RU2544698C2 - Device for rectification distillation of liquid fraction mixture in carrier flow - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: device contains the distillation still with pre-heater, column divided through height by the horizontal partitions. Lines for separate supply of the input feed and carrier are equipped with heaters. Device contains carrier recycling line, product fractions condensation unit in form of the nozzle type fractional column and product fractions outlet branch pipes. In the distilling still the bubbler is installed. The column partitions are partially perforated, and between perforation zones without clearance the pore nozzle blocks are installed. The product fractions outlet branch pipes are installed on the column above planes of the appropriate horizontal partitions. Inlet branch pipe of the feed supply line is installed below the product fractions outlet branch pipes. The device can include feed recycle line from the distilling still connecting to the feed supply line. The bubbler is made in form of the gas-liquid riser with internal circulation. In the distilling still the pore gas-permeable heater is installed above the liquid phase surface of the distillable product.

EFFECT: increased productivity, reduced size and weight characteristics.

4 cl, 2 dwg, 1 ex

Description

The device relates to the field of technologies for cleaning liquid mixed raw materials during heat and mass transfer processes in order to separate it into components and can be used in the chemical, oil refining, petrochemical industries, in particular, to obtain high-purity aluminum isopropylate. High-purity metal alkoxides, including aluminum isopropylate, are used, for example, for the production of laser ceramics.

A device for the distillation of triisobutylaluminum is known (copyright certificate No. 131351, IPC C07F 5/06, publ. "Bulletin of the invention" No. 17 for 1960). Distillation is carried out in a carrier stream (isobutylene) at atmospheric or elevated pressure in a closed distillation system at a column temperature of 50 ° C. The device consists of a distillation cube, a distillation column equipped with nozzles with a developed surface, collections of product fractions. These method and device can improve product quality.

The disadvantage of this device is the fractional-continuous process of supplying a raw material product, which increases the distillation time and reduces the productivity of the process.

A device for the distillation of glycerol in an inert gas stream (copyright certificate No. 40346, IPC С07С 31/22, publ. 12/31/1934). Distillation is carried out at normal pressure at a temperature above 180 ° C in a carrier stream. The cycle of motion of the carrier (inert gas) is closed. Nitrogen was taken as an inert gas. The device is equipped with a distillation cube, equipped with a bubbler for supplying carrier gas, alternately connected refrigerators (reflux condensers), gas separators. The result of distillation is to obtain glycerol with a concentration of (95-98)%.

The disadvantages of this device are:

- the lack of recycling sparged raw materials, which leads to a decrease in the purity of the final shared products;

- an increase in the dimensions of the device due to the withdrawal of product fractions together with the carrier and their further separation.

A device for rectification is known (patent RU No. 2069070, publication date 11/20/1996, IPC B01D 3/32). The device contains a distillation cube with a container for collecting bottoms, a tank located in the cube with a gap in the upper part and interconnected in pairs and liquids, bubblers for supplying gas or steam to removable filter baffles, a distillation column for condensing the spent steam and withdrawing it in atmosphere. The device is intended for cleaning liquid coolants of nuclear power plants, which improves the purity of the coolant by removing mechanical particles, including sulfur compounds.

The disadvantages of this device are:

- the absence of a closed cycle of the use of carrier gas, which leads to an increase in costs, as a result of which the cost of the final product increases;

- cumbersome complex construction of the distillation cube.

A device is known that is closest to the claimed device for its intended purpose, technical essence and the achieved effect for distillation of the raw liquid fractional mixture in the carrier stream (patent RU No. 2343948, publication date 11/14/2006, IPC B01D 3/00). Distillation is carried out in water vapor entering the cube in the form of an aqueous emulsion of raw materials. A device for distillation distillation of liquid raw materials in a carrier stream consists of a distillation cube with a heater, a pipe for removing distillation residue and a column divided by horizontal partitions in height. Separate feed lines of feedstock and carrier are equipped with heaters. The device comprises a carrier recycling line, condensation units for product fractions, and nozzles for selecting product fractions. The horizontal partitions are equipped with vertical plates and are made in the form of zigzag corridors. Horizontal partitions are interconnected using external overflow pipes. The separation of product fractions and the carrier occurs in separate heat exchangers with water locks located outside the distillation column. The device is intended to increase the efficiency of the process of separation of the initial raw liquid fractional mixture.

