US2081927A - Heating process and apparatus - Google Patents

Description

A. E. HASSLER El' AL HEATING PROCESS AND APPARATUS Y June 1, 1937.

Filed Feb. 9, 1934 2 Sheets-Sheet 2 Y 2212972 ons A722772 Huy Patented June l, 1937 HEATING PROCESS AND APPARATUS Anthony E. Hassler, Ridley Park, and Hugh W.

Field, Glen Mills, Pa., assignors to The Atlantic Refining Company, Philadelphia, Pa., a

corporation of Pennsylvania Application February 9, 1934, serial No. 710,47

(o1. 19e-11s) Claims.

'Ihe present invention relates to a heat dis-Y tributor for use in furnaces in which the tubes through which liquid to be heated is passed, are disposed vertically and in concentric relation to 5 the source of heat.

Our invention is particularly applicable to furnaces of the de Florez type in which the liquid entering the tube system passes alternately upwardly and downwardly through the adjacent lo tubes parallel to the flow of combustion gases until it has traversed the entire circle of the tubes and is withdrawn therefromat a point adjacent to point of introduction. Such furnaces are used for heating hydrocarbon oils, particul5 larly petroleum oils in the production of gasoline from heavier hydrocarbons by thermal decomposition or cracking. 'In cracking oils in furnaces of this type it is desirable to maintain a careful regulation of the heat input to the oil tubes in 20 various sections of the furnace but ythis is not possible in the ordinary typeof construction. We have found that the heat input may be controlled, and by so doing we have been able to increase the cracking performance of the furnace by bringing the oil to the cracking temperature more rapidly, thus increasing the amount of cracking per cycle on the oil passing through the furnace since the oil is at-the cracking temperature for a longer portion of its travel through the tubes.

Furnaces of the de Flores type are generally.

constructed with a number of liquid or gaseous fuel burners, usually 3 or 5 located either at the top or the bottom of the furnace and concentric with respect to the tubes. Heretofore, the conventional method of controlling the temperature in the various tube sections has been to regulate the quantity of fuel supplied to each of the several burners. In attempting A this control on the furnaces of conventional construction, we have found it extremely vdifficult to obtain the desired degree of heat distribution.

For example, the furnace under consideration may contain a series of '100 vertical tubes arranged within the periphery of the furnace wallsA and surrounding -a set of 5 burners. vThe series `of tubes may be arbitrarily dividedl for example, into y5 sections of 20 tubes each. In the event that it is found desirable to increase the heat input into the flrst 20 tubes, the fuel ow to the burner adjacent these tubes would be increased. However, due to the fact that the distance from this burner to the nearest tube is not markedly less than the distance from the. saine burner'to the tubes on the opposite side of the furnace, a considerable portion of the increased heat is absorbed by tubes other than those to which it is' desired to supply additional heat. As a result it is impossible to maintainl a substantial'variation of heat input to the several sets of tubes.

In order to overcome this diculty and to effect the desired control of heat input to the various tube sections in the furnace, we provide a heat deflecting surface adjacent each of the several burners so that the radiant heat therefrom vmay be directed to the proper tube section. The

heat deecting surface may be constructed of refractory material, such as re brick or heat resistant alloy steels, and of such height that the radiant heat from each burner is' reflected to the tubes nearest that burner, while the major portion of the radiant heat is prevented from passing across the furnace and affecting the other tubes. The deflecting surface is preferably of such height that the entire length of the tube section which it is desired 'to hide from the flame from any particular burner will be protected. If, for any reason, it may be desirable to heat the upper portion of the tube section to a'greater extent than the lowerv portion, the height of the deilecting surface may be reducedso that the upper portion of the tube section is exposed to radiation from any burner in addition to the one adjacent the particular tube section. Or, if it is desired that an increased amount of the radivant heat from the several burners be reflected to the upper portion of the' tube sections, the defleotor surfaces may be sloped to form, .for example, a polygonal truncated pyramid.

For a further understanding of our invention, reference is made to the accompanying drawings, Fig. 1 of which illustrates one form of apparatus suitable for effecting heat control.

The furnace comprises a vertical metal shell I supported by members 2 and lined with a heat insulating material 3 such as, for example, insulating bricks. tected from combustion gases by a facing of refractory brick 4, i. e., fire brick. Disposed within the surface is a series of tubes l5 connected by means of headers 6, said tubes being concentril cally arranged with respect to the source of heat.

The furnace is provided with a flue 1 within The insulating material 3 is prowhich is disposed a series of tubes 8 which function as a preheating section for the liquid Ato bc introduced into the tubes 5. The fui-haceis heated by means of a plurality of burners whose outlets may be represented by the orices 9. Fuel, in the form of oil or gas, is supplied to the burners thru valve-controlled pipes l0 and the air necessary to support combustion is drawn into is injected into the furnace thru the orifices 9, and the resulting combustion supplies heat@ 'the tubes 5.

In order to control the distribution of heat in any desired section of the furnace tubes, a heat deflecting surface I2 is disposed adjacent to each burner orifice. This surface provides a means whereby the radiant heat from each burner is concentrated in that section of the furnace nearest the deecting surface. The heat deiiector is preferably constructed in such a manner that the point of maximum heat of the burner flame is approximately midway of the length of the deiiecting surface. The upper portion of the defiector thus shields the tube section on the oppositeside of the furnace from the radiant heat of the burner adjacent the defleoting surface. 'The deflector is preferably constructed of refractory material, with a deflecting surface for each burner. Each surface may be further defined by means of fins I3, extending either partially or totally `the vertical length of the deflecting surface. Furthermore, the fins I3 may be extended horizontally in the direction of the conical refractory wall forming the base of the furnace, thereby more closely confining the heat, from each of the several burners to their respective sets bf tubes.

