EP0849556A2 - Condenser for binary /polynary condensation - Google Patents

Abstract

The condenser, for a binary/polynary condensation, has the coolant flowing against the direction of mixture travel in the major part of the condensation zone. The mixture and the condensation film flow in the same direction. The tubes (4), at the tube bases (5,6), are connected to a water chamber (7,8) at the entry and outlet sides.

Description

Technical field

The invention relates to a capacitor for implementation binary / polynary condensation.

Such capacitors are required for example in Power generation systems used to increase efficiency work with a circulating substance which is in the energy cycle is easily convertible, for example an ammonia / water mixture. By changing the composition of the mixture in Circulation can be compared to the classic Rankine process At the beginning of the cycle, more heat is absorbed and at its In the end less heat is given off.

Presentation of the invention

The invention has for its object a deflator Creating capacitor for binary / polynary condensation, who works with minimal exergetic losses.

The "deflegatory" refers to the condensation a steam mixture with a change in concentration of the Phases involved in the condensation process.

According to the invention, such a capacitor is distinguished through an upright arrangement of the coolant Pipes, through an at least approximately in the upper area of the coolant pipes arranged inlet port for the condensing mixture and through a below the coolant pipes arranged collecting room for the condensate to be discharged, the inlet connection and the collecting space via one connected the condenser jacket enveloping the tubes are further characterized in that the coolant predominantly Part of the condensation space in pure counterflow to the Liquid / vapor mixture is led and the mixture and the condensate film flows in direct current, which is why the pipes flow over one tube plate with one inlet side and one outlet side Water chamber are connected.

The steam side sliding achieved with such an apparatus Temperature profile is a result of segregation or separation work, which occurs due to binary / polynary condensation. At the beginning of the condensation path, a mixture condenses, which is enriched with the heavy-boiling component of the mixture, while at the end of the condensation path condensed another mixture, which with the lower-boiling Component of the mixture is enriched.

Brief description of the drawing

In the drawing is an embodiment of the invention based on one working with an ammonia / water mixture Apparatus shown schematically.

Fig. 1

einen Längsschnitt eines deflagmatorischen Kondensators;

Fig. 2

ein Diagramm Trennarbeit S als Funktion der Konzentration des Gemisches in der Kernströmung;

Fig. 3

ein Schema zur Kondensation eines gesättigten strömenden Dampfgemische mit Temperatur- und Konzentrationsverlauf;

Fig. 4

einen Ausschnitt eines Diagrammmes mit dem Temperaturverlauf entlang der Rohre;

Fig. 5

eine Anordnung der Rohrabstützung;

Fig. 6

einen Teilschnitt durch den Kondensator mit der Befestigung der Rohrabstützung;

Fig. 7

eine Variante der Rohrabstützung im Längsschnitt.

Fig. 8

eine Dampf-Zuströmvariante des Kondensators gemäss Fig. 1.

Show it:

Fig. 1

a longitudinal section of a deflagration capacitor;

Fig. 2

a diagram separation work S as a function of the concentration of the mixture in the core flow;

Fig. 3

a scheme for the condensation of a saturated flowing vapor mixture with temperature and concentration curve;

Fig. 4

a section of a diagram with the temperature curve along the tubes;

Fig. 5

an arrangement of the pipe support;

Fig. 6

a partial section through the condenser with the attachment of the pipe support;

Fig. 7

a variant of the pipe support in longitudinal section.

Fig. 8

a steam inflow variant of the condenser according to FIG. 1.

It is only essential for understanding the invention Elements shown. The flow direction of the work equipment is marked with arrows.

Way of carrying out the invention

The apparatus shown in Fig. 1 is usually different Heat and mass transfer in a not shown Column associated. So he could be the bottom part of one represent such a pillar. It exists in its outer form essentially of cylindrical parts, namely one upper inlet connection 1, a lower collecting space 2 and in between the inlet port with the collecting room connecting capacitor jacket 3. All elements are in vertical arrangement and are from the condensed Flows through the mixture from top to bottom.

