US1841072A - Oil cracking still - Google Patents

Description

Jan. 12, 1932. H w|DDELL 1,841,072

011. cimcxme STILL Filed Aug. 14, 1926 Patented Jan. 12, 1932 HENRY E. WIDDELL, OF KANSAS CITY, MISSOURI OIL CRACKING STILL Application filed August 14, 1926. Serial No. 129,170.

This invention relates to heating apparatus and method, and more particularly to heaters for fluid such as are used in oil cracking stills.

An object of this invention is to increase the thermal efliciency of heater for fluids.

Another object is to provide means for controlling the temperature of gases in a heater without wasting the heat developed.

Another object is to protect the walls of the heating apparatus from excessive heat.

Another object is to provide means for utilizing the radiant heat generated upon combustion of fuel.

Another object is to provide an improved method of controlling the temperature of combustion gases and conserving the heat developed.

Other objects will hereinafter appear.

In the present common practice, oils are cracked by being heated in oil-fired stills. If the oil fuel is eificiently burned with a proper excess of air (about 50%) the temperature of the gases will be about 3500 F. In certain instances it is desirable that the gases of combustion which contact with the container holding the oil to be cracked shall. be approximately from 1300 F'. to 1600 F. In Jrder to reduce the gases to the desired temperature, large quantities of air in excess of zhat required for combustion (generally from 200 to 250%) are admitted and absorb much )f the heat developed by the fuel. The vol- .inie of stack gases is, of course, large and .he heat content represents approximately of he fuel burned.

I prop se to provide means for absorbing ieat from the burning gases in such man- 181 that it may perform some useful purpose ind at the same time reduce the temperature )f the gases to a desired point without the LdII'llSSlOIl of more air than is necessary to nsure complete combustion. The gases proluce during combustion, a temperature of .bout 3500 F. and can be cooled to between 400 F. and 1600 F. while containing only bout %excess of air. The volume of tack gases is small and their heat content epregents only about 13% of the fuel conume A convenient manner of absorbing the heat is to expose to it some fluid, which may be a liquid, vapor, gas or mixture of any or all of these, other than the oil being cracked. The fluid should not only be capable of absorbing heat, but should be such that it being heated will produce some useful result. Examples of such fluids are oils or water which it is desired to heat or vaporize, or steam to be superheated.

The invention will be better understood from the description of one practical apparatus, in which it is embodied and by which it may be practiced, illustrated in the accompanying drawings, in which Fig. l is a longitudinal section of the apparatus;

Fig. 2 is a transverse section taken on line 11I1 of Fig. 1; and

Fig. 3 is a plan section taken on line IIIIH of Fig. 1.

The furnace comprises a top 1, sides 2 and 3, and ends 4 and 5 of a suitable refractory material, such as fire brick. The interior space is divided into two compartments 6 and 7 by a bridge wall 8 which extend well up toward the top. Compartment 6 is preferably considerably larger than compartment 7.

In compartment 6, hereinafter referred to as the combustion chamber, are burners 9 b which a fuel, such as oil, may be introduced.

Compartment 7, hereinafter called the cracking chamber, communicates with a flue 10 through which the burned gases may escape after passing through both chambers.

Within the combustion chamber are a series of tubes 11 supported by and close to the walls of the chamber. These tubes are so connected a fluid may circulate'therethrough in a continuous circuitous and upward path from the inlet pipe and valve 12 to the transfer pipe 13.

The transfer pipe communicates with a series of tubes 14 supported by and close beneath the top of the furnace and co-extensive therewith. Fluid may travel continuously upward and back through these tubes until it reaches discharge pipe and valve 15.

The above described tubes are for the circulation of the cooling fluid, not of the oil to be cracked.

In'the cracking chamber is a bank of tubes 16, having an inlet pipe and valve 17 through which oil to be cracked may be introduced and an outlet and valve 18 through which this oil is discharged.

By arranging the cooling-fluid tubes as shown, the tubes are supported on the walls and top. They are positioned toshield and draw heat from these surfaces and thus reduce their temperature, thus reducing the heat which would otherwise radiate from the furnace and at the same time lengthen the life of the walls. They absorb the radiant heat generated by the burning fuel. They are out of the path of the hot gases and do not absorb heat from these by convection but permit this to be delivered to the cracking tubes.

The cooling-fluid is one which it is desired to heat so that the heat absorbed is not wasted while the temperature at the cracking chamber is kept down to any desired point.

While I have described the illustrated embodiment of my invention with some particularity, obviously many others will readily occur to those skilled in this art and I do not therefore limit myself to the precise details shown, but claim as my invention all embodiments coming Within the scope of the appended claim.

What I claim is:

The method of controlling the temperature in an oil cracking furnace which comprises burning fuel in the furnace with small excess of air and passing a heat-absorbing fluid through passages adjacent the walls thereof at a rate to absorb sufiicient heat to reduce the gases to the desired temperature, and exposing the oil to be cracked only to the cooled gases.

In testimony whereof I hereunto aflix my signature this 9th day of August, 1926 HENRY E. WIDDELL.

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