US2043095A - Method of and apparatus for heating fluids - Google Patents

Description

2-,. 3 'L. DE FLQREZ 2043',095

METHOD OF APPARATUS FOR HEATING FLUIDS Filed Aug. 10, 1932 2 Sheets-Sheet 2 ATTORNEY Patented June 2, 1936 v UNITED STATES METHOD OF AND APPARATUS FOR HEATINGFLUIDS Luis de Florez. Pomfret,"" Conn., assignor to The Texas Company, New ifork, N. Y., a corporation of Delaware Application August 10, 1932, Serial No. 628,156

5 Claims. (01. 196-116) This invention relates in general to heating apparatus and more particularly to an apparatus for providing a soaking section and a method of applying soaking heat to a fluid being heated.

In the conversion of fluids, and particularly hydrocarbon oils, it is necessary to heat the fluid to a high temperature in order to obtain the desired product, and in the case of hydrocarbon oils, to obtain hydrocarbons of a lower boiling range. It has been found that the amount of heat required in the conversion of hydrocarbon oils depends upon the particular character of the oil being treated. In some instances it is desirable to reach the conversion temperature at the outlet of the heating furnace, while in other instances it is desirable to maintain the fluid at its conversion temperature for a period of time. In the latter, the effect of the soaking may be varied to meet particular conditions.

In accordance with my .invention, there is provided a furnace in which a fluid may be heated in such a manner as to raise it to the conversion temperature at the outlet thereof or maintain it at a. conversion temperature for a period of time. My invention is accomplished by a particular arrangement of heating tubes and/or a novel method of heating the tubes by a special arrangement of burners and operation of same.

An object of my inventionis to provide a furnace in which the tubes of one row are shielded by the tubes of another row.

An equally important object of my invention is to provide a method of varying the combustion in a furnace so that the temperature of the fluid may be raised to or maintained-at a desired point. I have shown this method with a plurality of individual burners although it may be done also with a single jet provided with means to guide the stream of combustion gases.

With these and other objects in view, which may be incident to my improvements, the invention consists in the several method steps and the parts and combinations to be hereinafter set forth and claimed, with the understanding that the procedure of the several necessary elements may be varied without departing from the spirit and scope of the appended claims.

In a vertical tube furnace constructed in accordance with my invention, the tubes may be placed in a vertical position and arranged to conform to the interior shape of the furnace. My invention provides an overlapping tube section which may be used as asoaking section. The overlapping tube section may be adjacent a portion of the side wall of the furnace chamber and each tube thereof may be shielded from direct radiant heat by positioning a tube of the inner row directly in front of it. In this manner the radiant heat produced by the hot products of combustion extending through the furnace does not affect the tubes of the soaking section to the same extent as the other tubes.

The method of providing a soaking zone for the. fluid being heated comprises, in accordance with my invention, a novel control of the firing of the burners. A plurality of burners are spaced so that each will affect the heating of a portion of the heating coil. The burner 01 bumers closest to the tubes in which the fluid is originally introduced may be adjusted so that its heating will be greater than the heat produced by the succeeding burners. This progressive heating of the fluid passing through the heating coil provides a novel method of operating the furnace burners so that as the fluid approaches the end of its travel through the heating coil, the burner adapted to heat this section may be fired less intensively or its heat affecting this section is less intense thereby providing the desired soaking zone. By the special burner arrangement and operation, the effectiveness of the soaking may be changed at will resulting in greatly desired flexibility.

In order to make my invention more clearly understood, I have shown in the accompanying drawings, means for carrying the same into prac tical effect without limiting the improvements in their useful applications to the particular constructions which, for the. purpose of explanation, have been made the subject of illustration.

Figure 1 is an .elevational view, partly in section, of a furnace constructed in accordance with my invention.

Figure 2 is a sectional view taken along lines- 2-2 of Figure 1.

Figure 3 is a'plan view of a burner arrangement for carrying out the method of operation using a single row of tubes...

Referring to the drawings and particularly to Figure 1, there is shown a furnace constructed in accordance with my invention. The furnace comprises a heating chamber l, a plurality of burners 2 for heating the chamber and a stack 3 for conveying the combustion gases from the heating chamber to the atmosphere. The heating chamber I is defined by refractory top, side and bottom walls. The side wall 4 and the bottom wall I are provided with a lining 5 of suitable heat insulating material and the top wall I may be made from suitable heat resisting metal. It is to be understood, of course, that the top wall of the heating chamber may be lined with a suitable heat resisting material or the bottom wall made from heat resisting metal.

