JP2002286397A - Heat transfer tube for heat exchanger - Google Patents
Heat transfer tube for heat exchangerInfo
- Publication number
- JP2002286397A JP2002286397A JP2001090388A JP2001090388A JP2002286397A JP 2002286397 A JP2002286397 A JP 2002286397A JP 2001090388 A JP2001090388 A JP 2001090388A JP 2001090388 A JP2001090388 A JP 2001090388A JP 2002286397 A JP2002286397 A JP 2002286397A
- Authority
- JP
- Japan
- Prior art keywords
- heat exchanger
- silicon nitride
- sintered body
- heat transfer
- transfer tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、熱交換システムに
用いられる熱交換器用伝熱管に関し、特に窒化ケイ素質
焼結体からなる熱交換器用伝熱管に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger tube for a heat exchanger used in a heat exchange system, and more particularly to a heat exchanger tube made of a silicon nitride sintered body.
【０００２】[0002]
【従来の技術】焼却、発電プラントなどで発生する高温
廃ガスの持つ熱エネルギーを有効利用し、プラント全体
としてエネルギー効率を上げるため、高温廃ガスが発生
もしくは通過する空間に隔壁として熱交換器用伝熱管を
配置し、その伝熱管の内部に低温の被加熱ガスを送り込
み、熱伝達により被加熱ガスを加熱する方式の熱交換器
が用いられている。従来の熱交換システムにおいては、
金属製の伝熱管が用いられていたが、使用温度が１００
０℃以上と高いうえ、ガス自体の腐食性が強いため不適
であった。このため、これに代わるものとして、例えば
特開２０００−１９３３８４号公報、特開２０００−１
８８５０号公報などに示される窒化ケイ素などのセラミ
ックスからなる伝熱管が使われている。2. Description of the Related Art In order to effectively utilize the heat energy of high-temperature waste gas generated in incineration and power generation plants and to improve energy efficiency as a whole plant, a heat exchanger is used as a partition in a space where high-temperature waste gas is generated or passes. A heat exchanger of a type in which a heat pipe is arranged, a low-temperature gas to be heated is sent into the heat transfer pipe, and the gas to be heated is heated by heat transfer is used. In conventional heat exchange systems,
A metal heat transfer tube was used, but the operating temperature was 100
The temperature was as high as 0 ° C. or higher and the gas itself was highly corrosive. For this reason, as alternatives, for example, JP-A-2000-193384, JP-A-2000-1
A heat transfer tube made of ceramics such as silicon nitride disclosed in Japanese Patent No. 8850 or the like is used.
【０００３】特開２０００−１９３３８４号公報には、
一端が開口され他端が閉塞した筒状体、または両端が開
口した筒状体からなり、その外周面が高温雰囲気に晒さ
れ、内部で熱交換用の流体を流通させるようにした熱交
換器用伝熱管であって、気孔率が１０〜３５％で、熱衝
撃温度５００℃での初期室温強度からの劣化率が４０％
以下であるセラミックスを用いた熱交換器用伝熱管が記
載されている。このセラミックスとしては、平均粒径が
５〜５０μｍのＳｉＣ結晶粒子を１０〜３０重量％、平
均粒径が０．５〜５μｍのＳｉＣ結晶粒子またはＳｉ3
Ｎ4粒子を６０〜８５重量％、Ａｌ2Ｏ3を１〜５重量
％、Ｙ2Ｏ3を０．１〜５重量％含有する多孔質複合セラ
ミックスを用いる。同公報の表１、表２に示す本発明の
試料Ｎｏ．１７（粗大ＳｉＣ粒子を１０重量％、微細Ｓ
ｉ3Ｎ4粒子を７８重量％、Ａｌ2Ｏ3を３．５重量％、Ｙ
2Ｏ3を３．０重量％を含有する窒化ケイ素系の複合セラ
ミックス）の熱伝導率は２２Ｗ／（ｍ・Ｋ）、本発明の
範囲外である試料Ｎｏ．１５（粗大ＳｉＣ粒子を５重量
％、微細Ｓｉ3Ｎ4粒子を８８重量％、Ａｌ2Ｏ3を１．５
重量％、Ｙ2Ｏ3を２．０重量％を含有する窒化ケイ素系
の複合セラミックス）の熱伝導率は２８Ｗ／（ｍ・Ｋ）
であることが記載されている。[0003] JP-A-2000-193384 discloses that
For heat exchangers consisting of a tubular body open at one end and closed at the other end, or a tubular body open at both ends, the outer peripheral surface of which is exposed to a high-temperature atmosphere and allows a heat exchange fluid to flow inside. A heat transfer tube having a porosity of 10 to 35% and a deterioration rate of 40% from initial room temperature strength at a thermal shock temperature of 500 ° C.
