DE3929519A1 - Centrifugal condenser for single or multiple media - with vapour pumped to and from external exchanger to use heat - Google Patents

Abstract

Rotor wheel of a centrifugal condenser, driven by an electric motor with parallel peripheral ribs, projects above the surface of a bath of cooling liq., esp. oil, which collects waste heat from the motor and frictional heat from an external fan cooler. An insulating casing separates this bath from an outer annular bath of second cooling liq., esp. water, in the base of an evapn. chamber spanned near its heat by a porous evapn. ring, with a gap between the casing and the ring for return of centrifuged molecules to the second liq.. Evapd. water is fed to an external heat exchanger to provide useful heat, with used vapour returned for condensn. Separate pumps maintain circulation of liq. and vapour. USE - For gas liquifaction, or as combined compressor/condensor in refrigeration or heat-pump circuits.

Description

General

The centrifugal condenser as a single or multi-component system, is general for the suction and liquefaction of Steaming / gases, especially in the low pressure range suitable with a large specific steam volume.

It applies

• - As an aggregate for the liquefaction of technical gases
• - as a combined compressor / condenser in compresses ion cooling circuits. (For the substitution of fluorine-chlorine Hydrocarbons can e.g. B. water or others environmentally friendly refrigerants with large spec. volume be used.)
• - analogously as a combined compressor / condenser Heat pump cycles
• - as an evacuation device (vacuum pump)
• - As an extraction device for gases

Basics

As is well known, the forces between molecules in the liquid Physical state depending on the distance more attractive or less bumping nature. In the liquid state it is Movement of the molecules so large that molecules from the An pulling range of an adjacent molecule into one others can switch over.

With evaporation, the movement of the molecules is so strong the kinetic energy of the corresponding molecules so ge grow that they have the attraction of their neighbors beard molecules overcome and the fluid association being able to leave.

One acts on molecules on the surface of the liquid one-sided resul directed into the interior of the liquid driving force. You own a higher proportion of pots tial energy as molecules inside the liquid. As is well known, this results in the surface tension a liquid.

In an isolated system (container) a substance should now 1 (e.g. water), partly in liquid, partly in steam shaped physical state (wet steam). At the same time Statistically speaking, the weight condition is moving, despite the untidiness movement of the steam molecules onto each surface unit of the they enclose a certain equal number of walls  Steam molecules and exert a corresponding impulse. So far they will meet them on the wall surfaces, similarly like perfectly elastic balls. As far as it goes the liquid-covered bottom area of the container the situation is more complicated.

The collision with the existing liquid Molecules causes that in most cases relevant gas molecule from which it is impacted giving liquid molecules is captured and instead, another existing liquid mole cool away from his neighbors' area of attraction can and the role of the captured gas molecule takes over, d. H. leaves the fluid dressing.

In the equilibrium state between wet steam and Liquid is the number of impinging gases molecules on the liquid surface equal to that molecules emerging from the liquid surface in the gas room.

Would the existing liquid volume from one rotating liquid ring exist, the Liquid molecules under a centrifugal force are thrown, the simplified representation applies here Mechanism of the impinging or exiting steam mo no longer read on / off a liquid surface. Impinging steam molecules that come from inside the Liquid ring are detected and absorbed, experience an acceleration on the circular existing speed of the surrounding Liquid molecules and are then subject to if the appropriate centrifugal force. The on Place these gas molecules normally as Liquid molecules that become gas molecules become due to the centrifugal force at the outlet from the Liquid dressing additionally hindered.

The kinetic energy of the captured gas molecules as well as those related to acceleration the same on the peripheral speed of the liquid kinetic energy associated with the ring, furthermore due to the resulting liquid friction, cause an increase in internal energy of the liquid ring. It turns out depending on the circulation speed and geometry of the liquid ring another state of equilibrium.

Now this isolated system described here expanded in that the rotating liquid outside cylinder continuously cooled and at the same time a liquid reservoir elsewhere there is a continuous re-evaporation  enables, result in equilibrium and Persistent state of this then no longer completed Systems two liquids with different internal energy, also wet vapor that of the liquid with lower energy status.

There is a constant flow of material from the liquid with low inner energy through the path of Evaporation to the liquid with higher energy, d. H. to the rotating liquid ring.

The work required for this is through acceleration the one captured by the rotating liquid ring and absorbed gas molecules onto the circular one Speed of the rotating liquid ring provided, this must therefore have a motor drive constantly kept at its rotational speed will.

Depending on the gas to be liquefied, the required centrifu galkraft and thus the rotational speed and speed can become very large, it is possible to get the liquid ring in two different substances with different specifi divide weight and different thermo to develop dynamic properties.

