RU2502929C1 - Heat and mass exchange vortex-type device - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: heat and mass exchange vortex-type device includes a cylindrical housing, a cover with a spraying centrifugal atomiser and a non-condensed gas removal branch pipe, and a bottom with a condensate removal branch pipe. A regular perforated head piece is coaxially installed inside the housing and represents a hollow flattened cone with holes located in a circumferential direction of the head piece in an in-line order along a screw line in tiers. Diameter of holes of each next tier is larger than diameter of holes of the previous one. Between tiers there is a belt of drain holes, the diameter of which is larger than diameter of holes made in tiers. On opposite sides of the housing above and under upper edge of the head piece there arranged are two steam inlet branch pipes the cross section of which has the shape of ellipses. Perforated spiral-shaped belts of variable width are fixed spirally on the head piece perpendicular to its outer and inner surfaces. A free edge of the external belt touches the inner side of the housing; a free edge of the internal belt forms cylindrical space inside the head piece.

EFFECT: invention provides effective condensation and can be used for condensation of non-cleaned water vapour and vapours of other liquids.

2 cl, 3 dwg, 2 tbl

Description

The invention relates to designs of mixing heat exchangers for conducting heat and mass transfer processes of a steam (gas) -liquid system. The device can be used both as a condenser for contact condensation of a mixture of vapors (including contaminated and inhomogeneous) with a similar medium in a liquefied state, and as a boiler in various industries, for example, in the power industry, chemical, petrochemical, etc.

Known contact capacitor with the rotation of steam and cooling water (patent JP 3163326, F28B 3/08, 2001). The condenser contains a cylindrical body, a cover, a cone-shaped bottom with a fitting for condensate drainage, a steam supply fitting, consisting of a pipe with built-in nozzles or with vanes that facilitate twisting of the steam stream. The cover has tangentially twisting coolant inlets with integrated diffusers.

The disadvantages of the known invention are the low efficiency of the apparatus due to the loss of the twisting effect after the start of the condensation process and the limited use of the apparatus - only for condensation of pure water vapor.

A mass transfer contact device is known in which due to the presence of internal contact plates a swirling swirling flow of contacted media is formed (RU patent No. 2271848, B01D 3/24, B01D 3/30, 2006). The device comprises a housing, an inclined plate with a device for draining liquid from the upper plate to the lower one, the inclined plate consisting of several parallel layers with perforations placed on the support ring at a predetermined distance between them, while the angle between the horizontal plane of the support ring and the outer side of the outer the plate layer is taken in the range from 90 to 160 °, and the liquid, draining from the upper plate to the lower one, enters the layer of the plate that first contacts the steam or gas stream ohm

However, the effectiveness of the known device cannot exceed 90%.

The closest technical solution, selected as a prototype, is a vortex-type contact apparatus (Moskalev L.N., Ponikarov S.I., Ponikarov I.I. “Description of the experimental setup for conducting studies of the condensation process in a contact vortex apparatus” / Bulletin of Kazan University of Technology, T. 14. No. 14; Moscow-based image, and science of Russia, Kazan. National Research Technological University. Kazan: KNITU, 2011. - 318 s). The apparatus contains a cylindrical body, a cover with a spraying centrifugal nozzle, a bottom with a nozzle for condensate drainage, a regular perforated nozzle coaxially installed inside the body, which is a hollow truncated cone with holes arranged in a checkerboard pattern with four tiers, the diameter of the holes of the first or third tiers 3 mm with an intercenter distance of 4 and 5 mm, the diameter of the holes of the fourth tier is 12 mm with intercenter distances of 14 and 18 mm, drainage belts are made between the tiers holes with a diameter of 12 mm and an intercenter distance of 14 mm, and on the opposite sides of the body above and below the upper edge of the nozzle there are two nozzles for introducing steam.

The disadvantages of the known apparatus are low efficiency, not more than 73%, due to the loss of the twisting effect after the start of the condensation process, the occurrence of the “secondary” vapor effect, the limited use of the apparatus only for condensation of pure steam.

An object of the invention is to increase the efficiency of the device, expanding the range of use of the device for various working environments and eliminating the effect of "secondary" steam.

