METHOD FOR DETERMINING SULFATION PERFORMANCE IN FLUE GAS

Description

[0001] The invention relates to a method for determining a sulfation performance in flue gas.

[0002] Flue gases typically arise from the combustion of fuels. These can be fossil fuels such as coal, oil, or gas; renewable fuels such as biomass; or waste and waste-like fuels such as sewage sludge or by-products of industrial processes. Such fuels are regularly burned in power plants to utilize the resulting heat, for example, to drive steam-driven turbines or to generate district heating. Flue gases also arise from the thermal treatment of materials, such as metal recycling. In these processes, the resulting heat can also be used for energy generation in a downstream boiler.

[0003] Flue gases often have a very high temperature of several hundred °C and frequently contain aggressive chemical substances, such as halogen salts. When biomass is used as fuel, potassium chloride (KCl), for example, is often produced. When waste, such as normal household waste, is used as fuel, substances such as sodium chloride (NaCl), calcium chloride (CaCl 2 ), lead chloride (PbCl 2 ), and zinc chloride (ZnCl 2 ) are produced. When waste wood is used as fuel, potassium chloride (KCl), lead chloride (PbCl 2 ), and zinc chloride (ZnCl 2 ) are produced. In addition, mixed salts of the various halogen salts can occur, which can have different physical and chemical behavior than the pure salts in terms of corrosion effects.

[0004] Such substances lead to corrosion of the materials from which the boiler, including any flue gas ducts, is constructed. Therefore, it is advantageous if such substances are chemically decomposed as quickly as possible after any deposits on a boiler wall or even before they form. It is known that sulfur trioxide (SO3) can decompose these and other corrosive flue gas components, typically converting chlorine salts into sulfates, or, more generally, converting halogen salts into other salts, particularly sulfates. Therefore, a certain amount of sulfur trioxide in the flue gas is desirable.

[0005] Depending on the fuel, the sulfur trioxide produced during combustion may not be sufficient to effectively prevent corrosion. This is primarily due to the fact that the production of sulfur trioxide competes with the production of sulfur dioxide (SO2). Therefore, mechanisms have already been developed that can add sulfur trioxide to the flue gas or generate sulfur trioxide in the flue gas. This specifically increases the sulfation capacity, i.e., the ability of flue gas to remove or decompose halogen salts.

[0006] However, it has proven difficult to measure sulfation performance in flue gas, which in turn makes it difficult to evaluate sulfur trioxide generation and dosing procedures.

[0007] Document US 2007 / 0119352 A1 discloses a method for controlling slag and corrosion. This involves identifying the location of a slag-caused problem and remediating it using suitable chemicals.

[0008] The document Spiegel Wolfgang et al., "Corrosion protection and material selection in waste incineration plants, refuse-derived fuel power plants and biomass plants", Energy from Waste, Volume 12, TK Verlag Karl Thomé-Kozmiensky, (2015), pages 223 - 240, ISBN 978-3-944310-18-3, XP055790792, discloses material probes for the investigation of corrosion in power plants.

[0009] The document Spiegel Wolfgang, "High-temperature corrosion in waste incineration plants, biomass and renewable energy sources", (200911), URL: https: / / tu-dresden.de / ing / maschinenwesen / iet / ressourcen / dateien / kwt / lehre / stubi / Korrosion_Spie gel.pdf?lang=en, XP055791051, discloses information on corrosion processes in power plants.

[0010] It is therefore an object of the invention to provide possibilities by which sulfation performance can be determined. This is achieved according to the invention by a method according to claim 1. Advantageous embodiments can be found, for example, in the subclaims. The content of the claims is incorporated into the content of the description by express reference.

[0011] Described herein is a probe for determining sulfation performance in flue gas, which is used in particular within the scope of the claimed method. The probe comprises a carrier medium that can be conveniently attached to a boiler wall. The probe comprises a sacrificial layer that is arranged and / or applied to the outside of the carrier medium and that conveniently contains a sacrificial material made of a halogen salt.

[0012] Using such a probe, sulfation performance can be easily determined, for example, by introducing it into flue gas and comparing the states of the sacrificial material before and after contact with the flue gas. Since sulfur trioxide is responsible for sulfation performance and attacks halogen salts, a significant change in the sacrificial material, particularly a significant chemical transformation or significant removal of the sacrificial material, can be inferred from a high sulfation performance, and vice versa. In particular, a conversion of a halogen salt into a sulfate can occur, typically with the cation remaining constant.

[0013] The cation of the halogen salt can be understood as a tracer, which is introduced into the flue gas and is typically not present in the flue gas itself, or at least only weakly. In an ideal process, the cation remains at the probe, meaning it is neither released from the probe into the flue gas nor deposited from the flue gas. The change in the compound present in the flue gas can be used to characterize the sulfation performance.

