Title:
DEVICES FOR COOLING GASES WHICH FORM A CORROSIVE CONDENSATION PRODUCT UPON COOLING
Kind Code:
A1


Abstract:
A device for cooling hot gases (quencher) with the formation of a corrosive condensation product, which device has a pressure-resistant container and at least one corrosion-resistant internal gas guide pipe, and to a method of cooling gases that form corrosive condensation products, which method uses the mentioned device.



Inventors:
Diekmann, Helmut (Burscheid, DE)
Gottschalk, Lutz (Dusseldorf, DE)
Hallenberger, Kaspar (Leverkusen, DE)
Ruffert, Gerhard (Leverkusen, DE)
Werner, Knud (Krefeld, DE)
Application Number:
11/752383
Publication Date:
12/20/2007
Filing Date:
05/23/2007
Assignee:
Bayer Material Science AG (Leverkusen, DE)
Primary Class:
Other Classes:
165/DIG.204
International Classes:
F28B9/10
View Patent Images:
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Primary Examiner:
FLANIGAN, ALLEN J
Attorney, Agent or Firm:
POLSINELLI PC (HOUSTON, TX, US)
Claims:
What is claimed is:

1. A device for cooling a hot gas, the device comprising a pressure-resistant container having an inner surface and a corrosion-resistant gas guide pipe having a first and a second end, the gas guide pipe disposed in the container such that contact between at least a majority of the gas and the inner surface is avoided as the gas moves from the first end through the guide pipe to the second end.

2. The device according to claim 1, wherein the pressure-resistant container comprises a material selected from the group consisting of steel alloys, tantalum and alloys thereof.

3. The device according to claim 2, wherein the inner surface is at least partly lined with a material selected from the group consisting of plastics and metals.

4. The device according to claim, wherein the corrosion-resistant gas guide pipe comprises a material selected from the group consisting of graphite, ceramics, plastics, and combinations thereof.

5. The device according to claim 1, wherein the corrosion-resistant gas guide pipe is comprised of a material that is not pressure-resistant.

6. The device according to claim 1, wherein the container further comprises a pressure-resistant gas inlet nozzle.

7. The device according to claim 6, wherein the gas inlet nozzle is insulated, heated, or insulated and heated.

8. The device according to claim 6, further comprising a protective gas contained in an area within the container proximate to the inlet nozzle and the inner surface.

9. The device according to claim 1, further comprising a cooling medium disposed within the container and surrounding at least a portion of the gas guide pipe.

10. The device according to claim 9, wherein at least part of the inner surface is contacted by the cooling medium.

11. The device according to claim 9, wherein the inner surface and the gas guide pipe are separated by the cooling medium.

12. Device according to claim 1, further comprising a spray nozzle disposed in an upper portion of the gas guide pipe.

13. A method of cooling hot gases, the method comprising: (a) providing a device according to claim 1; (b) introducing a hot gas into the container; and (c) contacting the hot gas with a cooling medium in the gas guide pipe.

14. The method according to claim 13, wherein the hot gas is contacted with the cooling medium at a pressure of from −1 to 1000 bar.

15. The method according to claim 13, wherein the hot gas has an entry temperature of 100 to 2000° C.

16. The method according to claim 13, wherein the hot gas and the cooling medium are passed through the gas guide pipe in a concurrent manner.

17. The method according to claim 13, wherein the hot gas and the cooling medium are passed through the gas guide pipe in a counter-current manner.

Description:

BACKGROUND OF THE INVENTION

Many chemical processes that are carried out under pressure comprise a step in which hot gases are cooled rapidly with partial or complete condensation thereof, and the condensation product that forms is often extremely corrosive. Such a step of rapid cooling is generally known as “quenching” (and devices, such as those according to the invention, are therefore also referred to as “quenchers”).

In quenching, the hot gas is generally brought into contact with a comparatively large amount of a cooling medium, which can include the actual condensation product, and the hot gas thereby condenses partially or completely. The resulting condensation products are in many cases highly corrosive.

