UA44364C2 - DEVICE FOR HEAT, MASS EXCHANGE AND REACTION PROCESSES - Google Patents

Abstract

The invention relates to apparatuses for conducting heat, mass exchange and reaction processes in a gas (steam) – liquid system. It may be used in the chemical, petrochemical and related industries. For the purpose of intensification of the processes of heat and mass exchange and utilization of heat of the waste steam of low temperature potential withdrawn from steam turbines or heat power stations a tubular vertical heat exchanger of the apparatus is made as heating tubes in the middle of which a multistage film-forming nozzle is located concentrically. It consists of central tubes of smaller diameter with openings located with spacing between the rows. Step-like in inner diameter hubs are fixed above the openings. At the upper part the central tubes are provided with supporting centering hubs, at the lower part – with centering fins. Vertical slots are made in the upper part of the heating tubes.

Description

The invention relates to devices for carrying out heat, mass transfer and reaction processes in the gas (vapor) - liquid system, when carrying out liquid-phase exothermic and endothermic reactions, in particular for distillation, and can be used in chemical, petrochemical and related industries.

The method of carrying out heat, mass exchange and reaction processes and the tubular film apparatus for its implementation are known.

The method consists in supplying the initial solution in the form of a thin film on the outer surface of the contact tubes of the heat exchanger, introducing heating steam into the inner cavity of the contact tubes and maintaining a vacuum of a certain magnitude in the apparatus, in the contact zone of the initial solution with the contact tubes. The apparatus contains a vertical tubular heat exchanger with tube boards for attaching contact tubes, collectors of solution, distillate and condensate, nozzles, respectively, input and output of the heating agent, input of the initial solution and distillate, input of heating steam, output of condensate and vacuum connection.

IP A.s. USSR M 1703160, MKV B 01 O 1/06, 1/22, pub. 07.01.92 BV M 11. The method is carried out with the help of the apparatus as follows: a heat agent is introduced from the bottom up into the inter-tube space of the heat exchanger, heating steam is fed from the top down through the nozzle into the tube space, and the initial solution in the form of a thin film from top to bottom flows onto the outer surface of the contact tubes through a special film former. In the apparatus, in the tube space, between the main and contact tubes, a vacuum of a certain value is maintained, during which intensive evaporation of the solution from the surface of the contact tubes occurs. The formed vapors condense on the inner surface of the heat exchange tubes and in the form of distillate flow into the lower part of the device and are removed through the outlet pipe. The evaporated solution flows down the outer surface of the contact tubes, collects in the collector and is also discharged from the device through the outlet pipe. The disadvantages of the method and apparatus are a low coefficient of effectiveness due to the sensitivity of the contact tubes to their deviation from the vertical position, that is, the separation of the film of the solution from the surface of the contact tubes, as well as a decrease in the quality of the distillate as a result of individual splashes of the solution from the surface of the contact tubes during the boiling-evaporation process.

The closest in terms of technical essence and the effect achieved is the method of conducting heat, mass transfer and reaction processes, which consists in the interaction of the flows of the heating agent and the solution, which is supplied from top to bottom in the form of a film and a film-tube apparatus, which contains a vertical tubular heat exchanger with film-forming nozzle, vapor-liquid phase separator, circulation water collector, secondary steam collector, circulation pump, connecting pipelines and process nozzles. Moreover, the evaporated solution is fed into the film-forming nozzle under excessive pressure.

The output liquid is forcibly fed to the film-forming nozzle, where it is formed and further flows down the inner surface of the hollow tubes of the film-former and the vertical tubes of the heat exchanger in the form of a uniform film. The vapors formed during the evaporation of the liquid enter the separator and are discharged through the steam nozzle. (2. AS USSR M 1621994, MKV B 01 D 1/22, BV M Z 1987)

The disadvantages of the method and the film-tubular apparatus are limited productivity due to an increase in the resistance of the vapor-liquid phase to the separator in the area of the film-forming nozzle in one direction - from the bottom up and, as a result, an increase in heat energy costs. In the process of work, the possibility of detachment of the film from the inner surface of the pipes is not excluded.

The invention is based on the task of improving the device for carrying out heat, mass transfer and reaction processes by creating a vacuum of a certain size in the inter-tube and tube space of the heat exchanger, which ensures intensive evaporation of the liquid from the inner surface of the heat exchange tubes, regardless of their length and even with some deviation of the heat exchange tubes pipes from a vertical position, directing the formed vapor-liquid mixture to the vacuum sources from both ends of the heat exchange elements, which increases the contact time of the film creeping from top to bottom with the heating surface of the tubes, intensifies the process of heat and mass exchange, and increases the efficiency of the device as a whole.

