US3851146A

US3851146A - Apparatus for vapor generation

Info

Publication number: US3851146A
Application number: US00289483A
Authority: US
Inventors: F Bennett
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1971-12-15
Filing date: 1972-09-15
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

An apparatus for providing, in a continuous or intermittent manner, a superheated vapor of an organic liquid, such as methylene chloride, for reflowing plastic surfaces or causing a plastic material to flow onto a surface to create a film or coating thereon. The apparatus includes a tubular metal member defining a flow passage for both the liquid and gaseous phases of the liquid being vaporized. A vapor flow control member having a vapor flow orifice is provided at one end of the tubular member while the other end of the tubular member communicates with a source of organic liquid under pressure through an on-off valve. A source of electrical energy is connected in circuit with the tubular member through a switch operated concurrently with the valve whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough. The tubular member is electrically and thermally insulated by a shield and a handle associated with the shield contains the valve and switch.

Description

llnited States Patent 1191 Bennctt APPARATUS FOR VAPOR GENERATION [75] Inventor: Foster C. Bennett, Columbus, Ohio [73] Assignee: The Dow Chemical Company,

Midland, Mich.

[22] Filed: Sept. 15, 1972 [21] Appl. No.: 289,483

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 208,296, Dec. 15,

' 1971, abandoned.

[52] U.S. Cl 219/300, 219/272, 219/308, 219/373, 222/146 HE, 239/136 [51] Int. Cl H05b 1/00, F22b 1/28, B05b 1/24 [58] Field of Search 219/271-276, 219/300, 301, 362, 373, 296-299; 239/133,

I 135, 136, 137, 138; 222/146 HE [56] References 'Cited UNITED STATES PATENTS 383,536 5/1888 5 Newman ..'2l9/300UX 703,970 7/1902 'Ouain 219/300 912,994 2/1909 Comrad 219/300 1,373,809 4/1921 Hadaway 219/300 1,403,594 l/1922 Duo 219/300 1,575,152 3/1926 Di Battista 219/300 UX 2,109,900 3/1938 Cohen 219/300 2,254,680 9/1941 Harvey 219/272 X 2,277,291 3/1942 Blair 219/272 X 2,478,917 8/1949 Haim 219/300 X 2,604,881 7/1952 Masopust 239/136 X 2,641,508 6/1953 Stoner et a1. 239/137 X [4 1 Nov. 26, 1974 2,861,838 5 11/1958 Wyatt et a1. 219/273 2,878,360 3/1959 Tavender et a1..v 239/133 X 3,686,475 8/1972 Mikkola 219/272 3,718,805 2/1973 Posey 219/273 FOREIGN PATENTS OR APPLICATIONS 482,715 4/1938 Great Britain 219/300 13,070 6/1933 Australia 219/271 Primary Examiner-A. Bartis A ttomey, gent, or Firm Glwynn R. Baker [5 7 ABSTRACT An apparatus for providing, in a continuous or intermittent manner, a superheated vapor of an organic liquid, such as methylene chloride, for reflowing plastic surfaces or causing a plastic material to flow onto a surface to create a film or coating thereon. The apparatus includes a tubular metal member defining a flow passage for both the liquid and gaseous phases of the liquid being vaporized. A vapor flow control member having a vapor flow orifice is provided at one end of the tubular member while the other end of the tubular member communicates with a source of organic liquid under pressure through an on-off valve. A source of electrical energy is connected in circuit with the tubular member through a switch operated concurrently with the valve whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough. The tubular member is electrically and thermally insulated by a shield and a handle associated with the shield contains the valve and switch.

2 Claims, 2 Drawing Figures APPARATUS FOR VAPOR GENERATION CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application filed Dec. 15, 1971, Ser. No. 208,296 now abandoned.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a novel apparatus and-a process employing the apparatus for vaporizing fluids, such as volatile organic solvents or mixtures of solvents, to produce superheated vapors of said fluid(s). More particularly, the present invention concerns a pressurized apparatus from which superheated vapors of volatile organic solvents, generated within the apparatus, can be discharged in a controlled manner to impinge against a plastic surface, e.g., coating or surface of a body of plastic, to effectuate the modification of the surface, viz., remove surface imperfections and defects, according to the vapor reflow principle or to flow a plastic powder'on a surface to createa film or coating thereon. I

Several embodiments ofapparatus within the scope of the present invention areillustrated in the Drawings:

charge orifice of the apparatus;

