RU2466767C2 - Heat-and-mass exchange vortex column - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed column comprises still section, cover, vertical body composed of shell sections and trays with horizontal webs alternating over their height. Top trays have central overflow and outer drain barrels while bottom trays are provided with outer overflow barrel and drain branch pipe. Tray horizontal webs accommodate vapor (gas) swirlers comprising different-diameter spaced apart distribution discs with extra tangential shaped plates arranged on their surface to make vapor passages. Relation between distances H_i and L_i from top edges of drain branch pipe and outer drain barrel to the surface of distribution disc and radial distance between distribution discs δ is kept equal to H_i/δ = L_i/δ = 1.25-10. Relation between radius R_"б" of circle whereon seat outlets of shaped discs and radius R_K of circle crossing the center of perpendicular connecting two shaped plates in the least cross-section of vapor (gas) passage for top tray makes R_"б"/R_K= 0.8-0.96 and for bottom plate it equals R_K/R_"б" = 0.8-0.96.

EFFECT: higher efficiency

4 cl, 7 dwg

Description

The invention relates to heat and mass transfer apparatus for carrying out the processes of rectification, absorption, extraction, in particular, the column can be used as a strengthening fluid in the processing of large flows in biotechnology, chemical, oil refining and other industries.

A known plate for contacting gas or vapor with a liquid [1], including a horizontal partition on which are mounted the body of the contact device and the glass of the hydraulic seal. The upper part of the housing of the contact device is made with tangentially directed holes and is provided with a lid with a steam pipe passed through it, and the lower part of the housing ends with a drain pipe lowered into the hydraulic seal cup of the underlying horizontal partition.

However, this plate has low mass transfer efficiency, large dimensions and metal consumption, and the presence of stagnant zones on the plate contributes to the rapid accumulation of deposits on the surface of the horizontal partition during the processing of industrial mixtures that form sediment.

The low mass transfer efficiency is due to the small size of the interfacial surface, since not all liquid at the stage is dispersed by the vapor (gas) stream when it exits from tangentially directed holes (devices for swirling the flow) due to the presence of stagnant zones in the liquid between contact devices placed on a horizontal the partition, and the plate body, which also leads to the formation of sediment in stagnant zones on the surface of the plate and reduce the duration of its operation. The high metal consumption of the plate is due to the complex design of the contact devices.

The closest in technical essence is the mass transfer column [2], consisting of a vertically mounted housing, the height of which in an alternating order are plates; the upper plates are equipped with a central overflow cup and an external drain cup, and the lower plates are equipped with an external overflow cup and a drain pipe, which form hydraulic locks, and on the plates in the radial direction there are profiled plates oriented in the plane of the plate, performing the functions of a device for swirling the flow of steam (gas) )

However, this device also does not have a sufficiently high mass transfer efficiency, low productivity for steam (gas), and has zones in the liquid that are not dispersed by steam.

The considered design of the column, namely, its device for swirling steam (gas), has several disadvantages caused by the radial placement of profiled plates on the plates, which leads to the implementation of channels for the passage of steam with a small gap and a long length, and this leads to their rapid clogging by deposits and short work of the column. In addition, it is difficult to ensure uniform flow of steam through the channels on the periphery of the plate and in its central part due to the formation of a cavity in the center of the plate (partial exposure of the channels occurs) caused by centrifugal force during rotation of the gas-liquid mixture, which reduces the contact of the vapor with the liquid.

The implementation of the channels of small length does not allow for the rotation of the entire gas-liquid mixture on the plate (as studies have shown, only the liquid layer that is located above the channels rotates), which, of course, reduces the efficiency of mass transfer. The small size of the channel gap follows from the need to fulfill the required ratio of the volumetric flows of steam and liquid, justified by technological calculations. In this regard, for industrial implementation on plates it is preferable to install devices for twisting tangential type steam.

