JPH0424628B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-system preheating device for powdered raw materials such as cement, alumina, lime, etc.

(Prior Art) Conventionally, powder raw material preheating devices have been configured in various ways, some of which are configured as follows. In other words, fuel is combusted in the calciner using an exhaust gas system preheating device that mainly uses the exhaust gas from the calciner, and high-temperature exhaust air from the cooling device for fired products, and the combustion gas generated by this is mainly used. There is a preheating device that has multiple systems including combustion gas system preheating devices to be used.

As mentioned above, in the calcining method in which each preheating device is installed in parallel with the gas flow, the combustion furnace exhaust gas does not pass through the calciner located in the combustion gas system, so the fuel is combusted in the calciner. It has the advantage that it has excellent performance and that the calciner can be constructed compactly.

However, in the case of a preheating device with multiple systems as described above, in order to balance the thermal work per powder raw material processed in each system and to highly calcinate the powder raw materials in both systems, it is necessary to Conventionally, the powder raw material passing through the preheating device is configured to pass through the lowermost heat exchange stages of both preheating devices in series.

This conventional example will be specifically explained with reference to a system diagram of a cement raw material firing apparatus shown in FIG.

In the figure, reference numeral 1 denotes a firing furnace for producing clinker by firing cement raw materials, and 2 denotes a cooling device that cools the clinker discharged from the firing furnace 1 with an air flow.

The firing furnace 1 is connected to an exhaust gas system preheating device 3 that preheats the powder raw material with the exhaust gas from the firing furnace 1, and the cooling device 2 burns fuel using the exhaust air from the cooling device 2. A combustion gas system preheating device 4 for preheating the powder raw material with this combustion gas is connected. Further, the firing furnace 1 is connected to a cooling device 2 through an air passage 6.
The hot exhaust air from the kiln 1 is fed through the air passage 6 into the kiln 1 for fuel combustion in the kiln 1.

The exhaust gas system preheating device 3 will be explained.

This exhaust gas system preheating device 3 has powder separators C ₁₁ to _{C 14} such as cyclones stacked vertically, and the gas discharge port of each powder separator and the gas of other powder separators above this powder separator are connected to each other. The inlets are connected to each other by gas ducts 7a. Furthermore, the gas outlet of the firing furnace 1 and the gas inlet of the powder separator _C14 at the lowest stage are also connected by a gas duct 7a. Furthermore, the gas outlet of the powder separator C ₁₁ at the top stage is connected to the exhaust gas fan 12a by a gas duct 7b.

The gas inlets of each powder separator except for the top and bottom powder separators C ₁₁ and C ₁₄ are connected to the powder discharge ports of the other powder separators above these powder separators by a raw material chute 13, respectively. Ru. In addition, the gas inlet side gas duct 7a of the powder separator C ₁₁ on the top stage
A raw material supply port 16 into which powdered raw materials are introduced is provided. On the other hand, the powder discharge port of the powder separator C ₁₄ at the lowest stage is connected to the firing furnace 1 through a raw material chute 14 .

Next, the combustion gas system preheating device 4 will be explained.

This combustion gas system preheating device 4 is constructed in the same manner as the exhaust gas system preheating device 3, and includes powder separators C ₂₁ to _{C 24} stacked in the vertical direction and an exhaust gas fan 12b, and a gas duct connecting these. 7a, 7b and a raw material chute 13.
In addition, in this combustion gas system preheating device 4, the gas inlet side gas duct 7a of the lowest stage powder separator C ₂₄ ,
Powder separator C ₂₃ located above this powder separator C ₂₄
A calcining furnace 8 is interposed between the powder outlet and the powder outlet for preheating the powder raw material by burning fuel using the exhaust air from the cooling device 2. This calciner 8 is connected to a cooling device 2 by an exhaust air duct 9 and is provided with an independent fuel supply device 10 .

Further, the powder discharge port of the second-stage powder separator C ₁₃ from the bottom in the exhaust gas system preheating device 3 is connected to the raw material chute 15 to the calciner 8 of the combustion gas system preheating device 4.
The powder discharge port of the powder separator C ₂₄ of the combustion gas system preheating device 4 is connected to the gas inlet side gas duct 7a of the powder separator C ₁₄ of the exhaust gas system preheating device 3 by the raw material chute 18. .

