EP3976264A1

EP3976264A1 - Cyclone preheater vortex detector for the cement industry, based on sintered silicon carbide

Info

Publication number: EP3976264A1
Application number: EP20746688.9A
Authority: EP
Inventors: Shailesh KUMAR DOSHI; Subhasis Nandi; Frédéric ROULET
Original assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Current assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Priority date: 2019-05-31
Filing date: 2020-05-29
Publication date: 2022-04-06
Also published as: WO2020240102A1

Abstract

Vortex detector (112) for a cyclonic separator (100), comprising a plurality of rings (118) stacked one on another and secured to one another; each ring (118) comprising a plurality of nesting elements (116) which are aligned on a given level; the nesting elements (116) of one of the rings (118) being suspended under the force of gravity and each nesting element (116) being connected to another nesting element (116) of another ring (118), and in turn joining the rings (118) to one another so as to form a closed annular assembly; at least one nesting element (116) comprising a sintered silicon carbide material.

Description

CYCLONE PREHEATER VORTEX DETECTOR FOR THE CEMENT INDUSTRY BASED ON SRIED SILICON CARBIDE

Technical area

The present invention relates to a cyclonic separator for separating solids from gases, and more particularly a vortex detector or vortex sensor (also called “vortex finder” according to the English term) of a cyclonic separator exhibiting a performance improved and reduced maintenance.

Prior art

[0002] The description of the prior art includes information which is useful for an understanding of the present invention. It is not considered that all of the information provided herein is within the domain of the relevant prior art to the present invention as claimed or that any publication specifically or implicitly referenced is necessarily part of the enforceable prior art.

[0003] A cyclone separator is a cylindrical or conical receptacle intended to remove solid particles from a gas flow or from a liquid flow without resorting to a filter in the industrial field such as cement factories. He uses the effect of rotation and gravity to separate these mixtures. The air circulates in a helical fashion forming an external and internal vortex or vortex. The outer vortex separates the larger solid particles present in the gas and the inner vortex separates the coarse particles from the fines.

The gas stream loaded with solid particles is introduced into the cyclone at an angle and swirls cyclonically forming an outer vortex or vortex in order to separate the larger particles from said gas stream by centrifugal force. The centrifugal force created by the cyclonic action pushes larger or heavier particles against the wall of the cyclone separator. After hitting the wall, these particles fall into a hopper (or "Hopper" according to the Anglo-Saxon term) located below. Then the gas stream arrives at the bottom of the cyclone separator, the gas stream turns around by spinning upwards, driving the finest or lightest particles through an exhaust or an outlet called a vortex detector or vortex sensor ( or “vortex finder” according to the usual Anglo-Saxon term) or also referred to as the dip tube or immersion pipe (respectively “dip tube / pipe” or “immersion tube / pipe” according to the Anglo-Saxon terms).

[0005] The vortex detector is a conventional component of cyclone separators. Cyclone Separator Vortex Detectors are tubular in shape and extract light particles from the bottom up. The vortex detector is composed of rings or rows of interlocked plates ("interlocked plates" as the English term) made of metal and stacked to form an annular structure.

[0006] Currently, vortex detectors which are made of metal are naturally subject to severe constraints of the mechanical, chemical and thermal type. These metals are highly unstable at high temperature which leads to severe deformation, severe abrasion, chemical attack and severe corrosion. The worn parts cause a thermal leak over time and a pressure drop in the cyclone separator. In order to maintain the heat and pressure in the cyclone separator, the vortex detector should be replaced regularly. In addition, the metal structure is much heavier than ceramic because the metal is inherently heavy in nature, and its weight must be supported by the cyclonic separation device, leading to even more stress on it. There is therefore a need to replace the metal with other suitable materials capable of overcoming the above shortcomings.

