Evaluation method for exhaust gas odor, method for use of cement raw material

Abstract

To provide a method enabling odor of exhaust gas occurring when cement raw material is heated, to be estimated as a value similar to a value in an actual condition.SOLUTION: An odor evaluation method comprises: a step (a) in which information related to a first odor index which is an odor index of an exhaust gas occurring when first cement raw material is heated, and information related to a second odor index which is an odor index of the exhaust gas when a second cement raw material being produced from a material different from that of the first cement raw material is heated; a step (b) in which a third odor index which is an odor index of the exhaust gas occurring when a third cement raw material being produced by mixing the first cement raw material and the second cement raw material is heated, by calculation based on a mixing ratio of the first cement raw material and the second cement raw material, the first odor index and the second odor index.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating the odor of exhaust gas, and more particularly to a method for evaluating the odor of exhaust gas generated when a cement raw material is heated. The present invention also relates to a method for using the cement raw material using the evaluation method. [Background technology]

[0002] Currently, efforts are being made to use waste materials as part of the raw materials for cement in order to realize a sustainable society. A specific example is a method in which raw materials containing limestone and clay, which are obtained by crushing in a raw material mill at a cement factory (hereinafter referred to as "main cement raw materials"), are mixed with raw materials made from waste materials (hereinafter referred to as "recycled raw materials"), and then the mixture is put into a cement kiln and fired.

[0003] However, there is concern that the odors contained in cement kiln exhaust gases will increase due to the diversification of waste materials and the associated diversification of by-products produced by burning waste materials. The substances that cause odors in exhaust gases are the carbon and organic matter contained in some of the recycled materials that volatilize or are burned. Therefore, from the perspective of managing and monitoring the odors in exhaust gases, it is important to evaluate the degree to which the carbon and organic matter contained in recycled materials affect the odors.

[0004] The following Patent Document 1 discloses a technology for quantifying specific odorous substances (22 substances) generated by heating cement raw materials to obtain odor data, and then estimating the impact of the specific odorous substances on exhaust gas odors from their odor index equivalent values ​​and unit consumption values. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6135371 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the recent diversification of recycled materials, it is assumed that the odor of cement kiln exhaust gas is caused by substances other than the above 22 types of specific odorous substances. In other words, the odor of exhaust gas exists as a "complex odor" that is a mixture of a wide variety of substances that have an odor, or in other words, have an odor that exceeds the olfactory threshold. Therefore, it is considered that the value evaluated by the technology of Patent Document 1 does not match the actual odor intensity.

[0007] In view of the above circumstances, an object of the present invention is to provide a method that makes it possible to evaluate the odor of exhaust gas generated when cement raw materials are heated as a value closer to the actual situation than has been conventionally achieved.

[0008] Another object of the present invention is to provide a method for using cement raw materials, which makes it possible to suppress the odor of exhaust gas generated when the cement raw materials are heated to a threshold value or less, based on the evaluation results of the odor of the exhaust gas obtained using the above-mentioned method. [Means for solving the problem]

[0009] The odor evaluation method for exhaust gas according to the present invention includes the steps of: A step (a) of preparing information on a first odor index, which is an odor index of an exhaust gas generated when a first cement raw material is heated, and information on a second odor index, which is an odor index of an exhaust gas generated when a second cement raw material made of a material different from the first cement raw material is heated; and (b) estimating a third odor index, which is an odor index of exhaust gas generated when a third cement raw material obtained by mixing the first cement raw material and the second cement raw material is heated, by calculation based on the mixing ratio of the first cement raw material and the second cement raw material, the first odor index, and the second odor index.

[0010] The "Odor Index" is a numerical value that represents the strength of an odor based on the human sense of smell. An example of a method for measuring the odor index is provided in the Environment Agency Notification No. 63 of 1995 as the "Method of Calculating the Odor Index." For a more detailed example, the "Triple Comparison Odor Bag Method" described in the appendix to the notification can be used.

[0011] However, in this specification, the term "odor index" is used to mean a numerical value that quantifies the intensity of an odor based on human olfaction, and is not limited to the value measured using the method specified in the above notification.

[0012] One known method for easily measuring odors in gas is to use an "odor sensor" including a semiconductor sensor. An odor sensor is a technology that measures odors by utilizing the change in resistance of a semiconductor due to the adsorption of odor molecules on the semiconductor surface.

[0013] As described later in the section "Mode for Carrying Out the Invention," there is a high correlation between the odor measured using an odor sensor to measure the odor in the exhaust gas generated when cement raw materials are heated, and the odor index measured using a triangle odor bag method for the exhaust gas. Therefore, based on the correlation between the odor sensor measurement value and the odor index, an odor index corresponding to the measurement value (actual measurement value) when the odor in the exhaust gas is actually measured using an odor sensor can be derived, and the derived odor index can be recognized as the odor index of the exhaust gas.

[0014] More specifically, the step (a) comprises: A step (a1) of measuring an odor of exhaust gas generated when the first cement raw material is heated using an odor sensor to obtain a first measurement value; (a2) measuring an odor of exhaust gas generated when the second cement raw material is heated using an odor sensor to obtain a second measurement value; The method may include a step (a3) ​​of deriving the first odor index, which is an odor index value corresponding to the first measurement value, and the second odor index, which is an odor index value corresponding to the second measurement value, based on a relative relationship between the measurement value by the odor sensor and the odor index that has been registered in advance.

[0015] The first odor index is a value based on human olfaction in accordance with the odor intensity of the exhaust gas (hereinafter simply referred to as the "first exhaust gas") generated when the first cement raw material is heated, and is not a value calculated by performing an operation on the odor intensity derived from each component based on the component ratio of the first exhaust gas. The same is true for the second odor index, which is a value based on human olfaction in accordance with the odor intensity of the exhaust gas (hereinafter simply referred to as the "second exhaust gas") generated when the second cement raw material is heated, and is not a value calculated by performing an operation on the odor intensity derived from each component based on the component ratio of the second exhaust gas.

