DE1911499A1 - Heat exchanger and cooler - Google Patents

Description

EDWARDLORENCE ^IVI '^

BERNHARD SEIDLER

MARGRIT SEIDLER

LAWYERS

8 Munich 22

Widenmayarstrasse 23 -> Mi-! * -

Telephone (0811) 29 7194 ₀ . M «"

Gaston Maurice MILLE

"Heat exchangers and coolers"

The invention relates to a method for cooling a medium with the help of atomized, cold-generating liquids, heat exchangers and systems provided with these heat exchangers, to put the process into practice.

t -

; Under "cold-generating liquids" are at lower temperatures to understand liquefied gases under atmospheric pressure, for example liquid nitrogen or liquid carbon dioxide.

One of the objects of the invention is as a source of kilogram calories the heat of vaporization of a cryogenic liquid and to use the heat of gases coming from the evaporation of this liquid, with a good thermal output

Another object of the invention is to control the starting temperature of the to be able to regulate the cooled medium precisely by acting on the delivery rate of the cold-generating liquid.

Another object of the invention is to industrially produce a medium at very low temperatures and in a range of high temperatures, for example between 0 ° and -190 ° using [liquid nitrogen to be able to cool.

Furthermore, the invention has set itself the goal of producing cold Medium a liquefied, neutral gas, for example To use nitrogen or carbon dioxide, which reduces the risk of contamination of the cooled medium as a result of accidental loading

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switches off agitation with the refrigerant. This advantage is important for cooling certain sensitive products, e.g. physiological fluids, food products, pharmaceutical products. In the chemical industry, or in the nuclear power industry, a fortuitous event can occur agitation between the cooled liquid and the media, usually used to boost the kilogram calories, bring about chemical reactions or even explosions. For this reason, it is necessary to use double tube heat exchangers, which have a low output, or it must be in a first heat exchanger eil intermediate medium are cooled ", in which there is no risk that it reacts with the medium to be cooled as a result of accidental contact, after which this Intermediate medium is used in a second heat exchanger. The use of kilogram calories of a neutral, liquefied » : th gas according to the present invention as a means of production ' j allows these costly measures to be eliminated.

j ■

I.
According to the method according to the invention, a medium is cooled which circulates in contact with the surface of a heat exchanger wall j, the other surface of this wall being brought into contact with a cold-producing, atomized medium and with the gases resulting from the evaporation of this liquid .

t ^! The atomization of the cold-generating medium, ie the atomization · into a mist of fine droplets, is achieved by pushing the liquid under pressure through small-diameter openings | is thrown. The wall to be cooled is placed opposite these openings and the liquid droplets collide with this wall and evaporate when they come into contact with it.

The atomization increases the contact surface of the liquid and the wall so that the evaporation is sudden and that it is possible will quickly change the caloric output exchanged » change by changing the amount of liquid dispensed * according to the temperature of the cooled medium can be precisely controlled. That of the evaporation of the cold producing medium

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Cold gases originating in contact with the exchanger!

waved away and take in calories for their warming .. The gases burn:

run in countercurrent to the liquid to be cooled, so that a j considerable part of the kilogram calories that is recovered! the heating of the gases between the evaporation temperature of the " Liquid and corresponds to a temperature that is in the vicinity of the inlet temperature of the medium to be cooled. ;

According to one feature of the invention, there is a heat exchanger for industrial application of the process of parallel arranged elements, each element of three concentric Pipes. The center tube is at one of its ends with a source of cryogenic liquid under an actual Connected pressure, which is between two and ten bar. The other end of the tube is closed and part of the circumference The tube is provided with small-diameter openings through which the cold-generating liquid is atomized.

; The intermediate pipe is the heat exchanger pipe. It is on one; ! Its ends are open for the exhaust gases to escape. The outer pipe! Is thermally insulated and the medium to be cooled runs between the two ends in a direction opposite to the direction of flow of the exhaust gases. The heat exchanger tube consists of a ^{metal that conducts heat 1} well, for example copper or stainless steel. Preferably, cooling fins made of the same metal are in; Helical shape attached to the inner and outer walls of the heat exchanger tube. In order to improve the atomization, each opening of the central tube can be equipped with an atomizing nozzle of a known model.

