WO2022214172A1

WO2022214172A1 - A rotary atomizer

Info

Publication number: WO2022214172A1
Application number: PCT/EP2021/059067
Authority: WO
Inventors: Roland VAN SILFHOUT; Lisa RABENOW; Asger Jørgen Thor HANSEN; Tine GREIBE
Original assignee: Gea Process Engineering A/S
Priority date: 2021-04-07
Filing date: 2021-04-07
Publication date: 2022-10-13
Also published as: CN117157152A; EP4319923A1

Abstract

The present invention relates to a rotary atomizer for a spray drying apparatus. The rotary atomizer comprises a protective member surrounding an inner volume of the rotary atomizer, the protective member having an inlet end and an outlet end; a feed inlet in fluid communication with an atomizer wheel at the outlet end; wherein the protective member is made from a material comprising a fibre-reinforced polymer of a woven or non-woven mat of glass or carbon filaments in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C. The rotary atomizer is especially suited for spray dryers functioning in corrosive environments, in particular spray drying absorption (SDA), and the invention also relates to a spray dryer absorber.

Description

A rotary atomizer

Field of the invention

The present invention relates to a rotary atomizer for a spray drying apparatus. The rotary atomizer comprises a protective member to protect electronic and mechanical components of the rotary atomizer, and the rotary atomizer is especially suited for spray dryers functioning in corrosive environments, in particular spray drying absorption (SDA).

Prior art

Spray dryers are used to produce powdery products from a liquid feed, and in a spray dryer a liquid feed material is transformed into a dried particulate form by spraying the feed material into a hot drying medium. A spray dryer generally comprises an atomizer that distributes the liquid feed into appropriately sizes droplets so that the hot drying medium can evaporate the moisture from the liquid droplets and provide the desired powder. The atomizer is typically located in the top section of the drying chamber and the hot drying medium enters the drying chamber in the bottom section of the drying chamber so that the droplets of the liquid feed will be transformed to a dry powder when falling down in the drying chamber.

Spray drying is used in the manufacture of various powdery products from dairy-, chemical-, or pharmaceutical-based feed liquids, although other uses involve more corrosive environments thus requiring more attention to protection of the internal components of the feed distributor. A specific spray drying process is known as spray drying absorption (SDA), and the corresponding spray dryer is, in the context of the present disclosure, referred to as a “spray dryer absorber”. In spray drying absorption, a flue gas is introduced into the spray drying apparatus in the top section so that the flue gas will meet the liquid feed droplets. The composition of the feed liquid is selected to absorb gaseous components, in particular pollutants, of the flue gas thereby removing the gaseous components from the flue gas. For example, lime, e.g. CaO or Ca(OH)₂, can be used as an absorbent in spray drying absorption to remove pollutants, such as SO2, SO3, HCI, Hg, and dioxins, from flue gasses from fossil fuel power plants or waste incinerators. A spray drying absorption process can be designed to remove specific pollutants from specific flue gasses by selection of appropriate absorbents, but in general flue gasses are highly corrosive.

The atomizer of a spray dryer is part of the feed distributor, which thus contains conduits for leading the liquid feed from a supply to the atomizer, mechanical parts and electronic components as appropriate to control the feed supply and atomization. The feed distributor of a spray dryer normally comprises a skirt surrounding the internal components of the feed distributor to shield the internal components from the environment, and for a spray dryer absorber the shielding is especially relevant. For example, CN206715667U discloses a spray dryer absorber with a special design of a rotary atomizer and a skirt to protect the atomizer wheel from harmful effects of flue gas.

The skirt in a spray dryer absorber is traditionally made of metal with at least the section near the atomizer wheel being made from high-nickel alloys, e.g. alloys also known as Hastelloys. High-nickel alloys are resistant to corrosion from the flue gas, but even though the alloys are corrosion resistant, the respective components, in particular the whole skirt, must be replaced regularly, e.g. after two to eight years of operation. Moreover, nickel is very expensive, and it is therefore desirable to provide a cheaper material for the skirt.

A spray dryer skirt made from a combination of stainless steel and a high-nickel alloy may also be coated with the high-nickel alloy on the stainless steel part and the weld or joint between the stainless steel part and the high- nickel alloy. These coatings are however more fragile and tend to wear and crack.

