JP2000225302A - Method for estimating parameter for particle distribution, production of particle, and apparatus to be employed therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of automatically and continuously estimating the parameters for particle distribution such as the average particle diameter of a crystal to be produced in a crystallization can, the ratio of existing microcrystals, and the existence ratio of existing large crystals at high precision and to provide an economical apparatus for the estimation. SOLUTION: While time-series data of the quantity of transmitted light and the quantities of forth and back scattered light is obtained a particle state detector 6 by radiating light to a slurry solution taken out by a product taking pump in a crystallization apparatus using a crystallization can 1, the data of slurry concentrations in the crystallization can and a circulation line. The parameters for particle diameter distribution are estimated by carrying out computation using (either totally or partly) the above defined data and also various kinds of data such as the rotation speed of a stirring apparatus 9, the current value of a circulation pump 4, the input and output temperature of a heater in the circulation line, the pressure in the gas phase in the crystallization can, etc., as process data relevant to the crystallization can.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique and an apparatus for estimating the average particle diameter, the abundance of fine particles, and the abundance of large particles produced by an apparatus for producing particles, and to the production of particles using these techniques. In particular, the present invention relates to a method and an apparatus suitable for estimating the particle size of crystals produced by a crystallization step in a crystallization apparatus, and to producing particles using these.

[0002]

2. Description of the Related Art Ammonite, nitrite, ammonium sulfate, sodium chloride,
In the crystallization process represented by, for example, the concentration in the can, the crystal grain size distribution in the can,
Because continuous vibration phenomena such as product crystal grain size distribution occur,
In the crystal production operation using a crystallizer, it is important to grasp the particle size distribution information such as the product particle size and reflect it in the operating conditions in order to improve the acquisition rate of crystals having a desired particle size and shape.
Automatic measurement methods for the product particle size include a measurement method based on physical phenomena using the absorption characteristics of ultrasonic waves according to the particle size, and the amount of transmitted light, the amount of scattered light, the amount of absorbed light, and the amount of scattered light with respect to the irradiation light to the product slurry. There is known a measurement method in which real-time data such as the amount of transmitted light is multiplied by a conversion coefficient calculated in advance by comparing it with test data such as manual analysis.

[0003]

However, since the former is very expensive, it is often difficult to adopt it. Although the latter is less expensive than the former, its estimation accuracy was not sufficient. In the present situation, in many cases, the product is extracted from the crystallizer via a product slurry extraction line, and the particle size of the product after solid-liquid separation is often manually analyzed by a hand sieve or the like. However, since the above-described waving cycle is generally several hours to several tens of hours, the hand analysis must be performed at a frequency of every two hours or every four hours. In addition, since the hand analysis values are discrete values, it is difficult to promptly reflect the values on driving, which may lead to a delay in treatment. In addition, it is difficult to automate the operation by manual analysis of the particle size distribution measurement. From the above, the average particle size of the crystal produced in the crystallizer, fine crystal abundance, feature amount of the particle size distribution such as the large crystal abundance, technology to continuously and accurately estimate automatically and accurately An inexpensive device has been desired.

Estimation is performed by multiplying optical real-time data, such as the amount of transmitted light, the amount of scattered light, and the amount of absorbed light, with respect to the irradiation light on the product slurry, by a conversion coefficient calculated in advance by comparing it with verification data such as manual analysis. In the conventional particle size measuring method, the amount of measurement such as the amount of transmitted light, the amount of scattered light, and the amount of absorbed light is
Not only the particle size distribution but also the crystal slurry concentration is affected. In addition, the hand analysis data for verification is usually obtained by hand sieving the product after passing through the solid-liquid separator. Is partly discharged to the filtrate side, so that the particle size distribution analyzed by hand is different from the crystal particle size distribution captured by the device for detecting optical data based on the above principle installed in the product extraction line. From the above, it is considered that sufficient accuracy of hand analysis granularity estimation cannot be obtained only by conversion from real-time data of a device that detects optical data based on the above principle.