[0016] For example, when the second cement raw material is waste α, the odor index of the exhaust gas generated when the waste α is heated can be derived in advance, and this odor index can be used as the second odor index. Also, when the second cement raw material is waste β different from the waste α, the odor index of the exhaust gas generated when the waste β is heated can be derived in advance, and this odor index can be used as the second odor index. In other words, even when a wide variety of recycled raw materials are used as the second cement raw material, the odor index of the exhaust gas generated when the recycled raw materials used are heated can be derived in advance, and the second odor index can be based on the result, so that the odor intensity of the exhaust gas corresponding to the recycled raw materials used can be predicted.

[0017] In addition, when the first cement raw material and the second cement raw material, which have different odor indices, are mixed to contribute to cement production, it becomes possible to estimate the odor of the exhaust gas generated when the mixed cement raw material (third cement raw material) is heated based on the odor index and the mixing ratio of each. That is, as in the above step (b), it becomes possible to estimate the third odor index, which is the odor index of the exhaust gas (hereinafter referred to as the "third exhaust gas") generated when the third cement raw material is heated, by a calculation including the mixing ratio of the first cement raw material and the second cement raw material, the first odor index, and the second odor index.

[0018] This makes it possible to evaluate the odor intensity of the exhaust gas generated when the first cement raw material and the second cement raw material are mixed and used in cement production, based on the third odor index derived in the step (b).

[0019] In the step (a), it is not necessary to adopt an odor index obtained based on exhaust gas generated when the cement raw materials are heated using a cement kiln into which the cement raw materials are actually charged, but an odor index obtained based on exhaust gas generated when the cement raw materials are heated in a simulated environment of a cement kiln and a preheater attached thereto can be adopted. Information related to the obtained odor indexes (first odor index, second odor index) may be recorded in a storage medium (flash memory, cloud server, etc.).

[0020] The above-mentioned "first cement raw material" is not limited to a raw material made of a single material, and may be a raw material made of a mixture of multiple materials. Similarly, the "second cement raw material" is not limited to a raw material made of a single material, and may be a raw material made of a mixture of multiple materials.

[0021] The first odor index is an odor index of exhaust gas generated when the first cement raw material is heated in a heating environment in a preheater attached to a cement kiln, The second odor index may be an odor index of exhaust gas generated when the second cement raw material is heated in a heating environment in the preheater.

[0022] When burning cement raw materials, they are generally charged from the top of the preheater. As they pass through the preheater, the temperature of the cement raw materials gradually increases while exchanging heat with the combustion exhaust gas from the cement kiln, and they are eventually charged into the cement kiln. Typically, the cement raw materials are in a temperature environment of 500°C to 600°C when they pass through the top of the preheater, and in a temperature environment of 800°C to 1,000°C when they reach the bottom of the preheater. When they are charged into the cement kiln, they are in a temperature environment of 1,000°C or more, more typically about 1,300°C to 1,500°C.

[0023] The odor of exhaust gas (kiln exhaust gas) generated when cement raw materials are heated is caused by hydrocarbon compounds (organic components) such as acetaldehyde. It is believed that the substances that cause this odor are generated when organic matter contained in the cement raw materials is incompletely combusted inside the preheater, more specifically, on the upper side of the preheater. Meanwhile, near the preheater inlet, the temperature of the exhaust gas is high, and the time required for the exhaust gas to pass through the preheater before reaching the preheater outlet is also long, so that much of the organic matter contained in the cement raw materials is oxidized and decomposed, releasing CO 2 In other words, it is considered that the amount of odor-causing substances produced near the exhaust gas preheater inlet is low or almost non-existent.

[0024] The first odor index is preferably the odor index of exhaust gas generated when the first cement raw material is heated in a preheater, more specifically, in a heating environment in the upper part of the preheater. The same applies to the second odor index. More specifically, the heating environment can be an environment in which the first cement raw material is heated at a heating temperature of 400°C to 600°C, with an atmospheric oxygen concentration of 1% to 8%, for a heating time of 10 minutes to 20 minutes. This numerical range corresponds to the temperature environment when the cement raw material passes through a preheater when it is charged from the upper side of the preheater attached to a typical cement kiln.

[0025] The method for using the cement raw material according to the present invention includes the steps of: A step (a) of preparing information on a first odor index, which is an odor index of an exhaust gas generated when a first cement raw material is heated, and information on a second odor index, which is an odor index of an exhaust gas generated when a second cement raw material made of a material different from the first cement raw material is heated; a step (b) of estimating a third odor index, which is an odor index of exhaust gas generated when a third cement raw material obtained by mixing the first cement raw material and the second cement raw material is heated, by calculation based on a mixing ratio of the first cement raw material and the second cement raw material, the first odor index, and the second odor index; and (c) comparing an evaluation value based on the third odor index with a predetermined threshold value, and if the evaluation value is equal to or less than the predetermined threshold value, feeding the third cement raw material from above a preheater attached to a cement kiln.

[0026] According to the above method, before the third cement raw material is actually charged into the cement kiln from above the preheater, the odor of the exhaust gas (third exhaust gas) generated by heating the third cement raw material in step (b) can be estimated by the odor index, which is a value based on the human sense of smell.

[0027] Here, the "evaluation value" may be the value of the third odor index itself, or may be a value resulting from a calculation using the value of the third odor index. As an example of the latter, the ratio of the third odor index to the smaller of the first odor index and the second odor index (here, the first odor index) may be used. As another example, the difference between the third odor index and the first odor index may be used. The "evaluation value" used here is a value that shows a positive correlation with the third odor index.

[0028] If it is confirmed that the evaluation value is equal to or less than the predetermined threshold value that is the standard for the occurrence of offensive odors, it is expected that the odor of the exhaust gas can be suppressed to or less than the standard value even if the third cement raw material is actually charged from the top of the preheater toward the cement kiln. Therefore, according to the above method, it is possible to charge a cement raw material (third cement raw material) made of a mixture of multiple cement raw materials from the top of the preheater in the same way as a normal cement raw material (main cement raw material), while suppressing the occurrence of offensive odors.

[0029] In the step (c), if the evaluation value exceeds the predetermined threshold, the mixing ratio may be changed so that the evaluation value becomes equal to or less than the predetermined threshold, and the third cement raw material may be charged from an upper portion of the preheater.

