EP0248674A1 - Paneel zur Wärmeisolierung - Google Patents

Paneel zur Wärmeisolierung Download PDF

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Publication number
EP0248674A1
EP0248674A1 EP87304993A EP87304993A EP0248674A1 EP 0248674 A1 EP0248674 A1 EP 0248674A1 EP 87304993 A EP87304993 A EP 87304993A EP 87304993 A EP87304993 A EP 87304993A EP 0248674 A1 EP0248674 A1 EP 0248674A1
Authority
EP
European Patent Office
Prior art keywords
panel
heat insulating
membrane
ceramic
layers
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.)
Withdrawn
Application number
EP87304993A
Other languages
English (en)
French (fr)
Inventor
William Robert Laws
Geoffrey Ronald Reed
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Encomech Engineering Services Ltd
Original Assignee
Encomech Engineering Services Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Encomech Engineering Services Ltd filed Critical Encomech Engineering Services Ltd
Publication of EP0248674A1 publication Critical patent/EP0248674A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
    • F27D1/0009—Comprising ceramic fibre elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0033—Linings or walls comprising heat shields, e.g. heat shieldsd
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/04—Casings; Linings; Walls; Roofs characterised by the form, e.g. shape of the bricks or blocks used
    • F27D1/06—Composite bricks or blocks, e.g. panels, modules

