JP4922908B2 - Moisture content measuring apparatus and moisture content measuring method - Google Patents

Description

  The present invention relates to an apparatus for measuring the amount of water adhering to a granular sample based on the weight of the sample before and after drying, for example, a granular material that performs processing such as granulation, drying, and firing of the granular material This is a technique suitable for use in sampling various granular samples and measuring the amount of water in various plants that handle the above.

  For example, as a method for measuring the moisture content and moisture content of powder samples at sintering factories, coke factories, and raw material yards in steel industry, conventionally, the sample is heated and dried, and the sample before and after the drying. A method of calculating a moisture content from a change in weight (an absolutely dry moisture meter), a method of irradiating a powder sample with electromagnetic waves having different wavelengths, and determining a moisture content by the difference in reflectance (infrared three-wave moisture meter), and A method (neutron moisture meter) or the like for irradiating a powder sample with neutron rays and measuring the moisture content from the attenuation rate is known.

  Among these methods, the moisture content is calculated from the weight of the sample before and after drying, in addition to the method in which the operator collects the sample and manually measures the sample weight before and after drying using a balance etc. Several devices that automatically perform drying processing and weight measurement before and after drying have been proposed as follows.

  In the automatic moisture content measuring device disclosed in Patent Document 1, the powder sample is dispersed in an annular shape on the rotary table by directly dropping the powder sample on the flat surface while rotating the rotary table. And measure. Above the turntable is provided with a plurality of heating and drying means such as a plurality of infrared light bulbs facing the sample dispersed in a cylindrical shape, and below the turntable is provided with a rotation drive mechanism and a weigher, A mechanism for connecting the rotary table only to either the rotary drive mechanism or the weigher is provided. The rotating table is rotated during sample sampling and drying, and connected to the weigher with the rotating table stopped only during weight measurement before and after drying, and the weight of the rotating table and the sample thereon is measured. Like to do. After the measurement is completed, the sample on the rotary table is dropped or scattered from the table by rotating the rotary table at high speed and bringing the scraper plate into contact with the upper surface of the rotary table, so that the sampling operation of the next sample is started. I have to.

  In the automatic moisture measuring device disclosed in Patent Document 2, a sample collecting / metering device and a moisture measuring device are connected by a conveyor device, and a large number of drying dishes (sample dishes) containing sample powder particles are prepared. Then, after the sample powder particles are sequentially collected in each drying dish in the sample collecting / metering device and the initial weights thereof are measured, these are conveyed to the moisture measuring device by the conveyor device. The moisture measuring device includes a rotating gondola-type drying mechanism that can accommodate a large number of drying dishes, a weighing mechanism, a sample recovery mechanism, a drying dish cleaning mechanism, a recovery mechanism, and a robot mechanism. Each drying pan conveyed by the conveyor device is sequentially inserted into the drying mechanism by the robot mechanism. Next, the dried sample is transported to the weighing mechanism together with the drying pan by the robot mechanism and weighed. The tare weight is memorized by dumping outside the dish and cleaning the empty drying dish with the brush of the cleaning mechanism and then weighing the weight of the drying dish with the measuring mechanism. Thereafter, the drying dish is transferred onto the collection mechanism. The drying tray recovery mechanism is for storing a large number of drying dishes, and the drying dishes are transferred to the sample collection / weighing apparatus manually.

  In addition, the moisture measuring device disclosed in Patent Document 3 includes a swivel arm that supports a tiltable sample pan and can be rotated and moved up and down along a horizontal plane. On the circular trajectory, a sample loading unit including a scraper for flattening the surface of the sample in the sample plate, a weighing unit for measuring the sample weight in the sample plate together with the sample plate, and drying for drying and heating. And a sample discharge unit that discharges the sample by inclining the sample pan, and a control unit that controls the rotation and vertical movement of the swivel arm is provided. Measurement is possible. An outline of a measurement processing flow in the moisture measuring apparatus is shown in FIG.

JP 54-24695 A Japanese Utility Model Publication No.59-149046 Japanese Unexamined Patent Publication No. 8-219970

  Among the methods for measuring the moisture content of the granular material sample described above, the method for obtaining the moisture content from the difference in the reflectance of electromagnetic waves having different wavelengths (infrared three-wavelength moisture meter) determines the particle diameter and color of the granular material to be measured. It has a fatal drawback of being affected.

  In addition, the method of measuring moisture content from the decay rate of the neutron beam irradiated to the granular material sample (neutron moisture meter) measures even the crystalline moisture in the granular material. Not suitable.

