JP3307562B2 - Crystal growth control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The present invention provides excellent crystal quality,
The present invention relates to a crystal growth control method capable of growing crystals at a high rate.

[0002]

2. Description of the Related Art In a crystal can, a crystal is formed in which a solution is supersaturated and a phase transition is made to a solid phase, and any one of a pressure state and a vacuum state is appropriately selected depending on the physical properties of the solution. For example, FIG. 1 shows a crystal can 1 having a vacuum device 12 and having a calandria inside for heating and evaporating a solution therein.
First, the inside of the crystal can 1 is evacuated by the vacuum device 12 and air 13
Is adjusted to a predetermined value through the control valve 14, and then the unsaturated solution 3
Is supplied to the crystallization liquid level 7 through the control valve 4. Subsequently, the heating steam 5 is supplied to the calandria 2 through the control valve 6 to heat and evaporate the solution to make it supersaturated. In this case, the crystallization liquid level 7 is maintained by supplying the unsaturated solution 3. After this series of operations, a crystal nucleus is generated from the seed crystal vessel 8 through the control valve 9 at the time of the crystallization concentration. Then, the solution 3 and the solvent 1
The process is completed at a liquid level at which a desired crystal (size) is supplied while supplying 0 (11 is a solvent control valve). In such growing crystals, the purity of the solution, the proportion and concentration of impurities fluctuate, and the utility also changes due to variations in raw materials, purification steps, and other devices. That is, these disturbances significantly lower the productivity by lowering the crystal growth rate, and further, new nuclei (crystal nuclei) are generated to lower the quality (grain size and the like).

In general, the crystallization phenomenon is one of the phenomena that is difficult to understand scientifically, and the crystal growth rate, which expresses the conditions of the supersaturated solution (temperature, concentration, supersaturation, etc.) as parameters, can be shown under a certain condition. Although possible, there are various problems such as supersaturation of the solution and handling of the solubility, and the phenomenon has not been sufficiently elucidated. For example, it has been known that the value of the solubility differs between the case where the measurement is performed from the unsaturated side and the case where the measurement is performed from the supersaturation side, and also differs depending on the heating state. Therefore, the present inventor has paid attention to the fact that the complexity of the crystallization phenomenon and the difference in the crystal growth rate under various conditions depend on the behavior of the spores, and have already been published in many documents or in Japanese Patent Application Laid-Open No. 61-15700. JP-B-63-65317), JP-A-1-297000, JP-B-5-422
In publication 79, etc., the concept of spores (= solute molecule association), which is a substance that has both liquid and solid properties and is different from liquids and solids, is introduced and a proposal for a crystallization control method is published. .

The intermittent crystallization system in which a solvent or a solution is intermittently supplied to a supersaturated solution (suspension) is based on the spore germination (number) And the size is increased, and a solvent or a solution is supplied on the assumption of a limit point at which a phase transition from spores to a crystal nucleus occurs. By this method, the continuous crystallization method
Significantly improved crystal productivity and quality. In other words, the crystal growth rate is higher than in the continuous crystallization method, and a very excellent effect is obtained in that the set value can be adjusted to suppress the formation of new crystal nuclei. FIG. 2A shows a solvent crystallization method in the conventional intermittent crystallization method, and FIG. 2B shows a solution crystallization method. The symbols in FIG. 2A are as follows. R ₁ , R ₂ , R ₃ : Set value (hardness) Δr ₁ : Set rise value (hardness) V ₁ : Solvent valve opening degree t ₁ : Solvent valve opening time However, R ₂ = R ₁ + Δr ₁ R ₃ = R ₂ + Δr _{1 When the} hardness value reaches the set value R ₁ , the solvent valve opens V ₁ ,
After t _1, it becomes the solvent valve is closed, at the same time hardness setting [Delta] r ₁
It increased the R _2. Then hardness value has reached the R _2, opens the solvent valve, the same operation is repeated. The symbols in FIG. 2B are as follows. R ₁ , R ₂ , R ₃ : Set value (hardness) Δr ₁ : Set rise value (hardness) where R ₂ = R ₁ + Δr ₁ R ₃ = R ₂ + Δr ₁ L ₁ , L ₂ , L ₃ : Set value (liquid level) ΔL ₁ : Set rise value (liquid level) V ₁ : Solution valve opening When the hardness value reaches the set value R ₁ , the solution valve opens V ₁ ,
When the liquid level set value is reached, the solution valve is closed, and at the same time, the hardness set value increases by Δr ₁ to R ₂ and the liquid level set value increases by ΔL ₁ . Then hardness value has reached the R _2, open solution valve, the same operation is repeated.

