JPH0424629B2 - - 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 various configurations, including an exhaust gas system preheating device that mainly uses exhaust gas from a firing furnace, and a preheating device that uses high temperature exhaust air from a cooling device for fired products. Some systems have a combustion gas system preheating device and a combustion gas system preheating device that mainly uses the combustion gas generated by burning fuel in a calcining furnace.

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 above-mentioned calcination method, the combustion gas system preheating device allows the powder raw material to be highly calcined by adjusting the amount of fuel supplied.
In the exhaust gas system preheating device, the exhaust gas from the kiln, which is introduced at a temperature of about 1000 to 1100℃, is inside the preheating device.
The amount of heat that can be used for calcination of the powder raw material during the temperature drop to about 850 to 950°C is the Due to insufficient heat compared to the amount of heat available for preheating the raw materials, it is not possible to increase the calcination rate of the powder raw materials discharged from the exhaust gas system preheating device to the kiln, or to the extent that calcination is possible to a high degree. If the amount of powdered raw material supplied to the exhaust gas system preheating device is limited, there will be a surplus of heat available for preheating, which will increase the temperature of the gas discharged from the preheating device. In order to eliminate these inconveniences, it has been conventional practice to supply a portion of the powdered raw material that passes through the lower part of the exhaust gas system preheating device to the calciner of the combustion gas system or to the gas duct near the calciner. ing.

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, and high-temperature exhaust air from the cooling device 2 is sent into the firing furnace 1 for fuel combustion in the firing furnace 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 in the vertical direction, 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. Further, the inlet cover 5 of the firing furnace 1 and the gas inlet of the powder separator C ₁₄ at the lowest stage are also connected by a gas duct 7a. Furthermore, the gas outlet of the powder separator C ₁₁ on the top stage is connected to the exhaust gas fan 1.
2a through a gas duct 7c.

The gas inlet of each powder separator is connected to the powder outlet of another powder separator above this powder separator by a raw material chute 13, respectively. Also,
The gas duct 7a on the gas inlet side of the powder separator _C11 at the top stage is provided with a raw material supply port 16 into which powdered raw material is introduced.

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, 7c and a raw material chute 13. In addition, in this combustion gas system preheating device 4, a gas duct 7b on the gas inlet side of the powder separator C ₂₄ at the lowest stage and the powder discharge port of the powder separator C ₂₃ located above this powder separator C ₂₄ are connected. A calciner 8 is provided which uses exhaust air from the cooling device 2 to combust fuel and preheat the powder raw material. 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 powder separator C ₂₄ at the lowest stage of the combustion gas system preheating device 4 is connected to the inlet cover 5 of the firing furnace 1 by a raw material chute 14b, and the powder separator C 24 at the lowest stage of the exhaust gas system preheating device 3 is connected to the inlet cover 5 of the firing furnace 1. The powder discharge port of the vessel C ₁₄ is connected to the middle part of the raw material chute 14b from the powder discharge port of the powder separator C ₂₄ by a raw material chute 14a.

Furthermore, the middle part of the raw material chute 13 from the powder discharge port of the powder separator C ₁₃ in the second stage from the bottom in the exhaust gas system preheating device 3 is connected to the powder separator C in the second stage from the bottom in the combustion gas system preheating device 4. A branch chute 15 connects to the middle part of the raw material chute 13 from the powder discharge port ₂₃ .

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 powdered raw materials inputted from each of the raw material supply ports 16, 16 are heated by the high-temperature gas and passed through the powder separator C ₁₁ at the top stage of each preheating device 3, 4.
It flows from C ₂₁ toward the lower stage, is fired in the firing furnace 1 to become clinker, is cooled in the cooling device 2, and is transferred to the next process (in the figure, the flow of the powder raw material is indicated by the broken line arrow).

In the above case, a part of the preheated powder raw material discharged from the powder separator C ₁₃ at the second stage from the bottom in the exhaust gas system preheating device 3 is transferred to the combustion gas system preheating device 4.
It is branched and supplied to the calcining furnace 8. Therefore, the quantitative ratio of the powder raw material inputted from the powder separator C ₁₃ to the gas inlet side gas duct 7b of the lowest stage powder separator C ₁₄ is reduced. Therefore, the powder raw material supplied from the lowest stage powder separator C ₁₄ in the exhaust gas system preheating device 3 to the firing furnace 1 is highly calcined while flowing through the gas duct 7a. In addition, in the combustion gas system preheating device 4, the powder raw material can be highly calcined by adjusting the fuel supplied from the fuel supply device 10 into the calcining furnace 8.

