WO2012060157A1

WO2012060157A1 - Vertical kiln

Info

Publication number: WO2012060157A1
Application number: PCT/JP2011/070906
Authority: WO
Inventors: 博増田; 功藤井; 勝幸近藤
Original assignee: 宇部興産機械株式会社
Priority date: 2010-11-01
Filing date: 2011-09-13
Publication date: 2012-05-10
Also published as: CN103189703B; KR20130140734A; JP2012097943A; JP5636881B2; KR101789642B1; CN103189703A

Abstract

This vertical kiln (1) is provided with an outer tube (2) and an inner tube (3), and is provided with a starting material pathway (20) therebetween. A fired article discharge mechanism that discharges fired articles from the kiln is provided to the bottom end of the outer tube (2), below which a fired article cooling mechanism that cools the fired articles by introducing cooling air is provided. The fired article cooling mechanism is configured from a fired article introduction tube (22) and a fired article cooling device (21), and a fired article packed bed (23) following on from a fired article packed bed (21b) is formed in the fired article introduction tube (22). Most of the cooling air introduced to the fired article cooling device (21) does not flow upwards from the fired article packing layer (23), instead passing through a duct (30) connected to an upper space section, (21c) and being used as combustion air in a lower combustion chamber (17).

Description

Vertical firing furnace

This invention relates to a vertical firing furnace for firing massive raw materials such as limestone and dolomite.

Conventionally, a double-cylindrical vertical firing furnace for firing bulk materials such as limestone and dolomite is known (for example, see Patent Document 1 below). FIG. 4 is a view showing a conventional vertical firing furnace having a double cylindrical structure. As shown in FIG. 4, the vertical firing furnace 100 includes a cylindrical outer cylinder 101 and an inner cylinder 102 disposed concentrically on the inner side.

A feeding device 103 for supplying raw material supplied from the transfer device is provided at the upper end of the outer cylinder 101, and the upper end of the outer cylinder 101 is connected to an exhaust gas suction fan (not shown) via a pipe 104. Is done. And the exhaust gas from the outer cylinder 101 is discharged | emitted in air | atmosphere through the dust collector which is not shown in figure.

In the inner cylinder 102, a cooling air passage 105 for the inner cylinder 102 is formed, and cooling air is supplied to the passage 105 from a fan 107 via a pipe 106. The air cooled in the inner cylinder 102 is collected in the pipe 108a and used as combustion air. The upper end portion of the inner cylinder 102 is connected to the upper end portion of the operating air heat exchanger 110 via a pipe 109, and the lower end portion of the operating air heat exchanger 110 is connected to the exhaust gas suction fan via the pipe 111. Connected to.

Outside the operating air heat exchanger 110, outside air is introduced from the blower 112, and heat is exchanged with the exhaust gas in the operating air heat exchanger 110. The outside air heated by this heat exchange is supplied to the upper burner 114a of the upper combustion chamber 114, the lower burner 115a of the lower combustion chamber 115, and the upper end of the suction device 116, which are provided in the outer cylinder 101 via the pipe 113. Used as combustion air and air for operating the suction device 116.

The cooled air that has cooled the inner cylinder 102 is supplied to the upper and

lower burners

114a and 115a through the

pipes

108 and 108a and used as combustion air. Combustion gas from each

combustion chamber

114, 115 provided with each

burner

114a, 115a is filled with a raw material formed in a raw material passage 117 formed between the outer cylinder 101 and the inner cylinder 102 as indicated by solid arrows in the figure. The gas flows upward in the bed, and a part of the combustion gas from the lower combustion chamber 115 flows downward as indicated by solid arrows in the figure.

A suction device 116 is provided on the side surface of the outer cylinder 101. This suction device 116 includes an injector mechanism, and is a raw material decomposition gas (from a raw material fired by cooling air rising from the lower portion of the outer cylinder 101, downward combustion gas from the lower combustion chamber 115, and downward combustion gas ( For example, CO ₂ gas) is sucked into the inner cylinder 102 side. The mixed gas of the cooling air, the combustion gas, and the gas generated by the decomposition of the raw material passes through the inner cylinder 102 and is guided to the pipe 118. The pipe 118 is connected to the upper end of the suction device 116, the upper end of the suction device 116 is further connected to a pipe 113 that supplies combustion air, and the lower end is connected to the lower combustion chamber 115.

Further, a fired product discharge device 119 for discharging the fired product is provided at the lower end portion of the outer cylinder 101, and a fired product cooling for cooling the fired product between the lower end portion of the inner tube 102 and the fired product discharge device 119. A band CZ is formed. Outside air is introduced into the fired product discharger 119 from the cooling air fan 119a, and cooling air flows upward in the fired product filled in the fired product cooling zone CZ as indicated by solid arrows in the figure. The fired product flows below the fired product discharge device 119 and is discharged to the outside, as indicated by broken line arrows in the figure.

