RU2445996C2 - Rectification column - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to mass-transfer apparatuses for rectification of fluid mixes. Rectification column comprises still, partial condenser, housing with process branch pipes consisting of rings with horizontal baffles arranged there between. Said baffles have holes provided with heat-transfer devices made up of coils. Horizontal baffles at column bottom section are equipped with contact branch pipes including tangential swirlers, deflector, fluid discharge branch pipe, outer cylinder and hydro lock barrel. Heat-transfer devices are arranged in steam space of rings above horizontal baffles and provided with, at least, one plate flanged on one side and arranged horizontally with clearance between coil turns. Restrictors are arranged in coils to maintain preset consumption of coolant. Extra swirlers with tangential channels are arranged at top end of cylindrical hydro lock barrels. Bottom faces of outer cylinder and fluid discharge branch pipe are located below channels of steam from tangential swirlers. Ratio of said swirler diameter to said branch pipe diameter is made equal to D_s/D_b=1.5-3.0.

EFFECT: higher efficiency, reduced overall dimensions and metal consumption.

7 cl, 7 dwg

Description

The invention relates to heat and mass transfer apparatus for carrying out the process of distillation of a mixture of liquids by distillation methods used in the alcohol, petrochemical, chemical, microbiological, wood chemical and food industries.

A known plate for contacting gas (vapor) with a liquid [1], including a horizontal partition, contact devices made in the form of hollow vertical cylinders, coaxially mounted with hydraulic shutter devices, and tangentially directed holes for passage of gas vapor are made in the upper part of the contact device case closed by a lid with a steam pipe passed through it.

However, the column, consisting of such plates, has low efficiency and metal consumption. According to data known in the literature, the effectiveness of such a step is 0.3-0.8, which is clearly not enough. The metal consumption is caused by a large number of plates and a non-compact structural arrangement of contact devices on horizontal partitions.

Known film plate Leva [2], consisting of tsar, in which are placed horizontal partitions (sheets) with holes and nozzles for the passage of steam and flowing liquid.

This device has a low hydraulic resistance and a simple design, but the effectiveness of such plates according to Murphy does not exceed 0.1.

The closest technical essence is the contact plate for vortex heat and mass transfer apparatus [3], consisting of a web (horizontal partition), on which a contact pipe equipped with a swirl is installed, and a fender with an internal and external cylinders is coaxially placed. The canvas is equipped with units for supplying and discharging liquid from the plate and supplying liquid to the swirl. The inner cylinder is made with a blind base to form a cavity in which the liquid phase supply pipe is placed, the lower cut of the outer cylinder is made with a flange located with a gap to the wall of the apparatus and the plate blade to form a pocket, the cavity of this pocket communicating with the fluid supply unit to the swirl and in the annular space between the contact pipe and the outer cylinder of the chipper installed heat exchanger connected to the pipelines of the coolant system.

However, this device also has low efficiency and high metal consumption. Low efficiency is due to the weak strengthening of vapors on the contact plate, since rising steam comes into contact only with the flowing liquid at the stage, and this is not effective enough, which leads to a large number of plates and increases the metal consumption of the column.

The invention solves the problem of increasing the efficiency of the column, reducing its size and metal consumption due to:

obtaining steam from additional reflux with a high concentration of volatile components, which allows to strengthen the rising steam and thereby increase the efficiency of the rectification process;

intensive mixing of steam at the steps caused by the transverse movement of a portion of the rising steam to the surface to be cooled relative to the movement of the main flow of the rising steam;

increasing the separating ability of vapors on the steps by providing fractional condensation directly on the steps (consisting in obtaining condensate from the rising steam with a higher concentration of high boiling components (hardly volatile) than in the pair itself, which ensures an increase in the concentration of volatile (low boiling) components in the rising pair and increases separation efficiency).

