RU2797870C1 - Vortex type contact device - Google Patents

Abstract

FIELD: exchangers.

SUBSTANCE: contact devices for multi-stage heat-mass-exchange apparatus for rectification, distillation, absorption, desorption, extraction. The vortex contact device includes a cylindrical contact pipe fixed on the web, provided with an external cylinder located coaxially to the contact pipe, a device for draining liquid from the web, a fender. From the outside, the outer cylinder is surrounded by a jacket with branch pipes for supplying and discharging the intermediate coolant. The jacket diameter is from 1.05 to 1.1 of the outer cylinder diameter.

EFFECT: ensuring high intensification of heat and mass transfer processes by increasing the contact surface of the media through the separating heat transfer wall of the jacket.

1 cl, 2 dwg

Description

The invention relates to contact devices for multi-stage heat and mass transfer apparatus for distillation, distillation, absorption, desorption, extraction and can be used in biotechnology, chemical, oil refining and other industries.

There are various contact devices of heat and mass transfer apparatus operating in the gas-liquid system, the interaction of the phases in which is carried out in a swirling flow. They include contact nozzles installed on the plate web, equipped with swirlers, liquid and gas inlet and outlet units.

So in the mass transfer apparatus [A.S. USSR SU 498009, B01D 3/26, B01D 3/30, 1974] the plate is made in the form of a sheet on which the contact pipe is tightly fixed, equipped in the lower part with a multi-blade swirler and a fluid supply unit to the contact zone from the overlying plate, and in the upper part - with a fender in the form of a cap for phase separation. The liquid supply unit is made in the form of a U-shaped tube, one end of which is fixed in the overlying stage canvas, and the other end is in the center of the contact pipe above the swirler, plugged from above and provided with holes on the side surface. Such a constructive solution, according to the authors, contributes to the expansion of the stable operation of the apparatus, reduces inter-tray entrainment and improves mass transfer.

However, this plate is characterized by a small time and phase contact surface, as well as secondary entrainment of liquid droplets from under the separation cap, which significantly reduces heat and mass transfer, especially at high loads in the liquid phase.

A contact device for heat, mass transfer and separation processes is known, including a contact cylindrical pipe, vertically rigidly mounted on a support web, made with a hole for gas supply, a contact cylindrical pipe equipped with a means for supplying liquid and made with holes - from below for gas supply, from above for its exit, a film liquid remover is installed in the upper part of the contact pipe, a static bladed swirler is installed in the contact pipe coaxially with it [patent RU 2647312, B01D 3/30, B01D 45/14, 2017]. The swirler is made multi-blade, the swirler inlet is located in the lower part of the contact pipe, the swirler blades are each made in the form of an elongated plate and fan-shaped at an acute angle to the axis of the contact pipe with partial overlap on adjacent plates, the outer side edges of the blades form a conical surface of the swirler oriented with a large base up, the inner edges of each blade are made with the formation of slotted gaps between adjacent blades, the height of the swirler cone is 1.2-1.4 times greater than the inner diameter of the contact pipe, the total flow area of the slotted gaps between the blades of the conical swirler is 0.9-1.1 internal section of the contact pipe, the means for supplying the flushing liquid is located below the swirler.

The disadvantages are the complexity of the design and the low efficiency of heat and mass transfer at high loads in the liquid phase due to flooding of the device.

A contact device for a heat and mass transfer apparatus is known [patent RU 2780517, IPC B01D 3/30, 2022], including a cylindrical pipe, vertically rigidly mounted on a support web, made with a hole for supplying gas (steam). The branch pipe is equipped with a perforated cover for liquid distribution. The lower part of the branch pipe has openings for draining the liquid evenly spaced around the circumference, above which, up to the upper edge of the branch pipe, at least eight vertical slot-like slots of a rectangular shape are cut out, and the total cross-sectional area of the slot-like slots is equal to the area of the internal diameter of the branch pipe. The ratio of the nozzle height to its inner diameter is from 1.0 to 1.5.

The disadvantage of analogue is the ingress of vapors (gases) into the annular space between the pipe and the body of the heat and mass exchange apparatus through the holes for draining the liquid, as well as the re-entrainment of liquid drops from this space.

