JPH06107580A - Production of bisphenol a prill - Google Patents

Abstract

PURPOSE:To obtain bisphenol A prill with favorable granular size in higher yield along with reduced by-product powder. CONSTITUTION:A bisphenol A melt is dripped through the grating at the upper part of a granulation column, while a cooling gas is allowed to flow from the lower part upward to cool and solidify the droplets to obtain the objective bisphenol A prill. In this case, when the theoretical final falling speed for the mean granular diameter of the bisphenol A prill falling under solidification is denoted as Vp, the maximum flow speed of the cooling gas Vg is maintained so as to satisfy the relationship: 0.1Vp<Vg<0.8Vp.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing bisphenol A prill.

[0002]

BACKGROUND OF THE INVENTION Bisphenol A has a chemical name of 2,2-
It is a normal temperature solid compound of bis (4-hydroxyphenyl) propane, and is a small spherical particle usually called prill,
Obtained in the form of flakes and crystals. Needless to say, it is desirable that these have the same shape and particle size from the viewpoint of handleability. From the aspect of shape uniformity, prills obtained by solidifying droplets are the most excellent, and this is the mainstream.

A method for producing bisphenol A prill is U
As described in SP3518329, JP-A No. 2-501921 and the like, all of these control shape, strength and the like by controlling solidification conditions such as the presence of seed crystals. However, even if such a method is adopted, crushing may occur and dust may be generated. Further, Japanese Patent Publication No. 47-8060 describes that a bisphenol A prill is produced by dropping a droplet of bisphenol A from a granulation tower and bringing it into contact with a cooling gas. There is. In such a granulation tower, it is effective not only to regulate the gas flow but also to effectively collect and remove the solidified prills by narrowing the lower part to provide a cone part. It was found that the prills piled up on the ground and formed bridges, resulting in the crushing of the prills.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a bisphenol A prill with less crushing of prill in a granulation tower.

[0005]

The present invention is directed to a bisphenol
The molten solution of A is dripped from the upper plate of the granulation tower, and a cooling gas is flowed from the lower part to the upper part to cool and solidify the liquid droplets to produce bisphenol A prills. Flow rate Vg of the cooling gas, where Vp is the theoretical final drop velocity of the average particle size of the bisphenol A prill falling
Is held under the condition of 0.1 Vp <Vg <0.8 Vp for granulation, and a method for producing bisphenol A prill.

The bisphenol A to which the present invention is applied may be obtained in the production process, or may be a powdery recovered product or a commercially available product. In the present invention, such bisphenol A is melted and dropped as droplets from the granulation tower to obtain prills. Hereinafter, the present invention will be described with reference to FIG.
Will be described.

In FIG. 1, 1 is an inlet pipe for a bisphenol A melt, 2 is a plate, 3 is an inner space of a granulating tower, 4 is a core.
Section, 5 is a prill outlet, 6 is a cooling gas inlet,
Reference numeral 7 is a cooling gas outlet. The liquid droplets falling from the perforated plate 2 come into countercurrent contact with the cooling gas in the space 3, are cooled and solidified, and are completely solidified in the vicinity of the cone portion 4, that is, prills. This prill drops in the cone part 4 and is taken out from the take-out port in the lower part of the granulation tower. Further, the cooling gas is supplied from the inlet 6, is contacted with the droplets or prills while being passed through the cone portion 4 and the space 3 and is given heat, and becomes a warm gas and is exhausted from the outlet 7. The exhausted gas can be reused by cooling after separating the powder. Further, an inert gas such as nitrogen is desirable as the gas.

The hole diameter of the perforations is determined by the intended prill diameter, but is usually determined so that the prill diameter is about 0.5 to 5 mm, preferably about 0.8 to 3 mm.
The height of the granulation tower is such that the unsolidified substance decreases as the space 3 is sufficient and the productivity increases, but in the case of a normal prill diameter, the space 3 is preferably 10 m or more and less than 30 m. . The cone portion 4 is provided at a position where the liquid droplets are solidified, and is configured so that the diameter becomes smaller toward the lower part. Preferably, the diameter of the tip of the cone portion 4 is continuously reduced so that the diameter thereof is about 2/3 to 1/4 of the diameter of the space 3.