[0007] US patent 4,505,051 A discloses a kind of vortex detector which is not homogeneous. It is composed of a refractory metal at its upper part and of a ceramic material for its lower part. According to this patent the advantage is a considerably increased lifetime of the vortex detector compared to conventional systems. Such a vortex detector, however, has limitations because its upper half is still made of metal that does not fit. resist strong mechanical, chemical or thermal stresses. In addition, this patent does not describe which particular ceramic materials should be used.

[0008] Therefore, in order to minimize metal reuse in a vortex detector and reduce the maintenance and increase the performance of cyclone separators, other materials should be explored. The present invention provides a vortex or dip tube detector made primarily of ceramic. The possibility of deformation, corrosion and erosion is reduced when a ceramic material is used. In addition, the ceramic material is stronger and has a lower weight and can withstand high stresses without deformation or thermal loss. The present invention discloses a vortex detector mainly made of ceramic which is not only refractory but which also withstands the most severe mechanical stresses. In order to strengthen the assembly, metal components can be used only for additional locking for parts subject to high mechanical impact and lower exposure to erosion and corrosion.

Disclosure of the invention

[0009] According to one aspect, the present invention discloses a vortex detector or cyclonic separator dip tube based on sintered silicon carbide. A vortex detector 112 of a cyclone separator 100 comprising a plurality of rings or rows 118 stacked on top of each other and secured with respect to each other. Each ring 118 comprises a plurality of interlocking elements 116 (or interlocking members in English) which are aligned on the same level. The interlocking elements 116 of one of the rings 118 are suspended under the action of the force of gravity and each interlocking element 116 is connected to another interlocking element 116 of another ring 118, in turn, ensuring the junction of the rings 118 between them so as to form a closed annular assembly. At least one interlocking member 116 comprises a silicon carbide material sintered between 800 ° C and 2500 ° C, preferably between 1000 ° C and 2300 ° C, more preferably between 1200 ° C and 2000 ° C. [0010] Sintered silicon carbide has a thermal expansion coefficient of between 4 x 10 ⁶ ° K ^_1 and 5.1 x 10-6 ° K ^_1 measured between room temperature and 1000 ° C according to the ASTM C832 standard, a density between 2.40 g / cm ³ (or at least 2.45) g / cm ³ and 3.13 g / cm ³ , a thermal conductivity between 8 W / mK and 130 W / mK measured between room temperature and 1200 ° C according to standard ASTM E1461, an abrasion resistance in the range of 0.25 cm ³ to 6 cm ³ measured according to standard ASTM C704, a modulus of rupture (in bending) between 15 MPa and 600 MPa measured according to standard ASTM 033, a mechanical resistance to cold crushing between 45 MPa and 4000 MPa measured according to standard ASTM 033 and a maximum operating temperature between 1300 ° C to 2200 ° C.

[0011] Other features and aspects of the invention will be more apparent from the following detailed description and accompanying figures.

Brief description of the figures:

[0012] The embodiments which are illustrated in the following figures are illustrated by way of example and are not limiting

[0013] FIG. 1 illustrates a cyclone separator according to an embodiment of the present invention;

[0014] FIG. 2 illustrates a vortex detector or vortex sensor according to one embodiment of the present invention;

[0015] FIG. 3 illustrates a sectional view of a vortex detector according to one embodiment of the present invention;

[0016] FIG. 4 illustrates an interlocking element of a vortex detector according to one embodiment of the present invention;

[0017] FIG. 5 illustrates a flowchart relating to a method of fabricating a sintered silicon carbide material of the interlocking member of the vortex detector according to one embodiment of the present invention;

The person skilled in the art knows how to appreciate the elements in the figures illustrated with simplicity and clarity which are not necessarily made to scale. For example, the dimensions of one of the elements in the figures may be exaggerated with respect to other elements in order to allow a better understanding of the embodiments according to the invention.