The technical result is:

in obtaining additional phlegmy on the surface of the coils placed in the steam space of the tsar under horizontal partitions;

in obtaining additional steam with a high concentration of volatile components by heating and evaporating additional reflux, placed on the surface of the plates flanged from the ends, and horizontally installed with a gap under the coils of the coils;

in the formation on the surface of plates flanged from the ends of the condensate, with an increased concentration of a hardly volatile component (TLC) of a separable mixture caused by the effect of fractional distillation;

intensive mixing of steam caused by the transverse movement of a portion of the rising steam to the surface to be cooled relative to the movement of the main stream of the rising steam.

All this makes it possible to increase the concentration of the volatile component in the vapor and thereby increase the efficiency of the rectification process, reduce the height of the column, and therefore reduce its dimensions and metal consumption, which is also facilitated by the installation of an additional swirl with tangential channels at the upper end of the cylindrical hydraulic shutter cup.

The specified technical result is achieved by the fact that the distillation column, including a cube, a reflux condenser, a condenser, a housing with technological nozzles, consisting of tsarg, between which are placed horizontal partitions with openings, equipped with heat exchangers made in the form of coils from pipe turns connected to the system pipelines coolant, in the lower part of the column horizontal partitions are equipped with contact pipes, including a tangential swirler, fender device, pipe a liquid discharge, an outer cylinder and gidrozatvornuyu cavity formed of a cylindrical cup gidrozatvornogo; heat exchangers are placed in the Tsar’s vapor space under horizontal partitions and are equipped with at least one plate flanged from the ends, horizontally mounted with a gap under the coil turns, and throttling devices are placed in the coils to maintain a given refrigerant flow, with an additional installed on the upper end of the cylindrical hydraulic shutter glasses tangential swirl, and the lower ends of the outer cylinder and the nozzle for draining the liquid are located below the channels for the passage of gas and in the swirler, the ratio of the swirl diameter D _s to the diameter of the pipe for draining the fluid D _p passing through it is maintained equal to D _s / D _p = 1.5-3; in the upper part of the column between the coil and the horizontal partition there is a flanged washer; the upper end of the pipe for the outlet of the coolant is connected by a pipe with a fitting for supplying refrigerant to the reflux condenser; the ratio of the cross-sectional area of the channels f for the passage of steam in the tangential swirler to the cross-sectional area of the channels f ₁ for the passage of steam of the subsequent upstream swirl is maintained equal to f / f ₁ = 1.05-1.25; the plate flanged from the ends is made with at least one flanged hole, and the ratio of the flanging height of the ends of the plate h ₁ to the flanging height of the holes h is 0.8-0.99; at least one additional heat-exchange device is placed in the Tsarg steam space, for example, in the form of a coil equipped with an additional plate flanged from the ends; the surface of the heat exchanger is made equal in value in accordance with the dependence F = Q / q = Q / (10 ² -10 ⁵ ) m ² .

Placement of heat exchangers in the Tsarg steam space, under horizontal partitions, at least one plate flanged from the ends, horizontally installed with a gap under the coil turns, as well as placement of throttling devices in the coils to maintain a given refrigerant flow rate, installation at the upper end of the cylindrical hydraulic shutter glasses of an additional tangential swirl, the placement of the ends of the outer cylinder and the pipe to drain the liquid below the channels for the passage of steam into gentsialnom swirler and the maintenance ratio of the diameter D _of the swirler to the diameter of the nozzle for discharging the liquid L _n equal to 1.5-3 improves the efficiency of the separation column, to reduce its size and metal.

The placement of heat exchangers (coils) in the steam space of the drawer under the horizontal partitions eliminates their contact with the flowing liquid, thereby preventing overcooling of the flowing liquid. And most importantly, it allows you to get additional phlegm from rising steam, not mixed with flowing liquid, which provides increased efficiency.

The installation under the coils of coils of plates flanged from the ends and placed with a gap to their surface prevents premature ingress of additional reflux into the flowing liquid, ensures its heating by rising steam, and then its evaporation to produce additional steam, which contains a higher concentration of volatile components than in rising steam, which increases the efficiency of the column. And the presence of a gap prevents the contact of additional reflux with the surface of the coil and thereby prevents overcooling of reflux. The presence of flanging allows you to hold additional reflux in the required volume on the surface of the plates, which provides the desired contact surface.

