wind box 9, and their ejection ends have a heat-resistant structure.

Position 5 is maintained at a positive pressure of about 5 mm of water column and gas burner 8,
The fuel and nitrogen that are vigorously ejected from 8'... reach the center of the furnace and create flames.

Several suction pipes 14, 14', . . . are installed on the peripheral wall of the furnace 1 at a height position 6 of about 2 m, the suction ends of which have a heat-resistant structure. These suction tubes are put together by an annular tube 15, and the annular tube 15 is connected to a suction tube. It is connected to a pipe of a blower 17 having a regulating valve 16. The control valve 16 is adjusted to adjust the position 6 in the furnace to about 100 ml of water column]. A negative pressure of O mIn can be maintained.

Since position 6 in the furnace is under negative pressure of about 10 mrv of water, most of the flame and high temperature combustion gases blown into position 5 in the furnace flow downward.

The high-temperature combustion gas flows parallel to the descending calcined gas,
For example, JI of I 200 'C between position 5 and position 6! The calcination reaction is carried out by keeping the temperature at i. Between position 5 and position 6 is the firing zone.

Provide several cooling air vents 11, 11', . . . in the furnace peripheral wall at position 7 near the bottom of the furnace 1. These cooling air jet holes 11 are connected to an annular pipe 12, and the annular pipe 12 is connected to a cooling air supply pipe having a control valve 13. Therefore, an appropriate amount of cooling air is blown into the furnace at the bottom position 7, flows upward, exchanges heat with the fired product, becomes high-temperature air, and is then taken out of the furnace together with the combustion gas by the suction pipe 14 at position 6. reactor. The area between position 6 and position 70 is a zero zone.

Several ejection pipes 19 are installed around the furnace at a height of about 6 m at position 4 of the furnace 1.
．． 19'... is provided. these? The ejection pipe 19 is connected to the annular pipe 10, and the annular pipe'
10. Connected to the delivery pipe 18 of the blower 17 mentioned above. Therefore, a mixed gas, which is a mixture of high temperature combustion gas and high temperature air, is ejected from the ejection pipe 19.
The position 4 is maintained at a positive pressure of about 10 columns of water, and a considerable amount of mixed gas at a relatively high temperature is vigorously jetted into this position 4 by the jet pipe 19.

Several discharge pipes 21, 21' are installed on the furnace peripheral wall at a position near the top of the furnace 1, that is, at a height position 3 of approximately 8 m in the furnace 1.
will be established. These discharge pipes 21 are combined into an annular pipe 22, which is connected to a suction pipe of a blower 24 having a regulating valve 23. The control valve 23 can be adjusted to maintain position 3 in the furnace at a negative pressure of about 20 wrl of water, position 3 in the furnace at a negative pressure of about 201 M1 of water, and position 4 at a negative pressure of about 20 wrl of water. Because of the positive pressure of IOwrl, the mixed gas injected at position 4 rises actively through the phase separation layer, and by the time it reaches position 3 in the furnace, it has exchanged heat with the raw material and has reached a reliably low temperature. be discharged through the discharge pipe 21.

The material is sufficiently dried and preheated from position 3 to position 4. The area between positions 3 and 4 is a drying zone, and the area between positions 4 and 5 is a preheating zone.

Provide product removal means 26 at the bottom of the furnace 1. The take-out means 26 may be, for example, a screw conveyor, and can continuously take out the pre-fired magnetic iron oxide which has already been fired and cooled to a fairly low temperature by cooling air. In addition, by this extraction, the raw material is lowered into the furnace and the raw material is supplied by its own weight from the supply means 2 at the top of the furnace, and the automatic supply and automatic fall of the raw material from the furnace 1 are as described above. Because it has a moderate taper, it is strong;
Since the inside of the furnace is filled with three suction points and two suction points, smooth descent is performed without creating a bridge, and the desired firing can be performed. The injection of flame by the burner 8 and the injection of the mixed gas by the ejection pipe 19 cause the in-furnace pressure at positions 5 and 4 to be ejected vigorously to a water column of JOmm and a water column of 5 ntm, respectively. When you reach the center, the point will come.

Figure 2 shows the pressure at each position in the furnace and the flow of air in the furnace in the calcining furnace for magnetic iron oxide shown in Figure 1, and Figure 3 shows the inside of the calcining furnace for magnetic iron oxide in Figure 1. shows the altitude distribution of The graph in Figure 3 shows the temperature of each height inside the pre-calcination furnace, with the height of the furnace on the vertical axis and the temperature inside the furnace on the horizontal axis. In this graph, the area from position 3 to position 4 is the drying zone, the area from position 4 to position It5 is the preheating/heating zone, and the area from position 5 to position 6 is the firing reaction zone. Furnace and Sl of the invention: In the forming method, the Q'i firing temperature is approximately 120 in this zone.
A constant temperature of 0° C. is maintained so that the calcination reaction takes place completely. The area between position 6 and position 7 is a cooling zone.

