JP2010100490A - Method for measuring firing temperature of fired product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correctly measuring the firing temperature of a fired product to be fired in a firing furnace and a method for managing the operating conditions of the firing furnace by using the firing temperature measured by the measuring method. <P>SOLUTION: Cement clinker (the fired product) is withdrawn from the firing furnace to be typified by a rotary kiln for firing the cement clinker and the withdrawn cement clinker is heated to raise the temperature thereof. A temperature at which the void volume being a physical property of the cement clinker starts to be reduced during the time to raise the temperature thereof is obtained and is defined as the firing temperature of the fired product. The firing temperatures of the fired product in the continuous firing furnace are measured successively, thereby the operating conditions, such as the amounts of the raw material and fuel to be charged in the firing furnace, of the firing furnace can be managed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for measuring a firing temperature of a fired product fired in a firing furnace and a method for managing the operating conditions of the firing furnace based on the firing temperature obtained by such a measuring method.

  The properties of cement clinker obtained by firing cement raw material with a rotary kiln, which is a continuous firing furnace, are affected by various factors. For example, the firing temperature in the furnace, the firing time (sintering time in the firing zone), the composition of the raw materials, the particle size, and the like can be mentioned. A cement clinker is obtained as a result of the combination of the various elements.

  Conventionally, as an index for managing the operating conditions in the firing of the rotary kiln, various measured values such as equipment power and gas temperature can be mentioned. In the rotary kiln, the temperature at which the cement clinker is fired is measured. It was extremely difficult to obtain accurate temperature information about the temperature. In other words, a method of measuring the shell temperature from outside the kiln has been proposed, but this method is information on relative temperature level even if the temperature can be measured well, and it cannot detect the internal temperature. There wasn't.

  As another method, a method of measuring the amount of coating on the inside of the rotary kiln has also been proposed, but the amount of coating on the coaching does not accurately indicate relative high and low temperature information. poor.

  Furthermore, it is also considered to measure the temperature inside the rotary kiln from the observation window in front of the kiln with a non-contact type thermometer, but according to this method, the temperature near the kiln at the most, that is, the highest temperature in the rotary kiln. Only the temperature in the cooling region after the temperature region can be measured, and the firing temperature in the rotary kiln, in particular, the maximum firing temperature cannot be measured.

  In the cement industry in recent years, waste is also being used as a fuel for rotary kilns, and the conditions at the time of firing cement clinker are gradually changing, and its management is becoming more important. Under such circumstances, there is a demand for a technique for accurately grasping the firing temperature of the fired product in the rotary kiln, which is useful as data for managing the operating conditions of the rotary kiln.

  Accordingly, an object of the present invention is to provide a measurement method capable of accurately measuring the firing temperature of a fired product in a firing furnace. Another object of the present invention is to provide a method for managing the firing temperature of the firing furnace based on the firing temperature obtained by the measurement method.

As a result of intensive studies to achieve the above object, the present inventors have determined that the firing temperature of the cement clinker, which is a fired product that moves in the rotary kiln, is fixed as a physical property such as the void volume, and the thermal history. I got the knowledge that it will remain as. That is, the amount of voids is minimized at the highest firing temperature that the cement clinker has undergone during firing in the rotary kiln and is taken out from the rotary kiln that is a firing furnace.
As a result of further investigation based on the above knowledge, if the calcined product taken out from the calcining furnace is heated again by reheating and the physical properties such as the void amount of the calcined product at the temperature rising temperature are measured, the calcined product A change in physical properties such as a decrease in porosity occurs when the temperature exceeds the baking temperature of the product, and thereby the baking temperature, which is the temperature at which the fired product is fired in a firing furnace, can be accurately measured. As a result, the present invention has been completed.

  That is, the present invention takes out the fired product from the firing furnace, heats the taken fired product and raises the temperature, and the temperature at which the physical properties of the fired product begins to change at the above temperature rise (hereinafter, the temperature starts to change). This is a method for measuring the firing temperature of a fired product, wherein the temperature is also referred to as the firing temperature of the fired product.

  In addition, the temperature profile in the firing furnace, which is a continuous firing furnace such as the rotary kiln, indicates that the firing temperature in the furnace does not reach the maximum temperature until the cement raw material forms a cement clinker that is a fired product, and the cement clinker It has been confirmed that there is a maximum firing temperature region in the furnace after formation, and the firing temperature of the cement clinker continuously taken out from the firing furnace during operation of the continuous firing furnace is The maximum firing temperature is shown. Therefore, it has been found that the change start temperature of the physical properties of the fired product continuously taken out from the firing furnace is obtained, and the operation condition of the rotary kiln can be managed with the change start temperature as the maximum firing temperature of the fired product.

