CN103028343A - Production method for pelletoidal calcium chloride dihydrate - Google Patents

Abstract

The invention discloses a production method of spherical calcium chloride dihydrate, which comprises the following steps: entering a 65% to 72% aqueous solution of calcium chloride into a multi-granulation unit fluidized bed granulator through an atomizing nozzle; Enter the fluidized bed granulator; after the atomized gas is heated, it enters the fluidized bed granulator through the atomizing nozzle and atomizes the calcium chloride aqueous solution to the surface of the seed crystal particles; the fluidized gas is heated and passed into the fluidized In the bed granulator, the calcium chloride aqueous solution coated on the surface of the seed crystal particles after atomization is quickly dried and crystallized; when the particles pass through multiple granulation units in sequence, the particle size continues to grow, and the fluidized bed discharge port continuously Discharging; the present invention uses high-concentration calcium chloride solution, and the amount of dehydration in the fluidized bed granulator is small, and the temperature of the fluidized gas used is low, so that the production intensity per unit area of the fluidized bed is large. The lower atomizing gas velocity and the lower penetrating power of the fog torch allow the use of a lower fluidized bed layer, which reduces the resistance of the fluidized gas bed layer and greatly reduces energy consumption, power consumption, and device investment.

Description

A kind of production method of spherical calcium chloride dihydrate

technical field

The invention relates to a production method of inorganic salt calcium chloride, in particular to a production method of spherical calcium chloride dihydrate using a fluidized bed granulation process.

Background technique

There are two types of calcium chloride products: calcium chloride dihydrate and calcium chloride anhydrous, and four types of product appearance: sheet, pellet, block and powder. Among them, spherical calcium chloride products have the advantages of beautiful appearance, good fluidity, no dust, no caking, and no moisture absorption, etc., and are expected to become the mainstream variety of calcium chloride products. Due to the high production cost of the existing spherical calcium chloride production technology, the product price of spherical calcium chloride dihydrate is 50% to 120% higher than that of flake calcium chloride dihydrate. More than 90% of calcium products are still flakes.

Contents of the invention

The purpose of the present invention is to overcome the deficiency that the cost of producing spherical calcium chloride existing in the prior art is too high, and a kind of production method of spherical calcium chloride dihydrate is provided.

Technical scheme of the present invention is summarized as follows:

A production method of spherical calcium chloride dihydrate, comprising the steps of:

The calcium chloride aqueous solution obtained by evaporation with a mass concentration of 65% to 72% is transported by pump, and enters the multi-granulation unit fluidized bed granulator through the atomizing nozzle;

The seed particles enter the multi-granulation unit fluidized bed granulator continuously from the seed silo; the atomized gas supplied by the Roots blower is heated to 170-210°C by the first heat exchanger and then passed through the atomizing nozzle Entering the multi-granulation unit fluidized bed granulator and spraying the calcium chloride aqueous solution onto the surface of the seed crystal particles;

The fluidizing gas supplied by the blower is heated to 110°C-150°C by the second heat exchanger, and then passed into the fluidized bed granulator of the multi-granulation unit through the fluidizing gas inlet, so that it can be sprayed on the The calcium chloride aqueous solution on the surface of the seed crystal particles is rapidly dried and crystallized; the particle size continues to grow when the particles pass through multiple granulation units in sequence, and is continuously discharged from the outlet of the fluidized bed; the discharge of particles from the outlet of the fluidized bed is controlled to Ensure that the height of the particle bed in the multi-granulation unit fluidized bed granulator is 300-700mm; the particles discharged from the fluidized bed outlet are sent to the screening machine through the first bucket elevator, and are screened by the second stage. The particles larger than the qualified particle size are crushed by the crusher, together with the particles smaller than the qualified particle size and a part of the qualified particle size, they are sent to the crystal seed bin through the second bucket elevator as crystal seeds; the other part of the qualified particle size balls The granular calcium chloride dihydrate particles are cooled by the drum cooler and sent to the product silo, and the tail gas of the fluidized bed passes through the washing tower for water washing and dust removal, and then is emptied.