Detailed Description

The present invention relates to a vortex detector based on sintered silicon carbide of a cyclonic separator of a clinker cement calcination plant suitable for use under high temperature conditions and having a low coefficient of expansion thermal and high resistance to corrosion and heat. The possibility of thermal shock cracking is greatly reduced by the use of a sintered silicon carbide based vortex detector. This increases the life of the vortex detector and has a strong economic impact. The vortex detector is also called an immersion tube ("immersion tube" according to the Anglo-Saxon term) or dip tube ("dip tube according to the Anglo-Saxon term) or even" thimble "according to the Anglo-Saxon term.

[0020] FIG. 1 illustrates a cyclone separator 100. The cyclone separator 100 includes a housing 102, a cyclone reservoir 110, a gas inlet 104, a gas outlet 106, a particle outlet 108, and a vortex detector 112. The charged gas stream The solid particles are fed into the housing 102 through the inlet 104. The particles are separated in the cyclone reservoir 110. The larger or heavier particles fall into the outlet port 108. The finer or more particles. The lighter particles are drawn upward into the vortex detector 112. The vortex detector 112 leads to the gas outlet 106. The lighter particles are removed through the gas outlet 106. The vortex detector 112 is located in the center of the gas outlet. housing 102 within the cyclone separator 100 and suspended using a support ring 114 in the upper part of the housing 102 of the cyclone separator 100 and is deployed in the housing 102.

[0021] FIG. 2 illustrates a vortex detector 112 based on sintered silicon carbide of a cyclone separator 100 in a perspective view. FIG. 3 illustrates a sectional view of a vortex detector 112. The vortex detector 112 is composed of a plurality of interconnected rings 118 assembled together. to each other by their upper part to form the vortex detector 112. The row or ring 118 comprises a plurality of interlocking members 116 which are aligned on a same level. The interlocking elements 116 have a similar shape and are made of sintered silicon carbide. The first row or ring 118 interlocking members 116 of the top of the vortex detector 112 are suspended by a support ring 114 (not shown in the figure) from the housing 102 (not shown) of the cyclone separator 100 (not shown). At least one row 118 or the others are maintained by a belt or equivalent means. The interlocking elements 116 of one of the lower rings 118 are suspended under the force of gravity by the interlocking elements of an upper ring 118. This successive positioning of adjoining rings makes it possible to form an assembly of closed rings. An additional locking element may or may not be applied on a case-by-case basis depending on the severity of the vibrations or turbulence in the vortex detector. In each case, this is designed after evaluating how the self-locking of the interlocking elements 116 of a ring 118 will provide adequate locking force or not.

[0022] According to one embodiment, the components of the vortex detector 112 are made mainly of sintered silicon carbide. The firing or sintering of the silicon carbide is carried out at a temperature between 800 ° C and 2500 ° C, preferably between 1000 ° C and 2300 ° C, more preferably between 1200 ° C and 2000 ° C. The silicon carbide is sintered in an atmosphere of gases selected from oxygen, nitrogen, argon or a combination of these gases. Sintered silicon carbide shows properties of high hardness, low density compared to metal and low porosity, good wear resistance, excellent corrosion resistance, low coefficient of thermal expansion and high thermal conductivity in comparison with other ceramics. The sintered silicon carbide preferably has a thermal expansion coefficient of between 4 ^c 10 ⁶ ° K ^_1 and 5.1 ^c 10 ⁶ ° K ^_1 , measured between ambient temperature and 1000 ° C according to the standard ASTM C832 and / or a apparent density between at least 2.45 and 3.13 g / cm ³ and / or a thermal conductivity between 8 W / mK and 130 W / mK measured between room temperature and 1200 ° C according to the ASTM standard E1461 and / or an abrasion resistance in the range of 0.25 cm ³ to 6 cm ³ measured according to standard ASTM C704 and / or a modulus of rupture between 15 MPa and 600 MPa measured according to standard ASTM 033 and / or a mechanical resistance to cold crushing between 45 MPa and 4000 MPa measured according to standard ASTM 033 and a maximum temperature of use between 1300 ° C to 2200 ° C.