[0030] According to the above method, even if the third cement raw material after the mixing ratio has been changed is actually charged from above the preheater toward the cement kiln, the odor of the exhaust gas can be suppressed to below the standard value.

[0031] The second odor index is higher than the first odor index, In the step (c), when the evaluation value exceeds the predetermined threshold, the mixing ratio is changed by decreasing a relative ratio of the second cement raw material to the first cement raw material so that the evaluation value is equal to or less than the predetermined threshold, and then the third cement raw material is charged from an upper portion of the preheater; The method may further include a step (d) of feeding the second cement raw material from a lower portion of the preheater.

[0032] When the second odor index is higher than the first odor index, it is expected that the odor of the exhaust gas generated when the third cement raw material is heated increases as the ratio (mixing ratio) of the second cement raw material contained in the mixed cement raw material (third cement raw material) increases. Here, in the step (c), when the evaluation value exceeds a predetermined threshold value that is a criterion for the occurrence of a bad odor, it is preferable to reduce the ratio of the second cement raw material contained in the third cement raw material to reduce the third odor index and make the evaluation value equal to or lower than the predetermined threshold value, from the viewpoint of suppressing the occurrence of a bad odor. However, in this case, it is expected that the consumption rate of the second cement raw material received at the cement plant will be slowed down.

[0033] As mentioned above, the lower part of the preheater is in a higher temperature environment than the upper part of the preheater. Therefore, when the second cement raw material is added from this point, most of the organic matter contained in the second cement raw material is completely oxidized and CO 2 It is expected that the amount of odor-causing substances produced will be low or almost nonexistent.

[0034] Therefore, by reducing the ratio of the second cement raw material to make the evaluation value equal to or less than a predetermined threshold value, and further adding the second cement raw material from the bottom of the preheater as in process (d), it is possible to suppress the generation of bad odors while increasing the consumption of the second cement raw material which has a high odor index.

[0035] Here, "adding from the bottom of the preheater" refers to the preheater inlet for exhaust gas, which includes the case of adding from the bottom of the cement kiln, as well as the case of adding from the cyclone closest to the cement kiln (hereinafter referred to as the "lowest cyclone") when the preheater is composed of multiple stages of cyclones, the case of adding from the cyclone located just before the lowest cyclone, and the case of adding from piping connecting these cyclones.

[0036] The first cement raw material is a blended raw material blended in a raw material step, The second cement raw material may be a waste material.

[0037] The "mixed raw materials prepared in the raw material process" corresponds to the main cement raw materials mentioned above. The waste materials that can be used include general waste and industrial waste that are mainly organic and combustible, such as waste plastics, wood chips, sludge, construction soil, ASR, waste tires, carbon fiber, carbon fiber reinforced plastics (CFRP), meat and bone meal, and biomass. Effect of the Invention

[0038] According to the present invention, it is possible to evaluate the odor of exhaust gas generated when cement raw materials are heated as a value close to the actual situation. [Brief description of the drawings]

[0039] [Figure 1] 1 is a flowchart showing an example of a procedure for carrying out a method for using a cement raw material according to the present invention. [Diagram 2] 2 is a flowchart showing an example of a detailed procedure of step #1 in FIG. 1. [Diagram 3] FIG. 1 is a block diagram showing a schematic example of a method for conducting an odor evaluation test. [Figure 4] 1 is a schematic diagram of a cement manufacturing apparatus including a cement kiln and a preheater attached to the cement kiln. [Diagram 5] FIG. 1 is a block diagram showing a schematic configuration of an evaluation combustion system including a test kiln. [Figure 6] This is a graph plotting the correspondence between the actual odor index values ​​(relative values) measured by a method based on the triangle comparison odor bag method and the estimated odor index values ​​(relative values) obtained by calculation. [Figure 7] 1 is a graph plotting the correspondence between the actual odor index values ​​(relative values) measured according to a method based on the triangle comparison odor bag method and the measured values ​​(relative values) measured using an odor sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The embodiment of the method for evaluating odor of exhaust gas and the method for using cement raw materials according to the present invention will be described with reference to the drawings as appropriate. Note that the drawings are schematic, and the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0041] The odor evaluation method for exhaust gas according to the present invention is a method for evaluating odors generated when a cement raw material made of a mixture of cement raw materials made of different materials is heated. Hereinafter, the cement raw materials made of different materials are referred to as a "first cement raw material C1" and a "second cement raw material C2", respectively. Also, the cement raw material made by mixing the first cement raw material C1 and the second cement raw material C2 is referred to as a "third cement raw material C0".

[0042] In the following, a case where the third cement raw material C0 is obtained by mixing two types of cement raw materials (C1, C2) will be described. However, a similar explanation can be applied to a case where the third cement raw material C0 is obtained by mixing three or more types of cement raw materials (C1, C2, C3, ...).

[0043] Figures 1 and 2 are flow charts showing an example of a procedure for carrying out a method for using cement raw materials according to the present invention. The procedure for carrying out a method for evaluating odor of exhaust gas according to the present invention is included as part of the procedure of the method for using cement raw materials shown in Figures 1 and 2. In the following description, the step numbers shown in Figures 1 and 2 will be referred to as appropriate.

[0044] (Preparation of information on odor index) First, a preparation step is performed (Step #1). Fig. 2 is a flow chart showing an example of a detailed procedure of Step #1. As shown in Fig. 2, by performing Step #1, odor indices corresponding to the first cement raw material C1 and the second cement raw material C2 are recorded.

[0045] Specifically, odor evaluation tests are conducted on the first cement raw material C1 and the second cement raw material C2, respectively (steps #11 and #21). In the following, the odor evaluation test on the first cement raw material C1 will be described as an example.

[0046] Specifically, the first cement raw material C1 is heated under a prescribed heating environment, the resulting gas (exhaust gas) is extracted, and the odor is evaluated by a prescribed method. Here, the prescribed heating environment is the heating environment in a preheater attached to a cement kiln, more specifically, an environment simulating the upper side of the preheater. Typically, the first cement raw material C1 is heated at a heating temperature of 400°C to 600°C, with an atmospheric oxygen concentration of 1% to 8%, for a heating time of 10 to 20 minutes, and the resulting exhaust gas is extracted.

