GLASS MELTING PROCESS WITH VERY LOW TO ZERO-CO2 EMISSION

Abstract

A process for melting vitrifiable materials to produce flat glass, including (i) providing a furnace having at least one melting tank with electrical heating means, a fining tank with oxy-combustion heating means, a neck separating melting tank and fining tank, inlet mean(s) located at the melting tank and outlet mean(s) located downstream of the fining tank; (ii) charging the vitrifiable materials including raw materials and cullet in the melting tank, the amount of cullet being at least 10% in weight of the total amount of vitrifiable materials and the raw materials including less than 25% in weight of carbonate compounds; (iii) melting the vitrifiable materials in the melting tank; (iv) fining melt by heating with the oxy-combustion heating means; (v) flowing the melt from the fining tank to a working zone through the outlet mean(s); and (vi) capturing CO.sub.2 from flue gas having a CO.sub.2 concentration of at least 35%.

Claims

1. A process for melting vitrifiable materials to produce flat glass, comprising: providing a furnace comprising (i) at least one melting tank comprising electrical heating means, (ii) a fining tank provided with oxy-combustion heating means, (iii) at least one neck separating the at least one melting tank and the fining tank, (iv) inlet mean(s) located at the at least one melting tank and (v) outlet mean(s) located downstream of the fining tank; charging the vitrifiable materials comprising raw materials and cullet in the at least one melting tank with the inlet mean(s), the an amount of cullet being at least 10% in weight of the a total amount of vitrifiable materials and the raw materials comprising less than 25% in weight of carbonate compounds; melting the vitrifiable materials in the at least one melting tank by heating with the electrical heating means; fining the melt in the fining tank by heating with the oxy-combustion heating means alimented with gas and/or hydrogen; flowing the melt from the fining tank to a working zone through trough the outlet mean(s); capturing CO.sub.2 from flue gas, said flue gas having a CO.sub.2 concentration of at least 35%; wherein: its an electrical input fraction for melting and fining ranges from 50% to 85%; and the step of capturing CO.sub.2 from flue gas comprises step(s) of compression and/or dehydration.

2. The process for melting vitrifiable materials according to claim 1, wherein the amount of cullet is at least 30% in weight of the total amount of vitrifiable materials.

3. The process for melting vitrifiable materials according to claim 1, wherein the oxy-combustion heating means are alimented with at least 50% hydrogen.

4. The process for melting vitrifiable materials according to claim 1, wherein said flue gas has a CO.sub.2 concentration of at least 40%.

5. The process for melting vitrifiable materials according to claim 4, wherein said flue gas has a CO.sub.2 concentration of at least 50%.

6. The process for melting vitrifiable materials according to claim 1, wherein the capturing CO.sub.2 from flue gas consists essentially of compression and/or dehydration.

7. The process for melting vitrifiable materials according to claim 1, further comprising eliminating acidic components from said flue gas.

8. The process for melting vitrifiable materials according to claim 7, wherein the eliminating acidic components from said flue gas is prior or concurrent to the capturing CO.sub.2.

9. The process for melting vitrifiable materials according to claim 1, further comprising cullet pre-heating, at least partially by recovering heat from the furnace, before charging said cullet in the at least one melting tank.

10. The process for melting vitrifiable materials according to claim 9, wherein a maximum temperature of cullet at the cullet pre-heating is 450 C.

11. The process for melting vitrifiable materials according to claim 1, wherein it comprises further a step of pre-melting at least a part of the cullet in an auxiliary melting tank and flowing the pre-melted cullet to the at least one melting tank.

12. The process for melting vitrifiable materials according to claim 1, wherein the raw materials comprise less than 10% in weight of carbonate compounds.

13. A furnace configured for carrying out the process of claim 1.

14. The process for melting vitrifiable materials according to claim 1, wherein the oxy-combustion heating means are alimented with at least 80% hydrogen.

