WO2000077450A1 - Radiateurs a combustion superficielle et panneaux radiants associes - Google Patents

Radiateurs a combustion superficielle et panneaux radiants associes Download PDF

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Publication number
WO2000077450A1
WO2000077450A1 PCT/GB2000/002075 GB0002075W WO0077450A1 WO 2000077450 A1 WO2000077450 A1 WO 2000077450A1 GB 0002075 W GB0002075 W GB 0002075W WO 0077450 A1 WO0077450 A1 WO 0077450A1
Authority
WO
WIPO (PCT)
Prior art keywords
plaque
surface combustion
fibres
combustion radiant
plaques
Prior art date
Application number
PCT/GB2000/002075
Other languages
English (en)
Inventor
Lindsay John Harold Todd
Jane Miller
Original Assignee
The Morgan Crucible Company Plc
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 The Morgan Crucible Company Plc filed Critical The Morgan Crucible Company Plc
Priority to AU50903/00A priority Critical patent/AU5090300A/en
Publication of WO2000077450A1 publication Critical patent/WO2000077450A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/12—Radiant burners
    • F23D14/14—Radiant burners using screens or perforated plates
    • F23D14/145—Radiant burners using screens or perforated plates combustion being stabilised at a screen or a perforated plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2203/00—Gaseous fuel burners
    • F23D2203/10—Flame diffusing means
    • F23D2203/102—Flame diffusing means using perforated plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2212/00—Burner material specifications
    • F23D2212/10—Burner material specifications ceramic
    • F23D2212/103—Fibres