[0014] A halogen salt as a sacrificial material is attacked much more intensively by sulfur trioxide than by sulfur dioxide, since the reaction of sulfur dioxide with a halogen salt requires an additional oxygen atom as a reactant to achieve a stoichiometrically correct reaction equation. The sulfation probe described here thus specifically measures the sulfation performance based on sulfur trioxide. For example, during the combustion of fossil fuels such as coal, a constant ratio between sulfur trioxide and sulfur dioxide can be established, with typically significantly more sulfur dioxide being produced than sulfur trioxide.During the combustion of renewable fuels such as biomass or waste, the actual amount of sulfur trioxide present in flue gases typically depends not only on the amount of sulfur trioxide produced during combustion, but also on any chlorine salts present in the fuel, which react directly with the resulting sulfur trioxide, rendering it unavailable for desired sulfation in flue gases. Precisely because of these effects, the ability to specifically measure sulfation performance using the probe described here is particularly advantageous, as changes in sulfation performance due to different fuels or fuel compositions can also be detected.

[0015] The carrier medium can be designed, in particular, to support the sacrificial layer. It is preferably designed to have a large surface area. In a particularly simple case, however, the carrier medium can also be designed, for example, to provide a simple shell, a surface, and / or a holder for the sacrificial material. The carrier medium can be attached to the vessel wall in various ways. Exemplary embodiments are described below.

[0016] The sacrificial material or layer is typically applied in such a way that it comes into contact with the flue gas flowing around the probe. This allows for measurement of the sulfation performance, as the sulfation performance of the flue gas acts directly on the sacrificial material. This can be understood, in particular, as an external arrangement.

[0017] It should be mentioned that instead of a halogen salt, a reactant can generally be used as a sacrificial material, which does not necessarily have to be a halogen salt.

[0018] It should be understood that the sacrificial layer is typically a deliberately applied layer containing the sacrificial material, with a quantity of sacrificial material typically being used such that, after a specified period of time during which the probe is intended to remain in the flue gas, a portion of the sacrificial material is typically still present. This distinguishes the probe described herein, in particular, from components that intentionally or unintentionally contain halogen salts, but which are unsuitable for the intended use just described due to the insufficient amount of halogen salt they contain. Instead of the terms "sacrificial layer" and "sacrificial material," the terms "reaction layer" and "reaction material" can also be used.Ultimately, the flue gas is exposed to a material with which the sulfur trioxide it contains can react, transforming it into a different chemical compound, at least partially and, in particular, while completely or largely retaining the cations. This is not to be confused with sacrificial layers, which are used, for example, to protect other materials. The sacrificial layer is not a dissolving layer; rather, chemical reactions take place within it, changing its chemical composition.

[0019] The sacrificial layer is offered in particular to the flowing flue gas.

[0020] The halogen salt can, in particular, be a water-soluble halogen salt. This offers the advantage that, after a probe has been taken from the flue gas, the amount of halogen salt still present can be easily determined by dissolving the halogen salt in water and determining the amount present using wet chemistry, spectroscopic methods, or other methods. For example, a titration can be carried out to determine the residual amount of halogen salt. It should be understood that, instead of a water-soluble halogen salt, a halogen salt that is soluble in another solvent can also be used. A corresponding evaluation using this solvent is typically possible. Solubility in a solvent is understood in particular to mean that the respective halogen salt dissolves completely or at least almost completely in water or in the respective solvent at typical quantitative ratios.Solubility can be assumed, for example, at values ​​of a soluble mass of the halogen salt in a volume of solvent of at least 300 g / l or at least 350 g / l. Insolubility or at least de facto or substantial insolubility can be assumed, for example, at values ​​of at most 1 g / l or at most 0.5 g / l. The values ​​can refer, for example, to 20°C or room temperature. In particular, a halogen salt can be used whose value of the soluble mass of the halogen salt in a volume of water or another solvent is at least a factor of 100, 200, 300, 400, 500 or 1000 greater than the corresponding value of the associated sulfate with the same cation.

[0021] It should be understood that the probe can also be evaluated in other ways, for example by visual observation or by scraping off the sacrificial layer or sacrificial material, by measuring a change in the weight of the sacrificial layer or sacrificial material, or by preparing the sacrificial layer for light microscopy or scanning electron microscopy examination.

[0022] The halogen salt can, in particular, be an alkaline earth halide. Such alkaline earth halides have properties that are advantageous for the application relevant here; in particular, they allow for a precise determination of the sulfation performance.

[0023] The halogen salt can, in particular, contain strontium or barium as alkaline earth metals. These have the particular advantage of forming readily soluble halogen salts and of not being, or at least not particularly, toxic. Furthermore, they have the advantage of being rarely found in typical flue gases, so interference with the determination of sulfation performance is not expected.

[0024] The halogen salt can, in particular, contain chlorine as the halide. This has advantageous properties for measuring sulfation performance, as it forms particularly soluble halogen salts, and such halogen salts are converted by sulfation with sulfur trioxide, in particular into a corresponding sulfate.

[0025] The halogen salt can be, in particular, strontium chloride or barium chloride. Such halogen salts have proven particularly advantageous for the application in question here, as they are non-toxic or at least only slightly toxic, hardly any interference is to be expected, and they can be easily analyzed due to their good solubility. Furthermore, they are well converted at high sulfation efficiency, but correspondingly less so at low sulfation efficiency.

[0026] It should be understood that the aforementioned embodiments of the halogen salt can also be combined with one another. For example, the sacrificial material can consist of several components, with each component being designed according to one of the embodiments just described or otherwise described herein.

