US2346345A - Heater for fluids - Google Patents

Description

April 11, 1944. Q A L I 2,346,345

HEATER FOR FLUIDS Filed Feb. 20, 1942 #BlZPNERS BURNEPS Y\ o O 0 82 9 20 10 O Q0 0 o B 20 o 20 o 2/ O Q g o O O O 0 g o o 0 O O O facing the tube banks in the side Patented Apr. 11, 1944 HEATER FOR FLUIDS Charles H. Angeli, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 113., a

corporation of Delaware Application February 20, 1942, Serial No. 431,703 Claims. (01. 122-356) This invention relates to an improved form of heater for fluids which is particularly advantageous as applied to heating hydrocarbons to the high temperatures required for their thermal or catalytic conversion. It to heating other fluids and will be useful whenever it is desired to heat one or more streams of the same or different fluid under substantially the same or under different heating conditions and with relatively high rates of heat input.

The heater provided is of the type employing a plurality of separately flred cells or radiant heat ing zones in which flames and hot combustion gases from the firing means are passed vertically over the surface of thereby heated 'to a highly radiant condition, radiant heat being transmitted directly from said wall and from the flames and hot combustion gases passing thereover to the tubular elements of the fluid conduit disposed within said cell.

In one specific embodiment of the invention the heater comprises exterior refractory side and end walls, a floor and a roof and vertically disposed interior refractory walls extending between the end walls and from the floor to an elevation somewhat beneath the roof. These interior walls are spaced from each other to provide a centrally disposed cell or combustion and radiant heating zone therebetween and a vertically disposed bank of tubes is located substantially midway between the interior walls in said central cell, The interior walls are also spaced fromthe side walls to provide another cell or combustion and radiant heating zone between each interior wall and the adjacent side wall. A vertically disposed bank of tubular fluid conduits is located in each of the last mentioned cells adjacent the surface of the interior wall and a fluid heatirig zone containing a bank of tubular fluid conduits is disposed beneath and in direct communication with each of the last named cells. A row of burners is disposed adjacent the base of each of walls for projecting flames and hot combustion gases upwardly through the central cell over and in intimate contact with the surface of themterior walls facing said centrally disposed tube bank. A row of burners is disposed adjacent the top of each of said side walls for projecting flames and hot combustion gases downwardly over and in intimate contact with the surfaces of the latter cells. Compass over the side cells and bustlon gases from the central cell top of said interior walls into the thence downwardly therethrough and combustion gases from each of the side cells are directed is, however, well adapted a refractory wall which isthe interior 4 through the communicating fluid heating zone and thence from the heater through flues communicating with the stack.

Various modifications of the specific form of heater, above described, are within the scope of the invention, as willbe subsequently explained.

The accompanying diagrammatic drawing represents a sectional end view of one specific form of the heater provided by the invention and its features and advantages will be more apparent with reference to the following description of the drawing.

The heater hereillustrated tially vertical refractory side walls I and 2, a refractory roof 3, a floor 4, end walls (not shown) and foundation walls 5, 6, 1 and 8.

Substantially vertical comprises substanspaced from each other A centrally disposed flred' cell or combustion and radiant heating zone I I is provided between walls 9 and In. Another independently fired cell or adJacent the floor 4 to adjacent the upper exsubstantially vertical row of horizontally disposed is located in zone 42 adjacent the surface of wall 9. Another tube bank 23, also comprising, in this instance, a single substantially vertical row of horizontally disposed tubes 24, is located in zone 43 adjacent the surface of wall it. Another tube bank 25, comprising a plurality of superimposed horizontal rows of horizontally disposed tubes 23, is located in fluid heating zone It and a similar bank 21 comprising a plurality of superimposed horizontal rows or horizontally disposed tubes 23, is located in, fluid heating zone IS.

A row of bumers, one of which is indicated at 29, is disposed within burner compartment i8 adjacent the base of wall 9 and another tow of burners, also designated by the reference numeral 29, is disposed in zone l8 adjacent the base of wall l0. Firing ports 30 are provided in floor I for the burners 29 and flames and hot coinbustion gases are directed upwardly from the burners and burner ports over and in intimate contact with the surfaces of walls 9 and i through zone I. These walls are thereby heated to a highly radiant condition and radiant heat is transmitted directly from the walls and from the flames and hot combustion gases passing thereover to the tubes of bank IS. The tubes in each row of bank I! are staggered with respect to the tubes in the other row thereof so that each tube receives radiant heat on one side from wall 9 and from the flames and hot combustion gases passing thereover and on its opposite side from zone ill and the flames and hot combustion gases passing thereover.