Definitions

  • This invention relates to surface combustion radiant heaters and heating plaques.
  • Surface combustion radiant heaters comprise a plaque mounted on a burner box.
  • a gas/air mixture supplied to the burner box passes through a plurality of ports in the plaque and bums at the outer surface of the plaque.
  • the burning gases raise the temperature of the outer surface of the plaque so that it radiates heat and light.
  • Plaques of this type are described, for example, in UK Patent No. 1436842.
  • UK Patent No. 1436842 describes the benefits of using as the material of the plaque an open structure of bonded refractory ceramic fibre, the continuous service temperature of fibre and bonding agent being at least 1000°C. Reference to UK Patent No. 1436842 may be had in the event of any further explanation of the manufacture of plaques being required.
  • Such surface combustion radiant heaters are used in a variety of applications including industrial heating and domestic heating.
  • For domestic heating the visual appearance of plaques may be modified by surface decoration.
  • the plaques are made from an inorganic bonded fibrous material.
  • the fibres used are usually alumino-silicate fibres.
  • An alternative type of plaque uses a body of non-fibrous dense ceramic (e.g. cordierite or mullite) or a body of low density ceramic (e.g. amorphous silica) and such plaques frequently have a higher luminance than fibrous plaques.
  • Surface combustion burner plaques can fail however if the flame can pass back through the ports to the burner box behind the plaque ("lightback").
  • Fibrous plaques because of their lower thermal conductivity, are less susceptible to failure through lightback and so permit higher throughputs of gas.
  • the present invention provides a surface combustion radiant heating plaque formed from an inorganic bonded fibrous material in which the fibres are alkaline earth silicate fibres.
  • Alkaline earth silicate fibres are described for example in WO87/05007, WO89/12032, WO93/15028, WO94/15883, WO96/02478, WO97/16386 and WO97/49643.
  • the fibres are calcium magnesium silicate fibres.
  • the alkaline earth silicate fibres have a composition comprising CaO, SiO 2 , MgO, optionally ZrO 2 , optionally less than 0.75mol% Al 2 O , any incidental impurities amounting to less than 2mol% in total, in which the amount of CaO is less than the sum of the amount of MgO and twice the amount of ZrO 2 and in which the SiO 2 excess (defined as the amount of SiO 2 calculated as remaining after the above named constituents are crystallised as silicates) exceeds 21.8mol%.
  • Such fibres are described in WO94/15883 and reference to this patent should be made for any further explanation of the term "SiO 2 excess" required.
  • the fibres may have a composition comprising in weight percent:-
  • compositions comprise in weight percent:-
  • An alternative calcium magnesium silicate fibre is one in which the amount of MgO in mol% is greater than the amount of CaO in mol % and which comprises:-
  • MgO ⁇ 17 wt% and which preferably comprises
  • the plaques may be formed by vacuum casting the fibre, a filler, and optionally a flux to fuse the fibres.
  • a starch for green body handling strength may be used.
  • the slurry may comprise:-
  • the plaque may be formed from a slurry comprising in weight percent of the stated ingredients:-
  • the invention also extends to surface combustion radiant heaters comprising a surface combustion radiant heating plaque formed from an inorganic bonded fibrous material in which the fibres are alkaline earth silicate fibres.
  • Fig. 1 is a graph comparing radiant output v. input for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 2 is a graph comparing radiant output v. fuel/gas stoichiometry for a plaque in accordance with the invention and a comparison conventional plaque
  • Fig. 3 is a graph comparing radiant efficiency v. port loading for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 4 is a graph comparing true NO x output v. port loading for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 5 is a graph comparing true NO x output v. air/fuel stoichiometry for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig 6 is a graph comparing CO/CO 2 ratio v. input for a plaque in accordance with the invention and a comparison conventional plaque; 7 __. 8 _ u ⁇ ' ⁇ Il . l » L ⁇ -,
  • Fig. 7 is a graph comparing CO/CO 2 ratio v. air/fuel stoichiometry for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 8 is a graph comparing luminance v. input for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 9 is a chromaticity diagram comparing colour v. input for a plaque in accordance with the invention and a comparison conventional plaque;
  • Fig. 10 is a more detailed chromaticity diagram than in Fig.9 comparing colour v. input for a plaque in accordance with the invention and a comparison conventional plaque.
  • a pair of plaques of identical port diameters, radiant areas and.size were made.
  • the burning area and average port dimensions of the plaques were measured using a VIEW 1200 non-contact co-ordinate measuring machine to ensure comparability of the data but the two plaques tested were identical as far as measured and so normalisation of data was not required.
  • the plaques had a total burning area of 11212 mm 2 , with 909 ports of port diameter 1.44mm making up a total port area of 1481mm 2 .
  • the burning area is defined as the area over which the plaque is lit, that is to say the area of a boundary encompassing all of the ports at which gas is burned.
  • the first plaque (A) was made in accordance with the present invention using Superwool 612TM refractory ceramic fibre which is available from Thermal Ceramics de France SA or Thermal Ceramics Limited.
  • Superwool 612TM has a nominal composition (by weight) of SiO 2 64%, CaO 17%, MgO 13.5%, ZrO 2 5%, and impurities ⁇ 0.5%, and is usable at temperatures in excess of 1200°C and up to 1250°C.
  • the second plaque (B) was made for comparison purposes from KaowoolTM fibre which has a composition approximately 46% Al 2 O 3 , 54% SiO 2 .
  • the plaques were formed by vacuum deposition from a slurry.
  • the compositions used in making the slurry were as follows (weight percent):-
  • the filler used was Speswhite clay but other fillers such as talc may be used.
  • Boron phosphate was used as a flux but other fluxes (e.g. borax) may be used.
  • the amount of boron phosphate is less than in the conventional mix since it was found that the flux (which acts as a sintering agent to cross-link the fibres) reacts more strongly with alkaline earth metal silicate fibres than with conventional alumino-silicate fibres and at conventional levels a higher shrinkage than desirable resulted. Comparative tests at various levels of boron phosphate were done (keeping the fibre/filler ratio constant) and the results are indicated in Table 1 below:-