  On the other hand, the method of obtaining the moisture content from the weight change before and after heating and drying of the granular sample (absolute moisture meter) is primitive compared to the above method, but the sample type, particle size, or measurement atmosphere Regardless of the state, it is possible to accurately and reliably measure the moisture content. However, in this method, when the operator manually performs weight measurement using a balance or the like from sampling of the sample, the type, particle size, moisture, and color of the powder particles change every moment, and multiple types of powder particles When the body is mixed and the blending ratio of multiple powders changes from moment to moment, it is necessary for the operator to perform measurement work such as sampling and weight measurement using a balance etc. The man-hour increases. Further, in a plant that operates continuously for 24 hours, it is necessary to always continue such work. Moreover, since a series of operations such as sample sampling, initial weight measurement, drying process, and post-dry weight measurement is performed for each measurement, it takes 1-2 hours to calculate the moisture content. There was a problem that it was not suitable for management of the moisture content which changes every moment.

  Such a problem is solved to some extent by the technique described in Patent Documents 1 to 3, which is an apparatus that automates the method for obtaining the moisture content from the weight change before and after drying the sample. In principle, the process of sampling and drying the sample is indispensable, and even if the measurement time to calculate the moisture content is shortened, it is limited to about 30 minutes at most. In addition, the time required for drying and preferable conditions often vary depending on the type and state of the granular material. As described above, there is a problem that it is difficult to apply an automated apparatus to a use in which conditions are set more flexibly with respect to changes in the type and state of the powder and a quick response is required.

  In view of the problems of the moisture measuring device of the above-described conventional powder and sample, and determining the moisture content from the weight change before and after heating and drying of the sample, the present invention provides the type, state, and It is an object of the present invention to provide a moisture measuring apparatus and method that can flexibly cope with fluctuations in the blending ratio, and can measure the moisture content of a sample with a shorter measurement time and with higher accuracy.

  The gist of the present invention is as described below.

ただし、
ｔ：時刻
Ｗ（ｔ）：時刻ｔの水分率
Ｔ１、Ｔ２、Ｔ３：予め複数の試料についての水分率Ｗの時間変化の測定値に基づいて、回帰計算を用いて決定されたフィッティング係数 The moisture content measuring apparatus of the present invention uses a powdery particle containing moisture as a sample, measures the time transition of the mass value of the sample while drying the sample, and measures the moisture content or moisture content contained in the sample. A moisture content measuring apparatus, a sample heating unit for heating the sample to dry, a sample weighing unit for weighing the sample and outputting a mass value continuously or intermittently, the sample, and the sample heating The amount of moisture or water content contained in the sample based on a series and a finite number of mass values for a predetermined period of time that are output continuously or intermittently. A weighing data processing unit to calculate, the weighing data processing unit using the finite number of mass values of the series and a predetermined period, the time transition of the decrease in mass value until the sample is completely dried , Or the time transition of the time change of mass Predicted by prediction calculation, is calculated by estimating the amount of moisture or water content contained a sample prior to measurement, the mass values are weighed at predetermined time intervals, predetermined prediction calculation in which the weighing data processing unit performs Calculates the maximum value of the time change amount from the time transition of the time change amount by calculating the difference of the respective mass values at successive times from a finite number of mass values in a predetermined period of time, and based on the maximum value The primary predicted moisture content W1 is calculated from a first prediction formula for predicting the moisture content, which represents the relationship between the moisture content obtained in advance for a plurality of samples and the maximum value of the amount of time change, and the series and predetermined From the difference between the mass value before drying of the sample and the mass value at each time from the finite number of mass values in the period, the time transition of the moisture content of the moisture decreased by drying is calculated, and the calculated moisture content time Based on the transition and the primary predicted moisture content W1, the formula ( ) To calculate the W (t) by setting the Wf value of the formula (1) within a predetermined range using the primary predicted moisture content W1 as a temporary moisture content, and the time transition of the calculated moisture content and comparison wherein the calculation der Rukoto to derive the moisture content Wf by.

However,
t: Time
W (t): Moisture content at time t
T1, T2, T3: fitting coefficients determined in advance using regression calculation based on measured values of the change in moisture content W over time for a plurality of samples