The burners 2 are supported by a standard 3, which may be a suitable metal framework, resting on a base I. The burners 2 are evenly spaced below the bottom wall 1 and are adapted to direct the flames and hot products of combustion produced by each upwardly. Each burner is adapted to heat a portion of the heating chamber i, as will be more fully explained hereinafter. By locating the burners below the bottom wall and arranging them substantially at themiddle thereof, the hot products of combustion pass upwardly in an unobstructed vertical path to heat the tubes in the heating chamber l by radiant heat.

The burners are also fired in such a manner as "to prevent the flame and hot products of combustion from impinging upon the tubes.

The flame'and products of combustion after evenly distributing heat to the heating chamber are conducted to the atmosphere. A flue it of heat insulating material conducts the flue gases to the stack 3. In order to utilize any remaining heat in the combustion gases, an air preheater may be positioned in the stack 3 to heat the air for combustion purposes. The heated air would be directed by suitable conduits to the burner 2. As a further expedient for utilizing the heat remaining in the flue gases passing through the flue iii, an .economizer section may be positioned above the flue to preheat the fluid passing to the heat absorbing tubes in the heating chamber. The economizer section, if one is used, may be employed to'shield the air preheater from radiant heat thereby utilizing the majority of the available heat in the flue gases to preheat the fluid being treated.

The fluid to be heated is introduced into one of a plurality of heating tubes ll forming aheating coil. The heat absorbing tubes II are arranged vertically and the corresponding ends of each tube connected by a suitable return bend l2. The return bends l2 are located in heat insulating chambers it which may be positioned exterior of the heating chamber I, as shown. The chambers ii are provided with removable covers I 4 to permit easy access to the tubes for cleaning purposes. The bottom ends of the tubes may be connected by the return bends I 2, pcsitioned in the heat insulating chambers It in the same manner as the top ends. The tubes ll may be supported from the bottom wall 1 by any suitable supporting means and the upper ends of the tubes pass through apertures, not shown, in the top wall 8. By supporting the tubes at the lower ends, the heavy structure otherwise necessary at the top of the furnace is eliminated and the tubes, due to the free passage through the top wall 6, may expand and contract freely when subjected to changes in temperature.

The furnace may be supported by a suitable metal framework is which rests on a base ll.

My invention provides a novel arrangement of the heat absorbing tubes whereby a separate soaking section is accomplished. As is shown in Figure 2, a complete row of tubes, which will be referred to as the inner row, extends around the interior of the heating chamber l'and conforms substantially to the interior shape thereof. This row of tubes is subjected to direct radiant heat and each imparts heat to the fluid passing therethrough. The fluid enters this row of tubes, as shown, and is progressively heated until the desired temperature is attained. This temperature is attained, say, at approxi- 5 mately the point marked "A". In order to obtain the desired amount of conversion of the fluid being heated, such as ahydrocarbon oil, the

'fluid is retained in the heating chamber for an additional period of time and maintained at its conversion temperature. When the fluid is at its conversion temperature it does not require the amount of heat to maintain it at this temperature as is required in raising the temperature of the fluid. Consequently the tubes acting as a soaking section should not receive this excessive heat.

In the conversion of hydrocarbon oils, for instance, once the oil is at a conversion temperature, it does not absorb any additional heat excent for a relatively small amount necessary to approximately counter balance that given 01! by the heat of cracking.

In practicing my invention, the tubes comprising the soaking section, that is, for example, from the point "A" to the outlet tube, as indicated, are placed behind corresponding tubes of the inner row. As will be noted, each tube of the soaking section is shielded from the intense direct radiant heat by a tube of the inner row. This shielding not only prevents too much heat being imparted to the tubes comprising the soaking section but also permits the greatest heat transfer to the fluid as it enters the heating tubes. While I have shown the soaking section as extending only partly around the furnace chamber, it is to be understood that this is for illustrative purposes only. The soaking section may extend a greater distance and if desired completely around the furnace chamber. If more tubes are employed as a soaking section, each of these tubes is shielded from radiant heat by the tube of the inner row directly in front of it.