In this case, an outer ring from the material 1 to be liquefied, an inner ring from another, specifically lighter and not at the temperatures that occur and pressure evaporating liquid (substance 2) exist. Then hit the liquid surface of the substance 2 found gas molecules of substance 1 are also absorbed, accelerated to circumferential speed and increased walking due to the additional centrifugal force acting on them and due to the higher specific weight in radial Direction to the outer liquid ring (fabric 1).

As a result of the pressure of the inner liquid ring (substance 2) already acting on the outer liquid ring (substance 1) and the centrifugal force also acting, there is liquefaction pressure here, i.e. the penetrating molecules of substance 1 liquefy here at a higher temperature level and thereby increase the inner energy of the outer one Liquid ring (fabric 1). This increase in energy is then dissipated to the cooling medium via the outer jacket of the impeller 1 .

In this process, the outer liquid ring (Substance 1) normally released, released steam molecules not only by their own centrifugal force, but also additionally by the pressure of the inner liquid ring (fabric 2) with special needs. Molecules that still find their way through the inner Step on liquid ring (substance 2) towards gas space, who which is additionally hampered by the existing fluid friction and are still subject to the corresponding during this period Centrifugal force.  

Summarized:

The penetration and absorption of vapor / gas molecules of the Substance 1 is made by arranging an additional inner Liquid ring (fabric 2) supports the escape additionally difficult. As a result, compared to one with only one substance operated system the necessary scope speed or engine speed significantly lower will.

The so-called centrifugal works according to this principle capacitor. It practically includes the classic ones Elements of the compressor and condenser in one Aggregate.

Device construction and functional description

For further understanding, the mode of operation of the Centrifugal condenser as a single or multi-component system are explained in the following circuit diagram.

According to Figures 1 and 2, the centrifugal capacitor consists of an impeller ( 1 ) with an electric drive motor ( 2 ) which is supplied with electrical energy via a frequency converter ( 3 ). To accommodate the or the liquid ring (s), the impeller has a corresponding recess ( 4 ) which is formed with ribs in order to enable a frictional connection between the impeller and the liquid. Most of the impeller and the drive motor are in a cooling medium (substance 3), for. B. oil bath, which dissipates the heat loss from the drive motor and from the liquid friction, furthermore the condensation heat of the vapor molecules absorbed by the rotating liquid ring to the external cooler ( 5 ). For this purpose, the cooling medium is circulated accordingly via a pump ( 6 ). The external cooler ( 5 ) can be cooled with air or water, with gas or with another liquid.

The impeller with the drive motor and the surrounding cooling jacket is surrounded in a ring by an insulated wall ( 16 ) from the evaporation chamber ( 7 ). About a spray device ( 8 ) is heated in the useful heat exchanger ( 9 ) substance 1, z. B. water, ver sprayed or distributed to let it collect again in the lower area. The evaporation process cools substance 1 (for example water) and can be returned to the useful heat exchanger ( 9 ) via the pump ( 10 ). In order to avoid droplet formation in the suction area of the impeller, the evaporation chamber has an annular demistor package as a drop cutter ( 11 ).

The impeller has to drain the excess condensate (substance 1) corresponding holes which are structurally arranged obliquely inwards to ensure a constant liquid supply in the area of the (s) provided liquid rings (s) in the impeller, and / or a throttle point (not drawn). The resulting condensate then flows through these holes through a further horizontally arranged hole or into the annular free space and is returned to the concentrically arranged return duct ( 13 ) in the direction of the evaporator chamber ( 7 ) by centrifugal action.

Any liquid parts of substance 2 that are carried along (in particular during the start-up phase) can be discharged as a mixture of substances 1 and 2 via a special sniffing device (similar to flooded evaporators for oil return) and via the separator ( 18 ), additional auxiliary pump ( 19 ) and one Solenoid valve ( 17 ) are fed back to the impeller.

In practical operation, the system now works as follows:

First the entire system must be evacuated, then the inner jacket space ( 12 ) and the external cooler ( 5 ) are filled, as well as the corresponding piping system with cooling medium substance 3 (e.g. oil), furthermore the evaporation space ( 7 ), useful heat exchanger ( 9 ) and corresponding piping system to substance 1 (e.g. water). In addition, substance 2 must be added, the latter usually remains at a standstill in the bottom area of the impeller.

The drive motor ( 2 ) of the now operational system is started via the frequency converter ( 3 ) and brought to the required nominal speed. At the same time, the existing pumps ( 6 and 10 ) are started and the annular space ( 4 ) of the liquid ring is filled with substance 1 (e.g. water) via a bypass line, which is opened for a limited time via a solenoid valve ( 15 ). The excess part immediately flows through the holes and goes straight back into the evaporation chamber.

