JPH06103152B2 - Method for improving thermal efficiency in kiln equipment and its equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to promoting combustion of a burner in a kiln device,
High temperature combustion gas in the rotary kiln and burned material, cooling air in the clinker cooler and burned material used for cooling, high temperature combustion gas in the kiln preheater and burned material and high temperature in the exhaust heat exchanger The present invention relates to a method for promoting heat transfer between exhaust gas and a heat exchanger to improve the thermal efficiency of a kiln device and an apparatus for implementing the same.

<Prior Art> In a kiln device for firing cement or dolomite, the raw material is preheated by a kiln preheater and then stirred in a rotary kiln while moving downward along a longitudinal inclination while A method of heating and firing with a high temperature combustion gas and then cooling with a clinker cooler is generally performed.

In this case, the raw material, that is, the material to be fired is inserted through the inlet of the rotary kiln after being preheated by the preheater, is stirred in the rotary kiln as described above, is moved in the longitudinal direction while being discharged to the clinker cooler while cooling in the longitudinal direction. To be done. On the other hand, the hot combustion gas generated by combustion by the burner provided on the outlet side of the rotary kiln, that is, hot air, flows toward the inlet side from the outlet of the object to be fired of the rotary kiln, that is, opposite to the moving direction of the object to be fired. It becomes convection in the direction and flows out. During this time, heat is transferred from the high-temperature combustion gas to the object to be fired in the rotary kiln, the object to be fired is heated and fired, and then cooled with cooling air in the clinker cooler.

<Problems to be Solved by the Invention> However, in the conventional kiln device, it takes a considerable time to perform sufficient heat transfer between the high-temperature combustion gas and the object to be fired and between the cooling air and the object to be fired. Therefore, there is a problem in that the rotary kiln must be made considerably long to increase the residence time in the rotary kiln of the object to be fired and also to lengthen the preheater and the clinker cooler.

<Means for Solving the Problem> Generally, the larger the relative velocity V (m / sec) between the gas and the solid, the more severe the turbulent flow of the gas, and the heat transfer coefficient K (kcal / kcal / k) between the gas and the solid. It is well known that m ² h ℃) increases. The present invention uses the above-mentioned heat transfer coefficient K (kcal / m ² h
As a means of increasing the temperature (° C), the high temperature combustion gas in the preheater and the high temperature combustion gas flowing from the outlet side to the inlet side of the rotary kiln are provided with low frequency sound waves with a frequency of about 50 Hz or less, so Improves heat transfer between the fired product and high-temperature fired product by giving low-frequency sound waves with a frequency of about 50Hz or less to the cooling air of the clinker cooler. Also, by giving a low-frequency sound wave with a frequency of about 50 Hz or less to the combustion air of the burner to burn it, complete combustion can be achieved with a small amount of excess air, so the temperature of the combustion gas can be raised. Therefore, an object of the present invention is to solve the above-mentioned problems by increasing the temperature difference between the high temperature combustion gas and the object to be fired to improve the heat transfer between the high temperature combustion gas and the object to be fired.

As a result, the combustion air of the burner needs only a small amount of excess air,
Moreover, a small amount of cooling air is needed for the clinker cooler. Since the low-frequency sound wave according to the present invention is applied as described above, the amount of air consumed by the entire kiln device can be reduced. Therefore, when the exhaust gas temperature is the same, the amount of heat exhausted to the atmosphere is reduced. In other words, there is an advantage that an energy saving effect can be obtained.

Furthermore, by applying low-frequency sound waves of about 50 Hz or less to the hot exhaust gas passing through the exhaust heat exchanger, heat transfer with the heat exchanger is promoted, and the temperature of the exhaust gas released to the atmosphere can be lowered. In addition, there is an advantage that an energy saving effect can be obtained.

As a means for giving a low frequency sound wave, for example, a low frequency sound wave generator disclosed in Japanese Patent Publication No. 58-55834; PCT / SE88 / 00172 AIR-DRIVEN LOW-FREQUENCY SOUND GENE
RATOR WITH POSITIVE FEEDBACK SYSTEM .; PCT / SE89 / 00367 LOW-FREQUENCY SOUND GENERATOR, ESPE
CIALLY FOR GRILLS. Other types of low frequency sound wave generator, such as reciprocating piston to generate low frequency sound wave by using rotational motion of motor or magnetic force, are not limited.

<Examples> Examples will be described below in more detail with reference to the drawings.