The task is achieved by the fact that in the device for carrying out heat, mass exchange and reaction processes, the interaction of the heating agent and the liquid supplied from top to bottom is carried out both under excessive pressure and under vacuum, the resulting gas-liquid mixture is taken in two directions and separately fed into the separator, as a heating agent the heat of low-potential spent steam after steam turbines of large-scale units for the production of ammonia, methanol or thermal power plants is used, the device contains a collector of circulating outlet water connected in series along the line of the steam-gas mixture, a tubular vertical heat exchanger, a vapor-liquid phase separator , collector of secondary (juice) steam, circulation pump, connecting pipelines and process nozzles for supplying the initial circulation liquid, heating agent, creating a vacuum, for the removal of inert gases, concentrated solution and condensate, output of secondary (juice) steam, according to the proposed const ruction, the tubular vertical heat exchanger is made in the form of heating pipes, inside which a multi-cascade film-forming nozzle is concentrically located, which is a central tube of a smaller diameter with holes that are located in a step and between rows, bushings are fixed above the holes, stepped on the inner diameter, installed with a gap c between the inner surface of the heating tube and the outer surface of the bushing and with a gap sg between the inner surface of the bushing and the outer surface of the central tube, in the upper part of the central tubes are supplied with support-centering bushings, and in the lower part - centering ribs, vertical slits are made in the upper part of the heating tubes , in the upper part of the heat exchanger and the lower one, between the heat exchanger and the collector of the circulating output liquid, the upper and lower separation chambers are located, respectively, connected to the separator, which is located above the heat exchanger, between the upper separation chamber 1 secondary (juice) steam collector and has a tan genial input from both separation chambers.

The use of the heat of low-potential waste steam when creating a sufficient difference in vacuum, in the pipe space deeper than in the inter-pipe space, allows for intensive evaporation of the liquid from the inner surface of the heat exchange pipes and makes it possible to significantly increase the efficiency of the device, to utilize the heat after the steam turbines of the production of large-capacity units ammonia, methanol or thermal power plants, which makes the process economical, reduces energy costs per unit of production.

The presence of a multi-cascade film-forming nozzle, which is central tubes of a smaller diameter, installed concentrically with a gap si, sufficient for the installation of film-formers, made in the form of bushings stepped on the inner diameter, fixed with a step Пп on the central tubes above the holes in them and with a gap c - 1 - 1.5 mm between the outer surface of the bushings and the inner surface of the heat exchange tubes and with a gap o sufficient for the passage of steam into the central tubes through the holes in them, makes it possible not only to form a liquid film, but also immediately, starting from the end of the tubular heat exchange element, evenly distribute it over the entire surface of the heat exchange, which improves the efficiency of heat and mass exchange, increases the productivity of the device in terms of evaporated moisture and improves the quality of the finished product.

The placement of the multi-stage film-forming nozzle in the falling film evaporator makes it insensitive to the presence of deviation of the heating tubes from the vertical position.

The installation of preliminary separation chambers above the heat exchanger and below, between the heat exchanger and the collector of the circulating liquid, allows the secondary (juice) steam to be taken from the central tubes in two directions, which ensures preliminary rough separation of the secondary steam from splashes and significantly (by a factor of 2) reducing the movement resistance steam in these tubes and, as a result, increase the productivity of the installation as a whole.

The presence of the collector of the circulating liquid and its placement at the bottom of the device in combination with the pump allows creating the maximum load regardless of the temperature of the incoming feed liquid.

The essence of the invention is explained by the drawings, where: in fig. 1 - a device for implementing a method of carrying out heat, mass exchange and reaction processes is presented, in fig. 2 - vertical section A-A of the device in fig. 1, in fig. C - node 1 on the tubes in fig. 2.

The device for carrying out heat, mass exchange and reaction processes contains collector 1 of circulating source vaporized liquid, vertical tubular heat exchanger 2, horizontal centrifugal separator From the vapor-liquid phase, collector 4 of secondary (juice) steam, circulation pump 5, connecting pipelines 6, 7, 8, 9, 10, 11, technological nozzles for the supply of evaporating liquid: circulation - 12, fresh outlet - 13, heating steam 16, a preliminary separation chamber 17 is installed in the upper part of the heat exchanger 2, and in the lower one, between the heat exchanger 2 and the collector 1, on the outside of the shell of the collector, the second preliminary separation chamber 18, which communicates with the inner space of the collector 1 through holes 19, the chamber 18 is provided with a hatch 20. The collector 1 is supplied with a level gauge 21. A shut-off valve is installed on the connecting pipeline 6 between the collector 1 and the circulation pump 5 22.

A shut-off valve 23 and a pipeline 24 with a control valve 25 for the output of a concentrated solution are installed on the connecting pipeline 7. The vertical tubular heat exchanger 2 with a sliding film from top to bottom contains heating tubes 26, inside which a multi-cascade film-forming nozzle is concentrically mounted, which contains tubes 27 of a smaller diameter with holes 28 and a step of 300-600 mm between rows in height, on which bushings 29 are fixed above the rows of holes, stepped in the inner diameter and installed with a gap (c - 1 - 1.5 mm between the inner surface of the tube 26 and the outer surface of the sleeve 29 and with a gap sg between the inner surface of the sleeve 29 and the outer surface of the tube 27, sufficient for the free passage of the secondary steam, and between the tubes 27 and the tubes 26 there must be a gap si sufficient to place the stepped bushing 29. The tubes 27, in the upper part, are provided with supporting and denting bushings 30 and in the lower part with centering ribs 31, and the heating tubes 26 in the upper part are vertical slits 32 for the passage of evaporating liquid into the upper and lower separation chambers 17, 18 the diameter of the pipelines 8, 9 are connected to the separator 3, and the entrance to the separator is made tangentially, in the lower part, the separator is connected to the collector 1 with the help of drainage pipelines 11 for removing splashes from the separator, which are carried with the secondary steam and connected to collecting manifold 4 of secondary steam through connecting pipelines 10. Steam selection takes place along the axis of the separator 3. Separator C is installed on the service platform 33, which rests on the previous separation chamber 17.