The technical problem is solved by a vortex-type heat and mass transfer device containing a cylindrical body, a cover with a centrifugal atomizing nozzle and a nozzle for removing non-condensable gases, a bottom with a nozzle for condensate drain, a regular perforated nozzle, coaxially hollow truncated cone with holes, is coaxially mounted at least four tiers arranged around the nozzle circumference, a belt of drainage holes is made between the tiers, on opposite sides of the housing above and under the upper edge of the nozzle there are two nozzles for introducing steam, the holes of each nozzle tier are arranged in a corridor order along a helix, and the diameter of the holes of the upper tier is 2 ÷ 4 mm, the bottom is 1 (K 14 mm, the center-to-center distance is 1.1 ÷ 4 hole diameters the diameter of the holes of each subsequent tier is larger than the diameter of the holes of the previous one, and the diameter of the drainage holes is 14 ÷ 20 mm with an intercenter distance of 1.5 ÷ 3 hole diameters, on the nozzle perpendicular to its outer and inner surfaces Lena spirally perforated spiral strip of variable width so that the free edge of the outer band in contact with the inner side of the housing, the inner free edge of the tape forms a cylindrical space inside the nozzle, nozzles for the injection of steam has a cross sectional shape of ellipses, the major axes are parallel to the axis of the device.

The technical result of the invention is to increase efficiency up to 98%, the ability to use the device for various working environments, including crude steam containing non-condensable gases, eliminating the effect of "secondary" steam.

The invention consists in the following. After condensing steam and coolant are supplied to the device, a vapor-liquid mixture is formed in the nozzle volume, which is discarded to the nozzle periphery under the action of centrifugal forces, which leads to the formation of a condensate film on the nozzle surface. To break the condensate film, as well as to increase the contact area of the vapor-liquid mixture, condensate and coolant, holes are arranged on the nozzle surface in tiers. The openings of the upper tier have a diameter (2-4 mm), this is necessary in order to keep the steam on the surface of the upper part of the nozzle, where partial condensation occurs upon contact with the coolant. An increase in the diameter of the openings of the upper tier more than 4 mm can lead to the breakthrough of a large volume of steam into the lower tiers of the nozzle, which will cause the formation of condensate and the possible appearance of secondary steam.

During the rotational-translational movement of the vapor-liquid mixture and the cooling liquid to the base of the nozzle, there is a continuous decrease in the amount of steam and an increase in the amount of condensate, which must be removed in a timely manner from the working space of the nozzle. Therefore, the diameter of the holes of the subsequent tier is larger than the diameter of the holes of the previous one. There is no vapor nozzle on the lower tier and the condensate formed is completely removed. The openings of the lower tier have a diameter of 10 ÷ 44 mm. With a diameter of less than 10 mm, the condensate flow will continue to twist, which will reduce the rate of condensate removal from the device, and increasing the diameter of more than 14 mm is impractical, since it does not affect the final result.

The intercenter distance of the holes of the tiers is 1.1 ÷ 4 of the diameter of the hole. With an increase in the intercenter distance of more than 4 diameters of the holes, the condensate film will not break, which will lead to a decrease in the intensity of the process.

To expand the working range of the nozzle in terms of steam pressure and coolant flow between the tiers of the holes, drainage belt belts are made. With an increase in the pressure of the supplied steam, the condensate droplets formed during the rupture of the condensate film, if the condensate is not removed promptly, can fall into the steam stream, which will lead to the formation of secondary steam. The presence of drainage belts with holes of a larger diameter than the diameter of the holes of adjacent tiers, contributes to the rapid removal of condensate from the working space of the nozzle. As a result, the efficiency of the device increases. The diameter of the drainage holes 14 ÷ 20 mm with an intercenter distance of 1.5 ÷ 3 hole diameters are optimal and provide the most rapid removal of condensate from the working space of the nozzle.

The location of the steam nozzles ensures the twisting of the incoming steam flows, which is necessary for constant updating of the contact surface of the working fluids. It is known that the larger the twist coefficient, the higher the tangential velocity of the flow and the radius of the vortex, this helps to accelerate the process of updating the contact surface. To increase the initial coefficient of twist, the nozzles for supplying steam in the proposed device, in contrast to the prototype, are in the cross section in the form of ellipses, large axes of which are parallel to the axis of the device. To maintain the twist of the flow of the vapor-liquid mixture and condensate, the holes of each nozzle tier are made along a helical line in the corridor order, which leads to constant updating of the contact surface of the vapor-liquid mixture with the coolant.

Perforated spiral-shaped tapes are mounted on the inner and outer surfaces of the nozzle in a spiral. The presence of tapes prevents the passage of steam to the base of the device, that is, in contrast to the prototype, there will be no increase in the temperature of the condensate at the outlet of the device. The proposed device provides a decrease in the temperature of the condensate at the outlet of the device to ~ 30 ° C, while the prototype only to ~ 70 ° C.