ただし、
ｔ：時刻
Ｗ（ｔ）：時刻ｔの水分率
Ｔ１、Ｔ２、Ｔ３：予め複数の試料についての水分率Ｗの時間変化の測定値に基づいて、回帰計算を用いて決定されたフィッティング係数 The moisture content measurement method of the present invention uses a powdery particle containing moisture as a sample, measures the time transition of the mass value of the sample while heating and drying the sample in a sample heating unit, and the amount of moisture contained in the sample. Alternatively, a moisture content measuring method for measuring a moisture content, wherein a weighing procedure before drying to obtain a mass value before drying by weighing the sample before heating and drying the sample, and heating to dry the sample. A sample drying step, a repeated weighing procedure for weighing a sample and outputting a mass value continuously or intermittently while drying in the sample drying step, and a series and predetermined output of the continuous or intermittent output A moisture content prediction calculation procedure for calculating a moisture content or a moisture content contained in a sample based on a finite number of mass values for a period, and the moisture content prediction calculation procedure is limited to the series and a predetermined period of time. Using a mass value, the sample is completely dry Time course of reduction of the mass values to that, or the time variation of the time course of weight values predicted by a predetermined prediction computation, calculated by estimating the amount of moisture or water content contained a sample prior to measurement The mass values are weighed at predetermined time intervals, and the predetermined prediction calculation performed in the moisture content prediction calculation procedure is a difference between mass values at successive times from a finite number of mass values in a series and a predetermined period. Calculate the maximum value of the time change amount from the time transition of the time change amount by calculation, and represent the relationship between the moisture rate obtained for a plurality of samples in advance and the maximum value of the time change amount based on the maximum value The primary predicted moisture content W1 is calculated from the first prediction formula for predicting the value, and the difference between the mass value before drying the sample and the mass value at each time from a finite number of mass values in a predetermined period. , Calculate the time transition of the moisture content of the moisture decreased by drying, Based on the time transition of the moisture content and the primary predicted moisture content W1, the primary predicted moisture content W1 is set as a temporary moisture content using the formula (1), and the value of Wf in the formula (1) is a predetermined range. in sets to calculate the W (t), and wherein the calculation der Rukoto to derive the moisture content Wf compared to time course of the calculated moisture content.

However,
t: Time
W (t): Moisture content at time t
T1, T2, T3: fitting coefficients determined in advance using regression calculation based on measured values of the change in moisture content W over time for a plurality of samples

  According to the moisture content measuring apparatus and the moisture content measuring method of the present invention, the time transition of the mass value is estimated based on the mass value that is the weighed value of the sample for a certain finite period, and the sample before drying is included. Since the moisture content or moisture content is estimated, it is possible to flexibly cope with fluctuations in the type, state, and blending ratio of powder particles, and with a shorter measurement time and higher accuracy than the conventional method. Can be measured. As a result, compared with the prior art, the moisture content measurement accuracy is hardly lowered, and the time required to obtain the moisture content measurement result can be shortened from 1/2 to 1/3, for example. As a result, it can be applied to the measurement of the moisture content of the sintered blending raw material, which has been impossible until now, and can greatly contribute to the improvement of the yield of the sintering operation and the stable operation.

  Embodiments of the moisture content measuring apparatus and measurement method of the present invention will be described below in detail with reference to the drawings, taking moisture measurement in a sintering process as an upper process of the steel industry as an example. In the sintering process, a powdered iron ore powder ore, a small amount of lime powder and coke powder are mixed to make a sintered blended raw material, and the sintered blended raw material is baked and hardened to a certain size. Agglomerates are made. In the sintering process, the moisture content (or moisture content), which is the amount of moisture contained in the sintering compound material before sintering, greatly affects the sintering process, so it is necessary to measure the moisture content of the sintering compound material in advance. There is.

  In the present embodiment, the sample is a sintered blending raw material that is a raw material of the sintering process. FIG. 1 shows an outline of the configuration of the moisture content measuring apparatus according to the present embodiment. In FIG. 1, the upper part in the square box at the center is a drying chamber 10 which is a space for drying a sample, and the lower part is a weighing chamber 11 for measuring the mass of the sample. The weighing chamber 11 is provided with an entrance for taking in and out the sample 8 (not shown).

  The drying chamber 10 is equipped with a temperature measuring unit 1 that measures the temperature in the room and a sample heating unit 4 that heats the sample to dry it. The sample 8 is placed on the sample pan 7 and dried and weighed. A heating power source 3 for supplying power to the sample heating unit 4 and a heating controller 2 for controlling the heating by the sample heating unit 4 by controlling the heating power source 3 are placed outside the room. The sample heating unit 4 may be constituted by a heating device using radiated light such as an infrared heater or a halogen lamp. In the present embodiment, the power supplied from the heating power source 3 to the sample heating unit 4 is controlled by the heating controller 2 so that the room temperature (that is, the ambient temperature) of the drying chamber 10 is constant.

  In addition to the method for measuring the ambient temperature, the temperature measuring unit 1 may include a light receiving unit that receives the radiated light from the sample heating unit 4 and a method for measuring the temperature of the light receiving unit. As another heating control method, the power supplied to the sample heating unit 4 may be controlled to be constant. At this time, the temperature measuring unit 1 may be omitted.

  Further, by supplying a drying gas such as dry air or nitrogen gas to the drying chamber 10, the sample 8 can be dried quickly. In this case, the sample heating unit 4 may be arranged to heat the drying gas.