Contact between the still hot, dry gas and the materials of the quencher does not generally constitute a problem. However, corrosion problems can occur where hot, condensed, moist phase comes into contact with the materials of the quencher. In such regions, temperatures in particular above about 110° C. are to be avoided, otherwise corrosion can occur. In the case of processes that are carried out only under low pressures, the problem can generally be solved by constructing the quencher from a corrosion-resistant material, such as, for example, ceramics, plastics material or graphite. Quenching devices constructed entirely of corrosion-resistant materials are known. For example, quenchers, columns and other process equipment manufactured completely of graphite are available from the SGL Carbon Group, Wiesbaden, Germany. Such equipment is described in a number of publicly available brochures which can be accessed at http://www.sglcarbon.com/. Such quenchers constructed entirely of graphite are usable only at low excess pressures. If quenching at higher pressures is required, however, a material suitable for withstanding high pressures is needed.

Many pressure-resistant materials, such as, for example, alloyed steels or other high strength metal materials, are in some cases not corrosion-resistant in the long term. Additionally, some pressure-resistant materials which may exhibit limited corrosion-resistance can be so expensive that their use cannot be justified economically.

A quenching apparatus suitable for high-pressure applications which does not suffer from the corrosive action of condensed hot gases, and which can be constructed and used economically would be desirable.

SUMMARY OF THE INVENTION

One object of the present invention includes providing an economical device for cooling hot, pressurised gases (i.e., a quencher), which gases condense partially or completely within the device and form a corrosive condensation product, which device does not suffer from corrosion problems to the same degree as prior art devices. This object can be achieved by the provision of a device for cooling hot gases that has a pressure-resistant container and at least one corrosion-resistant internal gas guide pipe.

The present invention relates, generally, to devices for cooling hot gases with the formation of a corrosive condensation product, which devices include a pressure-resistant container and at least one corrosion-resistant internal gas guide pipe, and to methods of cooling gases that form corrosive condensation products, which methods use a device according to the device embodiments of the invention. A combination of a pressure-resistant container and a corrosion-resistant, internal gas guide pipe provides significant protection to the inner surface of the container, which is pressure-resistant but not necessarily adequately corrosion-resistant (at least not in the long term), from the action of the condensed phase at elevated temperature and accordingly reduces the corrosive action of the condensed phase. As a result, it is possible to operate the quencher under pressure and employ inexpensive pressure-resistant materials, such as conventional steel alloys employed in boiler construction.

The present invention includes devices for cooling hot gases (a quencher), which devices comprise a pressure-resistant wall and at least one corrosion-resistant, internal gas guide pipe.

One embodiment of the present invention includes a device for cooling a hot gas, the device comprising a pressure-resistant container having an inner surface and a corrosion-resistant gas guide pipe having a first and a second end, the gas guide pipe disposed in the container such that contact between at least a majority of the gas and the inner surface is avoided as the gas moves from the first end through the guide pipe to the second end.

Another embodiment of the present invention includes a method of cooling hot gases, the method comprising:

(a) providing a device having a pressure-resistant container having an inner surface and a corrosion-resistant gas guide pipe having a first and a second end, the gas guide pipe disposed in the container such that contact between at least a majority of the gas and the inner surface is avoided as the gas moves from the first end through the guide pipe to the second end,

(b) introducing a hot gas into the container; and

(c) contacting the hot gas with a cooling medium in the gas guide pipe.

A “hot gas” within the scope of the invention refers, in general, to gases which are advantageously cooled to a lower temperature before further handling, and in particular, to gases having a temperature of approximately 100 to 2000° C., preferably those having a temperature of 110 to 1000° C. Such gases can include, for example, waste gases and flue gases from combustion processes of any kind, the condensation of which with water forms highly corrosive liquids. They can also be hot process gases of chemical synthesis processes, such as, for example, the process gas of a Deacon process (catalysed oxidation of HCl with oxygen to form chlorine and water), etc.

With the quencher according to one embodiment of the invention it is possible to cool the mentioned hot gases to, for example, below 100° C. (temperature at the gas outlet of the quencher), depending on the inlet temperature.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the Figs.:

FIG. 1 is a schematic representation of a device in accordance with one embodiment of the invention.

FIG. 2 is a magnified view of a portion of the device of FIG. 1 in a preferred embodiment of the invention; and

FIG. 3 is a schematic representation of a device in accordance with yet another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the singular terms “a” and “the” are synonymous and used interchangeably with “one or more.” Accordingly, for example, reference to “a base” herein or in the appended claims can refer to a single base or more than one base. Additionally, all numerical values, unless otherwise specifically noted, are understood to be modified by the word “about.”