Then, the high-temperature exhaust air that has cooled the clinker in the cooling device 2 is burned in the kiln 1 to become exhaust gas, and in the exhaust gas system preheating device 3, it is sucked by the exhaust gas fan 12a and sent from the powder separator C ₁₄ at the lowest stage. Flowed to the top powder separator C ₁₁ .
In the combustion gas system preheating device 4, the exhaust air from the cooling device 2 is burned in the calciner 8, and this gas is sucked by the exhaust gas fan 12b and sent from the powder separator C 24 at the lowest stage to the powder separator C ₂₄ at the top stage. The exhaust gas flows into powder separator C ₂₁ (the flow of exhaust gas is indicated by solid arrows in the figure).

On the other hand, the powder raw materials inputted from the respective raw material supply ports 16 and 16 flow from the powder separators C ₁₁ and C ₂₁ at the top stage of each preheating device 3 and 4 toward the lower stage, and flow into the firing furnace 1.
The powder is fired into clinker, cooled by a cooling device 2, and transferred to the next process (the flow of the powder raw material is indicated by broken line arrows in the figure).

In the above case, the entire amount of preheated powder raw material discharged from the second stage powder separator C ₁₃ from the bottom in the exhaust gas system preheating device 3 is transferred to the combustion gas system preheating device 4.
is supplied to the calcining furnace 8. Therefore, the powdered raw material is partially calcined in the calciner 8 together with the powdered raw material from the powder separator C ₂₃ in the second stage from the bottom of the combustion gas system preheating device 4, and then lowest stage powder separator C ₂₄ and exhaust gas system preheating device 3
While passing in series through the lowermost stage powder separator C ₁₄ , a higher degree of calcination is achieved and the powder is supplied to the firing furnace 1 . In addition, the powder separator C ₁₃ in the second stage from the bottom of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4,
Contrary to the above, the preheated powder raw material discharged from C ₂₃ is passed in series from the lowest heat exchange stage of the exhaust gas system preheater 3 to the lowest heat exchange stage of the combustion gas system preheater 4. In this case, a similar effect of promoting calcination can be obtained.

(Problem to be solved by the invention) By the way, in the calcining reaction of limestone particles, that is, the decarboxylation reaction (CaCO ₃ → CaO + CO ₂ ), the temperature of the particles and the partial pressure of carbon dioxide in the atmospheric gas are the same. In some cases, finer powders require a shorter reaction time, ie, shorter residence time in the hot gas, while coarser powders require a longer residence time in proportion to their particle size. On the other hand, the recarbonation reaction (CaO + CO ₂ →
Regarding CaCO ₃ ), it is said that finer powders are more likely to be recarbonated, and coarser powders are less likely to be recarbonated, similarly to the above.

In addition, the collection efficiency of powdered raw materials by the powder separator is lower for finer powders and higher for coarser grained powders. , fine powder is not easily collected. Therefore, the fine powder is circulated to the upper powder separator together with the exhaust gas from the powder separator. Then, when the temperature of the powder raw material decreases in the upper stage, the fine powder absorbs carbon dioxide gas in the gas, causing a recarbonation reaction and generating heat, which increases the temperature of the exhaust gas from the preheating device. This may cause operational problems such as clogging of the powder raw material in the powder separator in the lower stage.

That is, in the above conventional example, the exhaust gas system preheating device 3
The preheated powder raw materials discharged from the second-stage powder separators C ₁₃ and C ₂₃ from the bottom of the combustion gas system preheating device 4 are both supplied to the calcining furnace 8 and partially calcined, and the above-mentioned combustion A high degree of calcination is achieved by passing in series through the lowermost heat exchange stages of the gas system preheater 4 and the exhaust gas system preheater 3.

However, the above-mentioned powder raw material contains fine powder and coarse powder, and for the coarse powder, the lowermost heat exchange stage of the preheating device of both systems is connected in series to achieve calcination. For fine powder, passing through the lowest heat exchange stage of either the exhaust gas system preheater 3 or the combustion gas system preheater 4 is sufficient to achieve a high degree of calcination. This eliminates the need to pass through the bottom stage multiple times.