In the raw material passage 117, a countercurrent zone is formed in which the hot gas and the raw material flow in opposite directions from the lower combustion chamber 115 and the lower gas chamber and the raw material flow in the same direction from the lower combustion chamber 115. A co-current calcination zone PFZ is formed between the lower combustion chamber 115 and the lower end portion of the inner cylinder 102, and a lower calcination zone DFZ and an upper combustion chamber 114 are formed between the lower combustion chamber 115 and the upper combustion chamber 114, respectively. Between the upper firing zone UFZ and the upper firing zone UFZ, the pre-tropical zone PZ is formed within the upper firing zone UFZ.

In the co-firing zone PFZ of the vertical firing furnace configured as described above, the combustion gas flows in parallel in the raw material and firing is performed, and the raw material is decomposed to generate gas (CO ₂ ). A gas generated by the decomposition of the combustion gas and the raw material (a mixed gas of the gas generated by the decomposition of the combustion gas and the raw material is referred to as a cocurrent gas) is mixed with cooling air and sucked into the suction device 116. It has a structure. The mixed gas sucked as described above is used as combustion air, heated by the combustion heat of the fuel, introduced again into the raw material packed layer of the raw material passage 117 in the furnace, and used as a firing heat source.

Note that the temperature of the cocurrent gas is, for example, as high as about 900 ° C. or more at the lower end of the cocurrent firing zone PFZ, and the cooling air after cooling the fired product is also about 500 ° C. to 890 ° C. For this reason, it is difficult to employ mechanical fans or the like as the mechanism of the suction device 116, and an injector mechanism is mainly used.

When this injector mechanism is adopted, the suction device 116 is a device for operating air (or operating gas) such as pressurized air (for example, pressure of 30 to 70 kPa, temperature of 400 ° C. to 500 ° C.) for operation. The suction pressure is generated by supplying a high-speed jet to the injector nozzle and forming a high-speed jet in the injector mechanism.

(1) Characteristics of the suction device 116 Since such a suction device 116 is basically composed of a refractory material, the dimensions of the suction device 116 cannot be varied during the operation of the furnace, and the dimensions are By being fixed, the following characteristics are provided. FIG. 5 is a diagram showing the relationship between the amount of mixed gas sucked by the suction device 116 and the suction pressure.

As is clear from FIG. 5, when the operating air amounts V1, V2, and V3 (V1 <V2 <V3) are constant, the suction pressure decreases as the mixed gas amount increases. Further, when the operating air amount is increased as V1 → V2 → V3, the suction pressure increases. Conversely, when the operating air amount is decreased as V3 → V2 → V1, the suction pressure decreases.

In the operation of a vertical firing furnace, the amount of mixed gas generally balances when the flow path resistance and suction pressure of the system become the same, so increasing the amount of operating air increases the amount of mixed gas. If the amount of working air is reduced, the amount of mixed gas can be reduced.

(2) Optimization of the amount of supplied air The amount of fuel supplied to the upper combustion chamber 114 and the lower combustion chamber 115 is optimal at a substantially constant ratio in order to enable the necessary heat distribution in the furnace. It is set to be a total amount. The combustion temperature in each of the

combustion chambers

114 and 115 is selected as the highest temperature within the allowable temperature optimum for the refractory and the firing raw material, and aims at efficient operation (that is, heat consumption is minimized). It will be. Therefore, it is required that good combustion is performed with as little air (or gas) as possible. Here, the amount of air for combustion is generally expressed by the following equation.

[Equation 1]
Va = m · Ao · Fw
Va: Total amount of air supplied to the furnace for combustion (Nm ³ / hr)
Fw: Amount of fuel supplied to the furnace (kg / hr)
Ao: Theoretical combustion air amount (Nm ³ / kg fuel): Theoretical air amount necessary for complete combustion of 1 kg of fuel m: Air coefficient

Usually, in a vertical combustion furnace, for example, the air coefficient m in the above equation is set to 1.1 to 1.37. That is, an air amount 1.1 to 1.37 times the theoretically required air amount is supplied. Although the optimum value of the air coefficient m differs depending on the type of fuel used, generally, minimizing the air coefficient m is required as one factor for minimizing heat consumption.

Also, since the operating air for the injector mechanism flows into the lower combustion chamber 115, it also affects the fuel combustion conditions in the lower combustion chamber 115. Furthermore, the mixed gas sucked similarly affects the temperature conditions in the combustion chamber and the state of the combustion flame. Specifically, in addition to the combustion air supplied to the burner, the air that flows into the lower combustion chamber 115 includes working air and cooling air for the fired product. These airs are directly related to the air coefficient m.

(3) Requirements from ensuring quality and reducing heat consumption Furthermore, from the viewpoint of ensuring the quality of the baked product, the amount of the cocurrent gas affects the firing of the raw material and consequently the quality of the baked product. It is. For this reason, it is essential to secure a certain amount. In addition, in order to reduce the heat consumption (fuel consumption), the outlet temperature of the fired product cooling zone CZ is lowered, and the heat lost from the fired product to the outside of the furnace (heat retained in the fired product) is reduced. It is necessary to increase the amount of heat recovery. For this purpose, it is necessary to secure a certain amount of cooling air.