Thus, the low efficiency of the mass transfer column is caused by an insufficient phase contact surface due to the formation of a cavity in the center of the plate, which leads to partial exposure of the channels for steam passage, and the presence of unaerated zones on the plates, namely in the gaps between the central overflow nozzle and the drain pipe and between the inner drain cup and internal overflow cup. The presence of the cavity is due to the action of centrifugal force, which presses the rotating gas-liquid layer on the plate to the periphery of the column, which is especially noticeable with increasing steam flow, in this regard, the operation of the column is possible only in a narrow range of steam (gas) flow. In addition, the presence of unaerated zones leads to the deposition of particles from the liquid on the surface of the plates, which reduces the duration of the column.

The invention solves the problem of increasing the efficiency of mass transfer, productivity of steam (gas) and the duration of the column, reducing unaerated stagnant zones and improving the dispersion of steam in the liquid on the plates.

The technical result consists in increasing the efficiency of mass transfer, steam (gas) productivity and the duration of the column by increasing the interfacial contact surface, reducing unaerated stagnant zones and improving the dispersion conditions of the vapor in the liquid on the plates by providing a more complete contact of the vapor with the liquid.

The specified technical result is achieved by the fact that the heat and mass transfer vortex column, including a still part, a cover, a vertical body made of tsar, the height of which are arranged in horizontal order in the horizontal partitions of the plates; the upper plates are equipped with a central overflow cup and an external drain cup, and the lower plates are equipped with an external overflow cup and a drain pipe; devices for twisting steam (gas) are placed on the horizontal partitions of the plates, consisting of tangentially mounted profiled plates closed by a lid with the formation of channels for the passage of steam (gas); in devices for twisting steam (gas) between the horizontal partition and the lid, distribution discs of different diameters are installed with a gap relative to each other, on the surface of which additional shaped plates are tangentially placed with the formation of channels for the passage of steam; the ratio of the distances H _i and L _i from the upper ends of the drain pipe and the external drain cup to the surface of the installed distribution disc on the plate to the radial distance between the distribution discs δ is maintained equal to H _i / δ = L _i / δ = 1.25-10, moreover, the ratio of the radius of the circle R _b , on which the output ends of the perforated plates are located, to the radius R _{to the} circle passing through the middle of the perpendicular drawn between the two plates in the smallest section of the channel for the passage of steam (gas) R _k , for the upper th plate is equal to R _b / R _k = 0.8-0.96 and for the lower plate R _k / R _b = 0.8-0.96, and the ratio of the total area f of the channels for the passage of steam on any of the distribution discs in their the smallest cross-section to the area of the lateral cylindrical surface F of radius R _k on which these smallest cross-sections are located is made in accordance with f / F = 0.05-0.5; the side surfaces of the distribution discs are made on a cone with an angle of inclination to the axis of the column equal to 20-60 degrees; the lower ends of the outer drain cups are equipped with a conical flanging, tapering to the axis of the column; the upper ends of the drain pipes are equipped with a conical flange, expanding to the column body.

The placement between the horizontal partition and the cover with a gap relative to each other distribution discs of different diameters, on the surface of which are additionally profiled plates tangentially placed forming channels for the passage of steam, ensuring the ratio of the distances H _i and L _i from the upper ends of the drain pipe and the external drain cup to the surface distributing disc mounted on a plate to a radial distance between the distributing disc δ equal to _{H i / δ = L i /} δ = 1,25-10, as well as providing otno eniya R _b circumferential radius on which are placed the outlet ends of the perforated plates, and the radius of the circle passing through the middle of the perpendicular drawn between two profiled plates in the smallest section of the duct for steam passage (gas) R _k for the upper plate equal to R _b / R _a = 0.8-0.96 and for the lower plate - R _k / R _b = 0.8-0.96, as well as observing the ratio of the total channel area on any of the distribution discs in their smallest section f to the side cylindrical surface F of radius R _k, which has the smallest section, in a ratio f / F = 0,05-0,5 can increase the efficiency of the column, a pair of performance (gas) and the duration of its operation.