A heat exchanger tube for a heat exchanger using the following ceramics is described. Examples of the ceramic include 10 to 30% by weight of SiC crystal particles having an average particle size of 5 to 50 μm and SiC crystal particles or Si 3 having an average particle size of 0.5 to 5 μm.
The N 4 particles 60 to 85 wt%, the Al 2 O 3 1 to 5 wt%, a porous composite ceramic containing Y 2 O 3 0.1 to 5 wt%. The sample Nos. Of the present invention shown in Tables 1 and 2 of the publication are shown in FIG. 17 (10% by weight of coarse SiC particles, fine S
78% by weight of i 3 N 4 particles, 3.5% by weight of Al 2 O 3 , Y
The thermal conductivity of the silicon nitride-based composite ceramic containing 3.0% by weight of 2 O 3 ) was 22 W / (m · K), which was out of the range of the present invention. 15 (5 wt% coarse SiC particles, 88 wt% of fine Si 3 N 4 particles, the Al 2 O 3 1.5
The thermal conductivity of a silicon nitride-based composite ceramic containing 2.0% by weight and 2.0% by weight of Y 2 O 3 is 28 W / (m · K).
Is described.
【０００４】特開２０００−１８８５０号公報には、内
外で熱交換を行なうようにした伝熱管をセラミックスで
形成するとともに、その内面に複数のフィンを一体的に
形成した熱交換器用伝熱管が記載されている。この熱交
換器用伝熱管は、伝熱管内面の表面積を増やすことがで
きるため、熱伝達効率を高くできる。伝熱管をなすセラ
ミックスとしては、炭化ケイ素や窒化ケイ素などを用い
る。同公報の表５に示す窒化ケイ素の熱伝導率は２０Ｗ
／（ｍ・Ｋ）であることが記載されている。Japanese Patent Application Laid-Open No. 2000-18850 discloses a heat exchanger tube for a heat exchanger in which a heat exchanger tube for performing heat exchange inside and outside is formed of ceramics and a plurality of fins are integrally formed on an inner surface thereof. Have been. Since the heat transfer tube for a heat exchanger can increase the surface area of the inner surface of the heat transfer tube, the heat transfer efficiency can be increased. Silicon carbide, silicon nitride, or the like is used as ceramics forming the heat transfer tube. The thermal conductivity of silicon nitride shown in Table 5 of the publication is 20 W
/ (M · K).
【０００５】[0005]
【発明が解決しようとする課題】前記従来の窒化ケイ素
からなる熱交換器用伝熱管においては、その熱伝導率が
高々２０〜３０Ｗ／（ｍ・Ｋ）である。そこで、伝熱管
の熱伝達効率を高くするために、伝熱管の内面あるいは
外面にフィンを設けたりして伝熱管の表面積を増やして
いた。そのため、伝熱管の製作が煩雑になったり、設備
の省スペースの妨げとなっていた。The heat transfer tube of the above-mentioned conventional heat exchanger made of silicon nitride has a thermal conductivity of at most 20 to 30 W / (m · K). Therefore, in order to increase the heat transfer efficiency of the heat transfer tube, fins are provided on the inner surface or the outer surface of the heat transfer tube to increase the surface area of the heat transfer tube. For this reason, the production of the heat transfer tube becomes complicated, and the space saving of the equipment is hindered.