Referring to Figs. 2 andr3 of the drawings,

' impinging upon the refractory furnace walls 4 or heat-deflecting surfaces I2 and I 3 arereiiected to a substantial extent, as shown by the broken lines. For simplicity, the once reected rays only. are shown; actually reflection may occur 3 or 4 or more times before absorption is effected. A

The heat concentrating effect of the deector is clearly illustrated in Fig. 2, substantially all of the rays being confined to that section of the furnace adjacent the burner and deflector wall under consideration. At the same time the deilec'- tor functions to prevent heat from the remaining burners from impinging to substantial extent upon the furnace tube sections other than those atacent said remaining burners.- By maintaining a greater heat input vin that section of the furnace adjacent the uid inlet, such fluid may be brought rapidly to the desired temperature shortly after its introduction into the tube system, without increasing to an undesirable extent the lheat input to the other furnace tube sections. Thus, our heat deflector functions to concentrate the heat in any desired section of the furnace, and simultaneously shields the non-adjacent sections to substantial extent.

Fig. 3 shows a furnace in which `no heat deflector has been installed, and it will be seen that since there is no means for directing the heat input to any particular section of the furnace, an increase in heat input from any burner will be distributed thruout the fiu'nace and it is therefore impossible to regulate the distribution to give satisfactory or desired results.

It will be seen that the increased firing of one or more of the burners will result in an increase in heat input to the furnace, and by the em- 5 ployment of our deiiecting device the resulting heat may be directed to the desired tube section of the furnace. y

As an example of the improved results obtained by means of our invention, in cracking an over- 10 head fraction from the Texas cru'de in a furnace having a. plurality of vertical tubes arranged in circular fashion around the burners without the employment of the'heat deflecting device, 68% of the path of fiow'was traversed by the oil 15 before it'attained a temperature of 950 F.; when a five faced deector was installed in accordance with our invention and the burners adjusted to give the maximum heat in the earlyheatingstages the oil reached 950 F. when it had traversed 20 45% of the path and, since it was at the cracking temperature for a longer portion of its path through the furnace, the quantity of motor fuelv produced per day was increased 36% over the quantity Produced by the same still without em- 25 ploying our invention.

While we have illustrated our invention show-l ing a pentagonal form of heat deiiector, we do not intend to limit ourselves thereto but consider within the scope of 'our invention a deector of 30 any shape adapted to shield one/l or more tube sections. Furthermore, while our invention is described with particular reference to a furnace adapted for heating hydrocarbon oils, it is to be understood that our heat deflector is applicable 35 to any furnace equipped with'vertical tubes arranged in a circular manner, regardless of the nature of the fluid which is to be heated. For example, it may be used in apparatus for the. generation of steam. It is further to be understood that the iin type structure built out from each deflecting surface, While generally of material advantage, may be dispensed with if desired.

What we claim is:

1. In a furnace having a' plurality of vertical heat absorbingtubes disposed therein about the peripherythereof, a multi-faced, relatively nonabsorbing heat defiector positioned centrally of said tubes, fins of relatively non-heat absorbing material extending radially from the vertical boundaries of the deflector faces, and a burner adjacent each heat deflecting face, whereby radiant heat from each burner is directed to the tubes immediately adjacent each deflecting face.

-2. A method for heating hydrocarbon fluids which comprises passing the fluid to be heated about the periphery of a heating zone in a series of relatively short alternate upward and downward paths, supplying heat from a; plurality of sources located centrally of said heating zone, varying the supply of heat to the fluid as it passes thru said path .by maintaining a differential between the intensities of heat at the several sources, and causing heat from each of said sources to impinge substantially uniformly upon that portion of said path adjacent thereto, while preventing heat from any of said sources from impinging to substantial extent upon any portion of the path other than that adjacent thereto.

3. A method for heating hydrocarbon fluids 70 which comprises passing the fluid to be heated about the periphery of a heating zone in a series of relatively short alternate upward and downward paths, supplying heat from a plurality of sources located centrally of said heating zone, 7i

"the heating zone and rapidly vto the cracking temperature.A

to the iiuid as it the ingreater varying che supply of nest passes thru'aaid pathrby maintaininl tensity ot heat at one of said sources than that at another,.and causing heat from each of said sources to impinge substantially uniformlynpon that portion of said path adjacent thereto, while preventing heat from-any of said sources from imping'ing to substantial extent upon any portion of the path other 'than that adjacent thereto.

higher-.intensity of heat of heat adjacent the point of introduction of oil to the circular path than is maintained in thesources of heat adjacent the point of withdrawal -oi .the oil from the circular path and shielding the last-named portion of the circuthe heating zone lar path fromv the heat evolved at the source of heat adjacent the tiret-named portion o the circular path. i

5.1m the art ot cracking petroleum,the steps which comprise passing the oil in a circular path about the periphery of a heating zone in a seriesvo! relatively short alternate upward, and downward paths parallel 'to the now of combustion products passing from a plurality of sources of combustion arranged centrally of tothe cracking temperature by maintaining a higher intensity of rheat in at least one source of vheat adjacent the point of introduction oi oil to the circular path than is maintained in the sources of heat adjacent the point of withdrawal of the oil tronithe circular path and shielding the last-named portion of the circular path from the heat evolved at the source of heat adjacent the mst-named portion of the circular path and supplying sufllcient heat to the .oil from the remaining sources of heat to maintain it at least at the cracking temperature.

ANTHONY E. HASSLER.

HUGH W. FIELD.

and rapidly bringing the oil` v

Images