Combustion gases which have given up a substantial portion of their radiant heat to the tubes of bank I9 pass from zone between the upper ends of walls 9 and I0 and the roof 3 into zones i2 and I3. Preferably, to maintain substantially stream-line flow, and to assist in substantially equally dividing the combustion gases tions to which each of the tube banks l9, 2| and- 23 is subjected, are controlled independently of the heating conditions for the other tube banks of this group and that banks 2| and 23 may be subjected to substantially identical or to different heating conditions. Also, the heating conditions about tube bank 25 are controlled independently of those about tube bank 21. This construction and arrangement makes the heater exceptionally flexible with respect to contro1 of the heating curve for the fluid undergoing treatment and,

from zone Ii between zones i2 and I3 and direct said gases toward the surfaces of walls I and 2, the interior surface of roof 3 is curved, as illustrated in the drawing, with a bull-nose 3| projecting downwardly into the space immediately above zone II and tube bank l8.

The combustion gases from zone H which are directed into zone |2 pass downwardly therethrough in contact with the interior surface of wall I and their volume and temperature is increased to the desired degree as they enter zone H by the addition thereto of fresh flames and hot combustion gases directed downwardly through zone |2 over the surface of wall I from a row of burners, one of which is indicated at 32, disposed adjacent the upper end of wall I, firing ports 33 being provided for these burners in roof 3.

In the same manner, combustion gases supplied, as previously described, from zone H to zone I3, pass downwardly through the latter over the surface of wall 2 and their volume and temperature is increased to the desired degree as they enter zone I3 by the addition thereto of fresh flames and hot combustion gases supplied through burner ports 33 from the row of burners 32 disposed adjacent the upper end of wall 2.

In passing through zones l2 and I3 the combustion gases from zone H and the fresh flames and hot combustion gases from burners 32 heat the interior surfaces of walls I and 2 to a highly radiant condition and heat is supplied from these walls and from the flames and hot combustion gases passing downwardly thereover to one side of each of the tubes of the respective banks 2| and 23. The opposite side of each of the tubes of bank 2| is heated by reflected radiation from the adjacent surface of wall 9 and the opposite side of each of the tubes of bank 23 is heated by reflected radiation from adjacent wall in.

The combustion gases which have given up a in addition to permitting heating of a single stream of fluid in banks i9, 2| and 23, with greater flexibility of the heating curve employed, it permits the heating of two or more separate streams of the same fluid or of different fluids under substantially the same or under different heating conditions for each stream.

The invention is not limited to any particular sequence of flow through the various tube banks, but permits a wide variety of specific hook-ups which may be selected to suit requirements and correlated with the heating conditions employed in the various cells to give the results desired. However, the following examples are given to illustrate a few of the many possible specific flows which may be advantageously employed.

to the lower row of bank 25 and passes in series through the adjacent tubes in each row and through the several rows in a generally upward direction, being transferred from the uppermost row of bank 25 to the lower end of bank 2| and passing through the adjacent tubes of this bank in series in a general upward direction, to be discharged from the uppermost tube of bank 2|. Simultaneously, a separate stream of different fluid is passed in substantially the same manner through banks 21 and 23 and a third stream of another fluid is passed serially through the tubes of bank l9. By independent control of the heating conditions in zones l2 and i3, each of the three streams may be subjected to different heating conditions. 1

Example [I ployed for zones l2 and I3 so that each of the two streams is heated under substantially identical conditions in the respective banks 2| and 23 and in the respective banks 25 and 21. By

substantially equal firing of zone H on opposite sides ofbank l9, each ofthe streamsis also subjected to substantially identical heating conditions in the opposite rows of this bank. This type of flow is-particularly advantageous when it is desired to employ different heating conditlons' for initial-treatment of the fluid as it passes through the heating coil, as compared with'those employed at a later period in its heat treatment. For example, hydrocarbon distillate to be reformed, such as gasoline or gasoline fractions of low antiknock value, naphtha or the like, may, with this flow, be quickly heated to the desired'high cracking temperature at the outlet of coils 2| and 23 and then passed through tube bank lswhich comprises a soaking section wherein the fluid is maintained at or near the maximum temperature previously attained for a predetermined time to complete the desired reforming operation.