[0005]

However, the conventional intermittent crystallization method is an open-loop control method in view of the growth and collapse behavior of the amount of spores even when controlling the lower limit of hardness. It was not possible to cope with the cause of the slow growth rate of GaN, and it was difficult to grow the crystal at a high growth rate. The cause is roughly divided into the following three elements. Influence of raw materials and their processing steps The raw materials that make up the solution are mainly agricultural products, and the quality varies under various conditions, such as harvest time, weather, and post-harvest transfer processing. The raw material is processed by pressing, purifying, concentrating, or purifying and homogenizing the raw material by reaction, fermentation, or the like. However, changes in the solution purity and the proportion of impurities affect the crystal growth. On the other hand, in the factory design, the solution concentration is not suitable for crystal growth. As a result, the crystal growth fluctuates in the direction in which the speed decreases. Effects of Factory Utility and Supply of Solvents and Solutions The supply of utilities and solvents and solutions changes the crystal growth state when viewed from the crystal growth conditions even if the physical conditions are fixed. Influence of piping and crystal can structure It is common experience that the crystal growth state is different even if the crystal is grown using the same solution in the crystal can of the same structure, and the quality of the crystal is different. These effects make crystal growth more difficult due to changes in the types of crystals and physical properties that occur during the crystallization process. In addition, about 20 crystal growth factors also fluctuate due to these physical property changes. Among them, the flow state, which is the life of crystal growth, changes, and the other is that the thermal efficiency fluctuates, affecting crystal growth. Under such circumstances, the conventional intermittent crystal growth system described above requires a crystal growth operation target (amount of spores) to be determined by scientific knowledge (temperature, concentration, viscosity, supersaturation, hardness, conductivity, dielectric constant, etc.). It was difficult to see the results on the above, and it was difficult even for a specialist who operates a crystal to construct a program suitable for the type of crystal. In addition, since the crystal growth for maintaining a high crystal growth rate is performed by open loop control, it cannot cope with the influence of the crystal growth rate being alienated. Further, among various fluctuations, disturbances in which the crystal growth rate decreases with the passage of time are the raw materials and the refining process. There is no corresponding function.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above, and the amount of change in concentration (liquid phase), suspension density (solid phase), and spore phase in each state is generally considered. Using a biphasic sensor to detect, supply or change a certain amount of solvent, solution, pressure, etc. to create an intermittent growing state in which the value detected by the biphasic sensor drops, detect the change amount of sprouts, and detect the amount of a positive value when胞芽amount is less than the reference value, making the machining operation expression to be a negative value when large, and this value,
A special closed-loop control, in which the amount of spores that normally occur and the amount of increase in the suspension density that occurs over time are added to the set value of the intermittent crystallization method and the next set value is used as one pattern, The present invention relates to a crystal growth control method in which a crystal growth program is constituted by repeating a plurality of steps as a step, an amount of sprouts is evaluated by a plurality of patterns in the step, and an initial value is set.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a crystal can used in the present invention is:
An apparatus for generating crystals, wherein a solute in a liquid phase is incorporated into a solid phase (crystal) when a supersaturated solution is formed, and a phase transition is performed in a crystal can. Therefore, the crystal can
This is a device that supersaturates the concentration of a solute in a liquid phase (solution).
There are the following two methods for supersaturation. The method of heating the solution to evaporate the solvent to make it more soluble than the method of lowering the solution temperature to lower the solubility From these, the crystal can for making crystals may be a simple vessel, It may be provided.
Conventionally, these crystal cans have various structures, ranging in size from a few liters to 100 m ³ . Although these are variously devised depending on the type of crystal and the industry, they can be directly used as the crystal can of the present invention.

Next, the spores which are extremely important in the present invention will be described. The present inventor has already published and explained in many documents and patent gazettes, but to put it simply, spores are aggregates of solute molecules and have both liquid and solid properties as shown below. On the other hand, it is a substance different from liquids and solids. -Looks like a solution-Of course, it looks like a solution visually, and many research publications on supersaturated solutions treat it as behavior in a solution. -Looks like a solid-When looking at supersaturated solutions or suspensions using sensors such as conductivity, dielectric constant, or hardness, the increase or decrease in spores looks the same as the increase or decrease in crystals and is indistinguishable. -Looks like it is not liquid-Make a supersaturated solution such as sucrose aqueous solution, salt aqueous solution, glucose aqueous solution, sodium glutamate aqueous solution, ammonium sulfate aqueous solution and dilute it to absorbance (measurement wavelength of 190-820 nm
(Measured in seconds). Data was collected in a serially decreasing manner. 0.7 in aqueous sucrose solution
When 5% of the solvent was added, a phenomenon was observed in which the indication decreased on the short wavelength side and increased on the long wavelength side. In other words, on the short wavelength side, the spores dissolve and the amount of spores decreases (phase transition to solution), and on the long wavelength side, the dissolved mass increases despite the decrease in the solution concentration due to dilution. Rose. Therefore, it appears that a substance having an energy level different from that of the solution (associates of solute molecules = spores) has collapsed. -Appears not to be solid-In the crystallization by intermittent liquid supply, the change in the hardness meter shows that the liquid crystal falls when the solvent or the solution is supplied, and rises when the liquid supply is stopped. However, since the supply of the solvent is about several percent and the supply of the solution is about 5%, the supersaturated state is maintained even when the solvent or the solution is supplied, and the crystal that has already been formed is not dissolved. Therefore, it can be considered that a substance (spore) having an energy level different from that of a solid has collapsed by supplying a solvent or a solution.
Further, the rise of the hardness meter when the supply of the solvent or the solution is stopped is extremely sharp, and it is hardly considered that the increase in the hardness is caused by the increase in the crystal number density. That is, the increase in the crystal number density is nothing but the growth of crystals, but since such crystal growth is not considered to be occurring in a short time, a substance (spore) having an energy level different from that of a solid is generated. Can be seen as grown. Thus, spores are those that look like liquid or not liquid and that look like solid or not solid.