The presence of throttling devices makes it possible to maintain a predetermined liquid temperature (wall temperature) in the coil cavity by supplying a certain flow rate of refrigerant. In the absence of throttling devices, maintaining the wall temperature is not provided in the required range, which leads to the loss of the effective operation of the column as a whole.

The installation of an additional tangential swirl at the upper end of the cylindrical hydraulic shutter cups allows you to create two zones of steam contact with the liquid in the drawer (two plates in one drawer), which naturally reduces the metal consumption of the stage and increases its efficiency due to a more intense twisting of the steam flow in the drawer.

The installation of the ends of the outer cylinder and the nozzle for draining the liquid below the level of placement of the channels for the passage of gas in the swirl ensures stable and efficient operation of the column by creating a water seal (which prevents the passage of steam through the channel for the passage of fluid formed by the outer cylinders and nozzle).

Maintaining the ratio of the diameter D _of the swirler to the diameter of the nozzle for discharging the liquid L _n therethrough equal to 1.5-3 enables intensive aeration of the liquid in the gap formed by the nozzle and swirler. When the ratio D _s / D _p <1.5 is satisfied, the volume of the aerated liquid at the stage decreases, which is not effective. When the ratio D _s / D _p > 3 is fulfilled, the separation efficiency decreases due to incomplete contact of the liquid with the steam jets leaving the swirler channels (that is, intensive aeration of the liquid in the central part of the stage is not provided).

Installation in the upper part of the column between the coil and the horizontal partition of the flanged washer allows eliminating the ingress of flowing liquid from the horizontal partition onto the surface of the coil placed underneath, and this prevents the mixing of additional reflux formed on the coil with the flowing liquid, which improves the efficiency of the stage.

The connection of the upper part of the pipe to the coolant with the nozzle for supplying refrigerant to the reflux condenser ensures that water (refrigerant) is supplied to the cavity of the reflux condenser, which is close to the temperature of the steam in the reflux condenser, which makes it possible to obtain reflux in the reflux condenser with a temperature close to the temperature of the steam in contact with it, and it increases efficiency.

Fulfillment of the ratio of the cross-sectional area of the channels for the passage of steam in the tangential swirl f to the cross-sectional area of the channels of the subsequent upstream tangential swirl f ₁ equal to f / f ₁ = 1.05-1.25 allows you to maintain the same speed of steam exit from the channels along the height of the column, which provides the required twisting the gas-liquid mixture along the height of the column. The decrease in steam velocity along the height of the column is due to the condensation of a portion of the rising steam on each drawer (due to a change in steam consumption over the height of the column).

The fulfillment of the ratio f / f ₁ <1.05 is non-technological in manufacturing. When the ratio f / f ₁ > 1.2 is not achieved the same twist of the flow along the height of the column, and a decrease in twist leads to a decrease in the separation efficiency.

Performing holes on the flanged plates at the ends of the holes, while respecting the ratio of the flanging height of the plate h ₁ to the flanging height of the holes on it h equal to h ₁ / h = 0.8-0.99, allows the liquid to drain through the flanging of the plates and thereby prevents reflux from entering the coil surface , and also allows you to increase the speed of steam along the section of the drawer, which increases efficiency. When the ratio h ₁ / h <0.8, a small amount of reflux on the plate is provided, which reduces the efficiency. When the ratio h ₁ / h> 0.99 is fulfilled, phlegm due to distortions during installation starts to flow through the holes, falling on the heat transfer surface, which is not effective.

Placing at least one additional heat exchanger (coil) in the steam chamber and the presence of a plate flanged from the ends underneath it allows repeatedly obtaining additional reflux at the stage and evaporating it to obtain a secondary vapor with a higher concentration of LLA than in the main pair, leading to increased efficiency.

