JPH06306002A - Centrifugal separation of bisphenol a-phenol adduct - Google Patents

Abstract

PURPOSE:To carry out a long-term stable operation by preventing vibration of a filtration tank caused by, e.g. concentration change in centrifugal separation of crystallized bisphenol A-phenol adduct from a phenol solution (slurry) of bisphenol A. CONSTITUTION:This invention relates to a method for supplying slurry to the bottom of a filtration tank and forming a cake through a cake formation zone. In this method, the formation of a cake is carried out while making a uniform cake formation zone by continuously breaking an abnormally grown cake in a cake formation zone using a cake formation control liquid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for centrifugally separating a phenol adduct of bisphenol A. More specifically, it relates to a method of centrifuging and separating a phenol adduct of bisphenol A from a phenol solution of bisphenol A stably for a long time.

[0002]

2. Description of the Related Art Bisphenol A, which corresponds to 2,2-bis (4-hydroxylphenyl) propane, is widely used as a main raw material for epoxy resins, polycarbonate resins, etc. High-purity bisphenol A is required for quality improvement. As one of the special applications, for example, in polycarbonate resins, the demand for optical materials has increased in recent years, and it is required to supply bisphenol A which is more colorless and higher in purity than ever before.

As a method for purifying bisphenol A in a process for industrially producing bisphenol A,
There is a method of utilizing the property that bisphenol A forms an adduct with phenol and crystallizes in a phenol solution. That is, when bisphenol A is produced using phenol and acetone as main raw materials, a bisphenol A phenol solution containing crystals of the phenol adduct of bisphenol A and production impurities is obtained by a crystallization operation in a slurry state.

For the solid-liquid separation, a belt filter, a tray filter, a drum filter, and a centrifugal filtration separator have been conventionally used. Of these various filtration type solid-liquid separators, in the case of suction type belt filters, tray filters and drum filters, a large amount of the adhered liquid is contained in the solid layer after the solid-liquid separation, and therefore bisphenol A is used in the subsequent step. However, it has a drawback that the amount of evaporated phenol increases when the phenol adduct is dissolved and the phenol is distilled off.

On the other hand, the centrifugal filtration separator uses a centrifugal force that is incomparable to gravity and has a filtration tank having a side wall for solid-liquid filtration separation, so that the solid-liquid separation speed is high. In addition, it is a separator that can be almost completely separated, on the other hand, can easily collect liquid components, and can be conveniently used unless the object is in a colloidal state. In fact, in order to separate the crystals of the phenol adduct of bisphenol A from the bisphenol A phenol solution (slurry) which has been subjected to the crystallization operation, the above-mentioned function of this centrifugal filtration separator is suitable and often used and applied. It has been tried.

However, when this centrifugal filtration separator is used, the problem of increased evaporation load due to the adhering liquid as in the case of the suction type described above can be avoided, but the phenomenon of abnormal vibration of the filter tank often occurs. As a result, the solid-liquid separation performance remarkably deteriorates, and the destabilization of the centrifugal filtration state accompanied by the occurrence of vibration leads to a variation in the quality of the final product, bisphenol A, which has been a problem. This problem of vibration generation will be analyzed in more detail. In order to operate the centrifugal filtration separator efficiently, it is most important to maintain the stable rotation axis of the internal filtration tank. It often deposits on the inner wall non-uniformly in the circumferential direction, that is, asymmetrically with respect to the central axis, so the supporting state of the filtration tank becomes unbalanced, which causes abnormal vibrations and a stable rotating shaft. Is likely to be unable to be maintained for a long time. As a result, abnormal contact between the main body of the centrifugal filtration separator and the rotating filtration tank, reduction in filtration efficiency, promotion of uneven deposition of the adduct on the inner wall of the tank, separation of the adduct from the inner wall of the tank, etc. It is easy to cause

