JPS598401B2 - Rotating film column for bringing gas and liquid into contact - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to apparatus for performing mass transfer processes, and more particularly to a rotating film column for providing contact between a gas (vapour) and a liquid.

The present invention is preferably used in the field of vacuum rectification of substances sensitive to high temperatures, such as lactams, fatty acids, polyhydric alcohols, ethanolamines, high-boiling esters, various oils, foods, and pharmaceuticals.

The presented invention will be used in the chemical industry, petroleum refining, food industry, pharmaceutical industry, etc.

a housing having branch pipes for supplying gas into the lower part of the column, for removing said gas from the upper part of the column, for supplying liquid into the column and for removing liquid from the column; and in the housing; Rotating film columns are known in the art that provide contact between gas and liquid and consist of a vertical shaft mounted for rotation.

(See USSR Inventor's Certificate No. 203621). Several contact stages, located at certain distances from each other, are mounted on the shaft.

The contact stage is formed by a bent band like a flat spiral member extending from the shaft.

The band is flanged on its sides towards the axis.

The rotary film column is also provided with equipment for moving liquid from one contacting stage to another.

These devices include an annular pocket fixed on the inside wall of the housing and used to receive liquid exiting the contact stage; and an overflow tray.

The overflow tray occupies the space between the contact stages. The receiving end of the tray communicates with an annular pocket that collects liquid flowing from the upper tier.

The outlet end of the tray is located above the underlying contact stage.

During operation of a rotary film tower, its shaft rotates.

Gas enters into the lower part of the column and is removed from the upper part of the column through a branch pipe.

The liquid moves downward into the column by gravity from one contacting stage to another.

All the contacting stages of the column rotate together with the axis, so that the liquid on the contacting stages and subjected to centrifugal force flows in a film along the internal surface of the band, ie the surface facing the axis.

Since the sides of the band are flanged towards the axis, the liquid does not drip out of the band, but moves from the center to the periphery of the contact stage along the spiral path.

From around the contact stage, the liquid is dumped onto the wall of the column housing and then flows down by gravity into the annular pocket.

From this pocket liquid flows into the receiving end of the underlying tray whose outlet end is located above the next contact stage.

Liquid flows from the tray onto this stage and its movement is similar to that on the contact stage above.

The liquid discharged from the bottom contacting stage of the column exits through a branch in the lower part of the column.

The upwardly moving gas passes through a contact stage and contacts a film of liquid that wets the inside of the flanged convoluted band.

A disadvantage of known rotating film columns for providing gas-liquid contact is the limited gas-liquid contact surface.

The contact surfaces in the column are limited to the entire working surface of the contact stages.

The working surface of the contact stage is inside the flanged spiral band,
That is, only the side facing the axis and covered with a moving liquid film.

Additionally, the liquid film drenched inside the spiral band is not sufficiently agitated while moving along the spiral path from the center to the periphery of the contact stage.

This is due to the fact that the liquid film rotates with the contacting stage and in this case the energy of the rotation of the contacting stage is not used for additional stirring of the film.

Rotation of the contact stage is provided only to form a liquid film on the wetted surface of the band and to move the film around the device under the influence of centrifugal force.

Limited surface contact between gas and liquid and insufficient agitation of the liquid film during the contact process limit further increases in mass transfer efficiency in known raw film columns.

It is an object of the present invention to provide a gas-liquid contacting raw film column having a developed contact surface and a device for further agitating the liquid film.

This makes it possible to further intensify the mass exchange process in the column.

This objective is achieved by providing a rotating film column for making contact between gas and liquid, which is used to supply gas into the bottom of the housing and to withdraw gas from the top of the housing. a housing with branch pipes for supplying and removing liquid from it; a vertical shaft rotatably mounted in the housing, fixed on the shafts one above the other and at a distance from each other; a plurality of contact stages formed by spirally formed bands extending from an axis and having sides flanged towards the axis; a device for transferring liquid from one contact stage to another; , the device is made in the form of an annular pocket fixed on the inner wall of the housing and used to collect the liquid flowing from the contact stages; an overflow tray arranged in the space between the contact stages; a receiving end of the tray communicates with an annular pocket collecting liquid flowing from the contacting stage, and an outlet end located above the lower contacting stage;
According to the invention, a waveform is provided that substantially traverses the band.

In such rotating film columns, the contact surface between gas and liquid is further increased by fractionation and atomization of the liquid when it falls onto a corrugated spiral band.