The multi-granulation unit fluidized bed granulator includes a shell, a gas distribution plate and an atomizing nozzle; the gas distribution plate arranged in the lower part of the shell divides the shell into an upper bed and a lower air chamber. The side wall of the chamber is provided with a fluidization gas inlet; the top of the bed is provided with an air outlet, the lower part of the bed side wall is provided with a seed crystal inlet, and the bottom of the bed side wall opposite to the seed crystal inlet is provided with a fluidized bed Outlet; several rows of atomizing nozzles are arranged on the rectangular gas distribution plate, and the atomizing nozzles between each row of atomizing nozzles are misplaced. The annular area around each atomizing nozzle is the spraying area, and the surrounding area It is a fluidized area with a rectangular exterior. Each atomizing nozzle, spray area and fluidization area form a granulation unit. The area of each granulation unit is 0.07-0.15m ² . It is 1/6~1/2 of the fluidization zone; the gas distribution plate adopts a porous plate, and the opening ratio of the gas distribution plate in the spouting zone and the fluidization zone is different, so that the superficial flow velocity of the gas in the spouting zone is the fluidization zone 2 to 4 times; the small holes in the spouting area and the gas distribution plate are vertically arranged; the small holes in the fluidization area and the gas distribution plate are set at an angle of 60-80° and the direction points to the direction of the fluidized bed outlet; the atomization The nozzle includes an annular gas nozzle, and a liquid nozzle with a spiral channel is arranged inside the gas nozzle.

The mass concentration of the calcium chloride aqueous solution entering the fluidized bed granulator of the multi-granulation unit is 65% to 72%, and the temperature is 166°C to 172°C.

The pressure of the atomized gas entering the multi-granulation unit fluidized bed granulator is 20-60kPa, and the temperature is 170-210°C.

Advantages of the present invention:

The mass concentration of the liquid feed calcium chloride aqueous solution of the present invention is 65% to 72%, and the dehydration amount in the multi-granulation unit fluidized bed granulator is small, and the temperature of the fluidized gas is low, so that the fluidized bed unit area High production intensity. The invention adopts relatively low gas velocity of atomized gas, low penetrating force of mist torch, can use relatively low bed height of fluidized bed, and reduces resistance of fluidized gas bed layer. The lower pressure of fluidizing gas and atomizing gas greatly reduces the fan power of fluidizing gas and atomizing gas. Compared with the existing production technology, the method of the present invention greatly reduces energy consumption, power consumption and device investment, and the production cost of the product is equivalent to that of the existing flaky calcium chloride dihydrate.

The fluidized bed of the multi-granulation unit fluidized bed granulator of the present invention is composed of a plurality of granulation units, and the production capacity of the device can be expanded by increasing the number of granulation units. Therefore, the method of the present invention has little risk of amplification and is suitable for large-scale industrial production.

Description of drawings

Fig. 1 is a flow chart;

Fig. 2 is a schematic diagram of a fluidized bed granulator with multiple granulation units;

Fig. 3 is a schematic diagram of a distribution plate of a fluidized bed with 15 granulation units, in which the area occupied by each granulation unit is indicated by a dotted line.

Detailed ways

The present invention will be further described below through specific embodiments and accompanying drawings.

Example 1

A production method of spherical calcium chloride dihydrate, comprising the steps of:

The calcium chloride aqueous solution obtained by evaporation with a mass concentration of 70-71% and a temperature of 169°C-172°C is transported by a pump, and enters the multi-granulation unit fluidized bed granulator through the atomizing nozzle, while controlling the chloride The pressure after the calcium aqueous solution feeding pump pump is 0.26MPa; the seed crystal particles are continuously entered into the multi-granulation unit fluidized bed granulator from the seed crystal silo, and the ratio of the amount of returned material of the control seed crystal to the product output is 1.5:1 ; The atomized gas supplied by the Roots blower is heated to 190°C-210°C by the first heat exchanger, and then enters the multi-granulation unit fluidized bed granulator through the atomization nozzle and atomizes the calcium chloride aqueous solution Apply to the surface of seed crystal particles, and control the atomizing gas pressure at 55-60kPa; the fluidizing gas supplied by the blower is heated to 110-120°C by the second heat exchanger, and then enters the multi-granulation unit through the fluidizing gas inlet In the fluidized bed granulator, the velocity of the fluidized gas in the fluidized bed is controlled to be 1.7-1.9m/s, and the calcium chloride aqueous solution coated on the surface of the seed crystal particles after atomization dries and crystallizes rapidly; the particles pass through multiple During the granulation unit, the particle size continues to grow, and it is continuously discharged from the fluidized bed outlet; the discharge of particles from the fluidized bed outlet is controlled to ensure that the particle bed height in the fluidized bed granulator of the multi-granulation unit is At this time, the bed pressure drop is 3.5kPa; the particles discharged from the outlet of the fluidized bed are sent to the screening machine through the first bucket elevator, and after secondary screening, the particles larger than the qualified particle size are crushed by the crusher Finally, together with particles smaller than the qualified particle size and a part of the qualified particle size, they are sent to the seed bin through the second bucket elevator as crystal seeds; the other part of the qualified spherical calcium chloride dihydrate particles are cooled by the drum After cooling, it is sent to the product silo, and the tail gas of the fluidized bed passes through the washing tower to wash and remove dust, and then it is emptied. After the operation is stable, the bed temperature of the fluidized bed is about 90-100°C, the calcium chloride content of the product is 74%-75%, and the output of each nozzle is about 300-330kg/h. (see picture 1)