Devices according to the invention include a pressure-resistant container. Pressure-resistant within the scope of the invention refers in particular to pressure-resistance (i.e., capacity to withstand) above an excess pressure of 0.5 bar, preferably above 6 bar, more preferably above 10 bar to a pressure of about 1000 bar. The pressure-resistant container of the device is preferably made of a material selected from the group of the conventional steel alloys employed in boiler and apparatus construction, and/or from materials that are known to be alloyable with chromium, nickel, molybdenum, as well as from materials such as tantalum and alloys thereof, whose resistance can be increased further by combination with noble metals such as platinum and/or palladium. These pressure-resistant materials can also be lined with materials selected from plastics and/or metals, such as, in particular, fluorine-containing polymers, such as PFA, PTFE, PVDF, HALAR types, etc., and/or with metals such as tantalum.

In various particularly preferred embodiments of devices according to the invention, the pressure-resistant wall of the device can consist of a material selected from the group comprising steel, steel alloys, in particular with chromium, nickel or molybdenum, and tantalum and tantalum alloys, wherein the materials are optionally lined with plastic or other metallic materials or are at least partially coated.

Devices according to the invention also include a corrosion-resistant gas guide pipe disposed in the container. The gas guide pipe(s) serves to receive the hot gas, which can be passed into the quencher from a gas inlet nozzle which is likewise pressure-resistant. The hot gas then undergoes cooling while it passes through the gas guide pipe(s). As a result of the hot gas being cooled inside the gas guide pipe, contact, in particular, between hot condensed phase and the pressure-resistant but generally not corrosion-resistant inner surface of the container is largely avoided. A gas guide pipe(s) in the devices according to the various embodiments of the present invention is generally arranged substantially vertically within the pressure-resistant container.

Corrosion-resistant internal gas guide pipes suitable for use in the present invention are preferably made of a material selected from the group consisting of: graphite and modifications thereof, ceramics such as silicon carbide, silicon nitride, quartz glass, plastics such as fluorine-containing polymers, such as tetrafluoroperfluoroalkoxy vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylenechlorotrifluoroethylene (ECTFE), Halar types, etc.

The corrosion-resistant internal gas guide pipes are generally made of a material that is not pressure-resistant, that is to say does not withstand in particular excess pressures above 0.5 bar or especially above about 6 bar.

The device according to the invention allows inexpensive materials to be combined to form a pressure-resistant, corrosion-resistant device.

A device according to one embodiment of the invention includes a gas inlet nozzle which is likewise pressure-resistant. The gas inlet nozzle in such an embodiment must be pressure-resistant, but does not have to be made of a particularly corrosion-resistant material, because the incoming pressurized, hot, dry gas, which has not yet condensed, is generally not corrosive. Corrosiveness occurs when condensed, in particular moist, aqueous phase comes into contact at elevated temperatures with metal materials which are susceptible to corrosion. If required or preferred, a gas inlet nozzle can be heated and/or insulated in order to reduce condensation of the incoming gas in that region. In various embodiments which employ a concurrent flow of hot gas and cooling medium, the gas inlet nozzle in the device can be advantageously located above the corrosion-resistant internal gas guide pipe(s) and not in contact with the circulating cooling medium, in order to minimize corrosion of the gas inlet nozzle.

In various particularly preferred embodiments of devices according to the invention, the gas inlet pipe is airtight and thermally insulated and/or heatable.

Devices according to various preferred embodiments of the invention preferably further include one or more design features disposed within the container in regions where condensed phase is exposed to elevated temperatures, such as in the proximity of the hot gas inlet, such features including a barrier or impediment which reduces or prevents contact between the pressure-resistant inner surface and condensed phase at elevated temperatures, in particular temperatures above about 110° C. These are generally the regions of the device in which relatively high temperatures, such as above 110° C., occur in a moist environment, as is the case, for example, in FIG. 3, in the region proximate to, and in particular between, the gas inlet nozzle 3 and the pressure-resistant inner surface of the container wall 5.

In a preferred device according to one embodiment of the invention, a design feature comprising a barrier to reduce or prevent contact between the parts of the device that are susceptible to corrosion, in particular the pressure-resistant inner surface, and condensed phase at elevated temperatures, in particular above 110° C., includes a feed pipe for providing a protective gas, (e.g., a seal gas, or inert gas) to a region between the pressure-resistant inner surface and a portion of the gas inlet nozzle on the inside of the container. The protective gas helps to prevent the combination of hot incoming gas and condensed phase ftom coming into contact with the region that is particularly susceptible to corrosion.

