DE2104478A1 - Method and device for cooling hot media - Google Patents

Description

Dr, Ing. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, patent attorneys, Cologne Attachment file number

on the entry dated January 12, 1971 vA // Named.Nm. The Lummus Company,

1515 Broad Street, Bloomfield, N.J. 07003, UNITED STATES.

Method and device for cooling hot media

The invention relates generally to the cooling of hot Media and especially the cooling of heated hydrocarbons «The invention relates in particular to a method for | Cooling of heated hydrocarbons and a device for carrying out the process »

In the following description, particular reference is made to the cooling of heated hydrocarbons. However, while the invention is particularly good for this purpose is appropriate, it should be noted that the explanation of the invention in terms of cooling heated hydrocarbons is given by way of example only and that the invention is in no way limited thereto. It is known that at Modern chemical processes many chemical reactions are carried out at high temperatures in order to achieve a rapid reaction to achieve speed. The problems to which the invention is directed belong to many such chemical ones Reactions such as the production of ethylene by pyrolysis of hydrocarbons, in particular, but not exclusive of low molecular weight hydrocarbons.

In this ethylene production, as in the other chemical reactions mentioned above, the most important thing is the reaction to bring to a standstill at a predetermined point in time, or at least substantially the rate of reaction

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rapidly to avoid the formation of by-products and residues resulting from secondary reactions result, so that a maximum yield of the desired product is achieved. In the case of the aforementioned, for example Production of ethylene are therefore hydrocarbons with a very high throughput rate in a Reaction zone introduced. The hydrocarbons are quickly brought to and at the reaction temperature held for a period of time that can be a fraction of a second. Under these conditions, ethylene is the ' primary resulting product «

However, it is known that if the reaction products are not cooled immediately, secondary reactions (such as the Polymerization) take place, which results in the production of tars and coke, as well as a decrease in the yield of ethylene. Besides this rather obvious disadvantage, there is the fact that when the secondary reactions are allowed to take place, the generated Tar and the coke clog and block the pipes, valves and other components of the device endeavor, which results in complicated maintenance problems and often the shutdown of the plant.

All of these problems are self-evident from the industry have been recognized and many attempts have been made to overcome them. Despite realizing that the problems overcome and the desired results can be achieved by cooling the reactor effluent by using the same A flow of cold medium is brought into intimate contact with the large number of devices that are used for this purpose have become known still have various disadvantages which make them less than useful. Lots of these known devices in particular do not see the speed and intimacy of mixing the drain with the cooling medium before that are required. The same or different devices use a considerable amount of the cooling equipment Pressure drop, although such known devices cause

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rapid cooling, but only at the expense of a higher pyrolysis pressure, which in turn reduces the yield of the desired product, or at the expense of a lower pressure the downstream side. As a result, more powerful compressors are required, which are accordingly more expensive in their acquisition costs and in their subsequent operation, to introduce the reaction products into the subsequent treatment units.

Another and perhaps the most significant deficiency of the known devices is the formation of coke, polymer or similar deposits when the devices are operated at temperatures which facilitate the recovery of waste heat by generating steam in a cooling device. Among other things, to avoid the formation of these deposits or at least reduce them to a tolerable level, it is necessary with these known devices to cool to much lower temperatures than is desirable. This, on the other hand, makes the cooling medium, when it is separated from the gaseous reactor effluent, kju ka "v" in order to facilitate the economical use of the waste heat.

Accordingly, it is an object of the invention to overcome the aforementioned drawbacks.

One object of the invention is, in particular, for a much faster cooling of the reactor effluent than was previously possible, as well as faster and more uniform Ensure heat exchange between the drain and the cooling liquid.

Another object of the invention is to provide rapid and uniform cooling of the reactor effluent carry without producing a significant pressure drop of the reaction product in the cooling device.

Another object of the invention is taking into ^{account- L} 68/4 109833/1394 -3-

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supply of the aforementioned advantages in the formation of a cooling process which additionally results in an increased yield of the desired reaction product such as ethylene obtained by pyrolysis of low molecular weight hydrocarbons _{or the like}

Yet another object of the invention is to provide such a cooling method which allows the cooling of the Reactor effluent at higher temperatures of such magnitude allows heat to be recovered from the cooling medium is facilitated without substantial formation of coke or similar deposits.

An additional object of the invention is to provide an apparatus for carrying out the new method.