The effect of liquid fractionation and atomization is ensured by dumping the liquid from a stationary overflow tray onto a corrugated band that rotates with the contact stage.

That is, liquid is dumped from the stationary overflow tray while the band is rotating with the contact stage, so that the fluid flows along the band surface as the liquid stream falls onto the band.

Since the band has a small wave shape, the liquid stream flows over the band surface and breaks up into droplets or spray.

In this case, the liquid contacts both the outer and inner surfaces of the band.

The resulting liquid spray then settles on the inner surface of the band under the action of centrifugal force and causes additional agitation, ie mixing of the liquid film already coated on the inside of the band.

The increased contact surface between gas and liquid by spraying and the additional agitation of the liquid film settled by spraying serve to increase the efficiency of mass transfer and to increase the efficiency of the contacting stage, for example in rectification processes.

The top side of the band should preferably be located at a greater distance from the axis than the bottom side.

The inner surface of the band is therefore more accessible to the spray of liquid cast from the overlying tray, and the corrugations serve to spray the liquid along its entire length.

It is advantageous to increase the height of the corrugations along the width of the band with increasing distance from the top of the band.

For this reason, the liquid flow easily approaches the lower part of the waveform as well as the upper part of the waveform.

It is convenient to provide a drain orifice at the bottom of the overflow tray.

An overflow tray so designed distributes the same amount of liquid to many points on the same contact stage.

This serves to develop a contact surface and increase agitation of the liquid film.

The overflow tray is preferably secured to at least one vertical rond attached to the side wall of the housing that is rotatable to provide control of the position of the overflow tray with respect to the contact stage.

Such an embodiment of the overflow tray makes it possible to change the point of supply of liquid to the contact riser without stopping the column.

In this case, an optimal method of distributing the liquid over the contact ridge can be found which gives the largest surface of contact and the highest degree of agitation of the liquid film.

The most preferred location of the overflow tray on the contacting stage can be found empirically, for example using the column distillate quality as an optimum criterion, without stopping the column.

The present invention will now be described in more detail with reference to the accompanying drawings.

A rotating film column for making contact between gas and liquid has a cylindrical housing 1 (Fig. 1), which has a branch pipe 2 for supplying gas into the bottom of the column and a branch for removing gas from the top of the column. It has a pipe 3, a branch pipe 4 for feeding liquid into the middle part of the column, a branch pipe 5 for feeding liquid into the top of the column, and a branch pipe 6 for removing liquid from the column.

A vertical shaft 8 is coaxially mounted in the housing 1 and is rotatable in bearings 7.

A pulley 9 is provided at the upper end of the shaft 8 and is rotated by a drive mechanism (not shown).

The contact stages 10 are fixed on the shaft 8 at a limited distance from each other.

The working surface of each contact stage 10 consists of two bands 11 (Figs. 1 and 2).
formed by

The band 11 is shaped like a spiral extending from the axis 8 and is flanged towards this axis.

That is, the side portion 12 of the band 11 is bent toward the axis 8.

The two bands 11 form a double spiral spiral.

The flanged edges 12 are used to retain liquid on the inner surface of the band 11, ie the surface facing the axis 8.

The outer end 13 of the band 11 is narrowed in order to collect the liquid film in the flow prior to dumping the wall of the housing 1.

The radial puller 14 is used to secure the band 11 to an annular cup 15 which also serves as a central hub.

An annular cup 15 is used to mount the contact stage 10 on the shaft 8.

The column also includes equipment for flowing liquid from one contacting stage 10 to another.

These devices include an annular pocket 16 fixed on the inner wall of the housing 1 and an overflow tray 17, 18.1 communicating with the annular pocket 16 and located in the space between the contact stages 10.
9 (FIG. 2) are included.

The annular pocket 16 receives the liquid that falls out of the rotary contact stage 10; therefore, the outer end 13 of the band 11 is somewhat higher than the pocket 16, as shown in FIG.

The bottom of pocket 16 has an orifice 20 through which the pocket communicates with overflow trays 17, 18, 19 (FIG. 2).

The latter is used to supply liquid from the pocket 16 onto the contact stage 10 below.

In the same cross section between the contact stages 10 there are three trays 17,1
8.19, which is curved in the horizontal plane.

Band 11 is provided with substantially transverse corrugations 21 and 22 (FIG. 3).

