US2947152A

US2947152A - Heat exchanger for separating out constituents from a gas by cooling

Info

Publication number: US2947152A
Application number: US618794A
Authority: US
Inventors: Bloem Aldert Teunis
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1955-11-06
Filing date: 1956-10-29
Publication date: 1960-08-02
Anticipated expiration: 1977-08-02

Description

Aug 2 1960 v A. T. BLOEM 2 HEAT EXOHANGER FOR SEPARATING OUT OONSTITUENTS 947152 FROM A GAS BY COOLING Filed Oct. 29, 195e 1C@ Patented Aug. 2, 1960 HEAT EXCHANGER FOR SEPARATING oUT CoN- sTrTUEN'rs FROM A ons YcooLrNo Aldert Teunis Bloem, Eindhoven, Netherlands, assgnor,

by mesne assignments, to North American Philips Company, Inc., New York, N.Y., a corporation-of Delaware Filed Oct. 29, '1956, Ser. No. 618,794

Claims priority, application Netherlands Nov. 6, 1955 `4 Claims. (ci. 62-40) The invention relates to heat exchangers for separating constituents from a'gas by means of cooling, which heat exchangers are provided with an Kaperture for supplying the gas and an aperture for discharging the gas and a number of projections arranged in the path of the gas, which are mounted on a common supporting member, there being during the operation of the heat exchanger in at least a number .of these projections or groups of projections a decrease in the mean temperature of at the most 20 C. between adjacent projections or adjacent groups of projections, commencing from the hot side to the cold side. The term gas las used herein is to be understood to mean also a vapour or a gas mixture.

Such a heat exchanger may, for example, be used for removingwater Vapour and carbon dioxide from air. This may' be required when `air is to be fractionated or condensed. However, other gases also, for example natdependent of circumstances relating to the iluid itself, that is to say independent of the amount of uid supplied or of the fractions of which it consists.. In this case particularly, according to a further embodiment Vof the invention the supporting member may have one side in heatexchanging contact with a cooling agent contained in a space. This cooling agent may be the working fluid of a refrigerator, for example of a gas refrigerator;

It has also been found that, if4 the heat exchanger must remove water vapour and carbon dioxide from air, it is desirable, according to a further embodiment of the invention, for the part of the heat exchanger intended for the water vapour to be at least substantially horizontal while the part intended for the carbon dioxide extends substantially vertically.

The invention will now be described more fully with reference to some vembodiments thereof.

ural gas, have constituents whichcan be removed-by freezing out; In heat exchangers of this vkind the separa`l tion products accumulate in the heat exchanger, sothat this gets clogged sooner or later.

separation products, for example by heating, the heat exchanger can againbe put in operation. The time required to remove the impurities is vwasted and itis an object of the present invention to provide a design for a heat exchanger of the above-mentioned kind such that compared' with the 'known heat exchanger a larger amount of impurities can be frozen out.

According to the invention, at least a number of the l projections arranged in the path of the gas have a thermal the known heat exchangers in which there is no such temperature difference along the projections. As will be explained more fully hereinafter, this appreciable temperature difference enables a greater -amount of impurities to be stored in the heat exchanger than would be the case without this temperature difference. Preferably, the temperature difference along a projection is not excessively large, for example does no-t exceed 30 C., since otherwise the heat exchanger may occupy too much space. In a structurally simple embodiment, the projections are pins.

The supporting member may be a partition between two spaces in which fluids having different temperatures flow. This is, forrexample, the case when a gas mixture to be fractionated is in heat-exchanging contact with at least one of the fractions produced. However, in certain cases it may be desirable for the amount of thermal energy which is withdrawn from the gas or the gas mixture to be in- After removal of the Fig. 4 ris a cross-sectional view takenalong the line lV-IV of Fig. 3. Y

Fig.v 5 shows a heat exchanger, of which part extends substantially horizontally and part 'substantially vertically.

