RU2579084C2 - Contact interaction between gas and fluid and device to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention is meant for contact interaction between gas and fluid, particularly, for vapours cooling and condensation, chemical reactions, wet removal of whatever impurities from gases, absorption, distillation. Claimed process comprises the tangential gas feed to cylindrical casings (1), swirling of the gas flow about the casing axis to produce the helical vortex gas flow over the casing edges and feeding of fluid into said gas flow for fluid to be dispersed and heat exchange to occur between gas and fluid by their dynamic interaction. Said helical vortex gas flow at the cylindrical casing end is accelerated by contraction of said casing. Gas flow is turned to the casing axis to be missed with fed fluid. Said mix is directed to the centre of said helical vortex flow in the direction opposite the latter. Claimed device comprises tangential gas feed pipe (3), gas swirler (2), fluid feed pipe (4) at the bottom section of casing (1) in its axis and used phase discharge pipe (11) at top section of casing (1). Gas feed pipe (3) is arranged at the casing top section. Flask (5) with fluid is located under casing (1) and communicated with fluid feed pipe (4). The casing incorporates the extra baffle (9) arranged at the casing bottom section to turn the airflow at if transfer from periphery to the centre. This results in the contact interaction between gas and fluid in multiply vortex gas flow at counter stream both in crosswise and lengthwise cross-sections. Note here that fluid dispersion and heat exchange between media occur owing to mutual kinetic turbulence of plies of said vortex flow over its entire volume.

EFFECT: intensified heat exchange, higher process efficiency.

4 cl, 6 dwg

Description

Technical field

The invention relates to the field of chemical technology, heat engineering, more specifically to methods of contact interaction of media in gas-liquid, gas-liquid-solid particles systems and to devices for carrying out heat and mass transfer processes in the chemical, food, metallurgical, gas, gas processing, oil and other industries .

The invention is intended for cooling and condensation of vapors, chemical reactions, wet cleaning of gases from solid, liquid and gaseous impurities; absorption, distillation and other technological processes.

State of the art

From the document SU 1149475 a method of contact interaction of gas and liquid and a device for its implementation are known. The known method includes swirling a gas stream, feeding liquid into its axial zone, forming it into a film on the surface of the body of revolution, followed by dispersing the liquid with a swirling gas stream and separating it into a liquid and gas phase.

The disadvantages of this method and its implementing device are a low degree of dispersion of the liquid, insufficient contact area of the media due to the large diameter of the liquid droplets. With a decrease in gas flow rate, the diameter of the liquid droplets further increases, which reduces the efficiency of heat and mass transfer between gas and liquid.

A known method of contact interaction of gas, liquid and solid particles and a device for its implementation (vortex scrubber Venturi), described in the book Lukin V.D. et al. Purification of ventilation emissions in the chemical industry. - L .: Chemistry, 1980, p. 66-69. Dusty gas is tangentially fed into the confuser, which sucks liquid from the axial nozzle to wet the solid particles, form conglomerates and then separate them from the gas. The cleaning process is carried out in a vortex screw ring gas flow. A venturi scrubber is effective in capturing particles larger than 10 microns. With a smaller particle size, efficiency is reduced due to the low degree of dispersion of the liquid. To increase the degree of purification, two-stage purification is used, which complicates the process.

A known method of contact interaction of gas, liquid and solid particles and a device for its implementation according to the patent RU 2261139. According to the known method, not a gas is tangentially fed into a vortex scrubber, as in a Venturi scrubber, but a liquid absorber, which is twisted in a device in the form of a screw rotating water line cord. The dust and gas stream is fed along the axis of the scrubber to the reduced pressure zone. The fluid nozzle is axially movable relative to the device body. The tangential fluid supply is configured to change the direction of the swirl of the fluid and its flow depending on the parameters of the dust and gas flow, which is implemented using the control automation system. The known method improves the efficiency of the mass transfer process, however, it has the following disadvantages:

- insufficiently large contact area of the dust-gas mixture and the liquid absorber, since the liquid is concentrated mainly around the periphery of the device in the form of a screw "cord" and is not actively dispersed by the gas flow due to the low kinetic energy of the gas stream;

- a low degree of turbulization of gas and liquid flows, since the method uses a once-through system of their movement, which does not contribute to the formation of vortices and activation of the mass transfer process;

- increased pressure in the cleaning system of the dust and gas stream, since it is purged at the final stage through a container of water;

- the need to use additional equipment for automatic process control.