Definitions

  • This invention relates to heat insulating panels for high temperature applications, e.g. as heat shields in hot rolling mills and as walls of furnaces.
  • High temperature ceramic fibre insulation enables more compact furnace walls to be constructed because of its low thermal conductivity compared with traditional refractory bricks. To facilitate installation it is common practice to build ceramic fibre furnace walls with individual panels or with overlapping layers of ceramic fibre blanket held in place with studs. While this form of insulation is considerably better than conventional refractories in the form of brick, it is found however that it loses some of its relative advantage at higher temperatures, e.g. greater than about 800°C.
  • Panels comprising a ceramic fibre core have also found a useful application as heat shields arranged to surround lengths of hot metal being processed so as to prevent heat loss during transport and working of the metal.
  • heat shields arranged to surround lengths of hot metal being processed so as to prevent heat loss during transport and working of the metal.
  • a major loss of heat occurs while the hot transfer bar is on the roller table between the roughing mill and the finishing mills.
  • Close-fitting insulating tunnels (see e.g. GB 1603428) using insulating ceramic and fibre panels with metal membranes have been developed specifically to reduce the heat loss in such circumstances.
  • These heat shield panels provide fairly effective heat insulation in transient operations, i.e. when hot material is rolled with gap times of several minutes between successive transfer bars, but if the gap time is reduced to such an extent that the internal temperature in the panels rises excessively, as in the case of a high temperature furnace, there is a loss of efficiency.
  • the table that follows indicates the increase in thermal conductivity that can occur at very high temperatures in different insulating materials:
  • the first three lines of the table show conductivity values for solid insulating bricks of silica (SiO2), of alumina (Al2O3), and of a mixture of these two substances.
  • Ceramic fibres are typically made from the same substances or a mixture of the two and there follow examples of two different grades of ceramic fibre composed of 50% silica and 50% alumina.
  • the final line of the table gives conductivity values for still air.
  • the present invention is aimed at improving the construction of ceramic fibre heat-insulating panels so as to mitigate the increase of conductivity of the fibre material at high temperature and so reduce the heat loss of such panels.
  • a heat insulating panel comprising a plurality of layers of ceramic fibre insulating material with a metallic membrane interposed between the ceramic fibre layers or at least two said layers.
  • a metallic membrane interposed between the ceramic fibre layers or at least two said layers.
  • the invention is based on studies which show that, to a small extent, there is an increase of heat loss through a ceramic fibre material above 1000°C due to convection in the air-filled voids, but the main cause of heat loss is the transmission of radiant heat along the fibres themselves due to their transparency to radiation in the near infra-red and visible range. In fact, a property which has been exploited usefully in optical fibre applications hinders the effective use of ceramic fibres as a high temperature insulating material.
  • the presence of a metal membrane at the hot face of a panel inhibits the passage of energy in the shorter wavelengths to the ceramic fibre core, and the thermal shock of rapid heating is taken by the metal membrane.
  • the membrane modifies the radiant energy so that energy of longer wavelengths passes into the ceramic fibre core.
  • the lengthening of wavelengths avoids significant heat loss by transmission of radiation through the fibres, but if the hot face of the panel is subjected to a high temperature for some period of time, the temperature of the membrane comes close to that of the hot material. Radiant heat losses through the ceramic fibres then increase.
  • the or each membrane can act as a radiation barrier so that the benefits obtained by use of the hot face membrane in the immediate transient condition are extended and it is also possible to obtain some advantage even under steady state conditions.
  • the hot face of a panel according to the invention may be formed by a membrane of a high-temperature alloy.
  • a ceramic coating laid directly onto the ceramic fibre e.g. by spraying. This may, for example, take the form of a glazed coating.
  • the or at least one interposed membrane should have a reflective surface facing towards the hot face of the panel.
  • a reflective aluminium sheet may form the interposed membrane or an outer one or more of the interposed membranes.
  • this illustrates the progressive shift of the wavelength distribution of the radiated heat from metal components at different temperatures, the peak occuring at progressively shorter wavelengths as the temperature of the component rises.
  • a transfer bar at a typical temperature of 1050°C shows a peak below the 2.5 micron wavelength that is effectively an upper limit to the transparency of current ceramic fibres.
  • a heat shield panel having an outer metallic membrane facing onto the hot transfer bar might have that membrane at a temperature of 1000°C; the graph shows a slight increase in the peak radiation wavelength but it is notable that a substantial portion of the total heat radiation still occurs below the 2.5 micron limit. Only at substantially lower temperatures, such as the 700°C example also shown, does the wavelength peak drift much above that limit to give a marked drop in the proportion of energy radiated at shorter wavelengths.
  • the graph thus indicates how the outer metal membrane forming the hot face of a heat shield panel can quickly lose its effectiveness if it is exposed to a hot transfer bar long enough for the panel to reach steady state conditions.
  • a heat shield panel is shown in which, in addition to the hot face membrane 2 there are two further metallic membranes 4, 6 within the thickness of the panel, interposed between appropriately graded layers of ceramic fibre insulation 8, 10, 12.
  • the second and third membranes 4, 6 are able to modify the wavelengths of energy radiation through them from the hotter side of the panel, spreading the radiant flux to a longer mean wavelength, so as to improve the efficiency of operation of ceramic fibre layers.
  • the particular materials chosen for the membranes will depend upon the actual temperature conditions under which the panel is intended to operate.
  • the hot face membrane 2, and, in normal circumstances the membrane 4 behind it, will be of high temperature alloy. The material will be more effective if it remains reflective at the temperatures encountered, but the high cost of the materials having this capability at very high temperatures may militate against their use.
  • the second internal membrane 6 is made of aluminium foil.
  • the membrane must be placed at a position at which its temperature will be safely below the material melting point, i.e. preferably not more than 550°C.
  • the internal membranes of the panel described thus act as successive radiation barriers.
  • the panel is given an improved insulating performance under transient conditions and there is a reduction in the steady state heat loss when the hot face is exposed to very high temperatures.
  • Such constructions of panel can be applied in a wide variety of high temperature uses, e.g. in hot metal processing such as for rolling mill transfer table heat shields, and also in furnaces and ovens.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Laminated Bodies (AREA)
EP87304993A 1986-06-06 1987-06-05 Paneel zur Wärmeisolierung Withdrawn EP0248674A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB868613841A GB8613841D0 (en) 1986-06-06 1986-06-06 Heat insulating panels
GB8613841 1986-06-06

Publications (1)

