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1. EP2731918 - GLASS-MELTING EQUIPMENT AND PROCESS

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Claims

1. Method for melting glass in a melting furnace,

• said method using

i. a first oxidant chosen from air and oxygen-enriched air and

ii. a second oxidant having a content in oxygen from 80% vol. to 100% vol., preferably from 90% vol. to 100% vol.,

the content in oxygen of the second oxidant being higher than the content in oxygen of the first oxidant,

• the melting furnace comprising:

i. a melting chamber provided with n burners for the combustion of a fuel in the chamber, said n burners generating thermal energy and a hot stream of fumes having a temperature at the outlet of the chamber from 1000°C to 1600°C, with n ≥ 1, m of said n burners being first burners, with 1 ≤ m ≤ n, and

ii. a preheating equipment,

method wherein:

• solid raw material is melted in the melting chamber with the obtaining of melted glass,

• the hot stream of fumes coming from the chamber is introduced into the preheating equipment,

• a stream of a heat transfer fluid is heated by heat exchange with the hot stream of the fumes in a first heat exchanger of the preheating equipment in such a way as to generate a cold stream of the fumes and a heated stream of the heat transfer fluid having a temperature from 600°C to 900°C,

and wherein:

• in a first phase of the method:

- the first oxidant is used as a heat transfer fluid, and

- a stream of the second oxidant is preheated in a second heat exchanger of the preheating equipment by heat exchange with the heated stream of the heat transfer fluid in such a way as to generate a preheated stream of the second oxidant having a temperature from 400°C to 650°C and a tempered stream of the heat transfer fluid having a temperature from 350°C to 650°C,

- a flow DO1 of the preheated stream of the second oxidant is supplied to the m first burners as an oxidiser, with DO1 > 0 Nm3,

the method being characterised in that:

• in a second phase:

- a flow DO2 of the second oxidant and a flow DA2 of the first oxidant are supplied to the m first burners as oxidisers, with DO1 > DO2 > 0 Nm3 and DA2 > 0 Nm3

- the flow DA2 of the first oxidant is supplied to the m first burners in the form of a corresponding portion of the heated stream of the heat transfer fluid,

- the flow DO2 of the second oxidant is supplied to the m first burners:

∘ entirely separately from the flow DA2 of the first oxidant, or

∘ entirely in a mixture with the flow DA2 of the first oxidant, or

∘ partially mixed with the flow DA2 of the first oxidant and partially separately from the flow DA2 of the first oxidant,

in such a way that:

i. when the flow DO2 of the second oxidant is partially or totally mixed with the first oxidant upstream from the first heat exchanger of the preheating equipment, the mixture thus obtained is used as a heat transfer fluid and,

ii. when the flow DO2 of the second oxidant is not mixed with the flow DA2 of the first oxidant upstream from the first heat exchanger but only partially or totally downstream from the first heat exchanger or not at all, the first oxidant is used as a heat transfer fluid.


  2. Method according to claim 1, wherein the content in oxygen of the first oxidant is between 21% vol. and 40% vol.
  3. Method according to claim 2, wherein the content in oxygen of the first oxidant is between 21% vol. and 25% vol.
  4. Method according to claim 1, wherein the content in oxygen of the first oxidant is from 40% vol. to 90% vol.
  5. Method according to any one of the preceding claims, wherein the melting furnace is a furnace with longitudinal burners or a furnace with cross-fire burners.
  6. Method according to any one of the preceding claims, wherein m = n.
  7. Method according to any one of the preceding claims, wherein use is made of the preheating equipment to also preheat the fuel upstream from the melting chamber.
  8. Equipment for melting glass comprising:

• a supply unit comprising:

i. a source of fuel (10),

ii. a first source (20) of a first oxidant that consists of air or of oxygen-enriched air,

iii. a second source (30) of a second oxidant having a content in oxygen from 80% vol. to 100% vol., preferably from 90% vol. to 100% vol., and higher than the content in oxygen of the first oxidant,

• a melting furnace comprising:

i. a melting chamber (100) provided with n burners for the combustion of a fuel with the generation of thermal energy and a hot stream of fumes inside the chamber (100), with n ≥ 1, the melting chamber (100) also comprising an outlet of fumes (120120) for the evacuation from the chamber of the hot stream of fumes,

ii. a preheating equipment (210, 220),

• a network of pipes connecting the supply unit (10, 20, 30), the preheating equipment (210, 220) and the melting chamber (100),

equipment for melting wherein:

• m of the n burners are first burners (110), with 1 ≤ m ≤ n, and

• the preheating equipment comprises:

i. a first heat exchanger (210) for the heating of a stream of a heat transfer fluid containing the first oxidant by heat exchange with the hot stream of fumes, the network of pipes connecting the outlet of fumes (120120) of the melting chamber (100) to an inlet of the hot stream of fumes of said first heat exchanger (210) and connecting the first source (20) to an inlet of heat transfer fluid to be heated of said first heat exchanger (210),

ii. a second heat exchanger (220) for the preheating of a stream of the second oxidant by heat exchange with the heated stream of heat transfer fluid, the network of pipes connecting the second source (30) with an inlet of the second oxidant of the second exchanger (220), connecting an outlet of heated stream of heat transfer fluid of the first heat exchanger (210) with an inlet of heated stream of heat transfer fluid of the second heat exchanger (220) and connecting an outlet of a hot stream of second oxidant of the second heat exchanger (220) with an inlet of oxidiser of the m first burners (110),

characterised in that:

• the network of pipes also connects an outlet of heated stream of heat transfer fluid of the first heat exchanger with an inlet of oxidiser of the m first burners,

• the network of pipes being provided with a system for adjusting and distributing (400) for the adjusting and the distributing of the stream of the first oxidant to the m first burners (110) and for the adjusting and the distributing of the stream of the second oxidant to the m first burners (110).


  9. Equipment according to claim 8 wherein the system for adjusting and distributing comprises a unit for adjusting (400) connected to the second source (30) for the detecting of an available stream or volume of the second oxidant and preferably, also for the adjusting of the streams of the first and of the second oxidants to the m first burners (110) according to the available stream or volume detected.
  10. Equipment according to one of claims 8 or 9, wherein the supply unit also comprises a backup reservoir of second oxidant.
  11. Equipment according to one of claims 8 to 10, wherein m = n.
  12. Equipment according to any one of claims 8 to 11, wherein the network of pipes connects an outlet of heated stream of heat transfer fluid of the first heat exchanger (210) with an inlet of oxidiser of the m first burners (110) without passing through the second heat exchanger (220).
  13. Equipment according to any one of claims 8 to 12, wherein the first source of oxidiser is a pipeline, a reservoir of first liquefied oxidiser or an equipment for separating gases from the air, preferably a pipeline or an equipment for separating gases from the air.
  14. Equipment according to any one of the preceding claims, wherein the supply unit also comprises a backup reservoir of the second oxidant.
  15. Equipment according to any of claims 8 to 14, said equipment comprising a melting furnace with longitudinal burners or with cross-fire burners.