(Problems to be Solved by the Invention) Incidentally, in a preheating device comprising a plurality of systems as described above, the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 are originally arranged independently for each device. be. For this reason, the branch chute 1 communicates the powder separator C ₁₃ at the second stage from the bottom of the exhaust gas system preheating device 3 with the calciner 8 of the combustion gas system preheating device 4.
A horizontal distance of 5 requires relatively large dimensions.
In particular, when the combustion gas system preheating device 4 is additionally installed to the existing exhaust gas system preheating device 3, the horizontal distance of the branch chute 15 is large.

In this case, in order to prevent the powder raw materials from accumulating in the branching chute 15, it is necessary to set the inclination angle with respect to the horizontal plane to a certain degree, for example, 50 to 55 degrees or more. A large vertical distance is required between both devices. However, if such a large vertical distance is attempted, the overall size of the device increases. Furthermore, even when another preheating device is newly installed, there is a problem in that the arrangement of each powder separator and calciner is severely restricted due to the necessity of ensuring a predetermined angle for the branch chute 15.

Furthermore, by additionally installing the combustion gas system preheating device 4 to the existing exhaust gas system preheating device 3, the capacity of the entire firing device can be increased, for example, by up to about 2.5 times. When carrying out such modification work, it may also be attempted to reduce the pressure loss of the existing exhaust gas system preheating device 3 and reduce the driving force of the exhaust gas fan 12a to save energy.

However, the amount of exhaust gas introduced from the firing furnace 1 to the exhaust gas system preheating device 3 is mainly determined by the temperature and degree of calcination of the powder raw material supplied to the firing furnace 1 from the preheating devices 3 and 4 of both systems. It is a thing,
The amounts of gas passing through the preheating devices of both systems are not mutually adjusted. Therefore, when determining the degree of capacity increase due to the above modification, the amount of gas introduced from the firing furnace 1 to the existing exhaust gas system preheating device 3 is determined, and along with this, the pressure loss in the exhaust gas system preheating device 3 is determined. is determined. Therefore, if you try to increase the capacity of the preheating device as a whole, there is a risk that the pressure loss in the exhaust gas system preheating device 3 will increase, and conversely, if you try to reduce the pressure loss, you will have to limit the increase in capacity. I was in an unprecedented situation.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and it connects the proper location of the exhaust gas system preheating device and the proper location of the combustion gas system preheating device, and connects one of these devices to the other. When conveying the powder raw material to the connecting part, the structure is designed to prevent the powder raw material from accumulating at this connection part, and the overall size of the device is prevented, and the pressure loss of the exhaust gas passing through the exhaust gas system preheating device is minimized. The purpose is to reduce

(Structure of the Invention) In order to achieve the above object, the present invention is characterized in that the gas inlet side of the powder separator in the second stage from the bottom of the exhaust gas system preheating device is connected to the upper part of the combustion gas system preheating device. is connected to the passage through a powder separation means, and the powder discharge port of the powder separation means is connected to a lower passage of the combustion gas system preheating device,
The present invention is characterized in that an air volume adjusting means is provided for this powder separating means.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. The basic configuration of these embodiments is the same as that of the conventional example. Therefore, those having the same configuration are given the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a first embodiment.

Gas inlet side gas duct 7 of the second stage powder separator C ₁₃ from the bottom in the exhaust gas system preheating device 3
In a, after the powder raw material supplied through the raw material chute 13 from the powder discharge port of the powder separator C ₁₂ in the third stage from the bottom is dispersed in the hot gas rising in the gas duct 7a, a part of the powder raw material is The gas duct 7a is connected to the powder separator C ₂₂ at the third stage from the bottom of the combustion gas system preheating device 4 through the connecting duct 18 so that the powder separator C 22 is distributed and supplied to the combustion gas system preheating device 4 side together with the hot gas. .

An inertial powder separator C ₀₁ serving as powder separation means is interposed in the middle of the connecting duct 18 . The powder discharge port of this inertial powder separator C ₀₁ is connected to the middle part of the raw material chute 13 from the powder discharge port of the second stage powder separator C ₂₃ from the bottom of the combustion gas system preheating device 4 via the raw material chute 19. Ru. In addition, in the connecting duct 18 on the gas outlet side of the inertial powder separator C ₀₁ ,
A damper 20 is provided as an air volume adjusting means for opening and closing the connecting duct 18. Furthermore, a damper 21 is provided in the air duct 9 leading to the calciner 8 of the combustion gas system preheating device 4 .