FIG. 1 shows a conceptual diagram of the process of the kiln device, in which the material to be fired 1 is preheated through a preheater 2 and sent into the rotary kiln 3 and moved in the longitudinal direction while being stirred in the rotary kiln 3. While rotating, the kiln 3 is heated and baked during this time.
It is sent to the clinker cooler 4 from the outlet part of, and is cooled to complete the firing process.

On the other hand, the high-temperature combustion gas generated by the burner 5 flows in the rotary kiln 3 in the direction opposite to the moving direction of the object to be fired 1 as convection, transferring heat to the object to be fired 1b and at the inlet of the rotary kiln 3. After passing through the preheater 2, the exhaust heat exchanger 6, the electrostatic precipitator 7, and the exhaust air blower 8 are exhausted to the atmosphere from the chimney 9.

In addition, the cooling air sent from the fan 11, the fan 12, the fan 13, ..., The fan 14 into the clinker cooler 4 cools the high temperature fired product 1c, and a part of the cooling air passes through the rotary kiln 3 and the chimney 9 as described above. More is discharged into the atmosphere, and the other part passes through the exhaust heat exchanger 15, the electrostatic precipitator 16, the exhaust blower 17, etc.
Emitted from 18 into the atmosphere.

According to the present invention, as described above, with respect to the flow velocity V ₁ (m / sec) of the high temperature combustion gas flowing in the rotary kiln 3, the low frequency sound wave generator 10 installed at the outlet side of the rotary kiln 3 produces a low frequency wave of about 50 Hz or less. by frequency sound waves vibration velocity V ₂ (m / sec) is given, the gas molecules of the hot combustion gases while oscillating in the the rotary kiln 3 sonic vibration speed _{± V 2 '(m / sec} ), the flow velocity V ₁
At (m / sec), it moves in the direction of the inlet of the rotary kiln 3 and heat is transferred to the object to be fired 1b during this time to perform firing.

Furthermore, a low-frequency sound wave generator is also applied to the hot combustion gas or hot exhaust gas flowing in the preheater 2, the exhaust heat exchangers 6 and 15, respectively.
Since low-frequency sound waves of about 50 Hz or less are applied at 19, 22 and 23, the sound waves pass while vibrating at the same sound wave vibration speed, so the heat transfer coefficient K of each device
(Kcal / m ² ℃) is improved.

Similarly, after firing is completed, the fired product 1c carried out to the clinker cooler 4 is loaded on a clinker bed 24 formed of a perforated plate and cooled by cooling air blown from below the clinker bed 24. The cooling air is oscillated at the same sound wave vibration speed as a low frequency sound wave of about 50 Hz or less is applied by the low frequency sound wave generator 20 and passes between the fired products 1c from the lower side to the upper side to cool. To do.

FIG. 2 is a model diagram showing a difference in loci of motions of gas molecules between the high temperature combustion gas flowing in the rotary kiln 3 according to the conventional method and the high temperature combustion gas when the low frequency sound wave of the present invention is applied.

When the turbulence of the gas flow due to the contact between the material to be fired 1b and the high temperature combustion gas is neglected, if the length of the rotary kiln 3 is L (m), in the conventional method, in the rotary kiln 3 of arbitrary gas molecules, The length of the locus of motion is La (m), which indicates that La = L.

Therefore, the transit time t of any gas molecule in the rotary kiln is
(Sec) is Becomes

In the present invention, the length of the locus of motion of any gas molecule in the rotary kiln 3 is Lb (m), and Lb> La = L.

The amplitude of the low frequency sound wave is δ (m).

Therefore, the length of the locus of motion in which an arbitrary gas molecule comes into contact with the object to be fired becomes Lb / La times when a low-frequency sound wave is applied. In other words, the average relative flow velocity is Lb / La times.

This means that the relative flow velocity between the gas and the solid becomes Lb / La times by applying the low frequency sound wave according to the present invention, as described above, and the heat transfer coefficient K (kcal / m ² h between the gas and the solid). ℃)
Will increase.

Therefore, as described above, by applying low-frequency sound waves to the high temperature combustion gas in the rotary kiln 3, it is possible to increase the calcining amount of the kiln equipment, save fuel, that is, save energy, or increase the length of the rotary kiln 3. It is possible to make profits by shortening the length and reducing the equipment cost.

FIG. 3 is an explanatory diagram of the cooling state of the fired product 1c in the clinker cooler 4. That is, FIG. 3A shows the structure of the clinker bed 24, the state of the fired product 1c loaded on the clinker bed 24, and the manner in which cooling air flows between them.

FIG. 3b is a model diagram showing the difference in the loci of the motions of the gas molecules of the cooling air flowing in the fired product 1c by the conventional method and the cooling air according to the present invention when the low frequency sound waves are applied.