By the way, the suction pressure in the characteristics of the suction device 116 of (1) described above is an element that determines the amount of cocurrent gas in the cocurrent firing zone. Since the co-current calcination zone is the final stage of the calcination process, the entire furnace is controlled so that the gas reaches a predetermined temperature at the downstream end thereof. Also from this fact, securing a certain amount of co-current gas is an extremely important factor in operating the firing furnace.
In order to secure a certain amount of co-current gas, it is necessary to secure a suction pressure, and the amount of air for operation to the injector mechanism is increased due to the characteristics of the suction device 116 having the injector mechanism (1) described above. Or it is necessary to reduce the amount of mixed gas. However, increasing the amount of operating air is contrary to the optimization of the amount of supplied air in (2) above, and reducing the amount of mixed gas will reduce the amount of cooling air in the fired product. ) Would be contrary to the requirements. For this reason, in many cases, the amount of mixed gas is reduced by reducing the amount of air for cooling the fired product while maintaining the amount of air for operation at the expense of the requirement (3). The operation that was made is carried out. As a result, an operation policy is adopted in which the suction pressure is increased to ensure a large amount of cocurrent gas.

Japanese Patent Laid-Open No. 57-122279

However, by reducing the amount of air for cooling the fired product as described above, the discharge temperature of the fired product is increased and the heat loss is increased. Although the cooling capacity of the fired product cooling zone CZ as described above is sufficiently secured, the cooling function provided due to the absolute shortage of the cooling air amount may not be sufficiently exhibited. For this reason, in a vertical firing furnace provided with a co-current firing zone using a suction device with an injector mechanism, the degree of freedom of operation control during operation may be limited.

In order to solve the above-mentioned problems, the present invention makes it possible to reduce the amount of air for operating the injector mechanism of the suction device and secure the amount of co-current gas while ensuring the amount of air for cooling the fired product, thereby discharging An object of the present invention is to provide a vertical firing furnace capable of effectively recovering the retained heat of the fired product and improving the degree of freedom of operation control.

In order to solve the above-described problems and achieve the object, the vertical firing furnace according to the present invention includes an outer cylinder arranged with the axial direction set as the vertical direction, and a coaxial arrangement inside the outer cylinder together with the outer cylinder. An inner cylinder that forms a double cylindrical structure and forms a raw material passage between the outer cylinder and a raw material filling layer that is installed at the upper end of the outer cylinder and that feeds the raw material into the raw material passage to form the raw material passage A charging device that is connected to the raw material passage and introduces combustion air to generate hot gas by a burner; and a part of the hot gas generated in the combustion chamber is passed through the raw material passage. A co-current firing zone in which the raw material and hot gas in the raw material packed bed on the lower side are fired while moving downward from the combustion chamber by suctioning to the outside of the outer tube via the lower end and the inner tube. A suction device that forms a front end of the co-current firing zone; There is a fired product discharge mechanism for discharging the fired product from the raw material passage, and a fired product introduction tube connected to the lower side of the fired product discharge mechanism to form a fired product filled layer inside, and below the fired product introduction tube A fired product cooling mechanism configured to house a fired product continuous in the fired product filled layer and to cool the housed fired product by introducing cooling air from the outside, and the fired product filled layer includes the cooling It has a resistance function to reduce the upward flow of working air.

The cooling air is used as a part of the combustion air in the combustion chamber after, for example, passing through a fired product inside the fired product cooling mechanism and exchanging heat. Further, the fired product cooling mechanism accommodates, for example, a fired product continuous in the fired product packed layer, and cools the stored fired product.

The fired product discharge mechanism is provided at, for example, a lower end portion of the outer cylinder, and a bottom plate in which a chute including a hole having a diameter smaller than the outer diameter of the inner cylinder is formed concentrically with the center line of the inner cylinder; A plurality of pushers arranged on the circumference of the outer cylinder in the vicinity of the lower end of the co-current firing zone and capable of reciprocating on the floor surface of the bottom plate toward the center of the chute, A surface connecting the peripheral edge of the lower end of the tube and the hole of the bottom plate is configured to form a free angle of repose of the fired product.

According to the present invention, it is possible to secure the amount of air for cooling the fired product while reducing the amount of air for operation of the injector mechanism of the suction device to ensure the amount of cocurrent gas, and the heat retained in the fired product discharged thereby Can be collected effectively and the degree of freedom of operation control can be improved.

It is a figure which shows the vertical type baking furnace which concerns on one Embodiment of this invention. In the co-current firing zone PFZ, the relationship between the co-current gas amount and the pressure loss, the relationship between the co-current gas amount and the mixed gas amount of the cooling air and co-current gas that has passed through the fired product cooling zone CZ, and the suction device It is a figure which shows collectively the relationship between the suction pressure to generate | occur | produce and the amount of mixed gas. It is a figure which shows the relationship between the air quantity for cooling of a baked product, a baked product temperature, and a baked product holding heat. It is a figure which shows the conventional vertical firing furnace of a double cylinder structure. It is a figure which shows the relationship between the amount of mixed gas attracted | sucked by the suction device, and suction pressure.

Hereinafter, an embodiment of a vertical firing furnace according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a view showing a vertical firing furnace according to an embodiment of the present invention. As shown in FIG. 1, the vertical firing furnace 1 according to the present embodiment includes a cylindrical outer cylinder 2 and an inner cylinder 3 that is concentrically suspended inside the cylindrical outer cylinder 2.

