UA124773C2 - COLUMNED COLLECTIVE MASS EXCHANGE DEVICE - Google Patents

Abstract

The invention relates to column apparatus in which mass transfer processes take place in the vapor-liquid system. The column mass exchanger of cyclic action contains the case in which plates with contact elements are placed, and the valves fixed on the movable rods connected to the driving mechanisms which move rods up and down through the set interval of time, and valves alternately open and close synchronously. overflow openings of even and odd according to the order of arrangement of plates at continuous giving in a column of steam and liquid. According to the invention on the valves are placed contact elements, as well as on the plate, the free cross section of the plate is 2-20%, and the ratio of the cross-sectional area of the overflow hole and the total hole area of the contact elements from 2: 1 and more provides fluid overflow holes through these holes and the holes of the contact elements. The technical result of the invention is to increase the efficiency of mass transfer between liquid and steam on the plates of the column apparatus, reduce the specific consumption of heating steam and increase the capacity of the apparatus for steam and liquid.

Description

The invention relates to column apparatuses in which mass exchange processes occur in the vapor-liquid system, and can be used as bragorectification equipment for the production of edible ethyl alcohol and bioethanol in the alcohol industry, as well as in the chemical, oil refining, petrochemical, pharmaceutical and other industries.

There is a well-known rectification column with controlled cycles, which includes a body and plates with contact elements placed on their canvas and devices for transferring liquid from plate to plate (patent of Ukraine and utility model Mo 116565 ВО10О 3/30 (2006/01). Rectification column with controlled cycles / Yu.V. Buliy, A.P. Dmytruk, P.A. Dmytruk - Application y201612611.

Announced on 12.12.2016; Publ. 05/25/2017, Bul. Mo 10). The latter are equipped with overflow pipes, the lower ends of which are inserted into the glasses and form hydraulic seals to exclude steam breakthrough.

The openings of the overflow pipes are closed and opened by valves fixed on movable rods in such a way that some of them are located on odd-numbered plates, others - on even plates. To prevent spillage of liquid through the openings of the overflow pipes, the valves are sealed by springs when they are closed. The rods are connected to the drive mechanisms and due to their action, the valves move up and down.

A distillation column with controlled cycles works as follows. Fluid is continuously supplied to the feed plate. Heating steam is constantly supplied to the lower part of the column. The drafts alternately move up and down at controlled time intervals, and the valves attached to them synchronously close and open the openings of the overflow pipes in such a way that the overflow of liquid over the plates occurs in two consecutive stages, which are repeated periodically in time alternately: in the first stage, the liquid overflows from of each odd plate to each subsequent even plate in order of location, at the second stage - from each even plate to each subsequent odd plate.

The specified delay time and liquid overflow time are maintained by the controller, so the delay and liquid overflow cycles occur according to the specified algorithm.

The disadvantage of the known design of the rectification column is a decrease in the efficiency of mass exchange between liquid and steam due to a decrease in the free cross-section of the plates (the ratio of the total area of the holes of the contact elements located on the plate to the area of the plate) by 96 due to the presence of overflow devices and longitudinal mixing of the liquid on adjacent

From the plates during its overflow, the complexity of the design, an increase in its cost due to the presence of overflow pipes and glasses on each plate, as well as a decrease in the throughput of the column for steam and liquid.

The invention is based on the task of increasing the efficiency of mass transfer between liquid and steam on the plates of the column apparatus, reducing its cost, the specific consumption of hot steam, and increasing the throughput of the apparatus for steam and liquid.

The task is solved by the fact that the column mass exchange apparatus of cyclic action contains a body in which plates with contact elements are placed, and valves fixed on movable rods connected to drive mechanisms that move the rods up and down for a given time interval, and the valves alternately open and close the overflow holes of even and odd-numbered plates in the order of arrangement of the plates in synchrony, during the continuous supply of steam and liquid to the column. According to the invention, contact elements are placed on the valves, as well as on the web of the plate, the free cross-section of the plate is 2-20595, and the ratio of the cross-sectional area of the overflow hole and the total area of the holes of the contact elements from 2:1 and more ensures the overflow of liquid at the moment of opening the overflow holes through these holes and the holes of the contact elements.

The design of the proposed column mass exchange device allows to increase the free cross-section of the plates by 15-20 95 in comparison with the closest analogue due to the absence of hydraulic valves and the equipping of valves with contact elements placed, as well as on the web of the plates. The technical solution simplifies the design of the device, allows you to reduce its cost, reduce the specific consumption of heating steam to 30 95 and eliminate the longitudinal mixing of the liquid on adjacent plates during its overflow.

To increase the throughput capacity of the mass transfer device through the liquid by overflowing the liquid through the overflow holes and its "fall" through the holes of the contact elements, the column device is equipped with mass transfer drop plates - lattice, grate, tubular, mesh (flat or wavy), scaly, etc. A layer of liquid on the canvas of the plate, through which steam bubbles, is formed under steam pressure. "Failure" of the liquid occurs due to a decrease in the speed of steam in the holes of the contact elements at the moment of opening the overflow hole.

The free cross-section of the failure plate is selected under the condition that there is no "failure" of liquid with a steam consumption that does not exceed the standard, and is 2-20,905. Under such conditions, the plate has a low hydraulic resistance. When reducing the free cross-section (less than 2 95) by reducing the number of contact elements, the efficiency of mass transfer over the entire area of the plate decreases, the resistance of the plate increases, and liquid is transferred from the lower plates to the upper ones (splash).

An increase in the free cross-section (more than 20 95) by increasing the number of contact elements requires an increased consumption of steam to keep the liquid on the plates more than standard.

