US3663645A

US3663645A - Liquid quench

Info

Publication number: US3663645A
Application number: US7707A
Authority: US
Inventors: Rolf K Dorn; Maldwyn J Maddock; Salvatore A Guerrieri
Original assignee: Lummus Co
Current assignee: Lummus Technology LLC
Priority date: 1970-02-02
Filing date: 1970-02-02
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16
Also published as: JPS5417181B1; DE2104478A1; NL7101077A; GB1344641A

Abstract

A METHOD AND AN APPARATUS FOR QUENCHING HOT GASES OBTAINED IN TREATMENT OF HYDROCARBONS. A STREAM OF HOT GASEOUS HYDROCARBON ISSUES FROM A REACTOR AND IS CONVEYED IN A CONDUIT. IN THE IMMEDIATED VICINTY OF THE OUTLET CONNECTING THE REACTOR WITH THE CONDUIT THE LATTER IS PROVIDED WITH A LONG RADIUS BEND OF AT LEAST APPROXIMATELY 45* TO FACILITATE THE INJECTION OF COOLING LIQUID CONCURRENTLY AND COAXIALLY INTO THE STREAM OF HOT GASEOUS HYDROCARBONS WITHOUT OBSTRUCTION OF THE FLOW PATH FOR THE HOT GASEOUS HYDROCARBONS, IN ORDER TO AVOID ANY FLOW DISTRUBANCE OF THE STREAM OF HOT GASEOUS HYDROCARBONS PASSING THROUGH THE CONDUIT. DOWNSTREAM OF THIS BEND THE CONDUIT DIVERGES TO CONSTITUTE A DIFFUSOR. THE BEND IS ASSOCIATED WITH AT LEAST ONE FLUID-INJECTING NOZZLE WHICH INJECTS THE COOLING LIQUID, SUCH AS RECYCLED OR RECIRCULATED HYDROCARBONS, INTO THE OUTLET PORTION OF THE BEND.

Description

May 16, 1972 R. K. DORN ETAL LIQUID QUENCH 2 Sheets-Sheet 1 Filed Feb. 2, 1970 F/G. I

May 16, 1972 R. K. DORN ET AL 3,663,645

LIQUID QUENCH Filed Feb. 2, 1970 2 Sheets-Sheet 2 United States Patent cc 3,663,645 Patented May 16, 1972 US. Cl. 260-683 19 Claims ABSTRACT OF THE DISCLOSURE A method and an apparatus for quenching hot gases obtained in treatment of hydrocarbons. A stream of hot gaseous hydrocarbons issues from a reactor and is conveyed in a conduit. In the immediate vicinity of the outlet connecting the reactor with the conduit the latter is provided with a long radius bend of at least approximately $5 to facilitate the injection of cooling liquid concurrently and coaxially into the stream of hot gaseous hydrocarbons without o'bstruction of the flow path for the hot gaseous hydrocarbons, in order to avoid any flow disturbance of the stream of hot gaseous hydrocarbons passing through the conduit. Downstream of this bend the conduit diverges to constitute a diffusor. The bend is associated with at least one fluid-injecting nozzle which injects the cooling liquid, such as recycled or recirculated hydrocarbons, into the outlet portion of the bend.

BACKGROUND OF THE INVENTION The present invention relates generally to the quenching of hot fluids, and more particularly to the quenching of heated hydrocarbons. Still more particularly the invention relates to a method of quenching heated hydrocarbons and to an apparatus for carrying the method into effect.

In the disclosure following hereafter reference is had particularly to the quenching of heated hydrocarbons. However, while the invention is particularly well suited for this purpose it should be understood that the explanation of the invention with respect to the quenching of heated haydrocarbons is by way of example only, and that the invention is not to be considered limited thereby. It is well known that in modern chemical processes many chemical reactions are carried out at high temperatures in order to obtain a rapid reaction rate. The problems to which the present invention is directed pertain to many such chemical reactions and are well exemplified in the production of ethylene by pyrolysis of hydrocarbons, of low molecular weight.

In this ethylene production, as indeed in the other aforementioned chemical reactions, it is most important to stop the reaction at a predetermined time, or to at least substantially reduce the reaction rate rapidly, in order to avoid the formation of by-products and residues resulting from secondary reactions and to thereby maximize the yield of the desired product. Thus, in the aforementioned exemplary production of ethylene, hydrocarbons are introduced into a reaction zone at a very high throughput rate, and the hydrocarbons are rapidly brought to reaction temperature and maintained at this temperature for a time period which may be on the order of a fraction of a second, and under these conditions ethylene is the primary resulting product.

