HK1194322A - Process for production of sulphuric acid - Google Patents

Description

Process for producing sulfuric acid

The invention relates to a condenser designed to avoid downstream condensation problems, and to a condenser for use with a sulphuric acid condenser having 0.1-30% SO₂And SO₃ (SO_x) To produce concentrated sulfuric acid and oleum. The feed gas may originate from the combustion of sulphur and sulphur compounds, from the wet scrubbing of SO from metal sulphide roasting₂Gases, from thermal regeneration of spent sulfuric acid and sulfates or from enrichmentContaining H₂S, the combustion of the flue gas. SO of up to 99.995% in the feed gas_xIt is possible to recover concentrated sulfuric acid, typically 95-99.5% by weight, and/or with up to 25% by weight SO₃Oleum (ii). By ensuring conditions external to the condenser that are not conducive to condensation of sulfuric acid droplets, the methods of the present disclosure are directed to avoiding corrosion of hot sulfuric acid droplets in process equipment.

It is known to catalyze SO in two steps₂Conversion and intermediate absorption of SO in a process involving both intermediate and final absorption or condensation steps₃Or condensation of H₂SO₄From a content of up to 30% by volume SO₂Strong SO of₂Production of concentrated sulfuric acid from gas, in which SO₂The conversion rate is as high as 99.9% or more. In principle, by absorption of SO in the liquid phase₃To remove SO in the gas phase₃Transfer to the liquid phase and by condensation, H₂SO₄The vapor is transferred to the liquid phase, where the gas is cooled below its sulfuric acid dew point either by direct contact with a circulating acid used as a coolant or in a falling film condenser, where the gas is cooled below its dew point and the acid condenses on the surface of an air-cooled glass tube.

Our U.S. patent No. 7,361,326 discloses a method for preparing a mixture of compounds having up to 30% SO₂And H₂O/SO₂A dual condensation process for producing concentrated sulfuric acid from a feed gas having a ratio greater than about 1. In the first step of the process, most of the SO₂Conversion to SO₃The process gas is then passed to an intermediate condenser, where the SO is introduced in a packed tower cooled by circulating acid or in vertical air-cooled glass tubes₃And H₂SO₄The vapour is condensed to concentrated sulfuric acid, wherein the process gas flows upwards or downwards in the tubes. The latter is mentioned as an option to avoid flooding at high gas velocities, but is believed to bring the disadvantage that it produces sulfuric acid with a low concentration (70-85 wt.%), thus requiring a subsequent concentration stage, such as a packed column, to reach the desired sulfuric acid concentration of 95 wt.% or more. Passing the process gas exiting the intermediate condenser over a second SO₂Transformation ofStep (ii) and subsequently, with the addition of particles, to a final wet condensation stage.

In the prior art, the process gas stream exiting the condenser glass tube is a gas at or near condensing conditions, depending on the nature of the condenser. Condensed concentrated H₂SO₄And (4) high corrosion. Therefore, for this part of the process layout, expensive equipment with lining surfaces or made of glass is necessary, at least before the condensation conditions are overcome, for example by diluting or heating the process stream with air.

Similarly, in other arrangements the output from the condenser may be associated with undesirable condensation immediately downstream of the condenser, with negative chemical or corrosive effects.

It is therefore an object of the present disclosure to overcome the disadvantages associated with the prior art, wherein it is necessary to design an intermediate apparatus to overcome the negative consequences of condensation, such as the need to withstand the conditions of condensing sulfuric acid.

This object is met by providing a condenser comprising: wherein the process gas containing condensable components is reheated to a temperature above the condensing conditions such that the process gas flowing from the condenser to downstream equipment does not condense and, in the case of corrosive condensable liquids, the equipment may be produced from standard carbon steel.

For the purposes of this application, the following terms should be taken:

the dew point of a gas component is the temperature/pressure at which the component condenses from the gas mixture.

A gas containing one or more components that are condensable under condition Y under condition X is understood to be a composition of: in the gaseous state under conditions X (temperature and pressure), but in conditions Y (lower temperature and/or higher pressure) a portion will condense as a liquid. When conditions are not mentioned (i.e., a gas containing one or more condensable components), condition Y is assumed to be atmospheric and room temperature, while condition X is assumed to be a higher temperature and/or lower pressure, such that the gas "exceeds the dew point," i.e., does not condense. The term "condensable gas" is understood to mean a gas containing one or more condensable components at room temperature and atmospheric pressure.