The method of carrying out heat, mass exchange and reaction processes using the device is carried out as follows:

First, before filling the circulation collector 1 with the initial solution that evaporates, for example, water, a heating agent (steam) is supplied through the nozzle 14 into the pipe space of the vertical tubular heat exchanger 2 and is turned on (when using the heat of low-potential spent steam after steam turbines of various purposes a system of staged separate vacuuming through the nozzle 15 on the heating steam and through the collecting collector 4 deeper on the secondary (juice) steam, then the circulation pump 5 is activated, which supplies the solution (for example, water), which evaporates, through the slits 32 inside the tubes 26 and when the temperature of the circulating solution (water) is below the boiling temperature under the specified conditions under vacuum by 5 - 1090, the process of intensive vaporization (evaporation) of the circulating liquid begins on the inner surface of the heating tubes 26, from where the secondary (juice) steam enters the tubes through the holes 28 27 and further moves in two directions hgo ru and down through the separation chambers 17 and 18 through the pipelines 8 and 9 into the centrifugal separator 3, is separated from the splashes and through the pipelines 10 enters the collective collector 4 and further to condensation or for other purposes. At the same time, when the set temperature of the circulating solution (water) is reached, the control valve 25 is activated to remove the concentrated solution from the system, maintaining the level in the reservoir 1. Through the fitting 13, fresh solution (water) that evaporates is fed.

Thus, the proposed method of carrying out heat, mass transfer and reaction processes and the device for its implementation make it possible to utilize the heat of the spent steam of low temperature potential after steam turbines for the production of large-capacity aggregates of ammonia, methanol or thermal power plants, to reduce energy costs per unit of production, to intensify the process of heat and mass exchange, to significantly (by 2 times) reduce the resistance of steam movement in the tubular elements of the heat exchanger and, as a result, to increase the productivity of the installation as a whole.

and. station

Fa Te nya - their sg 7

EE INN

IN and nin 1 E-A-CHI | U.S

With o h

AND

Fig. 1

A- A.

OZ

TE Ya. 3 8 U ha She 30 o v; punk guilty utensils sisann

RE: ra: "Di shZ-A- (| still in-2- Dn pon sha sas 25 | | KAF i r; and et na kaya shk 'v m-- 71 Bach

TINY YAH KOMI LYSH MA ZH ;

Fe vybsetshchy shk M

Fig. 2

29. I | | and ЮА У ради. I and | g dyan, I she; and | SHE

CJSC NO

"NO 1

More Y (more I

M More

Y, | Z y I Я " 88 I Mass I ote DEN tu NO Me MOVNI

SHA DK NIK

VO KO MO KI

ZV N A YN Y VN

26 | | | in the

Me: and | AND

Well, in the DIT - machine and

YAG-e-1-1-e-d; nn in

IN. TV VK Ku -I-- 0 Mu CI! i t a z a BI i o I i ryn KY: pi THEYAKI CHA

Fig. WITH

Claims (3)

1. A device for carrying out heat, mass exchange and reaction processes, which contains a collector of circulating source liquid, a tubular vertical heat exchanger, a vapor-liquid phase separator, a collector of secondary (juice) steam, a circulation pump connected in series along the line of the vapor-gas mixture, with connecting pipelines and process nozzles for the supply of the initial circulating fluid, the heating agent, the creation of a vacuum, for the removal of inert gases, concentrated solution and condensate, the output of secondary (juice) steam, which is distinguished by the fact that the tubular vertical heat exchanger is made in the form of heating pipes, inside of which a multi-cascade film-forming nozzle is located concentrically, which is a central tube of a smaller diameter with holes that are located in a step and between rows, bushings are fixed above the holes, stepped in the inner diameter, installed with a gap b between the inner surface of the heating tube and the outer surface of the bushing and with a gap 02 between the inner surface of the sleeve and the outer surface of the central tube, the upper part of the central tube is equipped with support-centering sleeves, and the lower one with centering ribs, vertical slits are made in the upper part of the heating tubes. 2. The device according to claim 1, which is characterized by the fact that in the upper part of the heat exchanger and the lower, between the heat exchanger and the collector of the circulating output liquid, the upper and lower separation chambers connected to the separator are located, respectively. 3. The device according to claim 1 or 2, which differs in that the separator is located above the heat exchanger, between the upper separation chamber and the secondary (juice) steam collector and has a tangential inlet from both separation chambers.