CN102020301A - Aluminium hydroxide drying system - Google Patents

Abstract

The invention discloses an aluminium hydroxide drying system in order to solve the problems that aluminium hydroxide air drying requires long process route, has low production efficiency and consumes considerable energy, and that water in dried aluminium hydroxide cannot meet the requirements of aluminium hydroxide production with a dry method. The aluminium hydroxide drying system comprises a blower, a hot blast heater, a flash dryer, a double-swirl dryer, a cyclone separator, a material bin, a cloth bag dust remover and a draft fan, wherein the blower is connected with the hot blast heater, the hot blast heater is connected with the flash dryer, the flash dryer is connected with the double-swirl dryer, the double-swirl dryer is connected with the cyclone separator, the cyclone separator is connected with the cloth bag dust remover, and the cloth bag dust remover is connected with the draft fan. The invention has the advantages of short process flow, fully closed drying process, no impurity intrusion, high finished product quality, excellent operation environment, high thermal efficiency, short drying time and excellent energy saving effect.

Description

Aluminum hydroxide drying system

technical field

The invention relates to an aluminum hydroxide drying system.

Background technique

Aluminum hydroxide is one of the main raw materials for dry-process aluminum fluoride production, and its moisture content is 5-10%. The dry-process aluminum fluoride production process requires that raw material aluminum hydroxide must be dried to make the moisture content less than 0.1%. in production.

The usual method of drying aluminum hydroxide is air drying. The heated hot air flows in the pipeline at high speed, and the wet material enters the pipeline and is taken to the outlet of the pipeline by the high-speed airflow; in this process, due to the convective heat and mass transfer, water Steam is evaporated. Since the material is dispersed by the high-speed airflow after entering the pipeline, the two are fully mixed, and the gas-solid phase is separated by a cyclone separator at the pipeline outlet, and the exhaust gas is discharged through the exhaust fan. Regardless of the initial moisture content of the material, the moisture content of the general material is reduced to 0.3% to 0.5%, and it is not easy to obtain a dry product with a lower moisture content. Apparently it cannot meet the requirement of dry process aluminum fluoride production, the moisture content of aluminum hydroxide being less than 0.1% after drying. In addition, air drying requires a high-efficiency dust collection device, otherwise the dust carried by the exhaust gas will cause a lot of waste and pollute the environment; for materials that are agglomerated and difficult to disperse, a feeding device with good performance is required , Sometimes an additional crushing process is required; the flow resistance drop of the airflow drying system is relatively large, generally 3000--4000Pa, and a high-pressure or medium-pressure fan must be selected, and the power consumption is relatively large.

Contents of the invention

The purpose of the present invention is to provide an aluminum hydroxide drying system to solve the problems of long process route, low production efficiency, and large energy consumption in air-drying aluminum hydroxide, and the moisture content of aluminum hydroxide after drying is difficult to meet the production requirements of dry-process aluminum fluoride. The problem.

The invention includes a blower, a hot blast stove, a flash dryer, a double swirl dryer, a cyclone separator, a silo, a bag filter, and an induced draft fan. The blower is connected to the hot blast stove, and the hot blast stove is connected to the flash dryer. The dryer is connected to the double-swirl dryer, the double-swirl dryer is connected to the cyclone separator, the cyclone separator is connected to the bag filter, and the bag filter is connected to the induced draft fan.

The invention has the advantages of short technological process, fully closed drying process, no impurities, high product quality, good operating environment, high thermal efficiency, short drying time and good energy-saving effect. It integrates the crushing, dispersing, boiling drying, air drying and grading process of materials, and operates continuously; the equipment is small in size, strong in drying strength, simple and reliable in structure, and easy to operate and maintain. In particular, the moisture after drying the aluminum hydroxide is less than 0.1%, and the components after drying the aluminum hydroxide meet the production requirements through production practice.

The material drying time of the invention is short, and the material drying process can be completed within 10 seconds. Flash drying is more energy efficient than airflow drying. Flash drying, drying 1 ton of aluminum hydroxide requires 90m ³ of gas, equivalent to 16.07kg of standard coal; airflow drying, drying of 1 ton of aluminum hydroxide requires 115m ³ of gas, equivalent to 20.54kg of standard coal. To dry 1 ton of aluminum hydroxide, flash drying saves 21.76% of standard coal compared with airflow drying. The conversion coefficient of gas is calculated at 0.1786kg/m ³ .

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a schematic structural view of the flash dryer in the present invention.

Detailed ways

The following embodiments can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

As shown in Figure 1, the present invention comprises blower 1, hot blast furnace 2, flash dryer 3, double-swirl dryer 4, cyclone separator 5, silo 6, bag filter 7, induced draft fan 8, blower 1 and The hot blast stove 2 is connected, the hot blast stove 2 is connected with the flash dryer 3, the flash dryer 3 is connected with the double swirl dryer 4, the double swirl dryer 4 is connected with the cyclone separator 5, and the cyclone separator 5 is connected with the bag dust removal The device 7 is connected, and the bag filter 7 is connected with the induced draft fan 8.