A feeding device 4 for a raw material supplied from the conveying device is provided at the upper end of the outer cylinder 2, and the upper end of the outer cylinder 2 is connected to an exhaust gas suction fan (not shown) via a pipe 5. . The exhaust gas from the outer cylinder 2 sucked by the exhaust gas suction fan is discharged into the atmosphere after dust is removed via a dust collector (not shown).

In the inner cylinder 3, a cooling air passage 6 for the inner cylinder 3 is formed, and cooling air is supplied to the passage from a cooling air fan 8 through a pipe 7. The cooled air that has cooled the inside of the inner cylinder 3 is collected in the pipe 9 and supplied to the combustion air heat exchanger 10 to be used as combustion air. The upper end portion of the inner cylinder 3 is connected to the upper end portions of the combustion air heat exchanger 10 and the operating air heat exchanger 12 via the pipe 11.

The lower ends of these

heat exchangers

10 and 12 are connected to an exhaust gas suction fan via a pipe 13. Outside the operating air heat exchanger 12, outside air is introduced from the blower 14, and heat is exchanged with the exhaust gas in the operating air heat exchanger 12. The outside air heated by this heat exchange is supplied to the upper burner 16 a of the upper combustion chamber 16, the lower burner 17 a of the lower combustion chamber 17, and the upper end of the suction device 18 provided in the outer cylinder 2 through the pipe 15. The air for combustion and the air for operating the suction device 18 are used.

The air that has cooled the inner cylinder 3 and heat-exchanged by the combustion air heat exchanger 10 is supplied to the upper and

lower burners

16a and 17a through the pipe 19 and used as combustion air. Combustion gas from each

combustion chamber

16, 17 provided with each

burner

16 a, 17 a is a raw material formed in a raw material passage 20 formed between the outer cylinder 2 and the inner cylinder 3 as indicated by solid arrows in the figure. The gas flows upward in the packed bed, and a part of the combustion gas from the lower combustion chamber 17 flows downward as indicated by solid arrows in the figure.

A suction device 18 is provided on the side surface of the outer cylinder 2. The suction device 18 includes an injector mechanism, and cooling air and a lower portion slightly raised from the fired product cooling device 21 provided below the inner cylinder 3 through the fired product packed layer 23 in the fired product introduction pipe 22. A raw material decomposition gas (for example, CO ₂ gas) generated from the raw material fired by the downward combustion gas and the downward combustion gas from the combustion chamber 17 is sucked through the inner cylinder 3 and the pipe 24.

The piping 24 is connected to the upper end portion of the suction device 18, the upper end portion of the suction device 18 is further connected to the piping 15 for supplying operating air, and the lower end portion is connected to the lower combustion chamber 17.

Also, a fired product discharge mechanism for discharging the fired product from the furnace is provided at the lower end of the outer cylinder 2. Further, a fired product cooling mechanism is provided below the fired product discharge mechanism to cool the fired product by introducing cooling air from the outside by the cooling air fan 25. The fired product discharge mechanism is configured as follows, for example.

Specifically, the fired product discharge mechanism includes a metal bottom plate 26 that covers the lower end side of the outer cylinder 2, a plurality of disposed on the circumference of the outer cylinder 2, on the floor surface of the bottom plate 26, and a packed bed A heat-resistant metal pusher 27 for moving the fired product at the lower end is provided. The bottom plate 26 has a structure in which a chute 26 b having a hole portion 26 a having a diameter smaller than the outer diameter of the inner cylinder 3 is formed concentrically with the center line of the inner cylinder 3.

The bottom plate 26 is lined with a refractory material and is configured to sufficiently withstand the temperature of a fired product or combustion gas. The pusher 27 has a structure capable of reciprocating as indicated by a solid line arrow in the figure toward the center of the chute 26b by a stroke variable piston 27a driven by a hydraulic cylinder.

In addition, the surface shown with the broken line which connects the lower end outer periphery end point of the inner cylinder 3 and the upper end inner periphery end point of the chute | shoot 26b of the baseplate 26 forms the free repose angle surface 31 of a baked product. As a result, the lowering of the raw material of the raw material packed layer formed in the raw material passage 20 can be made uniform on the annular surface.

Further, the fired product cooling mechanism specifically includes a fired product introduction pipe 22 disposed in an airtight state at the lower end portion of the chute 26 b via the expansion joint 28, and a lower end portion of the fired product introduction pipe 22. The fired product cooling device 21 is provided. In the fired product cooling device 21, the cooling air introduced by the cooling air fan 25 and having the air volume adjusted by the air volume adjusting damper 25 a is shown in FIG. Umbrella-shaped slits 21a that supply and distribute to 21b are provided.

The cooling air heat-exchanged with the fired product through the fired product packed layer 21b is adjusted in the air volume by the damper 30a for adjusting the air flow through the duct 30 connected to the upper space portion 21c of the fired product filled layer 21b. After that, it is supplied to the lower combustion chamber 17 to which the duct 30 is connected. A space between the lower end portion of the slit 21a of the fired product cooling device 21 and the lower end portion of the fired product introduction tube 22 is a fired product cooling zone CZ for cooling the fired product.