A "condenser" is understood to be a process unit in which heat exchange takes place between a warm process gas and a heat transfer medium, so that if the warm process gas contains condensable components, the components condense inside the condenser.

By "condensation side or process gas side of the condenser" is understood that the condenser side is provided for a process gas stream containing a stream of condensable components, whether or not conditions are such that condensation actually occurs.

The "heat transfer medium side of the condenser" is understood to be the side of the condenser where the heat transfer medium flows.

By "condensate" is understood a liquid formed by cooling a gas containing condensable components.

"upstream with respect to a location" is understood to be at a location closer to the inlet during typical operation.

"downstream with respect to a location" is understood to be at a location closer to the outlet during typical operation.

For a condenser unit, the upstream and downstream portions should be defined by the process gas side rather than the typical flow direction of the heat transfer medium. By "upstream process gas cooling zone" is understood a zone on the process gas side of the condenser, which is close to the inlet of the process gas to the condenser. By "downstream process gas cooling zone" is understood a zone on the process gas side of the condenser, which is close to the outlet of the process gas from the condenser.

By "process gas reheating zone" is understood a zone on the process gas side of the condenser in which the process gas is reheated.

Countercurrent flow is to be understood as two flows wherein the flows are in opposite or substantially opposite directions.

Cross-flow is understood to be two flows wherein the flow is in a vertical or substantially vertical direction.

Throughout this application, a compound may be referred to by a chemical formula, chemical name, or colloquial name. These should be understood as being entirely synonymous and should not be given special meaning by such difference in terminology.

According to the invention, the object of avoiding condensation problems is met by a condenser having a process gas side and a heat transfer medium side,

the condenser is arranged to feed hot process gas containing condensable components to the inlet of the condensing side,

and is further arranged to take cooled process gas from the outlet of the condensation side,

and even further arranged to take off condensate at a location close to one end of the condenser,

and the condenser having a process gas side is divided into a process gas cooling zone provided with a cold heat transfer medium inlet and a heated heat transfer medium outlet and a process gas reheating zone,

the process gas reheating section is downstream of the process gas cooling section and is arranged to reheat the process gas with the associated benefit that the process gas leaving the condenser is substantially not condensed.

In another embodiment, where the process gas side of the process gas reheating zone is arranged to receive thermal energy from a heated heat transfer medium, a related benefit is improved thermal efficiency by recovering the heat released in the condenser.

Another embodiment provides for counter-current flow of the heat transfer medium and the process gas in the reheating zone, with the associated benefit of improved heat transfer from the heat transfer medium to the process gas.

In another embodiment, the condenser is arranged such that the heat transfer medium and the process gas in the reheating zone operate in cross-flow, with the associated benefit of a simple physical structure of the reheating zone.

In another embodiment, the condenser is arranged to withdraw condensate close to the process gas inlet, with the associated benefit of improved condensing efficiency, thereby avoiding subsequent condensation of condensate.

In another embodiment, the condensate comprises sulfuric acid or oleum, providing the above benefits, particularly for sulfuric acid or oleum production processes.

In another embodiment, the condenser is arranged with the process gas side separated from the heat exchange medium by glass, with the associated benefit of a high degree of corrosion resistance in the condenser.

In another embodiment, the condenser comprises a glass tube configured to have a flow of process gas on the inside of the glass tube and a flow of heat transfer medium on the outside of the glass tube, with the associated benefit of high surface area of the thermal interface between the process gas side and the heat transfer medium side.

In another embodiment, the condenser comprises a glass tube configured to have a flow of heat transfer medium on the inside of the glass tube and a flow of process gas on the outside of the glass tube, with the associated benefit that the physical orientation of the glass tube is independent of condensate removal, e.g., allowing horizontal installation of the glass tube.

In another embodiment, the condenser further comprises a flow restriction element separating the flow of the heat transfer medium on the heat transfer medium side of the condensing zone and the reheat zone, with the associated benefit of thermal separation of the condensing zone and the reheat zone.

In another embodiment, the flow restriction element comprises one or more stabilizing elements connected to a metal plate, with the associated benefit of obtaining high pressure stability of the flow restriction element, while requiring only a limited amount of material compared to a large plate with the same pressure stability.