In various preferred embodiments of the present invention, devices according to the invention can comprise at least a gas inlet, a pressure-resistant container comprising the pressure resistant wall, a contact zone, a sump region and a head region for receiving a condensate, an outlet for the cooled gas, a recirculating loop, which conveys condensate from the sump region via a heat exchanger into the head region, wherein the contact zone consists of one or more contact pipes in which condensate is brought into contact with the hot gas from the corrosion-resistant internal gas guide pipe.

In additional preferred embodiments of the devices according to the invention, a gas inlet can be arranged in the sump region and a gas outlet in the head region of the container, so that the gas in the contact pipe is contacted counter-currently with the condensate in the contact pipe.

An alternative device is also preferred in which the gas inlet is arranged in the head region and the gas outlet in the sump region of the container, so that the gas is contacted co-currently with the condensate in the contact pipe.

In various preferred embodiments of devices according to the invention, the sump region and/or the head region of the container can have an additional corrosion-resistant wall or coating at least in the sections contacted by the gas.

In various preferred embodiments of devices according to the invention, an intermediate space between the pressure-resistant wall and the corrosion-resistant wall can be pressurized with a protective gas, and in particular with an inert gas.

In various preferred embodiments of devices according to the invention, during operation, the gas guide pipes are surrounded externally by cooled condensate which flows into the gas guide pipes at the upper end of the gas guide pipes. In various preferred embodiments of devices according to the invention, during operation, the pressure-resistant wall is at least partially in contact with the condensate. In various preferred embodiments of devices according to the invention, during operation, condensate is present between the pressure-resistant wall and the gas guide pipes.

In various preferred embodiments of devices according to the invention, nozzles are arranged in the upper section of the gas guide pipes for injecting and in particular atomizing cooled condensate, and in particular in that the gas to be cooled is conveyed co-currently with the condensate.

One preferred embodiment for a quencher according to the invention operated concurrently, which includes the provision of a barrier comprising a seal gas, is shown in FIG. 3, and is described further below. As can also be seen in FIG. 3, a flow-guiding device, such as the inner cone 7, can additionally be provided for preventing hot gas from coming into contact with the inner surface in the region of the cooling medium.

A further preferred embodiment of a quencher according to the invention operated counter-currently is shown in FIG. 1.

A preferred protective gas for use in devices according to the various embodiments of the present invention can be, for example, an inert gas, such as nitrogen, or a noble gas. In a process gas of a Deacon process, it can preferably be oxygen, which is already present in large amounts in that process gas.

In a preferred device according to an embodiment of the invention, the corrosion-resistant gas guide pipes can be surrounded at least partially by a cooling medium. The cooling medium can preferably enter the gas guide pipes at an upper part of the gas guide pipes where the pipes are preferably substantially vertical. The cooling medium is removed at the lower end of the gas guide pipes and, after cooling, is circulated in or fed back into the device.

Devices according to the invention are generally constructed so that at least part, generally a major part, of the pressure-resistant inner surface is in contact with the circulating cooling medium. As a result, corrosion of the pressure-resistant inner surface, which is generally not or only slightly corrosion-resistant, in that region is effectively prevented, because the elevated temperatures required for corrosion are generally not reached in those regions in contact with the cooling medium.

Devices according to various embodiments of the invention are preferably constructed so that there is circulating cooling medium between a majority of the pressure-resistant inner surface and the gas guide pipes, the circulating cooling medium entering the gas guide pipes at their upper end and being collected at the bottom and recirculated.

In devices and methods according to various embodiments of the invention, a cooling medium comprises a liquid, preferably water or an aqueous acid, such as dilute hydrochloric acid. Other process-specific washing agents, such as, for example, alcohols or aqueous amine solutions, can also be used.

In a device according to one embodiment of the invention as shown, for example, in FIG. 3, the incoming hot gas can be guided concurrently with the cooling liquid. In such a concurrently operated device according to the invention, the device can additionally have, preferably in an upper part of the gas guide pipe(s), one or more nozzles for spraying in the cooling liquid.

In a further embodiment of the device, as is shown, for example, in FIG. 1, the incoming hot gas can be guided counter-currently to the cooling liquid.

Devices according to the invention are suitable, generally, for cooling hot gases having a temperature of 100 to 2000° C., preferably of 110 to 1000° C. (measured at the gas inlet nozzle). A hot gas to be cooled can preferably be a product gas from the catalyzed gas phase oxidation of HCl and oxygen and can preferably contain HCl and water.