  • the level used in plaque (A) was chosen as a compromise to give sufficient hardness with low shrinkage but the invention is not limited to this low level. Higher levels may be appropriate in some circumstances.
  • the slurries were prepared by adding successively the fibre, the filler, the boron phosphate and then the cationic starch to water while agitating.
  • the materials were added at a rate of approximately 60kg of fibre plus filler plus boron phosphate in total to a cubic metre of water.
  • the slurries were vacuum formed onto a perforated expanded copper grid having aperure size of a nominal 0.5mm as measured by travelling microscope.
  • the former had retractable pins to produce the ports in the finished plaque.
  • the resultant green shape was dried and then fired in air at about 1050°C for about 40 minutes, sufficient to bond the fibres.
  • Table 2 and Figs. 1- 3 show that radiant output and efficiency of the plaques were very similar over a range of inputs and at different gas mixture stoichiometries.
  • the column headed input represents the calorific value of the gas supplied divided by the burning area of the plaque (the area which contains ports); port loading represents the calorific value of the gas supplied divided by the area of the ports; stoichiometry represents the percentage amount of air required for complete combustion - 100 representing complete combustion, percentages below this indicating a fuel rich mixture and percentages above indicating an air rich (also known as fuel lean) mixture; total output represents the radiant heat output of the plaque; relative output represents the output per unit area of burning area of plaque; and efficiency is the ratio of radiant heat output to the input.
  • the deficiency between the amount of radiant heat and the heat input is accounted for partly by heating of the combustion gases (which results in convective heat) and partly by loss of energy in light emission, sound, latent heat, and other forms of energy.
  • Table 3 and Figs. 4-7 show that the production of combustion products are broadly comparable between the plaques.
  • the columns headed input, port loading, and stoichiometry are as in Table 2; true NOx represents a measured value for nitrogen oxides which is corrected for dilution by calculation; CO represents the amount of carbon monoxide measured in volume percent; CO 2 represents the amount of carbon dioxide measured in volume percent; and ratio CO/C0 2 is their ratio.
  • Table 4 and Figs. 8-10 shows that there are real differences in the brightness and colour of the plaques.
  • Table 4 the columns headed input, port loading, and stoichiometry are as in Table 2; luminance is the light output in candelas per square metre of the burning area; co-ordinates x and y are chromaticity co-ordinates indicative of colour.
  • An explanation of colour co-ordinates may be found at pages 84-87 of "Colour physics for industry", Ed. Roderick McDonald, published 1987 by the society of Dyers and Colourists. In the present case, because we are concerned with light output rather than reflected light, complications such as requiring standard observing conditions and a standard light source are removed.
  • the chromaticity co-ordinates were measured using a Bentham Spectrophotometer TM 300 series monochromator which measures the light output at a stepped series of frequencies and has software to calculate the x and y chromaticity co-ordinates directly.
  • the spectrophotometer was calibrated with a lamp of the integrating sphere design traceable to National Physical Laboratory standards.
  • the plaque in accordance with the invention was significantly brighter at the inputs tested (see Fig. 8) and also exhibited much more intense colour at equivalent input levels (see Figs. 9 and 10).
  • the plaque in accordance with the invention is comparable with a conventional plaque, at higher inputs the inventive plaque has a considerably higher luminance (over twice as high at an input of 250 kW/m 2 ).
  • the plaque has a luminance in excess of 75cd/m 2 when supplied with a 100% stoichiometry air/methane mixture at an input of 170 kW/m and has a luminance in excess of 200c ⁇ Vm 2 when supplied with a 100% stoichiometry air/methane mixture at an input of 250 kW/m 2 . This is well in excess of a conventional plaque.
  • a plaque which has a luminance in excess of 90cd m 2 when supplied with a 100% stoichiometry air/methane mixture at an input of 170 kW/m and has a luminance in excess of 220cd/m 2 when supplied with a 100% stoichiometry air/methane mixture at an input of 250 kW/m 2 is dramatically better than conventional fibrous plaques.
  • Most non- fibrous plaques cannot provide an input of 250 kW/m 2 when supplied with a 100% stoichiometry air/methane mixture as failure through lightback occurs at such high inputs.
  • a plaque in accordance with this invention could go to inputs as high as 400 kW/m 2 and maintain radiant mode.
  • a chromaticity diagram is shown as to CIE 1931.
  • a curved boundary with one straight edge is shown. Towards the edge of the area indicated by this boundary lay intense colours whereas towards the centre lay pale colours and white. As one moves along the curved boundary the colours change from red through yellow and green to blue. (This curve is called the spectrum locus).
  • Fig. 10 is a more detailed view showing linked pairs of points representing a conventional plaque and a plaque in accordance with the invention at various inputs (shown unlinked in Fig. 9). The pairs of points plotted on this graph show that at all inputs the inventive plaque has a stronger colour than the conventional plaque, lying further from the centre of the area indicated and towards the spectrum locus. Since the overall radiant output of the two plaques is similar, as measured using a broadband thermopile, it appears that the emissivity in the visual part of the spectrum is greater for the inventive plaque than a conventional plaque.
  • the plaques in accordance with the present invention emit a more yellow light than the conventional plaques.
  • the eye is most sensitive in the yellow region of the spectrum a strong yellow colour looks brighter and warmer than an orange or red colour.
  • the present invention therefore provides a surface combustion radiant heating plaque having a higher luminance and stronger colour than conventional plaques with broadly similar combustion properties.
  • Such plaques are particularly useful in domestic heating but may be used in any application where conventional plaques are used.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Glass Compositions (AREA)