The invention therefore relates to a method for cooling a hot medium, such as, for example, heated hydrocarbons. Briefly summarized, the process comprises the following steps: promoting a flow of the hot medium into a predetermined enclosed path from the upstream end of an inlet area through an expansion area and to one end of the latter, which is downstream of the expansion area »Into the flow of the hot medium In the expansion area, the cooling medium is injected coaxially with and simultaneously with the flow. The cooling medium is cooler than the hot medium and could, for example, consist of liquid cooling hydrogen put into circulation again, when the hot medium consists of heated hydrocarbons.

The invention thus relates to a method and a device for cooling hot gases that are used in the treatment of hydrocarbons can be obtained. A stream of hot gaseous hydrocarbons emerges from a reactor and becomes promoted in one line. The latter is in the immediate vicinity of the outlet which connects the reactor with the pipe

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provided with a curvature formed by a long radius of at least about 45 ° in order to allow the injection of the Cooling liquid simultaneously and coaxially to facilitate the flow of hot gaseous hydrocarbons without obstruction the flow path of the hot gaseous hydrocarbons to avoid any disturbance of the flow of the hot gaseous Avoid hydrocarbons passing through the pipe. Downstream of this bend the conduit diverges to form a diffuser. The bend is at least connected to a liquid-injecting nozzle, which recirculates the cooling liquid, such as, for example set hydrocarbons, is injected into the outlet end of the bend. "

Some exemplary embodiments of the invention are described below with reference to the drawings, in FIG which shows;

Fig. 1 is a schematic representation of a device according to the invention,

FIG. 2 shows a nematic representation similar to FIG further embodiment of the invention illustrated, and

Fig. 3 on a larger scale and in a vertical longitudinal section, an injection nozzle, which in the device according to the Figures 1 and 2 can be used.

Referring to Fig. 1, there is a reactor of known construction suitable for the purposes in question, such as, for example the pyrolysis of hydrocarbons, provided with a reaction zone 1 inside. While most reactors of this type consist of pipe coils, other corresponding constructions should also be within the scope of this description fall. In the usual manner known to the person skilled in the art, hydrocarbons, which may have a low molecular weight, are

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nen or not, introduced into reaction zone 1 to produce ethylene by pyrolysis of these hydrocarbons.

The outlet of the reaction zone 1 is connected to a line 3 which, on its side, is connected to a curved line part 4. The latter defines an angle of at least approximately 45 ° and its downstream end is connected to the upstream end of a conduit part 5 which diverges to form an expansion zone. The divergence angle is preferably between 6 ° and 30 ° _o

The radius R of the curved line part 4 is advantageous two to five times the diameter d of the pipe part 3. The way in which the nozzle 8 the cooling liquid injected into the upstream end of the diverging conduit part 5 is indicated by the arrows.

The following example shows the mode of operation of the device according to the invention when using the one shown in FIG Execution form.

Reactor outflow (gas) entering line 3:

Flow velocity 5ο594 kg / h pressure 2.10 kg / cm ² temperature 788 ° C Average molecular weight about 25 Entry speed 106.8 m / s The nozzle 8 injected cooling oil: Flow velocity 31,483 kg / h temperature 177 ° C Initial boiling point 288O C specific weight about 1.05 Injection speed about 18 m / s Spray angle of the nozzle about 30 °

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Calculated conditions at the outlet of the diffuser:

Pressure 2.016 kgf / cm ²

Gas temperature 288 ° C

Gas speed 14.7 m / s

Cooling oil temperature 288 ° C

Cooling oil speed 23.4 m / s

Because of the high gas velocity relative to the injection velocity of the cooling oil, the actual spray angle is smaller than the spray angle of the nozzle, which is in a stagnant Environment is determined.

The above example is not intended to be limiting in any way. For the purposes of the invention, those given in the example can be used Values of the various factors are within the ranges of the table below, with the Values from the example for the relevant area have been placed side by side in two adjacent columns.

TABLE m / s L E example area Reactor drain kp / cm Molecular weight of the gaseous ° C 25th 18-40 Medium kg / h 106.8 75-180 Entry speed 2.10 1.4-3.5 Inlet pressure 788 732-899 Inlet temperature 5,594 2.718-36240 Flow velocity

Cooling oil

Injection speed temperature

Flow velocity Specific gravity Initial boiling point

m / s 18th 9-45 ° C 177 121-260 kg / h 31 ο483 9060-181200 1.05 . 0.9-1.15 ° C 288 204-399

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kp / cm example 2104478 t ° C 2.016 area Diffuser outlet conditions m / s 288 0.035-0.28 * Pressure at outlet m / s 14.7 232-316 Outlet temperature
(Gas and oil) 23.4 11.4-30 Exit speed
(Gas) 9-45 Exit speed
(Oil)

* kp / cm below the inlet pressure

The embodiment shown in FIG. 2 is similar to that according to FIG. 1.