Devices according to the invention are generally constructed so that they are suitable for operation at excess pressures of 0.5 to 1000 bar, preferably at 6 to 1000 bar.

The invention relates further to methods of cooling hot gases which can use devices according to the invention. Such methods can preferably be carried out at an excess pressure of 6 to 1000 bar. Furthermore, the temperature of the incoming gas is preferably 110 to 1000° C.

Thus, the present invention includes processes for cooling hot gases, in particular of a temperature in the range from 1000 to 2000° C., using a device according to the invention, wherein hot gas is conducted through the internal gas guide pipe(s) of the device co-currently or co-currently and is cooled by contact with the condensate. A process which is characterized in that the pressure of the gas/liquid contact zone is up to 1000 bars, is preferred. A process in which the gas to be cooled contains hydrogen chloride and water and is in particular product gas from the gas phase oxidation of HCl with oxygen, wherein the gas is cooled in the region of the gas guide pipes until HCl and water are condensed.

FIG. 1 shows a diagrammatic representation of a device according to one embodiment of the invention operated with the cooling medium and the gas to be quenched flowing counter-currently, as can be used, for example, for cooling, in accordance with methods of the invention, hot gases that condense partially or completely wherein the hot condensation product of which has corrosive properties. It will be clear to the person skilled in the art that individual features disclosed therein can also be incorporated into the more general context of the patent claims or can be combined therewith.

Referring to FIG. 1, the hot gas stream 1 enters the lower part of the quenching apparatus 2. After cooling and condensation, the cold gas stream 3 exits in the upper part. In the middle part of the quencher 2, the gas stream passes through gas guide pipes 4. The gas guide pipes stand in a cooling liquid 5, preferably water or acid, which consists of collected, cooled condensation product of the gas stream 1. The gas guide pipes 4 are held at their bottom end in a pipe base 20. At their top end, they are fixed by a supporting grid 24. The supporting grid allows the liquid 5 to pass freely. The liquid 5 is conveyed from the sump 6 of the quencher 2 via a circulatory pipe 7 with the pump 8 in its middle part. The liquid passes through the flange 25 at the bottom end of the gas guide pipes 4 into the quencher. Excess liquid 9 is drawn off. The heat exchanger 10 serves to cool the liquid in the circulatory pipe. In the middle part of the quencher 2, the liquid 5 flows into the gas guide pipes 4 at their upper end and runs down the inside of the pipes counter-currently to the ascending gas stream.

In order that the liquid 5 can be evenly distributed on the inside of the gas guide pipes, it is preferable to construct the end face of the pipes 4 as shown in FIG. 2, for example, with teeth 11. It is, however, possible to use any other type of liquid distribution, such as, for example, slots incorporated axially or tangentially into the upper end of the pipes. The gas stream is then cooled by the liquid that is running down and condenses partially or completely.

It is thereby desirable to prevent hot condensation product from coming into contact with the parts of the quencher 2 which it attacks corrosively. Such a condensation product is, for example, hot hydrochloric acid. Corrosive attack should be prevented, for example, at the gas inlet nozzle 12 or the wall 13 of the quencher or the pipe base 20.

Such corrosion prevention can be accomplished, for example, in the case of the region proximate to the gas inlet nozzle 12, by one or more, and preferably, a series of design features. First, the nozzle 12 can be protected against the incoming gas condensing on it by heating and/or insulation. FIG. 1 shows, for example, a double casing 14 for heating the inlet nozzle, which double casing 14 is provided via the nozzle 15 with a heating medium, such as, for example, steam or hot water or alternatively a heat transfer oil. The heating medium can be removed again via the nozzle 16. An alternative heating possibility would be, for example, an electrical heat conductor, which could be wound round the nozzle 12.

Further design features can independently or conjunctively assist in preventing wetting of the nozzle 12 with condensation product dripping from the pipes 4. The pipes 4, as shown in FIG. 1, can be spaced or positioned away from the nozzle 12. This is achieved in FIG. 1 in that the pipes 4 do not fill the entire cross-section of the quencher 2 but only a part thereof. That portion is of such a size that a splash guard 17 can be fitted between the nozzle 12 and the pipes 4. The splash guard is exposed on one side to hot gas and on the other side to condensation product. Therefore, the possibility that the condensation product will be heated and assume a temperature that leads to corrosive attack of the material of the splash guard cannot be ruled out. Because the splash guard does not constitute a wall to the outside, it is not required to be pressure-resistant. It can therefore be produced from a material that is not pressure-resistant but is very stable towards hot, corrosive liquids such as hot hydrochloric acid. For example, suitable materials therefore are silicon carbide or silicon nitride or other suitable ceramics materials or plastics materials.