Then, the raw material supply port 1 of the exhaust gas system preheating device 3
The powder raw material input from 6 is branched and supplied to the powder separator C ₁₃ and the inertial powder separator C ₀₁ together with the gas, and is separated into the gas and the powder raw material in the inertial powder separator C ₀₁ . It is put into the calcining furnace 8 of the combustion gas system preheating device 4. Furthermore, the exhaust gas from the inertial powder separator C ₀₁ passes through the damper 20 and is introduced into the powder separator C ₂₂ .

The amount of hot gas and powder raw material branched and distributed from the exhaust gas system preheating device 3 to the combustion gas system preheating device 4 in this way is suitably 10 to 40% of the amount of each introduced into the exhaust gas system preheating device 3. be. These branched amounts are adjusted by the damper 20 provided in the connecting duct 18 in accordance with the temperature equilibrium state in both systems.

FIG. 2 shows a second embodiment of the exhaust gas system preheating device 3.
The combustion gas system preheating device 4 has five stages of powder separator groups C ₁₀ to C ₁₄ and C ₂₀ to C ₂₄ stacked vertically, respectively.

The powder separation means installed in the connecting duct 18 connecting the exhaust gas system preheating device 3 and the combustion gas system preheating device 4 is a cyclone powder separator C ₀₂ , and the gas discharge port of this cyclone powder separator C ₀₂ is is connected to the gas inlet side gas duct 7a of the fourth powder separator _C21 from the bottom of the combustion gas system preheating device 4 by a connecting duct 18. In addition, the powder discharge port of this cyclone powder separator C ₀₂ is connected to the raw material chute 23 to the gas inlet side gas duct 7a of the second stage powder separator C ₂₃ from the bottom of the combustion gas system preheating device 4.
Connected by

Furthermore, an independent fuel supply device 24 is provided on the gas inlet side gas duct 7b of the powder separator C ₁₄ at the lowest stage of the exhaust gas system preheating device 3.

Therefore, the powder raw material branched from the gas duct 7a at the second stage from the bottom of the exhaust gas system preheating device 3 and supplied to the cyclone powder separator C ₀₂ along with the gas is separated from the gas in this powder separator C ₀₂ before being separated from the gas. It is discharged to the gas duct 7a on the gas inlet side of the powder separator C ₂₃ , and is fed to the raw material supply port 1 of the combustion gas system preheating device 4.
Powder separator C ₂₃ with powder raw material input from 6
It is supplied to the calcining furnace 8 via. Then, a high degree of calcination is achieved in the calcination furnace 8.

Further, the powder raw material input from the powder separator C ₁₃ in the second stage from the bottom of the exhaust gas system preheating device 3 to the gas inlet side gas duct 7b of the powder separator C ₁₄ in the lowest stage rises in the gas duct 7b. Firing furnace 1
By supplying fuel as necessary from the fuel supply device 24 into the exhaust gas from the fuel and combusting it, further calcining is achieved. After being calcined in this manner, it is discharged to the firing furnace 1 together with the calcining raw material in the combustion gas system preheating device 4.

Note that when the fuel supply device 24 is installed in the gas inlet side gas duct 7b of the lowermost powder separator C ₁₄ of the exhaust gas system preheating device 3, the gas duct 7b may be configured in the shape of a calciner. Similar to the calcining furnace 8 of the combustion gas system preheating device 4, it may be connected to the cooling device 2 through an air duct 9.

In addition, the number of preheating devices constituting each system of the exhaust gas system preheating device 3 and the combustion gas system preheating device 4, the type of powder separation means installed in the connecting duct 18, and the powder separator constituting each preheating device are also determined. The type, number of stages, type of calcining furnace, etc. are not limited to those in each of the above embodiments.