Therefore, in the conventional configuration described above, fine powder that is not easily collected by the powder separator can also be used in the combustion gas system preheating device 4.
and the lowermost heat exchange stage of the exhaust gas system preheating device 3 in series, fine powder that cannot be completely collected by the powder separator C ₂₄ and the powder separator C ₁₄ is transferred to both systems each time. Circulate to the upper stage of the preheating device,
By passing through this bottom stage multiple times,
In addition to causing an extra pressure loss of hot gas, the amount of recarbonation due to the circulation of fine powder to the upper stage increases, which may impede thermal economy and cause operational problems.

(Objective of the Invention) The present invention has been made in view of the above-mentioned circumstances, and is capable of achieving a high degree of calcination of the coarse powder in the powder raw material in a preheating device, as well as achieving a high degree of calcination of the coarse powder in the powder raw material. The purpose is to prevent an increase in pressure loss and recarbonation due to recirculation within the preheating device.

(Structure of the Invention) The present invention for achieving the above object is characterized by a powder separator located at the bottom of at least one of the preheating devices consisting of an exhaust gas system preheating device and a combustion gas system preheating device. is a classifier that classifies the powder raw material into fine powder and coarse powder, and the fine powder in the powder raw material passes through the lowermost powder separator of one preheating device, and the coarse powder The fine grain discharge port and the coarse grain discharge port of the classifier are respectively connected to the path of each preheating device so that the particles pass through the lowermost stage powder separator of the preheating device in series.

(Embodiments) Hereinafter, first to ninth embodiments of the present invention will be described with reference to FIGS. 1 to 12. The basic configuration of each of the above embodiments is the same as that of the conventional example shown in FIG. Therefore, items with the same configuration are given the same reference numerals.
The explanation will be omitted.

1 to 3 show a first embodiment.

In the figure, the lowest stage powder separator C' ₂₄ in the combustion gas system preheating device 4 is a classifier that classifies the powder raw material into fine powder and coarse powder. This classifier is composed of a cyclone-shaped fine-grain classifier 19 and a pocket-shaped coarse-grain classifier 20 connected to the fine-grain classifier 19. The fine grain discharge port 21 of the fine grain classifier 19 is connected to the firing furnace 1 through a raw material chute 23, and the coarse grain discharge port 22 of the coarse grain classifier 20 is connected to the lowest stage powder of the exhaust gas system preheating device 3 through the raw material chute 18. It is connected to the gas duct 7a on the gas inlet side of the separator _C14 .

Then, the powder raw materials inputted from the raw material supply ports 16, 16 of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 are sent to the powder separator C ₁₃ and the powder separator C ₂₃ .
is supplied to the calciner 8 from the fuel supply device 10.
The fuel is partially calcined by absorbing the combustion heat of the fuel supplied from the fuel. This powder raw material is then passed through a powder separator.
After passing through the gas duct 7a on the inlet side of C' ₂₄ , the powder is separated into fine powder and coarse powder by the powder separator C' ₂₄ . The above-mentioned fine powder is put into the firing furnace 1, and
The coarse powder is sent to the powder separator of the exhaust gas system preheating device 3.
The gas is introduced into the inlet side gas duct 7a of _C14 .

In the case of the above structure, the fine powder can be highly calcined in the calciner 8 and the gas duct 7a on the inlet side of the powder separator C' ₂₄ . On the other hand, although the coarse powder is not sufficiently calcined in the calcining furnace 8 and the inlet side gas duct 7a of the powder separator C' ₂₄ , it continues to be calcined in the powder separator at the lowest stage in the exhaust gas system preheating device 3.
A high degree of calcination is achieved in the inlet side gas duct 7a of _C14 .

Here, the powder separator _C'24 will be explained.

This fine particle classifier 19 is shaped like a cyclone and has a cyclone body 25. This cyclone main body 25 is formed of a cylindrical body 28 whose upper part is closed with a ceiling plate 27, and an inverted conical cylinder 29 connected to the lower end of this cylindrical body 28, and the lower end of this inverted conical cylinder 29 This is the discharge port 21 . Further, a gas duct 7a which is a gas inlet is connected to the upper part of the cylindrical body 28 in the tangential direction or circumferential direction, and a gas duct 7a which is a gas outlet is connected to the ceiling plate 27 almost coaxially with the cylindrical body 28. Connected.