The closest in technical essence to the invention is a method of contacting gas and liquid and a device for its implementation according to patent RU 2192912. This method includes the following steps:

- tangential gas supply through a large number of nozzles,

- swirling the gas stream,

- the formation of an annular vortex flow with ensuring its movement along a helix,

- fluid supply to the reduced pressure zone along the flow axis,

- dispersing a liquid by a gas stream and forming it into a film,

- the implementation of mass transfer between gas and liquid in a vortex flow.

The features of this method are direct-flow contact of gas and liquid; the accumulation of liquid on the walls of the device and the formation of a rotating cylindrical layer through which gas jets are blown, after which the liquid is withdrawn and further dispersed by the gas stream. The formation of a cylindrical rotating liquid layer is carried out with centrifugal acceleration exceeding the acceleration of gravity up to 340 times.

A device for implementing the method comprises a housing, a gas flow swirl, tangentially mounted nozzles for supplying gas to the housing, a fluid supply pipe, an overflow baffle for forming a liquid layer on the walls of the housing, a liquid container and a pipe for withdrawing the spent phases. To press the gas flow to the surface of the liquid layer on the walls of the housing, the device is equipped with a cowl mounted along the axis of the device.

The known solution allows to increase the efficiency of mass transfer, that is, the contact of gas with a liquid, as well as expand the range of effective operation of the device.

However, the known method of contacting gas and liquid and a device for its implementation have the following disadvantages:

- a low degree of dispersion of the liquid, since the liquid in the mass transfer process is involved in the form of a layer on the walls of the device;

- undeveloped contact area of gas and liquid due to the formation of liquid in the form of a layer;

- slight turbulization of the gas flow due to the lack of countercurrent movement;

- short contact time of the reacting phases due to the low turbulization of gas and liquid flows and their direct-flow movement;

- increased pressure of the gas stream, as it is blown through a layer of liquid in the swirler;

- uneven distribution of gas and liquid flows over the cross section of the device and irrational use of the working volume due to the fact that the interacting phases are concentrated mainly on the periphery of the device, and the axial space is not involved in the mass transfer process.

As a result, the known solution does not allow for high efficiency mass transfer process.

The invention is aimed at improving the contact interaction of gas and liquid and the associated intensification of the mass transfer process between the phases and increasing its efficiency by increasing the degree of dispersion of the liquid, the contact area of the gas and liquid, turbulizing the gas flow, increasing the contact time, uniform distribution of gas and liquid over the cross section device and rational use of its working volume.

Disclosure of invention

The problem is solved in a method of contact interaction of gas and liquid, including the tangential gas supply to the cylindrical body, twisting the gas flow around the axis of the body with the formation of a helical vortex gas flow around the periphery of the said cylindrical body, supplying liquid to the vortex gas flow along the axis of the body with its dispersion gas flow and heat and mass transfer between gas and liquid due to their dynamic interaction. According to the invention, a helical vortex gas flow in the end part of a cylindrical casing is accelerated by narrowing the casing, the gas flow is turned to the axis of the casing, mixed with the supplied liquid and the gas-liquid flow is directed to the central region of the helical vortex flow in the opposite direction.

The problem is also solved in a device for the contact interaction of gas and liquid, including a cylindrical body, a tangentially mounted gas supply pipe, a gas swirl, a liquid supply pipe located in the lower part of the body along its axis, and a waste phase outlet pipe located in the upper body parts. According to the invention, a gas supply pipe is located in the upper part of the housing, and a container with a liquid is located under the housing, connected in a liquid medium to a liquid supply pipe, while the housing is further provided with a reflector located in the lower part of the housing and allowing air flow to rotate when it moves from the periphery to the center.