[0005]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems. As a result, optical real-time data obtained by irradiating the liquid containing the particles with light,
The present inventors have found that the above-described problem can be solved by combining with other specific data, and arrived at the present invention.
That is, the present invention provides (1) in the production of particles including a step of growing particles in a liquid, irradiating the liquid containing the particles with light, and scattering light, transmitted light, and absorbed light with respect to the irradiated light. A method for estimating a characteristic amount of a particle size distribution, wherein an arithmetic processing is performed using one or more data and process data of an apparatus for growing particles, (2) including a step of growing particles in a liquid In the production of particles,
A characteristic amount of a particle size distribution, in which a liquid containing particles is irradiated with light, and arithmetic processing is performed using one or more time-series data of scattered light amount, transmitted light amount, and absorbed light amount with respect to the irradiated light. Estimation method,

(3) In the production of particles including a step of growing particles in a liquid, the liquid containing the particles is irradiated with light, and at least one of a scattered light amount, a transmitted light amount, and an absorbed light amount with respect to the irradiated light. And (4) a method for producing particles including a step of growing particles in a liquid, the method comprising an operation of performing an arithmetic process using the data of (1) and process data of an apparatus for growing particles. Irradiating the liquid containing the particles with light, and performing an arithmetic process using one or more time-series data of the amount of scattered light, the amount of transmitted light, and the amount of absorbed light with respect to the irradiated light, the particles comprising: Manufacturing method,

(5) An apparatus which can be used for producing particles including a step of growing particles in a liquid, wherein the liquid containing the particles is irradiated with light, and the amount of scattered light and the amount of transmitted light with respect to the irradiated light An apparatus capable of performing arithmetic processing using one or more data of the absorbed light amount and process data of an apparatus for growing particles, (6) production of particles including a step of growing particles in a liquid A device that can be used for irradiating a liquid containing particles with light and performing arithmetic processing using one or more time-series data of scattered light, transmitted light, and absorbed light for the irradiated light. Equipment capable of

(7) An apparatus which can be used for producing particles including a step of growing particles in a liquid,
(I) means for irradiating the liquid containing the particles with light and obtaining at least one of a scattered light amount, a transmitted light amount and an absorbed light amount with respect to the irradiated light; and (ii) the scattered light amount and the transmitted light amount And means capable of performing arithmetic processing using one or more time-series data of the absorbed light amount,

(8) An apparatus which can be used for producing particles including a step of growing particles in a liquid,
(I) means for irradiating the liquid containing the particles with light and obtaining at least one of a scattered light amount, a transmitted light amount and an absorbed light amount with respect to the irradiated light; (ii) process data of an apparatus for growing particles And (iii) means for performing arithmetic processing using one or more of the scattered light amount, transmitted light amount, and absorbed light amount and the process data. .

The characteristic amount of the particle size distribution as used herein refers to the average particle diameter, the abundance of particles having a size smaller than a predetermined size, or the abundance of particles having a size larger than a predetermined size. Estimating one or more of them corresponds to estimating the feature amount of the particle size distribution. The arithmetic processing refers to calculating the characteristic amount of the particle size distribution by using a regression equation obtained in advance based on each data described above.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus used in the present invention preferably has at least the following items a) to d). A) A particle generating apparatus having a line for extracting generated particles.
B) A device that irradiates a liquid containing particles with light and detects at least one optical amount among a transmitted light amount, a reflected light amount, and an absorbed light amount. C) The means for detecting the process data described above. D)
A device for calculating and processing the characteristic amount of the particle size distribution using the data of (a) and (c). In the method using only real-time data of the optical data detector as in the prior art described above, the product crystal particle size distribution such as product crystal average particle diameter, product crystallite abundance, product large crystal abundance is sufficiently accurate. The present invention has been able to estimate the characteristic amount of the product crystal particle size distribution accurately by a regression equation by adding new information, while an apparatus incorporating this estimation function. Can be provided.

For example, when the present invention is applied to the production of particles by a crystallization step in which crystals are obtained by precipitating crystals from a solution, the product crystal average particle diameter, the product crystallite abundance, the product large crystal presence As an explanatory variable of the regression equation for estimating the characteristic amount of the product crystal grain size distribution such as the rate, the slurry liquid is irradiated with light to the product slurry liquid extraction line from the crystallizer to transmit light, scatter light, and absorb light. By installing a device that detects optical data such as the amount of light, and adding not only the optical real-time data obtained from the device but also one or both of the following two items, the characteristics of the product crystal grain size distribution The accuracy of the quantity estimation can be improved.

One of them is to use process data of an apparatus for growing particles. In the present invention, the process data of the apparatus refers to data including information on the solid concentration in a liquid or the amount of fine particles having a predetermined particle size or less in the liquid. For example, in the case of producing particles by crystallization, it is possible to use data of at least one of the slurry concentration in the crystallization can and the slurry concentration in the external circulation line. Preferably, both are used. Because those data are correlated with the slurry concentration and the amount of microcrystalline particles below a given particle size, by adding these information,
The influence of the slurry concentration in the crystallization can and the amount of microcrystals can be corrected from the optical data obtained from the device that irradiates the slurry liquid with light and detects optical data such as the amount of transmitted light, the amount of scattered light, and the amount of absorbed light. It is. Still more preferably,
Some of the process data around the crystallizer can also be used. The process data around the crystallizer here means, specifically, the rotation speed of the stirrer, the current value of the circulation line pump, each temperature of the circulation line heater, the classification flow rate, the product slurry withdrawal flow rate, the circulation line heater heating medium flow rate, It refers to the temperature inside the crystallizer and the gas phase pressure inside the crystallizer.