In the present invention, the theoretical final drop velocity Vp at the average particle size of the prill formed in the space 3 and the flow velocity Vg of the cooling gas are maintained so as to satisfy the following equation. 0.1Vp <Vg <0.8Vp, preferably 0.2Vp
<Vg <0.7Vp Here, the terminal falling velocity is a value calculated on the assumption that there is no gas flow, and is determined by the prill diameter, density, and the like.
Since the diameter of the prills varies, the theoretical final falling velocity at this average particle diameter is Vp. The flow rate of the cooling gas is
It is the flow velocity at the tip of the cone portion 4 with the smallest diameter. If this Vg is too large, the prills are likely to be deposited on the cone portion 4, and crushing, clogging, etc. occur. On the other hand, if it is too small, the relative velocity of the prill becomes high, the contact time with the cooling gas cannot be taken, and the prill is stuck to the cone portion to reduce the productivity of the prill.

[0010]

By setting the maximum flow rate of the cooling gas within the above range, the fall of the prills is not hindered, thereby preventing accumulation and blockage in the cone portion, and
It is considered that the prills also prevent the formation of a fluidized bed and fracture.

[0011]

EXAMPLES Examples of the present invention are shown below. In addition, a compounding rate shows a weight part and% shows weight%. Example 1 Using the experimental apparatus shown in FIG. 1, bisphenol A (purity 99.935%) was heated to 170 ° C. and melted, and this was dripped from a perforated plate having many holes of about 0.8 mm diameter. Then, droplets were formed, dropped while being in countercurrent contact with the cooling gas, and solidified to produce bisphenol A prill. The space 3 of the experimental apparatus has a diameter of 290 mm, the tip of the cone 4 has a diameter of 150 mm, and the height from the top of the cone to the tip is 1
90 mm, the inclination of the cone is 60 °. In addition, the height until the droplet solidifies and reaches the upper end of the cone is 12.5.
m. Charge nitrogen gas from the cooling gas inlet,
The gas flow velocity in the space 3 was set to 1.2 m / s, and the flow velocity at the tip of the cone was set to 4.5 m / s. Further, the prill was dropped at a rate of 230 g / min. Under these conditions, no fluidized bed was formed in the cone and crushing of the prill was small. The particle size distribution of the obtained prill is shown in Table 1.

Comparative Example 1 The diameter of the tip of the cone of the experimental apparatus used in Example 1 was 10
The same experiment as in Example 1 was conducted except that the flow velocity at the tip of the cone was 8.8 m / s and the gas flow velocity in the space 3 was 1.2 m / s. . Under these conditions, formation of a fluidized bed in the cone was observed, and the prills were often crushed. The particle size distribution of the obtained prill is shown in Table 1.

Comparative Example 2 The diameter of the tip of the cone portion of the experimental apparatus used in Example 1 was set to 10
The experiment was conducted in the same manner as in Example 1 except that the flow velocity at the tip of the cone was 5.9 m / s and the gas flow velocity in the space 3 was 0.8 mm / s. . Under this condition, formation of a fluidized bed at the corner was slightly observed. The particle size distribution of the obtained prill is shown in Table 1.

[0014]

[Table 1]

[0015]

According to the production method of the present invention, the proportion of bisphenol A prill having an appropriate particle size can be increased.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a cross section of a granulation tower.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Introductory pipe 2 ... Perforation 4 ... Corn part 6 ... Gas inlet 7 ... Gas outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Yoshitsu 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture, Chiyoda Kakoh Construction Co., Ltd. (72) Katsumi Tozaki Tsurumi-chuo, Tsurumi-ku, Yokohama-shi, Kanagawa 2-12-1, Chiyoda Kakoh Construction Co., Ltd. (72) Inventor Makoto Nomura 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama Tsurumi-ku, Kanagawa Prefecture (72) Inventor Mamoru Morita Fukuoka Prefecture 7-12-601 Takamine-cho, Kokurakita-ku, Kitakyushu City (72) Inventor Akio Yamamoto 2-1-11, Ibori, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture (72) Nobuo Tani, Katatota, Kamisaigo, Fukuma-cho, Munakata-gun, Fukuoka 28 −43 (72) Inventor Takamasa Minami 2-29, Kuchiamihigashi, Kokuraminami-ku, Kitakyushu City, Fukuoka Prefecture

Claims (1)

[Claims] 1. A molten solution of bisphenol A is dripped from the upper plate of the granulation tower, and a cooling gas is flown from the lower part toward the upper part to cool and solidify the liquid droplets to obtain bisphenol A prill. When the theoretical final falling speed at the average particle size of the bisphenol A prill that solidifies and drops is Vp, the flow rate Vg of the cooling gas is 0.1 Vp <Vg <
A method for producing bisphenol A prill, which comprises granulating while maintaining a condition of 0.8 Vp.