The present invention aims to provide a skirt for a spray dryer absorber that is sufficiently resistant to corrosion from a flue gas, but which is available at a lower price than a skirt based on a high-nickel alloy or coatings. Disclosure of the invention

The present invention relates to a rotary atomizer for a spray drying apparatus, the rotary atomizer comprising: a protective member surrounding an inner volume of the rotary atomizer, the protective member having an inlet end and an outlet end, and a feed inlet in fluid communication with an atomizer wheel at the outlet end, wherein the protective member is made from a material comprising a fibre-reinforced polymer of a woven or non-woven mat of glass or carbon filaments in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C.

The rotary atomizer is suitable for a spray drying apparatus, in particular for a spray drying process known as spray drying absorption (SDA), and the spray drying apparatus may also be referred to as a spray dryer absorber. Thus, the rotary atomizer may be a rotary atomizer for a spray dryer absorber. In a conventional spray dryer, the liquid feed is introduced into a drying chamber. In a spray dryer absorber, the liquid feed is likewise introduced into a chamber, and in the present context the chamber is referred to as an “absorption chamber”.

The present rotary atomizer comprises a feed inlet at an inlet end, which feed inlet is in fluid communication with an atomizer wheel at the outlet end. In general, the feed inlet is provided with a liquid feed from a supply, e.g. a supply external to the rotary atomizer, and the rotary atomizer has a conduit or the like to provide the liquid feed to the atomizer wheel. The atomizer wheel may have any design typically used in spray dryers. Exemplary spray dryer absorber, which include rotary atomizers, are marketed by GEA Process Engineering A/S, Soborg, Denmark, e.g. spray dryer absorbers known under the names of F01A, F100, and F160. The present rotary atomizer may comprise any component used in rotary atomizer of presently available spray dryer absorbers.

The rotary atomizer may comprise any component for controlling the atomisation of the liquid feed. For example, the rotary atomizer may comprise additional conduits or pipes for additional fluids or liquids, motors, pumps and/or actuators for moving components and/or fluids, cables for supplying electricity to electric and electronic components, and electric and electronic components. Collectively, such components are referred to as “inner parts” in the context of the disclosure. Typically, the inner parts are contained in the inner volume of the rotary atomizer.

The spray drying absorption may be any spray drying absorption process known in the art, but the spray drying absorption process typically involves removal of pollutants from a flue gas by absorbing the pollutants to an absorbent. In the context of the disclosure, the flue gas may be any gas containing pollutants that can be sequestered from the flue gas by an absorbent contained in the liquid feed. Exemplary flue gasses are from power plants, e.g. power plants burning fossil fuels, such as coal, wood chips, biomass, etc., metal and mineral processing plants, e.g. steel plants, waste incinerator plants, e.g. plants for burning hazardous waste.

The pollutants may be any compound that is not acceptable in the environment so that it must be removed from the flue gas. The pollutants are typically gaseous compounds or elements, although particulate pollutants are also contemplated. Exemplary pollutants include SO2, SO3, HCI, HF, and similar compounds, and also dioxins and Hg. Certain pollutants can be absorbed as particles of salts of calcium, e.g. CaC , CaF2, CaSC , CaSC , and the feed liquid may comprise CaO and/or Ca(OFI)2 as absorbents. Activated carbon may also be included as an absorbent, e.g. in the liquid feed and/or as an additive to the flue gas in order to remove other pollutants, e.g. Fig, and dioxins. Flowever, the absorbent is not limited to CaO or Ca(OFI)2 and other absorbents are known within the art.

Pollutants such as SO2, SO3, HCI, and HF are acidic and provide a strongly corrosive environment. A flue gas is typically introduced into a spray dryer absorber at an increased temperature, e.g. in the range of 200°C to 400°C. For example, the flue gas may be led to the spray dryer absorber without any active cooling of the flue gas from the source of the flue gas, e.g. a furnace or the like, that burns the material providing the flue gas. The increased temperature is advantageous in the adsorption process, but the increased temperature also increases the reaction rate of corrosive processes created by the pollutants in the flue gas.