The other is to use not only real-time data of the device for detecting the optical data but also time-series data thereof. Generally, in the crystallization process,
As described above, a waving phenomenon such as a particle size distribution in the crystallization can occurs. In the waving phenomenon, when the average particle size in the crystallization can is on the rise, the amount of microcrystals separated from crystals in the can called secondary nuclei increases, and the time during which the average particle size in the can becomes maximal is increased. Shortly before, the amount of microcrystals reaches a maximum. That is, in the time trend of the amount of microcrystals in the can and the average particle size in the can,
The phase of the amount of microcrystals in the can slightly precedes the phase of the average particle size in the can. The phase of the variation in the particle size distribution of the product crystal is synchronized with the phase of the variation in the particle size distribution in the crystallizer. For this reason, if dynamic information such as the average particle size in the can is increasing and decreasing is incorporated into the regression equation for estimating the characteristic amount of the product crystal particle size distribution, the information on the amount of fine crystal particles smaller than a predetermined particle size can be enhanced. In addition, it is possible to improve the accuracy of the feature value estimation value of the product crystal grain size distribution. The time series data just gives dynamic information of the average particle diameter in the can.

The method for producing the particles of the present invention including the step of estimating the characteristic amount of the particle size distribution by the above-described method for estimating the characteristic amount of the product crystal particle size distribution can employ a known method other than this step. Specifically, for example, data of transmitted light amount and scattered light amount obtained by a device installed on a crystallizer product crystal extraction line and irradiating the slurry liquid with light to detect optical data, and a crystallizer can This is the case with a crystallizer including a step of estimating the average crystal grain size of a product by the method of the present invention using process data such as the internal slurry concentration.

[0016]

EXAMPLES The present invention will be described more specifically with reference to the following examples. (Embodiment 1) FIG. 1 is a view schematically showing an example of an apparatus capable of performing an ammonium sulfate crystallization process using the present invention. Ammonium sulfate crystals were produced by crystallization of ammonium sulfate using the apparatus shown in FIG. 1, and the weight-based crystal average particle size after solid-liquid separation was estimated.

Installed in a product slurry extraction line,
The apparatus (6) for irradiating the slurry liquid with light to detect the optical data of the amount of transmitted light and the amount of scattered light provides data of the amount of transmitted light, the amount of forward scattered light, and the amount of backscattered light. From the slurry concentration meter (7) installed at the heater inlet of the external circulation line (2), the slurry concentration data of the external circulation line is obtained, and the slurry concentration meter (8) installed in the crystallization can (1) is obtained. ) Gives data on the slurry concentration in the crystallization can. In addition, the process data around the crystallization can include stirrer (9) rotation speed, circulation pump (4) current value, circulation line heater input / output temperature, classification flow rate, product slurry extraction flow rate, circulation line heater heating medium flow rate Many data can be used, such as the temperature inside the crystallization can, the pressure in the gas phase inside the crystallization can. In this embodiment, the time series data of the forward scattered light amount and the back scattered light amount obtained from the apparatus that irradiates the slurry liquid with light to detect optical data, the slurry concentration in the crystallization can, the slurry concentration in the circulation line, A regression equation for estimating the weight-based average crystal grain size after solid-liquid separation was obtained using various kinds of real-time data.

That is, as the explanatory variables of the average particle diameter estimation formula, time series data of the forward scattered light amount and the back scattered light amount obtained from the apparatus for irradiating the slurry liquid with light and detecting the optical data, Slurry concentration, circulation line slurry concentration, and other real-time process data are used. FIG. 2 shows the change over time of the estimated value of the average particle size based on the weight of the crystallized crystals according to Example 1 by a solid line. Shown by solid line (b)
The correlation coefficient between the estimated value of the weight-based average crystal grain size and the (a) hand analysis value indicated by the dotted line is about 0.8, and a good estimation result is obtained.

(Comparative Example 1) FIG. 3 shows the same as the estimated value of the crystal grain weight-based average particle diameter based on only real-time data of the amount of backscattered light obtained from the apparatus for irradiating the slurry liquid with light and detecting optical data. 3 shows a comparison of hand analysis values. Among the data of transmitted light amount, forward scattered light amount, back scattered light amount, forward scattered light amount ら れ る transmitted light amount obtained from the device that detects optical data for irradiation light, the back scattered light amount and hand It is a comparison with the analysis value, and the solid line (d)
Shows the estimated value based on the amount of backscattered light, and the dotted line (c) shows the result of manual analysis. The correlation coefficient between the two is about 0.65, and the method of the present invention is clearly superior.