  That is, according to the present invention, the firing furnace is a continuous firing furnace, and the fired product continuously taken out from the continuous firing furnace is heated to raise the temperature, There is provided a method for operating a continuous firing furnace characterized in that a temperature at which the physical properties of the fired product starts to change is obtained, and the operating conditions of the rotary kiln are managed using the above temperature as the maximum firing temperature of the fired product.

  According to the method of the present invention, it is possible to accurately grasp the firing temperature of the fired product fired in the firing furnace, and the measurement value itself can manage the firing state of the firing furnace. In particular, in a continuous firing furnace, the above measurement is periodically performed on the fired product continuously taken out, and the operating temperature of the rotary kiln is determined by setting the firing temperature obtained by the measurement as the maximum firing temperature in the firing furnace. Can be accurately managed.

  In addition, the method for measuring the temperature to be baked is that the coating that adheres as a by-product to the inner wall of the rotary kiln for producing the cement clinker can also be regarded as a fired product. On the other hand, it is possible to know the distribution of the firing temperature in the rotary kiln by obtaining the change start temperature of the physical properties of the coaching taken out from any plurality of positions, and in examining the operating conditions of the firing furnace It can be used as useful information.

  In the present invention, the firing furnace for firing the fired product to be measured is not particularly limited, and a known firing furnace is used without limitation. A typical kiln is exemplified by a rotary kiln for obtaining a fired product such as cement clinker. In addition, examples of the continuous firing furnace include a tunnel furnace. Moreover, a box furnace etc. are mentioned as a batch-type baking furnace.

  The fired product to be subjected to the measurement method of the present invention is a fired product fired in the firing furnace. Specifically, cement clinker obtained by firing a cement raw material, degreased body obtained by degreasing and firing a green body of ceramic powder such as aluminum nitride powder, and sintered body obtained by sintering and firing the degreased body , Clay mineral sintered bodies, other inorganic sintered bodies, and the like.

  Moreover, when obtaining a fired product such as the cement clinker, a coating that adheres as a by-product in the firing furnace is also included as the fired product targeted by the present invention.

  In the present invention, removal of the fired product from the firing furnace may be performed while the firing furnace is in operation, or may be performed when the operation of the firing furnace is stopped. In general, in a continuous firing furnace, the firing temperature may be measured by using a part of the fired product taken out from a normal takeout part as a sample. In the above continuous firing furnace, when the fired product is taken out from the normal take-out part, which is the front of the kiln in the rotary kiln for producing cement clinker, the firing temperature measured from the fired product is the highest firing temperature in the rotary kiln. It becomes.

  Moreover, when it is difficult to take out the fired product during the operation of the firing furnace, the method of the present invention may be applied by taking it out from a necessary portion when the operation of the firing furnace is stopped. For example, when the firing temperature of the coaching in the rotary kiln is to be measured, the coaching can be taken out from a plurality of arbitrary positions with respect to the longitudinal direction of the kiln when stopped.

  Further, the amount taken out from the firing furnace may be an amount capable of measuring the physical properties in the reheating of the fired product described later. Generally it is 10-500g. In the case of a cement clinker, it is preferable to classify and measure a typical grain system, for example, with an equivalent diameter of 10 to 20 mm, which makes it easy to measure the porosity after firing.

  In the method of the present invention, the calcined product taken out as described above is heated to measure the physical properties of the calcined product at the temperature rising temperature, and the change start temperature of the physical property is obtained as the firing temperature of the calcined product. .

  The physical property of the fired product is a temperature-dependent physical property, and the physical property that changes when the maximum temperature of the thermal history received by the fired product is selected. For example, when the fired product is the cement clinker or the coating, and further, the aluminum nitride degreaser, the physical property is the void amount of the fired product, and the change in the physical property can be confirmed by the decrease in the void amount. It is suitable for accurately measuring the firing temperature.

  For the measurement of the void amount, a known method is employed without any particular limitation. For example, as a method of indirectly measuring the amount of voids, let the liquid be saturated while degassing so that all the voids are filled with liquid, measure the weight in the liquid, and determine the saturated weight and dry weight of the sample. A method of measuring the porosity by a method obtained by measurement (Archimedes method or submerged weighing method), and a direct method include a method of measuring the pore volume per volume with a mercury porosimeter. Further, regarding ceramics such as the aluminum nitride sintered body, the density of the sintered body is given as a physical property to be noted.