According to a further feature of the invention, there is a second type an exchanger for the industrial application of the process described from a cryostat, i.e. a double-walled vessel

with an interposed vacuum. This vacuum amounts to • -P h.

jaxf at least 10 torr and preferably to 10 torr. The cryostat is preferably of the type that is insulated in the best possible way, i.e. that its inner wall is provided with a shield, which reflects heat radiation. The cryostat consists of two

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«Ν Ij. mm

; closely coupled, independent parts, the coupling is done with the help of two paddles and a clamp.

; The cryostat consists of a central cavity that is connected to the j ; Outside air is connected by a throat. i

A channel is arranged along the axis of this central cavity, which is closed at one of its ends with a stopper, while the other end with a pressurized one ■ is connected to the source of a cryogenic liquid. Part i of the length of this channel is small-diameter openings provided, through which the cold-generating liquid is atomized.

The medium to be cooled circulates in a queue which is arranged in the cavity of the cryostat.

'. According to one feature of this heat exchanger, this cooling

j snake made up of two parts arranged in series. The first of these Parts in the direction of circulation of the medium consist of not closely spaced Spirals arranged in an annular space leading from the inner wall of the cryostat and a circular one Shielding is limited. The remaining gases from the evaporation of the cryogenic liquid run in this space between the coils of the cooling coil before they escape through the neck of the cryostat.

j The second part of the cooling coil consists of seamlessly joined-I lying spirals, which are arranged in a continuous area around the part of the central channel which is pierced by the atomizing orifices. The cold-producing, vaporized liquid-I Speed is thrown against the half-periphery of the cooling coil, which is oriented towards the center and evaporates in contact with ider cooling coil.

: According to a feature of the invention, the surface part system, the total is the first '■ of the cooling coil between four to six times a surface of the second part of the cooling coil!.

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_5 - "191U99

According to a further feature of the invention, a device for cooling a medium according to the method described comprises in combination a storage container with a cold-producing liquid, an auxiliary buffer container of poor fit, means for transferring the cold-producing liquid into the buffer container j, means to keep the cryogenic liquid in the \

ι to keep the buffer tank at a constant pressure of between {! two and ten bar, a heat exchanger cooler of one! !, of the types described above, an insulated channel \ connecting the buffer vessel with the central channel of this heat exchanger and a discharge amount regulator slide of a type; can work at the temperatures of the cold-generating liquid and which is introduced into this line, the opening of which through! ; an electronic device with derivative, proportional and integral action is modulated, controlled by a temperature sensor placed on the cooling coil at the exit of the heat exchanger.

The means to keep the cryogenic liquid in the buffer tank under pressure consist of, for example a refrigerant-conveying pump immersed in the storage tank and is automatically controlled by a pressostat located on the buffer container.

Further features and advantages of the invention emerge from the following description of a schematic in the attached Drawings illustrated embodiment,

Fig. 1 is a sectional view of an exchanger element,

Fig. 2 is a sectional view of one loaded into a cryostat Heat exchanger, and

Fig. 3 is a schematic view of a cooling device.

The heat exchanger element shown in Fig. 1 consists of three concentric tubes.

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j The central tube 1 of small diameter is with its lower End connected to a source of pressurized cryogenic liquid. This pipe is on at least one part pierced its length by openings 4 small diameter, through which the cryogenic liquid is atomized. The end of the tube is closed.

The intermediate tube 2 is the heat exchanger tube from a heat good conductive material. It is closed at its lower end 6-:

^! sen. Its upper end 7 is open to the remaining gases from;

■ to let go of the evaporation of the refrigerating ί Liquid originate. :

On the inner and outer walls of the tube 2, ribs made of a metal that conducts heat well are attached in the form of screws. The purpose ; these ribs is to increase the exchange surface to slow the exit velocity of the residual gases and by ^": run length to increase the medium to be cooled. ]

The outer tube 3 is provided with insulation 11 on the outside. ί It is closed at both ends and at its top ^! End connected to a supply line 8 for the medium to be cooled »At the lower part, the cooled medium flows off through the discharge line 9. This exchanger element works as follows:

The cold-generating liquid is introduced into the central pipe 1 and onto the inner walls of the intermediate pipe 2 in the form of a A mist of fine droplets is thrown up.