FIG. 2 illustratesanother embodiment of a vaporizer element of the present invention in cross-sectional view, which eliminates the effect of inductance when alternating current is employed.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, having particular reference-to FIG. 1 of the Drawings, there is provided a tubular member which is made ofa metal or an alloy of a metal having a resistance sufficient to convert electrical energy, supplied at low voltage and high amperage, into heat energy at a rate to supply, within a length of several feet, the sensible heat necessary to raise the temperature'of the liquid to the boiling point, the heat of vaporization of theliquid and the heat ofsuperheat of the vapor of the liquid to a prede' termined temperature. Connected to one end 11 of the to ambient atmosphere, as well as electrically insulating tubing 10 is provided with a tubular electrical and heat insulating connector 20. Connector 20 is further connected by piping or flexible tubing 21 to a pressurized container 22 which contains the liquid to be vaporized.

Pressure controls and a source of pressure, neither'of which are shown, are associated with the container '22. The power source 13 is also provided with controls, transformers, and/or rectifiers, etc., as necessary to produce the desired voltage and current to' provide the wattage to produce the desired temperature in the member 10.

The tubular member 10 is preferably provided, as shown, with a fluid flow control valve 23 to permit adjustment of the rate of flow and a simultaneously operable trigger mechanism or valve 24 to-permit off-on flow of fluid through tube 10 as well as an electrical switch which simultaneously permits flow of electricity to the member '10 when fluid is flowing and shuts off the flow 'of electricity to the member 10 when fluid flow is interrupted.

. In operation of the apparatus illustrated in FIG. 1, a volatilizable liquid, for example, a halogenated hydrocarbon such as methylene chloride, is provided in container 22 and the container pressurized with from about 30 to about 200 pounds per square inch air pressure.'The power source is activated, and, for example, if methylene chloride is to be delivered under 30-35 psig. as a superheated vapor at 400F. just outside the nozzle 19, is adjusted to deliver about 30 volts at 75 amperes of alternating current, converted from 220 volt source through an isolated secondary of a transtubular member 10is an electric cable 12 which prov vides one lead from the power source 13. Connected to the other end 14 of the member l'0-is another electric cable 1 5 which provides the second lead from'the' power source 13, thus completing an electric'circuit from the power source 13, to the tubular member 10 (the electrical resistance)- and back to-the power source 13. In the embodiment shown in FIG. 1, the tubula r member 10 is provided with a shielding member l6.which surrounds the member 10 and retains insulation 17 in position to isolate member Whom the shield, thus insulating the member 10 from loss of heat former. Thermocouples, as at points x and y or by trial and error, simplify the adjustmentof the power source to provide a superheated vapor of methylene chloride of a temperature of about 400F.; it being clearly understood the temperature of the vapor inside the apparatus will necessarily be higher than that outside the nozzle due to expansion and cooling phenomena of gases. The apparatus illustrated in FIG. 1 is capable of delivering several gallons an hour of such vapor continuously or intermittently. The preferred embodiment of the apparatus illustrated in FIG. 1' includes the control of the temperature of the member 10 by using the signal generated by the thermocouples x and y to either shut off the current or turn it on intermittently.

It is one advantage of the apparatus of the present invention that once the current is turned off and simultaneously the flow'of fluid is stopped, the member 10 cools rapidly since it is of inconsequential volume, that is, its volume as a heat sink is less than the volume of the liquid in the tube. The apparatus can be even more rapidly cooled by'merely allowing a small quantity of liquid from the container 22 to pass through the member 10 after the current-has been shut off at the transformer controls, for example. Similarly, the member 10 heats up rapidly. Both of these features are important when the liquid being heated is degradable by prolonged contact with high temperature.

3 heating member to eliminate substantially the effect of inductance associatedwith a current flowing through a coil. The tubular member 210 is wound back over itself so that the current flowing at any instant in the inner coil 210A is directly opposite that flowing in the 2108. The outlet end 211 is provided with a nozzel 219 and opposite ends of the coil 210, i.e., 211 and 214, are provided with

electrical connection

212 and 215 which are connected to a power source, not shown. Similarly, the coil 210 is connected at end 214 to a source of liquid not shown. The apparatus may be, in all other aslarly, the coil rnay be employed to heat liquidsor generate vapors for chemical reactions.

' Having described my invention in general, the following examples are set forth to illustrate specific embodiments of the invention.