The outlet of the reaction zone 1 is again connected to a line which consists of several parts. Here, too, the line 3 is connected directly to the reactor outlet and should be as short as possible. The line 3 is connected to a curved line part 4 which delimits an angle of approximately 45 °. The downstream end of the conduit part 4 is; in turn connected to a relatively short line part 5 ¹ , which diverges in the downstream direction, i.e. in the direction facing away from the reaction zone 1, and which in turn is also connected in the region of the downstream end to a curved line part 6, which again has one Limited to an angle of approximately 45 °. The divergence angle of the line part 5 ¹ , which forms an expansion zone, is preferably between 6 ° and 30 °. Furthermore, a last line part 7 is provided which is connected to the downstream end of the curved line part 6 and which has a constant or substantially constant cross section in order to discharge the cooled medium and the cooling liquid.

According to the invention, in this embodiment the first nozzle 8 with the curved line part 4 is in the region of the upstream lying end of the same connected, preferably at the connection with the line 3. With the nozzle 8 is a pipe

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line 9 is connected and supplies the same to the cooling liquid, such as, for example, liquid hydrocarbons put into circulation again, which are a common by-product of ethylene production, as is known to those skilled in the art. This coolant is cool relative to the temperature of the heated hydrocarbons, which emerge from the outlet of reaction zone 1. The cooling liquid is fed through the nozzle 8 into the outlet area of the curved pipe part 4 is injected in the same direction with the main flow of the heated hydrocarbons. It follows from the nature of this injection that the purpose of the curved pipe part 4 is to perform the injection to facilitate the cooling liquid coaxially and at the same time with the hot gas flow, without obstacles in path I. the gas flow are required, so that flow disturbances and color formation can be avoided.

In addition, a second nozzle 10 is provided, which is connected to the curved line part 6, also in the Area of the upstream end thereof and on the outside of the curve. With the nozzle 10 is a pipe 11 connected and supplies the same additional cooling liquid, i.e. liquid hydrocarbons put into circulation again, This additional cooling liquid is heated by the nozzle 10 in the same direction in the partially cooled Injected hydrocarbons. |

After the initial cooling process and the introduction of the cooling liquid through the nozzle 8, the now partially cooled mixture can expand further in the diverging line part 5, before the additional cooling liquid is injected through the nozzle 10.

According to the invention, less than 50 % of the total amount of the cooling liquid that is injected through the nozzles 8 and 10 together is injected through the nozzle 8, while the remainder is injected through the nozzle 10. Preferably, 15 to 35 % of the cooling liquid is injected through the nozzle 8

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and the remainder missing to 100% is injected through the nozzle 10. In other words, this enables the greater part of the cooling liquid to enter the gas flow in a zone inject at low gas velocity to reduce the pressure drop more than with a single injection.

The invention provides for a substantially uniform heating of the cooling liquid through the reactor drain in the shortest possible time Time before, without substantial parts of the cooling liquid being heated to temperatures that are higher than the final equilibrium temperature of the mixture consisting of the reactor effluent and the cooling liquid. This enables to operate the cooling system according to the invention up to that temperature at which the cooled components or the proportionate components of the coolant become unstable and decompose.

The injection of the cooling liquid through the nozzle 8 takes place in both embodiments in the form of a complete cone at a speed which is not less than approximately half the speed of the liquid-vapor mixture at the downstream end of the line part 5 or 5 ¹ · the width of the spray cone is chosen so that the cross-section of the line part 5 or 5 ^{f is} almost completely filled by the cooling liquid, but that the walls delimiting the line part 5 or 5 * are only wetted by the cooling liquid until the gaseous reactor effluent and that injected through the nozzle 8 Coolant have reached the same equilibrium temperature.

The length and the angle of the line part 5 or 5 'are chosen so that the droplets of the cooling medium, which is a liquid, and the gaseous reactor effluent ^{leave the downstream end of the line part 5 or 5 1} at substantially the same speed, which is about 21 to 30 m / s. When the divergence angle of the pipe part

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5 or 5 ^! is between 6 ° and 30 °, a flow disturbance is avoided. The nozzle 10 is arranged so that it injects the additional cooling liquid before the cooling liquid injected through the nozzle 8 can contact the wall delimiting the line.

