US2046897A - Heating of fluids - Google Patents

Description

July 7, 1936. J, B, HEID 2,046,897

HEATING OF FIKUIDS Filed Sept. 22, 1934 2 Sheets-Sheet 2 I I (5f FIG. 3

INVENTOR 9i JACOB BENJAM N HEID BY d TTOR Y Patented July 7, 1936 2,048,897 HEATING or mum's Jacob Benjamin Held, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application September 22, 1934, Serial No. 745,095

4 Claims.

This invention particularly refers to an improved furnace for heating fluids which is particularly adapted for heating hydrocarbon oils 1 to the high temperatures required for their pyrol lytic conversion and is particularly advantageous as applied to the simultaneous treatment of two or more separate streams of the same or different hydrocarbon oils.

One of the principal advantages of the present 10 invention is the wide flexibility of operation which it permits. The furnace structure and methods of operation provided by the present invention are adaptable to the treatment of a single stream of fluid or to the simultaneous treatment of two 15 or more streams of the same or different fluids. As applied to the treatment of a single stream of fluid the features of the present invention permit independent control of the heating conditions at various points along the path of flow of the 20 fluid through the heating coil or fluid conduit, thus permitting accurate control of the heating curve, which control is particularly desirable in the conversion of hydrocarbon oils. As applied to the simultaneous treatment of more than one 25 stream of the same fluid, the present invention permits the treatment of larger quantities of fluid in a single furnace than is otherwise possible without excessive pressure drop through the fluid conduit, due to friction. It also provides 30 for subjecting at least two streams of the same fluid to substantially equal heating conditions and further provides for fairly accurate control over the type of heating curve obtained for the total fluid undergoing treatment, although not to so 35 great an extent as when applied to the treatment of a single stream of fluid. As applied to the simultaneous treatment of more than one stream of difierent fluids, the present invention permits accurate and independent control over the heat- 40 ing conditions to which each stream is subjected and permits fairly accurate and independent control over the type of heating curve obtained for each stream.

Another important feature of the present in- 45 vention is the provision for obtaining exceptionally high rates of heat input to certain portions of the fluid conduit and the materials passing therethrough. This is accomplished by subjecting each tube in those portions of the fluid conduit wherein high rates of heating are desired Y to heating by direct radiation from the flames and hot refractory walls of the furnace so as to obtain an average rate of heat input around the entire periphery of the tube which approaches 55 the maximum permissible rate of heating at any point thereon, thereby materially increasing the average rate of heating. This is accomplished without sacrificing furnace efflciency by means of employing other heat absorbing surfaces beyond the zones of the furnace wherein said high rates of heating are employed so as to decrease the temperature of the combustion gases leaving the furnace.

The accompanying diagrammatic drawings (Fig. 1) is a sectional elevation of one specific type of furnace structure embodying the features and advantages of the present invention, and

Figs. 2, 3 and 4 of the drawings illustrate several of the many possible specific flows which may be employed through the fluid ,conduit of the furnace structure shown in Fig. 1.

' Referring particularly to Fig. l of the drawings, the main furnace structure comprises side walls I and 2, a roof 3, a floor 4 and end walls, which are not illustrated in the particular view of the drawings here shown. The interior of the furnace is divided, by means of bridge walls 5 and 6 extending between the end walls of the furnace, into two separate combustion and heating zones 1 and 8 and a centrally located fluid heating zone 8.

A fluid conduit or tube bank ll comprising, in the case here illustrated, two vertically parallel rows of horizontally disposed tubes In is located within combustion and heating zone I midway between side wall I and bridge wall 5. Another tube bank l2 which, in the case here illustrated, is similar to tube bank II and comprises two vertically parallel rows of horizontally disposed tubes I0 is similarly located in combustion and heating zone 8 midway between side wall 2 and bridge wall 6. Another tube bank l3 comprising,

in the case here illustrated, asingle horizontal row of horizontally disposed tubes i0 is located adjacent the floor of combustion and heating zone I and a similar tube bank I4 is located adjacent the fioor of combustion and heating zone 8. Another tube bank l5, comprising, in the case here illustrated, a single horizontal row of horizontally disposed tubes I0, is located adjacent the roof of the furnace, portion iii of this bank being located above combustion and heating zone 1, portion l5" above combustion and heating zone 8 and portion I5' above the centrally located fluid heating zone 9. Another tube bank 16 comprising, in the case here illustrated, a plurality of superimposed horizontally parallel rows of horizontal tubes I0 is located within fluid heating zone 9 of the furnace.