The corrugations 21 are made on the flanged side 12 of the band 11, while the corrugations 22 are made on the irrigation part I, on which the liquid film is usually formed.

However, the corrugations 21 can only be on the flanged sides 12, such as on band 11a (FIG. 4) or likewise on band Ilb (FIG. 5), and the corrugations on the irrigation surface are only on the sides of band Ilb. It can be inclined to some extent with respect to the part.

The embodiment of the invention shown in FIG. 1 has a contact stage 10, the band 11 of which is constructed as shown in FIG. 3, but it is also possible to use bands 11a (FIG. 4) or 11b (FIG. 5). can.

Band 11a (FIG. 4) is used when it is desired to minimize the residence time of the liquid on each contacting stage and thus in the entire column.

The corrugations 21 created on the sides of the band 11a do not increase the amount of liquid on the rotating contact stage, ie do not increase the dynamic delay of the contact stage with respect to the liquid.

However, in this case the waveform is
18.19 (Figure 2) serves to promote spraying and atomization of the liquid dropped.

Bands 11 (FIG. 3) and 11b (FIG. 5) are used when it is necessary to increase the residence time of the liquid on the contacting stage 10.

The corrugations 22 (Fig. 3) or 23 (
The four points in the gap between Figure 5) increase the amount of liquid on the band.

This increases the residence time of the liquid in the column and can be very useful in some cases, for example in processes involving chemical reactions.

Waveform 22 (FIG. 3) together with waveform 21 serves to spray and atomize the liquid and thus to increase the contact time.

At the bottom of the trays 18 and 19 (FIG. 2) orifices 24 are provided for distributing the liquid at desired points on the contact stage 10 in order to favor the development of the contact surface and to increase the degree of agitation of the liquid film. .

Since the tray 17 is used to supply liquid only into the annular cup 15, it has no orifice at its bottom and liquid must flow therefrom only at the open end.

According to the invention, the set of 1-rays 17, 18, 19 are arranged in bearings 28 and 29 (FIG. 1) near the wall of the tower housing and are rotatable in ordinary vertical rods 25, 26, 27 at their dead ends.

Rods 25, 26, and rod 2 not visible in Figure 1
1 extends through the pocket 16 through the opening 20.

The places where the rods 25, 26, 27 pass through the bottom of the trays 17, 18, 19 (FIG. 2) are hermetically sealed.

One end of each of the ronds 25, 26, 27 extends outwardly and is provided with a rotating handle 30 (FIG. 1).

Rotation of the handle 30 moves the tray 1γ in the transverse plane of the tower.
, 18.19 (Figure 2).

FIG. 2 illustrates one possible embodiment of the tray position.

In particular, only one tray or as many as four trays can be arranged in the same cross-section of the column.

In order to distribute the liquid more evenly on several different trays 17, 18, 19 at the same time, the annular pocket 16 may be divided into three individual sectors by transverse partitions 31.

In another embodiment of the rotary film column (FIG. 6), the shape of the band forming the contact stage is modified.

The column has a housing 32 with a vertical shaft 33 and a contact stage 34 attached to the shaft 33.

The overflow device includes annular pocket 35 and pocket 3.
5 in the form of an overflow tray placed on top.

The contact stage 34 consists of a spirally wound band 37 (Fig. 6.7.8
), whose upper side 38 (FIG. 6) and lower side 39 are flanged toward the shaft 33.

The band 37 is a radial rib 4 connected to a central hub 41.
Fixed above 0.

The upper side 38 of the band 37 is, according to the invention, at a greater distance from the axis 33 than the lower side 39 of this band.

Moreover, the height of the waveform 42 (FIG. 9) of the band 37 is from h to H along the width of the band 37 in the direction from its upper side 38.
It becomes larger at t.

Such a design of the contact stage 34 (FIG. 6) facilitates the permeation of the liquid stream flowing down from the tray 36 in the soil to all portions of the corrugations 42 made on the irrigated portion of the band 37.

Rotating film columns operate as follows when used in rectification processes.

The vapors of the mixture to be separated, which have a reduced content of readily volatile components, are fed into the column from the bottom through branch 2 (FIG. 1) and taken off therefrom through branch 3.

The initial liquid mixture of the components to be separated is fed into the column via branch 4, where it is delivered into annular pocket 16.

The reflux residue is fed into the column through branch pipe 5, the reflux filling the top annular pocket 16 and then flowing down along trays 17 and passed to the contacting stage 10.