[0023] According to one possible embodiment, the sintered silicon carbide according to the invention is either linked by itself ("self-bonded" in English) or linked to other materials. Many bonding systems are used to sinter silicon carbide eg alumina, mullite, oxide, clay, nitride, oxynitride, SiAlON, bonding by SiC itself or "auto -lié ”(“ self-bonded ”in English), recrystallization, are some systems but the invention is not limited to them. In the case of self-bonded silicon carbide, the silicon carbide (SiC) grains are bonded by a SiC matrix or bonded together directly. Among the self-bonded silicon carbides are dense silicon carbide and recrystallized silicon carbide. Recrystallized silicon carbide is obtained by recrystallization via the evaporation and recondensation of a mixture of SiC raw material at a temperature above 2200 ° C in an inert atmosphere (usually argon) typically in induction furnaces. This process solidifies the microstructure of silicon carbide and results in a material called recrystallized silicon carbide. In the case of silicon carbide bound by a silicate oxide phase, the SiC grains are mixed with silicates such as clay, mullite and the mixture is fired in a gas oven under an oxidizing atmosphere at a temperature typically up to 1400 ° C. Oxide-bonded silicon carbide is formed from a mixture of SiC particles and materials such as metal oxides, such as aluminum oxide and / or silicon oxide. The mixture is then fired under an oxidizing atmosphere which partially oxidizes the silicon carbide particles and a bond occurs between the SiC particles and the silica generated by the partial oxidation of the SiC particles. Nitrogen bonded silicon carbide is obtained by firing mixtures of high purity silicon carbide, silicon or mineral additives in a nitrogenous atmosphere at high temperature (typically 1350 ° C to 1450 ° C). Silicon carbide may be bound by a silicon nitride phase (SÎ3N4) which forms during firing. The oxynitride bonded silicon carbide is formed from silicon carbide, silicon and mineral additives fired under a nitrogen atmosphere and optionally oxygen. The Si Al ON usually described in the quaternary diagram SÎ3N4-A1N-A1203-SI02 are formed by reaction between different precursors such as silicon nitride (SÎ3N4), aluminum oxide (A1203) and aluminum nitride ( AIN). These precursors are initially present or intermediate components obtained during the reaction for the formation of the matrix binding the grains of silicon carbide.

The advantage of using various varieties of sintered silicon carbide which exhibit a wide range of properties is that the appropriate material can be used for the various components of the vortex detector 112 depending on the design requirements of the device. each vortex.

[0025] According to one possible embodiment, the interlocking elements (interlocking members) 1 16 are made of sintered silicon carbide. According to a preferred embodiment, the majority of the interlocking elements comprise sintered silicon carbide. The majority means more than 50% by number, preferably more than 70% or at least more than 80% of the interlocking elements comprise sintered silicon carbide.

[0026] According to one possible embodiment, the interlocking members 116 have a Z profile, but the invention is not limited to this particular profile. Any self-bonded or other material bonded silicon carbide can be used depending on the design requirements of the vortex detector.

[0027] FIG. 4 illustrates an example of an interlocking member profile 116. The Z-shaped profile comprises a base 120 with two side flanges or flanges (“lateral flanges” in English) where a first flange 122 and a second flange 124 extend in a direction opposite to each other. The first flange 122 includes at least 2 or more other upwardly projecting teeth. The second flange 124 comprises at least 2 or even more other through openings (pass-through openings). The teeth of the first flange 122 of the Z-shaped interlocking members 116 of a row or ring 118 (not shown) engage with the openings of the second flange 124 of an interlocking member (interlocking members) 116 Z-shaped from another row or ring 118 (not shown). The shapes shown are not limiting and can be adapted depending on the design of the vortex detector. In particular, the base 120 may be essentially flat and / or comprise a cross-shaped rib parallel to or along the diagonals of at least one of the faces of the base 120.