The mechanism of the occurrence of a special phenomenon of non-uniform deposition in the crystal separation of the phenol adduct of bisphenol A is not clear, but the phenomenon itself does not occur when the slurry concentration is selected or during the supply thereof. The change in concentration seems to have a significant effect. For example, when a continuous process is adopted, a phenol solution having an adduct concentration of 0% is usually used at the start of operation, and a change in concentration is inevitable because an operating condition of gradually increasing the slurry concentration is adopted. Of the bisphenol A or the concentration of the bisphenol A added to the phenol solution due to the change of the crystallization operation conditions, and the slurry concentration is usually 20 from the viewpoint of the fluidity at the time of feeding and the feeding efficiency.
Approximately 40% by weight, but if it is constant within such a range, the rotation of the filtration tank is stable, and if it is much lower than 20% by weight, it is unstable even if the concentration is constant. It has been observed that when it exceeds 40% by weight, the supply state of the slurry becomes unstable and, as a result, the rotation becomes unstable. There is a plan to provide a cyclone slurry concentration step before the centrifugal filtration separation step in order to prevent the above-mentioned low concentration slurry from being supplied, but this is not preferable because it complicates the step. that's all,
The case where the above-mentioned additive starts to be non-uniformly deposited has been described. However, when the non-uniformity occurs once and the filtration tank starts to vibrate, there is a phenomenon in which the non-uniformity is further called and the vibration becomes intense.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to produce a bisphenol A solution by using a centrifugal filtration separator for a slurry consisting of a bisphenol A phenol solution and crystalline bisphenol A phenol adduct. The purpose is to prevent the vibration of the filtration tank from occurring in the solid-liquid separation process, and to eliminate it even if it occurs, but ultimately, this vibration prevents the solid-liquid separation operation from being stable for a long time. It is possible to produce higher quality bisphenol A with less variation in quality.

[0009]

Means for Solving the Problems The present inventors have conducted extensive research to solve the above problems, and as a result, bisphenol A
When a crystal consisting of the phenol adduct of is filtered and is about to be deposited as a cake on the inner wall of the in-machine filter tank from the slurry state, if the deposition of the crystal begins to occur nonuniformly in the inner circumferential direction of the filter tank, Immediately, spray the phenol solution to the non-uniform deposition portion, and find that the rotation is stable if it is poured away and is in a uniform state in the circumferential direction, that is, in a state where the cake is as symmetrical as possible with respect to the central axis. The present invention has been completed. That is, the gist of the present invention is to separate a bisphenol A phenol adduct from a slurry containing a bisphenol A phenol adduct crystallized by crystallizing the adduct as a cake through a cake generation zone by a centrifugal filter separator. In the method, at least a part of the cake formed in the cake formation zone of the inner wall surface of the filtration tank is filtered off while being filtered off with a cake flow-off liquid (cake generation control liquid). It is in a centrifugal filtration separation method.

The contents of the present invention will be described in detail below. The centrifugal filtration separator used in the present invention is generally used for its application and is not particularly limited. That is, it is a centrifugal filtration separator structurally provided with a filtration tank that rotates uniaxially at high speed inside and a body that receives and discharges the filtrate outside. When the centrifugal filtration separation is performed in a continuous process, the slurry is continuously supplied and immediately filtered and separated on the inner wall surface of the filtration tank, so that the rotating shaft is not limited to the vertical type or the horizontal type. However, the vertical type is easier to maintain the stability of rotation, and the horizontal type is easier to take out the filtered adduct.

The diameter of the filtration hole on the inner wall surface of the filtration tank is appropriately selected in consideration of factors such as the particle size distribution of the phenol adduct and the hardness of the adduct (crystal). Since the centrifugal force is applied and the surface tension of the filtrate is hardly a problem, it is preferable to provide as many fine holes as possible from the viewpoint of separation efficiency. It is sufficient for the main body to have a function of receiving and discharging the filtrate that has passed through the filtration wall, and the same one as that of a normal centrifugal filtration separator can be used.

In order to perform centrifugal filtration separation, the slurry can be supplied to the filtration surface of the inner wall of the filtration tank by various means, but the slurry is once jetted and supplied to the bottom of the filtration tank, preferably the bottom provided with the dispersion plate, The method of uniformly pushing the slurry toward the inner wall surface of the filter tank in the periphery and further moving the slurry along the inner wall surface of the filter toward the opening of the filter tank is the uniformity of the slurry supply in the circumferential direction, the rotation axis direction. Forming a uniform slurry concentration gradient (gradient of filtration concentration) in, the slurry being filtered on the inner wall surface of the filtration tank or the cake deposition layer after filtration can be moved to the opening side of the filtration tank by the slurry supply pressure. It is preferable in that the cake deposited layer after filtration is easily taken out continuously from the opening. The diameter of this dispersion plate can be selected variously, but it is convenient to bring the cake deposition layer out of the tank in a piston type manner by bringing it closer to the inner diameter of the filtration tank.

A slurry supply nozzle may be provided at the bottom of the filtration tank so that the slurry can be moved. However, in order to improve the uniformity of the slurry supply in the circumferential direction of the bottom of the filtration tank, a large number of slurry can be arranged in a circle. Good. Further, it is also possible to conveniently use a system in which a perforation is appropriately provided along the outer peripheral edge of the annular portion of the slurry supply pipe having the annular portion in the filtration container, and the slurry is jetted from the perforation.

