US2184465A

US2184465A - Furnace for heat treating carbonaceous material

Info

Publication number: US2184465A
Application number: US223645A
Authority: US
Inventors: Cecilio L Ocon
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-08-08
Filing date: 1938-08-08
Publication date: 1939-12-26
Anticipated expiration: 1956-12-26

Description

C. L. OCON Def; 26, 1939.

FURNACE FOR HEAT TREATING CARBOACEOUS MATERIAL Filed Aug. a, 195;; 3 sheets-sheet 1 I N VENTOR. um

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FURNACE FOR HEAT TREATING CARBONACEOUS MATERIAL 3 Sheets-Sheet Filed Aug. 8, 1,938

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C. L. OCON Dec. 26, 1939.

FURNACE FOR HEAT TREATING CARBONACEOUS MATERIAL 3 Sheets-Sheet 5 Filed Aug. 8, 1938 .wiwi ////////////////////////////V///4w XS Nb we@ iQ mb Rumi INVENTOR,

Patented Dec. 26, 1939 FURNACE Fon HEAT 'renferme oA anni BONACEOUS MATERIAL Cecilio L. Ocon, Yonkers, N. Y.

Application August 8,

17 Claims.

This invention relates to a novel furnace construction and its operation for heat treating carbonaceous materials. It relates more particularly yto a compact furnace unit designed for heating several streams of materials to diiferent degrees of intensity and duration in several compartments arranged with improved coopera tion toward heat conservation and regulation.

Conventional furnaces hitherto used for heating petroleum oils were principally designed to heat these oils in one or two streams to cracking temperatures before they are discharged intoan enlarged separation zone. These furnaces are designed conventionally to consist of a radiation or combustion section containing the firing means and a convection section separated therefrom by a vertical partitioning or bridge wall extending from the floor to a height short of the roof. In these furnaces the oil stream is preliminarily heated in the convection tubes located in the down-draft convection section, ,then heated to a cracking temperature in the tubes located inthe combustion section. The ue gases originating in the combustion section pass over y the partitioning bridge wall and down through the convection section to the stack. Many attempts were made to modify this conventional type of furnace when requirements for more intense and controlled `neatin T of certain special types of oils came into existence. Recycling of nue gas, enlarging of the furnace, complete enveloping of the combustion flame by refractory material to avoid simultaneous radiation and convection heating are among the usual modifications.

' An object of this invention is to provide an economical and compact tube still furnace in which different oils can be simultaneously heat treated to required degrees of intensity and with precision control, using convection and radiation heating in an eflicient concerted action. In accordance with this object, a satisfactory control of radiation heating is obtained with greater uniformity than is obtained when the radiation heating is totally separated from convection heating or does not cooperate properly therewith. Further objects will become apparent from the following parts of this speciiication.

Some of the prominent features included in the present novel construction are as follows:

` (l) A uniformly intense radiation heating cb.

'(2) A superstructure for economizing on both 1938, Serial No. 223,645,v (Cl. ISG- 116) convection and radiation heat directed toward the furnace roof;

` 3) Structures for directing relatively cool combustion products over radiation heat absorbingtubes to eiciently temper the heat absorption;

(4) Structures for controlling the velocities of perature control; and

(5)2 Tube and gas duct arrangements for mak- 7 ing an eliicient use of heat generated in the several furnace compartments. The preferred mode of construction and operation will be fully understood from the following descriptions made with references to the drawings. Figure 1 shows a diagrammatical cross section of the furnacein an elevation view.

Figure 2 shows a diagrammatical cross section of the furnace illustrated in Figure l, withl some modications in bafe arrangements. y Figure 3 shows a diagrammatical cross section of section C of the furnace illustrated in Figure 2, with some modifications in tube and baffle arrangements.

