CN212799651U - Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system - Google Patents

Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system Download PDF

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CN212799651U
CN212799651U CN202020733558.1U CN202020733558U CN212799651U CN 212799651 U CN212799651 U CN 212799651U CN 202020733558 U CN202020733558 U CN 202020733558U CN 212799651 U CN212799651 U CN 212799651U
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tank
semi
flash
separator
crystallization
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CN202020733558.1U
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冯克敏
文慧
姜伟
姚石林
李占荣
张森林
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GANSU WENGFU CHEMICAL CO Ltd
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GANSU WENGFU CHEMICAL CO Ltd
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Abstract

The utility model discloses a semi-water-dihydrate phosphoric acid rapid extraction crystallization production system, which comprises a dissolving tank and a crystallization tank, wherein the volume of the dissolving tank is 2-4 times of that of the crystallization tank, the crystallization tank is connected with a flash separator, a liquid phase outlet at the bottom end of the flash separator is connected with a flash separation liquid seal tank, and the upper part of the flash separation liquid seal tank is communicated with the crystallization tank through a pipeline; the lower part of the flash separation liquid seal tank is connected with a semi-water filtering device through a semi-water feeding pump, the semi-water filtering device is connected with a conversion tank, and the conversion tank is connected with a secondary water filtering device through a secondary water feeding pump; the gas phase outlet at the top end of the flash separator is communicated with an entrainment separator, the liquid phase outlet at the lower end of the entrainment separator is communicated with the flash separation liquid seal tank, and the gas phase outlet at the upper end of the entrainment separator is connected with a flash washing system. The system and the process can greatly shorten the material retention time of the whole system, reduce the material retention time by 50 percent, are beneficial to increasing the yield and reducing the energy consumption and the production cost, and are suitable for continuous large-scale production.