Further, the coarse particle classifier 20 has a pocket portion 26 that communicates with the inner wall surface of the cylindrical body 28. This pocket part 26 also has a cylindrical body 32 closed with an upper ceiling plate 31, like the sacrone main body 25,
An inverted conical cylinder 33 connected to the lower end of this cylinder 32
The lower end of this inverted conical cylinder 33 serves as the coarse particle outlet 22. Further, the cyclone main body 25 and the pocket portion 26 are communicated via a short pipe 34.

In addition, from the fine particle classifier 19 to the coarse particle classifier 20
An adjustment plate 37 for adjusting the amount of coarse powder flowing into the short pipe 34 is provided in the middle of the short pipe 34. Gate valves 38 and 39 are opened and closed to block passage of, for example, gas within the raw material chute 23 and 18.

The powdered raw material is fed into the calciner 8 via the raw material chute 15 from the powder separator C ₁₃ in the second stage from the bottom of the exhaust gas system preheating device 3, and the powder separator C 13 in the second stage from the bottom of the combustion gas system preheating device 4 The powder raw material input from the powder separator C ₂₃ to the calciner 8 via the raw material chute 13 is transferred from the calciner 8 to the gas inlet side gas duct 7a of the powder separator C' ₂₄ , which is the classifier. This powder raw material is then introduced into the powder separator C' ₂₄ while exchanging heat with the gas. Then, the powder raw material along with the gas flows into the cylindrical body 28.
Rotate inside. Then, due to the centrifugal force accompanying this rotation, the coarse powder passes through the inner hole of the short tube 34 provided on the inner wall surface of the cylindrical body 28 and is collected in the pocket portion 26, and then falls due to its own weight and becomes coarse. Grain outlet 2
It is discharged from 2.

On the other hand, since the centrifugal force of fine powder is small, the cylindrical body 2
8, and thus moves from the cylindrical body 28 side to the inverted conical cylinder 29 side without being collected by the pocket part 26. Then, the gas in the swirling flow is reversed upward within the inverted conical cylinder 29, passes through the center of the swirling flow, and is discharged from the upper gas duct 7a. In addition, the fine powder in the swirling flow is transferred to the inverted conical cylinder 2.
The small particles are subjected to a large centrifugal force due to a small turning radius within the fine particles 9, descend while turning along the inner peripheral surface of the inverted conical cylinder 29, and are discharged from the fine particle discharge port 21.

In the powder separator C' ₂₄ having the above configuration, coarse powder is separated from the powder raw material using the swirling flow of hot gas introduced into the powder separator C' ₂₄ . Therefore, coarse powder can be separated without increasing the pressure loss of the preheating device.

Further, since the coarse powder is separated from the powder raw material using the centrifugal force applied to the powder raw material when it rotates within the cyclone body 25, the efficiency of separating the coarse powder by the pocket portion 26 is high.

At this time, the amount of coarse powder collected into the pocket portion 26 via the short tube 34 can be adjusted as desired by adjusting the insertion length of the adjusting plate 37 provided on the short tube 34. .

FIG. 4 shows a second embodiment, in which a vertically oriented pivot shaft 41 is rotatably provided in the short tube 34 of the powder separator C' ₂₄ , and a deflection plate 42 is attached to this pivot shaft 41. It will be done.

The amount of coarse powder collected in the pocket portion 26 is adjusted by rotating the warp plate 42 (as shown by the two-dot chain line in the figure).

FIG. 5 shows a third embodiment, in which a concave groove 43 is formed in the cylindrical body 28 of the powder separator C' ₂₄ , extending along the outer peripheral surface of the cylindrical body 28 on the upstream side of the gas swirling flow rather than the short pipe 34. be done. A vertically oriented pivot shaft 44 is rotatably provided at the gas upstream end of the groove 43, and a deflection plate 45 is attached to this pivot shaft 44.

The amount of coarse powder collected in the pocket portion 26 is adjusted by rotating the warp plate 45 (as shown by the two-dot chain line in the figure).