The multi-granulation unit fluidized bed granulator includes a shell, a gas distribution plate 1 and an atomizing nozzle 10; the gas distribution plate 1 arranged in the lower part of the shell divides the shell into an upper bed body 2 and a The air chamber 3 in the lower part is provided with a fluidizing gas inlet 6 on the side wall of the air chamber; the top of the bed is provided with an air outlet 9, and the lower part of the side wall of the bed is provided with a seed crystal inlet 4, and the bed opposite to the seed crystal inlet The bottom of the side wall of the body is provided with a fluidized bed outlet 5; a number of rows of atomizing nozzles 10 are arranged on the rectangular gas distribution plate, and the atomizing nozzles between each row of atomizing nozzles are misplaced, and around each atomizing nozzle The annular area is the spray area 11, and the periphery of the spray area is a rectangular fluidized area 12. Each atomizing nozzle, spray area and fluidized area form a granulation unit, and the area of each granulation unit is 0.07 m ² -0.10m ² , in which, the area occupied by the eruption zone is 1/3-1/2 of the fluidization zone; The apparent flow velocity is three times that of the fluidized zone; the small holes in the spouting zone are arranged vertically to the gas distribution plate; the small holes in the fluidized zone are set at an angle of 70° to the gas distribution plate and the direction points to the outlet of the fluidized bed; The atomizing nozzle includes an annular gas nozzle 13, and a liquid nozzle 14 with a spiral channel is arranged inside the gas nozzle. (See Figure 2 and Figure 3)

Example 2

A production method of spherical calcium chloride dihydrate, comprising the steps of:

The calcium chloride aqueous solution obtained by evaporation with a mass concentration of 65-67% and a temperature of 166°C-168°C is transported by a pump, and enters the multi-granulation unit fluidized bed granulator through the atomizing nozzle, and the calcium chloride solution is controlled at the same time. The pressure after the aqueous solution feeding pump is 0.27MPa, and the seed crystal particles are continuously entered into the multi-granulation unit fluidized bed granulator from the seed crystal silo, and the ratio of the amount of returned material of the seed crystal to the product output is controlled to be 0.5:1; The atomized gas supplied by the Roots blower is heated to 170-180°C by the first heat exchanger, and then enters the multi-granulation unit fluidized bed granulator through the atomization nozzle, and the calcium chloride aqueous solution is atomized and coated To the surface of seed crystal particles, control the pressure of the atomizing gas to 20-30kPa; the fluidizing gas supplied by the blower is heated to 145°C-150°C by the second heat exchanger, and then passes through the inlet of the fluidizing gas into the flow of the multi-granulation unit. In the fluidized bed granulator, the velocity of the fluidized gas in the fluidized bed is controlled to be 2.7-3m/s; the calcium chloride aqueous solution coated on the surface of the seed crystal particles after atomization dries and crystallizes rapidly; The particle size grows continuously during the unit, and is continuously discharged from the outlet of the fluidized bed; the discharge of particles from the outlet of the fluidized bed is controlled to ensure that the particle bed height in the fluidized bed granulator of the multi-granulation unit is 300mm , the bed pressure drop is 3kPa at this time; the particles discharged from the outlet of the fluidized bed are sent to the screening machine through the first bucket elevator, and after secondary screening, the particles larger than the qualified particle size are crushed with the crusher Particles smaller than the qualified particle size and a part of the qualified particle size are sent to the seed bin through the second bucket elevator to be used as crystal seeds; the other part of the qualified particle size spherical calcium chloride dihydrate particles is cooled by the drum cooler Afterwards, it is sent to the product silo, and the tail gas of the fluidized bed passes through the washing tower for water washing and dust removal, and then is emptied. After stable operation, the bed temperature of the fluidized bed is about 120-130°C, the calcium chloride content of the product is 82%-84%, and the output of each nozzle is about 350-380kg/h.