In the present case, this condensable mixture consists of ammonia (NH ₃ ) and water (H ₂ O). It has an ammonia concentration of 0.6 to 0.3 parts by mass. It is fed to the inlet port 1 at a pressure of approximately 4.0 to 1.5 bar and at approximately the dew point temperature, ie close to saturation.

The actual heat exchanger consists of a bundle vertically arranged tubes 4, from the coolant, here Water that flows from bottom to top. These pipes, several thousand of which, depending on the desired performance may be present, preferably have a length of approx. 5 to 20 meters. They are over in classic construction a tube sheet 6, 5 with an inlet-side water chamber 7 and an outlet-side water chamber 8 connected. This Water chambers are one with a feed line 9 respectively Lead 10 provided. These penetrate the walls on the one hand the inlet connection 1, on the other hand the collecting room 2 and are in the cooling circuit, not shown switched.

The correct functioning of the device depends essentially that a clean counterflow between cooling water and steam mixing is realized. The transition from Inlet connection to the condensed part on the plane of the upper tube sheet 5 narrowed in a funnel shape. With this As a measure, the steam mixture is forced into the tube bundle. In addition, the steam mixture is said to be marginal largely prevented. The rejuvenation resp. the diameter the capacitor jacket is therefore dimensioned so that the annular gap 11 between the tubes of the outer bundle periphery and the capacitor jacket as tight as possible is. It should be a maximum of twice the clear width between correspond to two neighboring pipes.

The empty volume portion of the tube bundle on the steam side on the sum of all pipe sizes with regard to the trickle film [Flow rate in kg / m * sec], is such that the speed of the condensate film flowing down the pipes - which with turbulent film approx. 0.8 to 1.2 m / sec is - about the average flow velocity of the condensing steam mixture corresponds. With this The measure is the heat and heat to be described below Mass transfer between the co-flowing steam mixture and the condensate film ensured.

The transition from the condensed section to the collecting room 2 is slightly expanded in the plane of the lower tube sheet 6, so that the condensate that collects on the tube sheet runs off can. This extension can be like the top taper also be made funnel-shaped.

The circular lower tube plate 6 is in its central area penetrated by a tube 17, which in its in the part protruding into the condensation space is perforated. This tube 17 is for the removal of the non-condensable gases determined from the condensation space. For this it is through the lower water chamber 7 and the wall of the collecting room led out of the apparatus and connected with suitable suction means. The remaining condensing portion from the extracted Mixture which consists practically only of ammonia, is recovered in a downstream absorption column.

• Er muss maximale Trennarbeit leisten, weshalb eine deflagmatorische Kondensation anzuwenden ist; als zwingende Folge hiervon muss er mit kleinen Temperaturdifferenzen arbeiten.
• Der einmal gebildete Kondensatfilm soll auf seinem Weg zum Sammelgefäss integer bleiben, d.h. entlang der Kondensationsstrecke soll es zu keiner Rückvermischung (back-mixing) von Kondenssat und Dampf kommen. Am besten erreichbar ist diese Forderung duch einen Gleichsrom zwischen Kondensatfilm und Dampfmischung.
• Schliesslich soll das Kühlmittel im Gegenstrom zu Dampf und Kondensatfilm strömen.

To minimize the exergetic losses mentioned above, such a capacitor must meet the following conditions:

• He has to do maximum separation work, which is why deflagmatory condensation is to be used; as a consequence, he has to work with small temperature differences.
• The condensate film once formed should remain integral on its way to the collecting vessel, ie there should be no back-mixing of condensate and steam along the condensation path. This requirement can best be achieved by means of a direct current between the condensate film and the steam mixture.
• Finally, the coolant should flow in counterflow to steam and condensate film.

In the diagram in FIG. 2, the separation work is a function of Concentration shown at different temperature differences. It is understood that in this context Notification of exact numerical values has to be dispensed with, because they depend on too many parameters. For the Understanding of the invention are the following qualitative Statements sufficient.

On the abscissa is the concentration Y of a gaseous, condensable mixture applied. On the ordinate is the separation work or segregation S specified. The 4 curves stand for 4 different driving potentials heat and mass transfer, i.e. the temperature differences between mixture and coolant. The 4th Temperature differences 30, 20, 10 and 5 Kelvin.