The implementation of the surface area of the heat exchanger device (coil) in accordance with the dependence F = Q / q = Q / (10 ² -10 ⁵ ) m ² allows the rectification process to be performed at a given heat load and thereby provide each stage with additional reflux based on the required number of theoretical separation stages (the amount of which varies over a wide range) and allows the rectification process to be carried out with high efficiency. Where q is the specific thermal load on the condensing pair on the cooled surface, equal to q = (10 ² -10 ⁵ ) W / m ² ; Q is the heat expended in the condensation of the rising steam at the stage, W.

When performing F <Q / 10 ⁵ (m ² ), a sufficient amount of reflux on the steps is not provided, which reduces the separation efficiency.

When F> Q / 10 ² (m ² ) is fulfilled, the consumption of raising steam decreases, which is no longer sufficient for efficiently carrying out the rectification process, in this connection the efficiency of the upper stages and the column as a whole decreases.

Figure 1 shows a General view of a single-element distillation column.

Figure 2 presents the case of a multi-element distillation column.

Figure 3 shows the upper part of the body of a single-element distillation column.

Figure 4 presents the lower part of the housing of a single-element contact column.

Figure 5 shows the upper part of a single-element column with the placement of plates flanged from the ends between the turns of the coil.

Figure 6 shows the upper part of the housing of a single-element distillation column with the placement of additional heat transfer devices.

7 shows a throttling device located in the housing of the coil tube.

The distillation column consists of a cube 1, equipped with a heat-exchange jacket 2, heaters 3, a system of technological pipes 4, and bosses for automation devices 5. It also includes a reflux condenser 6, a condenser 7, a housing with technological pipes 8, consisting of a drawer 9, in which horizontal partition 10 with holes. In the lower part of the column, horizontal partitions 10 are equipped with contact nozzles 11, including a swirl with tangential channels 12, a fencing device 13, a nozzle for draining the liquid 14, an external cylinder 15, and a water seal cavity 16 made of a cylindrical water seal glass 17. In the vapor space there is a casing 9 under horizontal baffles 10 are installed coils 18, equipped with at least one plate 19, flanged from the ends up and horizontally installed with a gap under the coil of the coil 18, made of tubes 20, in which throttling devices 21 are placed, for example, made of a cylindrical sleeve with a calibration hole 22 to create a given flow rate of refrigerant. The ends of the tubes 20 are connected by means of couplings 23 to a coolant system consisting of pipelines for supplying cold water 24 and for discharging heated water 25, the upper part of the pipeline 25 being connected to a fitting 26 for supplying refrigerant to the reflux condenser 6 by a pipe 27. At the upper end of the cylindrical hydraulic shutter glasses 17 an additional tangential swirler 28 is installed. Moreover, the lower ends of the outer cylinder 15 and the nozzle for draining the liquid 14 are located below the channels for the passage of steam in the tangential swirls 12 and 28. On the plates, it is selected At the ends 19, flanged holes 29 can be made. Flanged washer 30 is installed in the gap between the horizontal partitions 10 and the coils 18. At least one additional coil 31 (Fig. 6) equipped with an additional plate 32 is placed in the steam chamber of the drawer 9; beaded from the ends. Tsars 9 are pulled together by pins 33 (figure 2).

Distillation column operates as follows.

The vapor of the mixture rises from the cube 1 of the column, passes through the channels of the tangential swirls 12 and 28, located in the lower part of the column, interact with the flowing liquid on the horizontal partitions 10, forming a developed interfacial surface and intense mass transfer. In this case, part of the rising steam condenses on the surface of the coils 18 with the formation of reflux, which then flows onto the flanged plates 19, is heated there by rising pairs, which ensures its partial evaporation and the formation of condensate on its outer surface, which helps to strengthen the vapor along the height of the column. Then the mixture vapors enter the upper (reinforcing) part of the column, and the liquid through the nozzles 14 enters the cube. Vapors pass through openings in the horizontal partitions 10 and partially condense on the surface of the coils 18 with the formation of additional reflux, which flows onto the plates 19 or additional plate 32 and evaporates from the surface of the liquid layer formed on them, and then flows onto the partitions 10. Where does the liquid through the hole enters the flanged washers 30 and then flows onto the underlying horizontal partition. At the exit from the upper side, the fortified pairs enter the reflux condenser 6 with the formation of reflux, and then to the condenser 7, from where the liquid is discharged in the form of distillate. The supply of cooling water to the coils 18 is carried out through the cold water pipe 24 to the throttling devices 21 and the heated water is discharged through the pipe 25. The heated water through the nozzle 26 is supplied to the reflux condenser 6.