In Figure l, insulated end walls of the furnace are designated by 'thenumeral l, and the floor by 2. The lower part of the furnace, or furnace proper, is shown to be partitioned into three main compartments or sections by depending baffle walls 3 and 4spaced above the `door, nainen fly, the end or louter compartments B and C, and a central compartment A, for relatively intense radiation heating. Firing means, such as one or a plurality of burners 5 extend under heating tube sections B and C through the end walls Ports for introducing combustion supporting ina l terial, such as air, together with fuel injector may be considered as making up the firing means, but also a steam injector t, may be desirably located on the under side of the burner. The 4burners y5, are preferably directed to project names against gas deecting structures l, projecting upwardly from the iioor, the combustion gases being advantageously guided by refractory baiiles 8, located above the burner and extending below each of the tube heating sections B and C. Additional steam ymay be introduced through injection jetsS, above the iloor, rto aid 4in conrpleting the combustion, to aid in directing prode ucts of the combustion into the central section A, and to control the temperature .of the combustion gases. Products of combustion passing fromunderneath bales t, are directed upwardly by structures. 'l to pass along the surfaces of partitions 3 and 4 facing toward compartment A and contiguous to a radiant flame projected upwardly through the center of section A by ring means I8, located at the base of section -A. The combustion products from combustion in the side sections directed in this manner through section A part of which has been relatively lowered in temperature, act as gaseous screens which prevent contact of the central flame with wall tubes II and I2, located in close proximity to the partitioning walls 3 and 4, respectively. The hanging arch I3 is a mass of refractory material, porous in nature, preferably hollow and constructed to permit entrance of small amounts of combustion supporting material into combustion gases impinging on the arch in order to cause some secondary combustion. The arch also functions to radiate from its surface toward a large part of the upper surfaces of wall tubes II and I2 for promoting equalization of the radiant heat absorption of these tubes.

Above the furnace proper is a superstructure I5 extending substantially over the outer sections B and C and over the top outlet from section A. The horizontal floor baie 43 of the superstructure above tube heating compartments B and C preferably may have gasl passage slots 44 to-permit free circulation of combustion products over ceiling tubes 29 and 32, which receive radiant heat in these compartments, thus preventing any stagnant gas pockets surrounding these tubes. The superstructure functions to recover a large amount of the sensible heat contained in the flue gases as they pass from the furnace to the stack outlet I6, from the superstructure I5. The side and end walls of this superstructure may conveniently be the extensions ofthe side and end walls of the furnace proper, and streamlining structures I'I are benecially used to aid the continuous circulation of the flue gases. The baiiie I8, above the arch I3, and spa-ced between the baffles 43 and the roof, extends substantially horizontally through a large part of the superstructure, acting to divide the flow of flue gases, to reflect back a large proportion of radiant heat which escapes above the roof of the furnace proper, and, with the tubes located in the two sides of the superstructure, to extract more of the sensible heat remaining in the freely circulating ue gases passing through the openings spaced between the ends of the horizontal baffle and the streamlined structures II to the stack.

Flue gases emerging from the superstructure pass freely to the stack through outlet duct I 6, due to their relatively free motion and their natural tendency to rise upwardly. With the free iiowing action of the iiue gases thus permitted additional heat extracting conduits I9 and 20, may be disposed in duct I6 to further obtain heat otherwise lost.

The central updraft furnace of this invention is admirably adapted for an under-floor air duct 22, which may be located beneath the oors below side sections B and C, to recover heat from the under part of these floors. The heat is absorbed lby the air, and the thus preheated air is drawn in by Venturi passages 26 of burner itl, located at the base of section A. The preheated air aids in making the combustion more rapid and regular particularly when a gaseous fuel introduced through pipe 3D is used in burner i3, and producing a more uniform ame which is desirable for radiant heat control in section A.

The flue gas deecting structures 1, may be fixed or may be mounted on rotatable axles (not shown) or similar means which can be set into motion for adjusting the degree to which the surfaces of these structures deflect the gases passed thereover into the central compartment.

A tube 2l located in a side Wall, as shown by the broken lines in section A, may be used to deliver preheated air from air duct 22 below the furnace floor to the interior of the mass of refractory material I3. The preheated air may permeate through the pores or small ports I4 in the refractory material to produce secondary combustion in the Yvicinity of the refractory mass surface. Air duct 22, underlying the floor, receives air through inlets 42. Additional fuel may also be supplied in the vicinity of the arch I3 by fuel injector 23. With tube 2l located in the manner shown the preheated air is readily forced upwardly by thermo-syphonic action from the air duct 22.

The secondary combustion above the central compartment is beneficial iny producing a maximum of radiant heat from the combustion gases passed `there through, also for increasing the temperature of the gases led over the soaking tubes located in the superstructure flue gas ducts.