Further, in the raw material passage 20, a counter current zone in which the hot gas and the raw material flow in opposite directions from the lower combustion chamber 17 is formed, and the hot gas and the raw material flow in the same direction from the lower combustion chamber 17 in the lower portion. A flow zone is formed, and a co-current firing zone PFZ is formed between the lower combustion chamber 17 and the lower end portion of the inner cylinder 3, and a lower firing zone DFZ and an upper combustion chamber 16 are provided between the lower combustion chamber 17 and the upper combustion chamber 16, respectively. Between the upper firing zone UFZ and the upper firing zone UFZ, the pre-tropical zone PZ is formed within the upper firing zone UFZ.

In the vertical firing furnace 1 configured as described above, the raw material charged into the raw material passage 20 from the charging device 4 forms a packed bed from the bottom plate 26 to above the uppermost end of the pre-tropical PZ. The raw material is fired through the pre-tropical PZ and the firing zones UFZ, DFZ, and PFZ, and reaches the floor surface of the bottom plate 26 as a fired product. The reached fired product is discharged into the fired product introduction pipe 22 by the pusher 27 through the chute 26b and the expansion joint 28 with a preset discharge amount.

The fired product that has passed through the fired product introduction tube 22 is filled into the fired product cooling device 21, and the fired product filling layer 23 that continues from the fired product filled layer 21b is introduced into the fired product introduction tube 22 from the introduction tube height H1. Is formed with a lower filling layer height H2. Note that the lower end of the fired product introduction tube 22 is disposed so as to be in contact with the fired product filled layer 21b.

The fired product cooled in the fired product cooling device 21 is controlled to maintain the required height H2 of the fired product filling layer 23 and is discharged from the discharge unit 21d to the outside. Since the fired product packed layer 23 that continues from the fired product filled layer 21b is formed with a predetermined packed layer height H2, the cooling air that has passed through the fired product filled layer 21b is located above the fired product filled layer 23. It will be hardly guided.

That is, the fired product filling layer 23 exhibits an air sealing effect that seals the cooling air to some extent. In addition, since the diameter and the packed bed height H2 of the fired product introduction pipe 22 are configured so that the air sealing effect by the fired product is maximized, the gas flows through the fired product filled layer 23 and merges with the cocurrent gas. The amount of cooling air is small.

Therefore, the vertical firing furnace 1 according to the present embodiment reduces the amount of mixed gas due to the above-described configuration, so that the amount of air for operating the injector mechanism in the suction device 18 can be reduced. Usually, the temperature of the working air is 450 ° C. to 480 ° C., and the amount of heat supplied to the furnace by the working air decreases in proportion to the amount of reduction of the working air.

In the vertical firing furnace 1, a part of the combustion gas in the furnace passes through the piping 11 through the introduction path 3 a provided in the inner cylinder 3 at the upper end position of the upper firing zone UFZ, and the combustion air heat exchanger. 10 and the operating air heat exchanger 12 respectively. Therefore, even if the working air heat exchanger 12 is downsized, the working air can be sufficiently heated.

In this case, since the amount of combustion gas introduced into the miniaturized operating air heat exchanger 12 can be reduced, surplus combustion gas generated thereby is introduced into the combustion air heat exchanger 10, and each burner 16a. , 17a used as combustion air, the cooled air in the inner cylinder 3 (for example, having a temperature of 190 ° C. to 210 ° C.) is heated in the heat exchanger 10 to have a temperature of 390 ° C. to 430 ° C. It becomes possible to supply working air.

Here, as an explanation of the vertical firing furnace 1 configured as described above, first, the reduction of the amount of air for operation of the suction device 18 provided with an injector mechanism will be described. In the following, as a specific example, a case where the vertical firing furnace 1 having a firing capacity of 300 t / day is producing a fired product of 300 t / day will be described as an example. As a premise, the importance of cocurrent gas in a vertical firing furnace will be briefly described.

That is, the co-current firing zone has a function of firing the raw material by flowing the combustion gas along the descending direction of the raw material in the raw material passage 20 and is in the final stage of the firing step. Therefore, when a certain amount of co-current gas flows, the temperature of the co-current gas, which is a mixed gas of the combustion gas at the lower end of the co-current calcining zone and the raw material decomposition gas generated from the calcined raw material, is monitored. If the entire furnace is adjusted so that the temperature becomes a predetermined temperature, the final result is expressed as the temperature at the lower end of the co-current firing zone.

That is, it can be said that it is empirically found that when the temperature of the co-current gas coincides with a predetermined temperature, the finally obtained fired product has a predetermined quality. As described above, since the cocurrent gas plays an important role in the operation of the furnace, it is desired to ensure a stable amount of the cocurrent gas in the actual operation.

Under this assumption, the reduction of the working air volume will be explained. FIG. 2 shows the relationship between the cocurrent gas amount and pressure loss in the cocurrent calcination zone, the relationship between the cocurrent gas amount and the mixed gas amount of cooling air and cocurrent gas that has passed through the baked product cooling zone, and the suction device. It is a figure which shows collectively the relationship between the suction pressure and the amount of mixed gas which generate | occur | produce.

