US3762893A

US3762893A - Submerged direct contact vaporization process

Info

Publication number: US3762893A
Application number: US00135197A
Authority: US
Inventors: L Larsen
Original assignee: Chicago Bridge and Iron Co
Current assignee: Chicago Bridge and Iron Co
Priority date: 1971-04-19
Filing date: 1971-04-19
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

Vaporizing a liquefied gas by feeding the hot products of combustion of a combustible material into and below the surface of a mass of the liquefied gas in a tank, said liquefied gas being at a temperature at which at least water in the hot products of combustion is solidified, removing from the tank unsolidified products of combustion in admixture with the vaporized gas formed by heat exchange between the hot products of combustion and the liquefied gas and at least periodically removing from the tank solidified water.

Description

United States Patent 1 1 Larsen 1 1 Oct. 2, 1973 1 1 SUBMERGED DIRECT CONTACT VAPORIZATION PROCESS [75 I Inventor: Lyle Vernon Larsen, Naperville,

lll.

[ 73 Assignee: Chicago Bridge & Iron Company, Oak Brook, 111.

[221 Filed: Apr. 19, 1971 211 Appl. No.: 135,197

[52] US. Cl 48/190, 48/196 R, 62/52, 261/77, 261/123 [51] Int. Cl Fl7c 7/02, Fl7d 1/04 [58] Field of Search 48/190,196 R, 196 VS; 62/52 US, 50 US; 23/281 [56] References Cited UNITED STATES PATENTS 3,431,743 3/1969 Green ..62/52 2,463,098 3/1949 Goddard 48/61 3,413,810 12/1968 Kaufmann. 50/261 X 3,524,319 8/1970 Stockel 60/261 UX 2,921,004 1/1960 Wood 126/350 X 3,107,482 10/1963 FOnO 60/39.]6 R 3,088,812 5/1963 Bitterlich et all. 23/281 FOREIGN PATENTS OR APPLICATIONS 1,158,934 7/1969 Great Britain 48/190 Primary Examiner-Joseph Scovronek AttorneyMerriam, Marshall, Shapiro & Klose 57 ABSTRACT Vaporizing a liquefied gas by feeding the hot products of combustion of a combustible material into and below the surface of a mass of the liquefied gas in a tank, said liquefied gas being at a temperature at which at least water in the hot products of combustion is solidified, removing from the tank unsolidified products of combustion in admixture with the vaporized gas formed by heat exchange between the hot products of combustion and the liquefied gas and at least periodically removing from the tank solidified water.

7 Claims, 1 Drawing Figure PATENTED V 2'975 3. 752.893

4 3/? 797/7102: [amen SUBMERGED DIRECT CONTACT VAPORIZATION PROCESS This invention relates to apparatus and methods for gasifying or vaporizing liquids. More particularly, this invention is concerned with apparatus and processes for gasifying or vaporizing liquefied gases.

Although many products are stored and transported as liquids, it is often necessary for the liquids to be gasified or vaporized for various uses. This is particularly so for materials which are normally gases at ambient temperatures and pressures but which have been converted to liquids for storage and other handling purposes. Among the liquefied gases which are normally vaporized for subsequent use are liquefied natural gas, liquefied petroleum gas, methane, ethane, propane and nitrogen.

The vaporization of liquefied gases is normally effected by indirect heat exchange, such as by the use of conventional shelland-tube heat exchangers. This approach generally requires a large capital investment for equipment where the volume of gas or vapor to be produced is large. There is accordingly a need for improved apparatus and methods for gasifying liquefied gases and particularly liquefied gases which are combustible.

According to the present invention, there is provided a method of gasifying or vaporizing a liquefied gas which comprises feeding the hot products of combustion of a combustible material into and below thesurface of a mass of a liquefied gas product in a vessel, said liquefied gas being at a temperature at which at least water in the hot products of combustion is solidified, removing from the vessel unsolidified products of combustion in admixture with the vaporized gas product formed by direct heat exchange between the hot products of combustion and the liquefied gas product, and at least periodically removing from the vessel water and other materials, both solidified and unsolidified.

Also provided by the invention is suitable apparatus which can be used in practicing the described process as well as modifications thereof.

The invention will now be described further in con junction with the attachedgdrawing in which there is shown in schematic form apparatus for use in practicing the invention.