With the furnace construction described several streams of different types of hydrocarbon or bituminous mixtures can be heated under excellent control. Steam may be passed through coil 24, from tubes I9, to provide superheated steam for processing. An initial crude charge oil may be preheated in

tubes

20 and 25. A reduced crude receives desirable \conditioning treatment by Ibeing passed through wall tubes' 21 and 28 and nally through roof tubes 29, disposed' in section B. A heavy gas oil is passed through wall tubes 3I then through roof tubes 32 to be brought up to a cracking temperature of about 850 F., and further heat treated in

superstructure soaking tubes

33 and 34. A light gas oil is rapidly brought to a vapor phase cracking temperature in partition wall tubes 35 and roof tubes 36, located in section C, then a finished heat treatment in the superstructure tubes 3'I and 38 may be discharged to a fractionating zone. A naphtha fraction may be given a very rapid and uniform vapor phase treatment in tubes Il and I2, located in the central section adjacent to the partitions and

tubes

39 and 40, in the superstructtue I5. Gas may be preheated in tubes 4I.

The partitioning baiiles 3 and 4, receive heat from sections B and C which they transmit to adjacent tubes I I and I2 by radiation mainly.

It can be readily seen that each compartment of the furnace participates in a specialized or divisional function but that all act jointly or cooperatively in exchanging kinds of heating service which Iinure to the general benefits from the entire furnace.

In Figure 2, is' shown a similar arrangement of tube heating sections and tubes as is shown in the furnace of Figure 1, but with modifications in the positioning of the partitioning baille Walls in the furnace proper which nevertheless permits a similar functioning of the furnace. In the furnace as shown in Figure 2, the flame baies' 8, may be omitted above the burners 5. The bridge walls 3 and 4 spaced below the baffles 43 which if desirable may not have the gas passage slots 44, are used in place of corresponding depending walls shown in Figure 1, making the combustion gases take a course upwardly in each of the outer compartments then over the bridge Walls 3 and 4 to join the combustion gases emerging from the central compartment A into the superstructure l5. As a substitute for the stream of combustion products passed along the Wall tubes Il and l2 in central compartment A from burners 5 as shown in Figure 1, radiant heat tempering gases suchas steam or recycle flue gas may be injected by pipes 9 disposed to project such gas between the flame and the surface of the partitioning walls 3 and 4 so as to screen the tubes from direct contact with the flame from burner I0.

By passing a combustion promoter such as nitro-organic compound in contact with ue gases owing from the combustion section the heat energy is increased securing great heating ef-` ciency by increasing the radiant heat action 4due to the complete combustion of said flue gases by the passage of combustion promoting agents selected from materials comprising nitro-organic a l and 2, double rows interconnected serially or in parallel may also be used.

compounds, e. g., propyl nitrite, and Oxy-organic compounds, e. g., ethers and resulting in less waste of heat and economy in fuel consumptionv and costs.

In Figure 3, are shown modifications in section C, of the furnace illustrated in Figure 2, in that the angularly hanging baiiles 45, which preferably may have openings or slots 46 controlled by dampers or other means, underlie the horizontal baffle 43 in a manner to increase the amount of vwhich are used to guide the products of combustion underneath sections B and C, into section A.

The present invention is intended to be utilized for `heat treating liquids or vapors of any kind or for a process requiring heat treating-various types or fractions of hydrocarbon or bituminous oils either in liquid, vapor, or mixed phase, one type or fraction being circulated through one coil while others are simultaneously circulated in adjoining coils in the same furnace, each receiving the required heat treatment under accurate control and without the necessity of separate furnaces for each type or fraction.

It is to be understood that the apparatus herein described' will be equipped with suitable indicating, recording and controlling devices wherever required for observation and accurate control of temperatures, pressures, and flow velocities throughout the furnace.

It is also to be understood that although single rows of heat absorbing tubes are shown in Figures It is also to be understood that air cooled end walls may be used if desired, and that the length and widths of the furnace, number and size of tubes, size of openings, spacings, ducts, andthe number andtypes of ring means will depend upon the designed capacity of the furnace, type of heat treating and flue gas velocities required.