The ratio of the cross-sectional area of the hole for liquid overflow and the total area of the holes of the contact elements of the plate from 2:1 and more ensures an effective overflow of liquid from the plate to the plate at the moment of opening the overflow holes without hydraulic seals. During the overflow period (at the moment of upward movement of the valves and opening of the overflow holes), the steam velocity in the holes of the contact elements at the above ratio instantly decreases to 3.5-1 m/s (becomes less than the critical one at which the liquid is retained on the plate), and the plate becomes leaky: the liquid simultaneously overflows through the overflow hole and spills (falls through) through the holes of the contact elements. During the period of mass exchange (after the thrust moves downward at the moment the overflow holes are closed by the valves), the steam velocity in the holes of the contact elements instantly increases, becomes greater than the critical one, and the "fall" of the liquid stops. During this period of the cycle, the plate becomes unbreakable, and a specified time delay of the liquid and its contact with steam (mass transfer) occurs on its surface.

It is known that for various types of sag plates there is a lower limit of their operating range - the critical speed of steam in the holes of the contact elements, at which the liquid is retained on the plate (below which the liquid falls through these holes), and the upper limit - the critical speed of steam in the holes of the contact elements , during which the transfer of liquid from the lower plates to the upper plates begins. For example, for mesh plates, the "fall" of liquid stops at a steam velocity in the holes of 4-5 m/s, for scaly plates at 6.5-7.5 m/s. The upper critical speed for the operation of mesh plates is 8 m/s, for the operation of scaly plates - 16 m/s.

If the ratio of the cross-sectional area of the hole for liquid overflow and the total area of the holes of the contact elements of the plate is smaller than 2:1, the speed of steam in the holes of the contact elements at the moment of opening the overflow holes decreases to a value that exceeds the lower critical speed, so the liquid overflow through the overflow holes and its "failure" through the holes of the contact elements does not occur.

З The columnar mass exchange apparatus of cyclic action is explained by the drawing, which shows its cross-section.

The column apparatus includes a body 1, plates 2 with contact elements C placed on their canvas with holes for the passage of steam and overflow of liquid from plate to plate.

The overflow holes are closed and opened by valves 4 and 5, fixed on movable rods 6 and 7 in such a way that some of them are located on odd-numbered plates, others - on even plates. To prevent spillage of liquid through the overflow holes when they are closed, valves 4 and 5 are sealed by springs 8. Rods b and 7 are connected to drive mechanisms 9 and 10, respectively, and due to their action, valves 4 and 5 move up and down.

The column mass exchanger of cyclic action works as follows. The feed plate (in this case, the upper odd plate) continuously receives liquid. Heating steam constantly enters the lower part of the device. In the initial period of operation, thrust b is in the lower position, in which valves 4 close the overflow holes until the nominal level of liquid on the upper plate is reached. At the same time, mass exchange takes place on its canvas.

The time interval for reaching the nominal level is equal to the retention time of the liquid on the plates of the device, which is determined experimentally depending on the qualitative composition and volume of liquid entering the feeding plate. During this period, the thrust 7 is in the lower position, in which the valves 5 close the overflow holes located on the paired plates.

After reaching the nominal level on the upper plate, the drive mechanism 9 raises the rod 6 to the upper extreme position, the valves 4 rise to a certain height, which is equal to the stroke of the cylinder rod, the overflow holes of the odd plates open, and the liquid overflows from the upper (odd) plate to the one located below ( steamed) plate. After the end of the liquid overflow, under the action of the drive mechanism 9, the thrust 6 moves down to the position in which the valves 4 close the overflow holes of odd plates. During this period, mass exchange takes place on the lower (paired) plate. After the specified liquid delay time, the drive mechanism 10 raises the rod 7 to the upper extreme position, the valves 5 synchronously rise to the specified height, open the overflow holes of the even plates, and the liquid overflows from the even (second, counting from the top) plate to the odd (third, counting from the top ) the plate located below. After the end of the liquid overflow, under the action of the drive mechanism 10, the thrust 7 with the valves 5 attached to it moves down to the position in which the valves 5 close the overflow holes of the paired plates. During this period, mass exchange takes place on odd plates.

Then all the following plates are similarly included in the work. The liquid from the last plate is poured into the cubic part and removed from the device.

During the operation of the column mass exchange apparatus, under the action of the drive mechanisms 9 and 10, the rods 6 and 7 alternately move up and down, and the valves 4 and 5 attached to them synchronously close and open the overflow holes in such a way that the overflow of liquid on the plates occurs simultaneously through the overflow holes and the holes of the contact elements in two consecutive stages, which are repeated periodically in time alternately: in the first stage, the liquid flows from each odd plate to each subsequent even plate in the order of location, in the second stage - from each even plate to each subsequent odd plate. The liquid retention time on the column plates depends on the amount of liquid and its qualitative composition, is determined experimentally and is supported by the controller, so the cycles of liquid retention and overflow occur according to a given algorithm.

The technical result of the use of the invention consists in increasing the efficiency of the mass transfer between liquid and steam on the plates of the column apparatus, reducing its cost, the specific consumption of hot steam, and increasing the throughput of the apparatus for steam and liquid.

Claims (1)

FORMULA OF THE INVENTION A column mass exchange apparatus of cyclic action, containing a housing in which plates with contact elements are placed, and valves fixed on movable rods connected to drive mechanisms that move the rods up and down for a given period of time, and the valves are alternately opened synchronously and close the overflow holes even and odd according to the arrangement of the plates during the continuous supply of steam and liquid to the apparatus, which is distinguished by the fact that contact elements are placed on the valves, as well as on the web of the plates, the free section of the plate is 2-20 95, and the ratio the cross-sectional area of the overflow hole and the total area of the holes of the contact elements from 2:11 and more ensures the overflow of liquid at the moment of opening the overflow holes through these holes and the holes of the contact elements.