Fig. 2 shows the structure of the flash dryer in the present invention, the bottom shaft 31 of the flash dryer 3 is provided with a material breaker 34, and the flash dryer 3 is provided with a central cylinder 35 inside. The middle and upper part of the central cylinder 35 are evenly distributed with three fixed points at 120°, and the inner wall of the flash dryer 3 corresponding to it is provided with three fixed points for cooperation, and is fixed in the form of male and female sleeves. There is an annular gap of 200 mm between the blades of the central cylinder 35 material breaker 34 . An airflow distribution chamber 33 is provided at the bottom of the flash dryer 3, and the bottom surface of the airflow distribution chamber 33 is conical. The height of the hot air inlet apex 32 on the conical bottom surface of the air distribution chamber 33 from the bottom plane 37 of the dryer cylinder is 100 mm. The airflow distribution chamber 33 of the flash dryer 3 has an annular gap height of the hot air inlet increased from 60mm to 100mm. An annular baffle classifier 36 is arranged on the upper surface of the central cylinder 35 in the flash dryer 3 .

The working process of the present invention is as follows:

A. The gas is transported from the pressurizer of the gas station to the hot blast stove 2 through the pipeline. The gas pressure is 7-10KPa. If it is lower than 6KPa, it will automatically alarm. The air enters from the blower 1. The pressure of the combustion air is 6KPa.

B. After the coal gas is burned in the hot blast stove 2, high-temperature gas is produced, and the outlet gas temperature of the hot blast stove is controlled at 350-400°C.

C. The dried aluminum hydroxide is sent into the cylinder body 3 of the flash dryer through the feeding device, and a strong rotating wind field is formed under the rotation of the material breaker 34, and the high-temperature gas flows from the bottom of the dryer along the tangential direction Entering the air distribution chamber 33, the materials are in full contact with the hot air, heated, dried, and collided with each other under strong centrifugal action, rubbed to be micronized, and are in a fluidized state. The dried particles are brought into the upper drying section by the hot air, and continue drying in the cyclone field. There is an annular baffle classifier 36 on the upper part of the flash dryer 3. For those materials with large particles or high water content, when they are thrown to the wall of the dryer due to centrifugal force, they are blocked by the baffle classifier 36. Go back to the drying section and re-dry, and the aluminum hydroxide that has reached the dryness and smaller particle size is taken out from the upper part of the dryer with the hot air. The central cylinder 35 provided in the flash dryer 3 enables the materials to be broken up in the dryer to be rapidly lifted without accumulating. The wind speed in the flash dryer is 5-6m/s, and the outlet pressure is controlled at -1.8～-2.5Kpa. The motor power of the dryer is 30KW.

D. In order to ensure that the moisture after the aluminum hydroxide is dried is less than 0.1%, the aluminum hydroxide comes out from the flash dryer 3 and is then dried by the double swirl dryer 4 and discharged from the top, and enters the cyclone separator 5, and the cyclone separator 5 The exhaust pressure is -4～-7Kpa; the temperature is 90～130℃, the gas discharged from the cyclone separator 5 enters the pulse bag filter 7, and the outlet pressure of the bag filter 7 is -5～-8Kpa, and is discharged by 8 induced draft fans. null.

The pipe diameter in the system is increased from DN300 to DN500, the wind speed is 10-20m/s, and the power of the induced draft fan motor is 75KW.

E. The dried aluminum hydroxide collected by the cyclone separator 5 and the bag filter 7 is collected into the silo 6, and then sent to the next process through the pneumatic conveying pump 9.

Claims (5)

1. aluminium hydroxide dehumidification system, it is characterized in that: it comprises gas blower (1), hotblast stove (2), flash dryer (3), bispin fluidized drying machine (4), cyclonic separator (5), feed bin (6), sack cleaner (7), induced draft fan (8), gas blower (1) links to each other with hotblast stove (2), hotblast stove (2) links to each other with flash dryer (3), flash dryer (3) links to each other with bispin fluidized drying machine (4), bispin fluidized drying machine (4) links to each other with cyclonic separator (5), cyclonic separator (5) links to each other with sack cleaner (7), and sack cleaner (7) links to each other with induced draft fan (8).

2. aluminium hydroxide dehumidification system according to claim 1 is characterized in that: described flash dryer (3) inner bottom part axle (31) is provided with material beater (34), and flash dryer (3) inside is provided with central tube (35).

3. aluminium hydroxide dehumidification system according to claim 2 is characterized in that: described flash dryer (3) bottom is provided with gas distribution chamber (33), and the bottom surface of gas distribution chamber (33) is taper.

4. according to claim 2 or 3 described aluminium hydroxide dehumidification systems, it is characterized in that: described gas distribution chamber (33) hot blast import summit, taper bottom surface (32) is 100mm apart from the height of drying machine cylindrical shell baseplane (37).

5. aluminium hydroxide dehumidification system according to claim 4 is characterized in that: be provided with circular baffle plate classifier (36) above the central tube (35) in the described flash dryer (3).

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