In another embodiment, the condenser further comprises one or more turbulence-enhancing elements, with the associated benefit of providing improved contact of the process gas with the tube wall.

In another embodiment, the condenser further comprises one or more securing elements, such as individual notches, with the associated benefit of providing a means of securing the positional elements inside the tube with minimal alteration to the tube.

In another embodiment, the condenser further comprises a retaining shoulder that is part of the glass tube having a smaller internal cross-sectional area, with the associated benefit of providing a means of retaining the positional element inside the tube without compromising the overall external shape of the tube.

In another embodiment, one or more turbulence-enhancing elements are provided fixed by being suspended from a fixed element, with the associated benefit of avoiding deformation of the droplet coalescing element due to the weight of the turbulence-enhancing element.

In another embodiment, one or more turbulence-enhancing elements are provided to be fixed by being placed on a fixing element, with the associated benefit of avoiding tensile stresses in the turbulence-enhancing elements.

In another embodiment, the condenser further comprises droplet coalescing elements, with the associated benefit of mist and droplet coalescence, such that condensation can be maximized prior to reheating the process gas.

In another embodiment, the stationary element engages the droplet coalescer element such that movement of the droplet coalescer element is restricted, with the associated benefit that the droplet coalescer element is fixed in a position where condensation can be maximized prior to reheating the process gas.

In another embodiment, the condenser further comprises a restriction element configured to restrict movement of the droplet coalescer element, with the associated benefit of further fixing the position of the droplet coalescer element.

In another embodiment where the condenser has a tube shoulder as the stationary element, the restriction element further comprises one or more sheet elements having narrow and wide ends and arranged for mechanical engagement of their wide ends with the stationary shoulder of the tube wall such that movement of the restriction element is restricted, with the associated benefit of fixing the location of the droplet coalescer element with minimal additional pressure loss over the combined droplet coalescer element and stationary element.

In another embodiment where the condenser has one or more tube notches as fixing elements, the limiting element further comprises an annular element arranged for mechanical engagement of its outer periphery with the fixing element such that movement of the limiting element is limited, with the associated benefit of stable contact with the entire tube wall outer periphery.

An alternative embodiment of the invention is a process for condensing sulfuric acid and/or oleum in a process gas, the process comprising the steps of:

(i) the process gas is passed to a sulfuric acid condensation stage according to the present disclosure, wherein the inlet temperature exceeds the dew point of the sulfuric acid,

(ii) the process gas is cooled to below the dew point of sulfuric acid,

(iii) condensing and withdrawing sulfuric acid, and

(iv) reheating the process gas in the condenser stage beyond the sulphuric acid dew point has the associated benefit over the prior art in that the requirement for corrosion resistant materials downstream of the condenser is reduced as the risk of downstream condensation is removed.

In another embodiment, the temperature of the process gas at the outlet of the condenser stage exceeds the sulfuric acid dew point by at least 10 ℃ after reheating in step (iv), with the associated benefit that the requirement for corrosion resistant materials downstream of the condenser is reduced, since the risk of downstream condensation is removed, with sufficient margin of safety.

Another alternative embodiment of the invention relates to a process for producing sulfuric acid and/or oleum in a process gas, comprising the steps of:

(a) providing a mixture containing 0.1-30 mol% SO₂The feed process gas of (a);

(b) make the feed material pass throughThe process gas passes through the first SO₂A conversion step in which SO is present in one or more catalyst beds₂Is oxidized into SO₃；

(c) Will come from the first SO₂Containing SO of the conversion step₃Cooling the process gas to a temperature of 0-100 ℃ above the sulfuric acid dew point of the process gas; and

(d) the sulfuric acid in the process gas is condensed in a first condensation stage,

wherein the condenser stage is operated in accordance with the present disclosure, with the associated benefits of providing the benefits of the present disclosure for the production of sulfuric acid.

In another embodiment of the present invention, the process for producing sulfuric acid and/or oleum in a process gas further comprises the steps of:

(e) further reheating the resulting process gas stream from step (f) and passing the process gas to a second SO₂A conversion step in which the remaining SO is present in one or more catalyst beds₂Is oxidized into SO₃，

(g) Cooling the process gas to a temperature of 0-100 ℃ above its sulfuric acid dew point, and

(h) the process gas is then passed to a final condensation stage,

wherein at least one of the condenser stages (d) and (h) is operated in accordance with the present disclosure, a related benefit is to provide an increased level of sulfur dioxide removal.