  The physical properties may be measured by heating the fired product to raise the temperature, and at any temperature increase temperature. However, if the temperature interval for measuring the physical properties is too large, an accurate change start temperature is confirmed. Can not. Therefore, it is recommended that the interval be 5 to 100 ° C, preferably 10 to 50 ° C.

  As the apparatus used for the heating, a known heating furnace capable of setting the heating temperature is used without particular limitation. For example, an electric furnace is typical. The heating time of the fired product does not need to be excessively long, and is preferably about 15 to 60 minutes, particularly about 20 to 40 minutes. Furthermore, it is desirable that the temperature rise to the heating temperature is as fast as possible, and the most preferable is an aspect in which the temperature is supplied into a heating furnace adjusted to a preset temperature. The atmosphere in the electric furnace is generally sufficient for the atmosphere, but when the target fired product is easily oxidized, it is preferable to heat in a non-oxidizing atmosphere. Incidentally, air is sufficient when the fired product is the cement clinker.

  In the present invention, the method for determining the change start temperature of the physical properties of the fired product is not particularly limited, but a representative method will be described with reference to FIG. FIG. 1 is a plot of the relationship between the heating temperature (horizontal axis) of the cement clinker taken out from the firing furnace and the porosity (vertical axis) at that temperature in the examples. Create a graph showing the relationship between the temperature and the physical property value at that temperature, draw a horizontal line approximated by the measurement point where the porosity is not changed, and a diagonal line approximated by the measurement point where the porosity is changed. Is the firing temperature of the fired product.

  As described above, when the fired product is heated and heated, the porosity, which is the selected physical property, hardly changes until reaching the highest temperature of the thermal history received by the fired product. Decrease as the inflection point when the temperature is exceeded.

  The method for measuring the firing temperature of the fired product of the present invention can manage the firing state of the firing furnace by the measured value itself.

  In particular, the firing furnace is a continuous firing furnace, and for the fired product continuously taken out from the continuous firing furnace, as described in the firing of the cement clinker, the firing temperature of the fired product is set within the firing furnace. It can be regarded as the maximum firing temperature of the fired product at.

  Therefore, it is possible to manage the operating conditions of the rotary kiln by measuring the temperature to be fired by the method of the present invention at any time for the fired product. Specifically, the measured value of the firing temperature is compared with the optimum set value of the maximum firing temperature for the fired product, and the supply amount of fuel, combustion air, and the like supplied for firing is continuously controlled. be able to.

  In addition, the method for measuring the firing temperature of the fired product of the present invention grasps the temperature distribution in the rotary kiln when applied to the coating that adheres as a by-product to the inner wall of the rotary kiln for producing the cement clinker. Is possible. That is, in general, in the firing of the cement clinker, the coating is attached to a region from the point where the clinker which is the fired product starts to be generated and before the kiln from which the fired product is taken out. The physical properties of the coaching are fixed while being fired at the highest firing temperature at the adhesion position. Therefore, the maximum firing temperature at each location in the rotary kiln is estimated by taking out the coaching from an arbitrary plurality of positions with respect to the longitudinal direction of the kiln and obtaining the change start temperature of the physical properties of the coaching taken out at each location. Thus, the temperature distribution in the rotary kiln can be grasped. Such temperature distribution can be used as useful information in examining the operating conditions of the firing furnace.

EXAMPLES Examples will be shown below for specifically explaining the present invention, but the present invention is not limited to these examples.
Example 1
Clinker A is taken out from a great cooler installed in front of a kiln of a rotary kiln for cement clinker (hereinafter also referred to simply as “clinker”), less than 9.5 mm (fine particles), 9.5 mm to 19.5 mm (medium) Grain) and more than 19.5 mm (coarse grains), 50 g of the medium grain portion was separated, and the temperature was changed from 1250 ° C. to 1550 ° C. at intervals of 50 ° C. and heated in an electric furnace. The firing time at this time was 30 minutes at each set temperature.

  The porosity of the fired product obtained at each heating temperature and that not heated was determined by the Archimedes method using an alcohol solvent. The results are shown in Table 1 (FIG. 1).

  From this relationship, it can be seen that the firing temperature of the clinker is about 1400 ° C.