15. A process for melting vitrifiable materials to produce flat glass, comprising: providing a furnace comprising (i) at least one melting tank comprising an electrical heater, (ii) a fining tank provided with oxy-combustion heating, (iii) at least one neck separating the at least one melting tank and the fining tank, (iv) an inlet located at the at least one melting tank, and (v) an outlet located downstream of the fining tank; charging the vitrifiable materials comprising raw materials and cullet in the at least one melting tank with the inlet, an amount of cullet being at least 10% in weight of a total amount of vitrifiable materials and raw materials comprising less than 25% in weight of carbonate compounds; melting the vitrifiable materials in the at least one melting tank by heating with the electrical heater; fining the melt in the fining tank by heating with the oxy-combustion heating alimented with gas and/or hydrogen: flowing the melt from the fining tank to a working zone through the outlet; and capturing CO.sub.2 from flue gas, said flue gas having a CO.sub.2 concentration of at least 35%; wherein: an electrical input fraction for melting and fining ranges from 50% to 85%; and the capturing CO.sub.2 from flue gas comprises compression and/or dehydration.

Description

EXAMPLES

[0116] The following examples of processes were computed, considering the same glass pull (750 t/day) and same cullet amount (40% in weight) and considering the following furnace designs:

[0117] Example 1 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with air/natural gas (NG) (full combustion energy)

[0118] Example 2 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with O.sub.2/natural gas (NG) (full combustion energy).

[0119] Example 3 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with O.sub.2/H.sub.2 (full combustion energy).

[0120] Example 4 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with air/natural gas (NG) and with electrodes for electro-boosting. Electrical power of electro-boosting was set at 5 MW.

[0121] Example 5 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with O.sub.2/natural gas (NG) and with electrodes for electro-boosting. Electrical power of electro-boosting was set at 5 MW.

[0122] Example 6 (comparative): conventional combustion glass melting furnace with one tank including melting and refining zones, equipped with burners fed with O.sub.2/H.sub.2 and with electrodes for electro-boosting. Electrical power of electro-boosting was set at 5 MW.

[0123] Example 7 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/natural gas (NG) and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 16 MW.

[0124] Example 8 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/H.sub.2 and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 16 MW.

[0125] Example 9 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/natural gas (NG): H.sub.2 50:50 and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 16 MW.

[0126] Example 10 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/natural gas (NG) and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 21 MW.

[0127] Example 11 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/H.sub.2 and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 21 MW.

[0128] Example 12 (invention): segmented furnace equipped with a melting tank comprising electrodes, a fining tank with burners fed with O.sub.2/natural gas (NG): H.sub.2 50:50 and a neck separating the melting and fining tanks. Electrical power in the melting tank was set at 21 MW.

[0129] In comparative Examples 1-6, the used raw materials comprise the following carbonate compounds: Na.sub.2CO.sub.3, dolomite and limestone, corresponding to 37.3% in weight of carbonate compounds in the raw materials.

[0130] In Examples 7-12, according to the invention, the dolomite and limestone were replaced by decarbonated compounds, namely dolime and quick lime, so that the raw materials in those examples comprise 19.3% in weight of carbonate compounds (essentially Na.sub.2CO.sub.3).

[0131] Table 1a shows information related to Energy. Table 1b shows information related to Flue gas and CO.sub.2 capture step.

TABLE-US-00001 TABLE 1a Energy Electrical Electrical Total input Combus- power power fraction Example tible fuel (MW) (MW) (%) 1 comp. air NG 0 47 0 2 comp. O.sub.2 NG 0 44 0 3 comp. O.sub.2 H.sub.2 0 44 0 4 comp. air NG 5 43 0 5 comp. O.sub.2 NG 5 39 12.8 6 comp. O.sub.2 H.sub.2 5 39 12.8 7 inv. O.sub.2 NG 13.4 27.4 48.9 8 inv. O.sub.2 H.sub.2 13.4 27.4 48.9 9 inv. O.sub.2 H.sub.2/NG 50:50 13.4 27.4 48.9 10 inv. O.sub.2 NG 18.4 23.4 78.6 11 inv. O.sub.2 H.sub.2 18.4 23.4 78.6 12 inv. O.sub.2 H.sub.2/NG 50:50 18.4 23.4 78.6

[0132] As to Energy, Table 1a gives the combustible, the fuel, the electrical and total power used in the computations as well as the electrical input fraction (electricity/total energy).