The concentration of the phenol solution of the phenol adduct of bisphenol A used in the present invention has been determined to be suitable for the above-mentioned conventional centrifugal filtration separation technique.
0 to 40% by weight is the most preferable, but 0 to 50% by weight can be applied by using the method of the present invention. That is, according to the method of the present invention, since the non-uniform portion is constantly removed and corrected as described later, the method can be used even in a low concentration or high concentration region where vibration of the filtration tank is apt to occur. When adjusting the adduct concentration to 0 to 50% by weight (preferably 20 to 40% by weight), the higher concentration of bisphenol A is preferable, but 0 to 50% by weight.
If Further, the slurry temperature affects the viscosity of the slurry and is related to the filtration rate, but generally 20 to 80 ° C. is suitable including the handling property.

According to the method of the present invention, when the above-mentioned centrifugal filtration separator is used to deposit a phenol adduct of bisphenol A into a powder having almost no fluidity on the inner wall surface of the filtration tank, the cake is circulated in the circumferential direction. The cake-forming liquid (cake formation control liquid) is sprayed on at least a part of the cake formed in the cake-forming zone that is still in a fluid state before it is evenly formed. At the same time, it is intended to form a cake deposition layer uniformly in the circumferential direction. Observe the process of cake formation (for example, by stroboscopic photography synchronized with the rotation speed of the filter container)
However, when the centrifugal filtration separator is operating normally, the slurry moves from the uniform liquid into the filtration tank mouth side, and becomes a solid cake with a uniform shape in a short time. Since the length of the cake formation zone with an unstable shape is extremely short, even if a small amount of abnormal flow occurs in this cake formation zone and some cake is formed,
The circumferential non-uniformity of the cake formation zone does not seem to affect the destabilization of the rotation of the filter tank.

However, it has been observed that if the slurry concentration is lowered or fluctuates, the cake forming zone becomes long and the variation in the length in the circumferential direction becomes large. Therefore, the fluctuation of the length of the cake formation zone, which is still fluid and of which the shape is unstable, immediately affects the part of the cake, and the nonuniformity in the circumferential length and thickness of the part of the cake is caused. It seems that the vibration of the filter tank starts to occur at the same time. More specifically, when this anomaly begins to occur, cakes are generated in an island shape and are distributed unevenly in the circumferential direction in this cake generation zone, and some slurry still flows between these islands. The state of being present was found. Probably because the flow between the narrow islands increases, the slurry flowing toward the mouth of the filtration tank through the islands is also delayed in cake formation. On the contrary, the slow-flowing slurry that collided with the islands was found to cake faster and make the already formed islands or cakes larger and thicker. It seems that these vicious circles call the imbalance of the rotation of the filter tank.

The proposal made by the present inventors was made based on this observation result, and the normally island-shaped cake formed in the cake-forming zone where the fluidity and the shape are unstable is separated from the outside. It is intended to break down by spraying the liquid (cake formation control liquid). When the cake run-off liquid is sprayed from the inside of the filter tank to the part of the cake formed in the island shape, the purpose is to break the island cake and to fluidize again, that is, to return to the same state as the cake generation zone. , The cake runoff liquid is usually sprayed from the nozzle,
If the island-shaped cake is large or if the filtration is advanced, it will not easily collapse, so it is also necessary to spray with a strong jet from the nozzle. In addition, it is convenient to make the distance between the tip of the nozzle and the inner wall of the filtration tank variable so that the state of the island-shaped cake can be dealt with. Further, since this island-shaped cake is not constant in length or position, it is effective to dispose the non-uniform cake quickly over a wide range by installing the nozzles in a plurality of stages in the rotation axis direction of the filtration tank. further,
The direction of spraying the liquid from the nozzle is not particularly limited, but in view of the above purpose, it is effective to spray in the radial direction of the filtration tank, and it is also possible to concentrate only on the island portion or reduce the amount of spray liquid. However, it is preferable.

The cake runoff liquid sprayed from the nozzle is not particularly limited as long as it is a liquid that can fulfill this purpose, because the island-shaped cake must first be broken. However, since it is also important to restore the same state as the cake formation zone and to make a uniform cake again after it has been destroyed as described above, a liquid containing phenol that constitutes the slurry, such as water, an aqueous phenol solution, and bisphenol A.
A containing phenol solution, a mother liquor containing a filtered bisphenol A-containing phenol solution as a main component, and the like are preferable in terms of effects and efficiency.