The weighing chamber 11 weighs a sample tray 7 for storing the sample 8, a cylindrical sample stage 6 on which the sample tray 7 is mounted in order to measure the mass of the sample 8, and a sample tray 7 for storing the sample. A sample weighing unit 5 is disposed. Since the sample stage 6 becomes a high temperature as the sample 8 is heated and dried, the sample stage 6 may be made of ceramic such as alumina or quartz glass (SiO ₂ ) having excellent heat resistance. Further, the sample weighing unit 5 may be configured using a commercially available electronic balance having a measurement accuracy of high accuracy mg order or μg order depending on the amount of sample to be measured and required measurement accuracy. The upper part of the sample stage 6 protrudes toward the drying chamber 10 through a hole 12 provided between the drying chamber 10 and the weighing chamber 11. In the present embodiment, a sample tray 7 on which a sample 8 is manually loaded is placed on the sample mount 6.

  In addition, with an automated apparatus as described in Patent Documents 1 to 3, the sample 8 is supplied to the sample pan 7 prior to measurement, and the sample 8 is removed from the sample pan 7 after the measurement is completed. Of course it is good. For example, the sintered compounding material is sampled from the entrance of the conveyor for supplying the sintered compounding material to the sintering surge hopper in the sintering factory, and the sampled sample is automatically loaded into the sample pan 7 of the apparatus shown in FIG. The automatic sampling device to be installed may be installed in the moisture content measuring device or installed in the moisture content measuring device (not shown).

  While the sample 8 is heated and dried, the measured value of the sample pan 7 measured continuously by the sample weighing unit 5 is input to the weighing data processing unit 9 installed outside the weighing chamber 11 every moment. . At this time, when the sample weighing unit 5 outputs a digital signal, the weighing data processing unit 9 includes a digital I / O unit, and when outputting an analog signal instead of the digital signal, includes an A / D conversion unit (see FIG. Not shown). The heating controller 2 and the weighing data processing unit 9 are the above-mentioned digital I / O unit or A / D conversion unit, keyboard and mouse input unit, data storage unit composed of HDD and DVD, and a personal computer composed of a display. Can be configured. Further, the weighing data processing unit 9 is provided with a network board for connecting via a network to a process computer that manages the inside of the sintering plant, so that information on the sample 8 and measured moisture content can be transmitted and received. good.

ここで、ｍ（ｔ_ｎ）は時刻ｔ_ｎの試料質量値であり、時間ｔ_ｎ（ｎは自然数）は所定の測定時間の間隔の値Δｔ（例えば１０ｓｅｃ）をとる。当該時間の間隔Δｔは試料８が十分乾燥するのに要する時間、及び試料８の乾燥速度から見て十分短い時間であれば良い。ただし、時間の間隔Δｔが大きすぎると、以下で計算する水分率の測定精度が悪くなる。 The mass value of the sample pan 7 is measured in advance, and the sample weighing unit 5 outputs the mass value of the sample 8 corrected by subtracting the mass value from the weighed value of the sample pan 7 on which the sample 8 is loaded. It is good to do. FIG. 2 schematically shows how the sample mass value m collected by the weighing data processing unit 9 changes with time. 2A and 2B, the horizontal axis represents time t (the drying start time is set to t = 0 for convenience), the vertical axis in (a) is the sample mass value m, and the vertical axis in (b). Represents a time change amount (hereinafter referred to as a time change amount) Δm of the sample mass value m per predetermined time Δt set in advance. The time change amount Δm is calculated by Expression (2).

Here, m _{(t n)} is the sample mass value at time _{t n,} the time _t n (n is a natural number) has a value interval of a predetermined measuring time Delta] t (e.g., 10 sec). The time interval Δt may be a time required for the sample 8 to be sufficiently dried and a sufficiently short time as viewed from the drying speed of the sample 8. However, if the time interval Δt is too large, the measurement accuracy of the moisture content calculated below deteriorates.

The sample mass value in FIG. 2 (a) decreases from the pre-drying mass value m0 as time elapses, and reaches the post-drying mass value m∞ at the stage where the water adhering to the sample 8 has completely evaporated. At this time, the moisture content W (mass%) of the moisture content contained in the sample 8 before drying is obtained by Equation (3).

  On the other hand, as shown in FIG. 2B, the amount of time change Δm per predetermined time Δt gradually increases as the drying of the sample proceeds and reaches a maximum value (hereinafter referred to as Δmp) at time tp. After that, it decreases and eventually becomes a mountain shape that becomes zero.

  Next, a description will be given of processing performed by the weighing data processing unit 9 for deriving the moisture content and moisture content contained in the sample 8 before drying from the sample mass value m obtained by weighing.

  The inventors of the present application use a large number of samples with different types, states, and mixing ratios of raw materials constituting the sintered mixed raw materials for the sintered mixed raw materials that are samples in the sintering process of the steel industry. The pattern of the time transition of the sample mass value m and the time variation Δm was examined in detail so that the drying conditions such as the atmospheric temperature and the atmosphere when the sample was dried were kept substantially constant. Of course, it goes without saying that the mass value m0 before drying, the mass value m∞ after drying, the maximum value Δmp of time variation and the time tp thereof show different values depending on the sample. Based on the results of detailed analysis of the actual data obtained from these sample samples, a method for evaluating the amount of water adhering to the sample described below with high accuracy and in a short time was devised.