Description

Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system
Technical Field
The utility model belongs to the technical field of phosphoric acid production, concretely relates to half water-dihydrate method phosphoric acid fast extraction crystallization production system.
Background
The industrial production of phosphoric acid can be divided into two major categories, one is thermal production and the other is wet production. The wet production is to decompose phosphate rock with strong inorganic acid (such as sulfuric acid, hydrochloric acid, nitric acid, fluosilicic acid, etc.). The wet method has low production cost, but the product contains certain impurities, so the wet method is mainly used for producing phosphate fertilizer at present and partially replaces the raw material of medium-end and low-end phosphorus products produced by a thermal method.
When the conditions such as reaction temperature, the addition amount of sulfuric acid and the like are different, the crystalline form of calcium sulfate usually contains dihydrate CaSO4·2H2O, hemihydrate alpha-CaSO4·1/2H2O and anhydrate CaSO4And (4) three types. The semi-hydrated-dihydrate production process mainly controls reaction conditions to crystallize materials into calcium sulfate hemihydrate firstly, then changes the reaction conditions along with high-concentration phosphoric acid to recrystallize the calcium sulfate hemihydrate into calcium sulfate dihydrate, and the semi-hydrated-dihydrate production process is the semi-hydrated-dihydrate production process.
As is well known, in the domestic wet-process phosphoric acid semi-water-dihydrate production device, the residence time of the whole system materials is mostly controlled to be 9.5-14 h, so that the semi-water-dihydrate extraction tank for large-scale energy production occupies a large area, the device is high in operation energy consumption, and no method for well solving the problem exists at present.
SUMMERY OF THE UTILITY MODEL
The utility model provides a semi-water-dihydrate phosphoric acid rapid extraction crystallization production system, which aims to solve the problems of long retention time and slow production speed of the existing phosphoric acid production materials.
Therefore, the utility model adopts the following technical scheme:
a quick extraction and crystallization production system for phosphoric acid by a semi-water-dihydrate method comprises a dissolving tank, a crystallization tank, a semi-water slurry pump, a flash separator and a mist separator, wherein the volume of the dissolving tank is 2-4 times of that of the crystallization tank, the crystallization tank is connected with the dissolving tank through an overflow pipe, a return pipe and a semi-water slurry circulating pump are connected between the crystallization tank and the dissolving tank, and stirring devices are arranged in the dissolving tank and the crystallization tank;
the top of the flash separator is provided with a gas phase outlet, the upper part of the flash separator is provided with a feed inlet, the bottom of the flash separator is provided with a liquid phase outlet, one end of the semi-aqueous slurry pump is connected with the crystallization tank through a pipeline, the other end of the semi-aqueous slurry pump is connected with the feed inlet of the flash separator, and a slurry injection device is arranged at the feed inlet of the flash separator; a gas phase outlet of the flash separator is connected with the mist separator, a liquid phase outlet of the flash separator is connected with a flash separation liquid seal tank, one part of slurry in the flash separation liquid seal tank is introduced into the crystallization tank through a pipeline, and one part of slurry is sent into the semi-water filtering device through a semi-water feed pump; the semi-water filtering device is connected with a conversion tank, and the conversion tank is connected with a secondary water filtering device through a secondary water feeding pump;
the side part of the mist separator is provided with an air inlet, the top part of the mist separator is provided with a gas phase outlet, the bottom part of the mist separator is provided with a liquid phase outlet, and the liquid phase outlet of the mist separator is connected with a flash separation liquid seal tank and a gas phase outlet which are connected with a flash washing system.
Furthermore, a flue gas recovery pipe is connected above the dissolving tank and the crystallization tank, and the other end of the flue gas recovery pipe is connected with a flue gas washing system.
Further, a stirring device is arranged in the conversion tank.
The beneficial effects of the utility model reside in that:
1. the system and the process can greatly shorten the material retention time of the whole system, reduce the material retention time by 50 percent, are beneficial to increasing the yield and reducing the energy consumption and the production cost, and are suitable for continuous large-scale production;
2. the process can greatly reduce the slurry content in the finished phosphoric acid, effectively improve the quality of the phosphoric acid and replace part of low-grade thermal phosphoric acid products;
3. the water in the process is recycled, the emission is reduced, and the consumption of water resources is reduced.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention;
in the figure: 1-a dissolving tank, 2-a crystallizing tank, 3-a semi-water slurry pump, 4-a flash separator, 5-an entrainment separator, 6-a flash separation liquid seal tank, 7-a semi-water feed pump, 8-a semi-water slurry circulating pump, 9-a semi-water filtering device, 10-a converting tank, 11-a semi-water feed pump and 12-a semi-water filtering device.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings:
as shown in the figure, the semi-water-dihydrate phosphoric acid rapid extraction crystallization production system comprises a dissolving tank 1 and a crystallization tank 2, wherein the volume of the dissolving tank 1 is 2-3 times that of the crystallization tank 2, and the crystallization tank 2 is connected with the dissolving tank 1 through an overflow pipe. Since the semi-water reaction is carried out in the dissolution tank 1, P of the semi-water slurry in the dissolution tank 12O5The concentration is as high as more than 38%, and the influence of impurity ions causes large viscosity, high saturation, poor stirring effect and slow reaction speed of the reaction slurry. After increasing the volume of the dissolving tank 1, the reaction time can be prolonged, higher extraction rate can be obtained, and the semi-water crystal in the crystallizing tank 2 can grow further under the condition of proper excess SO3, SO that the semi-water crystal can be converted into semi-water crystal which is easy to filter.
A return pipe and a semi-water slurry circulating pump 8 are connected between the crystallization tank 2 and the dissolving tank 1, and the semi-water slurry circulating pump 8 can convey slurry in the crystallization tank 2 to the dissolving tank 1 through the return pipe. All be equipped with agitating unit in dissolving tank 1 and the crystallizer 2, the top of dissolving tank 1 and crystallizer 2 still is connected with flue gas recovery pipeline, and flue gas recovery pipeline's the other end is connected with flue gas tail-washing system.
The top of the flash separator 4 is provided with a gas phase outlet, the upper part of the flash separator 4 is provided with a feed inlet, the bottom of the flash separator 4 is provided with a liquid phase outlet, one end of the semi-water slurry pump 3 is connected with the crystallization tank 2 through a pipeline, the other end of the semi-water slurry pump is connected with the feed inlet of the flash separator 4, and a slurry injection device is arranged at the feed inlet of the flash separator 4; a gas phase outlet of the flash separator 4 is connected with the mist separator 5, a liquid phase outlet of the flash separator 4 is connected with the flash separation liquid seal tank 6, one part of slurry in the flash separation liquid seal tank 6 is introduced into the crystallization tank 2 through a pipeline, and one part of slurry is sent into the semi-water filtering device through the semi-water feeding pump 7; the semi-water filtering device is connected with a conversion tank 10, a stirring device is arranged in the conversion tank 10, and the conversion tank 10 is connected with a secondary water filtering device 12 through a secondary water feeding pump 11.
The side part of the mist separator 5 is provided with an air inlet, the top part is provided with a gas phase outlet, the bottom part is provided with a liquid phase outlet, the liquid phase outlet of the mist separator 5 is connected with a flash separation liquid seal tank 6, and the gas phase outlet is connected with a flash washing system.
A semi-water-dihydrate phosphoric acid rapid extraction crystallization production process is carried out by the equipment, and comprises the following steps and principles: adding the crushed phosphorite raw material and concentrated sulfuric acid into the dissolving tank 1, fully stirring to enable the material to circularly react, and reacting the phosphorite under the decomposition action of the concentrated sulfuric acid to generate calcium sulfate hemihydrate. The reaction formula is as follows:
Ca5F(PO4)3+5H2SO4+2*1/2H2O=3H3PO4+5CaSO4·1/2H2O ↓+HF↑
after the reaction, the slurry overflows into a crystallization tank 2, excessive concentrated sulfuric acid is added into the crystallization tank 2, and the slurry promotes the calcium sulfate hemihydrate crystal to grow continuously under the action of the excessive concentrated sulfuric acid and active silica; the residence time of the materials in the dissolving tank is controlled to be 2-2.5 h, and the residence time in the crystallization tank is controlled to be 1-1.5 h.
The slurry in the crystallization tank 2 enters a flash separator 4 through a semi-water slurry pump 3 for cooling, and the pressure of the flash separator 4 is controlled to be 10-15 KPa; the slurry is sprayed into the flash separator 4 by means of a spraying device. The slurry forms liquid film double effect evaporation in the flash separator 4, which not only increases the slurry evaporation area, but also eliminates the bumping phenomenon caused by rapid slurry evaporation and temperature reduction; meanwhile, the vacuum degree is reduced, and the entrainment accompanying the evaporation gas is reduced. After passing through the flash separator 4, the temperature difference of the semi-water slurry is reduced from more than 95 ℃ to less than 70 ℃, and the temperature difference of the semi-water slurry can be controlled within 25 ℃. The cooled fluorine-containing gas enters a mist separator 5 through a gas phase outlet for further gas-liquid separation, and the separated gas enters a tail gas washing system; the cooled slurry flows into a flash separation liquid seal tank 6 from a liquid phase outlet under the action of gravity, one part of the slurry in the flash separation liquid seal tank 6 flows back to a crystallization tank, the other part of the slurry is sent into a semi-water filtering device for filtering through a semi-water feeding pump 7, semi-water gypsum and filtered acid are obtained after filtering, the filtered acid is the product phosphoric acid, and the semi-water gypsum enters a conversion tank 10; in the conversion tank 10, the hemihydrate gypsum is subjected to a dihydrate reaction under the action of concentrated sulfuric acid. The reaction formula is as follows:
CaSO4·1/2H2O+1/2H2O=CaSO4·2H2O↓+Q
and (3) feeding the reacted slurry into a dihydrate filtering device through a dihydrate feeding pump for filtering, separating to obtain dihydrate gypsum, controlling the reaction time of the materials in the conversion tank to be 1.5-2 h, and controlling the total retention time of the materials in the system to be 5.5-6 h.
Compared with the conventional process, the inlet of the flash separator 4 is positioned at the upper part, and slurry moves from top to bottom after entering, so that gas-liquid separation is facilitated, and the separation speed and the separation effect can be greatly improved. The concentrated sulfuric acid in the system is the concentrated sulfuric acid of 98.5 percent wt, the utility model discloses the phosphoric acid concentration of technology output is more than 45 percent wt, and output gypsum dry basis P2O5The content of (A) is less than 0.25 wt%, the total reaction time is shortened to 5.5-6 h, and the technical effect is very obvious.
It should be noted that the above are only some embodiments of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims (3)