It evaporates in contact with these walls and receives its heat of evaporation from the medium to be cooled through the wall of the heat exchanger tube. The residual gases heat up as they circulate in contact with the wall of the exchanger tube. The gases and the medium to be cooled circulate in the opposite direction of flow. If the necessary cooling capacity is greater than the capacity of an exchanger element, several elements are connected in parallel and the central pipes are connected to a common

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seed collectors connected. Likewise, the supply lines 8 and Ab- j

lines 9 of the medium to be cooled connected to two collectors, j

A discharge regulator slide is in the supply line for the cold I

arranged liquid and its opening is through a ^;

electronic device changed by a temperature;

sensor is controlled, which is in the outlet of the cooled medium; is introduced.

Fig. 2 shows a second embodiment of a heat exchanger, which should be preferred for its better insulation, which greatly reduces the loss of calories through the walls. ■

A cryostat of a known model consists of two walls, an outer wall 2 and an inner wall 1J, between which

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a vacuum is established which is between 10 Torr and 10 Torr.

! This cryostat is of a very well insulated type, i.e. that the outer surface of the wall 13 is covered with a reflective screen: ii4 is clad, which is intended to block the heat radiation ! to shield.

This cryostat has the general shape of a cylindrical bottle ^ with an open neck.

It consists of two parts, each of which has its own sealed Forms space. These two parts are connected by two flanges 15 and 16 which are welded onto the two walls ι are. The flange 16 has a groove 17 in which a round Sealing ring 18 is introduced. The two flanges are held in close contact by a collar 19 which extends to the outer conical surface of the flanges.

An adsorbent product 20 is placed between the two walls • inserted in contact with the inner wall. The function of this product is to maintain the vacuum by keeping the molecules open adsorbed, which originate from the degassing of the walls.

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Ϊ91Μ99

Two valves 21 and 22 are arranged on each of the parts of the cryostat, to avoid bursting if there is an abnormal ■ increase in pressure. These valves serve at the same time to the Connect the vacuum pump. Annular Pretten 23 are around the Perimeter of the cryostat arranged.

The bottom of the cryostat is curved and rests with its periphery on a flat support 24.

A channel 27 is arranged along the axis of the cryostat. It is closed at the lower end and with a at the upper end Source of a pressurized cryogenic liquid connected. In addition, they are thermally insulated. It consists for example wise up to the level of a horizontal partition 28 made of a double-walled tube with a vacuum in between.

j The part of the line 27 that is under the horizontal partition 28 is pierced by openings 29 of small diameter, through which the cold-generating liquid is atomized.

The medium to be cooled penetrates the cryostat through the neck through the line 30 and out again through the line 3I.

Three cooling coils are arranged in an annular space, one from the inner wall of the cryostat and one circular Shield 33 is limited. These three snakes are parallel connected to line 30 by a collector. The three cooling coils are arranged in three layers of different diameters. The spiral circumferences are not directly adjacent to one another. Those resulting from the evaporation of the cryogenic liquid Gases circulate upward between the spiral passages and exit through the throat opening.

Each of the three serpentines is extended by a second part which is formed from closely spaced spirals 34, the are arranged according to screws of the same diameter, which surround the lower end of the tube 27, which is provided with atomization openings

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I is provided. j

! On the upper part the three cooling coils are parallel through one

! Collector 35 connected to output line 3I. A warmth!

ι sensor 36, for example a thermocouple, is on the collector 35 ■

ι arranged, which corresponds to the zone where the temperature of the to:

cooling medium is lowest. ·. j

The cross section of the cooling coil is dependent on the Ab- j : amount of medium to be cooled and the number of parallel:

! mounted cooling coils selected so that the medium swirls in the; ^; Circulates inside the snake at a speed that is higher _:

is than 2 meters / second. ;

' With such a heat exchanger, the one with liquid nitrogen
j is working, an exchange coefficient per square meter of the exposed surface of the cooling coil and per hour of 2,200 kilocalories was measured in the zone that was in the gaseous
Phase works and equals 22,000 kilocalories in the zone that ^{: is} in the liquid phase. This zone is the most effective
Exchange surface of the cooling coil equals half of the total surface, since only half of the tubes are centrifuged
Receives drops of liquid. Experience shows that
The best overall result is achieved when the overall refrigeration capacity
i of the heat exchanger in two equal parts between the zone in
! gaseous and liquid phase is divided. The surface of the cooling coils, which are in the annular space in the
gaseous phase are introduced is equal to about 50 times
the total surface of the cooling coil, which is arranged inside the annular shield 33. In practice the j ratio of the surfaces is between 40 times and 60 times.