The installation between the horizontal partition and the lid with a gap relative to each other of distribution discs of different diameters, on the surface of which additional shaped plates are formed tangentially, forming channels for the passage of steam, allows for dispersion of the vapor in the liquid over the entire cross section of the column (in a wide range of variation of the diameter of the column) and thereby eliminating stagnant (not vapor dispersed) zones in the liquid on the plates, preventing the steam from spilling over onto the overlying plate and increasing m zhfaznuyu surface. Which leads to an increase in the efficiency of mass transfer, steam production and duration of work. (That is, each distribution disk, with profiled plates placed on it, provides dispersion of a certain layer of liquid on the plate, therefore, if the number of distribution disks on the plate required by the technology is achieved, liquid dispersion is achieved over the entire cross section of the column).

Fulfillment of the relationship of the distances H _i and L _i from the upper ends of the drain pipe and the external drain cup to the surface of the distribution disc mounted on the plate to the radial distance δ between the distribution discs equal to H _i / δ = L _i / δ = 1.25-10 (under the set a distribution disk is understood to mean any distribution disk considered) allows efficient dispersion of steam in a fluid in a radial direction by a distance δ and thereby eliminates stagnant zones (zones not dispersed by a liquid).

The distance H _i and L _i is the height of the gas-liquid layer above the distribution disk of the lower or upper plate, and the value δ is equal to the difference of the radii of the distribution disks (R _i -R _j ) (for the presented figure 3 these are the radii R ₂ and R ₁ ). When the relations H _i / δ = L _i / δ <1.25, the liquid column above the distribution disk (hydrostatic pressure) is not enough to hold the jet and ensure its movement in the radial direction. Therefore, in this case, the steam flow rises upward, and not in the radial direction, which reduces the dispersion efficiency of the liquid, and therefore reduces the interfacial surface and the efficiency of the plate.

When the ratio H _i / δ = L _i / δ> 10 is fulfilled, the effective rotation of the liquid above the distribution disk is not ensured, the fragmentation of the vapor bubbles and the interfacial surface are reduced. Which also leads to the formation of stagnant zones and reduced performance of the column.

Fulfillment of the ratio of the radius of the circle on which the output ends of the perforated plates R _b are located to the radius of the circle passing through the middle of the perpendicular (length s see FIG. 4) drawn between two profiled plates in the smallest section of the channel for the passage of steam (gas) R _to , for the upper plate equal to R _b / R _k = 0.8-0.96 and for the lower plate - R _k / R _b = 0.8-0.96, provides the steam flow in the tangential direction, thereby causing intense rotational movement of gas-liquid mixture on a plate, effective crushing ue bubbles, high interfacial surface and thus increases the efficiency of mass transfer.

When the ratios R _b / R _to and R _to / R _b less than 0.8 are not achieved, the placement of profiled plates, providing intensive rotation of the liquid.

When the ratios R _b / R _to and R _to / R _{b are} more than 0.96, the constructive design of devices for twisting steam (gas) is difficult due to the presence of a large number of perforated plates, which is also ineffective.

Ensuring the ratio of the total area of the channels on any of the distribution discs in their smallest cross-section f to the lateral cylindrical surface F of radius R _k , on which these smallest cross-sections are placed, equal to f / F = 0.05-0.5, makes it possible to provide a contact surface with liquid sufficient to create a rotational motion of the gas-liquid layer on the plates, and this, in turn, provides an increase in mass transfer efficiency. Moreover, the surface F is calculated according to the well-known formula F = h 2π R _k , where h is the height of the channel (figure 3).

When the ratio f / F <0.05 is fulfilled, the necessary contact surface of the steam jets with the liquid is not provided and, therefore, the rotation of the liquid on the plates is not achieved, which is inefficient.

When the ratio f / F> 0.5 is fulfilled, the design of the plates is complicated.