It is well known, however, that if the reaction products are not cooled immediately, secondary reactionssuch as polymerization-takes place with a resulting production'of tars and coke and a reduction in the yield of ethylene. Aside from this rather evident disadvantage there is the fact that if such secondary reactions are allowed to take place, the tars and coke which are produced tend to clog and block the pipelines, valves and other components of the apparatus with resultant complicated maintanance problems and, frequently, shutdown of the plant.

lAll of these problems have of course been realized in the industry and many attempts have been made to overcome them. Despite the realization that the problems can be overcome-and the desirable results obtainedby quenching the reactor effluent by contacting it intimately with a stream of cool fluid, the large number of devices which have become known for this purpose still sufiers from various disadvantages making them less than adequate. Specifically, many of these prior art devices will not provide the rapidity and intimacy of mixing of the efiluent with the quenching fluid which is necessary. The same or other devices would use a significant pressure drop in the quenching device. Such prior art devices provide a rapid quench, but only at the expense of higher pyrolysis pressure which in turn reduces the yield of the desired product, or at the expense of lower downstream pressure, consequently requiring larger compressor devices-which are accordingly more expensive in their initial cost and in their subsequent operationfor introducing the reaction products into subsequent treating units.

A further, and perhaps the most significant deficiency of the prior art devices is the formation of coke, polymer or similar deposits if the devices are operated at temperatures facilitating the recovery of the quenched heat by generation of steam in a quench cooler. In order to avoid or at least reduce the formation of these deposits to a tolerable level it is necessary with these prior art devices to quench to much lower temperatures than is desirable. This, on the other hand, renders the quench medium-when separated from the gaseout reactor efiluenttoo cold to facilitate economical use of the quenched heat.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome the aforementioned disadvantages.

More particularly, it is an object of the present invention to provide for more rapid quenching of reactor eflluents than was heretofore possible, assuring quicker and more uniform heat exchange between the efiiuent and the quenching liquid.

A concomitant object of the invention is to provide for quick and intimate quenching of the reactor efiluent without producing a significant pressure drop of the reaction product in the quenching device.

Still a further object of the invention is to provide a method of quenching with the aforementioned advantages in mind, and which additionally will result in an increased yield of the desired reaction product, such as ethylene obtained by pyrolysis of low molecular weight hydrocarbons.

A still further object of the invention is to provides such a quenching method which will permit quenching of the reactor effiuents at higher temperatures of such an order as to facilitate heat recovery from the quench fluid, without substantial formation of coke or similar deposits.

Yet an additional object of the invention is to provide an apparatus for carrying the novel method into effect.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in a method of quenching hot fluid, such as heated hydrocarbons, which method briefly stated comprises the steps of conveying a stream of hot fluid in a predetemined enclosed path from an upstream end of an inlet region through an expansion region and to an end of the latter downstream of the expansion region. Quench fluid is injected into the stream of hot fluid in the expansion region coaxially and concurrently with the stream, the quench fluid being cooler than the hot fluid and which could, for instance, be constituted by liquid recirculated hydrocarbons if the hot fluid is constituted by heated by drocarbons.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic illustration showing an apparatus according to the present invention;

FIG. 2 is a diagrammatic view similar to FIG. 1, but illustrating a further embodiment of the invention; and

FIG. 3 is a detail view, partly in longitudinal section and on an enlarged scale, of an injection nozzle for use in the apparatus of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly the embodiment of FIG. 1, it will be seen that a reactor of any known construction suitable for the purposes at hand, such as the pyrolysis of hydrocarbons, is provided internally with a reaction zone 1. While most such reactors are tubular coils, other constructions which may be suitable should be understood as being included in the scope of this description. In conventional manner, well known to those skilled in the art, hydrocarbons-which may or may not be of low molecular weightare introduced into the reaction zone 1, for the purpose of producing ethylene by pyrolysis of those hydrocarbons.