The general course of the curve shows that the cutting work on the largest is the low-boiling at low mass fractions Liquid in the mixture to be condensed.

The diagram also teaches that to achieve one possible large separation work, the smallest possible temperature difference between mixture and coolant.

Finally, it can be seen that there is a very large temperature difference leads to practically no separation work. In this In this case, a so-called total condensation takes place, i.e. that Mixture condenses practically as a pure substance on one Isotherm.

The invention aims to avoid the latter. The goal is one non-isothermal condensation of the mixture with a corresponding Reduction of essential exergy losses.

According to the above, there must then be a maximum Good condensation. Accordingly, this becomes a very low driving force Temperature difference of 5 Kelvin, for example, which of course leads to very large exchange areas leads.

The operation of the invention is described below with reference to Fig. 3 explains which schematically the condensation of a shows saturated flowing steam mixture. At 21 she is outer tube wall one of the coolant from bottom to top flowed through pipe. This tube wall forms one vertical cold surface whose temperature is below the dew point temperature - compared to that in the concentration in The core of the flow - lies. It gets from top to bottom flowing saturated vapor mixture with the cold surface in Touch, a condensate forms, which is a film 22 flows down the surface. In contrast to the condensation pure substances call the phase balance and kinetics Formation of a vapor-side mass transfer boundary layer and thus a temperature drop at the phase boundary between Film and steam. The result arises in this Area an enrichment in the low-boiling component of the mixture. The concentration is in this area higher than in the core flow.

These facts are shown in the figure. Y _G denotes the concentration of the lower-boiling component of the mixture, which is constant in the core flow, which is distinguished by its horizontal course. At the phase boundary between film and vapor, on the other hand, the concentration rises to point A. In the condensate film, however, the concentration drops from point B at the phase boundary to the pipe wall. Points A and B are in the so-called phase equilibrium, and the associated temperatures can then be determined from an enthalpy diagram. The temperature curve is designated T in the diagram, T _{K representing} the temperature in the core flow it and T _{W representing} the temperature of the condensate film on the tube wall.

It is understood that this consideration is only local to the the respective concentration applies. With increasing condensation, in which first the heavy-boiling component condenses, the concentration changes continuously of the mixture in the core flow. The considerations above are therefore to be carried out continuously to achieve the final To determine the course of condensation.

Fig. 4 shows schematically the course M of this non-isothermal deflagmatory condensation of a mixture in one Diagram "temperature along z" [T, z], where z is the height of the vertical coke deposition room. W denotes the Temperature curve of the coolant. With R is the isothermal Course of a total condensation called. ΔT represents the achievable profit, which in the present case is a Ammonia / water mixture several Kelvin, e.g. 5-8K can.

After all, it can be seen that despite the need for large Exchange areas of constructive effort in the present Invention is much less compared to conventional Methods in which a comparable, but in in any case worse result can only be achieved by that multi-pressure condensers are used in the Rankine process reach. Multi-pressure capacitors can make this profit realize only gradually, as shown in Fig. 4 by the Course N is shown, in contrast to the invention sliding condensation M, which has a constant course.

Also decisive for the proper functioning of the Capacitor is the requirement that disturbances in the flow can be largely prevented in the condensation chamber. Such disturbances could lead to undesired mixing of the condensate film and the vapor phase cause what is negative affects deflegmatory condensation. Instead of The support plates that have been customary in capacitors so far are therefore provided the tubes by horizontally extending bands 12, 13 to support. These bands are mutually in one or several levels arranged along the length of the pipe.

Such a pipe support is sketched in FIG. 5. At the chosen pipe arrangement is a so-called Triangular arrangement that is known to be the The largest possible number of pipes can be accommodated. A first layer of bands 12 is crosswise from a second arranged position of bands 13 underlaid. With the narrow sides of their tapes form only an insignificant one Blocking of the cross-section flowed through.