This device is selected as a prototype of the proposed device.

The disadvantages of this device are:

- limited ability to distill raw materials that interact with water, as water is used as a carrier;

- high overall-mass characteristics of the structure as a whole, associated with the process of separating the mixed component and carrier vapor outside the distillation column;

- relatively high energy costs per unit mass of the purified final product, associated with the continuous expenditure of heat on the conversion of the return liquid carrier (water) to steam.

The objective of the invention is to reduce the overall mass characteristics of the device while maintaining the efficiency of distillation of the feedstock and at the same time reducing energy costs per unit of the final product.

When using the present invention, the following technical result is achieved:

- increase in productivity by an average of 15%;

- overall mass characteristics of the device are reduced, about four times in comparison with the prototype;

- when cleaning aluminum isopropylate, the amount of impurities does not exceed 5 ppm for 28 elements;

- the unit cost of production of aluminum isopropylate is reduced by 1.5 times while maintaining its high purity.

To solve this problem and achieve a technical result in a device for distillation distillation of a liquid fractional mixture in a carrier stream containing a distillation cube with a heater, a pipe for removal of distillation residue, a column divided in height by horizontal partitions, separate feed lines for the feedstock and carrier, equipped with heaters , a carrier recycling line, a condensation unit of product fractions and nozzles for their selection, according to the invention, a bubbler is installed in the distillation cube, horizontal the partition walls of the column are partially perforated, and porous nozzle blocks are seamlessly installed between their perforation zones, product fractions are installed on the column above the planes of the corresponding horizontal partitions, the input pipe of the feed input line is installed below the product fractions, and the condensation unit of the product fractions is made in the form nozzle type reflux condenser.

Moreover, it is admissible that:

- the device contains a line for recycling raw materials from a distillation cube, which is closed to a feed line for raw materials;

- the bubbler is made in the form of a gas-liquid elevator with internal circulation;

- in the distillation cube a porous gas-permeable heater is installed, located above the plane of the initial raw liquid fractional mixture.

The presence in the device for distillation distillation cube with a heater and a branch pipe for the removal of bottoms provides such a technical effect as the ability to place a metered amount of liquid raw materials intended for distillation, maintaining the required process temperature and continuous removal of bottoms.

The distillation column, divided in height by horizontal partitions, allows you to separate multicomponent mixtures into fractions having different condensation temperatures. The presence of separate feed lines for the feedstock and the carrier allows them to be mixed in a distillation cube in order to realize the effect of an airlift in it.

The presence of heaters on the lines of raw materials and media provides the ability to maintain their required nominal temperatures. The carrier is returned to the technological process through its recycling line, which ensures a reduction in the cost of the technological process as a whole.

The installation of a condensation unit on the distillation column made in the form of a packed-type reflux condenser allows returning to the distillation column all condensed fractions. This provides such a technical effect as the fundamental possibility of separating all condensing fractions from the carrier, in particular, inert gas, which ensures a decrease in the overall mass characteristics of the device as a whole.

The installation of sampling pipes directly on the column also provides a significant reduction in the overall mass characteristics of the installation as a whole (in the proposed installation, the condensation of the respective fractions is implemented directly in the column, unlike the prototype).

The installation of a bubbler type of a gas-liquid elevator with internal circulation in the distillation cube makes it possible in principle to realize such a technical effect as an airlift of a pair of separated mixed fractions with temperature control of the gas-liquid fractional mixture due to its heating at the return current along the heated wall of the distillation cube. At the same time, such an airlift provides an increase in the contact surface of the carrier gas with the feedstock and ensures the transfer of the vapor mixture fractions of the distilled liquid into the distillation column with the required increase in productivity.