The outlet of the reaction zone 1 communicates with a conduit 3 which in turn communicates with a bent conduit portion 4. The latter defines an angle of approximately at least 45 and its downstream end merges with the upstream end of a conduit portion 5 which diverges so as to constitute an expansion zone. The angle of divergence is preferably between approximately 6 and The radius R of the bent conduit portion 4 is advantageously between 2 and 5 times the diameter d of the conduit portion 3. The manner in which the nozzle 8 injects the quenching fluid into the upstream end of the divergent conduit portion 5 is identified by the arrows and the angle of divergence of the conduit section is shown to be between substantially 6 and 30.

The following example will be indicative of operation of the apparatus according to the present invention, utilizing the embodiment shown in FIG. 1.

Reactor efiluent (gas) entering conduit 3:

Flow rate-12350 lbs./hr. Pressure-30 p.s.i.a. Temperature1450 F. Average molecular weightApprox. 25. Inlet velocity356 ft./sec.

Quench oil, injected through nozzle 8:

Flow rate69500 lbs./hr. Temperature35 0 F.

Initial boiling point- 0 F.

Specific gravityApprox. 1.05. Injection velocity-Approx. ft./ sec. Spray angle of nozzleApprox. 30.

Calculated conditions at ditfusor outlet:

Pressure-28.8 p.s.i.a.

Gas Temperature-550 F. Gas Velocity-49 ft./ sec. Quench oil Tcmp.55 0 F. Quench oil velocity-78 ft./sec.

Because of high gas velocity relative to the quench injection velocity, the actual spray angle becomes smaller than the spray angle of the nozzle, which is determined in a stagnating environment.

The above example is not to be considered limiting in any sense. For purposes of the invention, the values of the various factors included in the example may be within the ranges of the following table, wherein for purposes of comparison the values of the example have been juxtaposed with the respective range in two adjacent columns:

TAB LE Example Range Reactor eflluent:

Molecular weight of gaseous fluid 25 18-40 Inlet velocity, it./sec 356 250-600 Inlet pressure, p.s.i.a. 30 20-50 Inlet temperature, F 1, 450 1, 350-1, 650

Flow rate, lbs./hr 12, 350 6, 000-80, 000 Quench oil:

Quench oil injection velocity, it./see 60 80-150 Quench oil temperature, F 350 250-500 Quench oil flow rates, lbs/hr- 60, 500 20, 000-400, 000

Quench oil specific gravity 1.05 0. 9-1. 15

Quench oil initial boiling point, F 550 400-755 Conditions at difiusor outlet:

Pressure at oultelt, p.s.i.a 28. 8 1 0. 5-4

Outlet temperature (gas and oil) F 550 450-600 Outlet velocity (gas) ft./sec. 49 30-100 Outlet velocity (oil) ft./sec 78 30-150 1 P.s.i.a. below inlet pressure.

Coming to the embodiment of FIG. 2, it will be seen that this is somewhat similar to that of FIG. 1.

The outlet of the reaction zone 1 again communicates with conduit means which comprises a plurality of sections as illustrated. Here, the conduit 3 also communicates directly with the reactor outlet and should again be as short as possible. The conduit 3 is provided with or secured to a bent conduit portion 4 defining an angle of approximately 45 as before. However, the downstream end of the portion 4 in turn communicates with a relatively short circuit portion 5' which diverges in a downstream direction, that is in the direction away from the reaction zone 1, and which in turn is also providedin the region of its downstream end-with a bent portion 6 again defining an angle of approximately 45". The angle of divergence of the conduit portion 5, which latter of course again constitutes an expansion region, is preferably between approximately 6 and 30". Further, a terminal conduit 7 is provided communicating with the downstream end of the bent portion 6 and having a constant or at least substantially constant cross-section for conveying the quenched and quenching fluids away.

'In accordance with the present invention the first nozzle 8 in this embodiment communicates with the bent conduit portion 4 in the region of its upstream end, preferably at its juncture with the conduit 3. A pipeline 9 communicates with the noozle 8 and supplies the latter with quenching fluid, such as recycled liquid hydrocarbons which are a conventional byproduct of ethylene production as is well known to those skilled in the art. This quenching fluid is cool with reference to the temperature of the heated hydrocarbons issuing from the outlet of the reaction zone 1. It is injected by the nozzle 8 towards the outlet region of the bent portion 4 in concurrentdirection with the main flow of the heated hydrocarbons. From the manner of this injection it will be evident that the purpose of the bent portion 4 is to facilitate injection of the quneching fluid coaxially and concurrently with the hot gas stream without requiring obstructions in the flow path of the gas stream, thus avoiding flow disturbances and development of turbulence.