In addition to the flue gas with corrosive pollutants, the SDA process also uses a feed liquid, e.g. a solution or suspension of CaO and/or Ca(OH)2, which upon reaction with the pollutants forms particles that are subsequently dried in the spray dryer absorber. In the present context, a feed liquid may also be referred to as an absorbent liquid, and the two terms may be used interchangeably. The feed liquid is distributed into the absorption chamber as microdroplets from the rotary atomizer, and once the microdroplets are brought into contact with the flue gas, particles, e.g. of CaC , CaF2, CaSC , CaSC , etc., of sizes corresponding to the sizes of the microdroplets, i.e. in the micrometre range, form. During the SDA process the micrometre sized particles will coagulate into particles of larger size that can be collected as a product, but the micrometre sized particles provide an extremely abrasive environment. The atomizer wheel of the rotary atomizer introduces the microdroplets of the adsorbent liquid in a rotary pattern, which is immediately brought into contact with the flue gas. Therefore, the rotary atomizer is surrounded by a vortex of flue gas with corrosive pollutants, microdroplets of the absorbent liquid and microparticles formed by reaction between the absorbent and the pollutants. The vortex is rotated at a high velocity, which creates an abrasive environment from the absorbent liquid, and in particular microparticles formed by reaction between the absorbent and the pollutants. Materials of the rotary atomizer are exposed to the abrading effect of the abrasive environment, which can scratch the material thereby increasing the surface area of the material. The material of the rotary atomizer can thus have an increased surface area, which in turn will enhance the corrosive effect of the pollutants, especially considering the increased of at a temperature of at least 200°C. In the present context, the combined effect of the abrasive and corrosive environment is referred to as a degrading effect, and the combined effects may be referred to as degradation.

A rotary atomizer for a spray dryer absorber typically comprises moving parts, e.g. a motor, gear box, etc., and electrical and electronic components contained in the inner volume of the rotary atomizer, which must be shielded from the corrosive environment, and the rotary atomizer therefore normally comprises a protective member. The present rotary atomizer thus comprises a protective member. The protective member may have any shape as desired, but the protective member is preferably frustoconical or cylindrical. The protective member surrounds the inner volume of the rotary atomizer and thereby the inner parts of the rotary atomizer, to shield the inner parts from the flue gas, e.g. a vortex of the flue gas, the absorbents and the microparticles formed by reaction between the absorbent and the pollutants, so that contact between the pollutants, the absorbents and the microparticles, and the inner parts is avoided and the inner parts are protected from degradation from the pollutants, the absorbents and the microparticles.

Protective members of rotary atomizers for spray dryer absorbers are conventionally made, or at least partly made, from high-nickel alloys. In the present context, a high-nickel alloy is an alloy with at least 50 wt% nickel and alloying elements such as chromium, iron, cobalt, molybdenum, manganese, other metals, and optionally non-metallic elements to a total of 100%. Exemplary high-nickel alloys are marketed by Haynes International, Kokomo, Indiana, USA, under the trademark Hastelloy. High-nickel alloys are also known as superalloys. The high-nickel alloys are generally considered to provide the best resistance to the enhanced degrading environment existing in the vicinity of a rotary atomizer in a spray dryer absorber due to the combined effect of the abrasive particles and the corrosive pollutants at the increased temperature.

Fibre-reinforced polymer materials are commonly used for pipes and the like to transport flue gasses. Fibre-reinforced polymer materials comprise fibres of glass, carbon, or other materials, in a polymer resin, and for flue gas applications, the resin may be chosen based on its corrosion resistance. Fibre- reinforced polymer materials are both lighter and cheaper than Hastelloys and these characteristics are attractive for a material for a protective member, since a protective member of a fibre-reinforced polymer would be easier to handle during installation and service. However, the abrasive vortex in a spray dryer absorber is expected to wear the resin of a fibre-reinforced polymer material down, and thereby damage the integrity of the fibre-reinforced polymer material, faster than a Hastelloy is degraded, regardless of the chemical resistance of the resin of the fibre-reinforced polymer material otherwise appropriate for flue gas applications. The present inventors have now surprisingly found that when the protective member of a rotary atomizer of a spray dryer absorber is made from a material comprising a fibre-reinforced polymer of a woven or non-woven mat of glass or carbon filaments in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C, the protective member will last as long as a protective member made from a high-nickel alloy. Moreover, since the fibre- reinforced polymer is much cheaper than a high-nickel alloy, especially when the fibres are glass filaments, a cheaper protective member for a spray drying apparatus is provided, in particular for a spray dryer absorber. In general, the glass transition temperature should be as high as possible. For example, the glass transition temperature may be at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C or at least 200°C.