Example 2
About the clinker B extract | collected by the method similar to Example 1 from the rotary kiln from which operating conditions differ from Example 1, it carried out similarly to Example 1, and measured the porosity of the clinker for every heating temperature.

  Table 2 (FIG. 2) shows the relationship between the heating temperature of clinker B and the porosity. From this relationship, it can be seen that the maximum temperature to be fired of this clinker is about 1500 ° C.

  The maximum temperature to be fired was considered to be overfired as the firing temperature of the cement clinker, and the fuel was reduced.

Example 3
In a rotary kiln with different operating conditions from Example 1, two types of clinkers C and D are manufactured by adjusting the amount of fuel used and changing the length of the burner frame for combustion. And collected. Subsequently, the porosity for each heating temperature of each clinker C and D was measured in the same manner as in Example 1.

  Table 3 (FIG. 3) shows the relationship between the clinker C and Table 4 (FIG. 4) shows the relationship between the heating temperature of the clinker D and the porosity. From this relationship, it can be seen that the maximum temperature of the clinker C to be fired is about 1400 ° C., and the maximum temperature of the clinker D to be fired is about 1400 ° C.

  Thus, by monitoring the maximum firing temperature with respect to the length of the burner frame using the method of the present invention, it is possible to adjust the burner frame so as not to reduce the maximum firing temperature.

Example 4
About the clinker E extract | collected from the rotary kiln where the kiln condition is unsatisfactory, it carried out similarly to Example 1, and measured the porosity of the clinker for every heating temperature.

  Table 5 (FIG. 5) shows the relationship between the heating temperature of clinker E and the porosity. From this relationship, it can be seen that the maximum firing temperature of this clinker is about 1350 ° C.

  As a result, it was judged that the decrease in the maximum kiln temperature was the cause, and the operation was carried out to increase the fuel supply amount and restore the kiln condition.

Example 5
Based on the blended cement raw material, raw material pellets were produced in a laboratory, and clinker X was produced by firing at 1450 ° C. for 1 hour in an electric furnace. Using this clinker X as a sample, the porosity of the clinker at each heating temperature was measured in the same manner as in Example 1.

  Table 6 (FIG. 6) shows the relationship between the heating temperature of the clinker X and the porosity. From this relationship, it can be seen that the maximum temperature to be fired of this clinker is about 1450 ° C.

  Thus, it was confirmed that the firing temperature value measured by the measurement method of the present invention was consistent with the (maximum) firing temperature of the clinker in actual firing, and the measurement method of the present invention was accurate. I know that there is.

Example 6
When the kiln was stopped, kiln coaching was sampled every 5 m from the front of the kiln, and coaching with a size of about 9.5 mm to 19.5 mm was collected. For each coaching sampled every 5 m, the maximum firing temperature was determined in the same manner as in Example 1.

  The results are shown in Table 7 and are shown in FIG. 7 as the relationship between the distance from the front of the kiln and the maximum firing temperature.

The temperature distribution in the rotary kiln (the highest temperature reached at each location) becomes clear from the results obtained in this way. Such data is useful information in examining the operating conditions of the rotary kiln, and the best kiln condition can be adjusted.

In Example 1, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 2, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 3, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 3, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 4, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 5, the graph which shows the relationship between the heating temperature (horizontal axis) of the taken-out cement clinker, and the porosity (vertical axis) in the temperature In Example 6, the graph which shows the relationship between the to-be-fired temperature (vertical axis) of the taken-out coaching, and a taking-out location (horizontal axis)

Claims (4)

Taking out the fired product from the firing furnace, heating the taken-out fired product to raise the temperature, obtaining a temperature at which the physical properties of the fired product begin to change at the above temperature rise, and determining the temperature as the firing temperature of the fired product A method for measuring a firing temperature of a fired product. The method according to claim 1, wherein the physical property is a void amount of the fired product, and the change in the physical property is a decrease in the void amount. The method according to claim 1 or 2, wherein the firing furnace is a rotary kiln for cement raw material firing, and the fired product is a cement clinker. The firing furnace is a continuous firing furnace, and the fired product continuously taken out from the continuous firing furnace is heated to raise the temperature of the fired product, and the physical properties of the fired product begin to change at the above temperature rise. A method for operating a continuous firing furnace, characterized in that a temperature is obtained, and the operation condition of the rotary kiln is managed using the above temperature as the maximum firing temperature of the fired product.

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