[0047] 3 is a block diagram showing a schematic example of a method for performing an odor evaluation test. The odor evaluation device 10 includes an air pump 11 for supplying air A1, a nitrogen gas source 12 for supplying nitrogen gas A2, a heating chamber 13 into which a mixed gas A3 of air A1 and nitrogen gas A2 is introduced, and a heating mechanism 14 for heating the heating chamber 13. The oxygen concentration of the mixed gas A3 can be adjusted by controlling a valve 17 while detecting the flow rates of the air A1 and the nitrogen gas A2 with flow meters (11a, 12a), respectively. Note that instead of controlling the valve 17, the oxygen concentration of the mixed gas A3 may be adjusted by controlling the opening of a valve connected to the nitrogen gas source 12 or a valve connected to the air pump 11.

[0048] The heating chamber 13 is, for example, a tube made of a material exhibiting high heat resistance, and is formed of ceramic such as alumina as an example. The heating mechanism 14 is an annular furnace that covers the outer periphery of the heating chamber 13, and is, for example, an electric furnace. The first cement raw material C1 to be heated is placed in the heating chamber 13. As a more detailed example, for example, a highly heat-resistant container 18 is placed in the heating chamber 13 with the first cement raw material C1 contained in the container 18.

[0049] Mixed gas A3 with an oxygen concentration set to 1% to 8% is introduced into heating chamber 13. In an atmosphere of this mixed gas A3, thermal energy is supplied from heating mechanism 14, thereby creating a heated environment space 13A exhibiting a temperature of 400°C to 600°C in heating chamber 13. By placing cement raw material C1 in this heated environment space 13A for 10 to 20 minutes, a heating environment equivalent to that when first cement raw material C1 passes through a preheater is simulated.

[0050] The exhaust gas A5 obtained by heating the first cement raw material C1 is sent to the gas bag 16 and collected.

[0051] However, the method of performing the odor evaluation test shown in Fig. 3 is merely one example. Step #11 may be performed in a different manner as long as the exhaust gas A5 obtained by heating the first cement raw material C1 in a heating environment equivalent to that during passage through the preheater can be collected.

[0052] Next, the odor index I of the exhaust gas A5 obtained by heating the first cement raw material C1 2 is derived (step #12).

[0053] As a method for deriving the odor index of exhaust gas A5, for example, the "three-point comparison odor bag method" described in the appendix of the Environment Agency Notification No. 63 of 1995 can be used. Another method is to supply exhaust gas A5 to an odor sensor including a semiconductor sensor, obtain the measurement value of the odor sensor, and derive the odor index from the measurement value based on the correlation between the odor sensor and the odor index. The obtained odor index I 1 The information is recorded in the storage medium (step #13). 1 corresponds to the "first odor index."

[0054] The odor index I is a value calculated by I=10×Log N where N is the odor concentration. The odor concentration N corresponds to the dilution factor at which the target gas is diluted with odorless air and begins to become undetectable to the human sense of smell. For example, if the target gas is diluted 100 times and the odor becomes undetectable for the first time, then the odor concentration N=100 and the odor index I=20.

[0055] The second cement raw material C2 was also heated in the same heating environment as when it passed through the preheater, just like the first cement raw material C1, and the exhaust gas A5 was sampled and measured for odor index I. 2 The odor index I corresponding to the second cement raw material C2 is calculated and recorded (steps #21 to #23). 2 corresponds to the "second odor index."

[0056] The preparation step #1 is carried out by the above steps #11 to #13 and #21 to #23.

[0057] Next, the mixing ratio of the first cement raw material C1 and the second cement raw material C2 to realize the third cement raw material C0 is set (step #2). For example, if 60% of the third cement raw material C0 is composed of the first cement raw material C1 and 40% of the second cement raw material C2, the mixing ratio U of the first cement raw material C1 is set to 100%. 1 = 0.6, the mixture ratio U of the second cement raw material C2 2 = 0.4, and the mixture ratio of the two is 3:2. 1 ,U 2 is expressed as an internal division.

[0058] Next, the odor index (third odor index I) of the exhaust gas generated when the third cement raw material C0, which is obtained by mixing the first cement raw material C1 and the second cement raw material C2 under the mixing ratio set in step #2, is heated is calculated. 3 ) is derived by calculation based on the result obtained in step #1 (step #3).

[0059] It is expected that the more raw materials that produce exhaust gas with a strong odor when heated, the stronger the odor of the exhaust gas produced when the third cement raw material C0 is heated. In other words, the odor concentration of the exhaust gas produced when the first cement raw material C1 is heated (hereinafter referred to as the "first exhaust gas") is N 1 The odor concentration of the exhaust gas generated when the second cement raw material C2 is heated (hereinafter referred to as the "second exhaust gas") is N 2 The odor concentration of the exhaust gas (hereinafter referred to as "third exhaust gas") generated when the third cement raw material C0 is heated is N 0 Then, the odor concentration of the third exhaust gas is N 0 is the mixture ratio U 1 , U 2 Using this, it can be estimated using the following equation (1).

[0060]

number

[0061] According to the definition of odor concentration, the odor concentration of the first exhaust gas is N 1 , and the odor concentration N2 of the second exhaust gas are the first odor index I 1 , and the second odor index I 2 Using these, it is expressed by the following equations (2a) and (2b).

[0062]

number

[0063] Based on the formulas (1), (2a), and (2b), the third odor index of exhaust gas (third odor index I 0 ) can be estimated using the following equation (3):

[0064]

number

[0065] According to the above formula (3), the first odor index I derived in step #1 1and the second odor index I 2 The information on the mixture ratio U of the first cement raw material C1 mixed to obtain the third cement raw material C0 1 and the blending ratio U of the second cement raw material C2 1 Based on this, the odor index of the third exhaust gas generated when the third cement raw material C0 is heated (third odor index I 0 ) can be estimated by calculation.

