US1995361A - Surface condenser - Google Patents

Surface condenser Download PDF

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US1995361A
US1995361A US701780A US70178033A US1995361A US 1995361 A US1995361 A US 1995361A US 701780 A US701780 A US 701780A US 70178033 A US70178033 A US 70178033A US 1995361 A US1995361 A US 1995361A
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steam
wall
heat
condensing
condensed
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US701780A
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Wesley M Nagle
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/04—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by preventing the formation of continuous films of condensate on heat-exchange surfaces, e.g. by promoting droplet formation

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  • This invention relates to heat interchange apparatus, such as surface condensers, in which vapor is condensed by the transfer of heat to a cooling fluid through a wall interposed there between. It is the object of the invention to improve the efficiency of such apparatus.
  • the vapor condenses upon the wall which separates it from the cooling fluid and wets the wall so that a thick layer of condensate always is present upon the condensing surface, that is, the surface of the wall adjacent the vapor,
  • This thick layer of condensate insulates the condensing surface and seriously limits the condensing capacity of. the apparatus, namely, limits the amount of vapor that may be condensed per unit time with a unit area of condensing surface and with a given difference in temperature between the vapor and the cooling fluid.
  • the present invention contemplates a method of treating the condensing surface of apparatus of this general type to modify the condensing surface substantially permanently so that it is not wetted by the condensate and so that the latter is caused to gather together in the form of drops on the condensing surface, leaving a substantial fraction of the condensing surface directly exposed to the vapor andavailable for effecting heat transfer at a maximum rate.
  • the condensing surface is treated to leave a thin film of an agent which has the ability to cling tenaciously to the condensing surface and not be washed away by the normal action of the vapor or its condensate and which is non-wet- -table by the condensate.
  • the treating agent is used in such quantity as to form an extremely thin adsorbed film upon the condensing surface so as not to introduce a substantial additional thermal resistance.
  • the drop-wise condensation efiected in accordance with the invention increases several times the individual coefficient of heat transfer from condensing steam to a solid surface expressed as the quantity of heat transfer per unit time per unit surface area. per unitdifierence in temperature between and the condensing surface.
  • agents containing compounds having one or more non-polar parts or hydrocarbon radicals attached to an active polar group are capable of promoting lasting drop-wise condensation of steam when the compound is applied on' metals of moderate smoothness.
  • the polar group of these compounds probably causes the compound to adsorb on the 55 surface of the metal or form an insoluble comthe steam pound with the metal while.
  • the hydrocarbon group probably serves to render the metal surface non-wettable to water.
  • Entirely non-polar compounds, such as the parafiin hydrocarbons do not cling tenaciously to the surface of the metal and, consequently, are not suited for promoting drop-wise condensation.
  • the higher fatty acids such as'oleic, stearic and palmitic acids, are well suited for promoting lasting drop-Wise condensation of steam on moderately .smooth tubes of copper, brass, admiralty metal, Monel metal, nickel and chrome-nickel steels. Fats and waxes which contain the higher fatty acids may also be used.
  • Organic compounds containing bivalent sulphur, such as the xanthates, dithiophosphates and mercaptans,. are well suited for promoting drop-wise condensation of steam on copper and copper alloys, such as brass and Monel metal. Particularly.
  • the treating agent may be applied by rubbing the condensing surface with a cloth moistened with the agent or with a solution of the agent in a suitable solvent or by introducing the agent or its solution into the steam chamber as a spray or vapor.
  • the agent may be applied by washing the steam chamber with a solution or an emulsion of the treating agent. If the condensing surface is rough it should be made moderately smooth by grinding or bufiing.
  • the treating agent may be applied subsequent to the smoothing operation or the two operations may be combined by mixing the treating agent with the abrasive.
  • the single figure of the accompanying drawing is a detail fragmentary sectional view of one wall of a surface condenser which separates the vapor to be condensed and the cooling fluid.
  • the surface of the wall 10 adjacent the vapor to be condensed is providedwith an adsorbed film 11 of any one of the treating agents above mentioned.
  • the film 11 is united to the surface of the wall 10 by a bond, 'as indicated at 12, which probably is brought about by a union between the treating agent and the metal to form an insoluble compound.
  • a heat interchange apparatus in whicl i vapor is condensed by the transfer of heat'to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said vapor condenses has a thin adsorbed film of a material which clings tenaciously to the wall and resists removal by the normal action of said vapor and its condensate and is nonwettable by said condensate.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of an organic compound having a non-polar part attached to a polar partand capable of clinging tenaciously to said surface and which is nonwettable by water.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a compound selected from the group which consists of fatty acids and organic compounds containing bivalent sulphur, said compound con-1 taining a non-polar part and a polar part.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a fatty acid.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a dithiophosphate.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a mercaptan.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fiuid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a higher fatty acid.
  • a heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of an organic compound containing bivalent sulphur, said compound'containing a non-polar part and a polar part.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Description