The multi-granulation unit fluidized bed granulator includes a shell, a gas distribution plate 1 and an atomizing nozzle 10; the gas distribution plate 1 arranged in the lower part of the shell divides the shell into an upper bed body 2 and a The air chamber 3 in the lower part is provided with a fluidizing gas inlet 6 on the side wall of the air chamber; the top of the bed is provided with an air outlet 9, and the lower part of the side wall of the bed is provided with a seed crystal inlet 4, and the bed opposite to the seed crystal inlet The bottom of the side wall of the body is provided with a fluidized bed outlet 5; a number of rows of atomizing nozzles 10 are arranged on the rectangular gas distribution plate, and the atomizing nozzles between each row of atomizing nozzles are misplaced, and around each atomizing nozzle The annular area is the spray area 11, and the periphery of the spray area is a rectangular fluidized area 12. Each atomizing nozzle, spray area and fluidized area form a granulation unit, and the area of each granulation unit is 0.10 m ² -0.13m ² , in which, the area occupied by the eruption zone is 1/4-1/6 of the fluidization zone; The apparent flow velocity is 4 times that of the fluidized zone; the small holes in the spouting zone are arranged vertically to the gas distribution plate; the small holes in the fluidized zone and the gas distribution plate are set at an angle of 60° and the direction points to the direction of the outlet of the fluidized bed; The atomizing nozzle includes an annular gas nozzle 13, and a liquid nozzle 14 with a spiral channel is arranged inside the gas nozzle.

Example 3

A production method of spherical calcium chloride dihydrate, comprising the steps of:

The calcium chloride aqueous solution obtained by evaporation with a mass concentration of 72% and a temperature of 169 ° C to 172 ° C is transported by a pump, and enters the multi-granulation unit fluidized bed granulator through the atomizing nozzle, and the calcium chloride aqueous solution feeding pump is controlled at the same time The pressure behind the pump is 0.4MPa, and the seed crystal particles are continuously entered into the multi-granulation unit fluidized bed granulator from the seed crystal silo, and the ratio of the amount of returned seed crystals to the product output is controlled to be 1:1; The atomized gas supplied by the blower is heated to 190-200°C by the first heat exchanger, and then enters the multi-granulation unit fluidized bed granulator through the atomization nozzle, and the calcium chloride aqueous solution is atomized and coated on the seed crystal On the particle surface, the atomizing gas pressure is controlled at 40-50kPa; the fluidizing gas supplied by the blower is heated to 120°C-130°C by the second heat exchanger, and then passed into the multi-granulation unit fluidized bed through the inlet of the fluidizing gas. In the granulator, the velocity of the fluidized gas in the fluidized bed is controlled to be 2.3-2.5m/s. After atomization, the calcium chloride aqueous solution coated on the surface of the seed crystal particles dries and crystallizes rapidly; the particle size continues to grow when the particles pass through multiple granulation units in sequence, and is continuously discharged from the outlet of the fluidized bed; the outlet of the fluidized bed is controlled The discharge rate of the particles at the feed port is to ensure that the height of the particle bed in the fluidized bed granulator of the multi-granulation unit is 700mm, and the pressure drop of the bed is 6kPa at this time; the particles discharged from the fluidized bed outlet pass through the first The bucket elevator is sent to the screening machine, and after secondary screening, the particles larger than the qualified particle size are crushed by the crusher, and then sent to the crystal through the second bucket elevator together with the particles smaller than the qualified particle size and a part of the qualified particle size. The seed silo is used as the crystal seed; the other part of spherical calcium chloride dihydrate particles with qualified particle size is cooled by the drum cooler and then sent to the product silo, and the tail gas of the fluidized bed is washed and dusted by the scrubber and then emptied. After stable operation, the bed temperature of the fluidized bed is about 110-120°C, and the calcium chloride content of the product is 78%-80%. The output of each nozzle is about 570~600kg/h.