In addition, in the graph A of FIG. 2, it turns out that a cocurrent gas amount (Nm < ³ > / hr) increases and a pressure loss also increases. Further, the line α in the graph B shows the relationship between the cocurrent gas amount and the mixed gas amount when the cooling air amount is 8,000 Nm ³ / hr and the constant amount flows, and the line β is the cooling air amount. Shows the relationship between the amount of co-current gas and the amount of mixed gas when is 0, and the line γ shows the amount of co-current gas and the amount of mixed gas when the amount of cooling air is 600 Nm ³ / hr and a constant amount flows. Showing the relationship. This line γ corresponds to the vertical firing furnace 1 according to the present embodiment, and the cooling air amount of 600 Nm ³ / hr indicates the amount of leakage from the fired product packed layer 23.

Graph C also shows the suction pressure at the lower end of the co-current firing zone along with the suction pressure generated by the suction device. Lines A1, A2, and A3 show the suction pressure generated by the suction device, and the lines B1, B2 and B3 respectively show the suction pressure at the lower end of the co-current firing zone. The suction pressure at the lower end of the co-current firing zone is obtained by subtracting the pressure loss between the lower end and the suction device from the suction pressure generated by the suction device. It can be seen that these suction pressures increase as the amount of mixed gas decreases.

In graph C, line A1 shows an example of the suction pressure generated by the suction device in the conventional furnace, and line B1 shows an example of the suction pressure at the lower end of the co-current firing zone in this conventional furnace, and the amount of operating air is It is a constant amount of 4,900 Nm ³ / hr. Similarly, line A3 shows the suction pressure when the operating air amount is reduced in the conventional furnace, and line B3 shows an example of the suction pressure at the lower end of the co-current firing zone in this case. in which was reduced to 3,000 nm ³ / hr from 900 nm ³ / hr.

Further, the lines A2 and B2 are suctions generated by the newly designed suction device 18 corresponding to the small mixed gas amount and the working air amount applied in the vertical firing furnace 1 according to the present embodiment. The pressure and the suction pressure at the lower end of the co-current calcination zone PFZ are shown, respectively, and the working air amount is 2,500 Nm ³ / hr and a constant amount.

In an actual vertical firing furnace, the suction pressure at the lower end of the co-current calcining zone shown in graph C and the pressure loss in the co-current calcining zone shown in graph A coincided as shown by the horizontal line D1. Balance with. And the intersection of the line D3 drawn perpendicularly | vertically as shown by the solid line arrow in a figure from the coincidence pressure point D2 in the graph A, and a horizontal axis becomes cocurrent gas amount.

In the graphs B and C, the ones indicated by the broken-line arrows in the figure indicate the amount of co-current gas in the case of the line γ where the cooling air amount is 600 Nm ³ / hr (actually equivalent to the leak amount) in the graph B. It shows the suction pressure at the lower end of the co-current firing zone. From these facts, by reducing the amount of mixed gas, it is possible to generate suction pressure at the lower end of the same co-current firing zone as in the case where the amount of mixed gas is not reduced with a small amount of working air. I can say that. Therefore, it is possible to reduce the amount of working air while ensuring the amount of cocurrent gas.

Note that the pressure loss in the graph A is not affected by the cooling air, and is caused only by the cocurrent gas unless the raw material properties are changed. Therefore, if the suction pressure at the lower end of the co-current firing zone is determined, the co-current gas amount can be read from this graph A. Further, the pressure loss in the mixed gas passage from the lower end to the suction device is caused by the mixed gas of the cocurrent gas and the cooling air.

Therefore, once the suction pressure in the suction device is determined, the suction pressure at the lower end of the co-current firing zone shown in graph C is calculated by subtracting the pressure loss in the passage from this pressure, and the amount of co-current gas is grasped. It becomes possible to do. As shown in this graph C, when the working air amount is constant, the suction pressure of the suction device increases as the mixed gas amount decreases.

Since the importance of the cocurrent gas is as described above, when the cocurrent gas and the cooling air are compared, priority is given to securing the cocurrent gas amount. That is, the amount of mixed gas is reduced by reducing the amount of cooling air, and the suction pressure of the suction device is kept high (as a result, the suction pressure at the lower end of the co-current firing zone is kept high), thereby forming a cocurrent gas. The amount can be increased.

As described above, the lines A1 and B1 of the graph C shown in FIG. 2 indicate the respective suction pressures in the conventional furnace, and therefore, based on these lines A1 and B1, for example, the graphs A to B shown in FIG. from C, it is possible to obtain co-current gas amount of about 11,000Nm ³ / hr, a gas mixture of about 19,400Nm ³ / hr, and the specific numerical values of the cooling air quantity of about 8,400Nm ³ / hr .

Note that the vertical firing furnace 1 according to the present embodiment has a structure in which the co-current firing zone PFZ and the fired product cooling device 21 are separately arranged, and in the fired product introduction pipe 22 disposed at an intermediate position between them. By forming the fired product filling layer 23 having a desired filling layer height H2, the air sealing effect as described above is obtained.