[0027] The halogen salt can be non-volatile, particularly up to temperatures of 350°C, 400°C, 450°C, or 500°C, with the aim of preventing thermal erosion of the metallic and / or cationic component. This prevents the metallic and / or cationic component from moving away from the probe simply due to the temperature, thus distorting the measurement. In particular, a non-volatile substance can be understood as one whose vapor pressure at a given temperature is so low that no disruptive evaporation losses occur.

[0028] It should be noted that it is not absolutely necessary for the halogen salt to be non-volatile up to the flue gas temperature. The probe is typically attached to a boiler wall and is thus already passively cooled. Active cooling may also be provided, or alternatively. This ensures that the sacrificial layer typically has a temperature below the flue gas temperature, which reduces the respective vapor pressures of the materials.

[0029] The probe preferably has at least one thermocouple for measuring a temperature. This allows the temperature of the probe to be monitored in a preferred manner. This can increase the informative value of a measurement.

[0030] According to an advantageous embodiment, the probe can have a fastening device for attaching the carrier medium to the boiler wall. This allows for a special device for fastening to the boiler wall to be provided, which can, for example, be optimized for such a fastening.

[0031] The fastening device can, in particular, comprise a protruding pin that can be passed through a hole in the boiler wall. This enables simple and reliable fastening of the probe to a boiler wall. In particular, the probe can thus be attached to a web between two tubes of a heat exchanger. However, other mounting options are also conceivable. The fastening device can also be designed to attach the probe to another probe.

[0032] The fastening device can also be formed integrally with the carrier medium. This can be understood, in particular, that the fastening device and carrier medium are not clearly distinguishable from one another, but rather merge into one another. For example, they can be formed from the same material.

[0033] Even independent of an integral design, the fastening device can be made of the same material as the carrier medium. This allows for simple manufacturing, for example. However, different materials can also be used.

[0034] According to one embodiment, the fastening device can be designed as a fastening section of the carrier medium. For this purpose, the fastening section can, for example, be a component of the carrier medium. This can, in particular, be adapted for fastening to a boiler wall, for example, by being pin-shaped or conical.

[0035] According to one embodiment, the fastening section can be conical. This allows, for example, adaptation to a conical hole in a boiler wall, particularly in a web of the boiler wall. The use of such a conical design, particularly in conjunction with a conical hole, can result in a particularly easy-to-implement and particularly tight seal of the boiler wall using the fastening section.

[0036] The fastening section can, for example, be tapered toward the sacrificial layer. This can mean, for example, that in a typical fastening situation, the fastening section has its greatest extent within the vessel and a smaller section extends outside the vessel wall. This can achieve particularly high stability within the vessel. However, the reverse design is also possible.

[0037] According to one embodiment, the fastening device is designed as an element that can be demarcated from the carrier medium. This can mean, in particular, that the carrier medium can be visually demarcated from the fastening device. For example, the carrier medium can have a different, in particular significantly different, cross-section than the fastening device and / or be made of a different, in particular visibly different, material. For example, the fastening device can be designed as a rod protruding from the carrier medium.

[0038] The fastening device can, in particular, be entirely or partially tubular. This corresponds to a simple and stable design.

[0039] The carrier medium can, in particular, have a receptacle for inserting a bolt for fastening to the vessel wall. The receptacle can, for example, be designed as a cavity within the carrier medium that is open on at least one side or exactly one side. Such a receptacle can, for example, be considered a fastening device. The bolt can, in particular, be fastened to the vessel wall, preferably to a web of the vessel wall. Thus, the probe can be fastened to the vessel wall, for example, by slipping it onto the bolt.

[0040] According to one embodiment, the sacrificial layer consists entirely of the sacrificial material. In other words, in this case, the sacrificial layer is identical to the sacrificial material. However, the sacrificial layer can also contain additional components that can, for example, improve heat transfer or influence the behavior of the sacrificial material.

[0041] The carrier medium can be made of metal, iron, or ferrochrome, depending on the respective embodiments. The carrier medium can also be made of steel, nickel-chrome steel, or a nickel-based alloy, depending on the respective embodiments. A steel or alloy can, in particular, be highly alloyed. In particular, the mass fraction of at least one alloying element can thus be at least 5%. The carrier medium can also be made of ceramic or graphite. These materials have proven advantageous due to their heat and corrosion resistance and / or corrosion resistance. For example, a steel known as Inconel can be used for the carrier medium. In particular, a steel known as Alloy 625 or under material number 2.4856 can be used. These materials can also be combined with one another and / or with other materials.

[0042] The carrier medium can, in particular, have a plurality of pores, with the sacrificial layer being contained entirely or partially within the pores. This allows for a particularly large surface area for the sacrificial layer, which allows for particularly good measurement of the sulfation performance. For example, the carrier medium can be designed as a porous body, in particular as a porous ceramic body. This allows for a large number of pores and a correspondingly large surface area to be realized. Preferably, all or at least the majority of the pores should have a gas-permeable connection to the environment of the probe.

[0043] According to one embodiment, the carrier medium can have a porous region in which the pores, or at least some of the pores, are arranged. This porous region can, in particular, be arranged on the outside of the carrier medium. The pores can, in particular, all or at least partially, preferably predominantly, be fluidically connected to the environment of the carrier medium, so that flue gas surrounding the probe can penetrate into the pores. A porous region can, for example, be sponge-like.