The heat exchanger shown in Figures 1 vand 2 comprises a supporting member 1 provided-with projections 2, for example pins.

exchanging contact with a; cooling liquid contained in a space 7, for example liquid nitrogen. VThe heat extracted from the gas to be cooled is supplied by way of the pins 2 and the supporting member 1v to the liquid contained in the space 7 so that this liquid evaporates, the vapour be-` ing through a pipe 8 to a refrigerator (not shown) to be re-condensed. The condensate produced by the refrgeator can again be suppliedV to the space 7` through a pipe" 9.v The refrigerator may be a gas refrigeratonbut naturally any suitable refrigerator can be use The supporting member is made from a V'material hav-l ing a thermal resistance such that in'normal operation l there is a mean temperature difference of at the` most" 20 C. between the mean temperatures of the pins 2. yIn' this embodiment, the mean temperature of the series of project-ions 2a is at the most 10 C. higher than`t-hatuof' the series 2b which again is 10 C. higher than that of the series 2, etc. The mean temperature is -t'he'arithmetic mean of the temperature at an end 10 of a projection Vand of 'the temperature at the point A111 at which a projection is attached to the supporting member 1. The tempera" ture difference between these two points in' each projection is at least 5 C. and preferably less than 30 C., inthe embodiment shown, for example, 19 C.

The System oPerates as follows: f.

blower (not shown).

dioxide.

and water is formed. At a Vgiven instant, the air flows past pins having already a very low temperature at their bases, so that the water vapour from the air after being An insulating wall 3y provides` a duct IlV for the gas mixture, the projections `2 being disposed inthe path of the gasmixture. The heat exchanger has an inlet H apertureS land an outlet aperture 6v for the gas `mixture 'to'l be cooled. One end of the supporting member V1 is in heat' condensed on preceding pins freezes to the bases of these pins. However, after some time such an amount of ice 12, which is shown by broken lines in Fig. 1, is frozen to the bases of pins 7 that the air is forced to ilow along the tops of the pins. Consequently, a greater amount of air ilows past these parts of the pins so that a greater amount of thermal energy is supplied to the pins. As a result, part of the ice adhering to the pins melts and the water produced flows down either to be discharged or to be frozen again to the cold lower ends of the pins. The air which flows past the tops of the pins, at a point to the right-hand side of the first-mentioned pins comes into contact with otherpins having a temperature sufficiently lov.y to cause ice to be formed, so that on the upper ends of these pins an amount of ice 13 settles, which is shown by dot-dash lilies in the gures. When the passage at the upper ends of these pins becomes clogged, the air is forced to ow past the lower ends of the pins in this part of the heat exchanger. Only after the passage along these pins also has become blocked, the ice separator is clogged up.

In the part of the ice separator situated further to the right-rand side of the drawing, the carbon dioxide contained in the air can be similarly separated out, if required, provided the pins have a suiciently low temperature.

The heat exchanger shown in Figures 3 and 4 operates on the same principle as described hereinbefore; parts corresponding to those of Figures 1 and 2 are designated by like reference numerals. Here, however, the gas to be. cooled, which is supplied to the heat exchanger through the aperture and leaves through the aperture 6, by way of a supporting member .14 is in heat-exchanging contact with a cold luid which is supplied to the heat exchanger through an aperture 15 and leaves it through an aperture 16. A number of plate-shaped projections ,17 provided with slits |18 are arranged on the member 14. The cold uid which is supplied through the aperture 115 to the heat exchanger ows past projections 19 which Iare 4also attached to the support and thus is in heatexchanging contact with the gas to be cooled. Here also, the thermal resistance of the supporting member 14 is so chosen that there4 is a mean temperature difference of at the most 20 C. between the adjacent projections 17 on which the constituents of the gas are separated out. In addition, during normal operation of the heat exchanger there is a temperature gradient of 5 C. along the length of the projections. This heat exchanger can be used if air to be fractionated must be purified, the air being cooled by heat-exchanging contact with one of the fractions produced in the gas-fractionating system, for example nitrogen. Similarly to what has been described with reference to Fig. l, at the bases of the projections 17 having `a suflciently low temperature ice is formed, part of which subsequently, when the gas mixture is forced to How past the upper parts of the projections, which parts, as has been described herein before, are at a higher temperature, melts olf again. The small amount of water which does not freeze can be drawn olf through small apertures 20.