【０００６】また、伝熱管の熱伝達効率が劣るために、
大型化したり、バーナーを近づけたりすると、伝熱管の
表面部と内部に極端な温度差を生じ、熱応力のため割れ
やクラックが生じる問題があった。[0006] Further, since the heat transfer efficiency of the heat transfer tube is inferior,
Increasing the size or bringing the burner closer causes an extreme temperature difference between the surface portion and the inside of the heat transfer tube, causing cracks and cracks due to thermal stress.
【０００７】したがって、本発明は熱伝達効率が高く、
かつ熱応力による割れやクラックを防止できる熱交換器
用伝熱管を提供することを目的とする。Therefore, the present invention has high heat transfer efficiency,
It is another object of the present invention to provide a heat exchanger tube for a heat exchanger that can prevent cracks and cracks due to thermal stress.
【０００８】[0008]
【課題を解決するための手段】本発明の熱交換器用伝熱
管は、窒化ケイ素を主成分する窒化ケイ素質焼結体から
なり、窒化ケイ素質焼結体の常温における熱伝導率が７
０Ｗ／（ｍ・Ｋ）以上であることを特徴とする。本発明
において、窒化ケイ素質焼結体の常温における４点曲げ
強度が６００ＭＰａ以上であることを特徴とする。窒化
ケイ素質焼結体中のアルミニウムの含有量が０．２重量
％以下であることが好ましい。また、窒化ケイ素質焼結
体中の酸素の含有量が３．０重量％以下であることが好
ましい。A heat exchanger tube for a heat exchanger according to the present invention comprises a silicon nitride sintered body containing silicon nitride as a main component, and has a thermal conductivity of 7 at room temperature.
0 W / (m · K) or more. In the present invention, the silicon nitride sintered body has a four-point bending strength at room temperature of 600 MPa or more. It is preferable that the content of aluminum in the silicon nitride sintered body is 0.2% by weight or less. Further, the content of oxygen in the silicon nitride sintered body is preferably 3.0% by weight or less.
【０００９】[0009]
【作用】本発明は熱交換器用伝熱管を形成する材料自体
の熱伝導率を高めることにより、伝熱管の表面から内部
へ熱を迅速にかつ効率よく伝達させることができ、伝熱
管の表面と内部の温度差を緩和し、熱応力による割れを
防止できる。従来の窒化ケイ素質焼結体は、常温におけ
る熱伝導率が高々２０〜３０Ｗ／（ｍ・Ｋ）程度である
が、本発明の窒化ケイ素質焼結体は、焼結体中に不純物
として存在するアルミニウムおよび酸素の含有量を低減
することにより、７０Ｗ／（ｍ・Ｋ）以上の熱伝導率を
得ることができる。According to the present invention, heat can be quickly and efficiently transferred from the surface of the heat transfer tube to the inside by increasing the thermal conductivity of the material forming the heat transfer tube for a heat exchanger. The internal temperature difference can be reduced and cracks due to thermal stress can be prevented. A conventional silicon nitride sintered body has a thermal conductivity at room temperature of at most about 20 to 30 W / (m · K), but the silicon nitride sintered body of the present invention exists as an impurity in the sintered body. By reducing the content of aluminum and oxygen, a thermal conductivity of 70 W / (m · K) or more can be obtained.
【００１０】窒化ケイ素質焼結体中に不純物として存在
する異種イオン、特にアルミニウム、酸素はフォノン散
乱源となり熱伝導率を低減させる。窒化ケイ素質焼結体
は、窒化ケイ素粒子相とその周囲の粒界相とから構成さ
れ、アルミニウムおよび酸素はこれら二相にそれぞれ含
有される。アルミニウムは、窒化ケイ素の構成元素であ
るケイ素のイオン半径に近いため窒化ケイ素粒子内に容
易に固溶する。アルミニウムの固溶により窒化ケイ素粒
子自身の熱伝導率が低下し、結果として焼結体の熱伝導
率が著しく低下する。The foreign ions, particularly aluminum and oxygen, present as impurities in the silicon nitride sintered body serve as phonon scattering sources and reduce the thermal conductivity. The silicon nitride sintered body is composed of a silicon nitride particle phase and a surrounding grain boundary phase, and aluminum and oxygen are contained in these two phases, respectively. Since aluminum is close to the ionic radius of silicon, which is a constituent element of silicon nitride, aluminum easily forms a solid solution in silicon nitride particles. Due to the solid solution of aluminum, the thermal conductivity of the silicon nitride particles themselves is reduced, and as a result, the thermal conductivity of the sintered body is significantly reduced.
