JPH10211445A - Property controlling method for powder particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out control of a target property of a granular material at real time by carrying out on-line measurement of the particle size distribution of the granular material and converting the measured value into a numeric value correlating to the target property in a granular material processing process comprising at least a pulverizing process. SOLUTION: A slurry of terephthalic acid particle crystallized in a crystallization tank 1 is normally sent to a wet pulverization process 4 through a storage tank 2 and a ball valve 3 and then after the particle size distribution is measured by a particle size distribution measurement apparatus 8, the slurry is sent to a dry process 10 through a ball valve 9. In this case, the measured value of the particle size distribution measured by on-line measurement by the particle size distribution measurement apparatus 8 is sent to a computing circuit 7 to be converted into a filling ratio ϕmax and the difference in the value of the filling ratio ϕmax and the value of the set filling ratio ϕ'max is computed and then the adjustment degrees of pulverization condition factors are computed and the results are sent to an operation board 5. The adjustment degrees of such as rotation speed, pressure, gap, pulverization time, etc., which are the pulverization conditions, of a pulverizing apparatus are sent out of the operation board 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the properties of powders and granules, and more particularly, to measuring the particle size distribution of powders online at least in a process of processing the powders including a pulverizing step, For example, the present invention relates to a method for controlling the grinding conditions based on a numerical value correlated with the stirring torque value of the ethylene glycol slurry containing terephthalic acid particles.

[0002]

2. Description of the Related Art Conventionally, there have been known a number of processing steps for a granular material including at least a pulverizing step. For example, a treatment step including a wet pulverization step of terephthalic acid particles can be mentioned.

[0003] The properties of the granular material, for example, when the granular material is terephthalic acid particles, the stirring torque and the like when a terephthalic acid particle-containing ethylene glycol slurry is used as a raw material for polyethylene terephthalate are determined by the properties of the granular material. Depends on particle size distribution.

Conventionally, the control of the properties of the above-mentioned powdery granules is performed by
If the target property of the powder and granules discharged from the processing of the powder and granules is, for example, the stirring torque of the ethylene glycol slurry containing terephthalic acid particles, the ground terephthalic acid particles are sampled and the ethylene glycol slurry is sampled. Is prepared, and the particle size distribution of the granular material is controlled after the stirring torque value is actually measured.

[0005]

However, in the case of the above-mentioned method (the direct method), the measurement of the stirring torque value is performed off-line, so that it takes time, and it is necessary to avoid the generation of off-spec products due to a delay in confirmation. Can not do. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for controlling the properties of a granular material capable of controlling the desired properties of the granular material in real time.

[0006]

That is, the gist of the present invention is to measure the particle size distribution of a granular material on-line at least in a processing step of the granular material including a pulverizing step, and to obtain an object from the measured value of the particle size distribution. The present invention is directed to a method for controlling the properties of powder and granules, characterized in that the properties are converted into numerical values correlated with the properties and the pulverizing conditions are adjusted based on the numerical values.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view of an example of the control method of the present invention, and is an explanatory view of a processing step in a case where a processing step of a granular material includes a wet pulverizing step and a drying step of terephthalic acid particles.

The above-mentioned properties of the terephthalic acid particles include, for example, a stirring torque value in preparing an ethylene glycol slurry containing terephthalic acid particles. Hereinafter, a description will be given of an example in which the desired property is the stirring torque value of the ethylene glycol slurry containing terephthalic acid particles, and the filling rate _φmax value is a value correlated to the stirring torque value.

First, the above stirring torque value and filling rate φ _max
The theoretical relationship between the value and the particle size distribution will be described. In the above description, the stirring torque value of a slurry obtained by mixing a granular material such as terephthalic acid particles with a liquid is expressed by the following equation (1) (Nagata's equation) and the following equation (2) (Krieg)
er and Dougherty's equation), it is a function of the filling rate _φmax value of the granular material. The above filling ratio φ _max value is a volume fraction in the state of the closest packing of the granular material particles.

[0010]

(1) T∝ω · η (1)

Where T is the stirring torque, ω is the stirring speed, η
Indicates a slurry viscosity, and ∝ indicates a proportional relationship.

[0012]

Η = η.・ (1-φ / φ _max ) ^-a (2)

[0013] However, a represents the [η] · φ _max, η the slurry viscosity, η. Is the viscosity of the slurry solvent, φ is the slurry concentration (volume fraction), φ _max is the filling rate of the powder,
[Η] represents the intrinsic viscosity of Einstein. In addition,
The value of [η] is 2.5 in theory, but the measured value of various particles is usually 2 to 2.5, and the value actually measured for terephthalic acid particles is applied.

[0014] Then, the above-mentioned filling rate phi _max value, the following formula (3) (equation phi _max Oyama in et al), the formula (4) (formula [nu _sp Oyama in et al.) And (5) It can be obtained by converting from the value of the particle size distribution by (Oyamauchi's formula of n (d)).