Further, the multi-phase sensor used in the present invention will be described. A multi-phase sensor is a detection device that detects changes in solution concentration (liquid phase) and changes in suspension density (solid phase) as a whole, and such sensors detect the state of the solution (liquid phase) and the crystal ( Since the state of the solid phase is generally detected, the amount of spores that combines liquid spores and solid spores is also detected. That is, it can be said that a plurality of phase behaviors of the spore phase at an intermediate position between the liquid phase and the solid phase are detected.
Specifically, a hardness meter for detecting hardness, a conductivity meter for detecting conductivity, a permittivity meter for detecting dielectric constant, and the like can be exemplified as the multiphase sensor.

[0010] The hardness meter has a structure in which a wing is provided at the tip of a motor rotation shaft. When the wing rotates in a suspension solution, it receives a reaction torque τ determined by the shape of the wing, and the motor rotation speed is increased. n decreases. The sensor outputs an armature current that is inversely proportional to n. Hardness is related to concentration.
A torque corresponding to ₁ and the viscosity of liquid spores Ψ ₀ is generated. In addition, a torque is generated according to the crystal number density ρ, the size of the solid spores, and the number ρ ₀ . A hardness meter that collectively detects these forces receives a reaction torque τ on the wings, where n is the number of rotations of the motor. Here, if Ψ ₀ + ρ ₀ is Ψ ₂ ,
The following equation (1) is obtained. τ = (α ₁ Ψ ₁ + α ₂ Ψ ₂ + β ₀ ρ) n (1) where α ₁ , α ₂ , and β ₀ are coefficients relating to the size and shape of the wing. Each term in the above equation (1) is affected by external conditions such as heat evaporation and temperature change. At this time, since each term has a different energy level, it is also an amount that changes by phase transition. Therefore, the change in the amount of hardness becomes difficult to understand. In addition, the amount of spores that greatly contributes to crystal growth is also an incomprehensible amount having an essentially unknown region.

In the conventional intermittent crystallization system, the process of heating and evaporating a suspension solution to raise the hardness meter indicates the amount of spores (number and size).
In this method, a solvent or a solution is supplied by assuming a limit point at which a phase transition from spores to a nucleus is assumed. With this method, the productivity and quality of the crystal were greatly improved over the continuous crystallization method. However, it was difficult to maintain high productivity and high quality because of open loop control from the viewpoint of growth and collapse behavior of spore volume. The present invention detects spores in a manner devised to increase or decrease the amount of spores for the spores exhibiting a complex behavior and changing the limit point, and processing the amount to calculate the amount of spores as an appropriate value. To submit a control method to create a special closed loop by operating the following set values. In this way, the spore germination amount is always controlled to be an appropriate amount by maintaining a crystal growth in which crystal growth is fast, maintaining a crystal growth that does not generate new nuclei other than a seed crystal, and further controlling a crystallizer for producing crystals. In the pre-process, there are many factors that change the purity, concentration, impurities, and the like, and realize crystal growth that corrects disturbances that affect crystal growth.

In the present invention, an intermittent crystallization state in which the indication of the dual-phase sensor decreases is detected, and the amount of spore germination is detected as follows. The detection of the amount of spores is carried out in advance with the lower limit deviation set value of the biphasic sensor under certain conditions, or the elapsed time of the operation target under certain conditions as the reference value, and the value obtained by actually growing under the same conditions. Are compared to detect the change state of spores. And
A processing operation formula is created so that the detected amount is a positive value when the amount of spores is smaller than the reference value, and is negative when the amount is larger than the reference value, and this is defined as A ′. This is the next set value of the intermittent growing crystal as A + A 'since the amount of spore germ that normally occurs in the set value of the intermittent growing method and the increase A in the suspension density occurs over time. That is, in the crystal growth control method of the present invention, a change in the amount of sprouts is detected (detected) when the dual-phase sensor is lowered.
Then, the amount is processed and adjusted (adjusted), and a special closed-loop control, which sets the next set value (operation unit) of the intermittent growing crystal, is defined as one pattern. You do it.