In order to avoid wetting of the wall 13 with hot, corrosive condensation product, the middle part of the quencher 2, in which the pipes 4 are arranged, is flooded with cold condensation product. The cold condensation product, unlike the hot condensation product, is not so corrosive, so that suitable metal materials that are pressure-resistant can be used therefore.

Although the wall 13 in the upper part of the quencher 2, above the pipes 4, is no longer protected by cold condensation product, the gas in that region has already been cooled, so that no more hot condensation product can form.

In the lower part of the quencher 2, beneath the pipes 4, a plurality of features can be included to reduce or prevent corrosion at the inner surface 13. First, hot gas from the inlet nozzle 12 is prevented from reaching the wall by inserting the nozzle 12 through a cylindrical pipe 18. The pipe 18 may be wetted by hot, corrosive condensation product that drips from the pipes 4 and must therefore be produced from a material that is stable towards hot, corrosive liquids. Because the pipe 18 is not pressure-bearing, the same materials are suitable therefore as for the splash guard 17. In order to prevent hot gas from flowing beneath the pipe 18 and reaching the wall 13, the pipe 18 stands on a carrying ring 19 in the sump liquid 6. In order that hot gas does not flow between the pipe 18 and the pipe base 20 and reach the wall 13, the pipe 18 can be pressed against the pipe base 20 by a spring or biasing device 21. Because this pressing does not necessarily produce complete sealing, and because the nozzle 13 is inserted into the pipe 18 through an opening, further measures can preferably be taken to prevent the formation of hot, corrosive condensation product at the lower wall 13. To that end, a protective gas 23 can be passed via the nozzle 22 into the space between the lower wall 13 and the pipe 18. The protective gas can be an inert gas such as nitrogen or argon, but air or carbon dioxide could also be used. The nature of the protective gas depends on its suitability in the process for which the quencher is used. For an HCl oxidation process (Deacon process), a further particularly suitable protective gas can be oxygen, because that gas is used in the process for oxidising HCl gas to chlorine and therefore does not constitute a foreign component.

The protective gas prevents part of the gas stream 1 from flowing between the pipe 18 and the wall 13 after it has left the nozzle 12. The gas flow is prevented in that the protective gas 23 is only able to flow into the interior of the quencher through the gap between the pipe base 20 and the pipe 18 and through the gap between the nozzle 12 and the opening in the pipe 18. Because it has to flow through these two gaps, it prevents the incoming gas 1 from flowing through the two gaps in the opposite direction.

The pipe base 20 can also be protected from hot, corrosive condensation product by a series of measures. On one side of the pipe base 20 is the cooled condensation product, which likewise cools the pipe base. Although hot gases are able to condense on the other side, a cold film of condensation product forms as a result of the cooling of the pipe base, which film constitutes protection against the hot, corrosive liquid that has condensed thereon.

Cooling of the pipe base can be improved by further measures. For example, the pipe base can contain a copper core, which has particularly good thermal conductivity and accordingly results in a particularly small temperature difference between the cool side of the pipe base, on which there is the cooled condensation product, and the warm side, on which the gas condenses.

As a further measure, the pipe base itself can be cooled. To that end, it can, for example, be produced from two plates, groove-like channels being incorporated into one side of the first plate. The second plate is then placed on the side of the first plate into which the channels have been incorporated. When the two plates have been joined together in a suitable manner, for example by screwing, the pipe base has channels through which a cooling agent can flow.

Furthermore, the pipes 4 are not inserted flush into the pipe base 20 but project from the pipe base slightly. As a result, the hot gases are not guided into the pipes directly at the pipe base but at a distance therefrom. This has the advantage that the hot gases are not in direct contact with the pipe base at the entry into the pipes. Furthermore, the point at which the pipes 4 are guided through the pipe base 20 is protected against the high gas temperature by a film of liquid.

The pipes 4 themselves are exposed to attack by corrosive, hot condensation products. However, because, like the splash guard 17 and the pipe 18, they do not have to be pressure-bearing, they can be produced from the same materials as those components.