As a prototype, a contact plate for vortex heat and mass transfer devices was chosen [patent RU 2152240, IPC B01D 3/26, B01D 3/30, 1996], consisting of a canvas on which a contact pipe is installed with a swirler in the lower part and a bump stop above it, which is equipped with inner and outer cylinders and is located coaxially to the contact pipe. The web is provided with nodes for supplying and discharging liquid from the tray web and for supplying liquid to the swirler. The inner cylinder is made with a blind base to form a cavity in which the liquid phase supply pipe is placed. The lower section of the outer cylinder is made with a flange located with a gap to the wall of the apparatus and the web to form a pocket, and the cavity of this pocket is in communication with the fluid supply unit to the swirler.

The disadvantage of the prototype is a small phase contact surface, since the interaction of the gas occurs only with the flowing liquid on the stage, which is not effective enough and as a result leads to an increase in the number of plates, thereby increasing the metal content of the heat and mass transfer column.

The technical problem is the development of a vortex-type contact device, in which the disadvantages of the prototype and analogue are eliminated.

The technical result is achieved by a vortex-type contact device, which includes a cylindrical contact pipe fixed on the web, equipped with an external cylinder located coaxially to the contact pipe, a device for draining liquid from the web, a fender. From the outside, the outer cylinder is surrounded by a jacket with branch pipes for supplying and removing the intermediate coolant. The jacket diameter is from 1.05 to 1.1 of the outer diameter of the outer cylinder.

The technical result is to provide high intensification of heat and mass transfer processes by increasing the contact surface of the media through the separating heat transfer wall of the jacket, which makes it possible to increase the efficiency of heat and mass transfer processes while simplifying the design and reducing the metal consumption of the contact device.

The essence of the invention is illustrated by drawings:

- in Fig. 1 shows a longitudinal section of a variant of the layout of the heat and mass transfer apparatus with the proposed contact device of the vortex type;

- in Fig. 2 is its cross section A-A in FIG. 1.

The contact device of the vortex type (see Fig. 1, 2) includes a canvas 1, a cylindrical contact pipe 2, an external cylinder 3 located coaxially to the contact pipe 2, a device 4 for draining liquid from the canvas 1, a fender 5. From the outside, the outer cylinder 3 is surrounded by a jacket 6 with a supply pipe 7 and an intermediate coolant outlet pipe 8. Jacket 6 is a sealed volume adjacent to the outer wall of the outer cylinder 3 along the entire height, in which there is an intermediate coolant (in a particular case, recycled water). The diameter of the jacket 6 is from 1.05 to 1.1 of the outer diameter of the outer cylinder 3, due to the increased speed of the intermediate heat carrier and the achievement of high heat transfer coefficients. An increase in the diameter of the jacket 6 from the specified range leads to an increase in resistance, and a decrease leads to insufficient maintenance of the temperature of the intermediate coolant.

Above the device 4 for draining liquid from the web 1, the contact pipe 2 has vertical rectangular slots 9 uniformly cut along the circumference to the upper edge of the pipe 2 for the passage of gas (steam), the total area of which is equal to the area of the inner diameter of the contact pipe 2 (see Fig. 2) . Moreover, the device 4 for draining liquid is a uniformly spaced around the circumference of square holes in the lower part of the pipe 2 to ensure continuous drainage of liquid from the sheet 1, the number of which coincides with the number of slots 9. The support sheet 1 has a water seal 10, which prevents vapors (gases) from entering the annular space between the branch pipe 2 and the outer cylinder 3 through the holes for draining the liquid. All this expands the range of effective stable operation of the contact device, especially at high liquid phase flow rates.

With a multi-stage layout of the heat and mass transfer apparatus, vortex-type contact devices are installed over the entire height at a distance from each other in the amount necessary for the implementation of the process, forming a separation zone between the fender 5 of the underlying contact device and the web 1 of the overlying contact device, where the flowing liquid is broken up by an ascending gas flow ( steam) into individual jets and drops.

The contact device of the vortex type works as follows. Gas (steam) moves from the bottom up and enters the contact pipe 2 through the central hole made in the web 1. Then it moves through rectangular slots 9, accelerating sharply and splitting into two vortices rotating in opposite directions. Thus, in the annular space between the contact pipe 2 and the outer cylinder 3, a stable vortex motion is formed over the entire height.