[0028] FIG. 5 illustrates a flowchart relating to a method 500 of making a sintered silicon carbide material of the interlocking member 116 of the vortex detector 112 of a cyclone separator 100 in accordance with one embodiment of the present invention. Step 501 includes making a mixture of raw materials. Raw materials include silicon carbide alone or with other bonding materials depending on the required properties and particular functions. The bonding materials can be selected by clay, mullite, silicon or metal oxides, the metal oxides including in particular alumina and / or silica. The raw materials are weighed in a particular proportion and mixed using a mixer or a ball mill or a jar mixer. Step 502 includes shaping the mixture to make a body preformed or shaped by different processes such as pressing, vibro-pressing or various casting techniques. Step 503 includes drying the shaped body by air drying or in a low temperature oven. Step 504 includes firing the dried shaped body between 800 ° C and 2500 ° C, preferably between 1000 ° C and 2300 ° C, more preferably between 1200 ° C and 2000 ° C, in a sintering furnace under inert atmosphere, oxygen or nitrogen.

Examples

Example 1

The table below indicates the sintering temperatures of the different types of silicon carbide.

Table 1: Sintering temperature

Example 2

The table below shows the physical properties of different types of sintered silicon carbide.

Table 2: Physical properties

The different types of sintered silicon carbide have a high thermal conductivity and a low coefficient of thermal expansion; therefore, it is very resistant to thermal shock and survives rapid thermal cycles compared to other materials.

Abrasion resistance is generally associated with great hardness and great mechanical strength. The extreme hardness makes the sintered silicon carbide resistant to wear and erosion under conditions of mechanical abrasion.

It should be noted that all the activities described above in the general description or the examples are not required, that part of a specific activity may not be required and that one or more other activities may be carried out in more than those described. Also, the order in which the activities are listed is not necessarily the order in which they are performed.

[0034] The benefits, other advantages, and solutions to the problems have been described above with respect to specific embodiments. However, advantages, benefits, solutions to problems and any characteristic (s) that could result in or make a benefit, benefit or solution more pronounced, should not be interpreted as a critical characteristic. , required or essential to one or all of the claims.

[0035] The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various modes. The description and illustrations are not intended to serve as an exhaustive and complete description of all the elements and characteristics of devices and systems which use the structures or methods described herein. For the sake of clarity, certain features described herein in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, certain characteristics which are, for the sake of brevity, described in the context of a single embodiment, may also be provided separately or in a sub-combination. In addition, the reference to the values indicated in the intervals includes every value of that interval. Many other embodiments may not be apparent to skilled artisans until after reading this description. Other embodiments can be used and derived from the disclosure, so that structural substitution, logical substitution, or other change can be made without departing from the scope of the disclosure. Accordingly, the information should be considered illustrative rather than restrictive.

[0036] The description combined with the figures is provided to help understand the teachings disclosed herein, is provided to help describe the teachings, and should not be construed as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

As used in this document, the terms "includes", "includes", "including", "a", "having" or any other variation of these terms, are intended to cover an inclusion not exclusive. For example, a method, item or device that includes a list of features is not necessarily limited to those features but may include other features that are not expressly listed or inherent in that method, item, or device. . Further, unless expressly stated otherwise, "or" refers to an "or" inclusive and not to an "or" exclusive. For example, a condition A or B is satisfied by one of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and A and B are both true (or present).

[0038] Likewise, the use of "a" or "a" is employed to describe the elements and components described herein. This is done simply for convenience and to give a general idea of the scope of the invention. This description should be read as including one or at least one and the singular also includes the plural, or vice versa, unless it is clear that this is otherwise. For example, when a single item is described here, multiple items can be used instead of a single item. Likewise, when more than one element is described here, a single element may be substituted for multiple elements.

[0039] Unless defined otherwise, all the technical and scientific terms used in this document have the same meaning as that which is commonly attributed to them by specialists in the art to which this invention belongs. The materials, methods and examples are given for illustration only and are not intended to be limiting. As some details regarding specific materials and acts of processing are not described, these details may include conventional approaches, which can be found in reference books and other sources in the manufacturing arts.