In Fig. 6, the leadership respectively. Attachment of such tapes on Capacitor jacket 3 shown. In the simplest case, they are Tapes can be moved in a heat-circulating manner around the jacket Leadership 14 a. The ring-shaped guide can turn on attached several locations of the circumference of the jacket in supports 15 be.

A variant of the pipe support is shown in Fig. 7. Toothed belts 16 are used here. Two each Layers can be nested into one another via the toothing and result in a stiff grid through which the pipes 4 can be easily inserted during assembly then with the tube sheets 5 and 6 positive and / or non-positive to be connected.

In order to avoid harmful pipe vibrations, such Pipe supports depending on the pipe diameter and wall thickness in Distance from 1 to 1.2 m above the longitudinal extent of the condensation space appropriate.

Finally, in Fig. 8 is a steam inflow variant for Condensation room shown. Functionally identical elements are included the same reference numerals as in Fig. 1. In this Execution is the usually circular upper tube plate 5 expanded in diameter. On its outer periphery and on the outer wall of the capacitor jacket 3 a circumferential annular chamber 18 is welded on. This is in Example provided with two lateral steam supply lines 19. Via suitable openings 20 in the capacitor jacket 3, the are evenly distributed over its circumference Radially vapor into the tube bundle. Although with this Solution the top part of the tubing not in counterflow pressurized, but this affects the type of steam introduction the way it works. Because the steam becomes immediate redirected to the vertical and in this area no pronounced capacitor film has formed yet. With This solution can reduce the overall length due to the large needed exchange areas already very "long" apparatus be reduced somewhat.

Reference list

1

Inlet connector

2nd

Gathering room

3rd

Capacitor jacket

4th

pipe

5

upper tube sheet

6

lower tube sheet

7

inlet-side water chamber

8th

outlet-side water chamber

9

Cooling water supply

10th

Cooling water discharge

11

Annular gap between 4 and 3

12th

Support bands

13

Support bands

14

Bands guide

15

Support from 12.13 to 3

16

toothed bands

17th

Pipe for the extraction of the inert gases

18th

Ring chamber

19th

Steam supply

20th

Steam inlet opening

21

Pipe wall

22

Condensate film

Claims (7)

Condenser for the binary / polynary condensation of a steam mixture, characterized by an upright arrangement of the pipes (4) through which the coolant flows, by an inlet connection (1) for the mixture to be condensed, which is arranged at least approximately in the upper region of the coolant pipes, and by one below the coolant pipes ( 4) arranged collecting space (2) for the condensate to be discharged, the inlet connection (1) and the collecting space (2) being connected to one another via a condenser jacket (3) enveloping the pipes (4)
further characterized in that the coolant is conducted in a pure countercurrent to the mixture in the major part of the condensation space and the mixture and the condensate film flow in cocurrent, for which purpose the tubes (4) each have a tube plate (5, 6) with an inlet side and an outlet side Water chamber (7, 8) are connected. Capacitor according to claim 1, characterized in that the empty volume portion of the tube bundle in relation to the Sum of all pipe circumferences is such that the speed of the condensate film flowing down the pipes (4) (22) about the average velocity of the condensed Vapor mixture corresponds. Capacitor according to claim 1, characterized in that the pipes (4) in the condensation chamber in at least one Level by horizontally arranged belts (13, 14, 16) are supported, which in the condenser jacket enveloping the pipes (3) are stored. Capacitor according to claim 1, characterized in that the lower tube sheet (6) of at least one tube (17) is permeated, which in its in the condensation space protruding part is perforated and which through the lower water chamber (7) is led out of the apparatus for Discharge of the non-condensable gases from the condensation room. Capacitor according to claim 1, characterized in that the transition from the inlet connection (1) to the pipe Condensation part is narrowed in a funnel shape. Capacitor according to claim 1, characterized in that the inlet port (1) for the mixture to be condensed an annular chamber (18) with at least one steam feed line (19) has, via which annular chamber the mixture through steam inlet openings (20) in the condenser jacket (3) in the condensation space flows in. Capacitor according to claim 1, characterized in Transition from the condensed section to the collecting room () is expanded in a funnel shape.

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