[0044] According to advantageous embodiments, some or all of the pores may have a diameter of at least 50 µm, at least 100 µm, or at least 150 µm. According to advantageous embodiments, some or all of the pores may have a diameter of at most 150 µm, at most 200 µm, or at most 300 µm. Such diameters have proven advantageous for typical applications because they allow for the deposition of a sacrificial material within the pores and facilitate good gas exchange between the pores.

[0045] According to advantageous embodiments, the sacrificial layer can have a thickness of at least 5 µm, at least 10 µm, or at least 15 µm, entirely or partially. According to advantageous embodiments, the sacrificial layer can have a thickness of at most 15 µm, at most 20 µm, or at most 30 µm, entirely or partially. Such thicknesses or thickness ranges have proven advantageous. For example, such a thickness can enable sulfation of the sacrificial layer by flowing flue gas without shielding deeper areas. The available sacrificial material can thus be ideally utilized.

[0046] The thickness of the sacrificial layer can be, for example, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 20 µm, 25 µm or 30 µm. It can also be selected from an interval whose lower limit is 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 15 µm, 20 µm or 25 µm and whose upper limit is 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 20 µm, 25 µm or 30 µm. Any specified lower limit can be combined with any larger specified upper limit to form an interval. Such layer thicknesses have been found to be advantageous.

[0047] According to one embodiment, the sacrificial layer can be formed by fully or partially immersing the carrier medium in a saturated halogen salt solution. This enables simple production and reliable coverage of the relevant surface with the sacrificial layer. Alternatively, the halogen salt solution can also be unsaturated, for example. Other production methods can also be used; for example, the sacrificial material can be pressed, for example, in tablet form, or the sacrificial material can be applied by coating processes and / or secured with a holder.

[0048] The carrier medium and / or the fastening device can advantageously be formed by 3D printing. The use of 3D printing for production allows for particularly high variability. In particular, the aforementioned pores can also be formed by 3D printing. This allows for simple, precise, and reproducible formation of the pores.

[0049] According to an advantageous embodiment, the probe can have a cavity with an inlet for air or another medium for cooling or tempering the probe. This allows the probe to be actively cooled. This allows the sacrificial layer to be cooled, for example, to a temperature below the flue gas temperature, thus preventing sublimation or other thermal damage to the sacrificial layer, which would distort the measurement.

[0050] According to an advantageous embodiment, the probe has a shading unit that at least partially surrounds the sacrificial layer. This allows incoming flue gas to be shielded from the probe. The shading device can be designed in particular as a plate or curved element, for example a cylinder-segment-shaped element. The flue gas can then flow past the shading unit, for example, and flow to the probe via a path that includes a change in direction. Such a change in direction can occur, for example, at an edge of the shading unit. The shading unit thus ensures that the probe is not directly exposed to the flue gas, but indirectly, whereby the kinetic energy of the flue gas impinging on the probe is significantly lower. Damage to the sacrificial layer due to mechanical impact can thus be avoided.In addition, significantly fewer fly ash particles or other particles entrained in the flue gas can impact the sacrificial layer. Such particles can lead to the formation of an incrustation or other layer that shields the sacrificial layer.

[0051] It should be noted that the probe can, for example, be passively cooled, which occurs particularly due to the inevitable heat transfer from the probe to the vessel wall or through contact with the vessel wall. However, active cooling can also be provided in the probe, for example, by providing a channel for introducing air or another fluid, whereby such a fluid can be used for cooling or generally for temperature control. This allows a defined temperature to be set. This temperature can be monitored, for example, using the thermocouple mentioned above.

[0052] Further described herein is a boiler assembly. The boiler assembly has a boiler wall enclosing a boiler. The boiler assembly further includes a probe as described herein, which is attached to the boiler wall. All designs and variants described herein may be used for the probe.

[0053] It should be noted that the probe can be used, for example, in a combustion chamber. A combustion chamber refers specifically to a part of the boiler, for example, the first pass in a grate furnace. However, the probe can also be used in other parts of the boiler. The term "boiler" can be generalized as a flue gas system. The boiler arrangement can thus also be referred to as the arrangement of a flue gas system.

[0054] The boiler arrangement can be used to determine the sulfation performance at a specific location using the probe. For example, the boiler arrangement may contain a device for the targeted production of sulfur trioxide (SO3), which can be evaluated and optimized using the probe.

[0055] Preferably, several probes are provided on the boiler wall so that the sulfation performance can be determined depending on a specific position. This allows for a spatially resolved determination of the sulfation performance at different locations in the boiler.

[0056] The vessel wall may have at least one hole through which a protruding pin of the probe or a probe mounting device is passed. This allows the probe to be attached easily and reliably, although other mounting options are also conceivable.

[0057] The pin can, in particular, seal the hole, thereby easily preventing flue gas from escaping through the hole. The pin can, in particular, be held in the hole by means of a retainer. This allows for easy attachment. The retainer can, for example, be wedge-shaped or a wedge, or it can be screwed to the pin on the outside, i.e., outside the boiler.