The heretofore illustrated and described tube still heat treating apparatus may vary considerably and other heat treating phases may be carried out within the present invention as it is not intended that such details be regarded as limitations, for example, the disposition of tubes and flows illustrated may be varied, in fact variations, or, in some cases omissions, of certain of the component steps, may be made without departing ,i

from the scope of the invention.

I claim: -f

1. A tube still apparatus for heat treating several streams of carbonaceous material, comprising a furnace having end walls, side walls, a roof and a floor, a pair of spaced Vertical partitions dividing the furnace into two outer compartments and a central compartment, saidy partitions being disposed in a manner to allow passage of partially cooled combustion products from said outer compartments into the base of and upwardly through said central compartment, heat absorbing tubes in each of said outer compartments, Iiringmeans in said outer compartments for supplying combustible and combustion supporting material which on combustion supply radiant heat to the tubes in said outer compartments and combustion gases to be passed to said central compartment, a firing means located below the base of said central compartment for projecting a flame centrally through said central compartment and heat absorbing tubes disposed in the path of partially cooled combustion products passing upwardly through said central compartment from said outer compartments but substantially out of contact with said flame.

2. In combination with a furnace having walls, a roof and a floor, a pair of spaced partitions dividing the furnace into two outer compartments and a central compartment, means forming a convection heating zone extending upwardly from the central portion of the :furnace roof, heating tubes in said zone, radiant heat absorbing tubes in each of said compartments, firing means in each of said compartments, means for introducing non-luminous gases into said central compart-I ment for blanketing heating tubes therein from contact with luminous gases generated by the ring means in rsaid central compartment, means for merging partially cooled combustion products from the two outer compartments with combustion products developed in the central compartment, means for passing the merged `combustion products into contact with the tubes in said con# vection'zone, and means for removing the flue gases from said convection zone.

3. A tube still apparatus for heat treating several streams of'carbonaceous material, comprising a furnace having end Walls, side walls, a roof, a floor, a pair of depending partitioning walls spaced above the floor to form two outer compartments and a central compartment and disposed in a manner to allow the passage of combustion products from said outer compartments upward through said central compartment, firing means associated with said outer compartments for supplying combustible and combustion supporting materials and adapted to produce combustion which supplies radiant heat to the tubes in said outer compartments and combustion gases to said central compartment, a ring means disposed to project a flame centrally through said central compartment to increase the amount of combustion gases passing through said central compartment, heat absorbing tubes adjacent the walls and roofs of said outer compartments, and heat absorbing tubes in said central compartment disposed adjacent the walls and in the path of combustion products passed therethrough from said outer compartments but without obstructing the path of said ame.

4. Apparatus in accordance with claim 3', in which air ducts are located under the floor of the furnace, and means for supplying preheated air from said ducts to said central compartment to support combustion therein.

5. A tube still apparatus for heat treating several streams of carbonaceous materials comprising a furnace having walls, a roof, a floor, vertically disposed walls spaced above the iloor for partitioning the furnace into outer compartments and a central compartment, horizontally disposed bailles intermediate the floor and roof forming on their under sides the ceilings of said outer compartments and on their upper sides the floors of an imposed heating section through which hot flue gases pass to a duct, individual firing means associated with each of said outer compartments for supplying fuel and combustion supporting materials capable of producing combustion and adapted to supply radiant heat to the tubes in the outer compartments and gaseous products of combustion which pass through said central compartment and said imposed heating section labove said outer compartments to said duct, heat absorbing tubes disposed adjacent the ceiling and walls in each of said outer compartments, heat absorbing tubes disposed adjacent the vertically disposed walls and facing the outer compartments, heat absorbing tube disposed in the path of combustion gases passing upwardly through the central compartment, and heat absorbing tubes disposed in said imposed heating section above said outer compartments.

6. A tube still apparatus for heat treating fluid hydrocarbons flowing in conduits absorbing mainly radiant heat, which comprises a furnace having a oor, walls, and a roof, a pair of spaced baille walls for partitioning the fiunace into outer compartments and a central compartment and having radiating surfaces adjacent to said conduits located in said central compartment, a firing means for projecting a flame upwardly and centrally between said baille Walls and without contacting said conduits disposed adjacent thereto, ring means for producing combustion gases which heat the opposite sides of said baille walls, a mass of refractory material located in the path of combustion gases from the firing means projecting a flame centrally between the baille walls, and a ilue gas duct leading away combustion products which impinge said mass of refractory material.