The method described above and the device implementing it, in comparison with the known solutions, can significantly improve the conditions of contact interaction of gas and liquid, intensify heat and mass transfer processes and increase their speed due to the following factors:

- the most developed area of contact between gas and liquid due to thin dispersion of the liquid;

- a high degree of dispersion of the liquid due to the high degree of mutual kinetic turbulization of the layers of the gas stream in longitudinal and cross sections throughout the volume of the working space;

- a significant increase in the contact time of gas and liquid due to the high turbulization of the gas flow, the formation of both counter longitudinal and transverse movement of gas and liquid and an increase in the residence time of the media in the device body.

These factors allow you to increase the productivity of the device due to the uniform distribution of the reacting phases over the cross section of the device casing, rational use of the entire working volume and activation of heat and mass transfer processes.

In addition, energy costs are reduced, since the processes of supplying a liquid to a gas stream, its dispersion, phase mixing and turbulence of the gas stream are carried out due to the kinetic energy of the gas without the use of additional energy costs.

Preferably, the surface of the reflector is the inner surface of the self-intersecting torus truncated by the equatorial plane, and the point of the torus surface of the reflector lying on its axis of rotation is preferably located below the equatorial plane at a distance of 0.75 ÷ 0.90 of the radius of the circumference of the torus surface.

Features and advantages of the invention will be more apparent from a further detailed description of an embodiment with reference to the drawings.

Brief Description of the Drawings

Figure 1 schematically shows a device for implementing the method of contact interaction of gas and liquid, a view in longitudinal section;

figure 2 is a section along aa in figure 1;

figure 3 presents a geometric model of the torus surface of the reflector;

figure 4 shows a diagram of gas dynamics in the working volume of the device for implementing the method of contact interaction of gas and liquid, a view in longitudinal section;

figure 5 is a section along bb in figure 4;

figure 6 is a section along CC in figure 4

An embodiment of the invention

The method of contact interaction of gas and liquid in accordance with the invention is implemented in the device shown in figures 1 and 2. This device contains a cylindrical housing 1 located in its upper part swirl 2 (for example, cochlear) and a tangentially mounted pipe 3 for supplying gas to the housing 1, a fluid supply pipe 4 mounted in the lower part of the housing in the zone of reduced pressure of the gas stream along its axis, a container 5 equipped with a pipe 6 for filling the tank, and a pipe 7 to provide a constant level liquids.

In the lower part of the housing 1 is mounted a partition wall 8. A reflector 9 is mounted on it, the surface of which is the inner surface 10 of the self-intersecting torus (Fig. 3), that is, a torus with a distance OO ₁ (or ОО ₂ ) between the axis X-X rotation and the center of the generating circle is less than the radius R _from this generating circle. The surface 10 is truncated by the equatorial plane 10 ′. The diameter d _o of the reflector, the diameter d _{of the} casing and the diameter d _m torus surfaces are equal. The point 10 ′ ′ of the torus surface of the reflector lying on its axis of rotation XX is located below the equatorial plane at a distance of 0.75 ÷ 0.90 of radius R _{from the} generatrix of the circle of the torus surface. To withdraw the spent phases from the device, there is a pipe 11 in its upper part, a gas and liquid separator 12, and a drain pipe 13. To remove residual liquid from the reflector, there are pipes 14. In the embodiment shown in the drawings, according to which the housing is essentially vertically, the nozzles 14 are located in the lower part of the surface 10 of the fairing reflector 9, however, they can be located in other places, in particular in the side surface of the housing with its location other than vertical.

It should be noted that the terms “upper” and “lower” in this description are used in relation to the structure schematically shown in figures 1 and 4, that is, they are conditional, and essentially mean that some elements (swirl 2, pipe 3 gas supply, pipe 11 output of the spent phases) are located on one base of the cylindrical body, and others (dividing wall 8, the capacity 5 for liquid and pipes 6 and 7) - on the other.