March 26, 1935. w. M. NAGLE SURFACE CONDE NSER Filed Dec. 11, 1933 Patented Mar. 26, 1935 UNITED STATES PATENT OFFICE 18 Claims.
This invention relates to heat interchange apparatus, such as surface condensers, in which vapor is condensed by the transfer of heat to a cooling fluid through a wall interposed there between. It is the object of the invention to improve the efficiency of such apparatus.
In apparatus of this general character the vapor condenses upon the wall which separates it from the cooling fluid and wets the wall so that a thick layer of condensate always is present upon the condensing surface, that is, the surface of the wall adjacent the vapor, This thick layer of condensate insulates the condensing surface and seriously limits the condensing capacity of. the apparatus, namely, limits the amount of vapor that may be condensed per unit time with a unit area of condensing surface and with a given difference in temperature between the vapor and the cooling fluid.
The present invention contemplates a method of treating the condensing surface of apparatus of this general type to modify the condensing surface substantially permanently so that it is not wetted by the condensate and so that the latter is caused to gather together in the form of drops on the condensing surface, leaving a substantial fraction of the condensing surface directly exposed to the vapor andavailable for effecting heat transfer at a maximum rate. Thus, the condensing surface is treated to leave a thin film of an agent which has the ability to cling tenaciously to the condensing surface and not be washed away by the normal action of the vapor or its condensate and which is non-wet- -table by the condensate. The treating agent is used in such quantity as to form an extremely thin adsorbed film upon the condensing surface so as not to introduce a substantial additional thermal resistance. The drop-wise condensation efiected in accordance with the invention increases several times the individual coefficient of heat transfer from condensing steam to a solid surface expressed as the quantity of heat transfer per unit time per unit surface area. per unitdifierence in temperature between and the condensing surface.
It has been discovered that agents containing compounds having one or more non-polar parts or hydrocarbon radicals attached to an active polar group are capable of promoting lasting drop-wise condensation of steam when the compound is applied on' metals of moderate smoothness. The polar group of these compounds probably causes the compound to adsorb on the 55 surface of the metal or form an insoluble comthe steam pound with the metal while. the hydrocarbon group probably serves to render the metal surface non-wettable to water. Entirely non-polar compounds, such as the parafiin hydrocarbons, do not cling tenaciously to the surface of the metal and, consequently, are not suited for promoting drop-wise condensation. The higher fatty acids, such as'oleic, stearic and palmitic acids, are well suited for promoting lasting drop-Wise condensation of steam on moderately .smooth tubes of copper, brass, admiralty metal, Monel metal, nickel and chrome-nickel steels. Fats and waxes which contain the higher fatty acids may also be used. Organic compounds containing bivalent sulphur, such as the xanthates, dithiophosphates and mercaptans,. are well suited for promoting drop-wise condensation of steam on copper and copper alloys, such as brass and Monel metal. Particularly. good results have been obtained with potassium amyl, xan thates, potassium ethyl xanthates, amyl mercaptans and benzyl mercaptans. In general, those compounds of the classes of organic compounds above mentioned which contain the so-called larger hydrocarbon radicals are more effective in promoting drop-wise condensation than those which contain the smaller hydrocarbon radicals.
The treating agent may be applied by rubbing the condensing surface with a cloth moistened with the agent or with a solution of the agent in a suitable solvent or by introducing the agent or its solution into the steam chamber as a spray or vapor. The agent may be applied by washing the steam chamber with a solution or an emulsion of the treating agent. If the condensing surface is rough it should be made moderately smooth by grinding or bufiing. The treating agent may be applied subsequent to the smoothing operation or the two operations may be combined by mixing the treating agent with the abrasive.
The single figure of the accompanying drawing is a detail fragmentary sectional view of one wall of a surface condenser which separates the vapor to be condensed and the cooling fluid. As illustrated, the surface of the wall 10 adjacent the vapor to be condensed is providedwith an adsorbed film 11 of any one of the treating agents above mentioned. It will be noted that the film 11 is united to the surface of the wall 10 by a bond, 'as indicated at 12, which probably is brought about by a union between the treating agent and the metal to form an insoluble compound. The vapor to be condensedcondenses upon the surface of the film 11 inthe form of drops 13 which roll off without wetting the film 11 and leave numerous areas 14 directly exposed to the vapor.
The following is illustrative of the advantages of the invention. When condensing saturated steam on a clean nickel tube in a small falling film condenser the over-all coeflicient of heat transmission was found to be 456 B. t. u. per square foot, per hour per degree Fahrenheit difference between the temperatures of the steam and the cooling water but when the tube was treated with oleic acid drop-wise condensation resulted and the over-all rate of heat transfer rose to 950. Had the thermal resistance through the tube and on the cooling water side of the tube been less than what was employed, the gain in condensing efiiciency would have been even more striking.