[0066] Next, the third odor index I derived in step #3 0 Based on this, an evaluation value Y for evaluating the odor of the third exhaust gas generated when the third cement raw material C0 is heated is calculated (step #4). As the evaluation value Y, the third odor index I 0 The value itself can be adopted, or the third odor index I 3 For the sake of simplicity, it is assumed here that the evaluation value Y is the third odor index I 0 The explanation will be continued by taking the case where the value is the actual value as an example.

[0067] Next, the evaluation value Y derived in step #4 and a preset reference threshold Y r (Step #5) Compare with the reference threshold Y r is preferably set to a value that is a standard for determining whether the odor of the exhaust gas is an unpleasant odor. r If the evaluation value Y exceeds the standard threshold Y, the odor problem will become apparent from the third exhaust gas generated when the third cement raw material C0 is heated. r If this is the case, it can be determined that the problem of unpleasant odors will not become apparent from the third exhaust gas generated when the third cement raw material C0 is heated.

[0068] The evaluation value Y is the third odor index I 0 In this case, the standard threshold Y r For example, a standard threshold Y r can be set.

[0069] Evaluation value Y is the standard threshold Y r If it is equal to or lower (Yes in step #5), the third cement raw material C0 is fed from the top of the preheater toward the cement kiln and used in cement production (step #6).

[0070] FIG. 4 is a schematic diagram of a cement manufacturing apparatus including a cement kiln and a preheater attached to the cement kiln. The cement manufacturing apparatus 1 shown in FIG. 4 includes a cement kiln 6 provided with a burner 7 and a preheater 5 connected above the cement kiln 6. In the example of FIG. 4, the preheater 5 includes five stages of cyclones, and the raw materials fed from the raw material feed port 21 are preheated by passing through the cyclones 5a, 5b, 5c, 5d, and 5e in this order and then fed into the cement kiln 6. In each cyclone (5a, 5b, 5c, 5d, 5e), the high-temperature gas discharged from the cement kiln 6 flows in, and heat exchange is performed between the raw materials. In other words, the gas discharged from the cement kiln 6 flows in the opposite direction to the flow of the raw materials, so that the environmental temperature becomes lower the further above the preheater 5 it is. In other words, cyclone 5a has the lowest temperature, and the environmental temperature becomes higher in the order of cyclone 5b, cyclone 5c, cyclone 5d, and cyclone 5e.

[0071] As described above, the first odor index I set in step #1 1 and the second odor index I 2 Both of these correspond to the odor index of exhaust gas generated when cement raw materials (C1, C2) are heated under the same heating environment as when passing through a preheater. Therefore, this first odor index I 1 and the second odor index I 2 The third odor index I calculated based on 0 , and the evaluation value Y based thereon are based on the odor index of the exhaust gas generated when the third cement raw material C0 is heated under the same heating environment as when it passes through a preheater.

[0072] Therefore, in step #5, the evaluation value Y is equal to the reference threshold Y r The case where the evaluation value Y is equal to or less than the reference threshold value Y corresponds to the case where the exhaust gas generated when the third cement raw material C0 obtained by mixing the first cement raw material C1 and the second cement raw material C2 at the mixing ratio set in step #2 is charged from above the preheater 5 through the raw material charging port 21 shown in FIG. 4 is at a level where odor problems are not evident. r If it is equal to or less than this (Yes in step #5), even if the third cement raw material C0 is charged from above the preheater 5 toward the cement kiln 6 (step #6), the generation of unpleasant odors in the exhaust gas can be suppressed.

[0073] On the other hand, the evaluation value Y is the standard threshold Y r If it exceeds this limit (No in step #5), then when the third cement raw material C0 is fed from the top of the preheater toward the cement kiln, there is a concern that the odor problem of the exhaust gas will become apparent.

[0074] In this case, the mixing ratio of the first cement raw material C1 and the second cement raw material C2 is changed (step #7), and the third odor index I is calculated again. 0 and the evaluation value Y are calculated (steps #3 and #4). Note that, in the case where the first cement raw material C1 is a blended raw material (main cement raw material) containing clay and the like and blended in the raw material process, and the second cement raw material C2 is a waste, step #7 is actually performed by calculating the mixing ratio of the second cement raw material C2 in the third cement raw material C0, that is, the blending ratio U 2 This is a process that reduces the value of

[0075] For the third cement raw material C0 adjusted by changing the mixing ratio of the first cement raw material C1 and the second cement raw material C2, the evaluation value Y is r If it is equal to or less than the standard threshold value Y, the third cement raw material C0 obtained under the adjusted mixing ratio is fed from the top of the preheater 5 to the cement kiln 6 (step #6). In this case, the generation of unpleasant odors in the exhaust gas can be suppressed. Even after the mixing ratio is adjusted, the evaluation value Y continues to be equal to or less than the standard threshold value Yr If it exceeds this value (No in step #5), the mixing ratio is adjusted again, and steps #3 to #5 are then repeated.

[0076] According to the above method, the evaluation value Y is set to a reference threshold Y r In step #7, the proportion of the second cement raw material C2 is reduced, which means that the consumption rate of the second cement raw material C2 is reduced, in order to: If the second cement raw material C2 is a waste product, there may be limitations on the amount of waste that can be accepted at the cement plant.

[0077] Therefore, when it is necessary to ensure a certain degree of consumption rate of the second cement raw material C2 (Yes in step #8), at least a part of the remaining second cement raw material C2 not used in producing the third cement raw material C0 may be fed from the bottom of the preheater 5 toward the cement kiln 6 (step #9). In the cement manufacturing apparatus shown in Fig. 4 as an example, the second cement raw material C2 may be fed toward the cement kiln 6 from the raw material feeding port 22.

[0078] Unlike the upper part of the preheater 5, the bottom of the cement kiln 6 is subjected to an extremely high temperature environment. Therefore, even if the second cement raw material C2 is made of a material with a relatively high odor index, such as waste, when it is heated in such a high-temperature environment, most of the organic matter contained in the second cement raw material C2 is oxidized and decomposed, emitting CO 2 Therefore, by feeding a portion of the second cement raw material C2 from the lower part of the preheater 5 toward the cement kiln 6, it is possible to increase the consumption rate of the second cement raw material C2 while suppressing the problem of unpleasant odors originating from the second cement raw material C2.