  That is, the sample mass value that changes from moment to moment during the sample drying process is continuously or preset by the sample weighing unit 5 while keeping the drying conditions such as temperature and atmosphere when drying the sample substantially constant. Measurement is performed at an interval Δt (for example, 10 sec). Next, using the sample mass value, the sample mass value and the sample mass change amount Δm (time change amount) per predetermined time Δt are used, and future values of the sample mass and time change amount are described in detail below. As will be described below, the estimation is performed by a predetermined prediction calculation procedure. Using the result of the prediction calculation, the moisture content W adhering to the sample is accurately predicted.

  By estimating the moisture content W of the sample using the prediction calculation in this way, the measurement accuracy of the moisture content W is not reduced as compared with the conventional method, and based on the mass of the sample of the prior art before and after drying. Thus, the measurement time can be reduced from 1/2 to 1/3, for example, compared to the measurement time of the method of measuring the moisture content.

  FIG. 3 shows an outline of an example of a measurement procedure of the moisture content measuring apparatus according to the present embodiment.

S100: Sample sampling procedure Using an automatic sampling device, the sintered compounding material is sampled by an amount of about a preset volume or mass from an outlet provided in a conveyor for conveying the sintered compounding material. Then, the sampled sample 8 is automatically put into the sample pan 7. In the above description, the sample is put into the sample tray 7 for each sample. However, it is also possible to load the sample separately on the sample tray 7 and replace the sample pan with the weighing chamber 11.

S101: Weighing procedure before drying The sample weighing unit 5 weighs the input sample 8, and outputs it to the weighing data processing unit 9 as the mass value m0 of the sample 8 before drying. The weighing data processing unit 9 outputs the mass value m0 before drying. Remember. Here, an example in which the sample weighing unit 5 has a function of subtracting the mass of the sample pan 7 from the weighed value and outputting the pre-drying mass value m0 of the sample 8 is shown.

S102: Start of Sample Drying Step The heating power source 3 is turned on by the heating controller 2, the sample heating unit 4 starts heating the sample 8, and the sample drying step for drying the sample 8 is started.

S103: Repeated weighing procedure While continuing to dry the sample, the sample weighing unit 5 weighs the sample 8 and outputs the mass value m, for example, every 10 seconds, and the weighing data processing unit 9 m is stored in association with the weighing sequence number or measurement time. This is repeated until the prediction calculation start timing _tmax is reached. Note that the weighing itself may be either continuous in time or intermittent. The time management for weighing may be performed by the weighing data processing unit 9. The prediction calculation start timing _tmax may be set to a fixed value such as 10 minutes in advance, or two mass values measured continuously, that is, m (t _{n + 1} ) and m (t _n ). May be set as a time when the difference (ie, | m (t _{n + 1} ) −m (t _n ) |) becomes smaller than a sufficiently small value set in advance. Alternatively, the prediction calculation start timing t _max may be determined using the difference being normalized and | m (t _{n + 1} ) −m (t _n ) | / m (t _n ). In this way, a finite series of mass values is obtained for a predetermined period that is sufficiently shorter than until it is completely dry. The weighing operation by the sample weighing unit 5 is preferably controlled by the weighing data processing unit 9. In the above description, the weighing is performed at a constant cycle. However, the weighing data processing unit 9 may store the weighing time and the weighing value at that time by repeatedly weighing at a substantially constant time interval.

S104: When the time from moisture ratio prediction algorithm dry start to reach the prediction calculation start timing _{t max,} (here n 0,1, ···, max) mass value m _(t n) which stores far the In the weighing data processing unit 9, the prediction calculation described in detail below is performed, and the moisture content W of the sample 8 is calculated.

S105: Drying end procedure On the other hand, when the prediction calculation start timing is reached, the weighing of the sample 8 by the sample weighing unit 5 is terminated under the time management of the weighing data processing unit 9, and the heating power source 3 is turned on by the heating controller 2. The sample heating unit 4 is turned off, heating of the sample 8 by the sample heating unit 4 is finished, and the sample 8 on the sample dish 7 is discharged using an automatic sampling device. Then, as a preparatory work for weighing the next sample, the sample tray 7 is cleaned using an air jet or the like.

  Next, the first moisture content prediction calculation executed by the weighing data processing unit 9 will be described in detail.

First prediction for estimating the water content W0 based on the mass value m (t _n ) measured for the sample 8 (where n is 0, 1,..., Max) and deriving the moisture content of the sample 8 FIG. 4 is a diagram for explaining the principle of the method. The horizontal axis represents the time t after the start of drying of the sample, and the vertical axis represents the time variation Δm of the sample. Here, a case where the sample is weighed at a constant time interval will be described. In the course of drying the sample, after the amount of time change once reaches the maximum Δmp, the time change amount becomes a predetermined value (hereinafter referred to as ΔMA (ΔMA <Δmp)) or less (hereinafter referred to as ta) in advance. Based on the value of the time change amount in a predetermined period (hereinafter referred to as TA), a transition of the time change amount after time ta + TA is predicted and calculated.

