SU1549580A1 - Reactor for obtaining extraction phosphoric acid - Google Patents

Abstract

The invention relates to the design of reactors for the production of phosphoric acid and allows for an increase in productivity and a reduction in specific energy consumption. The reactor includes a housing, a cylindrical loading section and peripheral sections of circulation and unloading, divided by partitions with cylindrical walls with axial mixers located in them, a submerged-type vacuum evaporator, inlet pipes for starting components, reaction gases and a nozzle for discharging pulp with overflow, with the housing vacuum - the evaporator is located coaxially above the loading section, while its lower section forms a gap with a transverse partition and the loading section, the area ratio of which is 0 , 9-1.2, and the central loading section is installed with a gap to the bottom of the cylindrical body, the size of which is 0.5-1.5 of the diameter of the loading section. 4 il.

Description

The invention relates to the design of reactors for heat and mass transfer processes and is intended to produce extraction phosphoric acid.

The aim of the invention is to increase productivity and reduce energy consumption.

FIG. 1 shows schematically a reactor, a general view, a longitudinal section; in fig. 2 - data on energy consumption; in fig. 3 - performance data; in fig. 4 - data on energy consumption.

The reactor contains a vertical cylindrical body 1, the central

cylindrical loading section 2 and peripheral sections of circulation 3 and unloading 4, separated by a transverse partition 5 placed below the pulp level with cylindrical cups 6 installed in it with axial agitators 7, perpendicular to the latter (b), mixing device drives 8 located on the lid 9 housing 1, the vacuum evaporator 10 flooded type, the nozzle input source components 1 1 and removal of the pulp 12 with overflow 13 and the nozzle 14 of the reaction gases.

The reactor operates as follows.

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-and

with

On

00

When the vacuum evaporator is connected to the vacuum system through the nozzle J4, the equality of the pulp levels in the vacuum evaporator 10 and the discharge section 4 is violated.

Axial agitators 7 are turned on. Further, the phosphorus raw material in the form of pulp is fed to the loading section 2 through the input pipe 11 of the initial components, moves down and enters the circulation section 3 through the gap formed by the lower section of the loading section 2 and the bottom of the housing 1. Then the pulp entrained by the flow and fed through the cylindrical glasses 6 by means of axial agitators 7 to the unloading section 4. A part of the pulp through the nozzle 12 of the pulp withdrawal enters the overflow 13, and the main part enters through the vacuum-evaporator 10 again into the loading section 2, thereby circulating the pulp.

This reactor allows reducing the number of fine calcium sulfate crystals, which is achieved by reducing the temperature gradient in the vacuum evaporator and increasing the multiplicity of pulp circulation in the reactor. And an increase in the rate of circulation through the cooling system — the vacuum evaporator is solved by creating high-performance centrifugal displaced mixing devices. The reduction of the temperature gradient was possible due to the high speed of the pulp of the vacuum evaporator — a high rate of circulation of the pulp through the cooling system, which made it possible to introduce sulfuric acid directly into the cooling circuit to ensure optimal concentration conditions, i.e. its good dilution, which gives additional heat and improves the performance of the circulation circuit.

The pulp circulation method, proposed in this reactor design with cooling through a vacuum evaporator with high multiplicity (30-35), makes it possible to fundamentally reconsider the issue of the specific energy consumption for mixing the reaction pulp.

Due to the evaporation of moisture over a reduced vacuum through multiple circulation of the pulp with a minimum temperature gradient & t (2.5-2) C

favorable conditions for the growth of phosphogypsum crystals are created.

As the graph of FIG. 2, within the proposed ratio of 0.5-1.5, the energy consumption for mixing and circulation of the pulp is minimal, which is an economical condition for the operation of the reactor.

When this ratio is increased by more than 1.5, the process of phosphate decomposition by recycled pulp lengthens with time, which leads to the production of gypsum in the form of fine needles.

By reducing this ratio to less than 0.5, the phosphate decomposition process time also lengthens, but does not affect the quality of the calcium sulfate crystals produced, and the energy consumption increases significantly.

As can be seen from the graph of FIG. 3, within the proposed area ratio of 0.9-1.2, the capacity of the extractor is maximum, and this is also the optimal condition for the operation of the reactor.

The proposed reactor design with a ratio of the required parameters allows to significantly increase the productivity of the reactors and at the same time reduce the energy consumption for pulp mixing.

As can be seen from the graph of FIG. 4 the energy consumption in the proposed reactor will be significantly lower than in the prototype reactor of the same capacity by about 2-2.5 times.

To achieve a positive effect, each of the required signs is necessary and sufficient.

Supplying the reactor with a transverse partition with cylindrical cups installed in it with axial agitators perpendicular to the latter allows the pulp to be passed only through mixing devices during its circulation, which causes an improvement in the quality of the final product and the elimination of the unreacted material entering the discharge section for filtration.

Separating the loading section from the bottom of the housing allows changing the direction of the pulp circulation, which significantly reduces energy consumption for pulp mixing.

The choice of the ratio of the gap between the lower cut of the loading section and the bottom of the body 0.5-1.5 allows 12

1

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QOOQ 8 00a 6000 4Ш

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FIG. 2

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0.7 bb 0.9 1.0 1.1 12 l3 S Tt / SzFig. 3

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4000 600O 8000 Iff 000 figL

Compiled by A. Telesnitsky Editor M. Bandura Tehred A. Kravchuk Proofreader O. Kravtsova

2.0

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flpomo / un

9

Claims (1)

Claim Reactor for producing phosphoric acid, comprising a vertical tubular shell, a cylindrical central section and the loading section and peripheral circulation discharging separated transferred · ¹ towns with them arranged in the cylindrical walls with axial impellers vacuum evaporator flooded, nozzle input starting components, discharge of pulp with overflow and reaction gases, characterized in that, in order to increase productivity and reduce specific energy consumption, the housing of the vacuum evaporator ra laid coaxially above the loading section, while its lower slice forms a gap with a transverse partition and the loading section, the area ratio of which is 0.9-1.2, and the central loading section is installed with a gap to the bottom of the cylindrical body, the value of which is 0.5 - 1.5 diameters of the loading section. Π Q, 6 FIG. 2 L [X I, 10000. 8000 & 000 4000 2000 ABOUT 0.7 0.0 0.3 1.0 1.1 1.2 1.3 1.4 Sf / S ₂ ^ 0.3