[0079] From the viewpoint of thermal efficiency, it is not preferable to charge all of the raw materials from the lower part of the preheater 5. According to the above method, the cement raw material (third cement raw material C0) is charged from the upper part of the preheater 5 within a range in which the problem of nasty odors does not become apparent, so that cement clinker can be produced without a significant decrease in thermal efficiency. Furthermore, when there is a need to increase the consumption rate of the second cement raw material C2, at least a portion of the remaining second cement raw material C2 that was not used in producing the third cement raw material C0 can be charged from the lower part of the preheater 5, thereby increasing the consumption rate of the second cement raw material C2 while suppressing the generation of nasty odors.

[0080] As the odor evaluation method for exhaust gas, steps #1 to #3 or steps #1 to #4 are performed. As the usage method for cement raw materials, steps #1 to #9 are performed. However, as the usage method for cement raw materials, it is optional whether or not to perform steps #8 to #9. EXAMPLES

[0081] The method according to the present invention will be described in detail below with reference to examples. However, the following examples are merely illustrative and the present invention is not limited to the following examples.

[0082] (Verification 1: Odor index measurement) Six different kinds of raw materials (hereinafter referred to as "raw material R1" to "raw material R6") were heated using the odor evaluation device 10 shown in Fig. 3, and the generated exhaust gas was measured to obtain an odor index. The details of the odor evaluation device 10 are as follows.

[0083] Heating chamber 13: Alumina tube (furnace tube) with an inner diameter of 70 mm, an outer diameter of 80 mm, and a length of 1,000 mm Heating mechanism 14: KOYO THERMO CO., LTD., circular electric furnace KTF434N Air pump 11: Fuji Clean Kogyo Co., Ltd., diaphragm blower for septic tanks EcoMac30 Nitrogen gas source 12: Nitrogen gas with a purity of 99.9995 vol% or higher, manufactured by Taiyo Nippon Sanso Corporation Container 18: Made of alumina, dimensions of containment area: 30mm x 15mm x 150mm Gas bag 16: Freck sampler with a volume of 10 L Flowmeter 11a, 11b: KOFLOC Mass Flow Controller 8500MC

[0084] The heating conditions were set as shown in Table 1 below.

[0085] [Table 1]

[0086] A heating test was carried out for each of the raw materials R1 to R6 in the following manner, and the exhaust gas A5 was stored in the gas bag 16.

[0087] The power of the tubular electric furnace serving as the heating mechanism 14 was turned on, and the temperature was raised to 600° C. Next, the flow rates of the air A1 and the nitrogen gas A2 were adjusted to 170 mL / min and 530 mL / min, respectively, and a mixed gas A3 of the two was introduced into the furnace tube serving as the heating chamber 13.

[0088] After confirming with a gas analyzer that the oxygen concentration of the gas exhausted from the outlet of the heating chamber 13 was 5%, the container 18 containing 10 g of the raw material R1 was placed near the center inside the furnace tube (inside the heating environment space 13A), whereby heating of the raw material R1 was started.

[0089] After exhausting gas from the outlet of the heating chamber 13 for 1 minute from the start of heating, the exhausted gas (exhaust gas A5) was collected in the gas bag 16 for 14 minutes. After the collection was completed, the container 18 containing the raw material R1 was removed to the outside of the heating chamber 13, and the gas inside the heating chamber 13 was replaced by ventilating it for 10 minutes.

[0090] Next, a container 18 containing raw material R2 instead of raw material R1 was placed near the center inside the furnace tube. Similar treatments were then carried out for each of raw materials R3 to R6.

[0091] In this way, each of the raw materials R1 to R6 was heated and the odor index of each of the exhaust gases A5 collected in the gas bag 16 was measured using a method that conforms to the triple comparison odor bag method described in the appendix to the Environment Agency Notification No. 63 of 1995. The measurement results are shown in Table 2. However, in Table 2, the odor index of each raw material is listed as a relative value to the odor index of raw material R1.

[0092] [Table 2]

[0093] (Verification 2: Odor index estimation) Next, the odor index of each of the raw materials S1 to S16 obtained by mixing the other raw materials (raw materials R2 to R6) with the raw material R1 in a specified ratio was estimated based on the calculation of the above formula (3). The mixing conditions and the estimation results are shown in Table 3. However, since raw material S1 is a raw material in which no other raw materials are mixed with raw material R1, it is substantially the same as raw material R1.

[0094] In Table 3, the "mixing ratio" is a value expressed as a percentage. The estimated odor index values ​​of raw materials S1 to S16 are expressed as relative values ​​based on the odor index of raw material R1 (estimated odor index value of raw material S1). The numerical values ​​in parentheses next to each of raw materials R1 to R6 are the odor index values ​​shown in Table 2.

[0095] [Table 3]

[0096] (Verification 3: Odor evaluation of mixed raw materials) Next, the raw materials S1 to S16 shown in Table 3 were heated in a test kiln simulating an actual cement kiln, and the resulting exhaust gas was collected and its odor was measured using a method based on the triple-comparison odor bag method.

[0097] Fig. 5 is a block diagram showing a schematic configuration of an evaluation combustion system including a test kiln. In Fig. 5, the flow of solids such as raw materials is shown by a dashed line, and the flow of gases such as exhaust gas is shown by a dashed line.

[0098] The evaluation combustion system 30 includes a test kiln 31, an exhaust duct 32, and a cyclone 36. The internal space of the test kiln 31 is heated by a burner 33. A cyclone 36 simulating a preheater and an exhaust duct 32 are attached to the upstream side (bottom side) of the test kiln 31. A conveyor 34 is installed above the exhaust duct 32, and raw materials supplied from a raw material storage section 35 can be fed from the top of the preheater through the conveyor 34 toward the test kiln 31. A conveyor 47 is installed on the bottom side of the test kiln 31, and raw materials supplied from a raw material storage section 48 can be fed from the bottom side of the test kiln 31, in other words, from the bottom of the preheater, toward the test kiln 31 through the conveyor 47.