In addition, a second nozzle 10 is provided with communicates with the bent conduit portion 6, again in the region of the upstream end of the portion 6 and at the outer side of the curvature. A supply pipe 11 communicates with the nozzle 10 and supplies thereto additional quenching fluid, that is additional recycled liquid hydrocarbons. This additional quenching fluid is injected b ythe nozzle 10 in concurrent direction into the partially quenched heated hydrocarbons.

It will be observed that after having undergone the initial quenching step and introduction of the quenching fluid by the nozzle 8, the mixturewhich is now partially quenched--is allowed to expand further in the di- 'vergent conduit portion before injection of additional quenching fluid by the nozzle takes place.

In accordance with the invention, less than 50% of the total amount of quenching fluid injected by the

nozzles

8 and 10 together, is injected by the nozzle 8, whereas the rest is injected by the nozzle 10. Preferably, -35% of the quenching fluid are injected by nozzle 8 and the remainder required to make up 100% is injected by the nozzle 10. This makes it possible, in other words, to inject the larger part of the quenching fluid into the gas stream in a zone of lower gas velocity in order to reduce the pressure drop even more than with a single injection.

The invention provides for essentially uniform heating of the quenching liquid by the reactor eflluent in the shortest possible time, without substantial parts of the quenching fluid being heated to temperatures higher than the final equilibrium temperature of the mixture consisting of reactor effluent and quenching fluid. This makes it possible to operate the quench system according to the present invention closely up to the temperature at which the quenched components, or the constitutent components of the quenching fluid, would become unstable and decompose.

The injection of quenching fluid through the nozzle 8 takes place in both embodiments in form of a full cone spray with a velocity which is no lower than approximately half of the velocity of the liquid-vapor mixture at the downstream end of the conduit portion 5 or 5'. The width of the spray cone is so selected that the cross-section of the conduit portion 5 or 5 is rather completely covered with quenching fluid spray, but that the walls bounding the conduit portion 5 or 5' are not wetted with the quenching fluid until the gaseous reactor effluent and the quenching fluid injected by the nozzle 8 have approached the same--equilibriumtemperature.

The length and the angle of the conduit portion 5 or 5' are so selected that the droplets of quenching fluidwhich is a liquidand the gaseous reactor eflluent leave the downstream end of the conduit portion 5 or 5' with essentially the same velocity, which may be on the order of substantially 70-100 feet per second. By'having the angle of divergence of the conduit portion 5 or 5' arranged to be between approximately 6 and 30, flow disturbance is avoided. The nozzle 10 is so positioned as to inject the additional quenching fluid before the quenching fluid injected by the nozzle 8 can contact the wall bounding the conduit.

The embodiment in FIG. 3 is illustrative of the construction of a nozzle suitable for the

nozzles

8 or 10 of the preceding embodiments. It will be seen that a nozzle 8 is shown connected by way of example with the wall of the bent conduit portion 4 which is suggested only diagrammatically. Reference numeral 30 identifies a housing having an outlet 31 communicating with an aperture pro, vided in the wall of the conduit portion 4. Reference numeral 32 identifies an elongated spindle which is secured via mating screw threads 39 in a nut or analogous means 40 connected to the rearward open end of the housing 30. Reference numeral 36 identifies screw threads provided in the forward region of the spindle 32 with rather coarse thread cut in opposite direction (left) to the thread 39 (right). The spindle 32 can be turned due to thread 39 in nut 40 and thereby be moved forwardly or rearwardly like a valve stem with respect to the outlet opening 31 in coaxial relationship with the tubular housing 30. Reference numeral 33 identifies the leading portion of spindle 32, and reference numeral 34 identifies a forwardly tapering portion which defines with the wall of the housing 30 surrounding the outlet opening 31 an annular clearance or gap 35 which, it will be evident, increases or decreases in radial width depending upon the extent to which the spindle 32 is moved forwardly or rearwardly. This controls the ejection of fluid from the nozzle 8. Reference numeral 37 identifies a wall portion located rearwardly of an inlet opening 38 to which a suitable nipple or analogous means may be connected for introducing the quenching fluid into the nozzle. Reference numeral 41 is a seal located rearwardly of the wall portion 37 and forwardly of the nut 40 so as to prevent escape of quenching fluid in that direction. The thread 36 imparts to the quenching fluid a rotary motion. Thread 39 causes the spindle 32 to move in outlet 31 in the manner of a drill, dislodging any contaminants which might tend to accumulate and clog the outlet 31.