FIG. 3 shows a diagram of an apparatus for cooling, in accordance with another embodiment of the invention, hot gases that can be condensed partially or completely, in which the gas to be cooled and condensed and the cooling medium are guided concurrently. It is clear to the person skilled in the art that individual features disclosed therein can also be incorporated into the more general context of the patent claims or can be combined therewith. The apparatus shown in the mentioned figure and described in greater detail hereinbelow can be used in particular for cooling and condensing gases whose hot condensation products, for example aqueous hydrochloric acid, have corrosive properties.

The gas 1 to be cooled or condensed enters the upper part of the quenching apparatus 2 via a nozzle 3 in the form of a push-in pipe. From there, the gas, which is still hot, passes directly into a corrosion-resistant inner gas guide pipe 4 of the apparatus. Because the corrosion-resistant inner gas guide pipe 4 does not have to be pressure-resistant but simply dimensionally stable, suitable materials therefore, in addition, for example, to ceramics materials, are also temperature-resistant plastics materials. The push-in pipe 3 and the inner pipe 4 can preferably be arranged concentrically to one another, the inside diameter of the push-in pipe 3 typically being slightly smaller than, but at most the same size as, that of the corrosion-resistant inner pipe 4. Between the inner pipe 4 and the pressure-resistant jacket 5 of the apparatus there is cooling liquid 6, which is circulated continuously by pumping. At the upper end of the inner pipe, the cooling liquid 6 overflows and forms a film on the inside of the inner pipe 4, which film on the one hand protects the corrosion-resistant material of the inner pipe 4 from excessively high temperatures and on the other hand makes available a cold surface for the cooling and condensation of the hot gas. The vertical spacing between the push-in pipe 3 for the supply of gas and the corrosion-resistant inner pipe 4 must accordingly be sufficiently great that the liquid is able to flow unhindered over the upper edge of the inner pipe even under varying operating conditions. To that end, it may be expedient for the upper edge of the inner pipe 4 to be provided with teeth, as shown in FIG. 3, In addition, contact between the overflowing cooling liquid 6 and the hot push-in pipe 3 must be avoided, because it can lead to corrosion in the affected region of the push-in pipe 3.

In order further to prevent hot gas from passing through the gap between the push-in pipe 3 and the inner pipe 4 at the pressure-resistant jacket 5 of the apparatus, a dry protective gas 8 (i.e., seal gas) is conveyed constantly into the space above the gap, so that a sufficiently cold cushion of gas forms and the hot gas to be cooled is forced into the inner pipe 4. An additionally fitted inner cone 7 of corrosion-resistant material provides advantageous flow guiding for the seal gas. The choice of a suitable seal gas 8 is dependent substantially on the conditions of the process as a whole. In principle, however, inert gases such as nitrogen or argon, as well as air or carbon dioxide appear to be possible in particular. In the special case of an HCl oxidation process (Deacon process), it is possible to use oxygen as the seal gas 8, because oxygen is already required in the process of oxidising HCl gas to chlorine and accordingly does not constitute an additional component.

In addition to the influx of hot gas into the jacket region, undesirable cooling and partial condensation is also to be avoided in the push-in pipe 3 or on the inside walls thereof. This can occur if, for example, the stream of seal gas 8 effects marked cooling on the inside of the push-in pipe 3 supplying gas. In order to counteract this, the wall of the push-in pipe 3 is to be provided with a suitable insulation 9. Under certain circumstances, additional heating, for example by means of steam or electrical energy, is to be provided.

Finally, in the upper part of the inner pipe 4, but beneath the upper edge of the pipe, one or more spray nozzles 10 are arranged, with the aid of which cooling liquid is finely distributed in the gas space. The arrangement of spray nozzles can also be provided in several planes beneath one another. As a result, there is intensive contact between the gas to be cooled and condensed and the cooling medium, which leads to a sudden drop in temperature and to partial or optionally also complete condensation of the gas. The spray nozzles 10 and the feed pipe located in the inner pipe 4 and the nozzle fixing itself are to be constructed from a temperature and at the same time corrosion-resistant material, because here, as in the gas inlet region of the inner pipe 4, the hot gas comes into contact with components wetted by cooling liquid or condensation product. On the other hand, the feed pipe to the spray nozzles in the region of the pressure-resistant outside wall 5 can be produced from the same material as the wall itself, because here the temperature is approximately that of the cooling agent. A complete, pressure-resistant seal in the region where the feed pipe to the spray nozzles 10 passes through the inner pipe 4 is not necessary.