The liquid enters the contact device from above to the fender 5, colliding with its surface, breaks up into drops, and is also redistributed in the form of a film down the walls of the annular space between the contact pipe 2 and the outer cylinder 3, where it meets with an ascending swirling flow of gas (vapor) . Thus, from the flowing liquid film along the walls of the annular space between the contact pipe 2 and the outer cylinder 3, under the action of gas (steam), separate drops and jets of liquid break off, thus forming a gas-(vapor)-liquid swirling flow over the entire height, which is characterized by a constant renewing phase contact surface, high coefficients of heat and mass transfer, which contribute to an increase in the efficiency of the contact device. Further, the main part of the disintegrated liquid under the action of centrifugal forces is thrown to the wall of the outer cylinder 3, where a film flow is created. In this case, the liquid, reaching the slots 9, partially enters the contact pipe 2, where it also interacts with the upward flow of gas (steam). The other part of the liquid passes through the holes for draining the liquid and is discharged from the contact device 2, meeting on its way along the supporting canvas 1 a hydraulic seal 10, which prevents vapors (gases) from entering the annular space between the pipe 2 and the outer cylinder 3 through the holes for draining the liquid. The distance between the canvas 1 and the upper part of the rectangular holes for draining the liquid is equal to the height of the liquid layer on the canvas 1.

Overflowing through the hydraulic seal 10, the liquid flows down to the fender 5 of the underlying contact device, meets in the separation zone with ascending vapors that have escaped from the annular space between the contact pipe 2 and the outer cylinder 3 of the underlying contact device, where the gas is separated from the liquid under the action of centrifugal and gravitational forces. The separated gas (steam) flow is directed from bottom to top into the cylindrical branch pipe 2 of the overlying contact device. Also, to increase the heat exchange surface, an intermediate coolant is supplied to the shirt 6 through the pipe 7, which enters from below and is discharged from the top through the pipe 8. Due to the cooling of the gas-liquid flow when passing through the wall separating the shirt 6 from the annular gap between the outer cylinder 3 and the pipe 2, the processes are significantly intensified heat and mass transfer. At the same time, due to the swirling gas-liquid flow, the phase contact surface is constantly updated, and the phase contact time increases. High specific heat fluxes through the outer cylinder 3 allow the most efficient transfer of heat to the coolant in the jacket 6 during vapor condensation in the annulus.

The proposed contact device of the vortex type provides the formation of a swirling flow of gas (vapor) and liquid drops in the vertical channel of the proposed device, which forms a high intensity of mixing in the cross section of the device, increasing the efficiency of heat and mass transfer. At the same time, the numerical studies performed show that on the inner wall of the outer cylinder in the region of swirling flows, the values of heat transfer coefficients equal to 14747 W/(m ² ⋅K) are achieved at an average fluid flow rate of 1 m/s. Thus, the creation of conditions for increasing the speeds of movement of the contacting phases relative to each other and the continuous renewal of the interfacial surface, including due to the presence of a jacket, contributes to an increase in the thermal efficiency of the contact device. The presence of a hydraulic seal eliminates the possibility of gas phase slippage, which expands the range of effective operation of the device, especially at high liquid phase flow rates and low gas load. The simplicity of the design of the contact device makes it possible to reduce the volume and weight of the heat and mass transfer apparatus.

The proposed contact device of the vortex type ensures the intensification of heat and mass transfer processes by increasing the contact surface of the media through the separating heat transfer wall of the jacket, which makes it possible to increase the efficiency of heat and mass transfer processes. The device has a simple design and can be used in heat and mass transfer apparatus for the processes of distillation, distillation, absorption, desorption, extraction.

Claims (5)

A vortex-type contact device, comprising: - a cylindrical contact pipe fixed on the web, equipped with an external cylinder located coaxially to the contact pipe, - a device for draining liquid from the web, - breaking device characterized in that the cylindrical contact pipe contains vertical slots of a rectangular shape, and on the outside the outer cylinder is surrounded by a jacket with pipes for supplying and removing the intermediate heat carrier, and the jacket diameter is from 1.05 to 1.1 of the diameter of the outer cylinder.

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