【００１１】また、焼結助剤として主に酸化物を添加す
るため、酸素の多くは粒界相成分として存在する。焼結
体の高熱伝導化を達成するには、主相の窒化ケイ素粒子
に比べて熱伝導率が低い粒界相の量を低減することが肝
要であり、焼結助剤成分の添加量を相対密度８５％以上
の焼結体が得られる量を最小限とし、酸素量を低減させ
ることが必要である。Further, since oxide is mainly added as a sintering aid, most of oxygen exists as a grain boundary phase component. In order to achieve high thermal conductivity of the sintered body, it is important to reduce the amount of the grain boundary phase having a lower thermal conductivity than the silicon nitride particles of the main phase. It is necessary to minimize the amount of a sintered body having a relative density of 85% or more and to reduce the amount of oxygen.
【００１２】また、窒化ケイ素質焼結体中の窒化ケイ素
粒子の性状を最適化することにより、使用中の機械的応
力および衝撃に十分に耐えられる曲げ強度を得ることが
できる。窒化ケイ素質焼結体中のβ型窒化ケイ素粒子の
うち、短軸径５μｍ以上のβ型窒化ケイ素粒子の割合
が、１０体積％以上では焼結体の熱伝導率は向上する
が、組織中に導入された粗大粒子が破壊の起点として作
用するため破壊強度が著しく低下し、６００ＭＰａ以上
の曲げ強度が得られない。したがって、窒化ケイ素質焼
結体中のβ型窒化ケイ素粒子のうち、短軸径５μｍ以上
のβ型窒化ケイ素粒子の割合が１０体積％未満であるこ
とが好ましい。同様に、組織中に導入された粗大粒子が
破壊の起点として作用することを抑えるために、β型窒
化ケイ素粒子のアスペクト比が１５以下であることが好
ましい。Further, by optimizing the properties of the silicon nitride particles in the silicon nitride sintered body, it is possible to obtain a bending strength that can sufficiently withstand mechanical stress and impact during use. When the proportion of β-type silicon nitride particles having a minor axis diameter of 5 μm or more among the β-type silicon nitride particles in the silicon nitride-based sintered body is 10% by volume or more, the thermal conductivity of the sintered body is improved. Since the coarse particles introduced into the material act as a starting point of fracture, the fracture strength is significantly reduced, and a bending strength of 600 MPa or more cannot be obtained. Therefore, it is preferable that the ratio of β-type silicon nitride particles having a minor axis diameter of 5 μm or more to β-type silicon nitride particles in the silicon nitride-based sintered body is less than 10% by volume. Similarly, the aspect ratio of the β-type silicon nitride particles is preferably 15 or less in order to suppress that the coarse particles introduced into the structure act as a starting point of fracture.