The implementation of the side surfaces of the distribution discs in the device for twisting the steam flow on a cone with an angle of 20-60 degrees to the axis of the column increases the efficiency of the plates and increases the duration of their work. The increase in efficiency is due to the fact that the residence time of steam in the liquid leaving the channels of any distribution disk is approximately the same due to the same value of H _i and L _i (liquid column) for all distribution disks. The increase in the duration of operation is due to a decrease in the formation of deposits on the surface of the distribution discs during a forced stop of the column due to liquid draining along with impurities along the inclined (conical) surface of the distribution discs from the plate.

Performing a taper angle of the surface of the distribution disc of less than 20 degrees or more than 60 degrees leads to unjustified complication of the design of the plates without an adequate increase in efficiency.

The presence at the lower end of the outer drain cup of a conical flanging, tapering to the axis of the column, provides a more intensive rotation of the fluid due to the appearance of additional force (projection of the inertia force on the generatrix of the cone) and, therefore, a large interfacial surface.

Installing a conical flange at the upper end of the drain pipe, expanding to the column body, increases its productivity by increasing the perimeter of the fluid drain, which increases the working load range for a couple.

Placing distribution discs of different diameters in the devices for swirling the flow of steam (gas) and installing additional profiled plates on them, as well as the optimal design ratios of the plate elements, eliminate steam leakage through the bare channels and remove stagnant zones (not dispersed by steam) in the liquid on the plates in columns of different diameters in a wide range of changes in steam flow.

With the proposed structural design, the steam leaving the channels formed by the profiled plates on the distribution disk of a certain diameter disperses the liquid column on the plate by a value of δ in the radial direction, provides its rotation and increase the mass transfer efficiency due to the developed interfacial surface. Installing a certain number of distribution discs on a plate allows you to create a rotating gas-liquid layer over the entire cross section of the column. This also eliminates the breakthrough of steam (without contact with the liquid) on the plate with relatively large loads of steam. In addition, the dispersion of steam throughout the volume of liquid on the plates eliminates the formation of stagnant zones, which prevents the accumulation of sediment on the surface of the devices and increases the duration of the column.

Figure 1 presents a General view of the heat and mass transfer vortex columns.

Figure 2 presents the king of the heat and mass transfer vortex columns.

Figure 3 presents a device for swirling steam (gas).

Figure 4 presents a section of the column along section AA of the lower plate.

Figure 5 presents a section of the column along section BB of the upper plate.

Figure 6 presents the distribution disk with profiled plates.

Figure 7 presents the casing of a heat and mass transfer vortex column with distribution discs made on a cone.

The heat and mass transfer vortex column consists of a cubic part 1, a cover 2, a vertical casing 3 made of tsar 4, the heights of which are arranged in alternating order horizontal partitions 5 of the upper plates, equipped with a central overflow 6 and external drain 7 glasses and horizontal partitions 8 of the lower plates, equipped with an external overflow cup 9 and a drain pipe 10. On the horizontal partitions 5 and 8 there are devices for twisting the steam stream 11, consisting of covers 12 and distribution discs 13 different diameter, installed with a gap relative to each other. On the distribution discs 13, on one side, profiled plates 14 are tangentially mounted and, on the other hand, additional plates 15. The profiled plates 14 and 15 form channels 16 for the passage of steam and for the rotational movement of steam (gas). Distribution discs 13 can be made on a cone with an angle of 20-60 degrees to the axis of the column (Fig.7). The lower end of the outer drain Cup 7 is equipped with a flange 17, directed to the axis of the column. The upper end of the drain pipe 10 is equipped with a flange 18, directed towards the column body. The column is also equipped with separation devices 19, a support 20 and a system of technological fittings and bosses 21, 22, 23.

The geometric parameters of the device for swirling steam (gas). The radius R _{b of the} circle on which the output ends of the profiled plates 15 are placed is 0.05-3 m. The height H _i and L _{i is} 0.01-0.4 m. The cross-sectional area of the output channels placed on the distribution disk is calculated according to the known dependences f = G _p / u, where G _p is the volumetric flow rate of steam entering the channels of the distribution disk under consideration, u = 4-80 m / s is the steam velocity in the channel during the rotational movement of the gas-liquid layer on the plate.