Another embodiment relates to the inlet temperature of the process gas to the second catalytic unit being 350-₂/SO₃And (6) balancing optimization.

Another embodiment relates to the inlet temperature of the process gas to the second catalytic unit being 400-.

Another embodiment involves the addition of rich O₂Oxidizing agents in the form of gases, e.g. pure O₂The benefit is that less inert gas is added compared to atmospheric air, which again results in a reduced size of the process equipment, resulting in reduced costs.

These and other characteristics of the present disclosure will be apparent from the following description of preferred forms of embodiment, given by way of non-limiting example with reference to the accompanying drawings, in which:

FIG. 1 shows a reaction mixture containing SO according to the prior art₂Process gas production of H₂SO₄The process layout of (a) is described,

FIG. 2 shows a condenser utilizing the present disclosure, according to one embodiment of the present disclosure, from SO-containing gas₂Process gas production of H₂SO₄The process layout of (a) is described,

figure 3 shows condenser tubes for use in some embodiments of the present disclosure,

FIG. 4 shows a tube containing a fixation element for some embodiments of the present disclosure, and

fig. 5 shows an example of a restriction element for some embodiments of the present disclosure.

Using 2 condensation steps for SO₂The process according to the prior art of oxidation and subsequent condensation of concentrated sulfuric acid is shown in figure l. The main steps of the process include SO in the presence of a first catalyst in a first catalytic reactor 140₂Oxidizing, condensing SO produced in the intercondenser 142₃The remaining SO is oxidized as sulfuric acid in the second catalytic reactor 144₂And further condensing the remaining and generated SO in a final condenser 146₃The substantially clean process gas may then be sent to the atmosphere.

In this process, temperature control is necessary, in particular because of the SO in 140 and 142₂To SO₃Requires a minimum temperature, while high temperatures limit the SO₂With SO₃SO that a part of SO is₂Will not be oxidized at higher temperatures. Is easy to be formed by H₂O and SO₃More liquid H formed₂SO₄Very corrosive and not in the gaseous state, and therefore it is desirable to maintain the H content₂SO₄The process gas exceeds the dew point until it condenses, which essentially requires a temperature below the dew point and therefore a corrosion resistant material, such as a glass tube. Specifically, the process contemplates an inlet temperature of the catalyst bed of 370 ℃ and 500 ℃ and an inlet temperature of the condenser 142 of 5-100 ℃, preferably 10-70 ℃, or even more preferably 20-50 ℃, for example about 30 ℃ above the dew point of sulfuric acid.

In one embodiment of the process, the process gas 100 is directed to a first catalytic reactor 140 where most of the SO occurs₂And (4) oxidizing. The first catalytic reactor may be designed with one catalytic bed or multiple catalytic beds, and if the amount of sulphur dioxide is very high, it is desirable to take out the heat of reaction, for example in heat exchangers 130 and 132, to provide the reaction at a reduced temperature, SO that the inlet process gas 102 to the first condenser 142 is not subjected to SO₂With SO₃The balance between them.

In the intermediate condenser 142, if SO₃Is condensed into H₂SO₄At the outlet 106, SO₃May be sufficiently high that corrosion occurs.

The intercondenser 142 is configured to cool the process gas 102 entering the condensor at a typical temperature of 290 c. Cooling is typically performed by heat exchange with a heat transfer medium (e.g., air 120) that is at a lower temperature than the process gas. The condenser 142 must be configured to be compatible with the process gases and condensates, which may include corrosion resistance to corrosive condensable components, e.g., made of glass tubing or other corrosion resistant materials (e.g., ceramic tubing or lined with a protective coating).

Typically, the cooling zone 150 is a heat exchanger in which a heat transfer medium (e.g., air) flows counter-currently to the process gas. The benefit of the counter-current flow is that in the direction of flow of the process gas the temperature will decrease and thus the potential for condensation will increase. Thereby obtaining the highest level of condensation.