As described at the beginning, there is a constant evaporation in the evaporation chamber ( 7 ) as a result of the supply of heat to the useful heat exchanger. The resulting steam passes through the impeller to the liquid ring (s), is largely absorbed there, liquefied and relaxed on the way via the drain holes and throttle point to the return duct ( 13 ) back into the evaporation chamber ( 7 ).

Partial evaporation occurs due to the expansion process the condensate, similar to an expansion valve a refrigeration cycle, which cools the condensate to the temperature level of the evaporation space and decreases the internal energy of the evaporating substance 1 (e.g. water) at.  

The resulting heat of loss and condensation is given off in cooling medium via the external cooler ( 5 ) to air or water, gas or other liquid.

Vapor molecules substance 1 (e.g. water) that collect in the upper area of the inner jacket space ( 12 ) have a corresponding overheating, which corresponds to the temperature of the inner jacket space.

The inflow of the steam molecules to the inner ring surface of the rotating liquid ring is comparable to the inflow of steam molecules in a jet apparatus. Due to the relatively high speed of the steam molecules when water vapor is slightly overheated in the range of + 4 ° C, the average speed is over 600 m / s, the existing intake cross-section via the impeller is more than sufficient to ensure a constant flow of the evaporated water molecules . Due to the high speed of the impeller ( 1 ), it is possible to dissipate the heat and condensation that is generated to the cooling medium; the required heat transfer can be increased in this area by means of annular cooling fins ( 14 ).

Further considerations

The height of the annulus ( 4 ) depends on the power to be transferred. Depending on the corresponding wet steam condition, a specific number of steam molecules per unit time occurs per unit area (the inner ring surface). The number of evaporating molecules necessary for the evaporation capacity to be achieved is also easy to calculate, so that the necessary ring area, ie the height of the ring area can be determined from the number of the corresponding molecules. The ring depths of the liquid rings of substance 1 and 2 can be theoretically predetermined or determined empirically. This also applies to the choice of material 2 and ultimately also to the required drive speed in which the diameter of the impeller is particularly important.

It is also important and must be included to what extent the vapor or gas molecules appearing on the liquid ring be absorbed in whole or in part (condense). At only partial absorption must be the height corresponding to that not absorbed portion will be increased.

The total drive power to be used is essentially for the acceleration of the vapor molecules absorbed in the liquid ring and the associated liquid friction within the rotating liquid ring (s), as well as for overcoming the liquid friction within the liquids, including the cooling medium on the outside of the impeller needed. Added to this is the required power consumption of pumps 6, 10 and 19 and the efficiency of the drive unit.

The temperature level of the rotating liquid ring (e) depends on the temperature level of the cooling medium. Depending on the temperature of the  Liquid ring, which, by the way, is only slightly submerged greater than the immersion depth of the gas / vapor molecules to be absorbed it needs to be measured in depth, an ent speaking steam table, different centri required Fugal force exerted on the liquid ring (s) want to act steam molecules.

Because the impeller is essentially constructive consists of a simple rotating body and the required Speed range by means of frequency converter also relative Centrifugal condensers can easily be implemented technically Single and multi-component sensors in the description here NEN construction can be produced relatively inexpensively.

A molecule requires a certain amount of additional kinetic energy to be released from the fluid association. Only this part has to be compensated for by the centrifugal force to be applied (ΔEkin: s = m × r × ω ² , where Ekin is an additional part of kinetic energy, s path, m mass of the molecule, r radius of the rotating liquid ring and ω angular velocity of the liquid ring) .

The smallest finite path or unit of time is required here are, comes to an economically reasonable speed too achieve, in most cases only a multi-component version in question.

In the event of an impinging vapor / gas molecule, however, the full speed vector in the radial direction on the other hand, on the contrary. This be indicates that from a minimum speed the far below the middle theoretically calculable steam / gas molecule speed lies, an immersion in and grasp by the liquid ring are guaranteed.

Claims (1)

Centrifugal condenser as a single or multi-component system, characterized in that a gas or steam is absorbed via a rotating, cooled liquid keitsring in single or multi-component design and is condensed under the influence of the centrifugal force with simultaneous heat dissipation.

• 1. Suitable for the liquefaction of technical gases
• 2. as comb. Compressor / condenser in compression refrigeration circuits, especially for refrigerants and large specific steam volumes. Likewise used in heat pump circuits
• 3. as an evacuation device (vacuum pump)
• 4. as an extraction device for gases