Pig. Figure 3 illustrates the construction of a nozzle suitable for the nozzle 8 or 10 of the previous embodiments is. The nozzle 8 is connected, for example, to the wall of the curved line part 4, which is only shown schematically is. A housing 30 has an outlet 31 which is in communication with an opening in the wall of the Line part 4 is provided. An elongated spindle 32 | is through a corresponding screw thread 39 in a nut 40 or the like attached, which is connected to the rear open end of the housing 30. At the front end of the Spindle 32 is a screw thread 36 as a left-hand thread in opposite direction to the screw thread 39 designed as a right-hand thread is provided. The spindle 32 can by means of of the screw thread 39 are rotated in the nut 40 and thus like a valve spindle relative to the outlet opening 31 can be moved back and forth coaxially with the tubular housing 30. The front end of the spindle 32 is 33 be-r and with a forward beveled part of the spindle is designated with which the outlet opening 31 is a Benden wall of the housing 30 delimits an annular gap 35, the radial width of which increases or decreases in the The extent to which the spindle 32 is moved forwards or backwards. This will cause the liquid to flow out of the nozzle 8 regulated. A wall part 37 is arranged behind an inlet opening 38 with which a corresponding nipple or the like can be connected to introduce the cooling liquid into the nozzle. A seal 41 is behind the wall part 37 and arranged in front of the nut 40 in order to prevent the escape of the cooling liquid in this direction. The screw thread 36 gives the coolant a rotary motion. The screw thread 39 has the effect that the spindle 32 is in the outlet opening

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tion 31 moved in the manner of a drill to remove impurities which collect in the outlet port 31 and seek to clog it.

Of course, however, another nozzle construction known to the person skilled in the art can also be used,

It has been found that, according to the invention, rapid and uniform cooling of the reactor effluent is achieved and that the polymerization of the reaction product is reduced with a simultaneous reduction in the deposition of tea. ren and coke.

The cooling reaction is improved as a result of the combination of the cooling process with the required slowing down of the reactor discharge, wherein the cooling liquid has a lower velocity than the gas entering from the reactor, but a speed which is preferably in the range of the speed of the gas after it decelerates has been. The gas entering at high speed first tries to accelerate the cooling liquid, and the resulting energy exchange seeks temporarily, the To reduce the pressure of the gas and to favor a temporary partial evaporation of the liquid, as well as a decrease in temperature of the gas by a Joule-Thompson effect. Although these effects are reversed in the lower part of the diffuser be, that is, in the line part 5 or 5 ', they improve the cooling effect due to the more rapid initial temperature drop.

The presence of the diverging conduit part 5 or 5 ¹ causes a gradual slowing down of the drain with minimal friction, thereby ensuring that essentially all of the available kinetic energy of the drain is converted into potential energy and therefore to overcome the resistance downstream of the conduit part 5 or 5 ¹ is available. Since the coolant in the drain with the

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Velocity is injected, which has the mixed flow consisting of the drain and the cooling liquid on leaving the downstream end of the line part 5 or 5 ^f , no mechanical energy of the drain is used solely for the purpose of accelerating the cooling liquid to the final speed, Any exchange of energy which takes place between the inlet and the outlet of the cooling zone is recovered by the time the mixture reaches the outlet of the zone, that is to say at the outlet of the duct part 5 or 5 ".

Each of the above-described elements, or two or more of them * can find useful application in order to isolate the components of the secondary cells which are different from the types described above in other types of the method "and the device.

The invention is not limited to the illustrated and described exemplary embodiments, the various Can experience changes without departing from the scope of the invention,

Patent claims:

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Claims (21)

