US1821326A - Process for heating decomposable materials - Google Patents

Description

Sept. 1, 1931. J. R. scHowaEkc; 1,821,326

PROCESS FOR HEATING DECOMPOSABLE MATERIALS Filed June 11, 1927 Q //II1II/I//A7111/11/1/1/11111/0 114w. 00 a 1 s,

v 6 JACKSON Rficuovmuwa. anwntoz Patented Sept. 1, 1931 UNITED STATES PATENT OFFICE I JACKSON R. SCHONIBERG, OF WESTFIELD, NEW JERSEY, ASSIGNORJIO STANIJARD OIL DEVELOPMENT COMPANY, A. CORPORATION QE DELAWARE vPROCESS FOR HEATING DECOMPOSAIBLE MATERIALS Application filed June 11,

The present invention relates to the art of heating fluids by combustion gases and more specifically comprises an eflicient method for, the distribution of heat in furnaces to prevent local over-heating and at the same time to use fuel economically. M' method and apparatus therefor will be fu ly understood from the following descripton and the attached drawings referred to in the same.

In the heating of fluids which are sensitive to excessive temperatures, such as oils and the like, there has been great difliculty in obtaining efiicient combustion. If the excess air, as indicated by flue gas analysis, is kept low, the temperature in the zone of combustion will be high and radiation from the flames and the inner walls of the furnace is often injurious to the heating surface and the material being heated. In oil heating equipment this is especially troublesome since overheating of the oil causes a deposition of coky material on the heating surface and the still J may be seriously damaged.

The condition above described is generally met by allowing a large excess of air to enter the combustion zone with the result that the temperature therein is lowered to a point at which the radiation is not sufiiciently intense to cause over-heating, but fuel efliciency suffers in consequence as will be well understood.

It is a well known fact that certain gases, notably steam and carbon dioxide, are semiopaque to heat rays. The expression semiopaque means that a certaln proportion of heat passing by radiation into a layer of gas is absorbed by the gas itself, depending on the thickness of the layer and the nature of the gas, so that only a certain fraction of the radiation passes through and leaves the as layer. My invention consists in maintalmng a layer or bank of such a semi-opaque gas between the radiating elements and the stall surface. A part of the heat passes directly through the gas layer and is absorbed by the metal surface while the remainder is absorbed by the gas layer. As the gas becomes heated it may be drawn off and utilized in another part of the furnace.

Referring to the drawings, Fig. I is a ver- 1927. Serial No. 198,134.

tical elevation in section of a pipe still heating coil constructed accordingto my invention and,

Fig. II shows a shell type oil still, adapted for operationof my process.

the furnace by the stack 7 which is fitted with damper 8.

In sectionl the heating surface 9, in the form of parallel tubes, is placed well above the furnace floor and the height above the burner level is suflicient so that a bank or layer of a semi-opaque gas may be maintained between the burner level and the heating surface. The semi-opaque gas may be admitted by pipes 10 above burners 6. The top of the combustion chamber is sealed so that the only escape for combustion gas is through holes 4, which are close to the floor level, preferably in alignment with the burners 6, and by this means the layer of semiopaque gas may be maintained with little tendency for hot gas from the flames sweeping up around the tubes 9. Additional heating surface 11 is distributed throughout the section 2 in order that the temperature of the flue gas may be reduced to an economical degree before discharge to the stack. The semi-opaque gas is drawn from any convenient source not shown in Fig. 1 and, after discharge from the fire box. It is mixed with the combustion gases and flows through section 2. The oil is pumped first through the convection section where it is preheated and through the combustion section as indicated by the arrows, or in any other suitable manner, and is finally discharged to a vaporizing drum or tower not shown in Fig. 1.

In Fig. II my invention is applied to a crude or rerun still of the shell type. As in Fig. I, the character 1 designates the combustion chamber and numeral 2 again refers to the convection chamber. In this case, however, the combustion chamber consists of a number of flues extending from end to end of the still. The other elements are numbered as in Fig. I. The shell 9' is protected by the semi-opaque gas admitted by line 10 above burners 6. A fan or blower 13 draws flue gas, containing steam and CO from flue 12 and for use as a part of thatmaking up the layer injected at 10. The other part of the flue gas passes from flue 12 into stack 7 The other elements of the still such as charging line, vapor line and tar draw-off are indicated by 13, 14 and 15 respectively.

In the operation of my process the semi opaque gas is interposed as a thick bank or layer between the still surface and those elements from which the intensity of radiation is high. The thickness of the gas layer and the nature of the gas determine the quantity of heat absorbed in the combustion section and regulation of the heat absorption may be maintained by control of the flow of interposed gas and by its composition. It is important to keep the layer of gas intact as well as possible so that the construction of the back wall 3 should be as described. It has been found that, when burning fuel with about20% excess air and heating oil to a temperature in excess of 750 F., a layer of from 1 to 3 ft. in thickness and containing about 11% CO and 1.2% H 0 was sufficient to protect the tubes from over-heating.

While my invention has been described in reference to heating oil, it should be understood that the process is applicable to the heating of any fluid sensitive to over-heating. My invention is not to be limited-by any theory of the mechanism or by any example given in the way of illustration. I wish to be limited only by the following claims, in which I claim all novelty inherent in my invention.

It is pointed out that the term source of radiation used in the claims includes both solid radiating surfaces such as highly heated furnace walls and the layer of hot combustion gases.

I claim:

1. The method for protecting heat absorption surfaces of a still from local overheating by radiation, comprising maintaining a relatively cool layer of a semi-opaque gas between such surfaces and the source of radiation.

2. The method for protecting heat absorption surfaces of a still against local over-heating due to radiation, comprising flowin a layer of relativel cool semi-opaque gas lae tween the heat absorption surfaces and the source of radiation.

3. The method for protecting heat absorption surfaces of an oil still against local overheating due to excessive radiation comprising keeping the flames and highly heated gas out of contact with the heating surface and tempering the intensity of radiation by interposing a layer of relatively cool, semiopaque gas between the source of radiation and the heating surface.

4;. The method for economically heating fluid sensitive to excessive temperatures comprising burning fuel with relatively small excess of air in a radiation zone, interposing a layer of semi-0 aque gas between the flames and heating sur aces containing the fluid to be heated, withdrawing and mixing the gases from the radiation zone, passing the same to a second heating zone and absorbing heat from said gases therein.

5. A method according to claim 3, in which the semi-opaque gas is at least one foot in thickness and contains substantially equal parts of carbon dioxide and water va or.

JACKSON R. SCHONB RG.

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