ここで、Ａ、Ｂ、Ｃはフィッティング係数である。このように、Δｍの予測式を時間ｔの２次式としたとき、時間ｔが無限大で発散して零とはならない。そこで、時間ｔのとり得る最大値ｔｃｒｓを予め設定しておいて、そのときにΔｍの値を零としておく。 In this prediction calculation, a quadratic expression represented by Expression (4) is used as an example of a prediction expression representing a transition of the time change amount, and each coefficient of the prediction expression is a mass value m (t measured for the sample 8 _n ) (where n is 0, 1,..., max), and is derived from the measured value of the time variation Δm using the least square method.

Here, A, B, and C are fitting coefficients. Thus, when the prediction formula of Δm is a quadratic expression of time t, time t is infinite and diverges and does not become zero. Therefore, the maximum value tcrs that the time t can take is set in advance, and the value of Δm is set to zero at that time.

ここで、Ｄ、Ｅ、ｔｘはフィッティング係数である。 Further, the prediction expression representing the transition of the time change amount may be an expression that exponentially depends on the time t represented by Expression (5). The fitting coefficient may be obtained by regression calculation from the measured value of the time variation Δm at each time t.

Here, D, E, and tx are fitting coefficients.

  Note that the prediction formula representing the transition of the time change amount is an expression that can approximate the time transition of the time change amount Δm with a desired accuracy, other than the formulas (4) and (5). I just need it.

ここで、ｔｍａｘは予測区間の終端の時刻であり、数式（４）でΔｍを予測するときには上記のｔｃｒｓ、数式（５）でΔｍを予測するときには∞とすると良い。 Next, the amount of water W0 contained in the sample is the sum of the amount of time change Δm from the start to the end of drying, and is the portion surrounded by the Δm curve and the time axis (horizontal axis) in FIG. It is obtained by calculating the area, and is expressed by Equation (6).

Here, tmax is the time at the end of the prediction interval, and is preferably set to tcrs when the Δm is predicted by the formula (4), and ∞ when the Δm is predicted by the formula (5).

Furthermore, the estimated value of the ratio of the water content W0 included in the sample 8 before drying, that is, the estimated water content W _f1 (mass%) can be calculated by Equation (7).

The data processing for deriving the water content W0 and moisture rate estimated value W _f1 from mass values m and contained the sample weighed obtained was Sample 8, when configuring the weighing data processing unit 9 by a personal computer, A computer program that executes processing to be calculated using each of the above equations is created and installed in the personal computer.

  The results of obtaining the moisture content and moisture content for 88 samples of the sintered blending raw material using the first predictive calculation method are as follows. Whereas the average measurement time of the conventional method for determining moisture from the mass change before and after sample drying is 16 minutes (only pure drying time, excluding sample sampling time and sample discharge time before and after), this implementation In the method for measuring the amount of moisture in the form, the average calculation time was 11 minutes, and the time was reduced by about 32%. In addition, the difference between the conventional method and the present method was very good because all 88 samples were 0.1% or less.

  Since the first prediction method uses data in a region where the drying process has progressed considerably, the drying conditions are stable, and only the sample mass change amount per predetermined time in the monotonically decreasing region is used, a simple prediction equation can be used for error. Is small and can be calculated in a short time. In addition, there is an advantage that work such as preparation of a calibration curve in advance is unnecessary.

  Next, the second moisture content prediction calculation will be described in detail.

FIG. 5 illustrates the principle of the second predictive calculation method for estimating the moisture content W based on the mass value m (t _n ) measured for the sample 8 (where n is 0, 1,..., Max). It is a figure for doing. The horizontal axis of FIG. 5A represents the maximum sample mass change amount Δmp (peak value), and the horizontal axis of FIG. 5B represents time t. The vertical axis represents the moisture content W in both FIGS. The second predictive calculation method is based on this new knowledge that “the maximum sample weight change amount Δmp per predetermined time Δt has a strong correlation with the required water content”. It is used for.

測定時には試料８の時間変化量の最大値Δｍｐを基にして、数式（８）を用いて仮の水分予測値として一次予測水分率Ｗ１を求める。 Calibration curves as shown in FIG. 5 (a) are obtained in advance for a large number of samples of sintered blending raw materials. From this calibration curve, it is assumed that the relationship between the moisture content W and the time variation Δmp is expressed by the equation (8), with the moisture content W at this time as the primary predicted moisture content (hereinafter referred to as W1).

At the time of measurement, based on the maximum value Δmp of the time change amount of the sample 8, the primary predicted moisture rate W1 is obtained as a temporary moisture predicted value using the formula (8).