FIG. 6 shows a fourth embodiment, in which a pocket portion 26 is provided on the side surface of the cylindrical body 28 below a gas inlet side gas duct 7a connected to the cylindrical body 28 in a spiral manner in the circumferential direction. With this configuration, the powder raw material is sufficiently urged toward the inner circumferential surface of the cylindrical body 28 by the centrifugal force due to the swirling flow. Therefore, a sufficient amount of powder raw material can be collected in the pocket portion 26. Further, the position of the pocket portion 26 can be freely selected relative to the gas duct 7a in the circumferential direction on the side surface of the cylindrical body 28 without interfering with the gas duct 7a. Therefore, by arranging the pocket portion 26 on the side surface closer to the exhaust gas system preheating device 3, connection with the exhaust gas system preheating device 3 can be easily performed.

FIG. 7 shows a fifth embodiment, in which a pocket portion 26 is provided on the side surface of an inverted conical cylinder 29 of a powder separator _C'24 . In addition, the same effect as in the above embodiment can be obtained even if the pocket portion 26 is provided spanning from the cylindrical body 28 to the inverted conical cylinder 29. Therefore,
In this manner, the amount and particle size distribution of the powder raw material to be separated can be adjusted by determining at what height of the powder separator the pocket portion 26 is provided.

In addition to the locations shown in the above embodiments, the pocket portion 26 may be provided at any location in the vertical direction or circumferential direction as long as it is on the side wall of the cyclone-like powder separator.

8 and 9 show a sixth embodiment, in which a short-circuit gas duct 47 is provided which penetrates the ceiling plate 31 of the pocket section 26 and connects this pocket section 26 and the gas duct 7a on the gas discharge port side.

A damper 4 is installed in the middle of the short circuit gas duct 47.
8 is provided. With this configuration, a gas flow is generated that flows from the cylindrical body 28 of the powder separator to the short pipe 34, the pocket section 26, the short-circuit gas duct 47, and the outlet side gas duct 7a, so that the coarse powder is not transferred to the pocket section 26. Separation efficiency can be improved, and pressure loss in the cyclone-like powder separator can be reduced depending on the amount of short-circuited gas. At this time, the amount of short circuit gas is controlled to an appropriate amount by the damper 48.

Further, the short pipe 34 connecting the cyclone main body 25 of the fine particle classifier 19 and the pocket section 26 of the coarse particle classifier 20 is connected to the cylindrical body 32 of the pocket section 26 substantially tangentially or circumferentially. There is. Therefore, the exhaust gas becomes a swirling flow within the pocket portion 26 as well as within the cyclone body 25, and the gas is reversed upward within the inverted conical cylinder 33. Therefore, the amount of the powder raw material that escapes from the pocket portion 26 to the gas duct 7a on the gas outlet side due to the short-circuiting gas discharged through the short-circuiting gas duct 47 can be suppressed to a minimum.

FIG. 10 shows a seventh embodiment, in which a powder separator C' ₁₃ at the second stage from the bottom in the exhaust gas system preheating device 3 and a powder separator C' ₂₃ at the second stage from the bottom in the combustion gas system preheating device 4 are used as classifiers, each consisting of a fine classifier 19 and a coarse classifier 20.
The fine grain discharge port 21 of the fine grain classifier 19 of the powder separator C' ₁₃ is connected to the calciner 8 through the raw material chute 15, and the coarse grain discharge port 22 of the coarse grain classifier 20 is connected to the calciner 8 through the raw material chute 15. It is connected to the gas inlet side gas duct 7a of the lower stage powder separator _C14 by a raw material chute 50. Further, the powder discharge port of the powder separator C ₁₄ is connected to the middle part of the raw material chute 15 from the fine grain discharge port 21 of the fine grain classifier 19 of the powder separator C' ₁₃ by another raw material chute 51 .

On the other hand, to explain the powder separator C' ₂₃ , the fine particle discharge port 21 of the fine particle classifier 19 is connected to the calciner 8 through the raw material chute 13, and the coarse particle discharge port 21 of the coarse particle classifier 20 is The discharge port 22 is connected to the gas duct 7a on the gas inlet side of the powder separator _C14 of the exhaust gas system preheating device 3 via a raw material chute 53. Therefore, the powdered raw materials input from the raw material supply ports 16, 16 of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 are transferred to the powder separators C' ₁₃ and C in the second stage from the bottom of each system preheating device. ' ₂₃ , it is classified into fine powder and coarse powder.