The flow cross-section of the gases around the coils of the cooling coil; in the annular space is calculated so that the gases swirl i

circulate at a speed greater than 6 meters per j Second for normal functioning of the heat exchanger. A stacking of perforated shields 37 is

Sn a p. <% q / 1 i λ ι
% 7 ⁿ JU f ^ iJ »y I 5 5 4

j placed over the neck to hold the tubes and the discharge

■ to slow down the speed of the residual gases.

The arrangement of the cryostat in two parts makes it possible to introduce internal devices in the lower part of the cryostat, which is then covered with the upper part. The maintenance work can be carried out in the interior of the cryostat, to destroy the vacuum in the two halves without \. ;

: Pig. J5 schematically represents the entirety of a cooling system in a? special embodiment for clarifying wine.

The whole of the system consists of a reservoir 44 containing liquid nitrogen at atmospheric pressure. In ^; j this nitrogen is a pump 45 of a known model ^; submerged, which is suitable for use at a temperature of -195 °; to work.

This pump pushes the liquid nitrogen into a buffer container 46 small size; one arranged on this container

j Pressostat 47 controls the start and stop of the pump ; and maintains an actual pressure of the order of magnitude in the container of 5 bar upright.

^; The buffer tank 46 is connected to the central channel of the heat from t he c of r 42 by a heat-insulated conduit, for example a tube having a double coat and ■ ■■ dazwischengeschaltetem vacuum. A

■ Discharge regulator slide 48 of a type that varies with temperature

If liquid nitrogen can work is on these sewers

arranged.

The opening of this slide is regulated by a device 49, which is controlled by the temperature sensor 50 introduced into the heat exchanger.

This type of regulation is well known. The heat sensor is of a type that converts temperature into voltage, such as a thermocouple. The device 49 is an electronic one

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i device comparable this voltage with a reference voltage <similar to the desired set output temperature; is equivalent to. The tension difference is increased. When the ■ slide 48 is pneumatic, the voltage difference acts

! a pressure transducer with derived, proportional and integral : gral effect that modulates the opening of the regulator slide 48.

^: A derivative from the slider 48 connected to an electric slider 51; is provided, allows the heat exchanger to be quickly

[drove to bring.

The device illustrated by Figure 3 is one embodiment for clarifying wine.

It is known that the tartaric acid contained in wine precipitates when the temperature drops. In case of Sparkling wines, especially champagne, it is necessary because the bottles cannot be uncorked before consuming the wine; to cool near freezing temperature before bottling.

The wine is in a container 40 at ambient temperature. It is pumped by a pump 41 and after it has passed through the Heat exchanger has flowed, it is received in a container 4j5.

At the control device 49, a temperature is set that is slightly higher than the freezing temperature of the wine, for example 1/10 degree higher. The tests carried out show that a temperature of the wine is reached at the outlet of the exchanger which is very stable, with the deviations below I / JO degrees lie.

The advantages of the invention are as follows:

: The installation costs of a cooling device are in relation to i those of the known cooling machines are low.

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The maintenance costs are very low.

It is possible to cool at very low temperatures and the The same device makes it possible to work in a very wide temperature range, for example from 0 ° to -190 °, namely ■ j with liquid nitrogen. This advantage is important for the in-! direction of research laboratories. It allows a circulating medium to be exposed to considerable thermal shocks.

If, as a cryogenic liquid neutral, liquefied _gases: be used, such as nitrogen or carbon dioxide, may be any circulate medium to be cooled directly in the heat exchanger without its pollution is possible as a result of accidental contact with the coolant. The cooling capacities per surface unit are high, which makes it possible to manufacture heat exchangers of small size. The systems are noiseless and clean and can be set up directly at the work site.

ί As a result of the speed of the heat exchange in the zone in the liquid phase, it is possible to act very quickly on the outlet temperature of the medium in which the amount of cold-generating liquid is regulated. This results in a very precise temperature regulation option, which opens up special application possibilities, such as the clarification of wine.
i

! If the heat exchanger is fed with liquid nitrogen, it is for certain areas of application, such as the

j Cold, food or physiological preservation Liquids possible to use the residual gases as a neutral atmosphere into which the cooled products are introduced, which improves their conservation.