【００１３】[0013]
【発明の実施の形態】図１は本発明実施例の熱交換器用
伝熱管の概略図である。図１において、熱交換器用伝熱
管１は中空部２を有する管状体であり、本発明の窒化ケ
イ素質焼結体からなる。そして、焼却、発電プラントな
どで使用される熱交換器において、高温廃ガスが発生も
しくは通過する空間に隔壁として熱交換器用伝熱管１を
配置し、伝熱管１の内部に低温の被加熱ガスを送り込
み、熱伝達により被加熱ガスを加熱する。図１のような
本発明実施例の熱交換器用伝熱管では、製作が容易で構
造的にも設備の省スペースの妨げとならない。ただし、
これらの利点は得られないものの、本発明の熱交換器用
伝熱管は伝熱管の内面あるいは外面にフィンを設けても
構わない。FIG. 1 is a schematic view of a heat exchanger tube for a heat exchanger according to an embodiment of the present invention. In FIG. 1, a heat exchanger tube 1 for a heat exchanger is a tubular body having a hollow portion 2 and is made of a silicon nitride sintered body of the present invention. In a heat exchanger used in an incineration or power plant, a heat exchanger tube 1 for a heat exchanger is arranged as a partition in a space in which high-temperature waste gas is generated or passes. The heated gas is heated by feeding and heat transfer. The heat exchanger tube for a heat exchanger according to the embodiment of the present invention as shown in FIG. 1 is easy to manufacture and does not hinder the space saving of the equipment structurally. However,
Although these advantages cannot be obtained, the heat exchanger tube for a heat exchanger of the present invention may have fins provided on the inner surface or outer surface of the heat exchanger tube.
【００１４】次に熱交換器用伝熱管１の製造方法につい
て説明する。平均粒径０．５μｍの窒化ケイ素粉末に、
焼結助剤として、平均粒径０．２μｍの酸化マグネシウ
ム粉末を２．８体積％、平均粒径０．２μｍの酸化アル
ミニウム粉末を０．０８体積％、平均粒径２．０μｍの
酸化イットリウム粉末を０．４体積％添加し、適量の分
散剤を加えエタノール中で粉砕、混合した。ついで、真
空乾燥後、篩を通して造粒した後、ゴム型に充填し、静
水圧により冷間静水圧プレス（ＣＩＰ）を行い、伝熱管
１となる成形体を作製した。これらの成形体を１７５０
℃、９気圧の窒素ガス雰囲気中で５時間焼成し、本発明
の窒化ケイ素質焼結体を得た。Next, a method of manufacturing the heat exchanger tube 1 for a heat exchanger will be described. Silicon nitride powder with an average particle size of 0.5 μm,
As sintering aids, 2.8% by volume of magnesium oxide powder having an average particle size of 0.2 μm, 0.08% by volume of aluminum oxide powder having an average particle size of 0.2 μm, and yttrium oxide powder having an average particle size of 2.0 μm Was added, and an appropriate amount of a dispersant was added, followed by pulverization and mixing in ethanol. Subsequently, after vacuum drying, the mixture was granulated through a sieve, filled in a rubber mold, and subjected to cold isostatic pressing (CIP) by hydrostatic pressure to produce a molded body to be the heat transfer tube 1. These compacts are
The mixture was fired in a nitrogen gas atmosphere at 9 ° C. and 9 atm for 5 hours to obtain a silicon nitride sintered body of the present invention.
【００１５】得られた窒化ケイ素質焼結体から、直径１
０ｍｍ×厚さ３ｍｍの熱伝導率および密度測定用の試験
片、縦３ｍｍ×横４ｍｍ×長さ４０ｍｍの４点曲げ試験
片を採取した。密度はマイクロメ−タによる寸法測定と
重量測定の結果から求めた。熱伝導率はレーザーフラッ
シュ法により常温での比熱および熱拡散率を測定し熱伝
導率を算出した。４点曲げ強度は常温にてＪＩＳ Ｒ１
６０６に準拠して測定を行った。また、窒化ケイ素粒子
の体積％は、焼結体をフッ化水素酸にて粒界ガラス相を
溶出することにより、窒化ケイ素粒子を個々に取り出し
ＳＥＭ観察して求めた。本発明では、面積％の値を体積
％として評価した。窒化ケイ素質焼結体中のアルミニウ
ム含有量は誘導プラズマ発光分析法（略称ＩＣＰ法）に
より、酸素含有量は赤外線吸収法により測定した。From the obtained silicon nitride-based sintered body, a diameter of 1
A test piece of 0 mm × thickness 3 mm for measuring thermal conductivity and density and a 4-point bending test piece of 3 mm × 4 mm × 40 mm were collected. The density was determined from the results of dimensional measurement and weight measurement using a micrometer. The thermal conductivity was calculated by measuring the specific heat and the thermal diffusivity at room temperature by a laser flash method. Four-point bending strength is JIS R1 at room temperature
The measurement was performed according to 606. Further, the volume% of the silicon nitride particles was determined by eluting the grain boundary glass phase of the sintered body with hydrofluoric acid, individually taking out the silicon nitride particles, and performing SEM observation. In the present invention, the value of area% was evaluated as volume%. The aluminum content in the silicon nitride sintered body was measured by induction plasma emission spectrometry (abbreviated as ICP method), and the oxygen content was measured by infrared absorption method.