The resin matrix used in the manufacture has a glass transition temperature of at least 125°C. The resin matrix should preferably also be resistant to acid and oxidising conditions. The resins may for example be thermosetting resins of the epoxy-vinyl ester type, e.g. a resin based on ester of an epoxy with acrylic acid or methacrylic acid, and of the phenol- formaldehyde type. Exemplary epoxy-vinyl esters are Derakane and Derakane Momentum 470 resins as marketed by Ashland Inc., Covington, Kentucky, USA, e.g. Derakane 470HT-400 and Derakane Momentum 470-300. Exemplary phenol-formaldehyde resins are marketed by Hexion, Inc., Columbus, Ohio, USA, e.g. Cellobond. Further relevant resins are known to the skilled person.

The fibre part of the fibre-reinforced polymer may be any fibre commonly used in fibre-reinforced polymers. Flowever, the fibre should withstand increased temperatures of up to 300°C. For example, the fibre may be a glass fibre or a carbon fibre. The fibre-reinforced polymer may for example be a woven or non-woven mat of glass filaments in the resin matrix of the thermosetting or thermoplastic polymer. The woven or non-woven mat of glass filaments may be any mat known in the art, and the glass may be any glass commonly used in the art. For example, the glass filaments may be arranged in a random pattern in the mat, or the glass filaments may be ordered, e.g. the glass filaments may be arranged in a unidirectional pattern. It is also contemplated that individual strands of glass fibres are used to provide a mat shaped to provide the protective member.

It is further contemplated that other fibrous materials, e.g. carbon fibres, may replace the glass filaments, or that glass filaments and carbon fibres may be used in combination. In a further example, the protective member is made from a material comprising a fibre-reinforced polymer of a woven or non-woven mat of carbon fibres in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C, e.g. a glass transition temperature of at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C or at least 200°C. Likewise, the fibre-reinforced polymer may comprise a woven or non-woven mat of carbon fibres and glass filaments in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C, e.g. a glass transition temperature of at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170°C, at least 180°C, at least 190°C or at least 200°C.

A feed inlet is located at an inlet end of the protective member, and an atomizer wheel is located at an outlet end of the protective member. In an example, the protective member generally has the shape of a frustum, i.e. the protective member is a frustoconical protective member, and the inlet end is the wide end of the frustum, and the outlet end is the narrow end of the frustum. In another example, the protective member has a cylindrical shape. The distance between the inlet end and the outlet end of the protective member defines a length axis of the protective member, and likewise the dimension normal to the length axis of the protective member is a cross-sectional dimension in the context of the disclosure. The cross-sectional shape of the protective member may be chosen freely but is typically round or elliptical, e.g. the protective member is a frustoconical protective member or a cylindrical protective member. Conduits of the protective member are generally aligned with the length axis of the protective member. The rotary atomizer has an atomizer wheel at the outlet end, and the rotary atomizer has a conduit or the like to provide the liquid feed to the atomizer wheel. For example, a conduit may be located in the inner volume of the rotary atomizer. The atomizer wheel may be mounted as desired, in particular the atomizer wheel may be on the length axis of the protective member. For example, the conduit for the atomizer wheel may extend through an opening at the outlet end of a protective member, e.g. the narrow end of a frustoconical protective member. Flowever, it is also contemplated that the protective member may have a conical shape with one or more appropriate openings for a conduit or conduits near the tip of the conus for supplying the atomizer wheel with feed liquid.