In Figure 3 I have shown an arrangement of burners which may be operated so that a soaking section is obtained in a furnace having a' single complete row of tubes conforming to the interior shape of the heating chamber. As illustrated, three burners are evenly spaced around the bottom of the heating chamber. Burner i5 is adapted to heat the oil entering the tubes and is adjusted so that the hot products of combustion and flame produced thereby will heat a certain number of the tubes. Burner I6 is similarly adjusted to heat a like number of the tubes and to raise the fluid to the desired temperature as it passes through the last tubes affected by its produced heat. Burner I! is adjusted to supply heat to a like number of tubes and this burner is operated in a manner not to increase the temperature of the fluid but to maintain it at approximately its conversion temperature.

In carrying out the method of operation, a fluid, such as hydrocarbon oil, is introduced into the first heat absorbing tube as indicated. The burner I5 is adjusted so that the heat produced thereby will influence the tubes in the section 3-0, which may for instance consist of about one third (5 3) of the total number. This burner is heavily flred in order to give of! the amount of heat required to raise the temperature of the fluid being introduced. The fluid in passing through the last tube of the section directly affected by this burner enters another section of tubes c- -p heated by the burner ls.

This

, ing section of the tubes D-E affectedby the burner II. This burner can be fired less intensively than either of the two preceding burners as it is only necessary to impart the necessary heat to the fluid to substantially counter balance the heat liberated from the fluid during conversion.

' While my method of operation has been specifically described in connection with the arrangement shown in Figure 3, it may likewise be carried out with the structure shown in Figure 1. If an overlapping section as shown in this figure and Figure 2 is employed, the plurality of burners may be operated in a manner similar to that already described and which falls within the scope of this invention. By referring to Figure 2, the method of operation will be apparent. The fluid entering the heatingcoil is raised in temperature by the heat produced by burner 2. This burner is adapted to be more heavily fired than the other burners to raise the temperature of the fluid. The fluid after being heated in the section of the heatingcoil directly affected by burner 2 passes to the section heated by burner 2". This burner is fired less intensivelythan burner 2' but sufficiently great to impart additional heat to the fluid passing through the heating coil. After passing through the section of the heating coil directly affected by the burner 2", the fluid is next passed to the section heated by burner 2. This burner is fired less intensively than burner 2" as the fluid is near its conversion temperature and it is only necessary to impart a small amount of additional heat thereto to raise it to its conversion temperature. i

The fluid, at its conversion temperature, is passed to the overlapping or soaking section. As before explained, it is only necessary to impart the necessary heat to the fluid to substantially counter balance that liberated as the heat of conversion. The overlapping or soaking section is, as before explained, shielded from direct radiant heat by'the tubes of the inner row. The heat imparted to the fluid in the soaking section is sumcient to substantially counter balance that liberated as heat of conversion and consequently the fiuid is maintained at substantially its conversion temperature for an additional period of time.

If the particular fluid being treated does not require soaking, my furnace may be operated so that the conversion'temperature is reached at approximately the outlet.. The burner adapted to heat the section of tubes acting as a shield for the tubes of the overlapping section is more heavily fired and the succeeding burners fired in such a manner as to raise the temperature of the fluid to approximately its conversion temperature before entering the overlapping section. Due to the heavy firing of the burner adapted to heat the fluid passing through the shielding tubes, additional heat is imparted to the overlapping tube section, thereby increasing the temperature of the fluid passing therethrough to its conversion point. It is to be understood that the arrangement in Figure 3 may also be operated'in such a manner as to raise the temperature of the fluid to conversion at approximately the outlet of the heating coil.

- From the foregoing the manner in which the burners are operated in accordance with my invention will be clearly understood. My method of operation broadly comprehends regulating the, extent of firing of a plurality of burners so that the fluid in its passage through the heating absorbing tubes is progressively raised to or maintained at its conversion temperature for a period of time. While I have shown and described three burners for carrying out the method in accordl0 ance with my invention, it is to be clearly understood that this is for illustrative purposes only and any number of burners may be employed. The burners are grouped so that the .heat produced by each will affect a certain number of 15 tubes in order to progressively raise the fluid to or maintain it at the desired temperature.

It is to be understood that the invention is not limited to any particular type of burner or fuel, as either gas, liquid or solid fuel may be used with a 0 burner best adapted for the type of fuel chosen. Moreover my invention is not limited to a cylindrical shaped furnace as this is for illustrative purposes only.