Combustible fuel and air is independently supplied in regulated quantities to each of the separate combustion and heating zones I and 8 through burner ports H which are located on opposite sides of each of the tube banks II and H. The fuel may be of any desired form, such as oil, gas or pulverized solid fuel, and is supplied through suitable burners, the tips of which are indicated at l8. Air for atomization may also be supplied through the burners and additional air for combustion as well as any desired quantity of excess air may be supplied through each of the burner ports ll. The total quantity of fuel supplied to each combustion zone as well as the relative proportion of fuel and air is independently controlled and preferably independent control is also exerted over the quantity of fuel and the proportion of fuel and air suppliedthrough each burner port, so that substantially the same or-different firing conditions may be maintained in each combustion zone and so that substantially uniform or different firing conditions may be maintained in the locality of each burner port. In this manner independent control is exerted over the heating conditions about fluid conduits I I, I3, and I as compared with the heating conditions employed about the fluid conduits l2, l4, and I5" and also means are afforded for employing substantially the same or for varying the heating conditions about different portions of each of the fluid conduits II and I2.

Predominantly radiant heat is supplied to opposite sides of each tube of banks II and I! by direct radiation from the materials undergoing combustion in combustion zones I and 8, respectively, and from the hot refractory wallsof the furnace. The tubes of banks l 3 and II are heated on one side by direct radiation from the materials undergoing combustion and the hot refractory walls of the furnace and on the opposite side ,by

radiant heat reflected from the floor. The tubes.

of bank l5 are subjected to heating on one side by direct radiation from the materials undergoing combustion and the hot refractory walls of the furnace and on the opposite sideby radiant heat reflected from the roof. Eachof the tube banks and particularly bank l5 are also subjected to appreciable heating by convection. The hot combustion gases pass from combustion and heating zones 1 and 8 over bridge walls 5 and 6, respectively, to commingle above fluid heating zone 9 and the commingled gases pass downward through this zone imparting fluid heat to the tubes of bank IS with which they come in contact. The combustion gases may pass from fluid heating zone i through flue 19 to a suitable stack (not shown).

It will be apparent from theabove that the heating conditions obtained in tube banks ll, l3, and I5 are the result of the conditions of firing employed in combustion and heating zone I while the heating conditions employed about tube banks I2, l4, and I5" are the result of the conditions of firing employed in combustion and heating zone 8. Also, the heating conditions obtained in tube banks l5 and I6 are the result of the conditions maintained in both of thecombustion and heating zones I and 8. Therefore, the heating conditions and rates of heat input obtained in tube banks l5"' and [6 are not controllable, independent of the heating conditions maintained about other portions of the fluid conduit. However, tube banks such as l5' and/or 16 greatly improve the thermal efliciency of a furnace of the nature disclosed, since they permit the use of lower flue gas temperatures and, preferably, in the present invention tube banks l5 and/or 15" are employed in that stage of the heat treatment wherein accurate control of the heating condistructure above described and illustrated, the various tube banks in each of the Figs. 2, 3, and 4 are designated by the same reference numbers as in F18. 1.