For this reason, in an ideal state, only the cocurrent gas is sucked into the suction device 18, but in reality, the cooling air cannot be completely sealed. It is necessary to design with the cooling air that has passed into the co-current gas in mind.

In consideration of the above circumstances, each suction pressure in the vertical firing furnace 1 according to the present embodiment designed on the condition that the amount of cocurrent gas is the same as that of the conventional furnace is shown in the graph C of FIG. As shown by lines A2 and B2. Then, based on these lines A2, B2, from each of the graphs A ~ C, co-current gas amount of about 11,000Nm ³ / hr, a gas mixture of about 11,600Nm ³ / hr, and about 600 Nm ³ / hr It becomes possible to obtain a specific numerical value of the cooling air amount.

As a result, working airflow of the suction device, 2,500 nm ³ / hr next if the vertical firing furnace 1, since the 4,900Nm ³ / hr in the case of conventional furnaces, the difference as compared with the conventional furnace -2,400 Nm ³ / hr. The degree of freedom of the cooling air amount is that of the vertical firing furnace 1 (4,900-2,500) when the cooling air amount in the conventional furnace is Vc (Nm ³ / hr) in actual operation. since + a Vc ^(Nm 3 / hr), it is possible that differences in comparison with the conventional furnace to obtain a range of + 2,400Nm ³ / hr.

Therefore, for example, if the total amount of air introduced into the lower combustion chamber 17 is constant (that is, the air coefficient m in the lower combustion chamber 17 is not changed), it is about 2,400 Nm ³ / hr (that is, suction) compared to the conventional furnace. It is possible to introduce a large amount of cooling air into the fired product cooling device 21 up to a reduction in the amount of operating air of the device 18.

Next, heat recovery from the fired product will be described. FIG. 3 is a diagram showing the relationship among the amount of air for cooling the fired product, the temperature of the fired product, and the heat retained in the fired product. In FIG. 3, a curve M is a related curve between the cooling air amount and the calcined product temperature, and a curve N is a related curve between the cooling air amount and the calcined product retained heat. The calcined product holding heat is calculated on the basis of 20 ° C.

As shown in FIG. 3, for example, when the cooling air amount is 6,700 Nm ³ / hr, the calcined product temperature is 150 ° C. from curve M, and the calcined product holding heat is 25 kcal / kg from curve N. Here, when the amount of cooling air is reduced to 6,140 Nm ³ / hr, the calcined product temperature becomes 200 ° C. from curve M, and the calcined product holding heat rises from curve N to 35 kcal / kg. That is, when the amount of cooling air increases by 560 Nm ³ / hr, the fired product holding heat decreases by 10 kcal / kg. These relationships are shown in Table 1 below.

Vc represents the amount of cooling air in the conventional furnace, and V and Vc + 2,400 represent the target cooling air amount and the maximum cooling air amount in the vertical firing furnace 1 according to the present embodiment, respectively.

As apparent from Table 1 and FIG. 3, the calcined product possessed heat 35 kcal / kg in the case of the cooling air amount Vc and the calcined product retained heat 9.5 kcal / kg in the case of the maximum cooling air amount Vc + 2,400 The difference is 25.5 kcal / kg. Further, the difference between the calcined product retained heat in the case of the cooling air amount Vc and the calcined product retained heat in the case of the target cooling air amount V of 25 kcal / kg is 10 kcal / kg. The difference between the calcined product retained heat in the case of the target cooling air amount V and the calcined product retained heat in the case of the maximum cooling air amount Vc + 2,400 is 15.5 kcal / kg.

Therefore, in the vertical firing furnace 1 according to the present embodiment, it is possible to recover heat of a maximum of 25.5 kcal / kg fired product (amount of heat per 1 kg of the fired product) and a minimum of 10 kcal / kg fired product. . Further, when the furnace is operated at the maximum capacity, the cooling air amount may be insufficient with respect to the production amount of the baked product.

Even in such a case, the vertical firing furnace 1 increases the cooling air amount V of the fired product by about 2,400 Nm ³ / hr as compared with the cooling air amount Vc of the conventional furnace as described above. Therefore, it is possible to provide a sufficient cooling capacity. In addition, when the cooling capacity is provided, it can be expected that the heat recovery amount is larger than the heat recovery amount (25.5 kcal / kg calcined product to 10 kcal / kg calcined product) described above.

Thus, by increasing the heat recovery amount of the baked product, the heat consumption is reduced, and various effects can be obtained. Further, by reducing the operating air amount of the suction device 18, as described above, surplus combustion gas having a heat amount corresponding to the heat amount held by the operating air in the conventional furnace is generated.

For example, when the reduction amount of the working air amount in the vertical firing furnace 1 according to the present embodiment is 2,400 Nm ³ / hr and the temperature of the working air is 480 ° C., the excess heat amount calculated on the basis of 20 ° C. The amount of decrease in heat brought into the furnace means 355,488 kcal / hr, and the amount of decrease in carry heat per kg of the calcined product becomes 28.4 kcal / kg calcined product.