Although certain aspects of the present disclosure have been particularly shown and described with reference to the above embodiments, it will be understood by those skilled in the art that various additional embodiments can be envisaged by modifying the machines, systems and methods disclosed without s 'depart from the spirit and scope of what is disclosed. Such embodiments are to be understood as falling within the scope of this disclosure, as determined on the basis of the claims and their equivalents.

List of clues

CYCLONE PREHEATER VORTEX DETECTOR FOR

THE SRIED SILICON CARBIDE CEMENT INDUSTRY

100 cyclonic separator

102 accommodation

104 gas inlet

106 gas outlet

108 particle exit

110 cyclone tank

112 vortex detector or Vortex Finder dip tube

114 support ring

116 interlocking element

118 ring

120 base

122 first flange or flange

124 second flange or flange

500 method

501 step

502 step

503 step

504 step

Claims

1. Vortex finder 112 for a cyclone separator 100 comprising:

a plurality of rings 118 stacked one on top of the other and fixed to one another;

- wherein each ring 118 comprises a plurality of interlocking members 116 which are aligned on the same level;

- wherein the interlocking elements 116 of one of the rings 118 are suspended under the force of gravity and each interlocking element 116 is connected to another interlocking element 116 of another ring 118, in turn, ensuring the junction of the rings 118 together so as to form a closed annular assembly;

-wherein at least one interlocking element 116 comprises a sintered silicon carbide material;

- in which the sintered silicon carbide has a density of between 2.40 and 3.13 g / cm ³ at least and a modulus of rupture of between 15 MPa and 600 MPa measured according to the ASTM Cl 33 standard.

2. Vortex detector 112 for a cyclone separator 100 according to claim 1, wherein the sintered silicon carbide has an abrasion resistance in the range of 0.25 cm ³ to 6 cm ³ measured according to ASTM C704.

3. Vortex detector 112 for a cyclone separator 100 according to claim 1, in which the interlocking elements 116 are made of sintered silicon carbide.

4. Vortex detector 112 for a cyclone separator 100 according to claim 1, wherein the majority of the interlocking elements 116 comprise sintered silicon carbide.

5. Vortex detector 112 for a cyclone separator 100 according to claim 1, wherein the silicon carbide is sintered in the atmosphere of gases selected from the group consisting of oxygen, nitrogen, argon or a combination. of these.

6. Vortex detector 112 for a cyclonic separator 100 according to claim 1, wherein the sintered silicon carbide is either self-bonded or bonded with a material selected from the group consisting of, but not limited to, silicate. , nitrogen or oxygen.

7. Vortex detector 112 for a cyclone separator 100 according to claim 6, wherein the self-bonded silicon carbide is selected from the group consisting of dense sintered silicon carbide or recrystallized silicon carbide.

A vortex detector 112 for a cyclone separator 100 according to claim 6, wherein the silicon carbide bonded with silicate is selected from the group consisting of silicon carbide bonded with clay, silicon carbide bonded with mullite. , silicon carbide bonded with alumina or silicon carbide infiltrated with silicon (Si-SiC).

9. Vortex detector 112 for a cyclone separator 100 according to claim 6, wherein the nitrogen-bonded silicon carbide is selected from the group consisting of nitride-bonded silicon carbide, silicon carbide bonded with a nitride. oxynitride or silicon carbide bonded with a si al on.

10. A method of manufacturing a sintered silicon carbide material of the interlocking member of the vortex detector 112 of the cyclone separator 100 according to claim 1, comprising:

forming a mixture of raw materials;

making the mixture into a shaped body;

drying the manufactured shaped body; and

sintering the dried shaped body between 1000 ° C and 2500 ° C.

11. The manufacturing method according to claim 10, wherein the raw material comprises silicon carbide and additives.

12. The manufacturing method according to claim 11, wherein the additives are selected from the group consisting of clay, mullite, silicon, metal oxides or a combination thereof.