Heat and mass transfer vortex column operates as follows. The working fluid through the nozzle 22 enters the column and along the annular gap formed by the column body and the external drain cup 7, enters the lower plate of the upper drawer, comes into contact with steam (gas), and then flows through the drain pipe 10 onto the upper plate of the lower drawer where steam is also in contact with the liquid. After passing through all the plates of the column, the liquid enters the still bottom part 1 of the column. Steam (gas) enters the bottom of the column through the nozzle 21, passes into the channels 16 formed by profiled plates 14 and 15, acquires a rotational movement, and then disperses in the form of jets into a liquid placed on a plate, providing rotation of the gas-liquid mixture. Due to which, the vapor bubbles are crushed and a large phase contact surface is created. Then the vapor (gas) from the lower plate rises due to the pressure difference created in the still bottom part 1 and a water seal in the annular gap between the housing of the drawer and the external drain cup 7, and enters the channels 16 of the device for swirling the steam stream 11 of the overlying plate, disperses in fluid plates. Since the distribution discs have different diameters with respect to the inner diameter of the column, this ensures complete dispersion of all the liquid placed on the plate, without the formation of stagnant zones. In the upper part of the column, steam enters the separation devices 19, equipped with devices for swirling the flow, is separated from the liquid droplets and removed from the column, and the liquid droplets are returned to the plate.

The use of the inventive heat and mass transfer vortex column allows to increase its efficiency, productivity and duration of work, which reduces capital and current costs, and therefore the cost of the product.

Information sources

1. A plate for contacting gas or steam with a liquid. SU 190345, IPC B01j, B01d, publ. 12/29/1966, bull. No. 2 dated 11.2.1967.

2. Mass transfer column. SU No. 439297, IPC B01d 3/30, publ. 08/15/74, bull. No. 30 dated 01/22/1975.

Claims (4)

1. Heat and mass transfer vortex column, including a still part, a lid, a vertical casing made of tsar, the height of which is arranged in alternating order horizontal plate partitions; the upper plates are equipped with a central overflow and an external drain cups, and the lower plates are equipped with an external overflow cup and a drain pipe; devices for spinning steam (gas) equipped with a lid are installed on the horizontal partitions of the plates; in devices for swirling the flow of steam (gas), distribution discs of different diameters are installed with a gap relative to each other, on the surface of which additional profiled plates are tangentially placed to form channels for the passage of steam (gas), while the distribution discs are located between horizontal partitions and covers, and ratio of distances H and _i L _i from the upper ends of the spout and the external downcomer to the surface of the distributor disc mounted on the plate to the radially Distance y between the distributing disks is kept equal to δ _{H i / δ = L i /} δ = 1,25-10, wherein the ratio of the radius R _b of the circle on which are located the outlet ends of profiled plates _to the radius R of the circle passing through the middle of the perpendicular held between two profiled plates in the smallest section of the channel for the passage of steam (gas) for the upper plate equal to R _b / R _a = 0,8-0,96 and lower plates - R _a / R _b = 0,8-0, 96; and the ratio of the total area f of the channels for the passage of steam in their smallest section, placed on any of the distribution discs, to the area of the lateral cylindrical surface F of radius R _to where these smallest sections are placed, is made in accordance with f / F = 0.05-0 ,5. 2. Heat and mass transfer vortex column according to claim 1, characterized in that the side surfaces of the distribution discs are made on a cone with an angle of inclination to the axis of the column equal to 20-60 °. 3. Heat and mass transfer vortex column according to claim 1, characterized in that the lower ends of the external drain cups are equipped with a conical flanging, tapering to the axis of the column. 4. Heat and mass transfer vortex column according to claim 1, characterized in that the upper ends of the drain pipes are equipped with a conical flange, expanding to the body of the column.

Images