[0058] The hole can be formed, in particular, in a web between two tubes of a heat exchanger formed in the boiler wall or in a boiler wall functioning as a heat exchanger. Such a web can, in particular, be part of the boiler wall or the heat exchanger. In certain designs, such webs already have various holes, which can be used, for example, for attaching heat insulation panels. Such a hole can now be easily used for a probe. This has the particular advantage that the sulfation performance can be measured easily at a location where the sulfation performance is actually needed.

[0059] However, instead of a hole in a web, a measurement port, inspection port, or manhole in a boiler wall can also be used. These can be larger openings, for example, designed for inspection purposes, including allowing access for personnel. For this purpose, for example, the tubes of a heat exchanger can be bent in such a way that the opening can be formed between them.

[0060] A hole can have a round cross-section, but can also have a different cross-section such as a rectangular or square cross-section.

[0061] The probe can be used preferably in the area of ​​a cladded or unprotected membrane wall.

[0062] The pin can, in particular, be conical, with it tapering towards one end. This can simplify insertion of the pin and sealing of a hole.

[0063] According to one design, a bolt protrudes from the boiler wall and conveniently engages a probe mount. This allows for easy attachment of the probe by simply slipping it onto the bolt. Please refer to the relevant explanations above.

[0064] According to one embodiment, the boiler assembly may include a temperature control device for cooling or tempering the probe. Such a temperature control device may, in particular, be located outside the boiler. Typically, it does not come into direct contact with the flue gas.

[0065] The temperature control device can be designed, in particular, to supply air or another medium to the probe. For example, the temperature control device can be designed to provide appropriately tempered, for example, cooled, air or another tempered medium. For this purpose, the temperature control device can be designed, for example, as a heat exchanger. It can, for example, be thermally connected to a reservoir for dissipating heat.

[0066] According to one embodiment, the probe can have a shading device or shading unit that at least partially shades the sacrificial layer from incoming flue gas. Complete shading is also possible. The shading device can be designed, in particular, as a plate or curved element, for example, a cylindrical segment-shaped element. This prevents incoming flue gas from directly impinging on the probe. Reference is made to the relevant explanations above.

[0067] The boiler wall can, in particular, define a plurality of boiler passes. Such passes can be defined, for example, by different temperature ranges and / or different profiles or cross-sectional areas. One or more probes can be arranged in each pass, or in at least some passes. Thus, the respective sulfation performance can be determined in different passes, which allows particularly accurate conclusions to be drawn about the sulfation performance and the effectiveness of any devices for generating sulfur trioxide.

[0068] The invention relates to a method for determining a sulfation performance in a flue gas, the method comprising the following steps: Introducing a probe as described herein into the flue gas, leaving the probe in the flue gas for a predetermined period of time, determining a change in the sacrificial layer, and determining the sulfation performance based on the change.

[0069] This makes it easy to determine sulfation performance using the probe described above as intended. All versions and variants of the probe described herein can be used.

[0070] The change may in particular be a chemical reaction during operation.

[0071] The predetermined period of time may, for example, lie in an interval whose lower limit is one minute, two minutes, five minutes, ten minutes, thirty minutes, one hour, two hours, three hours, four hours, five hours, 10 hours, one day, two days, three days, four days, five days, ten days, two weeks, or three weeks, and whose upper limit is two minutes, five minutes, ten minutes, thirty minutes, one hour, two hours, three hours, four hours, five hours, ten hours, one day, two days, three days, four days, five days, ten days, two weeks, three weeks, or four weeks. Any specified lower limit may be combined with any larger specified upper limit to form an interval. Such times have proven reasonable for determining sulfation performance at typical sulfation performances. In particular, the period may range from a few minutes to a few hours.However, other periods are also possible.

[0072] Before determining a change in the sacrificial layer, the probe can be removed from the flue gas, for example, from a boiler through which the flue gas is conducted. The change is best determined only after the predetermined period has elapsed.

[0073] The method can be carried out in particular in a boiler arrangement described herein. Regarding the boiler arrangement, all designs and variants described herein can be used.

[0074] When determining a change in the sacrificial layer, it is possible, in particular, to determine the amount of halogen salt and / or cations contained in the halogen salt that are still present in the flue gas after the probe has been left in place. This amount can, in particular, be compared with the amount of halogen salt and / or cations contained in the halogen salt in the sacrificial layer before the probe is introduced into the flue gas. This makes it possible to determine how much of the originally present halogen salt is still present in the flue gas after the sample has been left in place. The less of the originally present halogen salt is still present at the end, the higher the sulfation performance is typically. The halogen salt is considered a combination of cations and anions, with the cation typically being retained in the reaction, as already mentioned. For example, originally present strontium chloride can be converted into strontium sulfate.

[0075] In particular, a halogen salt soluble in a solvent, for example, water, can be used as the sacrificial material. The amount of halogen salt and / or cations contained in the halogen salt still present in the flue gas after the probe has been left in place can be determined, in particular, by dissolving the sacrificial layer in the solvent.