【００１６】本発明の窒化ケイ素質焼結体からなる熱交
換器用伝熱管１は、密度が９９．２％、常温における熱
伝導率が８５Ｗ／（ｍ・Ｋ）、常温における４点曲げ強
度が７２０ＭＰａであった。また、窒化ケイ素質焼結体
中のアルミニウムの含有量が０．０１重量％、酸素の含
有量が０．０１重量％、窒化ケイ素質焼結体中のβ型窒
化ケイ素粒子のうち短軸径が５μｍ以上のβ型窒化ケイ
素粒子の割合が２体積％であった。The heat exchanger tube 1 made of a silicon nitride sintered body of the present invention has a density of 99.2%, a thermal conductivity of 85 W / (m · K) at room temperature, and a four-point bending strength at room temperature. It was 720 MPa. The content of aluminum in the silicon nitride sintered body is 0.01% by weight, the content of oxygen is 0.01% by weight, and the minor axis diameter of β-type silicon nitride particles in the silicon nitride based sintered body is The ratio of β-type silicon nitride particles having a particle size of 5 μm or more was 2% by volume.
【００１７】また、本発明の窒化ケイ素質焼結体および
従来の伝熱管材料でもある比較例のサイアロン焼結体か
ら、直径６０ｍｍ×長さ２５ｍｍの試験片を採取し、各
試験片を８００℃に加熱した状態から０℃の水中に沈降
させる水中急冷試験を行った。その結果、サイアロン焼
結体の急冷面には亀甲羅状にき裂が発生したが、窒化ケ
イ素質焼結体の急冷面にはき裂は見られず、耐熱衝撃性
に優れることを確認できた。From the silicon nitride sintered body of the present invention and the sialon sintered body of the comparative example which is also a conventional heat transfer tube material, test pieces having a diameter of 60 mm and a length of 25 mm were collected, and each test piece was subjected to 800 ° C. A water quenching test was conducted in which the mixture was heated and settled in water at 0 ° C. As a result, cracks were formed on the quenched surface of the sialon sintered body in the form of a turtle shell, but no cracks were found on the quenched surface of the silicon nitride sintered body, confirming that it had excellent thermal shock resistance. Was.
【００１８】図２は本発明の窒化ケイ素質焼結体の熱応
答性試験に用いた管状体を示す。図２に示すように、本
発明の窒化ケイ素質焼結体からなる肉厚４ｍｍの管状体
７を作製した。管状体７は内径１８ｍｍ、外径２６ｍ
ｍ、長さ４５０ｍｍで片方の先端部が半球状に閉塞され
た形状である。この管状体７の中に、Ｋタイプの熱電対
８を挿入し、熱電対８の先端が管状体７の底面に当接す
るように支持体９により支持した。FIG. 2 shows a tubular body used for a thermal response test of the silicon nitride sintered body of the present invention. As shown in FIG. 2, a tubular body 7 having a thickness of 4 mm made of the silicon nitride sintered body of the present invention was produced. The tubular body 7 has an inner diameter of 18 mm and an outer diameter of 26 m
m, 450 mm in length, and one end is closed in a hemispherical shape. A K-type thermocouple 8 was inserted into the tubular body 7, and the thermocouple 8 was supported by the support 9 so that the tip of the thermocouple 8 was in contact with the bottom surface of the tubular body 7.