EXAMPLE 1 A type 316 stainless steel tube having an outside diameter of V4 inch and a wall thickness of 0.028 inch was close wound on a 2 inch mandrel to provide thirteenturns then a spaceequal to about two turns followed by fourteen turns. The coil was started by bringing a point about five inches from one end into a groove in the mandrel near its center, and bringing the tubing to the rear of the mandrel along a groove to the point of beginning of the coil forming section. The coilso wound was insulated between each turn with a disc of insulating material, compressed asbestos, capable of withstanding l,200F. temperatures. The coil was also insulated along and about its peripheral dimensions with an alumina-silica ceramic fiber insulation (e.g., Fiberfrax or Kaowool) of about inch. A 3% inch OD tube of Type 304 stainless steel was placed about the assembly, closed at the rearward end and provided with an end cap to receive the discharge end of the tube and aid in holding the tube within the shield assembly. The shield was provided with a handle of metal to surround the inlet end of the tube. The space between the tube and the handle was insulated. The inlet end of the tube was provided with a fitting to receive a Teflon nipple, to which was fitted a liquid control valve. The leads from a KVA alternating current isolated secondary 220 volt transformer were brazed, oneto the tube and one to the handle. A container provided with an air pressure system was connected to the control valve. Upon pressurization of the container which contained methylene chloride, and activation of the transformer to deliver 30 volts and .75 ,amperes, the methylene chloride flowing into the tube was converted into a vapor which had a temperature, upon leaving thenozzle of about 400F.

The following table illustrates the versatility of the apparatusof FIG. 1 to vaporize various requirements of a methylene chloride composition employed to flow an acrylic paint surface.

Watts at Indicated Ave. Voltage Flow Rate Gallons/Hour 600ll6.5 .1 200/22 moo/27.5 2400/33 Juno/38.5 3600/44 4200/4 with an acrylic lacquer of the type used to paint automobiles and which painted panel had been lightly sanded, removed surface imperfections.

The apparatus illustrated in FIG. 1 can also be operated from a V source using a five KVA transformer 32 volts isolated secondary to supply up to 2 gallons per hour of the methylene chloride composition at 400F.

I claim:

1. An apparatus for converting a volatilizable organic liquid or mixture of liquids into superheated vapors which consists essentially of:

a tubular metal member which is electrically conductive but has a resistance to the flow'of an electrical current and which member defines a flow path for the liquid to be vaporized andfor the vaporized liquid, 7

a vapor flow control member at one end of said tubular metal member, said vapor control member having a vapor outlet orifice, a manually actuated open-close liquid flow control member at the opposite end'of said tubular metal member for selectively controlling liquid flow into said tubular metal member,

a source of electrical energy connected at a pair of spaced points to said tubular metal member by means arranged to be controlled concurrently with and in on-off corresponding relationship with said liquid flow control member whereby electrical energy is causedto flow through a predetermined segment of said tubular metal member to heat the tubular metal member to a temperature to vaporize the liquid flowing therethrough,

a source of volatilizable organic liquid connected in flow communication with the tubular metal member through said liquid flow control member, said source of liquid being under superatmospheric pressure whereby the liquid therein is caused to flow into the tubular metal member when the liquid flow control memberis opened,

the tubular metal member being heated to such a temperature and the length ofthe heated portion of the tubular metal member, the bore of the tubular metal member and the orifice of said vapor flow control member being of such a size relative to each other such that the liquid supplied under pressure into the tubular metal member will vaporize and said'vapor will be heated to above its boiling point at a rate to maintain a pressure of vapor at,

the vapor flow control member sufficient to propel the vapors from the apparatus at least about one foot. I

said means connecting said electrical energy source a connector connecting said tubular metal member through said liquid flow control member to said source of vaporizable organic liquid,

said tubular metal member, vapor flow member, and

said liquid flow control member being capable of withstanding superatmospheric pressures and a temperature of l,200" F. and said electrical energy connectors and switch being capable of withstanding five to ten KVA alternating current power,

said tubular metal member electrically and thermally insulated by a shield and a handle associated with said shield and containing the liquid flow control member and the switch, said vapor control member projecting from one end of the shield.