In the construction shown in Fig. 5, a part 21 in which the water vapour is separated yout is slightly inclined Whereas a part 22, in which the carbon dioxide is separated out, extends vertically. In this embodiment also, the supporting member 1 is in heat-exchanging contact with a lluid having a low temperature which is contained in a space 7. On the member 1 a number of pins 23 which extend to a wall 24 are arranged at an angle to this member; in this embodiment also, the temperature gradient along each pin is at least 5 C. Due to the inclined position of the pins, the effective surface, with the same temperature gradient along a pin, exceeds that of pins arranged at right angles to the support, while the corner at the transition of the parts 21. and 22 can be lled with pins in a structurally simple manner. Generally, it will be undesirable for the part 21 of the heat exchanger in which the water is separated out, to deviate from the horizontal position excessively, in order to prevent. the melting water from collecting on the bottom of the heat exchanger without falling on the ice when dripping olf the pins. Obviously, this dripping Water can be drawn off by the use of a special construction, however, this will generally involve an additional complication of the heat exchanger. There is no such likelihood for the carbon dioxide, but on the contr-ary the gas to be cooled should move vertically in this part of the heat exchanger, so that the carbon dioxide can readily escape on heating.

what is claimed is:

1. A heat exchanger for separating out constituents of a gas by cooling comprising a hollow tube provided with an inlet and outlet for said gas, a strip-like supporting member in said tube, a plurality of projections in said supporting member arranged in the path of said gas and secured to only one interior Wall of said hollow tube, each of said projections taken from the hot side of the tube to the cold side thereof being at lthe most 20 warmer than the next succeeding projection, at least a number of said projections having a thermal resistance such that during operation the ends more remote from the support are at a temperature at least 5 C. higher than the temperature at the points of attachment of the respective projections to said one interior wall, a thermal sink, said supporting member being directly connected to said thermal sink.

2. A heat exchanger as claimed in cla-im 1 wherein said projections are pins.

3. A heat exchanger as claimed in claim 1 further comprising `a conduit adjacent to and in yheat exchanging contact with said hollow tube, and a cooling agent traversing said conduit.

4. A heat exchanger for separating out constituents of a gas by cooling comprising a hollow tube provided with an inlet and outlet for said gas, a strip-like supporting member in said tube, a plurality of projections in said supporting member arranged in the path of said gas and secured to only one interior wall of said hollow tube, each of said projections taken from the hot side of the tube to the cold side thereof being at the most 20 warmer than the next succeeding projection, at least a number of said projections having a thermal resistance such that during operation the ends more remote from the support are at a temperature at least 5 C. higher than the temperature at the points of attachment of the respective projections to said one interior wall, said constituents of the gas to be separated 'out being water vapor and carbon dioxide, the part of the heat exchanger intended for said water vapor being positioned horizontally while the part of said heat exchanger intended for said carbon dioxide extending substantially vertically, a thermal sink, said supporting member being directly connected to said thermal sink.

References Cited in the tile of this patent UNITED STATES PATENTS 1,478,750 McElroy Dec. 25, 1923 1,561,898 Antisell Nov. 17, 1925 1,725,906 Gay Aug. 27, 1929 2,294,137 Spoiford Aug. 25, 1942 2,492,298 Lenning Dec. 27, 1949 2,500,501 Trumpler Mar. 14, 1950 2,585,288 Van Nuys Feb. 12, 1952 2,585,9112 Buschow et al. Feb. 19, 1952 2,663,170 Gloyer Dec. 22, 1953 2,690,060 Legatski Sept. 28, 1956 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,947, l52\ August 2, 1960 Aldert Teunis Bloem It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

ln the heading to the printed specification, line 9, for "Glaims priority, application Netherlands Nov. 6, 1955" read Claims priority, application Netherlands Nov. 5, 1955 Signed and sealed this 25th day of April 1961,

(SEAL) Attest:

ERNEST W SWIDER DAVID L LADD Attesting Officer l Commissioner of Patents