The fine powder is directly fed into the calciner 8, while the coarse powder is fed into the exhaust gas system preheating device 3.
The powder is fed into the calciner 8 of the combustion gas system preheating device 4 via the powder separator C ₁₄ at the lowest stage. On this occasion,
By adjusting the amount of coarse powder fed from the preheating devices of both systems to the calciner 8 via the powder separator C ₁₄ through the raw material chute 50, 53, the balance of thermal work in the preheating devices 3, 4 of both systems can be maintained. can be achieved. Further, the coarse classifier 20 of the powder separator C' ₁₃ in the exhaust gas system preheating device 3 and the coarse classifier 2 of the powder separator C' ₂₃ in the combustion gas system preheating device 4
The coarse powder from 0 joins in the gas duct 7a on the gas inlet side of the powder separator _C14 , and preliminary calcination of the coarse powder is performed in this duct 7a. Next, this coarse powder and the fine powder from the fine classifiers 19, 19 of the powder separators C' ₁₃ and C' ₂₃ are both highly calcined in the calcining furnace 8. Therefore, fine powder that is not easily collected passes only through the lowest powder separator C _{24 of the combustion gas system preheating device 4 without passing through the lowest powder separator C 14 of} the exhaust gas system preheating device 3. Therefore, the amount of circulation to the powder separator in the upper stage of the exhaust gas system preheating device 3 becomes small.

FIG. 11 shows the eighth embodiment, in which the powder separator C' ₁₃ is the second stage from the bottom in the exhaust gas system preheating device 3.
and the powder separator C' ₂₄ at the lowest stage in the combustion gas system preheating device 4 are used as classifiers, each of which is composed of a fine classifier 19 and a coarse classifier 20.

The fine grain discharge port 21 of the fine grain classifier 19 of the powder separator C' ₂₄ is connected to the firing furnace 1 through a raw material chute 23, and the coarse grain discharge port 22 of the coarse grain classifier 20 is connected to the raw material chute 18. It is connected to the gas inlet side gas duct 7a of the powder separator _C14 of the exhaust gas system preheating device 3. Meanwhile, the above powder separator C′ ₁₃
The fine particle discharge port 21 of the fine particle classifier 19 is connected to the coarse particle classifier 2 of the powder separator C' ₂₄ through the raw material chute 50.
0, and the coarse particle discharge port 22 of the coarse particle classifier 20 is connected to the combustion gas system preheating device 4 through the raw material chute 15.
It is connected to the calcining furnace 8.

Further, another calciner 55 is interposed between the gas inlet side gas duct 7a of the powder separator _C14 and the coarse particle outlet ₂₂ of the coarse particle classifier 20 of the powder separator C'24. An exhaust air duct 56 for supplying exhaust air from the cooling device 2 as needed is connected to the calciner 55, and an independent fuel supply device 57 is provided in the calciner 55.

Then, the fine powder in the powder raw material inputted from the raw material supply ports 16, 16 of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 is classified into fine particles in the powder separator C' ₁₃ in the exhaust gas system preheating device 3. machine 19,
It flows through the calcining furnace 55, the powder separator _C14 , and the calcining furnace 1, and in the combustion gas system preheating device 4, the powder separator _C23 , the calcining furnace 8, the fine particle classifier 19 of the powder separator _C'24 , and the calcining Flows with furnace 1. In addition, the coarse powder is transferred to the coarse classifier 20 of the powder separator C' ₁₃ and the powder separator
C ₂₃ is discharged to the calcination furnace 1 via the calcination furnace 8, the coarse classifier 20 of the powder separator C' ₂₄ , another calcination furnace 55, and the powder separator _C14 .