Fig. 2 is representative of the type of flow which 5 may be employed for simultaneously subjecting two separate substantially equal streams of the same oil to substantially equal heating conditions. The stream of total oil to be heated is supplied from any suitable source through line 24 and 10 is divided into two substantially equal streams which pass through lines 25 and 25', controlled by the respective valves 26 and 26', into equal sections l6 and "5'', respectively, of fluid heating bank l6. Each stream of oil passes in a general upward direction through this bank of tubes countercurrent to the general direction of flow of the combustion gases passing through this zone of the furnace, the oil from bank l6 passing from the uppermost row of tubes of this bank through line 21 into tube bank l5, flowing through adjacent tubes of this bank in series in a general direction countercurrent to the direction of firing, while the stream of oil from tube bank l6" passes in a similar manner through line 25 21' and tube bank I 5". The stream of oil from tube bank I5 is transferred through line 28 to tube bank l3, flowing in series through adjacent tubes in this bank to be transferred therefrom through line 29 to the upper portion of tube bank 3,0 I I. -In a similar manner, a stream of oil from tube bank l5" passes through line 28' to tube bank l4, flowing in series through adjacent tubes in this bank to be directed therefrom through line 29' to the upper portion of tube bank I 2. The two sepa- 35. rate streams of oil pass through adjacent tubes in alternate. rows of the respective tube banks H and I2. in a general direction concurrent to the direction of firing, and are discharged therefrom through the respective lines 30 and 30' to'40.

subsequent portions of the system not pertinent to the present invention, the two streams of oil preferably being commingled shortly after their discharge from the furnace.

In Fig. 2, by controlling the flow of the oil supplied to the heating coil so that substantially the same quantity of oil is continuously supplied to each of the two separate streams and by maintainingsubstantially uniform firing conditions in each of the combustion and heating zones eachof the two separate streams of oil may be subjected to substantially equal hea'fing conditions. Fig. 3 illustrates one of the many specific forms of flow which may be employed for the treatment of a single type of hydrocarbon oil employing a single stream and series flow throughout the heating coil. The oil to be treated is supplied through line 3| to tube bank l6 flowing in series through adjacent tubes and adjacent rows of tubes in this bank in a general upward direction countercurrent to the general direction of flow of the combustion gases through this zone of the furnace. The oil passes from the uppermost row of tube bank I 6 through line 32 to one end of tube, bank l5, passing in series through adjacent tubes of this bank to its opposite end from which it is directed from line 33 to tube bank l3 wherein it flows in series through adjacent tubes in this bank and from which it is directed through line 34 to the upper portion oftube bank II. The oil flows in series through the tubes of bank II which, in the case here illustrated, comprises a single vertical row of horizontal tubes, and is directed therefrom through line 35 to and through tube bank It, passing through the adjacent tubes of this bank in series and being directed therefrom from line 36 to the lower portion of tube bank I: wherein the oil passes in a general upward direction through adjacent tubes in alternate rows of this bank to be discharged from the upper portion of tube bank I! through line 31 to subsequent portions of the system not pertinent to the present invention.

In Fig. 3, by employing more severe heating conditions in the combustion zone on the left hand side of the furnace (adjacent tube banks H and I3) than in the combustion zone on the opposite side of the furnace (adjacent tube banks I2 and it) the oil undergoing treatment may be subjected to a substantially progressive increasing rate of heating from the time it enters the furnace until it leaves tube bank It and may then be subjected to what are ordinarily termed soaking' conditions in tube banks It and i2. This type of treatment has been found particularly desirable for relatively low-boiling distillates such as straight-run gasoline, naphtha, pressure distillate bottoms and the like.