Dr. ing, E. BERKENFELD · D i ρ! .- 1 ng. H. B ERKE N FE LD, patent attorneys, Cologne Attachment file number on the submission of January 12, 1971 Wi. Name d. Ann ,. The Luiiimus Company Claims Process for cooling hot media, characterized in that, that a flow consisting of the hot medium is passed on a predetermined path through an expansion zone and a smaller first and a larger second quantity both upstream and downstream of this area a cooling medium is injected. 2) Method according to claim 1, characterized in that both the first and the second amount of coolant in the form of conical spray jets and in the direction of the to be cooled Medium are injected into this. 3) Method according to claim 1, characterized in that the flow of the hot medium is deflected by predetermined angles at the i locations where the cooling media are injected. 4) Method according to claim 3, characterized in that the angles are on the order of 45 °. 5) Method according to claim 1, characterized in that the size of the first amount of coolant is the same as that of the second amount of coolant approximates. 6) Method according to claim 1, characterized in that the first amount of coolant is between about 15 and 35 % of the total amount of coolant. 7) Method according to claim 1 to 6, characterized in that the hot medium consists of hydrocarbon gases. L 68/4 109833/1394 -l- 8) Method according to claim 1 to 6, characterized in that the coolant consists of recycled hydrocarbons. 9) Method according to claim 7 »characterized in that the Hydrocarbon gases are subjected to a chemical reaction before they enter the expanding zone. 10) Method according to claim 9, characterized in that the Hydrocarbon gases for the production of ethylene by pyrolysis get abandoned. 11) Method according to claim 1 to lo, characterized in that that the liquid and the gaseous components with a f exit from the expansion zone at a certain exit speed and the cooling liquid is injected into this zone at a rate which is at most slightly less than half this predetermined speed lies. 12) Method according to claim 1 to 11, characterized in that the cross section of the flow path in the Expansionsζone increases in the direction of flow, and that the angle of the conical Spray jet and the deflection coil of the flow path are selected in the expansion zone so that the cross-sectional area of the conical spray jet is the cross-sectional area of the Expansion area at least substantially approximates, but that j the cooling liquid only then covers the inner circumference of the flow path touches when it is an equilibrium temperature with the hot Medium reached. 13) Method according to claim 1 to 12, characterized in that the expansion area has a certain divergence angle and a certain length in the downstream direction from the predetermined path, and that the predetermined angle and length are selected so that the hot gaseous Medium and the injected cooling liquid in droplet form with practically identical speeds from the expansion zone step out. L 68/4 109833/1 39A -2- 14) Method according spoke 1 to 13, characterized in that the gaseous medium has an average molecular weight of 18 to 4o and with an entry speed of 75 to 18o m / sec at a pressure of 1.41 to 3.52 kg / cm absolute, with β inlet temperatures between 732 and 899 ° C and with an amount of 27oo to 36,000 kg / h occurs, the cooling liquid is oil and with a. Speed of practically 9 to 45 m / sec and with a spray angle of practically 30 °, with a temperature of 121 to 260 ⁰ and in an amount of 9,000 to 18,000 kg / h, the oil has a specific gravity of essentially 0, 9 to 1.15 and a boiling point of 2o4 to 4oo C, the pressure at the downstream end of the expansion zone is 0.035 to 0.28 kg / cm below the inlet pressure, the temperature of the gaseous medium and the oil is between 232 and 316 °, and the speed of the gaseous medium and the oil is between 9 and 30 and between 9 and 45 m / sec, respectively. 15) Method according to claim 14, characterized in that the (8 gaseous medium has an average molecular weight of 25 and enters the flow path at an entry velocity of Io7 m / sec Pressure of 2.11 kg / cm, at a temperature of 788 ° C and in an amount of 5 · 55ο kg / h, the KiIi coolant is oil and with a speed of essentially 18 m / sec is injected at a spray angle of practically 30 °, at a Temperature of 177 ° C and with an amount of 30,000 kg / h, the oil has a specific weight of about I, o5 and a initial boiling point of 288 ° C, that the pressure at the flow downstream end of the expansion zone t is 2.03 kg / cm, the temperature of the gaseous medium and the oil is 288 ° C. and the speed of the gaseous medium and the oil is 15 and 23 m / sec, respectively. 16) Device for performing the method according to claim 1 to 15, characterized by a Line (5) for receiving the hot gases to be cooled, and through nozzles (8 and Io) for injecting coolants into a first 109833/1394
L 68/4 -3- and into a second zone, the one being injected into the first zone The amount of coolant is at most equal to the amount of coolant injected into the second zone. 17) Apparatus according to claim 16, characterized in that the line has a cooling zone with an H having downstream end, the nozzles (8 and Io) the coolant Inject into the cooling zone in the same direction as the gases to be cooled, namely in the form of a conical spray jet and at a speed that is not significantly less than half the speed at which they are called Gases and the droplets of the injected cooling liquid exit the cooling zone at the downstream end. 18) Apparatus according to claim 16 and 17, characterized in that the line (5) in a downstream Has direction diverging wall section and this encloses the cooling zone. 19) Device according to claim 16 to 18, characterized in that the angle of the conical spray jet the divergence angle of the wall section of the line (5) and the length of the cooling zone are chosen so that the cross-sectional area of the conical spray jet at all points of the cooling zone is essentially the same as the cross section of this cooling zone, but that the injected cooling liquid covers the wall section of the Line (5) is only touched and wetted when the injected coolant is at equilibrium temperature with the at least approximates hot gases. 20) device according to claim 16 to 19, characterized in that additional devices for injection of additional cooling liquid into the cooling zone upstream from the area of original contact between the first coolant and the wall portion are provided. 109833/1394 21) Device according to claim 16 to 2o, characterized in that the divergence angle and the length of the cooling zone are chosen so that the hot gases and the injected cooling liquid emerge from the cooling zone at essentially the same speeds. 109833/1394
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