When the protective member is a frustoconical protective member, the frustoconical protective member can be described to have a tip section from the narrow end of the frustoconical protective member and a bulk section from the wide end of the frustoconical protective member. Likewise, when the protective member is a cylindrical protective member, the cylindrical protective member can be described to have a tip section from the outlet end of the cylindrical protective member and a bulk section from the inlet end of the cylindrical protective member. In particular, the tip section is closest to the atomizer wheel at the outlet end, and therefore the abrasive and corrosive effects of the vortex surrounding the atomizer wheel are stronger near the tip. The tip section can thus constitute up to 15% of the total length of the protective member, such as up to 14%, up to 13%, up to 12%, up to 11 %, or up to 10% of the total length of the protective member, in particular a frustoconical protective member or a cylindrical protective member. It is, however, also contemplated that the tip section constitutes more than 15% of the total length of the protective member. For example, the tip section may constitute up to 20% of the total length of the protective member. A spray dryer absorber may have a flue gas inlet located for the flue gas to be introduced into the spray dryer absorber near, in particular adjacent to, the atomizer wheel in order to optimise contact between the flue gas and the atomized feed liquid with the absorbent and thereby optimise removal of pollutants from the flue gas. When the flue gas inlet is adjacent to the atomizer wheel, in particular when the protective member is a frustoconical protective member, the tip section is exposed more strongly to the pollutants and the accompanying corrosive effect of the pollutants and also the abrasive effect of the microparticles formed by reaction between the absorbent and the pollutants so that the tip section is affected more by the pollutants and abrasion than the bulk section of the protective member, e.g. the frustoconical protective member. Therefore, the tip section is degraded faster than the bulk section and therefore the tip section of the protective member of conventional spray dryer absorbers is made from a high-nickel alloy. However, for the present rotary atomizer a high-nickel alloy is not needed for the tip section, and it is preferred that the tip section does not comprise a high-nickel alloy, e.g. the tip section constituting up to 15% of the total length of the protective member from the outlet end of the protective member does not comprise a high-nickel alloy. In a specific example, the protective member is a frustoconical protective member, and the tip section constituting up to 15% of the total length of the frustoconical protective member from the narrow end of the frustoconical protective member does not comprise a high-nickel alloy.

The tip section, e.g. the tip section of a frustoconical protective member or a cylindrical protective member, may substantially consist of the fibre- reinforced polymer. When the tip section, e.g. the 15% of the total length of the protective member from the outlet end, substantially consists of the fibre- reinforced polymer, the remaining material, e.g. the 85% or more of the total length of the protective member from the inlet end, may consists of any appropriate material. For example, the 15% of the total length of the protective member from the outlet end may substantially consist of the fibre-reinforced polymer, and the remaining material of the protective member may consist of stainless steel. When the tip section of the protective member, e.g. the 15% of the total length of a frustoconical or cylindrical protective member, from the outlet end substantially consists of the fibre-reinforced polymer, a cheaper protective member is obtained than when a high-nickel alloy is used for the tip section without jeopardising the resistance to the enhanced degrading environment in a spray dryer absorber otherwise obtained using a high-nickel alloy. It is especially preferred that the protective member is a frustoconical protective member having a tip section not comprising a high-nickel alloy, e.g. having a tip section substantially consisting of the fibre-reinforced polymer, when the rotary atomizer is installed in a spray dryer absorber having a flue gas inlet located in a top section of the absorption chamber, in particular adjacent to the rotary atomizer.

In a specific example, the material of the protective member, e.g. a frustoconical protective member or a cylindrical protective member, substantially consists of the fibre-reinforced polymer. In particular, the material does not comprise a high-nickel alloy. In the present context, “substantially consists of means that the protective member, or the tip section of the protective member, is made from the fibre-reinforced polymer with necessary components for assembly of the rotary atomizer and/or for integration of the rotary atomizer with a spray drying apparatus, especially a spray dryer absorber, being made from any appropriate material. Likewise, when the tip section of the protective member substantially consists of the fibre-reinforced polymer, components for assembling the protective member, i.e. connecting the tip section and the bulk section, may be made from any appropriate material. In particular, any component used for the assembly of the tip section and the bulk section of the protective member, the rotary atomizer and/or for integration of the rotary atomizer with a spray drying apparatus can generally easily be replaced. For example, the protective member, e.g. a frustoconical protective member or a cylindrical protective member, may comprise a flange at the inlet end, e.g. the wide end, for mounting the protective member, and thereby the rotary atomizer, in a spray dryer absorber. The flange may comprise holes to be aligned with holes in the spray dryer absorber to mount the rotary atomizer using screw, bolts, or the like. In particular, the protective member, e.g. a frustoconical protective member or a cylindrical protective member, and the flange may be made as a single piece that is substantially made from the fibre-reinforced polymer. Likewise, the tip section may comprise holes aligned with holes in the bulk section for assembly of the tip section with the bulk section to provide the protective member using appropriate components. Exemplary components comprise screws, bolts, nuts, O-rings etc. When the protective member substantially consists of the fibre-reinforced polymer, manufacture of the protective member is simplified compared to a protective member made from different materials, and moreover the resistance to degradation provided by the fibre-reinforced polymer is utilised readily. This is particularly relevant when the tip section does not comprise a high-nickel alloy, e.g. when the tip section substantially consists of the fibre-reinforced polymer. Thus, the present invention solves the problem of how to simplify the manufacture of a degradation resistant rotary atomizer for a spray drying apparatus, in particular a spray dryer absorber. Since the fibre-reinforced polymer is cheaper than stainless steels and much cheaper than high-nickel alloys, the present invention also provides a cheaper solution to the problem. Furthermore, a protective member, e.g. a frustoconical protective member or a cylindrical protective member, substantially consisting of the fibre-reinforced polymer is lighter than a correspondingly shaped protective member made at least in part from a metal alloy, e.g. a high-nickel alloy, and thereby the protective member is handled more easily than a metallic protective member. In particular, a protective member substantially made from a fibre-reinforced polymer is replaced more easily in an SDA dryer than a protective member made from Hastelloy or other high-nickel alloy or from stainless steel and high- nickel alloy.