Example -III As a modificationof the flow given in Example II, above, thetwo streams from banks 21 and 23,

- instead of passing through opposite rows of bank l8, maybe commingled in one of the end tubes of this bank and passed serially through the adjacent tubes in opposite rows of bank I 9 in either a general upward or a general downward direction.

Example I V.

In anothermodification of the flow given in Example 11, the sequential arrangement of banks is, 2| and 23'maybe reversed, a stream'of fluid from bank 25 being-directed throughthe left hand row of bank 19 and thence through bank 2|, while a stream of fluid from'bank' 2] is'directed through the right-hand row of bank; l9 and thence through bank 23.

By employing different heating conditions in zones l2 and I3, the flow given in Example II'or the fiow givenin Example IV maynbeadvantageously employed inheating two streams. of different fluid under difierent heating conditions and to difierentoutlet temperatures, particularly when relatively mild heating conditions, as com- "pared with those employed in zones l2 and 13,

are utilizedin zone II, or vice versa, or when different heating conditions are employed on opposite sides of bank IS in zone ll.

Various modifications of the specific formofheater illustrated and above described will be apparentto those familiar with the artand are entirely within the scope of the invention. For example, bank I9 may comprise a single row or more than two substantially parallel rows of tubes'instead of the two-row arrangement illustrated. Also, two or more substantiallyparallel rows of tubes may be employed for bank 2| or for bank'23, or both, instead of the single row illustrated. The adjacent tubes in each row of the individual banks may be connected in series at their ends and adjacent rows may be connected in parallel or-in series. Alternatively, the tubes in each row or in various sections of each row may be connected for the parallel flow of separate streams of fluid therethrough and it is also within the scope of the invention to em ploy substantially vertically disposed tubes in any or all of the various banks l9, 2! and 23,

instead of the. horizontally disposed tubes.- It is also within the scope of the invention to invert the heater, firing cell II, in a downward direction'and cells I2 and I3 in an upward'direction.

One of the outstanding features and advantages of the invention resides in the provision for directing combustion gases from the central cell of-the heater-through the side cells wherein they supply a substantial portion of their residual heat to the respective banks 2! and 23' andwherein their volume and temperature is'increased to the desired degree by firing of the burners individual to cells i2 and 13. This permits good utilization of the residual radiant heat in-thecombustion gases from zone H and is particularly advantageous when more severe heating conditions are employed about bank l5 than those about bank 2! and 23. The invention is, however, not limited to firing zone l2 and B from burners 32 and,

when desired, one of the zones H or B may be the heater here shown.

Iclaim as my invention: 1. A heater for fluids comprising, in combination, a radiant heating zone disposed between a pair of substantially vertical refractory walls, a

substantially vertical bank of tubular fluid conduits disposed in said zone substantially midway between said walls, another radiant heating zone adjoining the first named zone and disposed between'a pair of substantially vertical refractory walls, a substantially vertical bank of tubular fluid conduits disposed in said other heating zone adjacent the surface of'onlygine of said refractory walls thereof, means for directing hot combustion gases through the first named zone over said 'walls thereof in direct radiant heat transmlttlng relation to the tube bank dis sed therein, means for directing hot combustion'gases through the second named zone over the surface of that'wall thereofopposite the tube bank disposed therein and in direct radiant heat transmitting relation to said'tube'bank, and means for directing combustion gases from one of said zones into and through the other of said zones.

2. A heater for fluids comprising, in combination, a radiant heating zone disposed between a pair of substantially vertical refractory walls, a substantially vertical bank of tubular fluid'conduits disposed in said zone substantially midway between said walls,another radiant heating zone adjoiningthe first namedzone and disposed between a pair of substantially vertical refractory walls, a substantially vertical bank of tubular fluid conduits disposed in said other heating zone adjacent the surface of only one of said refractory wallsthereof, means for directing hot combustion gases through the first named zone over said Walls thereof in a substantially vertical direction and indirect radiant heat transmitting relation to the tube bank disposed'therein, means for directing hot combustion gases through the second named zone over the surface of that wall thereof.

tion, a radiant heating zone disposed between a pair of substantially vertical refractory walls, a

4- asaasas substantially vertical bank of tubular fluid conthe first named tube bank, means for directing duits disposedin said zone substantially midway between said walls. another radiant heating zone adjoining the flrst named zone and disposed between a pair of substantially vertical refractory walls, asubstantially vertical bank of tubular fluid conduitsdisposed in said other heating zone adjacent the surface of only one of said refractory walls thereof, means for directing hot combustion -'gases through the first namedzone over said walls thereof in a substantially vertical'direction and in direct radiant heat transmitting relation to the tube bank disposed therein, means for directing hot combustion gases through the second named zone over the surface of that wall thereof opposite the tube bank disposed therein in, a substantially vertical direction reverse to that employed in the first named'zone and in direct 'radiant heat transmitting relation to said tube bank, and means for directing combustion gases from one of said zones into and through the other of said zones.