[0099] The evaluation combustion system 30 includes a treatment system for treating the exhaust gas discharged from the cyclone 36. This treatment system includes a cooling tower 37, a bag filter 38, a bag filter 39, a suction fan 42, and a chimney 43. The exhaust gas discharged from the cyclone 36 passes through the cooling tower 37 to be cooled, and then passes through the bag filter 38 to remove dust contained in the exhaust gas.

[0100] Activated carbon from an activated carbon feeder 41 is supplied to the exhaust gas that has passed through the bag filter 38, and some of the components contained in the exhaust gas are adsorbed and removed. The exhaust gas then passes through a bag filter 39, whereupon dust containing activated carbon is removed, after which the exhaust gas is sent to a chimney 43 via a suction fan 42 and released from the chimney 43 into the outside air.

[0101] Test kiln 31 was used with the following specifications: Kiln length: 8,340mm Aspect ratio(L / D): 18.5 ·Fuel used: JIS Class 1 A heavy oil Tilt: 5.0% (2.86°)

[0102] A test was conducted in which each of the raw materials S1 to S16 was supplied from the raw material storage section 35, and was charged into the test kiln 31 from above the preheater through the conveyor 34, and was fired in the test kiln 31. The test conditions were as follows.

[0103] Raw material input: 100kg / h ·Filling rate: 10% ·Heavy oil burning amount: 35L / h~40L / h Firing temperature in test kiln 31: 1,450℃~1,500℃

[0104] The exhaust gas generated when each of the raw materials S1 to S16 was heated under the above conditions was collected in the collection section 52 via the extraction pipe 51 arranged after the bag filter 38. The collected exhaust gas was then measured using a method based on the triplet odor bag method described in the appendix of the Environment Agency Notification No. 63 of 1995. The results are shown in Table 4. The estimated odor index values ​​of the raw materials S1 to S16 in Table 4 are the same as those shown in Table 3. The actual odor index values ​​of the raw materials S1 to S16 in Table 4 are the measured odor index values ​​of the exhaust gas obtained by heating each of the raw materials S1 to S16, expressed as relative values ​​based on the odor index of the raw material R1 in Table 2.

[0105] [Table 4]

[0106] FIG. 6 is a graph plotting the correspondence between the estimated values ​​and the measured values ​​shown in Table 4. According to FIG. 6, it can be seen that there is a high correlation between the odor index measured by actually heating the raw materials using the test kiln 31 and sampling the generated exhaust gas, and the odor index estimated by calculation based on the raw material blend. This shows that the third odor index I 0This shows that the odor of the exhaust gas obtained when the third cement raw material CO is actually heated can be estimated with high accuracy.

[0107] (Verification 4: Evaluation of the effect on odor caused by feeding the blended raw materials from the bottom of the preheater) Next, for the six types of mixed raw materials (S10, S12, S13, S14, S15, S16) whose estimated odor index (relative value) in Table 3 was 1.02 or more, tests were conducted in which the mixed raw materials were burned in the test kiln 31 in the same manner as above, while maintaining the mixing ratio of each mixed raw material and varying the feeding points of the base raw material and the blended raw materials.

[0108] In detail, of the mixed raw materials (S10, S12, S13, S14, S15, S16), the base raw material R1 was fed from the raw material storage section 35 through the conveyor 34 to the test kiln 31 from above the preheater, and the blended raw materials (R4, R5, R6) were fed from the raw material storage section 48 through the conveyor 47 to the test kiln 31 from below the preheater. In other words, in this verification, the mixed raw materials were not fed from the same place, but each raw material was fed from a different place, and the raw materials were heated in a mixed state in the test kiln 31. The conditions are as shown in Table 5 below.

[0109] [Table 5]

[0110] For example, level K10 is similar to raw material S10 in Table 3 in the sense that it is a raw material fed to the test kiln 31, and is a mixture of 85% base raw material R1 and 15% blended raw material R4. However, in this level K10, the base raw material R1 is fed to the test kiln 31 from the top of the preheater, and the blended raw material R4 is fed to the test kiln 31 from the bottom of the preheater, which is different from the verification using raw material S10 shown in Table 3. The same is true for the other levels K12 to K16.

[0111] For these levels K10, K12 to K16, exhaust gas was extracted and the odor index was measured in the same manner as in Verification 3, which obtained the results in Table 4. The results are shown in Table 6. Table 6 also lists the measurement results (see Table 4) for the mixed raw materials corresponding to each level (S10, S12, S13, S14, S15, S16) for comparison.

[0112] [Table 6]

[0113] From Table 6, it was confirmed that when raw materials containing base raw material R1 and blended raw materials (R4, R5, R6) having a higher odor index when burned than base raw material R1 are heated in test kiln 31, the odor index of the exhaust gas is lower when the blended raw materials (R4, R5, R6) are charged from the bottom of the preheater (b) than when the mixed raw materials of the base raw material and the blended raw materials are charged all at once from the top of the preheater (a), regardless of the blended raw materials and blending ratio. This shows that by charging second cement raw material C2, which has a high odor index such as waste, from the bottom of the preheater in step #9, the consumption rate of second cement raw material C2 can be increased while suppressing an increase in the odor of the exhaust gas.

[0114] (Verification 5: Odor index estimation using an odor sensor) The odor of each of the exhaust gases A5 obtained by heating the raw materials R1 to R6 in the verification 1 was measured using an odor sensor (XP-329m manufactured by New Cosmos Electric Co., Ltd.). Specifically, each of the exhaust gases A5 was measured with the odor sensor in the following procedure.

[0115] The odor sensor was started and warmed up for about an hour to stabilize the sensor behavior. After that, the activated carbon tank and the odorless air pump were connected, the pump was turned on and odorless air was filled into the airbag, after which the odorless air in the airbag was sucked into the odor sensor to perform zero and span adjustments. Next, the odor sensor was connected to the airbag in which exhaust gas A5 obtained by heating raw material R1 was sampled, and measurements were started. After confirming that the readings had stabilized, the readings were recorded.