Abstract

L'invention porte sur un panneau radiant à combustion superficielle formé d'un matériau de fibres minérales liées de silicate de métal alcalino-terreux. Lesdits panneaux ont une luminance plus élevée et une coloration plus forte que les panneaux classiques, et des propriétés de combustion sensiblement identiques.
PCT/GB2000/002075 1999-06-11 2000-05-30 Radiateurs a combustion superficielle et panneaux radiants associes WO2000077450A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU50903/00A AU5090300A (en) 1999-06-11 2000-05-30 Surface combustion radiant heaters and heating plaques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9913681A GB2347490B (en) 1999-06-11 1999-06-11 Surface combustion radiant heaters and heating plaques
GB9913681.4 1999-06-11

Publications (1)

Publication Number Publication Date
WO2000077450A1 true WO2000077450A1 (fr) 2000-12-21

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Family Applications (1)

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PCT/GB2000/002075 WO2000077450A1 (fr) 1999-06-11 2000-05-30 Radiateurs a combustion superficielle et panneaux radiants associes

Country Status (3)

Country Link
AU (1) AU5090300A (fr)
GB (1) GB2347490B (fr)
WO (1) WO2000077450A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1364162A1 (fr) * 2001-03-02 2003-11-26 Marsden, Inc. Generation d'infrarouge

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3954387A (en) * 1972-06-08 1976-05-04 J. Tennant & Sons (Warrington) Limited Burners
GB1436842A (en) 1972-06-08 1976-05-26 Tennant & Sons Warrington Ltd Radiant gas-fired burner
WO1987005007A1 (fr) 1986-02-20 1987-08-27 Manville Corporation COMPOSITION DE FIBRES INORGANIQUES CONSISTANT ESSENTIELLEMENT EN Al2O3, MgO, CaO et SiO2
WO1989012032A2 (fr) 1988-06-01 1989-12-14 Manville Sales Corporation Procede pour decomposer une fibre inorganique
WO1993015028A1 (fr) 1992-01-17 1993-08-05 The Morgan Crucible Company Plc Fibres inorganiques, solubles en solution saline
WO1994015883A1 (fr) 1993-01-15 1994-07-21 The Morgan Crucible Company Plc Fibres solubres inorganiques salines
US5447666A (en) * 1992-05-20 1995-09-05 Canadian Gas Research Institute Method of forming radiant fiber burner
WO1996002478A1 (fr) 1994-07-13 1996-02-01 The Morgan Crucible Company Plc Fibres inorganiques solubles en solution saline
WO1997016386A1 (fr) 1995-10-30 1997-05-09 Unifrax Corporation Fibre de verre resistant aux hautes temperatures
WO1997049643A1 (fr) 1996-06-21 1997-12-31 The Morgan Crucible Company Plc Fibres inorganiques salines et solubles
US5749721A (en) * 1993-07-22 1998-05-12 Gossler Thermal Ceramics Gmbh Ceramic combustion support element for surface burners and process for producing the same

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3954387A (en) * 1972-06-08 1976-05-04 J. Tennant & Sons (Warrington) Limited Burners
GB1436842A (en) 1972-06-08 1976-05-26 Tennant & Sons Warrington Ltd Radiant gas-fired burner
WO1987005007A1 (fr) 1986-02-20 1987-08-27 Manville Corporation COMPOSITION DE FIBRES INORGANIQUES CONSISTANT ESSENTIELLEMENT EN Al2O3, MgO, CaO et SiO2
WO1989012032A2 (fr) 1988-06-01 1989-12-14 Manville Sales Corporation Procede pour decomposer une fibre inorganique
WO1993015028A1 (fr) 1992-01-17 1993-08-05 The Morgan Crucible Company Plc Fibres inorganiques, solubles en solution saline
US5447666A (en) * 1992-05-20 1995-09-05 Canadian Gas Research Institute Method of forming radiant fiber burner
WO1994015883A1 (fr) 1993-01-15 1994-07-21 The Morgan Crucible Company Plc Fibres solubres inorganiques salines
US5749721A (en) * 1993-07-22 1998-05-12 Gossler Thermal Ceramics Gmbh Ceramic combustion support element for surface burners and process for producing the same
WO1996002478A1 (fr) 1994-07-13 1996-02-01 The Morgan Crucible Company Plc Fibres inorganiques solubles en solution saline
WO1997016386A1 (fr) 1995-10-30 1997-05-09 Unifrax Corporation Fibre de verre resistant aux hautes temperatures
WO1997049643A1 (fr) 1996-06-21 1997-12-31 The Morgan Crucible Company Plc Fibres inorganiques salines et solubles

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1364162A1 (fr) * 2001-03-02 2003-11-26 Marsden, Inc. Generation d'infrarouge
EP1364162A4 (fr) * 2001-03-02 2006-04-05 Marsden Inc Generation d'infrarouge

Also Published As

Publication number Publication date
GB2347490B (en) 2001-03-07
AU5090300A (en) 2001-01-02
GB2347490A (en) 2000-09-06
GB9913681D0 (en) 1999-08-11

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