[0133] As to Flue gas, Table 1b gives: [0134] the flue gas that is extracted to undergo the CO.sub.2 capturing step: either the flue gas from the whole furnace (all, extracted from melting and fining tanks) or from the melting tank only (in case of use of 100% H.sub.2 as fuel in segmented furnaces, where no CO.sub.2 are then present in flue gas from fining tank); [0135] the flow rate of the flue gas (wet) that undergoes the CO.sub.2 capturing step; [0136] the CO.sub.2 concentration (defined for the dry flue gas, excluding H.sub.2O); [0137] the H.sub.2O concentration.

TABLE-US-00002 TABLE 1b Flue gas flue gas CO.sub.2 conc. CO.sub.2 capture Flue gas for flow rate (dry, excl. H.sub.2O tons Amine Dehydr./ Example CO.sub.2 capture (Nm.sup.3/h, wet) H.sub.2O) conc. CO.sub.2/y. abs-des compress. 1 comp. all 69742 12.9% 21.0% 119673 x x 2 comp. all 22634 63.1% 53.7% 113650 x 3 comp. all 24005 33.7% 75.8% 33642 x x 4 comp. all 57550 13.4% 20.9% 102397 x x 5 comp. all 19308 59.6% 51.3% 96375 x 6 comp. all 20384 34.1% 71.8% 33642 x x 7 inv. all 10840 39.50% 44.40% 40913 x 8 inv. melting 2920 47.30% 35.00% 15455 x 9 inv. all 11255 31.10% 53.10% 28184 x 10 inv. all 7855 28.50% 36.20% 24547 x x 11 inv. melting 2920 47.30% 35.00% 15455 x 12 inv. all 7936 24.50% 40.20% 20001 x x

[0138] As to CO.sub.2 capture, Table 1b shows the processes where amine absorption-desorption steps and/or dehydration/compression step(s) are required (marked with x).

[0139] Table 1b shows also the total amount of CO.sub.2 (in tons) produced over a year (taking into account the glass pull defined).

[0140] Tables 1a and 1b illustrate very well that the processes of the invention (examples 7-12) show a lot of advantages, compared to classical furnaces (examples 1-6) without the specific design of the invention and without using some decarbonated compounds in the raw materials: [0141] much lower total energy consumption (30 MW); [0142] lower amount of CO.sub.2 produced over a year; [0143] lower volumes (or flow rates) of flue gas to be treated with CO.sub.2 capture, thereby limiting operational costs and/or investments; [0144] higher CO.sub.2 concentration in treated flue gas (esp. 25%, and up to 47%), thereby allowing to avoid an expensive and energy-consuming absorption-desorption step (for ex. with amines) and using essentially simple dehydration/compression step(s); [0145] lower H.sub.2O concentration in flue gas to be treated with CO.sub.2 capture, thereby also limiting operational costs for the dehydration step.

[0146] Concerning the amount of CO.sub.2 produced over a year for the examples according to the invention (examples 7-12), one reaches low values (<40000 tons/year) that allows more easily the captured CO.sub.2 to be valorized locally, thereby limiting its transportation (for use or sequestration at distance) that leads to significant additional costs (for the transport itself if by trucks for example, or for investment in pipeline installations).

[0147] Contrariwise, comparative examples 1-6 show a very low CO.sub.2 concentration in the flue gas (thereby requiring an amine capture), and/or a high total energy consumption (esp. close or higher than 40 MW), and/or high volumes of flue gas to be treated with CO.sub.2 capture, and/or high H.sub.2O concentration (esp. above 50%) in flue gas to be treated with CO.sub.2 capture, and/or high amount of CO.sub.2 produced over a year (esp. close to or higher than 100000 tons).