[0116] After removing the airbag containing the flue gas A5 obtained by heating raw material R1 from the odor sensor, an airbag containing odorless air was connected to the odor sensor, and the odorless air in the airbag was sucked into the odor sensor to perform zero and span adjustment. Then, the odor sensor was connected to the airbag containing the flue gas A5 obtained by heating raw material R2, and measurements were started. After confirming that the readings were stable, the readings were recorded. In the same manner, the odor of the flue gas A5 was measured by the odor sensor for each of raw materials R1 to R6. The results are shown in Table 7. The odor sensor measurement values ​​in Table 7 are expressed as relative values ​​based on the measurement values ​​based on the flue gas A5 obtained by heating raw material R1, as with the odor index measurements.

[0117] [Table 7]

[0118] FIG. 7 is a graph plotting the correspondence between the odor index and the odor sensor measurement value shown in Table 7. According to FIG. 7, a strong correlation was observed between the logarithm of the odor sensor measurement value and the odor index measurement value. Based on this result, it can be seen that the odor index can be easily derived from the odor sensor measurement value by using a conversion formula. In other words, in step #12, the first odor index I 1 In deriving the first odor index I, the odor of the exhaust gas A5 obtained by heating the first cement raw material C1 was measured using an odor sensor, and the first odor index I was calculated by applying a conversion formula to the measured value. 1In step #22, the second odor index I 2 The same is true when deriving

[0119] Measuring the odor index using a method based on the triangular comparison odor bag method requires a lot of time and effort. In contrast, measuring odors using an odor sensor allows for quicker and easier measurement than measuring the odor index using a method based on the triangular comparison odor bag method. In addition, it is possible to derive the odor index by applying a prerecorded conversion formula to the measurement value measured using the odor sensor. [Explanation of symbols]

[0120] 1: Cement manufacturing equipment 5: Preheater 5a, 5, 5c, 5d, 5e: Cyclone 6: Cement kiln 7: Burner 10: Odor evaluation device 11: Air pump 11a:Flow meter 12: Nitrogen gas source 12a:Flow meter 13:Heating chamber 13A: Heating environment space 14:Heating mechanism 16: Gas bag 17: Valve 18: Container 21: Raw material input port 22: Raw material input port 30: Evaluation combustion system 31: Test kiln 32: Exhaust duct 33: Burna 34: Conveyor 35: Raw material storage section 36: Cyclone 37: Cooling tower 38: Bag filter 39: Bag filter 41:Activated carbon charging device 42: Suction fan 43: Chimney 47: Conveyor 48: Raw material storage section 51: Air extraction pipe 52: Collection Department A1: Air A2: Nitrogen gas A3: Mixed gas A5: Exhaust gas

Claims

1. A step (a) of preparing information on a first odor index, which is an odor index of an exhaust gas generated when a first cement raw material is heated, and information on a second odor index, which is an odor index of an exhaust gas generated when a second cement raw material made of a material different from the first cement raw material is heated; and (b) estimating a third odor index, which is an odor index of exhaust gas generated when a third cement raw material obtained by mixing the first cement raw material and the second cement raw material is heated, by calculation based on the mixing ratio of the first cement raw material and the second cement raw material, the first odor index, and the second odor index.

2. The first odor index is an odor index of exhaust gas generated when the first cement raw material is heated in a heating environment in a preheater attached to a cement kiln, 2. The method for evaluating an odor of an exhaust gas according to claim 1, wherein the second odor index is an odor index of an exhaust gas generated when the second cement raw material is heated in a heating environment in the preheater.

3. The step (a) A step (a1) of measuring an odor of exhaust gas generated when the first cement raw material is heated using an odor sensor to obtain a first measurement value; (a2) measuring an odor of exhaust gas generated when the second cement raw material is heated using an odor sensor to obtain a second measurement value; 3. The method for odor evaluation of exhaust gas according to claim 1 or 2, further comprising a step (a3) ​​of deriving the first odor index, which is an odor index value corresponding to the first measurement value, and the second odor index, which is an odor index value corresponding to the second measurement value, based on a relative relationship between a measurement value by an odor sensor and an odor index that has been registered in advance.

4. A step (a) of preparing information on a first odor index, which is an odor index of an exhaust gas generated when a first cement raw material is heated, and information on a second odor index, which is an odor index of an exhaust gas generated when a second cement raw material made of a material different from the first cement raw material is heated; a step (b) of estimating a third odor index, which is an odor index of exhaust gas generated when a third cement raw material obtained by mixing the first cement raw material and the second cement raw material is heated, by calculation based on a mixing ratio of the first cement raw material and the second cement raw material, the first odor index, and the second odor index; and (c) comparing an evaluation value based on the third odor index with a predetermined threshold value, and if the evaluation value is equal to or less than the predetermined threshold value, adding the third cement raw material from above a preheater attached to a cement kiln.

5. 5. The method of claim 4, wherein in the step (c), when the evaluation value exceeds the predetermined threshold value, the mixing ratio is changed so that the evaluation value becomes equal to or less than the predetermined threshold value, and then the third cement raw material is charged from an upper part of the preheater.

6. The second odor index is higher than the first odor index, In the step (c), when the evaluation value exceeds the predetermined threshold value, the mixing ratio is changed by decreasing a relative ratio of the second cement raw material to the first cement raw material so that the evaluation value is equal to or less than the predetermined threshold value, and then the third cement raw material is charged from an upper portion of the preheater; 5. The method of claim 4, further comprising the step (d) of feeding the second cement raw material from a lower portion of the preheater.

7. The first cement raw material is a blended raw material blended in a raw material step, 7. The method of claim 6, wherein the second cement raw material is a waste material.

8. the first odor index is an odor index of a gas generated when the first cement raw material is heated in a simulated heating environment in the preheater, 8. The method for using a cement raw material according to claim 4, wherein the second odor index is an odor index of a gas generated when the second cement raw material is heated in the simulated environment.

9. The step (a) A step (a1) of measuring an odor of a gas generated when the first cement raw material is heated using an odor sensor to obtain a first measurement value; (a2) measuring an odor of a gas generated when the second cement raw material is heated using an odor sensor to obtain a second measurement value; 8. The method for using a cement raw material according to claim 4, further comprising a step (a3) ​​of deriving the first odor index, which is an odor index value corresponding to the first measurement value, and the second odor index, which is an odor index value corresponding to the second measurement value, based on a previously registered relative relationship between a measurement value by the odor sensor and an odor index.

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