The fibre-reinforced polymer may comprise a woven or non-woven mat of glass filaments in a resin matrix of a thermosetting or thermoplastic polymer. This material is commonly known as fiberglass. In general, the protective member may thus be manufactured using any method known in the field and commonly employed in the manufacture of fiberglass materials. For example, the protective member, e.g. a frustoconical protective member or a cylindrical protective member, may be manufactured by hand lay-up of the fibre-reinforced polymer on an appropriately shaped mould or scaffold. Other relevant processes are hand lamination, spray deposition, warm press moulding, and resin transfer moulding.

In another aspect the disclosure provides a spray dryer absorber. The spray dryer absorber may comprise any example of the rotary atomizer of the disclosure, and the spray dryer absorber further includes an absorption chamber, a flue gas inlet and optionally also a drying medium inlet. It is preferred that the flue gas also serves as the drying medium, so that no separate inlet for a drying medium is required. Thus, in an example, the spray dryer absorber does not comprise a drying medium inlet. The flue gas inlet may be positioned at any location in the absorption chamber. For example, the flue gas inlet may be in a bottom section of the absorption chamber, or the flue gas inlet may be in a top section of the absorption chamber. In further examples, the spray dryer absorber comprises a flue gas inlet in the top section of the absorption chamber and a further flue gas inlet in the bottom section of the absorption chamber. When a flue gas inlet is located in the top section of the absorption chamber, it is preferred that the flue gas inlet is near, e.g. adjacent to, the rotary atomizer. It is particularly preferred that the protective member is a frustoconical protective member when the flue gas inlet is adjacent to the rotary atomizer. By having a flue gas inlet adjacent to the rotary atomizer, a more efficient contact between the flue gas and the absorbent is obtained so that pollutants are removed more efficiently from the flue gas. In particular, when the protective member is a frustoconical protective member, the frustoconical protective member focusses the flue gas is at the atomizer wheel to further improve the contact between the flue gas and the feed liquid so that a better absorption is obtained compared to when the protective member has another shape, e.g. when the protective member is a cylindrical protective member. However, since the contact between the flue gas with corrosive pollutants, microdroplets of the absorbent liquid and microparticles formed by reaction between the absorbent and the pollutants, and the protective member is increased, especially when the protective member is a frustoconical protective member, it is particularly advantageous when the protective member, in particular a frustoconical protective member, substantially consists of the fibre-reinforced polymer, or when the protective member, in particular a frustoconical protective member, has a tip section substantially consisting of the fibre-reinforced polymer.

All features and corresponding advantages observed for any embodiment of the aspects relating to rotary atomizer for a spray drying apparatus may be combined freely, only constrained as indicated specifically for individual features. Likewise, all features and corresponding advantages observed for any embodiment of the aspects relating to the rotary atomizer for a spray drying apparatus apply equally to any embodiment of the spray dryer absorber, and all features described for the rotary atomizer may be used freely in any embodiment of the spray dryer absorber.

Brief description of the figures

In the following the invention will be explained in greater detail with the aid of an example and with reference to the schematic drawings, in which

Figure 1 shows schematic drawing of a part of a rotary atomizer;

Figure 2 shows prior art protective member;

Figure 3 shows a schematic drawing of a frustoconical protective member of the present disclosure;

Figure 4 shows a schematic drawing of a spray dryer absorber of the present disclosure;

Figure 5 shows a photograph of a frustoconical protective member of the present disclosure after 12,000 hours of operation.