Fig. 4 illustrates one of the many forms of flow which may be employed for the simultaneous treatment of two separate streams of difierent hydrocarbon oils, each stream being subjected to independently controlled heating conditions. One stream of oil enters the lower portion of tube bank It through line 38, passing in series through adjacent tubes and adjacent rows of tubes of this bank in a general upward direction, it then passes. from tube bank It through line 39 to tube bank l3 through which it flowsv inseries through adjacent tubes and is then directed through line 40 to the upper portion of tube bank H. The oil passes in series through adjacent tubes in alternate rows of tube bank I I in a general direction concurrent to the direction of firing and is directed from the lower portion of bank ll through line H to the left-hand side of bank l wherein it passes in series through adjacent tubes of this bank in a general direction concurrent to the general direction of flow of the combustion gases, to be discharged from the right-hand sideof this bank through line 42 to subsequent portions of the system not pertinent to the present invention; The other stream of oil, of dlfierent characteristics, which is to be simultaneously subjected to independently controlled heating conditions of the same furnace, is directed through line 43 to the left-hand side of tube bank I5" passing in series through adjacent tubes of this bank in a general direction countercurrent to the general direction of flow of the combustion gases. The oil then passes from the right-hand side of tube bank 15" through line 44 to one side of tube bank I4, flowing in series through adjacent tubes of this bank to the opposite side thereof from which it is directed through line 45 to the upper portion of tube bank I 2. The oil then passes in a general downward direction through adjacent tubes in alter-' na-te rows of tube bank ii to be discharged from the lower end of this bank through line 45 to subsequent portions of the system not pertinent to the present invenion.

A flow, such as illustrated in Fig. 4, may be utilized to advantage, for example, by subjecting an intermediate oil such as, for example, reflux condensate, gas oil or the like to conversion under relatively severe heating conditions by passing it in series through tube banks l6, l3, II, and I! while employing somewhat milder heating conditions for the treatment of higher boiling oil such as crude oil, topped or reduced crude, 5

fuel oil or residual oils generally, which higher boiling oil is passed in series through tube banks l5", l4, and I2.

It will be understood, of course, that the present invention is not limited to the specific form of furnace illustrated and above described nor to the specific form of fluid conduits provided in the furnace illustrated nor to any or all of the three specific flows through the fluid conduits illustrated and above described. For example, either or both of tube banks II and I2 may comprise a single row instead of a double row of tubes and any one or more of the various tube banks l3, l4, and I5 may comprise twoor three parallel rows of tubes instead 01' a single row. The flow through the fluid conduits may also be so arranged, when desired, that more than two streams of the same fluid may be heated simultaneously each under substantially equal heating conditions or so that more than two streams of 35 diiferent fluid may be heated simultaneously, each stream being subjected, when desired, to different heating conditions.

I claim as my invention:

1. In a furnace having walls forming a combustion and radiant heating zone, the combination of fluid heating means, comprising a vertical row of horizontal tubes, centrally disposed in said zone, a horizontal row of serially connected, horizontal tubes in the lower portion of said zone beneath said fluid heating means, a second horizontal row of serially connected, horizontal tubes in the upper portion of said zone above said fluid heating means, and means for supplying fuel and air to said zone on opposite sides of said fluid heating means.

, 2. In a furnace having a pair of spaced vertical walls, a roof and a floor, the combination of a vertical row of horizontal tubes between and spaced-from said walls, a horizontal row of serially connected, horizontal tubes adjacent the roof above said vertical row of tubes, a horizontal row of serially connected, horizontal tubes adjacent the floor beneath said vertical row of tubes, and means for burning fuel in the space between said vertical row and each of said walls.

3. A furnace comprising walls forming a pair of combustion zones and a convection heating zone, heating tubes in the convection zone and means for passing combustion gases from both said combustion zones through the convection zone, a vertical row of horizontal heating tubes in each of the combustion zones, means for firing each of the combustion zones on opposite sides of the vertical row of tubes therein, a horizontal row of heating tubes in the lower portion of each of the combustion zones below the vertical row of tubes therein, and a horizontal row of tubes in the upper portion of the furnace and having tubes disposed in each of the combustion zones.

4. The furnace as defined in claim 3 further characterized in that the convection zone is positioned between the combustion zones and in that the horizontal row of tubes in the upper portion of the furnace includes tubes disposed above the 70 convection zone.

JACOB BENJAMIN HEID.

DISCLAIMER 2,046,897.Jac0b Benjamin Hez'd, -Chicag0, I11. HEATING OF FLUIDS. Patent dated July 7, 1936. Disclaimer filed September 11, 1937, by'the patentee;

the assignee, Universal Oil Products Company, assenting. Hereby enters this disclaimer to claims 1, 2, and 3 of said patent.

[Ofiicial Gazette October 5, 1937.]

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