Examples of criteria under certain conditions in the present invention are shown below. When the lower limit deviation value of the multi-phase sensor is used as a reference (FIG. 3,
5) -1) method (Figure 3 relative to the lower deviation [Delta] W _LT01 diploid sensors in a solvent valve open time t ₀₁₎ -2) liquid level rises deviation [Delta] L ₀₁ or multiple phases in a solution valve open time t ₀₁ Method based on the lower limit deviation value ΔW _LL01 of the sensor (FIG. 5) In the case of using the opening time of the operating valve or the deviation of the solution valve rise as a reference (FIGS. 4 and 6) -1) The solvent in the lower limit deviation value ΔW _L01 of the multi-phase sensor how relative to the valve opening time t ₀₁ (FIG. 4) -2) a method for the reference solution valve increases the deviation [Delta] L _W01 or solution valve open time t ₀₁ in the dual-phase sensor lower deviation [Delta] W _L01 (FIG. 6)

The method for detecting the amount of change in spores according to the present invention is as follows.
Shown below. When the lower limit deviation value of the multi-phase sensor is used as a reference (FIG. 3,
Figure 5) -1) Lower limit deviation value ΔW of the multi-phase sensor_Lt01Based on
And the value ΔW measured under the same conditions_L1XRatio ΔW to_Lt01÷
ΔW_L1X2) Lower limit deviation value ΔW of multi-phase sensor_LL01Based on
And the value ΔW measured under the same conditions_LL1XRatio ΔW to_LL01÷
ΔW_LL1X(Fig. 5) When operating valve opening time or solution valve rise deviation is used as a reference
(FIGS. 4 and 6) -1) Solvent valve opening time t₀₁Measurement under the same conditions
Set value t_1XAnd the ratio t _1X÷ t₀₁-2) Solution valve rise deviation ΔL_W01With the same conditions
The value ΔL measured below_{L1 X}Ratio ΔL_L1X÷ ΔL_W01Take
(Fig. 6) or solution valve opening time t₀₁Measured under the same conditions based on
Value Δt_1XRatio Δt to_1X÷ t₀₁How to take (Figure 6)

The method of processing and calculating the change amount of spore sprouts in each of the above-mentioned standards and setting it as a set value will be described below. When the lower limit deviation value of the multi-phase sensor is used as a reference (FIG. 3,
Fig. 5) -1) The change in the amount of _spores is detected by ΔW _Lt01 ÷ ΔW _L1X ,
[(ΔW _Lt01 ÷ ΔW _L1X ) × _BC ] ÷ D = A ′, processed into positive and negative values, and added to the increase A of the suspension density A +
Method of setting A ′ to the next set value W _1X1 (FIG. 3) -2) Detecting a change in the amount of spores by ΔW _LL01 ÷ ΔW _LL1X ,
[(ΔW _LL01 ÷ ΔW _LL1X ) × B−C] _方法 D = A ′, processed into positive and negative values, and the increase in suspension density A + A ′ is set to the next set value W _1X1 (FIG. 5). When the opening time or solution valve rise deviation is used as a reference (FIGS. 4 and 6) -1) A change in the amount of spores is detected at t _1X ÷ t ₀₁ , and [(t _1X
{T ₀₁ ) × BC] ÷ D = A ′, processed into positive and negative values, and the value A + A ′ obtained by adding the increase A of the suspension density to the next set value W
How to _1X1 changes in (4) -2)胞芽amount detected by ΔL _L1X ÷ ΔL _W01,
[(ΔL _L1X ÷ ΔL _W01 ) × _BC ] ÷ D = A ', processed into positive and negative values, and added to the increase A of the suspension density A +
The A 'is detected by the method (FIG. 6) or t _1X ÷ t ₀₁ to the next set point W _{1X1, [(t 1X ÷ t 01) ×} B-
C] A method of processing to a positive or negative value with ÷ D = A 'and adding the value A + A' obtained by adding the increase amount A of the suspension density to the next set value W _1X1 (FIG. 6)

These control methods will be described with reference to FIGS. 1. Solvent crystallization method (fixed solvent valve opening time) Fig. 3: Comparison between the lower limit deviation value of the multi-phase sensor and the measured value of the lower limit deviation of the multi-phase sensor grown under the same conditions. 2 shows a pattern constituting one step of the present invention, and shows a crystallization record and set values of a multiphase sensor. FIG. 3B shows an operation diagram of the solvent valve. FIGS. 3 (a) of Symbol Description a ₁ ~a _6: recording the legend W diploid sensor: dual phase sensor value, delta W _1X1: dual-phase sensor configuration of the operation result rise value W _1-1: the first time step Set value of the first multi-phase sensor (a ₂ is the point where the measured value matches W _1-1 ) _1-1 : Setting of the first pattern of the first step W _1-2 : Second multi-phase of the first step Sensor set value (a ₆ is the point where W _1-2 matches the measured value) _1-2 : Setting of the second pattern of the first step ΔW _Lt01 : Setting of the multi-phase sensor when the solvent valve opening time is constant (t ₀₁ ) Lower limit deviation reference value (a ₃ ) _Lt : Lower limit of multi-phase sensor with fixed solvent valve open time ₀₁ : Lower limit deviation of the first step ΔW _L1X : Measured value of lower limit of multi-phase sensor reaching fixed solvent valve open time (t ₀₁ ) (a _{4) L1:} a lower limit deviations first time step _X: Legend measurements Figure 3 (b) V _1: soluble Valve opening t _01: solvent valve opening time reference set value (a _3, a ₄ are t ₀₁
T ₁ : Solvent valve open time setting (a ₅ is the point at which t ₁ time has elapsed)