[0076] Such dissolution allows for particularly simple process control. For example, the amount of halogen salt still present and / or cations contained in the halogen salt or an amount of halogen salt dissolved in the solvent and / or cations contained in the halogen salt can be determined using wet chemical or spectroscopic methods. Titration can be used for this purpose, for example. Such methods can typically also be carried out on-site, i.e. in the premises of power plants or waste incineration plants, using simple means. This avoids the need for a probe to first have to be taken to a laboratory for analysis. In particular, after dissolution, an amount of the cation or cations of the halogen salt can be determined. This provides an indication of the amount of halogen salt actually present and is typically the quantity of interest.

[0077] However, it should be understood that the amount of halogen salt and / or cations contained in the halogen salt can also be determined in other ways after leaving the probe in the flue gas, for example by visual observation, measuring a change in weight or by scraping off existing components of the sacrificial layer.

[0078] When determining a change in the sacrificial layer, it is possible to determine, in particular, the amount of sulfate and / or cations contained in the sulfate present in the sacrificial layer after the probe has been left in the flue gas. This sulfate was formed from the halogen salt by reaction with sulfur trioxide and thus also serves as an indicator of the sulfation efficiency. The more sulfate formed in a given period of time, the higher the sulfation efficiency.

[0079] The amount of sulfate and / or cations contained in the sulfate can be determined, in particular, by dissolving the sacrificial layer in another solvent. Typically, a solvent in which the sulfate is highly soluble is used. For example, hydrochloric acid, aqua regia, nitric acid, sulfuric acid, hydrofluoric acid, or another strong acid can be used. Additionally, mechanical pressure can be applied and / or mechanical comminution methods can be used to achieve a good solution.

[0080] The sacrificial layer is preferably dissolved in the additional solvent only after the halogen salt has been removed from the sacrificial layer, for example, by dissolving it in the solvent in which the halogen salt is soluble, as described above. This prevents falsification of the measurement results.

[0081] In particular, sequential elution can thus be carried out. The sacrificial layer can, for example, first be dissolved in water or another solvent, in which case the amount of dissolved halogen salt and / or cations contained in the halogen salt is then determined. The remaining portion can then be dissolved in hydrochloric acid or another solvent, in which case the amount of sulfate dissolved in the solvent and / or cations contained in the sulfate is then determined. The latter can also be carried out, for example, using wet-chemical or spectroscopic methods, e.g., titration. Sulfate here refers in particular to the complete salt, i.e., including cations and anions. It should be noted that the amount of anions is typically not of interest here, but rather the amount of cations present. In particular, the sulfate formed from the sacrificial material by reaction is therefore considered.

[0082] Advantageously, a sum can be formed from the amount of one or more types of cations or alkaline earth metals in the halogen salt that is still present in the flue gas after the probe has been left in the flue gas, and in the sulfate that is present in the sacrificial layer after the probe has been left in the flue gas. In other words, it is determined, for example, which amount of one or more types of cations or alkaline earth metals is still present in the halogen salt after it has remained in the flue gas and which amount of that type or types of cations or alkaline earth metals is present in the sulfate that was formed while it remained in the flue gas. This sum can, in particular, be compared with an amount of that type or types of cations or alkaline earth metals in the sacrificial layer before the probe is introduced into the flue gas. With ideal process implementation, both values ​​should be equal.A deviation may indicate that such cations or alkaline earth metals have been deposited from the flue gas or have been released into the flue gas.

[0083] According to one embodiment, the probe is cooled while immersed in the flue gas. The probe can be cooled, in particular, by blowing in air. Water can also be used for cooling. This can prevent thermal damage to the sacrificial layer, for example, through sublimation.

[0084] Advantageously, the probe can be cooled in the flue gas to a maximum temperature of 700 °C, 600 °C, or 500 °C. This has proven useful for typical materials to prevent thermal damage.

[0085] Further features and advantages will become apparent to those skilled in the art from the exemplary embodiments described below with reference to the accompanying drawings. These show: Fig. 1 : a probe according to a first embodiment, Fig. 2 : a probe according to a second embodiment, Fig. 3 : a probe according to a third embodiment, Fig. 4 : a boiler arrangement according to a first embodiment, Fig. 5 : a boiler arrangement according to a second embodiment, Fig. 6 : a boiler arrangement according to a third embodiment, and Fig. 7 : a boiler arrangement according to a fourth embodiment.

[0086] The method according to the invention can be advantageously carried out with the described probes and vessel arrangements.

[0087] Fig. 1 shows a schematic diagram of a probe 10 according to a first embodiment. This has a particularly simple design.

[0088] The probe 10 has a carrier medium 20, which in this case is made of chrome-nickel steel. A fastening device 30 is arranged on the probe 10, which in this case is designed as a simple pin 31. This pin 31 can, for example, be inserted into a hole in a boiler wall to fasten the probe 10 there, in particular such that the probe 10 is arranged inside the boiler.

[0089] A sacrificial layer 40 is formed on the outside of the carrier medium 20. In this case, the sacrificial layer 40 is identical to a sacrificial material, which is a halogen salt. For example, strontium chloride or barium chloride, or a combination of different halogen salts, can be used.

