United States Patent 3833014

A storage tank incorporating heating means for a liquid asphalt incorporates means for introducing and retaining low pressure inert gas as a sealing medium to provide emission free heated asphalt storage.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
137/334, 137/559, 222/23, 222/146.2
International Classes:
B65D90/44; (IPC1-7): F16K9/00
Field of Search:
222/146,23,25,53 137
View Patent Images:
US Patent References:
3348739Hot mix storage bin1967-10-24Brock
2917071Pressure relief valve1959-12-15Crumley et al.
2267594Pressure adjuster for gaseous discharge lamps1941-12-23Lowry et al.
1874727Liquid sealed vacuum and pressure relief valve1932-08-30Wiggins et al.
1662263Antifreezing connection for tanks and regulators1928-03-13Harris
1651051Liquid-sealed vacuum and pressure-relief valve1927-11-29Wiggins

Primary Examiner:
Reeves, Robert B.
Assistant Examiner:
Skaggs, Grant H.
Attorney, Agent or Firm:
Harpman, Webster B.
I claim

1. A storage tank for storing hot liquid asphalt, inlet means and outlet means connected with the tank for placing asphalt in the tank and removing it therefrom, heater means in the tank for heating hot liquid asphalt in the tank, gas inlet means in an upper portion of the tank connected with a source of inert gas for maintaining inert gas in the tank over the liquid asphalt at an elevated pressure to prevent oxidation and vaporization of the asphalt, a gas sealing and venting means connected with the upper portion of the tank to maintain the inert gas in the tank at a low positive pressure and to relieve excess pressure and vacuum in the tank, said gas sealing and venting means including a pair of upright, opaque tubular members in fluid communication with one another through a horizontal portion at their lower ends, one of said members in fluid communication at its upper end with the interior of the tank and the other member open at its upper end to atmosphere, a liquid in said tubular members effecting a fluid seal between the interior of the tank and the atmosphere, and a separate, tubular sight glass connected at the upper and lower ends thereof with each tubular member adjacent the upper and lower ends of the tubular members and extending in spaced, substantially parallel relationship to the tubular members to give a comparative visual indication of the fluid levels in the tubular members and thus enable rapid visual determination of the status of the pressure control effected by the seal.

2. A storage tank as in claim 1, wherein a gas pressure regulator is connected between said source of gas and said gas inlet to control the pressure of gas in the tank.

3. A storage tank as in claim 1, wherein said tubular sight glasses are disposed side by side for easy visual comparison of the liquid levels in the upright tubular members, said sight glasses connected at their lower ends to the lower ends of the tubular members at a point below the interconnection between the lower ends of the tubular members.

4. A storage tank as in claim 3, wherein skid means are on said tank for moving said tank across a supporting surface, and said source of inert gas comprises a pressurized container of inert gas carried by the tank.


1. Field of the Invention

This invention relates to the storage of heated liquid asphalt and more particularly tanks incorporating heating means and means for introducing inert gas and maintaining the same to prevent vaporization of the volatile constituents of the heated asphalt.

2. Description of the Prior Art

No prior art is known wherein liquid asphalt may be simultaneously stored and maintained in an emission free state by the presence of a low pressure inert gas barrier layer provided in the storage tank. Inert gas seals have been used with respect to asphalt containing paving mixes including various sized aggegates and "fines" and the like such as disclosed in U.S. Pat. Nos. 3,348,739 and 3,532,252. These prior art devices rely on mechanical seals for maintaining the inert gas and are not used in connection with the heated storage of liquid asphalt as in the case of the present invention.


A storage tank incorporating integral heating means for storing and maintaining liquid asphalt in a heated condition wherein the volatile constituents thereof tend to vaporize readily, is disclosed as provided with a seal and a charge of inert gas maintained by the seal at low pressure to effectively control vaporization of the asphalt components and prevent their emission from the heated storage tank.


FIG. 1 is a perspective view of the heated storage tank for liquid asphalt with parts broken away and parts in cross section.

FIG. 2 is an enlarged detail taken on line 2--2 of FIG. 1 and illustrating the inert gas sealing means thereof.