【００１９】そして、溶湯温度６２０℃、重量約３ｋｇ
の純アルミニウムの溶湯中に管状体７の閉塞された先端
部側を浸漬させて、熱電対８により溶湯の温度を測定し
た。図３は測温開始からの経過時間（秒）と温度（℃）
の結果を示す。本発明材では測温開始から約６０秒後に
２００℃、約１５０秒後に５００℃、約３９０秒後に６
２０℃になった。比較例のサイアロンを用いて管状体を
作製し同様の熱応答性試験を行ったところ、測温開始か
ら約６５秒後に２００℃、約１６０秒後に５００℃、約
４２０秒後に６２０℃になった。よって、本発明の窒化
ケイ素質焼結体はサイアロン焼結体に比べ、溶湯の熱が
管状体の表面を経て管状体内部の熱電対にまで速く到達
できた。本発明の窒化ケイ素質焼結体からなる熱交換器
用伝熱管は、この熱応答性試験の熱電対による測温にお
いて常温から２００℃に到達するまでの温度感知の最大
傾き、すなわち熱応答性を表わす最大感知速度が３℃／
秒以上であることが好ましい。Then, the molten metal temperature is 620 ° C. and the weight is about 3 kg.
The closed end portion of the tubular body 7 was immersed in a pure aluminum melt, and the temperature of the melt was measured by a thermocouple 8. Figure 3 shows the elapsed time (seconds) and temperature (° C) since the start of temperature measurement.
The result is shown. In the material of the present invention, 200 ° C. after about 60 seconds from the start of temperature measurement, 500 ° C. after about 150 seconds, and 6 ° C. after about 390 seconds.
The temperature reached 20 ° C. When a tubular body was prepared using the sialon of the comparative example and a similar thermal response test was performed, the temperature became 200 ° C. 65 seconds after the start of temperature measurement, 500 ° C. 160 seconds later, and 620 ° C. 420 seconds later. . Therefore, in the silicon nitride sintered body of the present invention, the heat of the molten metal was able to reach the thermocouple inside the tubular body through the surface of the tubular body faster than the sialon sintered body. The heat exchanger tube for a heat exchanger made of a silicon nitride sintered body of the present invention has a maximum slope of temperature sensing from normal temperature to 200 ° C. in a temperature measurement by a thermocouple in this thermal response test, that is, a thermal response. Maximum sensing speed is 3 ° C /
It is preferably at least seconds.
【００２０】本発明の熱交換器用伝熱管１を熱交換器に
組み込み、外表面を１０００℃以上の廃ガスに晒して熱
交換の使用に供したところ、従来の窒化ケイ素やサイア
ロン製の熱交換器用伝熱管に比べ熱伝達効率は格段に高
くなり、使用中の熱応力による割れやクラックも生じな
かった。When the heat exchanger tube 1 for a heat exchanger of the present invention is incorporated in a heat exchanger, and the outer surface is exposed to waste gas of 1000 ° C. or higher and used for heat exchange, the heat exchange tube made of conventional silicon nitride or sialon is used. The heat transfer efficiency was much higher than that of the dexterous heat transfer tube, and no cracks or cracks occurred due to thermal stress during use.
【００２１】[0021]
【発明の効果】本発明の熱交換器用伝熱管は熱伝導率が
高いため、伝熱管の表面から内部へ熱を迅速にかつ効率
よく伝達するので、伝熱管の表面と内部の温度差が緩和
され、熱応力による割れを防止できる。The heat transfer tube for a heat exchanger according to the present invention has a high thermal conductivity, so that heat is quickly and efficiently transferred from the surface of the heat transfer tube to the inside, so that the temperature difference between the surface and the inside of the heat transfer tube is reduced. Thus, cracking due to thermal stress can be prevented.
【図１】本発明実施例の熱交換器用伝熱管の概略断面図
を示す。FIG. 1 is a schematic sectional view of a heat exchanger tube for a heat exchanger according to an embodiment of the present invention.