Operational Description of FIG. 3 The multi-phase sensor value W in a ₁ is heated and evaporated and rises.
It reaches the set value W _1-1 (a _2). As a solvent valve V ₁ open at _two points, W value is lowered (a _3). The multi-phase sensor value ΔW _L1X at the point a ₄ after the lapse of the time t ₀₁ is stored, and when the _temperature reaches the point a ₅ after the lapse of the time t ₁ , the solvent valve is closed, and the multi-phase sensor value is the same as the point a _1. next, the solvent valve is opened again in a _6-point has been reached following settings W _1-2. The stored W _L1X takes a ratio with a predetermined reference value ΔW _Lt01 , performs the calculation of the following equation, and sets the next set value to W 3 of the following equation.
_1-2 . ΔW _1X1 = A + [(ΔW _Lt01 ÷ ΔW _L1X ) × B−C] ÷ D (1) A ′ = [(ΔW _Lt01 ÷ ΔW _L1X ) × B−C] ÷ D (2) W _1-2 = W _{1 -1} + ΔW _1X1 (3) However, A. B. C. D is a set constant deviation value relating to crystals of different varieties and types of crystals (size, purity, etc.). The two equations include correction values due to various disturbances and positive and negative values. Equation 3 is the second set value of the multi-phase sensor. This control loop is composed of a ₂ , a ₃ , a ₄ , a ₅ , and a _6, which is defined as one pattern (special closed loop), and the control defining the number of repetitions is defined as one step.

2. Solvent crystallization method (determination of the lower limit deviation value of the multi-phase sensor) Fig. 4: Set value of the lower limit deviation of the multi-phase sensor, its elapsed time reference, and comparison of the elapsed time under the same conditions Fig. 4 (a) shows one of the crystallization programs. Fig. 4 shows patterns constituting steps, and shows crystallization records and set values of a multi-phase sensor. FIG. 4B shows the operation diagram of the solvent valve. FIGS. 4 (a) of Symbol Description a ₁ ~a _6: recording the legend W diploid sensor: dual phase sensor value, delta W _1X1: dual-phase sensor configuration of the operation result rise value W _1-1: the first time step Set value of the first multi-phase sensor (a ₂ is the point where the measured value matches W _1-1 ) _1-1 : Setting of the first pattern of the first step W _1-2 : Second multi-phase of the first step Sensor setting value (a ₆ is the point where W _1-2 matches the measured value) _1-2 : Setting of the second pattern of the first step ΔW _L01 : Lower limit deviation reference setting value of the first step (a ₃
And a ₄ ) _L : Lower limit setting of multi-phase sensor ₀₁ : First step reference ΔW _L1 : Lower limit deviation setting value of solvent valve closing at first step (a ₅ ) _L1 : Lower limit setting of first step Figure 4 (b) Symbol Description V ₁ : Solvent valve opening degree t ₀₁ : Solvent valve opening time reference (a ₃ ) t _1X : Solvent valve opening time reaching the set value of lower limit deviation of multi-phase sensor (a ₄ )

Operational Description of FIG. 4 The multi-phase sensor value W in a ₁ is heated and evaporated and rises.
It reaches the set value W _1-1 (a _2). As a solvent valve V ₁ open at _two points, W value is lowered (a _3). The time t _1X value of the point a ₄ when the multi-phase sensor lower limit deviation set value W _L01 is reached is stored, and when the multi-phase sensor lower limit deviation set value a ₅ is reached, the solvent valve is closed and the multi-phase sensor is closed. the value becomes the same state as ₁ point a, the solvent valve is opened again in a _6-point has been reached following settings W _1-2. The stored t _1X takes a ratio with a predetermined reference value t _01, and the following equation is calculated, and the next set value is W _{1-2 of the} following three equations. ΔW _1X1 = A + [(t _1X ÷ t ₀₁ ) × B−C] ÷ D (1) A ′ = [(t _1X ÷ t ₀₁ ) × B−C] ÷ D (2) W _1-2 = W _{1 -1} + ΔW _1X1 (3) However, A. B. C. D is a set constant deviation value relating to crystals of different varieties and types of crystals (size, purity, etc.). The two equations include correction values due to various disturbances and positive and negative values. Equation 3 is the second set value of the multi-phase sensor. This control loop is composed of a ₂ , a ₃ , a ₄ , a ₅ , and a _6, which is defined as one pattern (special closed loop), and the control defining the number of repetitions is defined as one step.