ここで、Ｗｆは実質的に十分試料が乾燥して得られた水分率の実測値、又、Ｔ１、Ｔ２、Ｔ３はフィッティング係数である。 On the other hand, as a time change W (t) of the moisture content when dried, a prediction formula representing a time change of the moisture content represented by Formula (1) including T1, T2, and T3 as fitting coefficients is assumed. And based on the measured value of the time change of the moisture content W about the sample of many sintering compounding raw materials, a fitting coefficient (T1, T2, T3) is determined using regression calculation beforehand.

Here, Wf is an actually measured value of the moisture content obtained by substantially fully drying the sample, and T1, T2, and T3 are fitting coefficients.

Next, after detecting the maximum value Δmp of the time change amount of the sample 8, the time transition W _mes (t) ((m0− m (t)) / m0) is continuously calculated at predetermined time intervals. Based on the time transition W _mes (t) of the moisture content, using W1 obtained from the above equation (8), the value of Wf in the equation (1) in the range of W1 ± 1.0% in increments of 0.1%. Set. Then, by comparing the 21 curves obtained by substituting Wf in the above formula (1), a curve having a similar time transition is selected, and the moisture content of the sample 8 is determined by the value of Wf of the curve. Estimated. That is, when the time t is increased, the moisture content at which the predicted moisture content transition curve asymptotically becomes the final moisture content that is the moisture content of the sample 8.

  Data processing for deriving the moisture content in the second predictive calculation method described above was realized by software in the weighing data processing unit 9. The prediction results of the moisture content obtained from the sintered blending raw material sample (88 samples) are as follows. The average measurement time of the conventional method for obtaining moisture from the mass change before and after the sample drying was 16 minutes, whereas the average calculation time was 7 minutes, which was a significant time reduction of about 53%. As for the prediction error, 86 cases satisfied the target of 0.1% or less, but 2 cases did not satisfy 0.1%.

  Since this second prediction calculation method can be used for prediction calculation from mass change data immediately after the start of drying, drastic reduction in prediction time can be expected. On the other hand, it is necessary to create a calibration curve in advance, the accuracy of the created calibration curve greatly affects the accuracy, and it is also necessary to create a calibration curve each time the raw material composition changes significantly. In the implementation, it is important to prepare by measuring the water content with a sufficiently high accuracy using a large number of samples.

In addition, it replaces with the method of setting 21 curves previously using said Numerical formula (1), It replaces with the time transition _Wmes (t) of the moisture content which is a measured value, and was calculated _| required from Numerical formula (8). Wf may be predicted and estimated by performing regression calculation as an initial value of the moisture content for obtaining the predicted moisture content W1. Although this method has a larger calculation load than using 21 curves, it is possible to improve the accuracy of detection of the moisture content obtained as a result.

  In the description of the above two prediction methods, the time interval Δt for weighing the sample 8 is constant, but it is not necessarily constant. When the time interval fluctuates, the mass data m (t) measured at time t is temporarily stored in the weighing data processing unit 9, and in order to remove the influence of the fluctuation of the time interval of each mass value data, a predetermined value is used. The time change amount Δm of the sample mass value m per time Δt is calculated by normalizing to a change amount per unit time, for example, 1 second, 10 seconds or 1 minute, instead of the one represented by the formula (2). Good.

  Both of the above two prediction methods are constructed in the weighing data processing unit 9 and may be used by appropriately switching depending on the use, and since accurate moisture content measurement values can be obtained in a short time, It can be expected to contribute greatly.

  As described above, the heating controller 2 and the weighing data processing unit 9 can be configured separately or by the same computer system. The computer system is preferably composed of a CPU, an external storage device such as a HDD, an input / output device such as a keyboard and a mouse, and a computer display. Further, the present invention is made by creating a computer program for causing the computer system to execute a series of processes for deriving the moisture content from the weighing of the sample described in S100 to S105, and loading the computer program into the main storage device for execution. The moisture measuring device and the moisture measuring method may be embodied.

  In the above, the moisture measuring device and the moisture measuring method of the present invention have been described in detail, taking as an example the measurement of the moisture content and moisture content of the sintered blending raw material in the sintering process, which is the upper process of the steel industry. The moisture measuring device and moisture measuring method can be applied not only to the steel industry, but also to a moisture measuring device and moisture measuring method for measuring the moisture content of raw materials of powders and lumps in food manufacturing, chemical manufacturing, etc. Obviously.

  The present invention can be applied to the measurement of the amount of water adhering to a granular sample.