The invention is not limited to the embodiment/s illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

Detailed description of the invention

The present invention relates to a rotary atomizer for a spray drying apparatus and to a spray dryer absorber comprising the rotary atomizer.

The general configuration of a rotary atomizer 1 is illustrated in Figure 1 . Figure 1 shows the tip section 15 of the protective member 10, an atomizer wheel 3 at the outlet end 12, and a feed inlet 2. The liquid which is to be fed to the atomizer wheel 3 is supplied to the inlet 2 and led to a liquid distributor 21 via a feed conduit 22. The rotary atomizer 1 has a shaft 31 for rotating atomizer wheel 3 about the length axis 13 of the frustoconical protective member 10. The protective member 10 is a frustoconical protective member 10, and the tip section 15 is made of the fibre-reinforced polymer.

Example

A prior art rotary atomizer was manufactured to have a cylindrical protective member to protect the inner parts in the inner volume of the rotary atomizer from the harsh environments in the chamber of a spray dryer absorber. The protective member was made from stainless steel with a tip section made from a Hastelloy, and the stainless steel section was coated with a polymer to protect the stainless steel from corrosion. The rotary atomizer was equipped with an atomizer wheel at the outlet end, and the rotary atomizer was mounted in an F100 spray dryer absorber (GEA Process Engineering A/S, Soborg, Denmark). Specifically, the spray dryer absorber had a flue gas inlet located in a top section of the absorption chamber adjacent to the rotary atomizer.

The spray dryer absorber was operated to treat a flue gas from a garbage incineration plant, where the flue gas was supplied at an inlet temperature of 245°C and the feed liquid was a saturated solution of CaO.

A photograph of the protective member after use for several years is shown in Figure 2. Figure 2 shows that the Flastelloy-part of the protective member is very corroded and the polymer coating (the black part) of the protective member had peeled off during operation.

Rotary atomizers 1 according to the present disclosure as illustrated in Figure 3 were constructed to have a frustoconical protective member 10 with a flange 14 for mounting in a spray dryer absorber 100. In Figure 4 the rotary atomizer 1 is illustrated mounted in a spray dryer absorber. The frustoconical protective member 10 and the flange 14 were made as a single piece from a fibre-reinforced polymer. Specifically, frustoconical protective members 10 were made of fiberglass of random-direction or unidirectional glass fibres embedded in a resin matrix, Derakane 470-300, with a glass transition temperature of 165°C. The frustoconical protective member 10 had a wide inlet end 11 and a narrow outlet end 12, which define a length axis 13 of the frustoconical protective member 10. The feed inlet 2 is at the wide inlet end 11 , and the atomizer wheel 3 is mounted at the narrow end 12. The tip section 15 is especially exposed to corrosive and abrasive conditions when the rotary atomizer 1 is mounted in a spray dryer absorber 100.

The rotary atomizer 1 was mounted in spray dryer absorbers 100 as illustrated in Figure 4. The spray dryer absorber 100 has the rotary atomizer 1 and an absorption chamber 101. The spray dryer absorber 100 as illustrated has an upper flue gas inlet 102 located adjacent to the narrow outlet end 12 and thereby adjacent to the atomizer wheel 3. The illustrated spray dryer absorber 100 also has a lower flue gas inlet 103, although spray dryer absorber 100 may have only the upper flue gas inlet 102 or only the lower flue gas inlet 103. The gas flows in the absorption chamber 101 are illustrated with arrows.

The rotary atomizer 1 in the spray dryer absorber was operated with flue gas inlet temperatures of 245°C, but other test specimens of the rotary atomizer 1 were tested in the laboratory. Despite the fact that the glass transition temperature is dramatically lower than the gas inlet temperature and the fiberglass frustoconical protective members 10 are exposed to highly corrosive and abrasive environments, the tests evidently show that fiberglass frustoconical protective members 10 to be a great advantage compared with frustoconical protective members made of Hastelloy and stainless steel.