Typically the condenser is vertically equipped with a process gas inlet 102 at the bottom and the condensed liquid 114 is collected at the bottom, but in case the process gas flow is very high it may be preferable to co-current the condensed liquid flow with the gas to avoid overflow.

According to the prior art, the condenser is operated such that at all locations of the condenser, conditions are at or near the dew point of the condensable components. This is a natural consequence of the counter-current operation, since the temperature at all points of the condenser (except possibly immediately after the inlet) is in condensing conditions, and further downstream, the temperature is always lower.

Now, as illustrated in fig. 2, an alternative to the prior art was developed, including a condenser 142 according to the present disclosure, wherein a process gas cooling zone 150 is followed by a process gas reheating zone 152 in which the process gas is heated. To ensure successful reheating, the heat transfer medium of the cooling zone must be separated from the reheating zone. One way of doing this is to block the flow of the heat transfer medium from the cooling zone to the reheating zone. Secondly, a heat source must be provided for the heating zone. One possible way to provide heat to the heating zone 152 is to transfer the heated heat transfer medium in line 122 from the upstream portion of the condenser to the heat transfer medium side of the process gas reheating zone 152 at the downstream end of the condenser, thereby heating the process gas on the process gas side in a flow arrangement relative to the process gas, e.g., a cross-flow, co-current, or counter-current flow.

In particular embodiments of the present disclosure for H₂SO₄/SO₃The process of condensation, the process gas side and the heat transfer medium side, can be separated by flowing one side in the glass tube to provide corrosion resistance.

In one embodiment, the heat transfer medium stream may be inside the glass tube, while the sulfuric acid is condensed outside the tube. In this arrangement, the flow of heat transfer medium is defined by the connection of the tubes, and it is therefore simple to control which part of the condenser is withdrawn with the heat transfer medium heated. In this arrangement, the heating tubes are preferably arranged horizontally, so that they have an optimized heat exchange efficiency by generating a maximum turbulent flow. In this arrangement, the condenser walls must be made of a highly corrosion resistant material.

In an alternative embodiment, the stream inside the glass tube is a stream containing condensable H₂SO₄Such that condensation occurs inside the tubes and condensate can collect in the bottom region of the condenser, which can be at the level of or below the gas inlet, i.e. near the end of the condenser. In this case, a flow restriction element 154 on the heat transfer medium side is beneficial to ensure that cold heat transfer medium used to cool the process gas in the cooling section 150 is prevented from entering the heat transfer medium side of the process gas reheating zone 152. It must be appreciated that when the heated heat transfer medium is directed to the reheat zone gas, the pressure on the cold side of the flow restriction element 154 may generally be higher than the pressure on the warm side, and thus the flow restriction element 154 must be designed to be substantially flow tight to the heat transfer medium, for example, by providing a gasket of corrosion resistant material (e.g., fluoropolymer, including PTFE or PFA), but no absolute seal is required.

Alternatively, other heat sources besides heated heat transfer media may be used as heat sources for the reheating zone 152, primarily other warm process gases, although any other heating means, such as electrical heating, may be used.

For condensers in which the process gas flows inside the glass tube, the flow restriction element 154 on the heat exchange medium side can be prepared as a tube dividing plate in which holes matching the tubes are arranged. In particular, the manifold plate may be made of steel plate or of a steel plate-based foil structure with stabilizers. When the condensable components are corrosive, the plates may be made of corrosion resistant steel or another corrosion resistant material, or they may be surface protected by a suitable material (e.g., a fluoropolymer, including PTFE or PFA).

In the prior art, for SO₃The specific process of condensation, the condenser, is usually made of tubes made of a corrosion resistant material (e.g. glass). The tubes are generally round. Inside the tubes, turbulence-enhancing elements (e.g., spirals) are typically installed to aid in heat transfer and condensation, and plugs of material are provided to aid in condensation of the condensable liquid.

According to the disclosure for H₂SO₄/SO₃The specific process of condensation, the condenser process gas side, is made of a corrosion resistant material (typically a glass tube), but tubes or other geometries made of ceramic or coated materials may also be used. The tubes may be generally round, but they may have any suitable shape. As illustrated in fig. 3, the tube 300 may be configured to mount turbulence-enhancing elements (e.g., spiral 306) to aid in heat transfer by creating turbulent flow with minimal pressure loss. Furthermore, the tube may also be provided with a droplet coalescing element 302, such as a demister, i.e. a plug of material, to assist droplet formation, thereby condensing condensable liquids. By introducing a heating zone in the condenser, the tube is preferably arranged with droplet coalescing elements near the downstream end of the cooling section, and the tube may also be arranged with second turbulence-enhancing elements 304, 308 in the heating section.