The presence of tapes also helps to maintain the rotational-translational motion of the vapor-liquid mixture.

The holes on the tapes not only increase the contact area of the working fluids, but also, in the case of supplying crude steam, help to remove non-condensable gases from the vapor-liquid mixture and condensate. The free edge of the inner spiral tape forms the cylindrical space necessary to remove non-condensable gases. Otherwise, the accumulation of non-condensable gases in the device will lead to the formation of stagnant zones ("gas cushions"), which will reduce the intensity of heat and mass transfer and the efficiency of the device. Therefore, the inventive device can be used for condensation and / or heating of various working environments, including steam containing non-condensable gases.

As the vapor-liquid mixture moves under the action of centrifugal forces, it is discarded to the walls of the housing. To prevent the escape of steam, the removal of condensate from the contact zone, which leads to a decrease in the efficiency of the device, the free edge of the outer spiral-shaped tape is in contact with the inner surface of the housing.

The combination of the above structural solutions provide the most efficient steam condensation and obtaining supercooled condensate, which avoids the effect of "secondary steam".

The invention is illustrated by the following drawings:

figure 1 presents a General view of the device:

a) - frontal section,

b) is a horizontal section of the device in the plane "AA",

C) - section "BB pipe for supplying steam,

g) - callout perforated spiral tape; figure 2 shows a General view of the nozzle of the device:

a) - view from the left, b) - view from above;

figure 3 - diagram of the nozzle of the device:

a) - frontal section, b) - top view.

The device comprises a cylindrical body 1, inside which a regular perforated hollow cone-shaped nozzle 2 is coaxially mounted, a cover 3 with a nozzle 4 for exhausting non-condensable gases and with a coaxially fixed sawing centrifugal nozzle 5 for supplying coolant, a bottom 6 with a nozzle 7 for condensate drainage. On opposite sides of the upper part of the housing 1 above and below the upper edge of the nozzle, nozzles 8 and 9 are installed for introducing steam, and the nozzles in cross section are elliptical, the large axes of which are parallel to the axis of the device (Fig. 1c). Around the circumference of the nozzle are located in the corridor order along the helix of the hole 10 tiers 11 (figa, 3A). When passing from the upper tier to the lower tier, the diameter of the holes and the center distance increase. Between the tiers, drainage belts 12 are made with the diameter of the holes, which are larger than the diameter of the holes of the tiers (Figs. 2a, 3a). On the nozzle perpendicular to its outer and inner surfaces, the outer 13 (FIG. 2) and inner 14 (FIG. 3) perforated spiral-shaped tapes of variable width are fixed in a spiral (FIG. 1 g). The free edge of the outer tape 14 is in contact with the inner side of the housing 1, and the free edge of the inner tape 13 forms a cylindrical space 15 inside the nozzle.

The heat-mass transfer device of the vortex type operates as follows. Steam with a temperature of 120 ÷ 150 ° C under pressure is fed into the housing 1 through two nozzles 8 and 9. Through a centrifugal nozzle 5 serves coolant with a temperature of 21 ÷ 23 ° C. With direct contact of steam and liquid, partial condensation of the vapor occurs, which leads to the formation of a vapor-liquid mixture. The vapor-liquid mixture progressively with small rotation moves to the upper tier of the regular nozzle 2. The steam supplied through the pipe 9 gives additional acceleration to the vortex of the vapor-liquid mixture. In the volume of the nozzle, condensation of the vapor-liquid mixture continues, the condensate formed is discarded to the periphery of the nozzle, which leads to the formation of a condensate film. The condensate film is torn, the resulting droplets flow down to the base of the nozzle and the condensate is removed through the nozzle 7. In the case of supplying steam containing non-condensable gases, these gases are removed from the device through the nozzle 4.

Comparative tests of the proposed device and prototype were carried out on systems of water vapor - water, ethanol vapor - ethanol. The results are shown in tables 1 and 2.