It is a figure which shows the outline of embodiment of the moisture content measuring apparatus of this invention. It is a schematic diagram which shows the time change of a sample mass value, (a) is a graph which shows the time transition of the sample mass value during drying, (b) shows the time transition of the amount of change of the sample mass value per unit time during drying. It is a graph. It is a flowchart which shows the outline of the measurement procedure in embodiment of the moisture content measuring apparatus of this invention. It is explanatory drawing of the 1st prediction method concerning this invention. It is explanatory drawing of the 2nd prediction method concerning this invention, (a) is a graph which shows the relationship between (DELTA) mp and primary predicted moisture content W1, (b) is how to obtain | require final predicted moisture content Wf from primary predicted moisture content W1. It is a graph which shows the outline | summary. It is a flowchart of the process which measures the water | moisture content of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Temperature measurement part 2 Heating controller 3 Heating power supply 4 Sample heating part 5 Sample weighing part 6 Sample mounting stage 7 Sample pan 8 Sample 9 Weighing data processing part 10 Drying room 11 Weighing room

Claims (2)

A moisture content measuring device that measures the time transition of the mass value of a sample while drying the sample with a powdery granule containing moisture as a sample, and measures the moisture content or moisture content contained in the sample,
A sample heating section for heating the sample to dry;
A sample weighing unit for weighing the sample and outputting a mass value continuously or intermittently;
A housing for housing the sample, the sample heating unit, and the sample weighing unit;
A weighing data processing unit that calculates the moisture content or moisture content contained in the sample based on a finite number of mass values of a series and a predetermined period output continuously or intermittently; and
The weighing data processing unit uses the finite number of mass values in the series and a predetermined period, the time transition of the decrease in the mass value until the sample is completely dried, or the time transition of the time variation of the mass value Is estimated by a predetermined prediction calculation, the moisture amount or moisture content that the sample contained before measurement is estimated and calculated ,
The mass value is weighed at a predetermined time interval,
The predetermined prediction calculation performed by the weighing data processing unit is:
From the series and a finite number of mass values for a predetermined period, the maximum value of the time change amount is calculated from the time change of the time change amount by the difference calculation of the respective mass values at successive times,
Based on the maximum value, the primary predicted moisture content W1 is calculated from the first prediction formula for predicting the moisture content, which represents the relationship between the moisture content obtained for a plurality of samples in advance and the maximum value of the time change amount,
From the difference between the mass value before drying of the sample and the mass value at each time from a finite number of mass values in the series and a predetermined period, the time transition of the moisture content of moisture reduced by drying is calculated,
Based on the time course of the calculated moisture content and the primary predicted moisture content W1, the primary predicted moisture content W1 is set as a temporary moisture content using Equation (1), and the value of Wf in Equation (1) is set to a predetermined value. set the range to calculate the W (t), the calculated moisture content of the time transition and water content measuring device Ru calculation der to derive the moisture content Wf compared.

However,
t: Time
W (t): Moisture content at time t
T1, T2, T3: fitting coefficients determined in advance using regression calculation based on measured values of the change in moisture content W over time for a plurality of samples Moisture that measures the moisture content or moisture content of the sample by measuring the time transition of the mass value of the sample while heating and drying the sample with a sample heating unit using the powdery granule containing moisture as a sample A quantity measuring method,
A pre-drying weighing procedure to obtain a pre-drying mass value by weighing the sample before heating and drying the sample;
A sample drying step of heating to dry the sample;
While weighing in the sample drying step, the sample is weighed repeatedly and the weighing value is output continuously or intermittently.
A moisture content prediction calculation procedure for calculating a moisture content or a moisture content contained in the sample based on a series and a finite number of mass values of a predetermined period that are output continuously or intermittently;
The moisture content prediction calculation procedure uses the finite number of mass values in the series and a predetermined period, the time transition of the decrease in mass value until the sample is completely dried, or the time of the time change amount of the mass value Predicting the transition with a predetermined prediction calculation, calculating the moisture content or moisture content that the sample contained before measurement,
The mass value is weighed at a predetermined time interval,
The predetermined prediction calculation performed in the moisture content prediction calculation procedure is:
From the series and a finite number of mass values for a predetermined period, the maximum value of the time change amount is calculated from the time change of the time change amount by the difference calculation of the respective mass values at successive times,
Based on the maximum value, the primary predicted moisture content W1 is calculated from the first prediction formula for predicting the moisture content, which represents the relationship between the moisture content obtained for a plurality of samples in advance and the maximum value of the time change amount,
From the difference between the mass value before drying of the sample and the mass value at each time from a series of finite mass values for a predetermined period, calculate the time transition of the moisture content of moisture reduced by drying,
Based on the time transition of the calculated moisture content and the primary predicted moisture content W1, the value of Wf in Equation (1) is set to a predetermined value using the primary predicted moisture content W1 as a temporary moisture content using Equation (1). A water content measurement method which is an operation for calculating W (t) by setting in a range and deriving the water content Wf by comparing with the time transition of the calculated water content.

However,
t: Time
W (t): Moisture content at time t
T1, T2, T3: fitting coefficients determined in advance using regression calculation based on measured values of the change in moisture content W over time for a plurality of samples

Images