The horizontal partitions of the column are partially perforated and the installation of porous packed blocks between them makes it possible to ensure the corresponding heat and mass transfer process, which leads to the separation of condensable product fractions with a high degree of purity of the obtained product.

The installation of branch pipes for selecting product fractions in a column above the planes of the corresponding product fractions makes it possible to control both the height of their horizontal layer and the discharge of that product fraction that corresponds to its condensation temperature.

The inlet branch pipe of the feed line is installed below the branch pipes for selecting product fractions, which allows to increase the productivity of the process and the purity of the separated fractions due to the intensification of mass and heat transfer between the falling liquid stream and superheated vapors of the separated components.

The introduction of the recycling line of the raw material from the distillation cube, which is closed to the feed line of the feedstock, provides a deeper degree of separation of the distilled feedstock due to additional intensification of mass and heat transfer of the incoming phases in the distillation column.

The presence of a porous gas-permeable heater located inside the distillation cube above the plane of the liquid phase provides such a technical effect as additional heating of the vapor-nitrogen mixture, which, in some cases, ensures the thermodynamic stability of vapor fractions, eliminating their release in the form of solid aerosol agglomerates.

The set of essential features of the claimed invention allows to achieve a degree of purification of the feedstock to a level of not less than 99.9999%, while reducing the overall mass characteristics of the device as a whole and at the same time reducing energy costs per unit mass of the final product.

For the practical implementation of distillation distillation of a raw liquid fractional mixture in a carrier stream, the apparatus shown in FIG. 1 is proposed. Figure 2 shows the inner part of the distillation column with a drain pipe.

The inventive device consists of a distillation cube 1, a distillation column 2, a source of feedstock 3 and a source of carrier gas 4. The distillation cube is equipped with a heater 5 mounted on its outer surface and a pipe 6 for removal of distillation residue. In the distillation cube 1 there is a bubbler 7 and a porous gas-permeable heater 8 installed in the upper part of the cube 1.

The distillation column 2 is divided in height by horizontal partitions 9, the surface of which is partially perforated (FIG. 2), and porous packed blocks 11 are installed between the perforated parts 10. On the column 2 there is a pipe 12 for selecting a heavy product fraction, a pipe 13 for selecting light fractions and a pipe 14 for outputting the carrier gas. The nozzles 12 and 13 are installed above the planes of the corresponding horizontal partitions 9. On the horizontal partitions 9, the height of the layer A (Fig. 2) of the product fractions is maintained above sections B of the nozzles 12 and 13. On top of the column 2 there is a condensation unit 15, made in the form of a nozzle type reflux condenser cooled by water.

The feed line includes a source of feed 3, connected through a metering pump 16 and a heater 17 to the pipe 18 of the distillation column 2, in which the spray nozzle 19 is installed. A pipe 18 (input of the feed line) is installed on the column 2 below the pipes 12, 13 selection of food fractions.

The device comprises a recycle line of carrier gas exiting the nozzle 14, and a recycle line of raw materials from the distillation cube 1, connected through the nozzle 20 and the metering pump 21 to the feed line.

The carrier gas supply line from source 4 to the bubbler 7 comprises a metering pump 22 and a heater 23.

The device operates as follows.

In the distillation cube 1, equipped with a bubbler 7, a heater 5 and a porous gas-permeable heater 8, a raw fractional liquid mixture, for example, metal alcoholate, heated to a working temperature of (120-170) ° C by a heater 17 through an inlet pipe 18, is continuously fed through a metering pump 16 and a spray nozzle 19. At the same time, an inert carrier gas heated to the temperature of the raw material mixture is supplied from the source 4 to the bubbler 7 through a heater 7 through a heater 23. Due to the effect of the air lift, a standing gas-liquid vortex is realized in the distillation cube 1, from which the heavier fractions condense under the bubbler plane. In this case, the temperature of the gas-liquid mixture, at its return current along the heated wall of the distillation cube, is maintained at the temperature of the raw material mixture.