The gas, which has in the meantime been cooled, together with the cooling liquid or the condensation product then passes into the lower part of the quenching apparatus, which serves to separate the gas phase and the liquid phase. Contact between the gas or condensation product and the pressure-resistant outside wall 5 of the apparatus takes place here for the first time. However, because the gas and condensation product have already been cooled in the inner pipe 4, it is possible to use a material that is corrosion-resistant at a markedly lower temperature than that of the hot gas.

The uncondensed but cooled gas 11 leaves the apparatus via a gas outlet 12. Devices for guiding the gas stream 13, for example deflecting plates, can ensure that as little condensation product or coolant liquid as possible is discharged with the gas stream.

The liquid separated from the cooled gas is collected in the sump of the apparatus 14 and removed therefrom by means of a pump 15. Part of the liquid is first conveyed as cooling agent, via a circulatory pipe, to a heat exchanger 17, where it is cooled to a fixed temperature level, and is finally supplied as cooling agent to the spray nozzles 10 again and the overflow between the pressure-resistant jacket 5 and the inner pipe 4. A suitable control device ensures that the amount of cooling agent in the system remains approximately constant. The amount of liquid that forms as excess as a result of the condensation is removed as the condensation product 16.

Various embodiments of the present invention include devices for cooling hot gases (a quencher), which devices have a pressure-resistant wall (13) and at least one corrosion-resistant, internal gas guide pipe (4). Also included are such devices comprising at least a gas inlet (12), a pressure-resistant container (23) comprising the pressure resistant wall (13), a contact zone (4), a sump region (31) and a head region (32) for receiving a condensate (6), an outlet (33, 9) for the cooled gas (3), a recirculating loop (7, 8, 10, 25), which conveys condensate (6) from the sump region (31) via a heat exchanger (10) into the head region (32), wherein the contact zone (4) comprises one or more contact pipes (4) in which condensate (6) is brought into contact with the hot gas (1) from the corrosion-resistant internal gas guide pipe. Also included are such devices characterized in that the gas inlet (12) is arranged in the sump region (31) and the gas outlet (33) in the head region (32) of the container (2), so that the gas (1) in the contact pipe (4) is contacted counter-currently with the condensate (6) in the contact pipe (4); as well as devices characterized in that the gas inlet (9) is arranged in the head region (32) and the gas outlet (13) in the sump region (31) of the container (2), so that the gas (1) is contacted co-currently with the condensate (6) in the contact pipe (4). Included within the invention are devices as described above, wherein the pressure-resistant wall (13) of the device comprises a material selected from the group comprising steel, steel alloys, in particular with chromium, nickel or molybdenum, and tantalum and tantalum alloys, wherein the materials are optionally lined with plastic or other metallic materials or are at least partially coated. Also included are devices wherein the corrosion-resistant internal gas guide pipe (4) consists of a material selected from the group comprising graphite and modifications thereof, ceramics, and in particular silicon carbide and silicon nitride, quartz glass or plastics, and in particular fluorine-containing polymers, and particularly preferably tetrafluoroperfluoroalkoxy vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) or polyethylenechlorotrifluoroethylene (ECTFE).

Devices included within the invention include those characterized in that the gas inlet pipe (12, 9) is airtight and thermally insulated and/or heatable, and those characterized in that the sump region (31) and/or the head region (32) of the container (2) has an additional corrosion-resistant wall (18, 7) or coating at least in the sections contacted by the gas (1). Various preferred devices according to the invention can be characterized in that the intermediate space between the pressure-resistant wall (13/5) and the corrosion-resistant wall (18, 7) can be pressurized with a protective gas, and in particular with an inert gas. Various preferred devices according to the invention can be characterized in that, during operation, the gas guide pies (4) are surrounded externally by cooled condensate (6) which flows into the gas guide pipes (4) at the upper end of the gas guide pipes (4). Various preferred devices according to the invention can be characterized in that, during operation, the pressure-resistant wall is at least partially in contact with the condensate (6). Various preferred devices according to the invention can be characterized in that, during operation, condensate (6) is present between the pressure-resistant wall (13) and the gas guide pipes (4). Various preferred devices according to the invention can be characterized in that nozzles (10) are arranged in the upper section of the gas guide pipes (4) for injecting and in particular atomizing cooled condensate, and in particular in that the gas (1) to be cooled is conveyed co-currently with the condensate (6).

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.