It will be evident, however, that other nozzle construc tion will offer themselves to those skilled in the art.

It has been found that according to the present invention quick and intimate quenching of the reactor efiluent is obtained, and that polymerization of the reaction product is reduced with a concomitant reduction in the deposit of tars and coke.

The reaction of the quench is improved as a result of combining the quench process with the necessary decelration of the reactor efiluent, the quenching liquid having a lower velocity than the gas entering from the reactor but a velocity which is perferably in the range of the velocity of the gas after the latter is decelerated. It will be evident that the gas, entering with high velocity, first tends to accelerate the quench liquid and that the resulting energy exchange tends to temporarily reduce the pressure of the gas, and to favor temporary partial vaporization of the liquid as well as a temperature decrease of the gas by a Joule Thompson effect. Although these effects are reversed in the lower part of the diffusor, that is the conduit portion 5 or 5', they improve the quench action by the more rapid initial temperature drop.

The presence of the divergent conduit portions 5 and 5' provides for a gradual slow-down of the effluent with minimum friction, thereby assuring that essentially all of the available kinetic energy of the eflluent is converted into potential energy and thus made available for overcoming resistance downstream of the conduit portion 5 or 5'. Because the quench fluid is injected into the efiluent at the velocity which the mixed streamconsisting of the eflluent and the quenching fluid-will have as it leaves the downstream end of the conduit portion 5 or 5, no mechanical energy in the efiiuent is used solely for the purpose of accelerating the quench fluid to the final velocity. Any exchange in such energy which may take place between the inlet and outlet section of the quench zone is recovered by the time the mixture reaches the outlet of the zone, that is the outlet of the conduit portion or 5.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of method and apparatus for segregating the components of secondary cells differing from the types described above.

While the invention has been illustrated and described as embodied in a method and apparatus for quenching of hot lfluids it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed is:

1. A method of quenching hot fluids, comprising the steps of conveying a stream of hot fluid ni an enclosed path from an upstream end through an expansion region and to a drownstream end of said path; and injecting into said stream in concurrent flow therewith in sections up stream and downstream of said expansion region a smaller first and a larger second quantity of quenching fluid, respectively, in the form of full-cone sprays.

2. A method as defined in claim 1, further comprising the step of deflecting the hot fluid in said section through respective angles on the order of 45.

3. A method as defined in claim 1, wherein said first quantity of quenching fluid is less than 50% of the total of said first and second quenching fluids.

4. A method as defined in claim 1, wherein the amount of said first quantity of quenching fluid is between substantially and 35% of the combined total amounts of said first and second quantities.

5. A method as defined in claim 3, wherein said hot fluid is composed of hot gaseous hydrocarbons.

6. A method as defined in claim 5, wherein said liquid is composed of recirculating hydrocarbons.

7. A method as defined in claim 5, and further comprising the preliminary step of subjecting said hydrocarbons to a reaction immediately prior to entry into said upstream end of said path.

8. A method as defined in claim 7, said preliminary step comprising subjecting said hydrocarbons to pyrolysis to thereby produce ethylene.

9. A method of quenching hot gaseous fluids, comprising the steps of conveying a stream of hot gaseous fluid in an enclosed path from an upstream end through an expansion region thereof; and injecting into said hot gaseous fluid in said expansion region in form of a fullcone spray and in concurrent flow with said stream a quenching liquid which is cooler than said hot gaseous fluid.

10. A method as defined in claim 9, wherein said liquid and said gaseous fluid issue from said expansion region with a predetermined outlet velocity, and wherein the step of injecting said quenching liquid comprises injecting the same with a velocity having a minimum value of approximately half of said predetermined velocity.

11. A method as defined in claim 10, wherein the crosssectional area of said path diverges in said expansion region in downstream direction, and wherein the angle of said full-cone spray and the angle of divergence of said path in said expansion region are so selected that the cross-sectional area of said full-cone spray at least substantially approaches that of said expansion region but that said quenching liquid contacts the inner circumference of said path only upon at least approaching equilibrium temperature with said hot gaseous fluid.

