US3212493A - Gas-fired heater with remote air inlet - Google Patents

Description

06L 1965 M. L. LACEY 3,21 93 GASFIRED HEATER WITH REMOTE AIR INLET Filed Aug. 18, 1961 AIR INTAKE TANK I INVENTOR.

M.L. LACEY mklw United States Patent 3,212,493 GAS-FIRED HEATER WITH REMOTE AIR INLET Miles L. Lacey, Okmulgee, 0kla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 18,1961, Ser. 190,132,411 1 Claim. (Cl. 126360) This invention relates to a gas-fired heater having a remote air inlet for safety reasons. In another aspect it relates to a tank heater adapted for use where explosive or inflammable atmospheres may be encountered.

It is standard practice in the petroleum industry to provide stock or storage tanks with individual heating for warming liquids, or reducing the viscosity of hydrocarbon fluids such as asphalt. These tanks are generally vented, and discharge vapors may tend to accumulate around the base of such tanks. Also, the tank heating means are preferably disposed in the lower portion thereof. This facilitates circulation of stored liquid within tank by convection currents as it is being heated. The heating means comprise, in part, some type of burner often external to the tank. The burner of course, requires free oxygen containing gas, usually air, to support combustion chamber of the fuel. If the air is drawn into the combustion chamber from the area about the base of the tank, it may well be laden with explosive vapors and flash-back can occur. This hazard must be overcome for safe operation of the heater.

It is, therefore, an object of this invention to provide a gas-fired heater for a storage tank which is operated in an explosion proof manner.

It is another object to provide flame arresting means which admits air to the burner and which is highly effective for the purpose intended.

Still another object is the provision of a gasburner in which both the pilot flame and burner flame are fully enclosed and receive their entire air supply for combustion from an explosive vapor-free atmosphere.

Various other objects, modifications and alterations of the invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention and it should be understood that the latter is not necessarily limited to the aforementioned discussion.

According to my invention, there is provided a gas-fired heating apparatus for heating a liquid contained in a tank, the apparatus comprising heater means external to said tank which is adapted to withdraw air for combustion of fuel gas from the outside atmosphere at a point remote from the explosive vapors around the base of said tank, the burner being adapted to pass the hot combustion gases produced therein to one end of a tubular heating means disposed within the lower portion of said tank, the other end of said heating means passing through the tank wall and connecting with a vent conduit communicating with the outside atmosphere.

In the drawing, storage tank 11, of about 40 feet in diameter and 30 feet in height, is provided with a tank heater, generally designated 12. Heater 12 comprises a vapor tight, flame shield 13, provided with a sealed access port 14. Shield 13 may have a cylindrical from which is horizontally disposed.

Within shield 13 is positioned a gas-fired burner 16, such as the John Zink JZH-TI-I-313, a 1,500,000 B.t.u./ hr. burner, suitable for combustion of natural gas. A gas supply conduit 17 passes from a source of fuel gas (not shown) through a packing gland (not shown) near the external end of shield 13 to burner 16. An air inlet conduit 18 forming a leak-tight joint, such as accomplished by welding, communicates with shield 13. The hot combustion gases from the burner pass from Within shield 13 via a sealed flanged connection 19. Thus, it is seen See that explosive vapors in the vicinity of the tank base, and the shield, cannot 'be drawn into the flame area. 'This will prevent .the burner from igniting the vapors and causing the resultingfire to flash 'back'to the source of the vapors.

The combustion gases pass thru flange 19 into a tubular "heating means 21, "such as a horizontally-disposed -U type heatertube. -One arm'of tube 21 passes through the wall of tank 11 and the other emerges therefrom at a separate point, both by way of leak-tight joints. U tube 21 permits the hot combustion gases to heat the stored liquid. The return leg of the U-tube connects via flange 22 with a combustion gas exhaust conduit 23. This vent conduit preferably opens to the atmosphere quite high above the ground for quick dissipation, and in this manner will not introduce any uncombusted fuel gas into the vicinity of the tank base. Obviously, the ends of the inlet and outlet conduits are spaced some feet apart, so that combustion gases will not be drawn into the air inlet.

Regarding air intake conduit 18, it is seen that the inlet end is also high above the base area, perhaps 40' above ground. With this arrangement, a flame arrestor of the screen or grid type on the air intake, common in the prior art, is dispensed with. In a preferred embodiment, the air inlet is above the top of the tank, so that vapors from the stored liquid will also not be drawn thereinto.

In operation, when heating of the stored liquid is desired, burner 16 is manually started and safe operation can be expected regarding air intake and burner ignition. Pilot light means can be used.

From the foregoing description, it is apparent that I have provided a tank heater which is free from the danger of igniting explosive ground vapors upon ignition and during operation of the external burner component of said tank heater.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention and it should be understood that the latter is not necessarily limited to the aforementioned discussion.

I claim:

Means for heating a stored fluid in a tank from which inflammable vapors may be emitted, comprising:

a tank containing said fluid;

a heater tube in said tank, said heater tube having a fluid inlet and a fluid outlet extending through the wall of said tank near the lower end thereof;

a fluid fuel burner communicating with said fluid inlet of said heater tube;

a cylindrical horizontally disposed non-porous flame shield surrounding said burner and forming a vapor tight seal with the wall of said tank around said fluid inlet;

a fuel inlet pipe to feed fuel to said burner through said flame shield and forming a vapor tight seal with said flame shield to prevent communication between the interior of said flame shield and the surrounding atmosphere;

a non-porous air inlet stack feeding air to said burner through said flame shield and forming a vapor tight seal with said flame shield, said air inlet extending from said flame shield to a first location sufliciently above said tank to prevent the inlet of vapors of the stored fluid thereinto, said air inlet stack permitting the inlet of air only at said first location above said tank; and

an exhaust stack from said heater tube extending from said fluid outlet to a second location above said tank, sufficiently removed from said first location to prevent the inlet of combustion gases into said air inlet.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Edminstrer 126-360 X Shivlar 126-360 5 Giordan 126-360 Mansfield et a1. 126-360 Ingold 126-368 Riemenschneider 126-360 Woodson 126-91 1 Elze et a1. 126343.5

4 Walker et a1. 126-360 X Machniak 126-85 Ryder 126-307 Harshfield 126-360 X Vitale 126-85 X FOREIGN PATENTS Great Britain.

JAMES w. WESTHAVER, Primary Examiner.

PERCY L. PATRICK, ROBERT A. DUA, Examiners.

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