Therefore, the fine powder in the powder raw material input from the raw material supply port 16 of the exhaust gas system preheating device 3 is highly calcined while passing only through the calcination furnace 55 at the lowest stage of the exhaust gas system preheating device 3. At the same time, the fine powder in the powder raw material fed from the raw material supply port 16 of the combustion gas system preheating device 4 is highly calcined while passing only through the calciner 8 at the lowest stage of the combustion gas system preheating device 4. Baking is achieved. Further, the coarse powder in the powder raw materials preheated by the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 was partially calcined in the lowermost calcining furnace 8 of the combustion gas system preheating device 4. After that, the lowermost calcination furnace 55 of the exhaust gas system preheating device 3
A high degree of calcination is achieved.

In this embodiment, a large amount of thermal work can be taken at the lowest stage of the exhaust gas system preheating device 3, but depending on the degree of distribution of the thermal work, the powder separator C ₁₄ may be used instead of providing the calciner 55. It is sufficient to simply attach a fuel supply device to the gas inlet side gas duct 7a.
Further, the same effect as in the above embodiment can be obtained even if the combustion air in the gas inlet side gas duct 7a of the powder separator _C14 is supplied from the cooling device 2 through the firing furnace 1 instead of the exhaust air duct 56. I can do it.

FIG. 12 shows a ninth embodiment, in which the powder separator C' ₁₃ at the second stage from the bottom in the exhaust gas system preheating device 3 is used as a classifier, and a fine classifier 19 and a coarse classifier 20 are used.
It consists of The fine grain discharge port 21 of the fine grain classifier 19 is connected to the powder separator C ₁₄ by the raw material chute 50.
The coarse grain discharge port 22 of the coarse grain classifier 20 is connected to the calciner 8 through the raw material chute 15.

Then, the raw material supply port 1 of the exhaust gas system preheating device 3
The powder raw material input from 6 is classified into fine powder and coarse powder by powder separator C' ₁₃ , and the fine powder is transferred to the powder separator which is the lowest stage of the exhaust gas system preheating device 3.
It passes only through the gas duct 7 on the gas inlet side of C ₁₄ and is discharged into the firing furnace 1. The coarse powder is supplied from the coarse classifier 20 to the calciner 8, and from the calciner 8, it is discharged to the calciner 1 through powder separators _C24 and _C14 .

Therefore, the fine powder can be calcined to a high degree simply by passing through the gas duct 7a on the gas inlet side of the powder separator _C14 of the exhaust gas system preheating device 3.
Further, the above-mentioned coarse powder is partially calcined in the calcining furnace 8 together with the powder raw material input from the raw material supply port 16 of the combustion gas system preheating device 4, and then the powder separator
In the _C14 gas inlet side gas duct 7a, a high degree of calcination is achieved together with the fine powder.

Incidentally, the passage order of the coarse powder in the powder raw material that passes through multiple systems in series is the lowest heat exchange stage of the combustion gas system preheating device 4 as in the first, eighth, and ninth embodiments. The order may be from the lowest heat exchange stage of the exhaust gas system preheating device 3 to the lowest heat exchange stage of the exhaust gas system preheating device 3, or as in the seventh embodiment, the order may be from the lowest heat exchange stage of the exhaust gas system preheating device 3 to the highest heat exchange stage of the combustion gas system preheating device 4. The order of the lower heat exchange stage can be freely selected. Further, if necessary, the fine powder and the coarse powder can be combined in a raw material chute, mixed in advance, and then introduced into the firing furnace 1.

In the above explanation, the number of preheating devices that make up each system of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4, the type and number of stages of the powder separators that make up each preheating device, and even coarse powder and The type of powder separator for separating fine powder and the like is not limited to the above embodiment.

(Effects of the Invention) According to the present invention, the powder separator located at the lower part of at least one of the preheating devices consisting of the exhaust gas system preheating device and the combustion gas system preheating device is used to separate powder raw materials into fine powder and coarse powder. In addition to being a classifier for classifying into granular powder, the fine powder in the powder raw material passes through the lowermost powder separator of one preheating device, and
The fine particle discharge port and the coarse particle discharge port of the classifier were respectively connected to the path of each preheating device so that the coarse powder passed through the lowest stage powder separator of each preheating device in series. passes through the lowermost heat exchange stage of one preheating device and enters the kiln. Therefore, the above-mentioned fine powder is prevented from circulating in other preheating devices, and an increase in pressure loss and recarbonation in this preheating device can be prevented, and these exhaust gas system preheating devices and The operational efficiency of a multi-system preheating device consisting of a combustion gas system preheating device can be improved.