The robustness of the frustoconical protective member 10 was tested at high temperatures in thermogravimetric analyses. The test shows that the frustoconical protective member 10 material is robust at temperatures up to 245°C, despite the lower glass transition temperature of the resin. Above 245°C, the frustoconical protective member material burns off, thus degrading the mechanical strength of the material. However, by selecting a resin having a higher glass transition temperature, e.g. about 195°C, the frustoconical protective member 10 can also be operated at temperatures higher than 245°C.

To analyse the temperature pattern, which a frustoconical protective member 10 is exposed to under operation, two frustoconical protective member 10 were provided with four integrated thermocouples shown as A, B, C and D in Figure 3. The frustoconical protective members 10 were installed in a set-up corresponding to the set-up in a spray dryer absorber. Specifically, gasses with temperatures of 245°C or 265°C were applied, and the temperatures were recorded. In chambers with gas inlet temperatures of 245°C, a highest temperature of about 125°C for the frustoconical protective member 10 was observed at the tip section 15. Halfway up the same frustoconical protective member 10, the temperature was measured to only 57°C.

Two frustoconical protective members 10 were tested up to 16,000 hours mounted in spray dryer absorbers 100 (an F100 spray dryer absorber from GEA Process Engineering A/S, Soborg, Denmark) in a garbage incineration plant with gas inlet temperatures of 245°C, which thus corresponds to a temperature of up to 125°C at the tip section 15 of the frustoconical protective member 10. After 12,000 hours of operation, one frustoconical protective members 10 was removed and a photograph of the frustoconical protective members 10 is shown in Figure 5, which shows that the frustoconical protective members 10 could withstand at least 12,000 hours of operation. Analysis of the frustoconical protective members 10 revealed that the fibre- reinforced polymer of the frustoconical protective members 10 did not delaminate even after 16,000 hours of operation.

Reference numerals

1 Rotary atomizer

10 Protective member

11 Inlet end

12 Outlet end

13 Length axis

14 Flange

15 Tip section

16 Inner volume

2 Feed inlet

21 Liquid distributor

22 Feed conduit

3 Atomizer wheel 31 Shaft

100 Spray dryer absorber

101 Absorption chamber

102 Upper flue gas inlet

103 Lower flue gas inlet

Claims

P A T E N T C L A I M S

1. A rotary atomizer (1 ) for a spray drying apparatus, the rotary atomizer (1 ) comprising: a protective member (10) surrounding an inner volume (16) of the rotary atomizer (1 ), the protective member (10) having an inlet end (11 ) and an outlet end (12), and a feed inlet (2) in fluid communication with an atomizer wheel (3) at the outlet end (12), wherein the protective member (10) is made from a material comprising a fibre-reinforced polymer of a woven or non-woven mat of glass or carbon filaments in a resin matrix of a thermosetting or thermoplastic polymer having a glass transition temperature of at least 125°C.

2. The rotary atomizer (1 ) for a spray drying apparatus according to claim 1 , wherein the woven or non-woven mat of glass or carbon filaments is present in an amount of 25 wt% to 75 wt% of the dry weight of the fibre- reinforced polymer.

3. The rotary atomizer (1 ) for a spray drying apparatus according to claim 1 or 2, wherein the material of the protective member (10) substantially consists of the fibre-reinforced polymer.

4. The rotary atomizer (1 ) for a spray drying apparatus according to claim 1 or 2, wherein a tip section (15) constituting up to 15% of the total length of the protective member (10) from the outlet end (12) of the protective member (10) does not comprise a high-nickel alloy.

5. The rotary atomizer (1 ) for a spray drying apparatus according to claim 1 or 2, wherein a tip section (15) constituting up to 15% of the total length of the protective member (10) from the outlet end (12) of the protective member (10) substantially consists of the fibre-reinforced polymer.

6. The rotary atomizer (1 ) for a spray drying apparatus according to any one of claims 1 to 5, wherein the protective member (10) is a frustoconical the protective member (10).

7. A spray dryer absorber (100) comprising a rotary atomizer (1 ) according to any one of claims 1 to 6, an absorption chamber (101 ), a flue gas inlet (102,103) and optionally also a drying medium inlet.

8. The spray dryer absorber (100) according to claim 7, wherein the flue gas inlet (102) is located in a top section of the absorption chamber.

9. The spray dryer absorber (100) according to claim 8, wherein the flue gas inlet (102) is adjacent to the rotary atomizer (1).

10. The spray dryer absorber (100) according to claim 9, wherein the protective member (10) is a frustoconical protective member (10).