It has been found that by firing the burners in the manner described, less heat is required to raise and maintain the temperature of the fluid being treated. In the cracking of a hydrocarbon oil, with the burners operated in the manner described, the overall furnace temperature has been 39 found to be less than that required when all burners are fired evenly. In a particular operation it was ascertained that the furnace temperature was decreased from 1020" to 990 F. and the same amount of cracking obtained. 35

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the precise details of construction herein set forth, by

way of illustration, as it is apparent that many 40 changes and variations may be made therein, by those skilled in the art, without departing from the spirit of the invention, or exceeding the scope of the appended claims. I claim: 45

1. In a furnace for heating hydrocarbon fluids, a heating chamber, a plurality of interconnected heat absorbing tubes within said chamber forming a main heating coil, a plurality of means for producing hot products of combustion for 50 heating said coil preponderantly by radiant heat associated with said heating chamber, each of said means being adapted to produce hot products of combustion having a temperature different from that of the others, and positioned, 55 with respect to a portion of said heat absorbing tubes, so that the direct intense radiant heat therefrom affects primarily the aforementioned portion of heat absorbing tubes, other interc'onnected heat absorbing tubes which comprise a 0 soaking section for said hydrocarbon fluid adapted to be heated preponderantly by radiant heat, the tubes of the soaking section being shielded from intense direct radiant heat from the hot products of combustion by. tubes of the main 65 heating coil positioned between said soaking tubes and the hot products of combustion and directly in front of said soaking tubes.

2. In a furnace for heating hydrocarbon fluids, a vertical heating chamber, means for producing hot products of combustion for said heating chamber, a plurality of vertical interconnected heat absorbing tubes within said chamber forming a main-heating coil extending substantially entirely around the heating chamber and adapted to be heated preponderantly by radiant heat from said hot products of combustion, other vertical interconnected heat absorbing tubes immediately adjacent the tubes of the main heating coil which comprise a soaking section for saidhydrocarbon fluid adapted to be heated preponderantly by radiant'heat, the vertical tubes of the soaking section extending only part way around said combustion chamber with the several tubes being shielded from intense direct radiant heat from said hot products of combustion by respective vertical tubes of the main heating coil positioned between said soaking tubes and the hot products of combustion and directly in front of said soaking tubes.

3. A method of heating hydrocarbon fluids which comprises passing a continuous stream of hydrocarbon fluid in a succession of vertical paths in a primary bank of interconnected heat absorbing tubes disposed in .a vertical heating chamber, supplying hot products oi combustion to the heating chamber to heat said bank of tubes preponderantly by radiant heat and passing the hydrocarbon fluid thus heated through a secondary bank of interconnected heat absorbing tubes extending only part way around said heating chamber and shielded from intense direct radiant heat from said hot products of combustion by tubes of the primary bank positioned between the secondary bank of tubes and the hot products of combustion and directly in front of the secondary bank.

4. A method of heating hydrocarbon fluids which comprises passing a continuous stream of hydrocarbon fluid through a primary bank of interconnected heat absorbing tubes disposed in a heating chamber, supplying hot products of combustion o! diii'erent degrees of temperature from a plurality of separate means in said heating chamber to thereby apply direct intense radiant heat to said bank of tubes of diflerent degrees of temperature with respect to different portions of said bank, passing the hydrocarbon fluid thus heated through a secondary bank of interconnected tubes heated preponderantly by radiant heat from said hot products of combustion but shielded from intense direct radiant heat from the hot products of combustion by tubes of the primary bank of tubes positioned between said secondary bank and the hot products of combustion and directly in front of the secondary bank. 5. A method of heating hydrocarbon fluids which comprises passing a stream of hydrocarbon fluid in vertical paths through a vertical heating coil in a single unobstructed heating zone, producing a plurality of columns of hot products of combustion for passage through said heating zone in an unobstructed path and substantially out of contact with said vertical heating coil, subjecting separate portions oi said heating coil to mainly the radiant heat of a separate column of said hot products of combustion produced for each portion and regulating the temperature of each column of hot products of combustion to thereby vary the intensity of radiant heat absorbed mainly by each portion of the heating coil from its respective column of hot products of combustion, whereby the hydrocarbon fluid passing through the heating coil is progressively increased in temperature.

LUIS nn FLOREZ.

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