7. Apparatus in accordance with claim 6, in which said mass of refractory material is associated with means for adding combustion supporting gases to the combustion gases as they impinge upon said mass of refractory material.

8. An apparatus for heat treating hydrocarbons comprising a furnace having side walls, end walls, a floor, a roof, and a stack, baffles protruding horizontally from the end walls and inter mediate the roof and the floor to form ceilings for two end compartments located thereunder, spaced vertical baffles partitioning a central compartment from said end compartments to allow the passage of hot gases from firing means associated with said end compartments, a horizontal baille disposed above said central compartment to form gas passages with said baffles protruding horizontally and with said roof, and said gas passages being adapted to lead iiue gases from said central compartment to the stack.

9. A tube still apparatus for heat treating several streams of fluid hydrocarbons comprising a furnace having side walls, end walls, a roof and a floor, depending spaced partitioning walls dividing the furnace into side compartments and a central compartment, a roof opening above the central compartment to allow passage of ilue gases therethrough, a super-structure disposed above said roof, a horizontally disposed baille spaced between the superstructure roof and furnace roof dividing said superstructure into upper and lower flue gas passages in such manner to allow the passage of hot flue gases flowing upwardly from the central compartment in horizontal streams through the lower and upper compartments toward a duct disposed on said superstructure through which the hot flue gases pass to a stack, firing means associated with said side compartments for supplying combustible and combustion supporting materials capable of producing combustion and adapted to supply radiant heat to heat absorbing tubes disposed in said side compartments and combustion gases to said central compartment, said heat absorbing tubes in said side compartments being disposed adjacent the roof and walls, heat absorbing tubes disposed in the central compartment adjacent the Walls and facing said central compartment, a mass of refractory material depending from the horizontally disposed baffle above the central compartment in the path of hot flue gases in a manner to radiate heat downwardly to the tubes in said central compartment, horizontally disposed baffles spaced above the oor to direct combustion products from said ilring means under said depending partitioning walls and upwardly through said central compartment, and a firing means in said central compartment to project a flame upwardly through said central compartment.

l0. A tube still apparatus for heat treating hydrocarbons comprising a furnace having a floor, end walls, side walls, and a roof, depending bailles within said furnace and spaced above the iloor to partition a central updraft compartment from adjoining compartments, firing means for producing combustion at the base of an adjoining compartment, means for directing combustion products from said ring means under said depending bafiles then upwardly through said central compartment along the depending baffles, a firing means disposed at the base of said central compartment to project a flame centrally up through said central compartment, and heat absorbing tubes disposed in said central compartment in the path of said combustion products from the adjoining compartments but free from contacting said ame projected centrally through said central compartment.

11. An apparatus as described in claim l0, in which an air duct underlies the furnace floor, and means connecting said air duct with the central updraft compartment to mix preheated air with fuel injected by said firing means disposed at the base of the central compartment.

12. An apparatus as described in claim l0, in which a mass of refractory material overlies said central compartment to form a radiant surface to direct radiation mainly toward the surfaces of the heat absorbing tubes disposed in the central compartment.

13. An apparatus in accordance With claim 10, in which a superstructure is imposed above and along said furnace roof, said superstructure having a roof, end walls, and side walls, and a floor, a horizontal baille spaced between said furnace roof and said superstructure roof to form upper and lower heating sections, openings in said superstructure spaced between said horizontal bafe ends and said superstructure end walls allowing the flue gases leaving the central compartment of the furnace to iiow in two horizontal streams outwardly, thence upwardly and inwardly through the lower and upper heating sections, a duct disposed on said superstructure roof to receive said iiue gases from said upper heating sections and leading said flue gases to astack, openings in said furnace roof forming the superstructure door to allow the passage of a portion of hot flue gases from the ring means into the said lower heating section of the superstructure, heat absorbing tubes disposed adjacent the roof and walls of lsaid adjoining compartments, heat absorbing tubes disposed in said lower heating sections, heat absorbing tubes disposed in said upper heating sections, and heat absorbing tubes disposed in said duct leading to the stack.