Similar to the description of FIG. 2, the following relationship is established in the locus of motion of the cooling air flowing between the fired products 1c.

L ′ = L′ a <L′ b That is, the length of the locus of the movement of an arbitrary gas molecule in contact with the fired product 1c is L′ b / L′ a by applying a low frequency sound wave.
It shows that the average relative flow velocity becomes L'b / L'a times, and the heat transfer coefficient K (kcal / m ² h
C) will increase.

Therefore, as described above, by applying low-frequency sound waves to the cooling air in the clinker cooler 4, the cooling capacity of the clinker cooler 4 is increased, or the length of the clinker cooler 4 is shortened to reduce the equipment cost. Can be profitable. Then, the amount of cooling air used can be reduced. This contributes to improving the thermal efficiency of the entire kiln device.

Similarly, in FIG. 4, as an example of an exhaust heat exchanger, in the case of a heat exchanger using a heat exchange pipe 25, the state of circulation of high-temperature exhaust gas (FIG. 4a) and the movement of arbitrary gas molecules are shown. A model of the locus (Fig. 4b) is shown.

Similar to the above description, L ″ = L ″ a <L ″ b holds, that is, by applying a low frequency sound wave, the average relative speed becomes L ″ b / L ″ a times, and the high temperature inside the exhaust heat exchanger becomes high. Heat transfer coefficient K between exhaust gas and heat exchange pipe 25 (kcal / m ² h
C.) can be increased, and the heat exchange capacity of the exhaust heat exchanger can be increased.

FIG. 5 shows a burner 5 equipped with a dedicated low-frequency sound wave generator 21 in addition to the low-frequency sound wave generator 10 to burn under optimum combustion conditions and reduce excess air to obtain high-temperature combustion gas. Is.

FIG. 6 shows the details of the mounting example of the low frequency sound generator 10 for the rotary kiln 3 which also serves as the low frequency sound generator for the burner. The low frequency sound is generated between the burned material 1b and the high temperature combustion gas. In addition to improving the heat transfer to and from, the burner 5 also has the effect of promoting combustion.

FIG. 6a is an example of a mounting method that effectively utilizes both of the above effects.

However, in such a case, the capacity and other detailed conditions of the low-frequency sound wave generator 10 that are optimal for improving heat transfer in the rotary kiln 3 generally do not necessarily match the optimal conditions of the combustion conditions of the burner 5, Naturally, the method of FIG. 5 is superior in terms of capability. However, the method of FIG. 6 has an advantage that the equipment cost is low.

If it is desired to reduce the influence of low-frequency sound waves on the burner depending on the type of burner, the low-frequency sound wave generator 10 may be hung and mounted from above on a hanger 19 as shown in FIG. 6b. is there. That is, the low frequency sound wave generator 10
The object of the present invention can be achieved as long as the mounting position is near the outlet of the rotary kiln 3.

FIG. 7 shows the high temperature combustion gas in the rotary kiln 3 and the object to be fired 1b.
1 shows an example in which a low frequency sound wave generator 21 for a burner is provided without providing a low frequency sound wave generator 10 for promoting heat transfer between them.

The low-frequency sound wave generator 21 for the burner also has the effect of promoting heat transfer between the high-temperature combustion gas and the article to be fired 1b, as in the case where the low-frequency sound wave generator 10 is provided. The method (1) is superior to the method shown in FIG.

Whether the method shown in FIG. 5, the method shown in FIG. 6 or the method shown in FIG. 7 is adopted depends on the heat transfer promoting effect required between the high temperature combustion gas in the rotary kiln 3 and the object to be fired 1b and The equipment configuration is determined by comprehensively considering the combustion efficiency of the burner 5, the equipment cost, and the like.

<Effects of the Invention> As described above, the present invention provides the high temperature combustion gas in the preheater,
The high-temperature combustion gas supplied to the rotary kiln, the cooling air in the clinker cooler, and the high-temperature exhaust gas in the exhaust heat exchanger were each provided with low-frequency sound waves of about 50 Hz or less. And, the high temperature exhaust gas has a significantly high local moving speed of flowing gas molecules, which increases the heat transfer coefficient between each gas and the solid in contact with them, and therefore, the ability of preheating, firing and cooling at the same time. The combustion efficiency of the burner is improved by applying low-frequency sound waves of about 50 Hz or less to the combustion air and fuel particles of the burner, reducing the fuel consumption of the entire kiln device and achieving the same effect. This has the effect of promoting energy saving.