The proposed distillation column in comparison with the known ones allows to increase the efficiency of the steps, reduce the dimensions of the column and increase its separation ability, which reduces capital and current costs, and therefore reduces the cost of the product.

Information sources

[1] Copyright certificate No. 190345, IPC ⁵ B01D and B01Y. Plate for contacting gas or steam with a liquid / Zhavoronkov N.M., Nikolaev N.A. - application No. 773280 / 23-5 from 09.4.1962. Publ. 12/29/66. BI No. 2.

[2] V.M. Ramm. Gas absorption. - M.: Chemistry, 1976 (p. 435 Fig. 5-18).

[3] Pat. RF №2152240, IPC B01D 3/26, B01D 3/30. Contact plate for vortex heat and mass transfer apparatuses / Halit R.A .: applicant and patent holder Halit R.A. - application No. 96112796/12 dated 06/18/1996. Publ. 07/10/2000.

Claims (7)

1. A distillation column, including a cube, a reflux condenser, a condenser, a housing with technological nozzles, consisting of casing, between which are placed horizontal partitions with openings and equipped with heat exchange devices made in the form of coils from pipe turns connected to the pipelines of the coolant system, in the lower part the horizontal partitions are equipped with contact nozzles, including a tangential swirl, a baffle device, a nozzle for draining fluid, an external cylinder and a water trap a cavity made of a cylindrical hydraulic shutter glass, characterized in that the heat exchangers are placed in the steam chamber of the casing under horizontal partitions and are equipped with at least one plate flanged from the ends, horizontally installed with a gap under the coil turns, and throttling devices are placed in the coils to maintain specified refrigerant flow, additional swirls with tangential channels are installed at the upper end of the cylindrical hydraulic shutter glasses, m the lower ends of the outer cylinder and the nozzle for draining the liquid are located below the channels for the passage of a pair of tangential swirls, while the ratio of the diameter of the swirl on which the tangential channels are placed to the diameter of the nozzle for draining the liquid is equal to D _s / D _p = 1.5-3 , 0. 2. The distillation column according to claim 1, characterized in that a beaded distribution washer is installed between the coil and the horizontal partition in the collets of the upper part of the column. 3. The distillation column according to claim 1 or 2, characterized in that the end of the pipe for the outlet of the coolant is connected by a pipe with a fitting for supplying refrigerant to the reflux condenser. 4. The distillation column according to claim 1, characterized in that the ratio of the cross-sectional area of the channels f for the passage of steam in the tangential swirler to the cross-sectional area of the channels f ₁ for the passage of steam of the subsequent higher swirler is maintained equal to f / f ₁ = 1.05-1, 25. 5. The distillation column according to claim 1, characterized in that the plate flanged from the ends is made with flanged holes, and the ratio of the flanging height of the ends of the plate h ₁ to the flanging height of the holes on it h is 0.8-0.99. 6. The distillation column according to claim 1, characterized in that at least one additional heat exchange device, for example, in the form of a coil equipped with an additional plate flanged from the ends, is placed in the steam chamber of the drawer. 7. The distillation column according to claim 1, characterized in that the surface of the heat exchanger is made in accordance with the dependence F = Q / (10 ² -10 ⁵ ) m ² , where Q is the heat expended in the condensation of the rising steam at the stages, W.

Images