14. A tube still apparatus for heat treating hydrocarbons comprising a furnace having a floor, side walls, end walls, and a roof, depending baffles within said furnace spaced above said fioor to partition side compartments from an updraft central compartment and providing a passage for flowing flue gases into the base of and through said central compartment,` flue gas openings in said roof and above said side compartments to pass flue gases from said side compartments into a superstructure imposed on said furnace, said superstructure having a roof, end walls, side walls, and a floor, a horizontal baie spaced between the said furnace roof and superstructure roof dividing said superstructure into upper and lower sections, openings between the end walls and said horizontal baiie to allow the passage of ue gases from the lower to the upper section and to a duct leading to a stack, firing means associated with each of said compartments, heat `absorbing tubes disposed adjacent the ceilings and walls of said side compartments, heat absorbing tubes disposed in the path of said hot iue gases in said central updraft compartment, heat absorbing tubes disposed in the duct and said upper and lower sections of the superstructure to obstruct the passage of said hot flue gases leading to the stack.

l5. A tube still apparatus for heat treating several streams of carbonaceous material, comprising a furnace having walls, a roof, a floor, and a stack, a pair of spaced bridge walls within said furnace partitioning two outer compartments from a central compartment, each of said compartments being adapted for an updraft flow of combustion gases and merging of said combustion gases above said central compartment, means for introducing materials in each compartment which react to produce combustion gases, baffles extending above said outer compartments, said baflies being spaced apart above said central compartment to form horizontal passages for gases merged above said central compartment, a common duct leading from said gas passages to the stack, heating tubes disposed in each of said compartments, and heating tubes disposed in said gas passages and said duct.

16. A tube still apparatus for heat treating hydrocarbons comprising a furnace having a floor, side walls, end Walls, and a roof, depending baiiies within said furnace spaced above said oor to partition side compartments from an updraft central compartment and providing a passage for flowing flue gases into the base of and through said central compartment, flue gas openings in said roof and above said side compartments to pass flue gases from said side compartments into a superstructure imposed on said furnace, said superstructure having a roof, end walls, side walls, and a iioor, a horizontal baffle spaced between the said furnace roof andsaid superstructure roof dividing the superstructure into upper and lower sections, openings between the end walls and said horizontal baiile to allow the passage of flue gases from the lower to the upper section of said superstructure and to a duct leading to a stack, firing means in each of said compartments, heat absorbing tubes disposed acljacent the roof and walls of said side compartments, heat absorbing tubes disposed in the path of said hot flue gases in said central updraft compartment, heat absorbing tubes disposed in the duct and said upper and lower sections of the superstructure to obstruct the passage of said hot flue gases leading to the stack. A

, 17. A tube still apparatus for heat treating several streams of carbonaceousmaterial comprising a furnace, having a floor, a roof, a duct, side walls, and end walls, and having outer compartments partitioned by. depending baies from a central compartment, horizontal baffles protruding from said end walls connecting with said depending baffles, a superstructure imposed over said horizontal and depending baffles, and said horizontal baflies forming on the upper sides the` iioor of said superstructure and on their under sides the ceilings of said outer compartments, a horizontal baule spaced below said furnace roof and above said horizontal and depending balies to form lower and upper heating sections, openings between said horizontal balie and said end walls toV allow the passage of flue gases from the central compartment through the lower heating sections to the upper heating sections, a duct disposed on furnace roof through which said flue gases pass to the stack, firing means disposed at the base of said end walls for producing combustion and directing flames inwardly horizontally, gas deecting structures disposed on the furnace iioor, below said depending baffles in the path of the flames and combustion gases for projecting flames upwardly through said central compartment, ring means disposed-at the base of said central compartment disposed between the gas deflecting structures to project a flame centrally upward through said central compartment, horizontal refractory baffles protruding inwardlyv from said end walls and spaced between the ring means and the horizontal and depending bafwalls of said central compartment and in the path of combustion gases, heat absorbing ytubes disposed above said outer compartments in the upper and lower heating sections, heat absorbing tubes disposed above the central compartment in the duct, a mass of refractory material overlying said central compartment to form a radiant surface to direct radiation mainly towards theupper i Kfiring means.

cEcrLro L. oooN.