2. An apparatus for converting a volatilizable organic liquid or mixtureof liquids into superheated vapors which consists essentially of:

a tubular metal member which is electrically conductive but has a resistance to flow of an electrical current and which member defines a flow passage for carrying both liquid and gaseous forms of said liquid to be vaporized,

a vapor flow control member at one end of said tubular metal member having a vapor outlet orifice,

a manually operated open-close liquid flow control member at the other end of said tubular metal member for controlling liquid flow into the tubular metal member,

said tubular metal member being disconnectable and removable from said flow control member,

electrical energy connectors in current flowing contact with the respective ends of said tubular metal member, 7

an electrical current source in circuit with said electrical energy connectors and a switch associated with said liquid flow control member in concurrent similarly functioning open-close relation to said liquid control member for controlling application of energy to said connectors from said source whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough,

a connector associating said tubular metal member through said liquid flow control member to a source of vaporizable organicliquid and means associated with the source for causing the liquid to flow into the tubular metal member when the fluid control member is opened,

said tubular metal member, vapor flow member, and said liquid flow control member being capable of withstanding superatmospheric pressures and a temperature of 1,200F. and said electrical energy connectors and switch being capable of withstanding tive to ten KVA alternating current power,

Claims

1. An apparatus for converting a volatilizable organic liquid or mixture of liquids into superheated vapors which consists essentially of: a tubular metal member which is electrically conductive but has a resistance to the flow of an electrical current and which member defines a flow path for the liquid to be vaporized and for the vaporized liquid, a vapor flow control member at one end of said tubular metal member, said vapor control member having a vapor outlet orifice, a manually actuated open-close liquid flow control member at the opposite end of said tubular metal member for selectively controlling liquid flow into said tubular metal member, a source of electrical energy connected at a pair of spaced points to said tubular metal member by means arranged to be controlled concurrently with and in on-off corresponding relationship with said liquid flow control member whereby electrical energy is caused to flow through a predetermined segment of said tubular metal member to heat the tubular metal member to a temperature to vaporize the liquid flowing therethrough, a source of volatilizable organic liquid connected in flow communication with the tubular metal member through said liquid flow control member, said source of liquid being under superatmospheric pressure whereby the liquid therein is caused to flow into the tubular metal member when the liquid flow control member is opened, the tubular metal member being heated to such a temperature and the length of the heated portion of the tubular metal member, the bore of the tubular metal member and the orifice of said vapor flow control member being of such a size relative to each other such that the liquid supplied under pressure into the tubular metal member will vaporize and said vapor will be heated to above its boiling point at a rate to maintain a pressure of vapor at the vapor flow control member sufficient to propel the vapors from the apparatus at least about one foot, said means connecting said electrical energy source to said tubular metal member including connectors in current flowing contact with the respective ends of said tubular metal member, said electrical energy source being connected in circuit with said connectors and said connecting means further including a switch associated with said liquid flow control member in concurrent similarly functioning open-close relation to said liquid control member for controlling application of energy to said connectors from said source whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough, a connector connecting said tubular metal member through said liquid flow control member to said source of vaporizable organic liquid, said tubular metal member, vapor flow membeR, and said liquid flow control member being capable of withstanding superatmospheric pressures and a temperature of 1,200*F. and said electrical energy connectors and switch being capable of withstanding five to ten KVA alternating current power, said tubular metal member electrically and thermally insulated by a shield and a handle associated with said shield and containing the liquid flow control member and the switch, said vapor control member projecting from one end of the shield.

2. An apparatus for converting a volatilizable organic liquid or mixture of liquids into superheated vapors which consists essentially of: a tubular metal member which is electrically conductive but has a resistance to flow of an electrical current and which member defines a flow passage for carrying both liquid and gaseous forms of said liquid to be vaporized, a vapor flow control member at one end of said tubular metal member having a vapor outlet orifice, a manually operated open-close liquid flow control member at the other end of said tubular metal member for controlling liquid flow into the tubular metal member, said tubular metal member being disconnectable and removable from said flow control member, electrical energy connectors in current flowing contact with the respective ends of said tubular metal member, an electrical current source in circuit with said electrical energy connectors and a switch associated with said liquid flow control member in concurrent similarly functioning open-close relation to said liquid control member for controlling application of energy to said connectors from said source whereby electrical current is caused to flow through the tubular member to heat the member to a temperature adequate to vaporize the liquid flowing therethrough, a connector associating said tubular metal member through said liquid flow control member to a source of vaporizable organic liquid and means associated with the source for causing the liquid to flow into the tubular metal member when the fluid control member is opened, said tubular metal member, vapor flow member, and said liquid flow control member being capable of withstanding superatmospheric pressures and a temperature of 1,200*F. and said electrical energy connectors and switch being capable of withstanding five to ten KVA alternating current power, said tubular metal member electrically and thermally insulated by a shield and a handle associated with said shield and containing the liquid flow control member and the switch, said vapor control member projecting from one end of the shield.