[0015]

(Equation 3)

Here, φ _max is the filling rate of the powder, f (D)
Is the particle size distribution function, D is the particle size of the powder, D _max is the maximum particle size in the particle size distribution of the powder, D _min is the minimum particle size in the particle size distribution of the powder, ν _sp is represented by the following equation (4).

[0017]

(Equation 4)

Where max [] and max {} are the maximum integral values when the start value d of the integral range is changed as a variable in the range of D _min ≤d≤D _max , E is the average particle diameter, and D is the average particle diameter.
ＥE is 0 when D <E, and D−E when D ≧ E.
And n (d) is a coordination number and is represented by the following formula (5).

[0019]

(Equation 5)

However, ε (D) is a porosity in the case of a single particle size, and an approximate value (0.33) may be used instead of an actually measured value.

As described above, when the ethylene glycol slurry containing terephthalic acid particles is prepared, the stirring torque value is as follows:
Filling ratio φ that can be converted from the particle size distribution of terephthalic acid particles
There is a correlation with the _max value, and it can be estimated based on the filling rate φ _max value.

In FIG. 1, a slurry of terephthalic acid particles crystallized in a crystallization tank (1) (hereinafter abbreviated as terephthalic acid slurry) usually passes through a storage tank (2) and a ball valve (3). After being fed to the wet pulverizing step (4), it is pulverized in this step, and then the particle size distribution is measured by a particle size distribution measuring device (8). A certain drying process (10)
Sent to As the crystallization tank (1), the storage tank (2) and the drying step (10), known ones are used, and the storage tank (2) is usually provided with a stirring device.

If necessary, a part or all of the terephthalic acid slurry can be operated by operating a ball valve (3) using an operation panel (5) without passing through a wet pulverization step (4) to a particle size distribution measuring device (8). Can be sent directly to
If necessary, a part or all of the terephthalic acid slurry can be circulated to the storage tank (2) by operating the ball valve (9) using the operation panel (5).

The type of the pulverizing apparatus used in the wet pulverizing step (4) in the present invention is not particularly limited, and a known apparatus can be used, but the operation panel (5) is used in the wet pulverizing step (4). Provided. The operation panel (5) is provided with an arithmetic circuit (7) and a display device (6).

The arithmetic circuit (7) has a filling rate φ ′ _max value (hereinafter simply referred to as a set filling rate φ ′ _max value) corresponding to a set value of the stirring torque of the ethylene glycol slurry containing terephthalic acid particles in advance. Formula (A) for calculating the filling rate φ _max from the particle size distribution value, and the relationship between the difference between the filling rate φ _max value and the above set filling rate φ ′ _max value and the adjustment amount of each element of the grinding conditions Equation (B) has been input.

The measured value of the particle size distribution measured online by the particle size distribution measuring device (8) is input to the arithmetic circuit (7), and is converted into a filling rate φ _max value by the formula (A). The arithmetic circuit (7) compares the above-mentioned filling rate φ _max value with the set filling rate φ ′ _max value to calculate the difference, and then calculates the adjustment amount of the element of the pulverizing condition based on the relational expression (B). Calculate and output to the operation panel (5). And the operation panel (5)
Outputs the crushing conditions based on the adjustment amount of the crushing conditions.
That is, the rotation speed of the crusher in the wet crushing step (4),
Outputs adjustment factors and adjustment amounts such as pressure, gap, and grinding time (circulation grinding time).

The operation panel (5) has a function of issuing a signal for controlling the opening and closing of the ball valve (3) and the ball valve (9). The display device (6) can display the filling rate φ _max value, the set filling rate φ ′ _max value, their difference, and the adjustment amount of the element of the crushing condition (B).

As the particle size distribution measuring device (8),
Although not particularly limited, for example, an in-line type fluid / droplet monitoring system (“LASENTEC M200”: US LASENT), which is one of laser particle size distribution meters
EC company product name). The tip of the probe of the above-mentioned in-line type fluid / droplet monitoring system is arranged so as to directly face the flow of terephthalic acid particles in the pipe through which the crushed terephthalic acid slurry passes for on-line measurement.

The above-described in-line type fluid / droplet monitoring system irradiates laser light to terephthalic acid particles in a flow of terephthalic acid slurry, and scans the laser light based on the duration of the laser light reflected by the particles. The linear distance on the surface of the terephthalic acid particles is calculated, and this is counted as a code length and totaled. Such counting is performed for several thousand particles per second, and is sequentially output as a code length distribution in real time. The above code length distribution is not necessarily the particle size distribution itself,
Since it has a correlation with the particle size distribution, it can be used for controlling the particle size distribution.

As the ball valve (3), a known one can be used. This ball valve (3)
The terephthalic acid slurry supplied from the storage tank (2) is supplied to the wet pulverizing step (4) or bypasses the wet pulverizing step (4) and directly passes through the particle size distribution measuring device (8) to the ball valve (9). ) Is used to switch between sending to the customer or changing the distribution ratio. The switching may be performed manually, but is preferably performed by a signal of the arithmetic circuit (7) of the operation panel (5) in the wet grinding step (4).