【図２】熱応答性試験に用いた管状体の概略断面図を示
す。FIG. 2 is a schematic cross-sectional view of a tubular body used for a thermal response test.
【図３】熱応答性試験の測温開始からの経過時間と温度
の結果を示す。FIG. 3 shows the results of elapsed time and temperature from the start of temperature measurement in a thermal responsiveness test.
１ 熱交換器用伝熱管、 ２ 中空部、７ 管状体、
８ 熱電対、 ９ 支持体1 heat exchanger tube for heat exchanger, 2 hollow part, 7 tubular body,
8 thermocouple, 9 support
Claims (5)
結体からなる熱交換器用伝熱管であって、窒化ケイ素質
焼結体の常温における熱伝導率が７０Ｗ／（ｍ・Ｋ）以
上であることを特徴とする熱交換器用伝熱管。1. A heat exchanger tube for a heat exchanger comprising a silicon nitride sintered body containing silicon nitride as a main component, wherein the silicon nitride sintered body has a thermal conductivity at room temperature of 70 W / (m · K) or more. A heat exchanger tube for a heat exchanger.
曲げ強度が６００ＭＰａ以上であることを特徴とする請
求項１に記載の熱交換器用伝熱管。2. The heat transfer tube for a heat exchanger according to claim 1, wherein the silicon nitride sintered body has a four-point bending strength at room temperature of 600 MPa or more.
含有量が０．２重量％以下であることを特徴とする請求
項１または２に記載の熱交換器用伝熱管。3. The heat exchanger tube for a heat exchanger according to claim 1, wherein the content of aluminum in the silicon nitride based sintered body is 0.2% by weight or less.
３．０重量％以下であることを特徴とする請求項１〜３
のいずれかに記載の熱交換器用伝熱管。4. The silicon nitride sintered body according to claim 1, wherein the oxygen content is 3.0% by weight or less.
The heat exchanger tube for a heat exchanger according to any one of the above.
ｍｍ以上の管状体に熱電対を挿入し、熱電対の先端を管
状体の底面に当接させて、この管状体を溶湯に浸漬させ
て熱電対による測温したとき常温から２００℃に到達す
るまでの温度感知の最大傾きが３℃／秒以上であること
を特徴とする請求項１〜４のいずれかに記載の熱交換器
用伝熱管。5. A thickness 4 made of the silicon nitride sintered body.
When a thermocouple is inserted into a tubular body of not less than mm, the tip of the thermocouple is brought into contact with the bottom surface of the tubular body, the tubular body is immersed in a molten metal, and reaches 200 ° C. from room temperature when the temperature is measured by the thermocouple. The heat transfer tube for a heat exchanger according to any one of claims 1 to 4, wherein the maximum gradient of the temperature sensing up to 3 ° C / sec is 3 ° C / sec or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001090388A JP2002286397A (en) | 2001-03-27 | 2001-03-27 | Heat transfer tube for heat exchanger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001090388A JP2002286397A (en) | 2001-03-27 | 2001-03-27 | Heat transfer tube for heat exchanger |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002286397A true JP2002286397A (en) | 2002-10-03 |
Family
ID=18945178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001090388A Pending JP2002286397A (en) | 2001-03-27 | 2001-03-27 | Heat transfer tube for heat exchanger |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2002286397A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8210999B2 (en) * | 2003-12-11 | 2012-07-03 | Hitachi Metals Ltd. | Roll for use in galvanizing pot |
| CN111774841A (en) * | 2020-09-07 | 2020-10-16 | 山东东研智能科技有限公司 | Intelligent automatic pipe penetrating machine for heat exchanger pipe bundle |
-
2001
- 2001-03-27 JP JP2001090388A patent/JP2002286397A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8210999B2 (en) * | 2003-12-11 | 2012-07-03 | Hitachi Metals Ltd. | Roll for use in galvanizing pot |
| CN111774841A (en) * | 2020-09-07 | 2020-10-16 | 山东东研智能科技有限公司 | Intelligent automatic pipe penetrating machine for heat exchanger pipe bundle |
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