With a heat exchanger of the cryostat type operating with liquid nitrogen at an actual pressure of 5 kg / qua- [ three inches was peened and when cooling, a medium on; a temperature of -20 °, carried out tests have shown

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j that the cooling capacity is 80 kilogram calories (kilofrigories) each [Liters of liquid nitrogen was.

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Claims (1)

191H99 -14 claims: \) Method for cooling a medium circulating in contact with the surface of a heat exchanger wall, since the mark denotes that the other surface of the wall | j by an atomized, pressurized cold-generating plus! The liquid and the residual gases resulting from the evaporation of this liquid are cooled. ^: : 2. Heat exchanger-cooling device for the practical transit \ carrying out the method according to claim 1 of parallel zusammenge- I: untranslated elements, characterized in that each element of; consists of three concentric pipes, a central pipe which is closed at one of its ends and connected to a source of pressure - = 1 of the refrigerating liquid on the other side - and is provided on part of its length with openings of small diameter through which the cryogenic liquid decomposed \ atomises and that a Zwischenaustauscherrohr present, | which is open at one of its ends, as well as an outer, insulated pipe in which the medium to be cooled circulates. 3. Heat exchanger cooling element according to claim 2, characterized characterized in that cooling fins in helical form made of a metal that conducts heat well on the inner and outer walls of the exchanger tube are arranged. 4. Heat exchanger cooling device for practicing the method according to claim 1, characterized in that it consists of a cryostat having an opening and that a line is arranged along the axis of the central cavity of the cryostat, which is closed at the end that which is connected at the other end to a source of the cold-producing, pressurized liquid and is provided over part of its length with openings of small diameter through which the cold-producing liquid is atomized and that a heat exchanger base is present in which the medium to be cooled 909839/1 1 1 1 BATH ORIGINAL 191U99 running around, with this snake in the central recess of the cryostat is arranged around the aforementioned central line. 5. Heat exchanger cooling device according to claim 4, characterized in that the cryostat and its opening are circular has the shape of a neck and that it consists of two parts, each of which forms a space that is a double, tight wall with an intervening vacuum of at least 10 torr, and that these two parts are tightly sealed and Way are coupled with the help of two at their opposite ends welded flanges, which by a Covenant are kept in contact with each other. 6. Heat exchanger cooling device according to claim 4, characterized in that the cooling coil consists of two parts lying in series, a first part which is located at the end where the medium to be cooled arrives and which consists of spiral circumferences that are not closely adjacent, which are housed in an annular space which is delimited by the inner wall of the cryostat and a wall and in which the residual gases circulate and one ^; second part, which is arranged ani at the outlet end for the cooled medium and which consists of tightly fitting spiral turns | 'The same diameter is formed, which are arranged around the end of the central tube which is provided with the atomization openings. j 7. The heat exchanger-cooling device according to claim 6, characterized in ¹ that the surface of the first part of the cooling. snake between ko times undöO times the total surface of the ', second part of the cooling coil. 8. Device for cooling a medium according to the method according to claim 1, characterized in that they in combination comprises a reservoir containing a cryogenic liquid at atmospheric pressure, a buffer tank small size, means for transferring the cold-generating liquid into the buffer tank, facilities to keep the actual 9 0 9 8 3 9/1111 -Ιοί neuter pressure in the buffer tank between 2 and 10 bar j hold a heat exchanger cooling device of the in claim 2 to i 7 described type, an insulated line, which the Pufferbe-ι tank connects to the central pipe of this heat exchanger, one jn j I : Regulating slide for the delivery amount in this line, whose open ι tion is effected by a control device that is operated by an am j The output of the cooled medium from the heat exchanger arranged heat sensor is controlled. : 9 · Application of the method according to claim 1 for cooling , a medium that is at risk of deterioration through accidental contact with ordinary cooling media is characterized in that the Kaite-producing, atomizing, the liquid is a liquefied, neutral gas. 10. Application of the method according to claim 1, in order to preserve perishable food due to iKälte, characterized in that, that the atomized cold-generating liquid is liquid nitrogen and the gaseous residual nitrogen as neutral Atmosphere is used in which the preserved foods are introduced. 11- Application of the method according to claim 1 for clarifying sparkling wine, characterized in that the wine with a _s . i Temperature is cooled, which is higher by 1/10 of a degree takes place as its freezing temperature and the ses cooling by circulating in contact with a cooled by a cryogenic liquid atomized wall. 909839/1111