The mixture of feed alcoholate and carrier gas recycled from the distillation cube 1 through the branch pipe 20 is continuously returned to the cycle by means of the metering pump 21 together with the newly supplied metal alcoholate feedstock from the source 3 through the pipe 18 and the atomizing nozzle 19. The vapor of the fractional mixture and carrier gas in the cube 1 additionally heated, passing through a porous gas-permeable heater 8, and rush up into the distillation column 2 with horizontal partitions 9.

Column 2 maintains a certain temperature gradient in order to condense the corresponding fractions on the corresponding partitions. Metal alcoholate is discharged on the lower partition 9, and increasingly lighter fractions on the upper. The heavy fractions merge through the pipe 6 removal of bottoms. Pure metal alcoholate settles on the horizontal partition 9, accumulates on it to the calculated height and merges through the outlet pipe 12.

All light product fractions with a speed that maintains the calculated height on the partition 9 are condensed by a condensation unit made in the form of a reflux condenser 15 and merged from the upper horizontal partition 9 through the nozzle 13. The carrier gas free from condensing vapors is discharged through the nozzle 14 and returns into the cycle together with the newly arriving carrier gas, the amount of which compensates for its technological losses. VAT residue from the distillation cube 1 is continuously discharged through the lower pipe 6 for disposal or processing.

EXAMPLE 1

A dirty raw aluminum isopropylate of aluminum is continuously fed into the distillation cube at a speed of 40 l / h with a temperature of 120 ° C from the source of the feedstock. At the same time, nitrogen (carrier gas) is supplied to the bubbler at a speed of 36 m ³ / h. Vapors of the fractional mixture, including aluminum isopropylate vapor, enter the column in a stream of nitrogen. The cleaned aluminum isopropylate is discharged from the lower product partition with a volumetric velocity of 36 l / h at a temperature of (117.5 ± 0.25) ° C on it. Lighter fractions (isopropyl alcohol and other alcoholates that make up the light fractions) are discharged from the horizontal partition of the light fractions, with a bulk velocity of 3.2 l / h, at a temperature of 95 ° C. Nitrogen, freed from transported substances, passes through a reflux condenser, is cleaned of mechanical particles and trapped drops of isopropylate, and returns to the technological cycle. The bottom residue, consisting of heavy fractions, continuously merges with the stream at a speed of 0.8 l / h. The installation provides an increase in productivity by an average of 15%, while reducing the unit cost of the final product by 1.5 times. The amount of impurities in the purified aluminum isopropylate does not exceed 5 ppm for 28 elements.

Claims (4)

1. A device for the distillation distillation of a liquid fractional mixture in a carrier stream, including a distillation cube with a heater, a pipe for removing distillation residue, a column divided by height by horizontal partitions, separate feed lines for feedstock and carrier, equipped with heaters, a carrier recycling line, a condensation unit product fractions and nozzles for their selection, characterized in that a bubbler is installed in the distillation cube, the horizontal partitions of the column are partially perforated, and perforations between their zones porous packed blocks were installed without any gap, the branch pipes for selecting product fractions were mounted on the column above the planes of the corresponding horizontal partitions, the branch pipe for entering the feed line was installed below the branch pipes for selecting product fractions, and the condensation unit for the product fractions was made in the form of a packed type reflux condenser. 2. The device according to claim 1, characterized in that it contains a line for recycling raw materials from a distillation cube, which is closed to the supply line of the initial raw liquid fractional mixture. 3. The device according to claim 1 or 2, characterized in that the bubbler is made in the form of a gas-liquid elevator with internal circulation. 4. The device according to claim 1, characterized in that a porous gas-permeable heater located above the plane of the initial liquid fractional mixture is installed in the distillation cube.

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