In addition, coarse powder, which requires a long residence time for calcination, passes in series through the lowermost heat exchange stage of both the exhaust gas system preheater and the combustion gas system preheater. During the passage, a high degree of calcination of the coarse powder can be achieved.

[Brief explanation of drawings]

Figures 1 to 12 show embodiments of the present invention, Figures 1 to 3 are the first embodiment, Figure 1 is a system diagram of a cement raw material firing device, and Figure 2 is a classifier. A side view of the powder separator, FIG. 3 is a partially cutaway plan view taken in the direction of the - arrow in FIG. 2, FIG. 4 is a view corresponding to the broken part in FIG. 3, and FIG. is a diagram corresponding to FIG. 3 of the third embodiment, and FIG. 6 is a diagram corresponding to FIG.
The figure shows the fourth embodiment and corresponds to FIG. 2, FIG. 7 shows the fifth embodiment and corresponds to FIG. 2, and FIGS. 8 and 9 show the sixth embodiment and FIG. FIG. 9 is a diagram corresponding to FIG. 3, FIG. 10 is a diagram corresponding to FIG. 1 in the seventh embodiment, and FIG. 11 is a diagram corresponding to FIG.
A diagram corresponding to FIG. 1 in the example, and FIG. 12 is a diagram corresponding to FIG. 9.
FIG. 13 is a diagram corresponding to FIG. 1 in the embodiment, and FIG. 13 is a diagram corresponding to FIG. 1 in the conventional example. 1... Firing furnace, 2... Cooling device, 3... Exhaust gas system preheating device, 4... Combustion gas system preheating device, 7
a... Gas duct, 8... Calciner, 10... Fuel supply device, 13... Raw material chute, 14... Raw material chute, 15... Raw material chute, 18... Raw material chute, 19... Fine particle classifier , 20... Coarse particle classifier, 21... Fine particle discharge port, 22... Coarse particle discharge port, 23... Raw material chute, 25... Cyclone body, 26... Pocket portion, 50... Raw material chute, 51 ... Raw material chute, 53 ... Raw material chute, 55 ... Calciner, 57 ... Fuel supply device,
C ₁₁ ~ C ₁₄ , C ₂₁ ~ _{C 24} ... Powder separator, C' ₁₃ , C' ₂₃ ,
C′ ₂₄ ...Powder separator.

Claims (1)

[Claims] 1. A firing furnace for firing the powder raw material, a cooling device for cooling the fired product discharged from the firing furnace with an air flow, and an exhaust gas system preheating system for preheating the powder raw material with the exhaust gas from the firing furnace. and a combustion gas system preheating device that burns fuel using the exhaust air from the cooling device and preheats the powder raw material with the combustion gas, and each of the preheating devices are stacked vertically and connected to each other. each of a plurality of powder separator groups arranged in the combustion gas system, the powder discharge port of the lowest stage powder separator of at least one preheating device is connected to the firing furnace; A calciner is installed between the gas inlet of a powder separator and the powder outlet of another powder separator above this powder separator to preheat the powder raw material by burning fuel using exhaust air from the cooling device. In the interposed powder raw material firing apparatus, the powder separator located at the bottom of at least one of the preheating devices is used as a classifier for classifying the powder raw material into fine powder and coarse powder. The fine particles in the classifier are separated so that the fine powder in the classifier passes through the bottom powder separator of one preheating device, and the coarse powder passes through the bottom powder separator of each preheating device in series. A multi-system powder raw material preheating device characterized in that a discharge port and a coarse particle discharge port are respectively connected to the paths of each preheating device. 2. The classifier is characterized in that it is composed of a cyclone-like fine-grain classifier and a pocket-shaped coarse-grain classifier formed outside the fine-grain classifier and communicating with the inner wall surface of the fine-grain classifier. A multi-system type powder raw material preheating device according to claim 1. 3. Claim 1 or 2, characterized in that a calciner equipped with an independent fuel supply device is provided on the gas inlet side of the powder separator at the lowest stage of the exhaust gas system preheating device. Multi-system type powder raw material preheating device.