12. A method as defined in claim 11, and further comprising the step of injecting additional quenching liquid into said stream of hot gaseous fluid in said expansion region upstream of the area of contact of the first-mentioned quenching liquid with the inner circumference of said path.

13. A method as defined in claim 9, wherein said expansion region has a predetermined angle of divergence and a predetermined length in downstream direction of said path, said predetermined angle and said predetermined length being so selected that said gaseous fluid and injected quenching liquid in droplet form issue from said expansion region with substantially identical velocities.

14. A method as defined in claim 9, wherein said gaseous fluid has an average molecular weight of 18 to 40 and enters said path with an inlet velocity of 250 to 600' ft./sec., at a pressure of 20 to 50 p.s.i.a., an inlet temperature of 1350 F. to 1650 F. and a flow rate of 6000 to 80,000 lbs./hr., said quenching liquid being oil and being injected at a velocity of substantially 30 to ft./sec. at an injection spray angle of substantially 30, a temperature of 250 F. to 500 F. and a flow rate of 20,000 to 400,000 lbs./hr., said oil having a specific gravity of substantially between 0.9 and 1.15 and an initial boiling point of 400 F. to 750 F; and wherein at the downstream end of said expansion region the pressure prevailing is between 0.5 and 4.0 p.s.i.a. below said inlet pressure, the temperature of said gaseous fluid and oil is between 450 F. and 600 F., and the velocity of said gaseous fluid and oil is between 30-100 ft./sec. and between 30-150 ft./sec., respectively.

15. A method as defined in claim 14, wherein said gaseous fluid has an average molecular weight of 25 and enters said path with an inlet velocity of 356 ft./sec., a pressure of 30 p.s.i.a., a temperature of 1450 F. and a flow rate of 12350 lbs./hr., said quenching liquid being oil and being injected at a velocity of substantially 60 ft./sec. at an injection spray angle of substantially 30, a temperature of 350 F. and a flow rate of 69500 lbs./ hr., said oil having a specific gravity of substantially 1.05 and an initial boiling point of 550 F.; and wherein at the downstream end of said expansion region the pressure prevailing is 28.8 p.s.i.a., the temperature of said gaseous fluid and oil is 550 F., and the velocity of said gaseous fluid and oil is 49 ft./sec. and 78 ft./sec., respectively.

16. An apparatus for quenching hot fluids, particularly heated hydrocarbons, comprising first means constituting a source of hot gaseous fluid to be quenched; second means comprising wall means defining an enclosed path and communicating with said first means for receiving a stream of hot gaseous fluid therefrom, said path including a quenching section having a downstream end; said quenching section 'being defined by a. portion of said wall means diverging in the downstream direction; and third means for injecting into said quenching section and in concurrent flow with said stream a quenching liquid in form of a full-cone spray and at a predetermined velocity having a minimum value of approximately half the velocity at which said stream of hot gaseous fluid and the droplets of injected quenching fluid subsequently issue from said downstream end of said quenching section.

17. An apparatus as defined in claim 16, wherein the angle of said full-cone spray, the angle of divergence of said wall portion and the length of said quenching zone are so selected that the cross-sectional area of said fullcone spray is substantially equal to the cross-sectional area of said quenching section at all points of the latter, but that the injected quenching liquid contacts and wets said wall portion only upon said injected quenching liquid at least approachnig equilibrium temperature with said hot gaseous fluid.

18. An apparatus as defined in claim 17, and further comprising additional means for injecting additional quenching liquid into said quenching section upstream of the area of initial contact between the first-mentioned quenching fluid and said wall portion.

9 19. An apparatus as defined in claim 17, wherein the angle of divergence and the length of said quenching section are so selected that said hot gaseous fluid and the injected quenching liquid issue from said downstream end of said quenching section with substantially identical velocities.

969,502 9/1910 Taussig 202-254 3/ 1965 Clark et al. 208-48 1 10 3,243,360 3/1966 Wethly 202-256 2,027,538 1/1936 McIntil'e 202254 1,803,881 5/1931 Ackeren 202-260 5 DELBERT E. GANTZ, Primary Examiner J. M. NELSON, Assistant Examiner 0 US. Cl. X.R.