1. A semi-water-dihydrate phosphoric acid rapid extraction crystallization production system is characterized in that: the device comprises a dissolving tank, a crystallization tank, a semi-water slurry pump, a flash separator and a mist separator, wherein the volume of the dissolving tank is 2-4 times of that of the crystallization tank, the crystallization tank is connected with the dissolving tank through an overflow pipe, a return pipe and a semi-water slurry circulating pump are connected between the crystallization tank and the dissolving tank, and stirring devices are arranged in the dissolving tank and the crystallization tank;
the top of the flash separator is provided with a gas phase outlet, the upper part of the flash separator is provided with a feed inlet, the bottom of the flash separator is provided with a liquid phase outlet, one end of the semi-aqueous slurry pump is connected with the crystallization tank through a pipeline, the other end of the semi-aqueous slurry pump is connected with the feed inlet of the flash separator, and a slurry injection device is arranged at the feed inlet of the flash separator; a gas phase outlet of the flash separator is connected with the mist separator, a liquid phase outlet of the flash separator is connected with a flash separation liquid seal tank, one part of slurry in the flash separation liquid seal tank is introduced into the crystallization tank through a pipeline, and one part of slurry is sent into the semi-water filtering device through a semi-water feed pump; the semi-water filtering device is connected with a conversion tank, and the conversion tank is connected with a secondary water filtering device through a secondary water feeding pump;
the side part of the mist separator is provided with an air inlet, the top part of the mist separator is provided with a gas phase outlet, the bottom part of the mist separator is provided with a liquid phase outlet, and the liquid phase outlet of the mist separator is connected with a flash separation liquid seal tank and a gas phase outlet which are connected with a flash washing system.
2. The system for producing phosphoric acid by semi-hydrated-dihydrate method through rapid extraction and crystallization as claimed in claim 1, wherein a flue gas recovery pipe is connected above the dissolving tank and the crystallization tank, and the other end of the flue gas recovery pipe is connected with a flue gas washing system.
3. The system for producing phosphoric acid by semi-hydrated-dihydrate through rapid extraction and crystallization as claimed in claim 1, wherein a stirring device is arranged in the conversion tank.
CN202020733558.1U 2020-05-07 2020-05-07 Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system Expired - Fee Related CN212799651U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111591965A (en) * 2020-05-07 2020-08-28 甘肃瓮福化工有限责任公司 Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system and process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111591965A (en) * 2020-05-07 2020-08-28 甘肃瓮福化工有限责任公司 Semi-water-dihydrate phosphoric acid rapid extraction crystallization production system and process

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Granted publication date: 20210326