[0090] The probe 10 can simply be introduced into a flue gas, in particular into a boiler conducting such a flue gas, and can be left there for a predefined time. This directly exposes the sacrificial layer 40 to the flue gas. The amount of sacrificial material prior to introduction into the flue gas is known from the manufacturing conditions. After a predetermined time, the probe 10 can be removed from the flue gas, and the remaining amount of sacrificial material can be determined. For this purpose, the halogen salt can be dissolved, for example, in a solvent such as water, and the remaining amount can be determined using wet chemistry or spectroscopic methods. However, other evaluation methods are also possible.

[0091] Fig. 2 shows a probe 10 according to a second embodiment. This is constructed similarly to the first embodiment, but the carrier medium 20 is hollow on the inside, creating a cavity 25. A nozzle 50 opens into the cavity 25, and the cavity 25 also has an outlet opening 27. This makes it possible to blow air or another fluid into the cavity 25 via the nozzle 50, and the fluid can exit again via the outlet opening 27. This enables targeted cooling or general temperature control of the probe 10, so that, for example, a predetermined temperature can be specifically set. It can also be ensured that a temperature at which the sacrificial material would evaporate due to the temperature alone is not exceeded.

[0092] For measuring the temperature, the probe 10 according to the second embodiment further comprises a thermocouple 60. This allows the temperature of the probe 10 to be monitored and, if necessary, measures can be initiated to achieve the desired temperature. For example, cooling can be activated if a predetermined maximum temperature is about to be exceeded.

[0093] Fig. 3 shows a probe 10 according to a third exemplary embodiment. The carrier medium 20 is porous, so that a plurality of pores 22 are formed therein. The sacrificial layer 40 with the sacrificial material contained therein is located in the pores 22, wherein the sacrificial layer 40 in particular covers the respective walls of the pores 22. This ensures that a particularly large surface area is available, which is covered with the sacrificial layer 40. This allows for a particularly advantageous and reliable determination of the sulfation performance. The flue gas flows through the pores 22.

[0094] Furthermore, when executing according to Fig. 3 The pin 31 of the fastening device 30 is conical, tapering to the right. This can be advantageous for sealing a hole in which the fastening device 30 is to be attached.

[0095] It should be understood that the respective features of the embodiments can be combined with one another as desired.

[0096] Fig. 4 shows a section of a boiler assembly 1 according to a first exemplary embodiment. The boiler assembly 1 has a boiler wall 100, which surrounds a boiler not otherwise shown.

[0097] In the boiler wall 100, two schematically and only partially shown tubes 110 are formed, which can be part of a heat exchanger, for example. The view in Fig. 4 is viewed from the inside of the boiler onto the boiler wall 100. Between the two tubes 110, a web 120 is formed which connects the two tubes 110.

[0098] A hole 125 is formed in the web 120, which serves for fastening a probe 10 (also shown). The probe 10 passes through the hole 125 with its fastening device 30. The fastening device 30, designed as a pin 31, has a penetration section 35 located within the hole 125.

[0099] In the illustrated embodiment, the fastening device 30 has a conical elongated hole 37 on the outside. A counterholder in the form of a wedge 38 is passed through this hole, allowing the probe 10 to be clamped and secured. This enables simple and reliable fastening of the probe 10 and also easy removal, since the wedge 38 is located outside of a flue gas atmosphere and thus does not corrode. This design also allows the hole 125 to be sealed, preventing flue gas from escaping.

[0100] The probe 10 is positioned on the boiler wall 100 such that the flue gas flows around the sacrificial layer 40 and is therefore exposed to the flue gas's sulfation effect. This enables reliable determination and evaluation of the sulfation effect.

[0101] Fig. 5 shows a section of a boiler arrangement 1 according to a second embodiment.

[0102] In this case, a probe 10 is attached to a web 120, although the probe 10 is designed differently than in previous versions. The probe 10 has a porous region 24 in which a plurality of pores are formed. The pores are no longer individually labeled or illustrated. Rather, it is a sponge-like region, with the sacrificial layer located both on its outer surface and in the respective pores. The pores are fluidically connected to one another, allowing flue gas to penetrate the pores. This results in a significantly larger surface area of ​​the sacrificial layer at which the flue gas can attack the sacrificial layer.

[0103] In this case, the carrier medium 20 is formed integrally with a fastening section 32, which forms a fastening device 30. As shown, the fastening section 32 is provided with a conical outer cross-section. Its cross-sectional area decreases toward the porous region 24. The hole 125 in the web 120 is also conical and complementary to the fastening section 32. The fastening section 32 thus seals the hole 125, preventing flue gas from escaping. As an alternative to the hole 125 formed in the web 120, an inspection opening or a manhole in a boiler wall could also be used.

[0104] On the outside, i.e. opposite the flue gas area and in Fig. 5 On the right side, the probe 10 is held by a retaining plate 126, which in turn is attached to the web 120 with a first screw 127 and a second screw 128. The probe 10 is thus pressed into the hole 125. This type of attachment is very simple to implement and also easy to remove. By loosening the screws 127, 128, the probe 10 can be removed from the outside. This does not require entering the boiler.

[0105] Fig. 6 shows a detail of a boiler assembly 1 according to a third exemplary embodiment. A probe 10 is used, the fastening device 30 of which is tubular. The fastening device 30 is accommodated in the web 120.