Publication Number Publication Date
EP0248674A1 true EP0248674A1 (de) 1987-12-09

Family

ID=10599080

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87304993A Withdrawn EP0248674A1 (de) 1986-06-06 1987-06-05 Paneel zur Wärmeisolierung

Country Status (2)

Country Link
EP (1) EP0248674A1 (de)
GB (1) GB8613841D0 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0329378A2 (de) * 1988-02-15 1989-08-23 Research Development Corporation of Japan Vakuumofen für thermische Behandlungen
FR2630533A1 (fr) * 1988-04-25 1989-10-27 Clecim Sa Enceinte thermique
FR2660060A1 (fr) * 1990-03-23 1991-09-27 Sarp Ind Enceinte thermique destinee a fonctionner a temperature elevee.
WO1993013894A1 (en) * 1992-01-08 1993-07-22 Richards Engineering Limited Incineration apparatus
DE102015212976A1 (de) 2015-07-10 2017-01-12 Sms Group Gmbh Wärmedämmvorrichtung
DE102022203635A1 (de) 2022-04-11 2023-10-12 Sms Group Gmbh Reflektorelement für eine Wärmedämmhaube

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3540171A (en) * 1968-06-18 1970-11-17 Republic Steel Corp Insulated cover for steel storage and thermal control
FR96601E (fr) * 1962-09-03 1973-07-20 Henri Horaist Perfectionnements aux fours industriels.
FR2415784A2 (fr) * 1978-01-30 1979-08-24 Petroles Cie Techniques Nouveaux elements modulaires pour constitution de voutes en fibres ceramiques
GB2109903A (en) * 1981-09-16 1983-06-08 Clinotherm Ltd Improvements in furnace insulation
US4595358A (en) * 1985-04-26 1986-06-17 Wean United, Inc. Re-radiating heat shield

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR96601E (fr) * 1962-09-03 1973-07-20 Henri Horaist Perfectionnements aux fours industriels.
US3540171A (en) * 1968-06-18 1970-11-17 Republic Steel Corp Insulated cover for steel storage and thermal control
FR2415784A2 (fr) * 1978-01-30 1979-08-24 Petroles Cie Techniques Nouveaux elements modulaires pour constitution de voutes en fibres ceramiques
GB2109903A (en) * 1981-09-16 1983-06-08 Clinotherm Ltd Improvements in furnace insulation
US4595358A (en) * 1985-04-26 1986-06-17 Wean United, Inc. Re-radiating heat shield

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0329378A2 (de) * 1988-02-15 1989-08-23 Research Development Corporation of Japan Vakuumofen für thermische Behandlungen
EP0329378A3 (en) * 1988-02-15 1990-10-03 Research Development Corporation Of Japan Vacuum heat treating furnace
FR2630533A1 (fr) * 1988-04-25 1989-10-27 Clecim Sa Enceinte thermique
FR2660060A1 (fr) * 1990-03-23 1991-09-27 Sarp Ind Enceinte thermique destinee a fonctionner a temperature elevee.
WO1993013894A1 (en) * 1992-01-08 1993-07-22 Richards Engineering Limited Incineration apparatus
US5452669A (en) * 1992-01-08 1995-09-26 Richards Engineering Limited Incineration apparatus
DE102015212976A1 (de) 2015-07-10 2017-01-12 Sms Group Gmbh Wärmedämmvorrichtung
WO2017009074A1 (de) 2015-07-10 2017-01-19 Sms Group Gmbh Wärmedämmvorrichtung
US11318512B2 (en) 2015-07-10 2022-05-03 Sms Group Gmbh Thermal insulation device
DE102022203635A1 (de) 2022-04-11 2023-10-12 Sms Group Gmbh Reflektorelement für eine Wärmedämmhaube
WO2023198475A1 (de) 2022-04-11 2023-10-19 Sms Group Gmbh Reflektorelement für eine wärmedämmhaube

Also Published As

Publication number Publication date
GB8613841D0 (en) 1986-07-09

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Inventor name: REED, GEOFFREY RONALD

Inventor name: LAWS, WILLIAM ROBERT