In addition, the improvement of the thermal efficiency makes it possible to downsize the preheater, the rotary kiln, the clinker cooler, and the exhaust heat exchanger, thereby reducing the facility cost and keeping the facility space small.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the process of the kiln device, FIG. 2 is a model diagram showing the trajectories of gas molecules when a low frequency sound wave is applied according to the conventional method and the present invention, and FIG. 3a is a partially enlarged sectional view of a clinker cooler. Fig. 3b is a model diagram showing the difference in the trajectory of the movement of gas molecules, Fig. 4a is a partially enlarged sectional view of the exhaust heat exchanger, and Fig. 4b is the trajectory of the movement of gas molecules. Fig. 5 is a model diagram showing the difference, Fig. 5 is an enlarged view of the rotary kiln outlet side portion in Fig. 1, and Fig. 6a is a partially enlarged view showing an example of mounting a low frequency sound wave generator of a rotary kiln that also serves as a burner, FIG. 6b is another mounting example, and FIG. 7 is a partially enlarged view showing an example in which only a low frequency sound wave generator for burner is mounted.
1a, 1b, 1c and 1d are objects to be fired, 2 is a preheater, 3 is a rotary kiln, 4 is a clinker cooler, 5 is a burner, 6 is an exhaust heat exchanger, 7 is an electrostatic precipitator, 8 is an exhaust air blower, 9 Is a chimney, 10 is a low-frequency sound generator for a rotary kiln, 11, 12, 13, 1
4 is a cooling fan, 15 is an exhaust heat exchanger, 16 is an electrostatic precipitator, 17 is an exhaust blower, 18 is a chimney, 19 is a low frequency sound generator for the preheater, and 20 is a low frequency for the clinker cooler. A sound wave generator, 21 is a low frequency sound wave generator for the burner, 22 and 23 are low frequency sound wave generators for the exhaust heat exchanger, 24 is a clinker bed, and 25 is a heat exchange pipe.

Claims (12)

[Claims] 1. A kiln device for heating and burning a material to be fired in a rotary kiln with a high temperature combustion gas, wherein a low frequency sound wave of about 50 Hz or less is applied to the high temperature combustion gas to cause a gap between the high temperature combustion gas and the object to be fired. A method for promoting firing in a rotary kiln in a kiln device, characterized by promoting heat transfer. 2. A heat transfer between the cooling air and the high temperature calcined material is promoted by applying a low frequency sound wave of about 50 Hz or less to the cooling air supplied to the clinker cooler connected to the outlet side of the rotary kiln. A method for promoting cooling of a clinker cooler in a characteristic kiln device. 3. Heat transfer between the high temperature combustion gas and a preheat-dried object by applying a low frequency sound wave of about 50 Hz or less to the high temperature combustion gas flowing in the preheater provided near the inlet side of the rotary kiln. A method for promoting heat transfer in a preheater of a kiln device, which is characterized by promoting heat transfer. 4. A low-frequency sound wave of about 50 Hz or less is applied to combustion air and fuel particles supplied to a burner of a rotary kiln,
A method for promoting combustion of a burner in a kiln device, characterized by promoting mixing of combustion air and fuel particles. 5. A heat transfer between the high temperature exhaust gas and the exhaust heat exchanger is promoted by applying a low frequency sound wave of about 50 Hz or less to the high temperature exhaust gas passing through the exhaust heat exchanger for recovering the heat of the exhaust gas. A method for promoting heat exchange in a heat exchanger in a kiln device. 6. A method for improving thermal efficiency in a kiln device, characterized in that a plurality of arbitrary methods are applied in combination from the low frequency sound wave applying method according to any one of claims (1) to (5). 7. A kiln device comprising a low frequency sound wave generator for generating a low frequency sound wave of about 50 Hz or less near a burner provided on the outlet side of a rotary kiln. 8. A kiln device characterized in that a low-frequency sound wave generator for generating low-frequency sound waves of about 50 Hz or less is provided in a cooling air supply passage of a clinker cooler. 9. A kiln device characterized in that a low-frequency sound wave generator for generating low-frequency sound waves of about 50 Hz or less is provided in a preheater for circulating high-temperature combustion gas provided on the inlet side of a rotary kiln. 10. A low-frequency sound wave generator for providing a low-frequency sound wave of about 50 Hz or less to the combustion air and fuel particles supplied to the burner provided near the exit side of the rotary kiln. Characteristic kiln device. 11. The exhaust heat exchanger through which the high-temperature exhaust gas passes has about 50.
A kiln device provided with a low-frequency sound wave generator for giving low-frequency sound waves below Hz. 12. A kiln device, characterized in that a plurality of arbitrary low frequency sound wave generators according to claim 7 are attached in combination.