Using an apparatus treated in accordance with the invention I have secured drop-wise condensation of steam at thermal current densities many fold that obtained in a typical surface condenser in a power plant. In the above example, the thermal current density was 135,000 British thermal units per hour per square foot of condensing surface.
I claim: v
1. The method of improving the condensing efficiency of heat interchange apparatus in which vapors are condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the vapors contact a film of a material which has the property of tenaciously resisting removal by the normal action of said vapor and its condensate and is non-wettable by said condensate. y
2. The method of improving the condensing efficiency of heat interchange apparatus in which steam is condensed bythe transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of an organic compound having a non-polar part attached to a polar part and capable of clinging tenaciously to said surface and which is nonwettable by water.
3. The method of improving the condensing efllciency of heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of a compound selected from the group which consists of fatty acids and organic compounds containing bivalent sulphur, said compound containing a non-polar part and a polar part.
4. The method of improving the condensing efficiency of heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of a fatty acid.
5. The method of improving the condensing efliciency of heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of a dithiophosphate.
6. The method of improving the condensing efficiency of heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of a mercaptan.
7. A heat interchange apparatus in whicl i vapor is condensed by the transfer of heat'to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said vapor condenses has a thin adsorbed film of a material which clings tenaciously to the wall and resists removal by the normal action of said vapor and its condensate and is nonwettable by said condensate. i
8. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of an organic compound having a non-polar part attached to a polar partand capable of clinging tenaciously to said surface and which is nonwettable by water.
9. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a compound selected from the group which consists of fatty acids and organic compounds containing bivalent sulphur, said compound con-1 taining a non-polar part and a polar part.
10. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a fatty acid.
11. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a dithiophosphate.
12. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a mercaptan.
13. The method of improving the condensing efficiency of heat interchange apparatus in which steam is condensed bythe transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of a compound selected from the group which consists of the higher fatty acids and organic compounds containing bivalent sulphur, said compound containing a non-polar part and a polar part.
14. The method of improving the condensing 'eificiency of heat interchange apparatus in which compound containing a non-polar part and a polar part.
16. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fiuid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of a higher fatty acid.
17. The method of improving the condensing efiiciency of heatinterchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween which comprises forming upon the surface of said wall with which the steam contacts a film of an organic compound containing bivalent sulphur, said compound containing a nonpolar' part and a polar part.
18. A heat interchange apparatus in which steam is condensed by the transfer of heat to a cooling fluid through a wall interposed therebetween wherein the surface of said wall upon which said steam condenses has a thin adsorbed film of an organic compound containing bivalent sulphur, said compound'containing a non-polar part and a polar part.
WESLEY M. NAGLE.
US701780A 1933-12-11 1933-12-11 Surface condenser Expired - Lifetime US1995361A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2469729A (en) * 1945-12-28 1949-05-10 Atlantic Refining Co Heat exchange method for the dropwise condensation of vapors
US2919115A (en) * 1956-05-15 1959-12-29 Griscom Russell Co Impregnated porous condenser surfaces
US3125866A (en) * 1964-03-24 Refrigerator with water repellent wall
US3167927A (en) * 1961-06-23 1965-02-02 Carrier Corp Promotion of dropwise condensation
US3186476A (en) * 1961-04-14 1965-06-01 Asahi Chemical Ind Method for heating liquid by means of steam
US3861872A (en) * 1973-04-02 1975-01-21 Sybron Corp Steam sterilizer
US3861873A (en) * 1973-04-02 1975-01-21 Sybron Corp Steam sterilizer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3125866A (en) * 1964-03-24 Refrigerator with water repellent wall
US2469729A (en) * 1945-12-28 1949-05-10 Atlantic Refining Co Heat exchange method for the dropwise condensation of vapors
US2919115A (en) * 1956-05-15 1959-12-29 Griscom Russell Co Impregnated porous condenser surfaces
US3186476A (en) * 1961-04-14 1965-06-01 Asahi Chemical Ind Method for heating liquid by means of steam
US3167927A (en) * 1961-06-23 1965-02-02 Carrier Corp Promotion of dropwise condensation
US3861872A (en) * 1973-04-02 1975-01-21 Sybron Corp Steam sterilizer
US3861873A (en) * 1973-04-02 1975-01-21 Sybron Corp Steam sterilizer

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