When the disclosed condenser is used in a condensation process, wherein a process gas flows inside a glass tube 300, it may be advantageously arranged to comprise process support elements, such as turbulence-enhancing elements, e.g. spirals 304, 306, 308, inside the tube, and a droplet coalescing element 302. These process support elements are not necessary for the operation of the present disclosure, but their presence can contribute to the efficiency of the present disclosure. In addition, the specific arrangement of the condenser may include elements for holding these process support elements in the correct position.

Such condensation process enhancement elements may also be used with benefits in other condensation processes.

In the case of condensing corrosive condensable liquids (e.g., sulfuric acid), the process support element may advantageously be made of a highly corrosion resistant material (e.g., fluoropolymer, including PTFE or PFA).

Proximate the outlet of the condensation zone of the condenser tubes, a droplet coalescing element 302 may be disposed. While it is important on the one hand that the pressure loss over the droplet coalescing element is low, it is also important that the droplet coalescing element is able to collect a significant portion of the mist and droplets of condensable components prior to the heating zone to ensure that condensed liquid is not reheated and evaporated, but rather collected as droplets of condensate.

By means of the fixing elements in the tube, the positioning of the turbulence-enhancing elements can be ensured. These securing elements may include one or more partial or complete restrictions on the inner diameter of the glass tube, including a separate notch 406 of the glass tube, as shown in FIG. 4, or a shoulder 410 formed by reducing the diameter of the glass tube. The fixing element may be arranged at the upstream or downstream end of the turbulence-enhancing element 304, 306, 312, such that the position of the turbulence-enhancing element is fixed by placing the turbulence-enhancing element on the fixing element or by hanging from the fixing element.

It may also be beneficial to restrict movement of the droplet coalescer 302 element so that condensing the process gas does not change the position of the droplet coalescer element. As illustrated in fig. 3 and 4, this may be accomplished by one or more notches of the tubes 306, 310, 406, 410, including forming the shoulders 310, 410. Further, the condenser may be arranged with the droplet coalescer elements 302 placed on additional restriction elements 306, the restriction elements 306 contacting one or more notches of the tubes and supporting the droplet coalescer elements, or as illustrated in fig. 3A, with turbulence enhancing elements 304 fixing the position of the droplet coalescer elements 302. In fig. 5 specific examples of these further restriction elements are shown, including rings, e.g. 500 and 502, arranged to be placed on one or more recesses, or in case of a shrinking of the shoulder of the tube, the restriction elements have only few contact points with the tube wall, e.g. plates 504 arranged to be placed on the shrinking of the tube, cross elements 506, rings with protrusions 508 or elongated elements 510 around which droplet coalescing elements may be arranged. Common to all of these elements is that they limit the free movement of the droplet coalescer element so that the position of the droplet coalescer element is properly defined and condensation is completed before the droplets enter the reheat region.

Another benefit of using the disclosed condenser includes use as a final condenser before stack. In the prior art, it is common practice to add hot dilution air at this location to avoid H₂SO₄Condensing, but reusing the thermal energy in the heat transfer medium in a condenser according to the present disclosure more effectively avoids these problems.

Examples

Example 1

A first exemplary embodiment according to the prior art comprises treating a sulfuric acid plant containing H in WSA₂Tail gas of S. The process consists of 3 steps:

A) combustion, H₂S is oxidized to SO₂

B) SO₂Transformation, SO₂And O₂Reacted and converted to SO₃

C) Condensation, SO₃Hydration to H₂SO₄(gas) and condensed to H₂SO₄(liquid)

According to fig. 1, the process was operated under the process conditions shown in table 1, such that the process gas outlet temperature of the condenser was below the sulfuric acid dew point, and corrosion resistant materials were required downstream of the condenser.

TABLE 1

The process gas leaves the condenser at 110 c, about 18 c below the sulfuric acid dew point. Thus, it contains liquid droplets of sulfuric acid, making it very corrosive.