The top contact stage 10 is used as a separation stage.

It is used for mist removal.

The liquid settling on the top contact stage 10 is then dumped into the top annular pocket 16.

From pocket 16 liquid flows into trays 17, 18, 19 (FIG. 2) located below the pocket.

The liquid is then distributed onto the underlying shadow stage 10.

From the tray 17 the liquid is transferred into the annular cup 15.

From trays 18 and 19 liquid flows through open ends and drain orifices 24 directly onto band 11 of rotating contact stage 10.

In this case, the liquid is sprayed and atomized.

The liquid spray settles onto the working (irrigation) surface of band 11 and agitates the liquid film.

As a result, the strength of mass transfer increases.

From the annular cup 15 the liquid also flows into the band 11 under the influence of centrifugal force.

A spray of liquid from the rotating contact stage 10 is delivered to the column housing 1.
The liquid is then poured into the pocket 16 below.
Flows inside.

The vapor of the mixture to be separated comes into contact with the liquid film permeated into the bands 11 and also with the mist suspended in the gaps between the bands 11.

During the operation process of the tower, the trays are connected to the corresponding Rondo 25,
It can be adjusted to any position by turning 26.27.

1 to Ray 17, 18.1 to obtain the most dog contact surface and agitation degree on band 11 without stopping the tower.
Make it possible to arrange 9.

In this case, the quality of the column distillate can be used as a criterion for optimum operation.

The column shown in FIG. 6 operates similarly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view of a rotary film column according to the present invention, FIG. 2 is a cross-sectional view taken along line H-U in FIG. 1, and FIG.
4 is an enlarged isometric view of a band element forming a contact step according to the invention, FIG. 4 is an enlarged isometric view of a second embodiment of a band according to the invention, and FIG. 5 is an enlarged isometric view of a third embodiment of a band according to the invention. 6 is an enlarged isometric view of a band element, FIG. 6 is a longitudinal cross-sectional view of another embodiment of a rotating film column according to the present invention, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 8 is a cross-sectional view taken along the line ■--■ in FIG. 6, and FIG. 9 is an enlarged isometric view of the band elements forming the contact stage of the column shown in FIG. 6 according to the present invention. 1... Housing, 2... Gas inlet branch pipe, 3... Gas outlet branch pipe, 4, 5...
Liquid inlet branch pipe, 6...-Liquid outlet branch pipe, 10...
...Contact stage, 11, lla, 11b...Band, 12...Band side part, 16...
Annular pocket, 17, 18, 19... Overflow tray, 2L22, 23... Waveform.

Claims (1)

[Claims] 1. A housing 1, a branch pipe 2 for supplying gas into the bottom of the housing 1, a branch pipe 3 for removing gas from the top of the housing 1, and a branch pipe 3 for removing gas from the top of the housing 1. Branch pipes 4 and 5 for supplying liquid, branch pipe 6 for removing liquid from housing 1, a vertical shaft 8 rotatably mounted within the housing, and a vertical shaft located on said vertical axis. are mounted above and below each other at a distance, and the vertical shafts 8
a contact step 10 formed by a spiral band branching from said vertical axis with flanged sides in the direction of A device for transferring from one contacting stage 10 to another, as well as a device arranged in the space between said contacting stages, the receiving end of which collects liquid flowing down from the contacting stage 10 lying above it. In a rotary film column for contacting gas and liquid, the band comprises an overflow tray 17, 18, 19 communicating with the annular pocket and having its discharge end located above the contact stage below. A rotary film column characterized in that 11 is provided with waveforms 2L22 and 23 in a direction substantially transverse to the band. 2. The rotary film tower according to claim 1, wherein the upper side 38 of the band 37 is located at a greater distance from the axis 33 than the lower side 39 thereof. 3. The rotary film tower according to claim 1, wherein the height of the waveform 42 increases along the width of the band 37 as the distance from the upper side 38 of the band 37 increases. 4. A rotary film column according to any one of claims 1 to 3, wherein the drain orifice 24 is made at the bottom of the overflow trays 18, 19. 5 Overflow trays 17, 18, 19 in the cross section of the column
At least one vertical rod 25 mounted so that the overflow tray 17, 1B or 19 can rotate close to the side wall of the housing 1 in order to control the position of the overflow tray 17, 1B or 19 relative to the contact stage 10.
, 26 and 27.
The rotary film column according to any one of the above items.