As the ball valve (9), a known one can be used. This ball valve (9)
Circulating the terephthalic acid slurry ground in the wet grinding step (4) or the terephthalic acid slurry directly fed without passing through the wet grinding step (4) to the storage tank (2);
Alternatively, it is used to switch between feeding to the drying step (10) or changing the distribution ratio. Switching can be performed by a signal of the arithmetic circuit (7) of the operation panel (5) of the wet grinding step (4).

As a specific operation method of the process shown in FIG. 1, for example, the following cases (a) to (c) can be mentioned.

(A) This is a typical case in the present invention, in which the wet pulverizing step (4) is operated continuously after the production of the terephthalic acid slurry. This is a case in which a terephthalic acid slurry having a set stirring torque value is obtained.

In the above case, first, the particle size distribution after pulverization is measured on-line and converted into a filling rate φ _max value, and the obtained value is compared with the set filling rate φ ′ _max value, and the wet pulverization process ( The setting conditions of the pulverizing device in 4) are adjusted so that the filling rate _φmax value after pulverization matches the set filling rate _φ′max value. Thereafter, the operation shifts to the steady operation.

The terephthalic acid slurry out of the control range generated during the adjustment period of the above-mentioned pulverization conditions is adjusted by adjusting the ball valve (9) to transfer all or a part of the terephthalic acid slurry to the storage tank (2). Can be circulated.

After shifting to the steady operation, the pulverized terephthalic acid slurry is usually fed to a drying step (10) through a ball valve (9). At this time, the online particle size distribution measurement is not necessarily required to be continued when the variation over time of the particle size distribution of the terephthalic acid slurry is sufficiently small, but is preferably continuously performed for monitoring purposes.

In the above continuous measurement, when a terephthalic acid slurry having a filling factor φ _max value outside the control range is generated, the terephthalic acid slurry outside the control range is removed in the same manner as in the adjustment period of the pulverization conditions. By operating the ball valve (9), the water can be circulated to the storage tank (2).

(B) When the wet grinding step (4) is operated independently of the production of the terephthalic acid slurry, the raw terephthalic acid slurry contained in the storage tank (2) and having a uniform particle size distribution as a whole Is crushed while extracting at a constant speed to obtain terephthalic acid slurries having different stirring torque set values. In this case, the control method in (a) can be applied.

(C) When the desired stirring torque value cannot be obtained by one grinding step (4), the raw material terephthalic acid slurry is temporarily stored in the storage tank, and the storage tank is constantly stirred to obtain the terephthalic acid slurry. While maintaining the uniformity, the raw material terephthalic acid slurry is circulated and pulverized from the storage tank to the wet pulverizer (4) at a constant flow rate, and the ground terephthalic acid slurry is circulated to the storage tank.

In the above case, the pulverization conditions are appropriately set, the particle size distribution is continuously measured immediately after the wet pulverization step (4), and the pulverization is performed while converting the measured value into a filling rate φ _max value. The filling rate φ _max value to be set is compared with the set filling rate φ ′ _max value. If the values match, the ball valve (9) is operated to feed the next drying step (10) or another storage tank.

Although the above description has been made using a terephthalic acid slurry as the target powder, the present invention provides, for example,
The present invention can also be applied to granular coke used as a fluid fuel by being mixed with heavy oil or the like, or to other powders.

[0042]

According to the present invention described above, there is provided a method for controlling the properties of powders and granules capable of controlling properties such as a stirring torque value when the powders and granules are made into slurry in real time. Therefore, the industrial value of the present invention is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a processing step in a case where a processing step of a granular material includes a wet pulverization step and a drying step of terephthalic acid particles.

[Description of Signs] 1: Crystallization tank 2: Storage tank 3: Ball valve 4: Wet pulverizer 5: Operation panel 6: Display device 7: Operation circuit 8: Particle size distribution measurement device 9: Ball valve 10: Drying process

Claims (6)

[Claims] In a process for treating a granular material including at least a pulverizing step, the particle size distribution of the granular material is measured online, and the measured value of the particle size distribution is converted into a numerical value correlated with a target property. A method for controlling the properties of powders and granules, comprising adjusting pulverization conditions based on numerical values. 2. The method according to claim 1, wherein the pulverizing step is a wet pulverizing step of terephthalic acid particles. 3. The method according to claim 2, wherein the particle size distribution of the terephthalic acid particles discharged from the wet grinding step is measured. 4. The method according to claim 2, wherein the desired property is a stirring torque of the ethylene glycol slurry containing terephthalic acid particles. 5. The method for controlling the properties of a granular material according to claim 2, wherein the numerical value correlating with the desired property is the filling rate of the granular material. 6. The method according to claim 1, wherein the particle size distribution is measured by a laser particle size distribution meter.