4. A heater such as defined in claim 1, provided with means, comprising burners disposed adjacent. one end of each of the walls over which said hot combustion gases are passed, for generating flames and hot combustion gases in each of said zones. 1

5. Aheater for fluids comprising, in combination, a radiant heating zone disposed between a.

pair of substantially vertical refractorywalls, a

substantially vertical bank of tubular fluid con.-

gases through the first named zone over the surface of said wallsthe'reof in a substantially vertical direction and in direct radiant heat transmitting relation to the tube bank disposed therein, means for directing hot combustion gases through each of said other zones over the surface of that wall thereof opposite the 'tubebank disposed therein, and means for directing cornbustion gases from the first named zone into and.

through said other zones. l

6. A heater for fluids comprising-in combination, a radiant heating zone disposed between a pair of substantially vertical refractory walls, a substantially vertical bank of tubular fluid conduits disposed in said zone substantially midway between saidwalls, other radiant heatingzones adjoining and disposed on opposite sides of the first named zone, each of said other zones being disposed between one of'said walls of the first named zone and-on opposite substantially vertical refractory wall, a substantially vertical bank of tubular fluid conduits disposed, adjacent the surface of one of said walls in each -of said other heating zones, means, comprising burners ,dis-

posed adjacent one endcf each of said walls of the first named zone, for'gene'rating flames and hot combustion gases in the flrst'named zone and for directing the same vertically over said walls in direct radiant heat transmitting relation to flames and hotcombustion gases upwardly into. the firstnamed zone over the surface of said in-- combustion gases from theend of the first'named zone opposite said burners into each of said other zones, means comprising burnersmdividual to each of said other zones for generating flames-and hotcombustion gases .therein to commingle with said combustion gases from the first 'nam'edzone and for directing the commingled gases'vertically over 'the surface of that wall in each of said other zones opposite the tube bank disposed therein and in. direct radiant heat transmitting relation tosaid tubebank.

'7. Aheater such as defined in claim 5-,- having a fluid heating zone individual to andv communieating with each of the second named radiant heating zones, 9. bank of tubular fluid conduitsin each .of said fluidheating zones, and means for directingcombustion gases from each of the sec.- ond named radiantheating zones through the communicating fluid heating zone in contact with said tube bank disposed therein.

8. A heater such as defined in claim 6, having afluid heating zone individual to and communieating with each of the second named radiant heating zones, a bank of tubular fluid conduits in each of said fluid heating zones, and means for directing combustion gases from each of the second named radiant heating zones through the communicating fluid heating zone in contact with said tube bank disposed therein.

9. A heater for fluids comprising, in combination, refractory side walls, end walls, a floor and a roof, interior walls spaced from each other and extending from saidfloor to an elevation beneath said roof to provide a radiant heating zone therebetween, said interior walls also being spaced from..said.side walls to; provide.a separate radiant heating zone between each interior wall and the adjacent side wall, a substantially vertical bank of tubular fluid conduits disposed in the first named radiant heating zone substantially midway between said interior walls, a bank of tubular fluid conduits disposed in each of said separate radiant heating zones adjacent said interior wall thereof, burners disposedadjacent the.

base of each of said interior walls for directing terior walls facing the first namedtube-bank, burners disposed adjacent the upper end of each of said side walls for directing flames and hot combustion gases downwardly through each of said separate radiant heating zones over the surfaces'of said side walls which face the second named tube banks, means for directing combustion gases from the first named zone overthe upper ends of said interior walls into each of said separate zones and means for removing combustion gases from the lower end of each of said separate radiant heating zones. 1103A" heater such as defined in claim-9, having a fluid heating zoneindividual to and commnnicating with each of said separate radiant heating zones, a bank of tubular fluid conduits in each of said fluid heating zones, and means for directing" combustion gases from each of said separate radiant heating zones through the com.-

municating fluid heating zone in contact with said tube bank disposed therein.

- CHARLES H. ANGELL.

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