In the firing method and firing furnace of the present invention, firing can be performed with a relatively small amount of gas combustion, and thermal energy can be used effectively, resulting in significant savings in fuel costs. Further, the speed of β1fF in the furnace can be easily adjusted by adjusting the speed of the extraction means. The vortex and pressure at each height in the furnace can be easily adjusted by means of control valves.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a temporary firing furnace for magnetic iron oxide according to the present invention. Figure 2 shows the pressure inside the furnace and the flow of gas in the furnace shown in Figure 1, and Figure 3 shows the temperature distribution inside the furnace, which is not shown in Figure 1. It is a graph. 1 is a calcining furnace for magnetic iron oxide, 2 is a supply means, 3 is an exhaust gas extraction position near the top of the furnace, 4 is a blowing position for a mixed gas of combustion residue and air, 5 is a frog position of a gas burner, and 6 is a suction pipe Several units, 7 is the cooling air blowing position, 8 is the burner, 9 Gi
Wind box, 10 is a gas fuel supply pipe, 11 is a cooling air outlet, 12 is an annular pipe, 13 is a control valve, 14 is a suction pipe, 15 is an annular pipe, 16 is a control valve, 17 is a blower, 18 is a delivery A pipe, 19 is a mixed gas ejection pipe, 20 is an annular pipe, 21 is a discharge pipe, 22 is an annular pipe, 23 is a control valve, 24 is a blower, 25
2 is a delivery tube, and 26 is a take-out means. Agent: Yoshihiko Okoshi 14) Ran 4 Figure 7 (Continued from page 1) Inventor Nobumasa Tagara Honjo-type Kojima 1-10-12 0 Inventor Takata Tamura 1-44 Shimizu-cho, Koda-shi Inventor Mitsumasa Shimazaki 357 Shinobu, Gyoda City Inventor Hitoshi Nagai 5-18-38 Kamakura Kata Omachi 0 Inventor Masao Yomoto 838 Isogo-cho, Isogo-ku, Yokohama ■Applicant Tone Sangyo Co., Ltd. Shimonaka, Gyoda City Article 1612 (Applicant: Takenaka Corporation 4-27 Honmachi, Higashi-ku, Osaka City

Claims (1)

[Claims] (B) A vertical furnace 1 is used, in which the inner diameter of the furnace increases from the top to the bottom, and several gas burners 8.8' and 8.8' The flame and the combustion gas are flowed downward toward the negative pressure section position 6 so that the firing of the grill can be carried out between the position 5 and the position 6. The cooling air flow from the several cooling air jet holes 11, 11'... is caused to flow in the direction of the negative pressure part position 6 above, and the cooling of the fired air is carried out between the position 6 and the position 7. Several suction pipes 14.1 are placed on the furnace wall at position 6 between positions 5 and 7.
4'... is provided to suck the combustion gas and air to create a negative pressure part position 6, and the mixed gas of combustion gas and air sucked by these suction pipes is transferred to position 5 and position 3 near the top. Several mixed gas ejection pipes 19 provided on the furnace peripheral wall at the intermediate height position 4.
19'..., several exhaust pipes 21, 21'... are installed on the furnace wall at position jft 3 to suck the gas and create a negative pressure area near position 4. Drying and preheating are carried out by the monthly σ supplied from the top, and by taking out the fired product by the take-out means 26 provided at the bottom of the furnace, the phase is successively replenished by its own weight from the supply means 2 provided at the top of the furnace. A method of firing. (21) A vertical furnace 1 is provided, the inner diameter of which is narrower from the L part to the lower part, and a supply means 2 for the mixture to be fired is provided at the top of the furnace 1, and a middle height position of the furnace 1 is provided. 5 Several gas burners 8,8'... are installed on the peripheral wall of the furnace 1, and several cooling air jet holes 11,11 are installed on the peripheral wall of the furnace at position 7 near the bottom of the furnace 1.
'... are provided on the furnace peripheral wall at an intermediate height between positions 5 and 7, and several suction pipes 14.14 are provided to suck in combustion gas and air.
..., and several mixed gas jetting pipes 19, 19 are installed on the furnace peripheral wall at a mid-height position 4 between position 5 and position 3 near the top of the furnace.
'... were provided, several discharge pipes 21, 21',... were provided on the furnace peripheral wall at position 3 near the top of the furnace 1, and a fired product removal means 26 was provided at the bottom of the furnace 1. Firing furnace.