By spraying the cake runoff liquid (cake formation control liquid), the island cake returns to the state of the cake formation zone, but the island portion filtered and concentrated is made into a slurry again. , There is no significant difference from the density of the original part of the original cake formation zone. Therefore, both of these cake production zones are filtered simultaneously to form cakes. It is observed that the cake is generated in the direction in which the cake that has already been generated is spread and in the direction in which the thickness is increased, while the island-shaped cake is constantly extinguished.

The present invention will be described below with reference to examples.

【Example】

(Example 1) Using a horizontal centrifugal filter separator 1 having an inner diameter of 800 mm, a rotating shaft length of 1600 mm, and an inner volume of 150 liters as shown in FIG.
Centrifugal filtration separation operation was performed at rpm. The bottom of the filtration tank 2 is provided with an extruding plate 2b which is equipped with a dispersion plate 2a and is rotatable and movable in the direction of the rotation axis 3, and an opening 4a near the dispersion plate from the filtration tank mouth side. The supply pipe 4b of the slurry 4 having the is inserted. Further, nozzles 5a, 5b, 5c for ejecting the cake run-off liquid 5 (cake generation control liquid), which are opened toward the inner wall surface of the filtration tank, are provided. A flow rate adjusting valve 5v and a flow meter 5m are attached to each of these nozzles. A crystallizer (not shown) for crystallizing bisphenol A from a phenol solution of bisphenol A is first filled with a phenol aqueous solution which is a solvent, and from this crystallizer, the phenol aqueous solution at 70 ° C. is charged to 32 tons / hour. I started to run dry by charging with. The phenol aqueous solution, which is a feed solution,
All were filtered and collected. The vibration of the filtration tank during the charge and filtration operations was 0.02 cm / sec in terms of speed. Starting the supply of bisphenol A to the crystallizer, the concentration of bisphenol A in the crystallizer and the slurry supplied to the filtration tank
After waiting for the concentration to rise, when the slurry concentration became about 7% by weight, the vibration value of the filtration tank rose sharply to 0.26 cm.
/ Sec. At this time, when the inner wall surface of the filtration tank was observed, island-shaped cake layers were formed nonuniformly in the circumferential direction. The liquid slurry was flowing in the other portions.
Therefore, since the most upstream end of the island-shaped cake layer was between the cake generation control liquid nozzles 5a and 5b, the valve 5v of the cake generation control liquid nozzle 5a was opened to make the cake layer uniform. I tried to adjust the flow rate. The island-shaped cake layer in the area where the cake formation control liquid 5 was sprayed disappeared, and a uniform cake layer was formed between the cake formation control liquid nozzles 5a and 5b. At this time, the flow rate of the cake formation control liquid was 3 tons / hour. The collected mother liquor (bisphenol A-containing phenol solution) was used as the cake formation control liquid.
The vibration was reduced to 0.05 cm / sec in terms of speed. When the slurry concentration increased to the prescribed 30% by weight, the inside of the filtration tank was observed again, and the cake formation control liquid nozzle 5
Since a uniform cake layer was formed upstream of the spray range from a, the cake generation control liquid valve 5v was closed.

(Example 2) The same centrifugal filtration separator and crystallizer as in Example 1 were used, and phenol was supplied to the crystallizer, charging to the filter tank, and idling were conducted under the same conditions as in Example 1. I went there. The vibration of the filtration tank at that time was 0.02 cm / sec in terms of speed as in Example 1. The supply of bisphenol A to the crystallizer was started, and the increase in the bisphenol A concentration in the crystallizer and the slurry concentration supplied to the filtration tank was awaited. When the slurry concentration was 5% by weight, the vibration value of the filtration tank rapidly increased to 0.28 cm / sec. At this time, when the inside of the filtration tank was observed, an island-shaped cake layer was formed nonuniformly in the circumferential direction. The liquid slurry was flowing in the other portions. Since the most upstream end of the non-uniform island-shaped cake layer was between the cake generation control liquid nozzles 5a and 5b, the valve 5v of the cake generation control liquid nozzle 5a was opened to make the cake layer uniform. I tried to adjust the flow rate. The island-shaped cake layer in the area where the cake formation control liquid 5 is sprayed disappears, but the island-shaped cake layer is again formed between the downstream cake formation control liquid nozzles 5b and 5c. Was generated. At this time, the flow rate of the cake formation control liquid was 4 tons / hour. In addition,
The mother liquor recovered was used as the cake formation control liquid. The vibration was 0.29 cm / sec in terms of speed. In order to make the above-mentioned island-shaped cake layer formed between the cake formation control liquid nozzles 5b and 5c uniform, the valve 5v of the cake formation control liquid nozzle 5b was opened to try to adjust the flow rate. The above upstream valve was also adjusted. The island-shaped cake layer in the range where the two cake formation control liquids were sprayed disappeared, and a uniform cake layer was formed. At this time, the flow rate of the cake generation control liquid was 2 tons / hour for 5b and 3 tons / hour for 5c. The recovered mother liquor was used as the cake formation control liquid. The vibration was reduced to 0.09 cm / sec in terms of speed. Slurry concentration increases,
When the inside of the filtration tank was observed again because the amount became 30% by weight, a uniform cake layer was formed upstream of the spray range from the cake formation control liquid nozzle 5a, so both cakes were formed. The production control liquid valve 5v was closed.