With reference to the drawing, vessel has a top semispherical shell portion 11 which is joined to a central cylindrical shell portion 12 which is broken away since it can be higher than conveniently illustrated. A bottom conical shell portion 13 is joined to shell portion 12 and completes the vessel structure. The top shell portion 11 of vessel 10 has a vertical cylindrical tubular shell portion 14 which is in communication with the inside of vessel 10. Extending outwardly from the upper part of tubular portion 14 is pipe or conduit 15. The top of tubular shell portion 14 is capped by cover 16.

The major elements of burner are located inside of tubular shell portion 14 and vessel 10. Burner 20 has a fuel supply pipe 21 in communication with the upper reduced enclosed end portion 22 of the burner. Wires 23 are located in the portion 22 to supply electric power to a spark device 24 for the purpose of igniting a combustible mixture supplied thereto by pipe 21. Combustion chamber 25 is defined by elongated tube or pipe 26 which has its lower end or mouth 27 located to be below the designated liquid level of liquefied gas to be held by vessel 10 for vaporization. Insulation 33 is advisably placed around the outside surface of the portion of tube 26 which extends into the liquefied gas. The insulation serves to keep the combustion products hotter as they leave mouth 27 of the tube and to thereby supply more heat to the liquefied gas. Tube 26 has a tapered upper section 32 which communicates with end portion 22 of the burner. A vertically positioned cylindrical baffle 28 is located in vessel 10 in spaced away arrangement from pipe 26. The bottom and top of cylindrical baffle 28 are open so that liquefied gas in vessel 10 can flow in and out thereof.

Conduit 29 communicates with the interior of vessel 10 to supply a liquefied gas to be vaporized into the vessel. insulation 30 is advisably positioned around vessel 10 although for some purposes such insulation may be unnecessary.

In practicing the process of this invention, a liquefied gas is supplied by conduit 29 to vessel 10. Sufficient liquefied gas is filled into vessel 10 to advisably bring it to a liquid levelabove the lower end 27 of the combustion tube 26 so that the hot combustion products bubble through the liquefied gas before they reach the liquid surface. A combustible mixture is supplied by conduit 21 through the reduced tubular part 22 of the burner into the combustion chamber 25 of tube 26. An ignition spark is provided by igniter 24 to cause the combustible mixture to burn. The hot products of combustion of the combustible material: stream downwardly through combustion chamber 25 and are expelled at the lower end or mouth 27 thereof. The hot combustion products thereafter flow upwardly in the liquefied gas between the outer surface of the lower end 27 of tube 26 and the inner surface of cylindrical baffle 28. As the hot products of combustion flow through the liquefied gas, heat transfer results and this leads to vaporization ofsome of the liquefied gas. The resulting admixture of vapors, formed by vaporization of the liquefied gas, and the products of combustion which do not solidify in the liquefied gas, flows upwardly in the space 31 surrounding burner tube 26 in the cylindrical portion 14. This results in heat exchange between hot products of combustion inside of tube 26 and the gas vapor and products of combustion on the outside thereof. The resulting admixture is then conveyed to pipe 15 which can feed it to any suitable destination such as a consumer line or other conduit for use in a manufacturing process.

By burning a combustible material in combustion chamber 25, some products are formed which are undesirable in the subsequently formed admixture of vaporized liquefied gas and products of combustion. Chief amongst these undesirable materials is an excess of water vapor. The amount of water and other materials however is readily reduced, and sometimes substantially eliminated, by the process of this invention by solidification through contact with the liquefied gas in vessel 10. The liquefied gas is generally at a temperature substantially below the freezing point of water so that as a result water vapor is quite readily solidified through contact and heat transfer with the liquefied gas.

It is desirable sometimes simply to reduce the amount of water vapor and other solidified products in the resulting admixture rather than to substantially eliminate these materials. By regulating the depth at which the mouth 27 of tube 26 is placed in the liquefied gas and by proper spacing of cylindrical baffle 28, the residence time of products of combustion can be adjusted to control the amounts of water vapor or other products in the admixture of combustion gases and vaporized liquefied gas.

While the use of baffle 28 is advisable it is not considered essential to practice the invention.

Any suitable combustible mixture can be supplied by means of conduit 21. The fuel can be a hydrocarbon liquid such as fuel oil, kerosene or gasoline, or a gas such as natural gas, ethane, petroleum gas or propane. In addition, the oxidizing agent can be air, enriched air or essentially pure oxygen. it is generally preferred to use as the combustible mixture a previously prepared mixture of natural gas and air. Such a mixture is especially useful if the liquefied gas to be vaporized is liquefied natural gas.