[0106] On in Fig. 6 The sacrificial layer 40 is applied to the outside of the right-hand end. A cavity 25 is formed within the probe 10. A first channel 70 and a second channel 75 lead to this cavity. The first channel 70 is connected to a temperature control device 5. This device is designed to introduce cool air into the first channel 70. The cool air passes through the first channel 70 into the cavity 25 and cools the probe 10 directly beneath the sacrificial layer 40. This layer is thereby cooled to a temperature below the flue gas temperature. The air can escape from the probe 10 again through the second channel 75.

[0107] At the Fig. 6 The illustrated embodiment also includes a shading unit 80, which partially shields the probe 10 from incoming flue gas. This prevents overloading or damage to the probe 10 from directly impinging flue gas particles. The probe 10 is indirectly exposed to the flue gas, allowing it to continue to be in contact with the flue gas and achieve the desired function. The shading unit 80 can also be used in other embodiments.

[0108] It should be noted that, for example, a porous material can be applied to the carrier medium 20, and the sacrificial layer 40 can be contained therein. Reference is made to the description of a design with pores given elsewhere. Fig. 6 The area designated by reference numeral 40 can therefore be, for example, a porous material, for example a sponge-like material, with an incorporated sacrificial layer.

[0109] Fig. 7 shows a section of a boiler arrangement 1 according to a fourth embodiment. A probe 10 is used, in whose carrier medium 20 a receptacle 23 is formed. A bolt 105 engages in this receptacle 23, which is directly attached to the web 120. A sacrificial layer 40 is applied on the outside. Instead of a bolt 105, a carrier could alternatively be used, which can, for example, create a greater distance from the web 120 or, more generally, from the boiler wall 100. Even in the case of the embodiment of Fig. 7 a porous material can be used in which the sacrificial layer 40 is contained.

[0110] Such a design allows the probe 10 to be easily placed on an existing bolt 105. Such a bolt 105 can, for example, be welded to the web 120 or otherwise secured. Attaching and removing the probe 10 can be performed, in particular, during an inspection, during which a boiler is accessible from the inside.

Claims

1. Method for determining a sulfation power in a flue gas, wherein the method comprises the steps of: - introducing a probe (10) into the flue gas, wherein the probe (10) comprises the following: - a carrier medium (20) which is securable to a vessel wall (100) and - a sacrificial layer (40) which is arranged on the outside of the carrier medium (20) and which contains a sacrificial material composed of a halogen salt, - leaving the probe (10) in the flue gas for a predetermined period, - determining a change in the sacrificial layer (40) and - determining the sulfation power based on the change.

2. Method according to Claim 1, - wherein the halogen salt is strontium chloride or barium chloride.

3. Method according to either of Claims 1 or 2, - wherein the sacrificial layer (40) is composed entirely of the sacrificial material.

4. Method according to any of the preceding Claims, - wherein the method is performed in a vessel assembly (1) which comprises the following: - a vessel wall (100) which encloses a vessel and - the probe (10) which is secured to the vessel wall (100) .

5. Method according to any of the preceding Claims, - wherein determining a change in the sacrificial layer (40) comprises determining an amount of halogen salt and / or of cations present in the halogen salt which remains present after leaving the probe (10) in the flue gas.

6. Method according to Claim 5, - wherein the amount of halogen salt and / or of cations present in the halogen salt which remains present after leaving the probe (10) in the flue gas is compared with an amount of halogen salt and / or of cations present in the halogen salt in the sacrificial layer (40) before introducing the probe (10) into the flue gas.

7. Method according to either of Claims 5 or 6, - wherein a halogen salt soluble in a solvent is used as sacrificial material and - wherein the amount of halogen salt and / or of cations present in the halogen salt which remains present after leaving the probe (10) in the flue gas is determined by dissolving the sacrificial layer (40) in the solvent.

8. Method according to Claim 7, - wherein an amount of halogen salt and / or of cations present in the halogen salt dissolved in the solvent is determined spectroscopically or by titration.

9. Method according to any of the preceding Claims, - wherein determining a change in the sacrificial layer (40) comprises determining an amount of sulfate and / or of cations present in the sulfate which remains present in the sacrificial layer (40) after leaving the probe (10) in the flue gas.

10. Method according to Claim 9, - wherein the amount of sulfate and / or of cations present in the sulfate is determined by dissolving the sacrificial layer (40) in a further solvent.

11. Method according to Claim 10, - wherein the sacrificial layer (40) is only dissolved in the further solvent once halogen salt has been removed from the sacrificial layer (40).

12. Method according to any of the preceding Claims, - wherein a sum is formed from the amount of one or more types of cations or alkaline earth metals in the halogen salt which remains present after leaving the probe (10) in the flue gas and in the sulfate which is present in the sacrificial layer (40) after leaving the probe (10) in the flue gas and - wherein this sum is compared with an amount of the type or the types of cations or alkaline earth metals in the sacrificial layer (40) before introducing the probe (10) into the flue gas.

13. Method according to any of the preceding Claims, - wherein the probe (10) is cooled while it is in the flue gas.

14. Method according to Claim 13, - wherein the probe (10) is cooled by injection of air.

15. Method according to either of Claims 13 or 14, - wherein the probe (10) in the flue gas is cooled to a temperature of at most 700°C, at most 600°C or at most 500°C.