Example 2

A second exemplary embodiment according to the present disclosure is shown in fig. 2 and table 2. The conditions here correspond to those of example 1, except that the condenser is operated according to the present disclosure, e.g., with a reheating zone, such that the process gas outlet temperature of the condenser exceeds the sulfuric acid dew point, such that corrosion resistant materials do not have to be used downstream of the condenser.

TABLE 2

In this example, the process gas leaves the condenser at 180 ℃, which exceeds the sulfuric acid dew point by about 50 ℃. Thus, the gas is dry and no longer corrosive.

Claims (15)

1. A condenser having a process gas side and a heat transfer medium side,

the condenser is arranged to feed hot process gas containing condensable components to the inlet of the condensing side,

and further arranged to take cooled process gas from an outlet at the condensing side,

and even further arranged to take off condensate at a location close to one end of the condenser,

and the condenser with the process gas side is divided into a process gas cooling zone and a process gas reheating zone,

the process gas cooling zone is provided with a cold heat transfer medium inlet and a heated heat transfer medium outlet,

the process gas reheating zone is downstream of the process gas cooling section and is arranged to reheat the process gas.

2. The condenser of claim 1, wherein said condenser is configured such that a process gas side of said process gas reheating zone receives thermal energy from said heated heat transfer medium.

3. The condenser of claim 2, configured such that the heat transfer medium and the process gas in the reheating zone flow in countercurrent.

4. The condenser of claim 2, configured such that the heat transfer medium and the process gas in the reheating zone operate in cross-flow.

5. The condenser of any one of the above claims, wherein the condensate comprises sulfuric acid or oleum.

6. The condenser of any one of the preceding claims, wherein the condenser is arranged such that the process gas side is separated from the heat exchange medium side by glass.

7. The condenser of claim 6, comprising one or more glass tubes arranged to have a flow of process gas on the inside of the glass tubes and a flow of heat transfer medium on the outside of the glass tubes.

8. The condenser of claim 7, comprising one or more glass tubes arranged to have a flow of heat transfer medium on the inside of the glass tubes and a flow of process gas on the outside of the glass tubes.

9. The condenser of any one of the preceding claims, further comprising a flow restriction element that separates the flow of heat transfer medium on the heat transfer medium side of the condensing zone and the reheating zone.

10. The condenser flow restriction element of claim 9, configured as a stabilizing element attached to a metal plate.

11. A process for condensing sulfuric acid and/or oleum in a process gas, the process comprising the steps of:

(i) passing the process gas to a sulphuric acid condensation stage according to any of claims 1 to 10, wherein the inlet temperature exceeds the dew point of sulphuric acid,

(ii) cooling the process gas to below the dew point of sulfuric acid,

(iii) condensing and withdrawing sulfuric acid, and

(iv) reheating the process gas within the condenser stage to above the sulfuric acid dew point.

12. The process of claim 11, wherein the temperature of the process gas at the outlet of the condenser stage exceeds the dew point of sulfuric acid by at least 10 ℃ after reheating in step (iv).

13. A process for producing sulfuric acid and/or oleum in a process gas, the process comprising the steps of:

(a) providing a mixture containing 0.1-30 mol% SO₂The feed process gas of (a);

(b) passing the feed process gas over a first SO₂A conversion step in which SO is present in one or more catalyst beds₂Is oxidized into SO₃；

(c) Future of the dayFrom the first SO₂Containing SO of the conversion step₃Cooling the process gas to a temperature of 0-100 ℃ above the sulfuric acid dew point of the process gas; and

(d) the sulfuric acid in the process gas is condensed in a first condensation stage,

wherein the condenser stage operates according to any one of claims 11 or 12.

14. The process for producing sulfuric acid and/or oleum in a process gas of claim 13, further comprising the steps of:

(e) further reheating the resulting process gas stream from step (f) and passing the process gas to a second SO₂A conversion step in which the remaining SO is present in one or more catalyst beds₂Is oxidized into SO₃，

(g) Cooling the process gas to a temperature of 0-100 ℃ above its sulfuric acid dew point, and

(h) the process gas is then passed to a final condensation stage,

wherein at least one of the condenser stages (d) and (h) operates according to any one of claims 22 or 23.

15. The process of claim 13 or 14, wherein the oxidant is enriched in O₂In the form of a gas, e.g. pure O₂。