CN201276426Y - Sodium sulphate decahydrate crystallizer - Google Patents

Abstract

The utility model discloses a sodium sulfate decahydrate crystallizer, which comprises a cylinder body, a material outlet pipe placed at the lower part of the side wall of the cylinder body, a speed regulating motor and a reducer installed at the top of the cylinder body, and a Agitator transmission shaft, one end of the agitator transmission shaft is connected to the reducer, and the other end is equipped with agitator blades; a cylindrical guide tube is installed inside the cylinder, and the upper opening of the guide tube is set below the liquid flow surface , there is a gap between the lower opening and the bottom of the cylinder, the inner diameter of the diversion cylinder is smaller than the inner diameter of the cylinder, and the agitator blade is placed inside the diversion cylinder; the bottom edge of the cylinder is an inverted cone, and there is a positive cone-shaped protrusion in the center of the bottom; 3 to 5 vertical baffles are evenly distributed on the inner wall of the cylinder, and the height of the baffles is higher than that of the guide cylinder. The sodium sulfate decahydrate crystallizer of the utility model adopts a unique structural design, so that the average particle size of the sodium sulfate decahydrate crystal reaches more than 0.25 mm, and has a long operation period, low energy consumption, low cost, and is easy to operate.

Description

A kind of sodium sulfate decahydrate crystallizer

technical field

The utility model belongs to the technical field of crystallization, and relates to a crystallizer, in particular to a sodium sulfate decahydrate crystallizer used for denitrification by brine freezing method.

Background technique

There are large-scale rock salt deposits in Sichuan, Hubei, Jiangxi, Jiangsu and other places in my country, which provide resource guarantee for the local development of salt chemical industry. However, rock salt is often accompanied by Glauber's salt. The presence of Glauber's salt not only restricts the use of salt, but also causes environmental pollution if it is not handled properly. The principle of the freezing denitrification process currently used is to use the difference in the components of the co-saturated solution of sodium chloride and sodium sulfate at different temperatures. From the phase diagram of the NaCl-Na ₂ SO ₄ -H ₂ O ternary system, it can be seen that when When the temperature is lower than 17.9°C _, the solubility of Na ₂ SO ₄ decreases greatly with the decrease of temperature. When the temperature is as low as -5°C _, it reaches _{the highest} efficiency point _. The form crystallizes out to achieve the purpose of separation. When the existing technology separates salt and nitrate, the content of sodium sulfate in the brine is generally greater than 7.5g/L, which affects the quality of the brine. The main reason for this phenomenon is that there is no specially designed sodium sulfate decahydrate crystallizer in the existing process. Only an intermediate circulation tank and a refrigeration heat exchanger are used to circulate and freeze the brine of the material to -5°C. When the material cools down, the sulfuric acid Sodium reaches supersaturation in the solution, and the crystallized sodium sulfate decahydrate particles are fine, and the supersaturation of sodium sulfate in the material separated by the subsequent settler is still high, and the material still precipitates sodium sulfate decahydrate in the settler Crystal nuclei and fine crystals, fine sodium sulfate decahydrate crystals form a large amount of floating nitric acid, which makes it difficult to separate sodium sulfate decahydrate crystals from brine, and the separation equipment is bulky. Due to the incomplete separation, the separated brine still contains many fine sodium sulfate decahydrate crystals, resulting in a sodium sulfate content greater than 7.5g/L in the brine, which affects the quality of the brine, and then affects the use of brine in the salt chemical industry and the two Use in the alkali industry.

Contents of the invention

The technical problem to be solved by the utility model is to provide a sodium sulfate decahydrate crystallizer for frozen denitrification of brine.

In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is:

A sodium sulfate decahydrate crystallizer, comprising a cylinder, a material outlet pipe placed on the lower part of the side wall of the cylinder, a speed-regulating motor and a reducer installed on the top of the cylinder, and an agitator drive shaft vertically placed inside the cylinder, One end of the drive shaft of the agitator is connected to the reducer, and the other end is equipped with the agitator blade; inside the cylinder is installed a cylindrical guide tube with only side walls, no upper cover and lower bottom. The mouth is set below the liquid flow surface, and there is a gap between the lower opening of the diversion cylinder and the bottom of the cylinder, the inner diameter of the diversion cylinder is smaller than the inner diameter of the cylinder, and the agitator blade is placed inside the diversion cylinder; the bottom edge of the cylinder is inverted cone, There is a positive conical protrusion in the center of the bottom, and the top of the positive conical protrusion is opposite to the center of the guide cylinder; 3 to 5 vertical baffles are evenly distributed on the inner wall of the cylinder, and the height of the baffles is higher than that of the guide cylinder.

Among them, 3 to 5 refrigerated return pipes are evenly distributed on the upper part of the side wall of the cylinder, and a circular collecting pipe is surrounded on the outside of the cylinder. The circular collecting pipe is connected with the refrigerated heat exchange device outside the crystallizer. It communicates with the round collecting pipe through the pipe.