The multi-granulation unit fluidized bed granulator includes a shell, a gas distribution plate 1 and an atomizing nozzle 10; the gas distribution plate 1 arranged in the lower part of the shell divides the shell into an upper bed body 2 and a The air chamber 3 in the lower part is provided with a fluidizing gas inlet 6 on the side wall of the air chamber; the top of the bed is provided with an air outlet 9, and the lower part of the side wall of the bed is provided with a seed crystal inlet 4, and the bed opposite to the seed crystal inlet The bottom of the side wall of the body is provided with a fluidized bed outlet 5; a number of rows of atomizing nozzles 10 are arranged on the rectangular gas distribution plate, and the atomizing nozzles between each row of atomizing nozzles are misplaced, and around each atomizing nozzle The annular area is the spray area 11, and the periphery of the spray area is a rectangular fluidized area 12. Each atomizing nozzle, spray area and fluidized area form a granulation unit, and the area of each granulation unit is 0.11 m ² -0.15m ² , in which, the area occupied by the eruption zone is 1/4-1/6 of the fluidization zone; The apparent flow velocity is twice that of the fluidized zone; the small holes in the spouting zone are arranged perpendicular to the gas distribution plate; the small holes in the fluidized zone are set at an angle of 80° to the gas distribution plate and the direction points to the direction of the outlet of the fluidized bed; The atomizing nozzle includes an annular gas nozzle 13, and a liquid nozzle 14 with a spiral channel is arranged inside the gas nozzle.

Claims (4)

1. a production method of spherical calcium chloride dihydrate is characterized in that it may further comprise the steps: The calcium chloride aqueous solution obtained by evaporation with a mass concentration of 65% to 72% is transported by pump, and enters the multi-granulation unit fluidized bed granulator through the atomizing nozzle; The seed particles enter the multi-granulation unit fluidized bed granulator continuously from the seed silo; the atomized gas supplied by the Roots blower is heated to 170-210°C by the first heat exchanger and then passed through the atomizing nozzle Entering the multi-granulation unit fluidized bed granulator and spraying the calcium chloride aqueous solution onto the surface of the seed crystal particles; The fluidizing gas supplied by the blower is heated to 110°C-150°C by the second heat exchanger, and then passed into the fluidized bed granulator of the multi-granulation unit through the fluidizing gas inlet, so that it can be sprayed on the The calcium chloride aqueous solution on the surface of the seed crystal particles is rapidly dried and crystallized; the particle size continues to grow when the particles pass through multiple granulation units in sequence, and is continuously discharged from the outlet of the fluidized bed; the discharge of particles from the outlet of the fluidized bed is controlled to Ensure that the height of the particle bed in the multi-granulation unit fluidized bed granulator is 300-700mm; the particles discharged from the fluidized bed outlet are sent to the screening machine through the first bucket elevator, and are screened by the second stage. The particles larger than the qualified particle size are crushed by the crusher, together with the particles smaller than the qualified particle size and a part of the qualified particle size, they are sent to the crystal seed bin through the second bucket elevator as crystal seeds; the other part of the qualified particle size balls The granular calcium chloride dihydrate particles are cooled by the drum cooler and sent to the product silo, and the tail gas of the fluidized bed passes through the washing tower for water washing and dust removal, and then is emptied. 2. The method according to claim 1, wherein the multi-granulation unit fluidized bed granulator comprises a housing, a gas distribution plate and an atomizing nozzle; the gas distribution plate arranged in the lower part of the housing The shell is divided into an upper bed body and a lower air chamber, the side wall of the air chamber is provided with a fluidization gas inlet; the top of the bed body is provided with an air outlet, and the lower part of the bed side wall is provided with a seed crystal inlet, which The bottom of the side wall of the bed opposite to the seed crystal inlet is provided with a fluidized bed discharge port; several rows of atomizing nozzles are arranged on the rectangular gas distribution plate, and the atomizing nozzles between each row of atomizing nozzles are misplaced. The annular area around the atomizing nozzle is the spraying area, and the surrounding of the spraying area is a rectangular fluidized area. Each atomizing nozzle, spraying area and fluidized area form a granulation unit. The area of each granulation unit is It is 0.07～0.15m ² , of which, the area occupied by the spouting zone is 1/6～1/2 of the fluidization zone; the gas distribution plate adopts a perforated plate, and the gas distribution plate in the spouting zone and the fluidization zone has holes The gas superficial velocity in the spouting zone is 2 to 4 times that of the fluidization zone; the small holes in the spouting zone are vertical to the gas distribution plate; the small holes in the fluidization zone and the gas distribution plate are at an angle of 60 to 80° It is set and the direction is directed to the outlet of the fluidized bed; the atomizing nozzle includes an annular gas nozzle, and a liquid nozzle with a spiral channel is arranged inside the gas nozzle. 3. The method according to claim 1, characterized in that the calcium chloride aqueous solution entering the multi-granulation unit fluidized bed granulator has a mass concentration of 65% to 72%, and a temperature of 166°C to 172°C. 4. The method according to claim 1, characterized in that the pressure of the atomized gas entering the multi-granulation unit fluidized bed granulator is 20-60kPa, and the temperature is 170-210°C.

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