Table 1 The results of experimental studies of the proposed device on a system of water vapor-water Operating parameters Prototype Proposed device Overpressure in the device, MPa 0.2 ÷ 0.0 0.2 ÷ 0.0 Excessive pressure at the outlet of the device, MPa 0,0 0,0 Excessive pressure of cooling water, MPa 0.24 ÷ 0.26 0.24 ÷ 0.26 Water consumption, kg / s 0.7 0.7 Inlet water temperature, ° С 120 ÷ 150 120 ÷ 150 Cooling water temperature, ° С 21 ÷ 23 21 ÷ 23 Condensate temperature at the outlet, ° С at a flow rate of cooling water, 103 kg / s: 82 70 5.3 ÷ 6.3 10.5 ÷ 12.8 76 42 72 31 16.2 ÷ 19.1 Productivity excluding coolant, 103 kg / s at a flow rate of cooling water, 103 kg / s: 5.3 ÷ 6.3 0.5 ÷ 0.7 0.6 ÷ 0.7 10.5 ÷ 12.8 0.8 ÷ 1.0 1,0 ÷ 1,2 16.2 ÷ 19.1 1.3 ÷ 1.7 1.6 ÷ 2.2

The results of experimental studies (tables 1 and 2) show that, under the same operating conditions, the proposed device provides a decrease in the condensate temperature at the outlet to ~ 30 ° C, while the prototype - to ~ 70 ° C. In this case, the coolant flow rate to achieve the same condensate temperature at the outlet of the inventive device is three times less than that of the prototype. Thus, the proposed device allows to obtain condensate that does not require additional cooling before reuse.

table 2 The results of experimental studies of the proposed device on a pair of ethanol-ethanol Operating parameters Prototype Proposed device Overpressure in the device, MPa 0.2 ÷ 0.1 0.2 ÷ 0.1 Excessive pressure at the outlet of the device, MPa 0.1 0.1 Excessive coolant pressure, MPa 0.24 ÷ 0.26 0.24 ÷ 0.26 Ethanol vapor consumption, kg / s 0.7 0.7 Ethanol vapor temperature at the inlet, ° С 105 ÷ 120 105 ÷ 120 Coolant temperature, ° С 21 ÷ 23 21 ÷ 23 Condensate temperature at the outlet, ° С at a consumption of cooling liquid, 103 kg / s:
6.7 ÷ 6.8 81 68 13.0 ÷ 13.7 74 44 20.5 ÷ 21.8 71 29th Performance excluding cooling liquids, 103 kg / s at a flow rate of a cooling liquid, 103 kg / s:
6.7 ÷ 6.8 - 0.3 ÷ 0.4 13.0 ÷ 13.7 0.6 ÷ 0.9 0.8 ÷ 0.9 20.5 ÷ 21.8 1.1 ÷ 1.3 1.6 ÷ 2.0

The data in table 2 show that the proposed device is effective for condensing not only water vapor, but also, for example, ethanol vapor. Using the prototype for similar purposes is not economically feasible, since the minimum temperature of the condensate at the outlet is ~ 70 ° C, and the boiling point of ethanol is 78 ° C. The proposed device can be used to condense vapors of low boiling liquids with a boiling point of at least 35 ° C.

Thus: thus, the proposed heat-mass transfer device of the vortex type in comparison with the prototype has the following advantages:

- efficiency - 98%,

- complete elimination of the effect of "secondary steam",

- the possibility of using for condensation of crude water vapor and vapors of other liquids.

Claims (2)

1. A vortex-type heat and mass transfer device containing a cylindrical body, a cover with a centrifugal atomizing nozzle, a bottom with a condensate drain pipe, a regular perforated nozzle coaxially mounted inside the body, consisting of a hollow truncated cone with holes located at least four around the nozzle circumference in tiers, between the tiers a belt of drainage holes is made, on the opposite sides of the body above and below the upper edge of the nozzle there are two nozzles for introducing steam, distinguishing due to the fact that there is a nozzle in the lid for the removal of non-condensable gases, the holes of each nozzle tier are arranged in a corridor order along a helical line, and the diameter of the holes of the upper tier is 2 ÷ 4 mm, the bottom is 10 ÷ 14 mm, the center distance is 1.1 ÷ 4 hole diameters, while the diameter of the holes of each subsequent tier is larger than the diameter of the holes of the previous one, and the diameter of the drainage holes is 14 ÷ 20 mm with an intercenter distance of 1.5 ÷ 3 hole diameters, on the nozzle perpendicular to its outer and inner surfaces wells fixed spiral perforated spiral strip of variable width so that the free edge of the outer band in contact with the inner body side, the free edge of the inner tape forms inside the nozzle cylinder space, nozzles for injection of steam have a cross sectional shape of ellipses, the major axes are parallel to the axis of the device. 2. The device according to claim 1, characterized in that the wall thickness of the nozzle is 0.5 ÷ 3.0 mm

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