In the form of the invention chosen for illustration, the asphalt storage tank with inert gas seal consists of a cylindrical tank 10 having closed ends 11, one of which is shown in FIG. 1 of the drawings, the tank 10 incorporating an internally extending heater tube 12 positioned inwardly of one end thereof and communicating with a suitable burner for introducing the products of combustion thereinto, not shown. The heater tube 12 is preferably of a construction which permits so-called direct firing of the same without the attendant build-up of coking temperatures on the surfaces thereof which would be objectionable and such devices are known in the art.

As illustrated in FIG. 1 of the drawings, liquid asphalt is present in the tank to the level A as illustrated and the area thereabove is filled with an inert gas such as nitrogen N under low pressure such as, for example, 2 ounces. The tank 10 is sealed by suitable valves on the inlet and outlet openings thereof, one of which is indicated by the numeral 13 as illustrated. Both ends of the tank are provided with access platforms and operating equipment, one of the platforms being indicated by the numeral 14. The tank 10 is preferably mounted on skids 15 rendering the same portable and in the end illustrated in FIG. 1 of the drawings, is provided with a gas sealing vent device 16 communicating with the tank 10 by way of a tubular fitting and coupling 17.

The source of inert gas, such as nitrogen, is provided by a cylinder 18 positioned adjacent one end of the tank 10 and supported on one of the skids 15 and secured by a strap 19. The nitrogen cylinder 18 is provided with a regulator 20 and a pressure gauge 21 and a gas delivery tube 22 extends from the pressure regulator 20 to an upper portion of the tank 10 where it communicates with the interior thereof.

The gas sealing vent device 16 provides the only means of venting the tank 10 when it is partially filled with liquid asphalt and the same is being heated.

By referring now to FIG. 2 of the drawings an enlarged detail with parts broken away and parts in cross section and illustrating the gas sealing vent device 16 may be seen. By referring thereto it will be seen that the tubular conduit 17 which establishes commnication with the interior of the tank 10, communicates with and supports the gas sealing device 16 and more particularly one cylindrical chamber 23 thereof with which the tubular conduit 17 directly connects. The upper end of the cylindrical chamber 23 is closed as at 24 and the lower end is closed as at 25. A sight gauge including a glass tube 26 is connected with one side thereof by appropriate fittings 27 so that the level of a suitable liquid such as hydraulic oil O therein may be readily determined. The cylindrical chamber 23 communicates with a second cylindrical chamber 28 by way of a tubular connection 29 adjacent their lowermost ends. The second cylindrical chamber 28 has a closed lowermost end 30 and it is also provided with a sight gauge 31 connected to the interior thereof by suitable fittings 32 so that the liquid level of a suitable fluid such as oil O therein may be visually determined. The uppermost end of the second cylindrical chamber 28 is provided with an apertured closure 33 with the aperture communicating with an inverted U-shaped vent pipe 34, the open end of which communicates with the atmosphere.

Those skilled in the art will observe that when liquid asphalt in a heated state in the cylindrical tank 10 is covered by a layer of inert gas such as nitrogen, under pressure such as hereinbefore described, the volatile constituents of the liquid asphalt will be confined and varporization largely controlled and emission of any such vaporization completely controlled. The inert gas present in the upper portion of the cylindrical tank 10 communicates through the tubular means 17 with the cylindrical chamber 23 and in order to reach the atmosphere must move downwardly through the hydraulic oil O which is present in the lower parts of both of the cylindrical chambers 23 and 28, and it must displace that hydraulic oil in order to pass the same. The amount of the oil will obviously provide the desired pressure control with respect to the nitrogen pressure desired in the cylindrical tank 10.

As illustrated in FIG. 2 of the drawings, the nitrogen pressure of approximately two ounces in the cylindrical tank 10 will result in the difference in the liquid levels of the hydraulic oil O in the cylindrical chambers 23 and 28 as illustrated and visual indication and determination of these levels readily indicates the satisfactory status of the nitrogen and the emission control being afforded.

It will thus be seen that an asphalt storage tank with an inert gas seal has been diclosed which is particularly suitable for storing asphalt in a heated and being heated state as it will effectively control vaporization of the volatile components thereof and stop any emission of such volatile components therefrom.

The above described structure provides a relatively inexpensive and highly dependable control means for heated asphalt and is versatile in that it may be used with various inert gases under varying pressures as may be desirable in various field applications.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.