Among them, the bottom of the cylinder is provided with a crystallizer drain.

Wherein, the guide cylinder is fixed inside the cylinder body through the upper support and the lower support. The upper support is three evenly distributed strip parts, one end of which is connected to the side wall of the cylinder body, and the other end is connected to the upper part of the side wall of the guide tube. The lower support is three evenly distributed strip parts, one end of which is connected to the bottom of the cylinder body, and the other end is connected to the lower part of the side wall of the guide tube.

When the crystallizer is in use, the materials to be processed are added to the crystallizer of the utility model. When the liquid level of the materials reaches and exceeds the freezing return outlet pipe, the materials are sent to the refrigeration heat exchanger by a pump for cyclic freezing, and the temperature drops. When the solubility of sodium sulfate in the material reaches supersaturation, sodium sulfate decahydrate crystals begin to separate out to form crystal nuclei in the material. Due to the effect of stirring, the material circulates and mixes in the space formed by the middle of the diversion cylinder of the crystallizer of the utility model and the outer side of the diversion cylinder and the cylinder body. Sodium sulfate in the material around the crystal nucleus precipitates on the crystal nucleus to form fine crystals, and the supersaturation tends to be saturated. Due to the effect of stirring, the saturated material around the fine crystal is continuously replaced by the material farther away, so that the material around the fine crystal reaches supersaturation again, and new sodium sulfate is precipitated on the fine crystal. This process continues continuously, and the crystal keep growing. Due to the effect of stirring, the material circulates inside and outside the guide tube. The double-cone structure and the baffle on the wall of the tube can make the material form a stable circulating flow state, so that the crystals in the material are suspended in the material. By adjusting the stirring The rotation speed of the device controls the circulation intensity of the material. When the crystal particles reach a certain level, due to the increase in weight, the circulation of the material will no longer be able to suspend the large crystals, and all the large crystals will be more concentrated at the bottom of the circulating crystallizer. Therefore, the material that meets the requirements at the bottom of the circulating crystallizer is drawn out and sent to separation and sedimentation for treatment. The average particle size of sodium sulfate decahydrate crystals in these materials reaches more than 0.25 mm, basically eliminates the supersaturation of sodium sulfate decahydrate crystals in the mother liquor, no fine crystal particles are produced in the settler, and the sodium sulfate decahydrate crystal particles settle completely. The sodium sulfate content in the overflowed clear liquid after separation is less than or equal to 7.5g/L.

Beneficial effects: the sodium sulfate decahydrate crystallizer of the utility model adopts a unique structural design, so that the average particle diameter of the sodium sulfate decahydrate crystal can reach more than 0.25mm. It can be applied to the crystallization and removal of sodium sulfate in the denitrification process of brine freezing method, replacing the intermediate circulation tank in common processes, fully ensuring the separation of sodium chloride and sodium sulfate in brine, and meeting the quality requirements of the soda industry for sodium chloride brine. The rock salt resources associated with salt and nitric acid can be comprehensively utilized with lower energy consumption. The crystallizer of the utility model has the advantages of long operation period, low energy consumption, low cost and easy operation, and belongs to a green device free from three wastes pollution, and is especially suitable for producing caustic soda by using rock salt resources to realize soda production with brine.

Description of drawings

Fig. 1 is the front view of the utility model sodium sulfate decahydrate crystallizer.

Fig. 2 is the top view of the utility model sodium sulfate decahydrate crystallizer.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail.

Fig. 1 is the front view of the utility model sodium sulfate decahydrate crystallizer, and Fig. 2 is its top view.

As can be seen from the figure, the sodium sulfate decahydrate crystallizer of the present utility model comprises a cylinder 4, a material outlet pipe 16 placed on the bottom of the cylinder 4 side walls, a speed-regulating motor 10 and a speed reducer 9 installed on the top of the cylinder 4, The agitator transmission shaft 12 placed vertically inside the cylinder body 4, one end of the agitator transmission shaft 12 is connected with the speed reducer 9, and the other end is equipped with the agitator paddle 15, and the agitator part (including the speed regulating motor 10, the speed reducer 9, The agitator transmission shaft 12 and the agitator blade 15) are fixed on the top of the cylinder body 4 by the top bracket 7.

A cylindrical guide tube 14 with only side walls, no upper cover and lower bottom is installed inside the cylinder body 4. The upper opening of the guide tube 14 is located below the liquid flow surface, and the lower opening of the guide tube 14 is connected to the tube. There is a gap at the bottom of the body 4 , the inner diameter of the guide tube 14 is smaller than the inner diameter of the cylinder body 4 , and the agitator blade 15 is placed inside the guide tube 14 . The guide cylinder 14 is fixed inside the cylinder body 4 through the upper support 13 and the lower support 2 . The upper support 13 is three evenly distributed strip parts, one end of which is connected to the side wall of the cylinder body 4, and the other end is connected to the upper part of the side wall of the guide tube 14. The lower support 2 is three evenly distributed strip parts, one end of which is connected to the bottom of the cylinder body 4 , and the other end is connected to the lower part of the side wall of the guide tube 14 .