(Example 3) The same centrifugal filtration separator and crystallization can as in Example 1 were used, and the same conditions as in Example 1 were used for supplying phenol to the crystallization can, charging the filtration tank, and idling. I went there. The vibration of the filtration tank at that time was 0.02 cm / sec in terms of speed as in Example 1. The supply of bisphenol A to the crystallizer was started, and the increase in the bisphenol A concentration in the crystallizer and the slurry concentration supplied to the filtration tank was awaited. When the slurry concentration was 9% by weight, the vibration value of the filtration tank rapidly increased to 0.22 cm / sec. At this time, when the inside of the filtration tank was observed, an island-shaped cake layer was formed nonuniformly in the circumferential direction. The liquid slurry was flowing in the other portions. Since the most upstream end of the non-uniform island-shaped cake layer was between the cake formation control liquid nozzles 5aa and 5bb, the valve 5v of the cake formation control liquid nozzle 5a was opened to make the cake layer uniform. I tried to adjust the flow rate.
Island-shaped cake in the range where the cake generation control liquid 5 is sprayed
The cake layer disappeared, and a uniform cake layer was formed between the cake formation control liquid nozzles 5a and 5b. At this time, the flow rate of the cake formation control liquid was 4 tons / hour. The recovered mother liquor was used as the cake formation control liquid. The vibration was reduced to 0.06 cm / sec in terms of speed. Slurry concentration increases,
When the inside of the filter tank was observed again because it became the specified 15% by weight, a uniform cake layer was formed downstream of the spray range from the cake formation control liquid nozzle 5a, so the operation was continued. .

[0023]

[Effect of the Invention] When a slurry comprising a phenol solution of bisphenol A and a crystallized bisphenol A phenol adduct is subjected to solid-liquid separation using a centrifugal filtration separator,
Vibrations in the filter tank prevent the vibration of the filter tank by filtering the cake that is abnormally generated in the cake generation zone on the inner wall of the filter tank while flowing away with a phenol solution, etc. Therefore, the solid-liquid separation operation can be stably performed for a long time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of an apparatus used to carry out a method according to the present invention.

[Explanation of symbols]

 1: Centrifugal Filtration Separator 2: Filtration Tank 3: Rotating Shaft 4: Slurry 5: Cake Ejection Liquid (Cake Generation Control Liquid) 5a, 5b, 5c: Cake Generation Control Liquid Spray Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Kodama, 1 Iezaki Kaigan, Ichihara-shi, Chiba Idemitsu Petrochemical Co., Ltd. (72) Kazuyuki Yoshitomi 1, 1 Anesaki Kaigan, Ichihara, Chiba Idemitsu Petrochemical Co., Ltd. In the company

Claims (3)

[Claims] 1. A method for separating a bisphenol A phenol adduct from a slurry containing a bisphenol A phenol adduct crystallized in a phenol solution by filtration through a cake forming zone as a cake by a centrifugal filtration separator. A method for centrifugal filtration separation of a phenol adduct of bisphenol A, characterized in that at least a part of the cake generated in the cake generation zone of the inner wall surface of the filtration tank is filtered and separated while being flowed out with a cake flow-off liquid. . 2. The method of centrifugal filtration separation of a phenol adduct of bisphenol A according to claim 1, wherein the cake flow-off liquid is a phenol-containing solution. 3. The method of centrifugal filtration separation of a phenol adduct of bisphenol A according to claim 1, wherein the cake flow-out liquid is a phenol solution of bisphenol A filtered and separated.