Since the cooled air whose temperature has been increased by cooling the inner cylinder 3 in the conventional furnace is used as combustion air in the burner, the amount of cooled air is 5,500 Nm ³ / hr, and the average supply temperature to the burner is 200 ° C. In this case, the retained heat amount of the cooled air is 309,870 kcal / hr.

Therefore, the excess heat amount due to the decrease in the amount of operating air is effectively used in the heat exchanger 10, and the cooled air in the inner cylinder 3 is heated to generate combustion heat having a retained heat of 665,358 kcal / hr and a temperature of about 400 ° C. If it supplies to the

burners

16a and 17a, it will become possible to compensate the reduction | decrease of the carrying-in heat of working air. That is, all the recovered heat recovered from the fired product described above contributes to a reduction in the heat consumption of the furnace.

In the above-described embodiment, the vertical firing furnace 1 having a firing capacity of 300 t / day has been described. However, the present invention can be similarly applied to other furnaces. In addition, the heat recovery amount of 25.5 kcal / kg calcined product (amount of heat per 1 kg of calcined product) and the minimum 10 kcal / kg calcined product was explained. Depending on the required quality, there is a change, but on the premise that it is a 930 to 980 kcal / kg calcined product, for example, based on the 955 kcal / kg calcined product, the heat consumption in the vertical firing furnace 1 is 1.0 to It can be reduced by about 2.6%.

According to the vertical firing furnace 1 according to the present embodiment as described above, the following effects can be obtained.
(1) The overall heat consumption of the vertical firing furnace 1 can be reduced by 1.0 to 2.6% for improvement.
(2) The degree of freedom of operation control during operation of the vertical firing furnace 1 can be improved.
(3) Since the combustion air supplied to each

burner

16a, 17a of the vertical firing furnace 1 can be heated, the combustion state of the fuel can be improved satisfactorily.
(4) Since the fired product can be sufficiently cooled by the fired product cooling device 21 of the vertical firing furnace 1, a heat-resistant belt conveyor is used as a transport conveyor for transporting the fired product discharged from the discharge unit 21d. It can be adopted with heart.
(5) Since the fired product cooling device 21 of the vertical firing furnace 1 is separated from the furnace, an ideal cooling device can be designed, and the cooling device can be downsized.
Therefore, the amount of air for operating the injector mechanism of the suction device 18 of the vertical firing furnace 1 can be reduced to ensure the amount of co-current gas while ensuring the amount of air for cooling the fired product, and firing discharged from the furnace. The retained heat of the product can be effectively recovered by the fired product cooling device 21 to improve the degree of freedom of operation control of the operation.

DESCRIPTION OF SYMBOLS 1 Vertical firing furnace 2 Outer cylinder 3 Inner cylinder 4 Charging device 10 Combustion air heat exchanger 12 Actuation air heat exchanger 16 Upper combustion chamber 16a Upper burner 17 Lower combustion chamber 17a Lower burner 18 Suction device 20 Raw material passage 21 Firing Product cooling device 21b Firing product filling layer 22 Firing product introduction tube 23 Firing product filling layer 26 Bottom plate 27 Pusher 28 Expansion joint 30 Duct

Claims

An outer cylinder arranged with the axial direction as the vertical direction;
An inner cylinder that is coaxially arranged inside the outer cylinder and forms a double cylindrical structure with the outer cylinder to form a raw material passage between the outer cylinder,
A charging device installed at the upper end of the outer cylinder and charging a raw material into the raw material passage to form a raw material packed layer in the raw material passage;
A combustion chamber that is formed in connection with the raw material passage and introduces combustion air to generate a hot gas by a burner;
A part of the hot gas generated in the combustion chamber is sucked to the outside of the outer cylinder through the lower end portion of the raw material passage and the inner cylinder, so that the raw material of the raw material packed bed below the combustion chamber And a suction device that forms a co-current firing zone in which the hot gas is fired while moving downwards,
A fired product discharge mechanism that is provided at a lower end of the co-current firing zone and discharges the fired product from the raw material passage;
It has a fired product introduction pipe connected to the lower side of the fired product discharge mechanism to form a fired product filled layer inside, and cooling air is introduced from the outside below the fired product introduction pipe to cool the fired product. A fired product cooling mechanism,
The fired product packed layer has a resistance function of reducing the upward flow of the cooling air.
2. The soot according to claim 1, wherein the cooling air is used as a part of combustion air in the combustion chamber after passing through a fired product inside the fired product cooling mechanism and exchanging heat. Mold firing furnace.
3. The vertical firing furnace according to claim 1, wherein the fired product cooling mechanism houses a fired product continuous in the fired product packed layer and cools the fired product contained therein. 4.
The fired product discharge mechanism is:
A bottom plate provided at a lower end portion of the outer cylinder, and a chute provided with a hole having a diameter smaller than the outer diameter of the inner cylinder, concentrically with the center line of the inner cylinder;
A plurality of pushers arranged on the circumference of the outer cylinder in the vicinity of the lower end portion of the co-current firing zone, and capable of reciprocating on the floor surface of the bottom plate toward the center of the chute,
The surface connecting the outer peripheral edge of the lower end of the inner cylinder and the hole of the bottom plate is configured to form a free angle of repose of the fired product. The vertical firing furnace according to item.