3. Solution crystallization method (constant liquid level rise deviation) Fig. 5: Comparison of measured values of the lower limit deviation of the crystallization multiphase sensor under the same conditions based on the lower limit deviation value of the multiphase sensor Fig. 5 (a) shows one of the crystallization programs. Fig. 4 shows patterns constituting steps, and shows crystallization records and set values of a multi-phase sensor. FIG. 5B shows the recording of the liquid level and the set values. FIG. 5C shows an operation diagram of the solvent valve. Symbol Description a ₁ ~a in FIG 5 (a) _6: dual-phase sensor of the recording Description Symbol W: diploid sensor value delta W _1X1: calculation result of the multi-phase sensor settings increase value W _1-1: one first time step times th multi-phase sensor setting value (a ₂ points were consistent with the measured values and W _{1-1) 1-1:} Configuration of the first-time pattern of the first time step W _1-2: second time dual-phase sensor first time step setting (a ₆ point were consistent with the measured values and W _{1-2) 1-2:} first time set ΔW a second time pattern of step _LL01: diploid sensor set lower in the liquid level rises deviation constant ([Delta] L ₀₁₎ Deviation reference value (a ₃ ) _LL : Lower limit of liquid level reference ₀₁ : Reference of first step ΔW _LL1X : Measurement value of lower limit deviation of multi-phase sensor (a ₄ ) _{1X which} has reached a constant liquid level rise deviation (ΔL ₀₁ ) Measurement of the first step Symbol explanation of FIG. 5B _L1-1 : First liquid level setting value of first step ( a ₂ ) L _1-2 : Second liquid level set value of first step (a ₅ ) ΔL ₀₁ : Liquid level rise reference value of first step (a ₃ , a
₄ ) ΔL ₁ : Set value of liquid level rise at the first step Symbol explanation of Fig. 5 (c) V ₁ : Solution valve opening

Operational Description of FIG. 5 The multi-phase sensor value W in a ₁ is increased by heating and evaporating,
It reaches the set value W _1-1 (a _2). As a solution valve V ₁ open at _two points, W value is lowered (a _3). The multi-phase sensor value ΔW _LL1X at the point a ₄ when the liquid level rise deviation set value ΔL ₀₁ has been reached is stored. When the liquid level falls further, the solvent valve is closed when the liquid level lower deviation set value a ₅ has been reached. sensor value becomes the same state as ₁ point a, solution valve is opened again in a _6-point has been reached following settings W _1-2. The stored W _LL1X takes a ratio with a predetermined reference value ΔW _LL01 , performs an operation of the following equation, and the next set value is W _{1-2 of the} following equation 3. ΔW _1X1 = A + [(ΔW _LL01 ÷ ΔW _LL1X ) × B−C] （D (1) A ′ = [(ΔW _{LL01 ＢΔW LL1X} ) × B−C] ÷ D (2) W _1-2 = W _{1 -1} + ΔW _1X1 (3) L _1-2 = L _1-1 + ΔL ₁ (4) B. C. D is a constant relating to crystals of different varieties and types of crystals (size, purity, etc.). The two equations include correction values due to various disturbances and positive and negative values. Equation 3 is the second set value of the multi-phase sensor. Equation 4 is the second set value of the liquid level. This control loop is composed of a ₂ , a ₃ , a ₄ , a ₅ , and a _6, which is defined as one pattern (special closed loop), and the control defining the number of repetitions is defined as one step.

4. Solution crystallization method (multiphase sensor lower limit deviation)
Fig. 6: Crystal growth multi-phase sensor under the same conditions with the liquid level rise deviation standard
Figure 6 (a) shows one step in the crystallization program.
Shows the constituent patterns, and records and sets up
Indicates a fixed value. FIG. 6B shows the recording of the liquid level and the set values.
You. FIG. 6C shows an operation diagram of the solution valve. Explanation of symbols in FIG.₁~ A₆: Symbol for recording of multi-phase sensor W: Multi-phase sensor value Δ W_1X1: Multi-phase sensor setting rise value W of calculation result_1-1: Setting of the first multi-phase sensor for the first step
Value (a_TwoIs W_1-1And the point that agrees with the measured value) W_1-2: Setting of the second multi-phase sensor in the first step
Value (a₆Is W_1-2ΔW)_L01: Lower limit deviation reference set value of the first step (a
_ThreeAnd a_Four)_L : Multi-phase sensor lower limit setting₀₁ : First step reference ΔW_L1: Under the multi-phase sensor with the solution valve closed in the first step
Limit deviation set value (a_Five) _L1 : Lower limit setting of the first step Symbols in FIG. 6B L_1-1： First liquid level setting value of the first step L_1-2: Second pattern liquid level set value of first step ΔL₁： Liquid level setting rise value ΔL of the first step_W01: Constant of the lower limit deviation of the multi-phase sensor in the first step
Liquid level rise deviation standard_W01 : Lower limit of the multi-phase sensor for the first step ΔL_L1X: Constant of the lower limit deviation of the composite sensor in the first step
Liquid level rise measurement_L1X : Lower limit of multi-phase sensor in first step, above liquid level
Ascending measurement Explanation of symbols in Fig. 6 (c) V₁： Solution valve opening