The edge of the bottom of the cylinder body 4 is inverted conical, and there is a positive conical protrusion 1 in the center of the bottom, which is W-shaped when viewed from the side. 1 top is opposite to the center of the guide tube 14 .

Four vertical baffles 3 are evenly distributed on the inner wall of the cylinder body 4 , and the height of the baffles 3 is higher than that of the guide tube 14 .

Four refrigerated return pipes 6 are evenly distributed on the upper part of the side wall of the cylinder 4, and a circular collection pipe 5 is surrounded on the outside of the cylinder 4, and the circular collection pipe 5 is connected with the refrigeration heat exchange device outside the crystallizer, and all the frozen return pipes 6 The outlet of the outlet is connected to the circular collecting pipe 5 through a pipeline, and after the overflowed material is collected in the circular collecting pipe 5, it is pumped into the refrigeration heat exchange device for circulation and cooling.

The bottom of the cylinder 4 is provided with a crystallizer drain 18 .

The utility model is applied to the crystallization and removal of sodium sulfate in the brine freezing method denitrification process. The specific operation process is as follows: the brine temperature is 25°C, the flow rate is 20m ³ /h, the sodium chloride in the brine is 280-290g/L, sulfuric acid The sodium content is 20-35g/L. The brine enters the crystallizer after pre-cooling at 10°C. The brine circulates and freezes in the crystallizer and the refrigeration heat exchanger. The crystallization temperature is -5°C. The crystallized salt slurry is sent to the settler for gravity Settling, the supernatant liquid overflowing from sedimentation contains 280-290g/L of sodium chloride and 6.7g/L of sodium sulfate, and the brine of the supernatant liquid is used for subsequent processes, and the crystal grain size of Na ₂ SO ₄ ·10H ₂ O is 0.25mm.

Claims (6)

1, a kind of sodium sulfate decahydrate crystallizer, comprise cylinder body (4), be placed in the material outlet pipe (16) of cylinder body (4) side wall bottom, be installed in the speed-regulating motor (10) of cylinder body (4) top ) and reducer (9), the agitator transmission shaft (12) placed vertically inside the cylinder (4), one end of the agitator transmission shaft (12) is connected with the reducer (9), and the other end is equipped with agitator blades (15), it is characterized in that cylinder body (4) inside is equipped with a cylindrical guide tube (14) that only has side wall, no upper cover and lower bottom, and the upper mouth of the guide tube (14) is located at Below the liquid flow surface, there is a gap between the lower opening of the diversion cylinder (14) and the bottom of the cylinder (4), the inner diameter of the diversion cylinder (14) is smaller than the inner diameter of the cylinder (4), and the agitator blade (15) is placed Inside the cylinder (14); the bottom edge of the cylinder body (4) is in an inverted conical shape, and there is a positive conical protrusion (1) in the center of the bottom, and the top of the positive conical protrusion (1) is opposite to the center of the guide cylinder (14); Three to five vertical baffles (3) are evenly distributed on the inner wall of the cylinder body (4), and the height of the baffles (3) is higher than that of the guide tube (14). 2. The sodium sulfate decahydrate crystallizer according to claim 1, characterized in that 3 to 5 freezing reflux pipes (6) are evenly distributed on the upper part of the side wall of the cylinder (4), and there is a tube around the outside of the cylinder (4). A circular collecting pipe (5), the circular collecting pipe (5) is connected with the freezing heat exchange device outside the crystallizer, and the outlets of all freezing return pipes (6) are connected with the circular collecting pipe (5) through pipelines. 3. The sodium sulfate decahydrate crystallizer according to claim 1, characterized in that the bottom of the cylinder (4) is provided with a crystallizer drain (18). 4. The sodium sulfate decahydrate crystallizer according to claim 1, characterized in that the draft tube (14) is fixed inside the cylinder body (4) through the upper support (13) and the lower support (2). 5. The sodium sulfate decahydrate crystallizer according to claim 4, characterized in that the upper support (13) is 3 evenly distributed strip parts, and one end of the strip parts is connected to the cylinder (4) side wall Link to each other, and the other end links to each other with the upper part of the side wall of the guide tube (14). 6. The sodium sulfate decahydrate crystallizer according to claim 4, characterized in that the lower support (2) is 3 evenly distributed strip parts, one end of which is connected to the bottom of the cylinder (4) , the other end links to each other with the lower part of the side wall of the draft tube (14).

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