(Effects of the Invention) According to the present invention, the gas inlet side of the powder separator in the second stage from the bottom of the exhaust gas system preheating device is connected to the upper path of the combustion gas system preheating device via the powder separation means. At the same time, because the powder discharge port of this powder separation means is connected to the path at the bottom of the combustion gas system preheating device, a part of the powder raw material input into the exhaust gas system preheating device is once separated into powder by the flow of exhaust gas from the kiln. The powder raw material and the gas separated therein are respectively supplied to appropriate locations in the combustion gas system preheating device. In other words, since the powder raw material is transported from the exhaust gas system preheating device side to the powder separation means by the flow of exhaust gas, even if the horizontal distance from the exhaust gas system preheating device side to the powder separation device is sufficiently large, there will be a This prevents the operation from being hindered by the accumulation of powder raw materials. Therefore, if necessary, the powder separating means is placed near the combustion gas system preheating device by a sufficient horizontal distance from the exhaust gas system preheating device, and the powder discharge port of the powder separating means is connected to the combustion gas system preheating device. It can be connected at large angles of inclination as required in the lower channel of the system preheating device. Therefore, the powder raw material is prevented from accumulating even in this path. As a result, when the exhaust gas system preheating device and the combustion gas system preheating device are connected, powder raw materials are prevented from accumulating in this connection. Moreover, in this case, since there is no need for a large height difference between the exhaust gas system preheating device and the combustion gas system preheating device, it is possible to prevent these devices from increasing in size as a whole.

Moreover, in order to transport a portion of the powdered raw material input into the exhaust gas system preheating device to the combustion gas system preheating device, the amount of heat that can be used for preheating is surplus compared to the amount of heat that can be used for calcination of the powdered raw material as described above. This system is designed to use a part of the firing furnace exhaust gas, which is supplied to the calcining area by a part of the hot gas discharged from the lowermost calcining area in the exhaust gas system preheating device and flowing to the upper preheating area. The powder is extracted from the exhaust gas system preheating device via the powder separation means to the combustion gas system preheating device, accompanied by the preheated raw material just before being processed.

At this time, since an air volume adjustment means is provided for the powder separation means, the air volume adjustment means moves the exhaust gas system preheater from the combustion gas system to the exhaust gas system preheater in accordance with the temperature equilibrium state of the exhaust gas system preheater and the combustion gas system preheater. The amount of hot gas and powder raw material branched to the preheating device can be adjusted.
Therefore, both preheating devices can achieve a high degree of calcination of the powder raw material, and the amount of heat required for calcination and preheating in both preheating devices can be balanced.

In addition, as the hot gas moves from the exhaust gas system preheating device to the combustion gas system preheating device, the amount of exhaust gas passing through the upper part of the exhaust gas system preheating device decreases, resulting in a pressure loss in the upper part of the exhaust gas system preheating device. reduction is achieved.

In particular, when a combustion supply device is installed in the lowest stage gas duct of the exhaust gas system preheating device, the insufficient amount of heat for calcination in the exhaust gas system preheating device can be supplemented, so branch supply is supplied to the combustion gas system preheating device. It is necessary to reduce the amount of powder raw material and gas. That is, by adjusting the distribution of fuel supplied to both preheating devices, the amount of powder raw material and gas branched from the exhaust gas system preheating device to the combustion gas system preheating device, and therefore the amount of hot gas passing through the upper part of both preheating devices. As a result, the share of preheating and calcination work for the powder raw materials in both systems can be adjusted over a wide range, and economical equipment design and operation can be achieved. .

[Brief explanation of drawings]

1 and 2 show an embodiment of this invention,
Fig. 1 is a system diagram of a cement raw material firing device according to the first embodiment, Fig. 2 is a diagram corresponding to Fig. 1 according to the second embodiment, and Fig. 3 is a diagram corresponding to Fig. 1 according to 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, 7b...Gas duct, 8...
Calciner, 10... Fuel supply device, 13... Raw material chute, 14a... Raw material chute, 14b... Raw material chute, 18... Connection duct, 19... Raw material chute, 20... Damper, 23... Raw material Chute, 24...Fuel supply device, _C10 - _C14 ...Powder separator, _C20 - _C24 ...Powder separator, _C01 ...Inertial powder separator (powder separation means), _C02 ...Cyclone Powder separator (powder separation means).

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. The powder separator groups located at the lowest stage of each preheating device are connected to the firing furnace, and the powder separator groups located at the lowest stage of the combustion gas system preheating device are connected to the firing furnace. A calciner is provided between the gas inlet of the 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 powder raw material firing apparatus installed, the gas inlet side of the second stage powder separator from the bottom of the exhaust gas system preheating device is connected to the upper path of the combustion gas system preheating device via a powder separation means, and A multi-system powder raw material preheating device, characterized in that the powder discharge port of the powder separation device is connected to a lower passage of a combustion gas system preheating device, and an air volume adjustment device is provided for the powder separation device. 2. The multi-system powder raw material preheating device according to claim 1, characterized in that 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. 3. A multi-system powder raw material preheating device according to claim 1 or 2, characterized in that the powder separation means is a cyclone powder separator.