Operational Description of FIG. 6 The multi-phase sensor value W in a ₁ is heated and evaporated and rises.
It reaches the set value W _1-1 (a _2). As a solution valve V ₁ open at _two points, W value is lowered (a _3). The liquid level rise ΔL at a point ₄ when the multi-phase sensor lower limit deviation set value ΔW _L01 is reached
_{The L1X} value is memorized and further lowered, when the multi-phase sensor lower limit deviation set value ΔW _L1 a reaches ₅ points, the solution valve is closed, the multi-phase sensor value becomes the same state as the a ₁ point, and the next set value W
The solution valve is opened again in a _6-point was reached _1-2. The stored ΔL _L1X takes a ratio with a predetermined reference value ΔL _W01 , performs the operation of the following equation, and the next set value is W _{1-2 of the} following equation. ΔW _1X1 = A + [(ΔL _L1X ÷ ΔL _W01 ) × B−C] _１D (1) A ′ = [(ΔL _L1X ÷ ΔL _W01 ) × B−C] ÷ D (2) W _1-2 = W _{1 -1} + ΔW _1X1 (3) However, A. B. C. D is a constant relating to crystals of different varieties and types of crystals (size, purity, etc.). The two equations include correction values due to various disturbances and positive and negative values. Equation 3 is the second set value of the multi-phase sensor. This control loop comprises a ₂ , a ₃ , a ₄ , a ₅ ,
composed of a _6, which was one of the patterns (special closed loop), the control that defines the number of repeats and one step.

An operation method for setting the initial value will be described.
The initial value setting of the multi-phase sensor is switched to manual or automatic during the crystallization program. The manual initial value setting includes a method of setting a numerical value or a method of providing at least three setting values in advance and selecting one of them. The initial value setting to be automatically performed is as follows: Equation A ′ = ((ΔW _Lt01 ÷ ΔW _L1X ) in _FIGS .
× BC] ÷ A method of automatically selecting from the positive / negative information of D and the increase / decrease information compared with the immediately preceding operation, the initial value immediately after the crystallization operation among a plurality of initial values is the same as the initial value of the same old growing crystal Subsequent repeated solvent (or solution)
There is a method of automatically selecting an initial value from the positive / negative information of the calculation result obtained in the growth and the increase / decrease information compared with the immediately preceding operation.

A method of constructing a crystal growth program using the special closed loop control as one pattern and repeating a plurality of the patterns as steps will be described below. In the batch crystallization operation, the inside of the crystal can is evacuated, the solution is sucked,
By heating and evaporating, supplying a seed crystal at a crystallization concentration, and supplying a solvent (pressure) or a solution, the seed crystal is grown into a crystal of a predetermined size, thereby completing the crystal growth. FIG. 7 shows the configuration of a step pattern having two initial value settings. The crystallization program consists of steps, such as solvent crystallization and solution crystallization. Steps are composed of patterns. There is an initial value setting in these series of setting values, and the initial value setting value stores the positive / negative and magnitude of the operation result in one pattern and is determined from these results (the pattern is determined by Until you decide on the setting).

[Table 1] In each pattern, a special closed loop is used to detect the change in the amount of spores due to the changing element and control to change the next set value. In each step, the initial value set value is determined by the positive or negative of A ', one before, and the comparison magnitude. decide.

Other examples and construction of a crystal growth program
Will be described. Crystals of different varieties, and crystal size
Crystallizers for crystals of different purity and purity, or
In addition, in the crystallization of crystallizers of various structures,
And the amount of change in spores is revealed by the following method.
Next time, special closed loop control to determine the set value
Can be crystallized. When performing solvent (or solution) crystallization using a multi-phase sensor
If the reference is based on the previous crystallization operation (pattern)
Method 1) Double phase sensor obtained by previous crystallization (pattern)
Lower limit deviation measurement value ΔW_{L1 X}Or melting valve open elapsed time t_1XAnd
Liquid level rise deviation measurement value ΔL_L1X(Elapsed solution valve opening time)
The next set value is calculated by comparing with the same measured value
decide. 2) A multi-phase sensor obtained with the same different crystal growth (pattern)
-Lower limit deviation measurement value ΔW _L1XAlternatively, the solvent valve opening elapsed time t_1X
And liquid level rise deviation measurement value ΔL_L1X(Solution valve opening time)
Set the next set value by comparing and calculating with the same measured value of this time as a reference
To determine. 3) In the solution crystallization, the lower limit deviation set value Δ of the multi-phase sensor
W_L1When the solution is stopped by the liquid level setting value ΔL₁ΔL₁Until intermittent
When the solution is supplied by the crystallization method or the continuous crystallization method,
Sensor rise deviation set value W_U1(Liquid level deviation measurement value ΔL
_U1XAnd the multi-phase sensor rise deviation set value W_U01Below
It will be noted in the note. In the case of intermittent method W_U1= A '([Delta] L_U1X/ ΔL₁) + [(ΔL_1X/ Δ
L₀₁) × B′−C ′] / D ΔL₁How to repeat until reaching. Pattern in this way
Although the set value of the next multi-phase sensor is determined,
Next set value ΔW_1X1Have two arithmetic expressions when determining
One. ΔW_1X1= A + [(ΔL_1X/ ΔL₀₁) × BC] / D In the case of continuous growth ΔW_L1Is reached, the multi-phase sensor
Difference set value ΔW_U01Is first raised and the measured value is ΔW_U01To
When arrived, constant solution valve opening V_U1At ΔL₁Until it reaches
Supply by Set the multi-phase sensor setting value according to the method shown in FIG.
You. W_1-2= W_1-1+ W_1X1 W_1X1= A + [(ΔL_L1X/ ΔL_W01) × BC] / D

[0027]

As described above, according to the crystal growth control method of the present invention, the following special effects can be obtained.