FIG. 4 shows an example of the configuration of the apparatus of the present invention.
A data input part for taking in the transmitted light amount, the scattered light amount data and the process data obtained from a device for irradiating the slurry liquid with light and detecting the optical data to a personal computer or a DCS (distributed control system); A part that is stored at regular intervals as time-series data, a part that uses the time-series data and real-time process data to calculate the characteristic amount of the crystal grain size distribution of the crystallized product by regression equation calculation, and a crystal grain such as the average particle diameter And a portion for displaying diameter information. These can be mounted on a DCS, a personal computer, a PLC (programmable logic controller), or the like. Further, applying the estimation result to crystallization control is one of the further utilization methods.

[0021]

According to the present invention, the weight-based average crystal grain size after solid-liquid separation can be accurately estimated online as real-time continuous data. Further, according to the present invention, not only the fine adjustment of the crystallization process operation can be performed, but also the frequency of the particle size distribution measurement by the hand sieve can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an example of an apparatus capable of performing an ammonium sulfate crystallization process using the present invention.

FIG. 2 is a diagram showing a comparison between a temporal change of an estimated value of a crystal grain weight-based average particle diameter according to Example 1 and a manual analysis value.

FIG. 3 is a graph showing a comparison between a crystallized crystal weight-based average particle diameter estimated value based on only real-time data of the amount of backscattered light obtained from an apparatus for irradiating light to a slurry liquid and detecting optical data and the same analysis value.

FIG. 4 is a diagram showing an example of the configuration of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Crystallizer 2 ... External circulation line 3 ... Heat exchanger 4 ... Circulation pump 5 ... Product extraction pump 6 ... Optical particle size property detector 7 ... Circulation line slurry concentration meter 8 ... Slurry concentration meter in a crystallization can 9 … Stirrer 10… Raw material liquid supply

Claims (8)

[Claims] In the production of particles including a step of growing particles in a liquid, the liquid containing the particles is irradiated with light, and at least one of a scattered light amount, a transmitted light amount, and an absorbed light amount with respect to the irradiated light. A method for estimating a feature amount of a particle size distribution, wherein arithmetic processing is performed using data and process data of an apparatus for growing particles. 2. In the production of particles including a step of growing particles in a liquid, the liquid containing the particles is irradiated with light, and at least one of a scattered light amount, a transmitted light amount, and an absorbed light amount with respect to the irradiated light. A method for estimating a feature amount of a particle size distribution, characterized in that arithmetic processing is performed using time-series data. 3. In the production of particles including a step of growing particles in a liquid, the liquid containing the particles is irradiated with light, and at least one of a scattered light amount, a transmitted light amount, and an absorbed light amount with respect to the irradiated light. A method for producing particles, comprising an operation of performing arithmetic processing using data and process data of an apparatus for growing particles. 4. In the production of particles including a step of growing particles in a liquid, the liquid containing the particles is irradiated with light, and at least one of a scattered light amount, a transmitted light amount, and an absorbed light amount with respect to the irradiated light. A method for producing particles, comprising an operation of performing arithmetic processing using time-series data. 5. An apparatus which can be used for producing particles including a step of growing particles in a liquid, the method comprising irradiating a liquid containing particles with light;
A device capable of performing arithmetic processing using one or more data of transmitted light amount and absorbed light amount and process data of a device for growing particles. 6. An apparatus that can be used for producing particles including a step of growing particles in a liquid, wherein the liquid containing the particles is irradiated with light, and the amount of scattered light with respect to the irradiated light;
An apparatus capable of performing arithmetic processing using one or more time-series data of a transmitted light amount and an absorbed light amount. 7. An apparatus that can be used for producing particles including a step of growing particles in a liquid, comprising: (i) irradiating the liquid containing the particles with light; Means for obtaining one or more of the transmitted light amount and the absorbed light amount, and (ii) arithmetic processing using one or more time-series data of the scattered light amount, the transmitted light amount and the absorbed light amount Device having various means. 8. An apparatus that can be used for producing particles including a step of growing particles in a liquid, comprising: (i) irradiating the liquid containing the particles with light; (Ii) means for obtaining one or more of the transmitted light amount and the absorbed light amount, (ii) means for obtaining process data of an apparatus for growing particles, and (ii)
i) A device having means capable of performing arithmetic processing using one or more of the scattered light amount, transmitted light amount and absorbed light amount and the process data.