Products which solidify in the liquefied gas in vessel settle to the bottom of the vessel. The ice particles and other particles accumulate in the lower central part of the conical bottom shell portion 13 of vessel 10. These solidified materials can be removed periodically or continuously from vessel 10 by opening valve 35 and permitting the solids, together with some of the liquefied gas, to flow out by means of conduit 36. The drained material can be disposed of in any manner considered suitable. Advisably, the material is sent to a second vessel 40.

Vessel 40 is advisably noninsulated and this permits a ready heat exchange with the atmosphere and leads to melting of the ice in vessel 40 and the vaporization therein of solidified carbon dioxide and whatever liquefied gas is also fed thereto in conjunction with the solid materials. Vessel 40 can also be heated by means of a secondary source of heat, if desired, to accelerate melting of solids therein. The water can be removed by conduit 41 which communicates with the lower internal part of vessel 40. To drain the water, valve 42 is opened and the water is conveyed from the valve by conduit 43 to a suitable disposal means. Vapor which forms in vessel 40 may be removed therefrom by conduit 44, which communicates with the internal upper space of tank 40,

through valve 45, when open, and fed into conduit 46 for admixture with vapors from conduit 15. This may be desirable to control the heat value of a combustible gas which has been formed by vaporization of the gas in liquid form. Quite often a liquefied combustible gas after vaporization will have a considerably higher heat value than is either desired or required for an intended purpose and it accordingly is necessary to reduce its heating value through dilution of the vapor with a gas which supplies no heating value. Alternatively, vapor can be fed by conduit 44 to conduit 47, through valve 48 and out conduit 49 to be used as considered advisable or wasted. Of course, when this is done valve 45 is closed.

A portion or all of the vaporized gas and combustion gases can alternatively be removed from vessel 10 by means of conduit 50 instead of circulating all or part of the vapors around the burner and removing them by conduit 15.

To remove the undesirable materials from the combustion products by solidifying them in the liquefied gas, the liquefied gas in vessel 10 should advisably be below 32F. In the case ofliquefied natural gas, the liquefied gas can be obtained from a storage tank in which it is quite commonly stored at about 260F. and 15 psia for use in the described process. Also, liquefied petroleum gases, which are often stored at around 55F., are clearly cold enough for use in the described process.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is: l. The method of vaporizing a liquefied gas which comprises:

feeding the hot products of combustion of a combustible material into and below the surface of a mass of a liquefied gas in a vessel, said liquefied gas being at a temperature at which at least water in the hot products of combustion is solidified;

removing from the vessel unsolidified products of combustion in admixture with vaporized gas product formed by heat exchange between the hot products of combustion and the liquefied gas; and

at least periodically removing from the vessel solidified water.

2. The method of claim 1 in which the combustible material is a gas and it is burned with air.

3. The method of claim 1 in which the combustible material is natural gas and it is burned with air, and the liquefied gas is natural gas.

4. The method of claim 1 in which the combustible material is petroleum gas and it is burned with air, and the liquefied gas is petroleum gas.

5. The method of claim 1 in which the hot products of combustion are fed to the liquefied gas by a tube having its mouth below the liquid level in the vessel, and the vaporized gas product in admixture with the unsolidified combustion products is thereafter conducted around the outside of the tube to be further warmed and then is conveyed from the vessel.

6. The method of claim l in which at least some solidified products removed from the vessel are vaporized and then admixed with the admixture of vaporized gas product and combustion products.

7. The method of claim 1 in which solidified water is removed from the vessel and sent to a second vessel and warmed there to melt the ice, the water is drained from the second tank and vapor is removed from the second tank and fed to the admixture of vaporized gas product and combustion products.

Claims

2. The method of claim 1 in which the combustible material is a gas and it is burned with air.
3. The method of claim 1 in which the combustible material is natural gas and it is burned with air, and the liquefied gas is natural gas.
4. The method of claim 1 in which the combustible material is petroleum gas and it is burned with air, and the liquefied gas is petroleum gas.
5. The method of claim 1 in which the hot products of combustion are fed to the liquefied gas by a tube having its mouth below the liquid level in the vessel, and the vaporized gas product in admixture with the unsolidified combustion products is thereafter conducted around the outside of the tube to be further warmed and then is conveyed from the vessel.
6. The method of claim 1 in which at least some solidified products removed from the vessel are vaporized and then admixed with the admixture of vaporized gas product and combustion products.
7. The method of claim 1 in which solidified water is removed from the vessel and sent to a second vessel and warmed there to melt the ice, the water is drained from the second tank and vapor is removed from the second tank and fed to the admixture of vaporized gas product and combustion products.