(1) Crystal growth can be performed at a high rate of crystal growth.
In the conventional intermittent crystallization system, in terms of supplying a solvent and a solution,
There was a problem that the amount of spores varied, and the crystallization time was long. That is, the variation in the amount of spores is caused by the complicated behavior of the suspension solution in the crystal can, and also caused by many disturbances such as equipment and raw materials related to the crystal can. On the other hand, in the present invention, a method of correcting a state in which the crystal growth rate is inhibited by a special pattern by a special closed loop control is adopted. In addition, a method of correcting the crystal growth program with initial values is used for a large disturbance caused by a variation in the number of seed crystals generated during a raw material, a cleaning step, or crystallization.

(2) Improvement in crystal quality is realized. It is well known that the purity of a solution greatly affects the crystal growth rate and crystal purity. That is, using the same solution, a crystal growing at a high crystal growth rate can improve the quality by increasing the purity of the crystal and decreasing the color value (color value). Therefore, the crystal growth according to the present invention, which grows crystals at a high crystal growth rate without generating new crystal nuclei, improves the crystal purity and particle size distribution (bulk specific gravity), facilitates solid-liquid separation, and improves the environment of the factory. To improve.

(3) Improvement in productivity is realized. Crystal growth at a high crystallization rate improves the productivity of the crystallization process (one batch productivity can be evaluated by the difference between the purity of the feed solution and the purity of the honey after the crystal growth). In the present invention, an improvement of 20 to 30% can be maintained. In addition, when the desired crystal has a lower limit of purity, the use of a low-purity solution reduces the amount of the solution used for the recovery and growth, and the productivity is improved by reducing the number of batches for forming a certain crystal. .

(4) The target to be crystallized is not limited by making various multiphase sensors usable. Crystals of different materials and crystal types have different crystal growth rates, and also have various levels of viscosity. The crystallization operation of the solvent, pressure and solution corresponding to these can be performed.

(5) Program control can be easily performed. Since the method of automatically determining the program control is adopted, it is possible to realize the crystal growth with a high crystal growth rate, and to easily perform the crystal growth operation for the first time. Further, it is possible to easily start up the same crystal in different factories. Since the detection of the amount of spores is performed by software processing, there are various methods. By processing and storing the sign, the magnitude, and the size of the spores, a better crystal growth program can be constructed by a touch operation.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an example of a crystal can.

FIGS. 2A and 2B are graphs showing crystallization in a conventional intermittent crystallization system, wherein FIG. 2A shows a change in hardness value in solvent crystallization and FIG.

FIG. 3 is a graph showing a comparison between a reference value of a lower limit deviation value of a multi-phase sensor and a measured value of a lower limit deviation value of a multi-phase sensor grown under the same conditions when the solvent valve opening time is constant. 3 shows a pattern constituting one step of the present invention, showing the crystallization record and set values of the multi-phase sensor, and FIG.

FIG. 4 is a graph showing a lower limit deviation value of a multi-phase sensor, an elapsed time reference thereof, and an elapsed time comparison under the same condition;
(A) shows a pattern constituting one step in the crystallization program, showing crystallization records and set values of the multiphase sensor, and (b) shows a solvent valve operation diagram.

FIG. 5 is a graph showing a comparison between a measured value of a lower limit deviation of a crystallization multi-phase sensor under the same conditions and a reference value of a lower limit deviation value of a multi-phase sensor when the liquid level rise deviation is constant. 4A and 4B show patterns constituting steps, showing a crystallization record and set values of a multi-phase sensor, FIG. 5B shows a liquid level record and set values, and FIG. 5C shows a solvent valve operation diagram.

FIG. 6 is a graph showing a lower limit deviation value of a multi-phase sensor, a reference value of the liquid level rise deviation, and a comparison of values of the crystallization multi-phase sensor under the same conditions, wherein (a) shows one step in the crystallization program. The pattern to be composed is shown, the crystallization record and the set value of the multi-phase sensor are shown, and (b) shows the record of the liquid level and the set value.
(C) shows a solution valve operation diagram.

FIG. 7 is a graph showing a crystal growth program having two initial value settings.

Claims (1)

(57) [Claims] 1. A multi-phase sensor which uses a multi-phase sensor for detecting the amount of change in a liquid phase, a solid phase, and a spore phase in each state as a whole, and supplies or changes a fixed amount of a solvent, a solution, pressure, etc. There make intermittent IkuAkira state value detecting is lowered, it detects a change amount of胞芽, a negative value when the amount detected, a positive value when胞芽amount is less than the reference value, often Then, add this value, the set value of the intermittent crystallization method, the amount of spores that normally occur, and the increase in the suspension density that occurs over time , and add the value to the next set value. A crystal growth control that configures a breeding program by using a special closed loop control as one pattern, and repeating a plurality of these steps as a step, and evaluating the amount of spores in a plurality of patterns in the step to set an initial value. Method.