The method of contact interaction of gas and liquid in accordance with the invention is as follows (figure 4 ÷ 6). A gas is tangentially fed into the device housing 1, which is twisted by a swirl 2 to form a helical vortex flow concentrating along the walls of the housing and moving at a high speed along the helix L in the form of a helical “cord”. At the same time, the gas flow in the screw “cord” rotates around the axis along the helix F. Then the vortex ring gas flow enters the lower part of the device’s body, where it is accelerated due to the narrowing of the body through the torus surface 10 of the reflector 9, deviates from the initial direction, and makes a turn to the axis of the housing, mixes with the supplied fluid and enters the central region of the helical vortex flow in the opposite direction.

The flow velocity and its kinetic energy in this case significantly increase due to a decrease in its diameter.

As a result of the rotation of the gas flow in the casing, a multilayer (four-layer) vortex flow is formed in which countercurrent motion of the layers is observed both in the transverse and longitudinal sections. The longitudinal and transverse boundaries of the Q layers, due to oncoming motion and high flow rates, cause intense mutual, kinetic turbulization of the first surface sections and then the inner zones of the layers, which ultimately leads to gas turbulization throughout the entire volume V of the stream and body. A low pressure zone is formed along the S axis of the housing as a result of the high flow rate, due to which liquid from the nozzle 4 is ejected into the stream. The amount of liquid entering the gas stream automatically changes with a change in the gas flow rate, that is, with a change in gas flow.

The liquid entering the gas stream is actively dispersed and finely atomized by the turbulized gas stream. Liquid particles are evenly distributed over the entire volume of the stream, mixed with the vortices of the stream and react with the gas, while ensuring the highest possible heat or mass transfer coefficient.

The above relations between the structural parameters of the device for implementing the method of contact interaction of gas and liquid are optimal. By observing the ratios, high heat and mass transfer processes are achieved.

So, when the point 10 ″ of the torus surface is located by an amount less than 0.75 of radius R _{from the} circumference of the torus surface 10, a rarefaction zone is formed in the central axial part of the flow, in which the ascending layers of gas do not intersect and do not contact each other, which reduces the possibility of turbulization due to kinetic interaction and reduces the efficiency of the mass transfer process. In this case, an excess amount of liquid is also trapped by the flow from the pipe 4.

When the point 10 ′ ′ of the torus surface 10 is located at a value of more than 0.90 radius R _{from the} circumference of the torus surface 10, the gas flows intersect with each other, break down and disrupt surface contact in the central and upper parts of the device, which reduces the kinetic turbulence of the gas flow and efficiency mass transfer. In addition, the conditions of ejection of the liquid into the gas stream are worsened, and the amount of liquid becomes insufficient for the process of mass transfer.

Claims (4)

1. The method of contact interaction of gas and liquid, including the tangential gas supply to the cylindrical body, swirling the gas flow around the axis of the body with the formation of a helical vortex gas flow around the periphery of the said cylindrical body, supplying liquid to the vortex gas flow along the axis of the body to ensure its dispersion by the gas stream and heat and mass transfer between gas and liquid due to their dynamic interaction, characterized in that the helical vortex gas flow in the end of the cylindrical body accelerate by narrowing the said housing, deploy the gas flow to the axis of the housing, mix with the supplied liquid and direct the gas-liquid flow into the central region of the helical vortex flow in the opposite direction. 2. A device for the contact interaction of gas and liquid, including a cylindrical body, a tangentially mounted gas supply pipe, a gas swirl, a liquid supply pipe located in the lower part of the body along its axis, and an exhaust phase outlet pipe located in the upper part of the body, characterized in that the gas supply pipe is located in the upper part of the housing, and a container with liquid is located under the housing, connected in a liquid medium to the liquid supply pipe, while the housing is further provided with a reflection a body located in the lower part of the housing and providing rotation of the air flow during its movement from the periphery to the center. 3. The device according to claim 2, characterized in that the reflector surface is the inner surface of a self-intersecting torus truncated by the equatorial plane. 4. Device according to claim 3, characterized in that the point of torus reflector surface lying on its axis of rotation is located below the equatorial plane at a distance of 0.75 ÷ 0.90 radius (R _on) of the generatrix circle torus surface.

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