METHOD TO REDUCE BUILD-UPS, CRUSTS AND RING FORMATION IN CLINKER PRODUCTION

Abstract

Some embodiments are directed to a method to avoid the negative effect of both sulphur and vanadium presence contained in solid fuel used in cement clinker manufacturing line (build-up, kiln rings, etc.). Some embodiments are methods to prepare, dose and use a fuel additive based on an alkaline earth metal to allow the combination of vanadium and sulphur with said added alkaline earth metal, so that corrosion, build-up, crusts and ring formation in cement pre-heaters and kilns due to the presence of those components are avoided.

Claims

1. A method of simultaneously capturing sulphur and vanadium from solid carbonaceous fuels-, wherein the solid carbonaceous fuels contain from 4.5% to 8% in weight of elemental sulphur and from 500 ppm to 5000 ppm of vanadium, the method comprising: preparing a fuel additive composition, the fuel additive composition including, 20%-60% (w/w) of solid active content of an oxide or hydroxide of an alkaline earth metal, 0.5%-5% (w/w) of solid active content of a suspension stabilizer, and 35%-79.5% (w/w) of a water miscible liquid; dosing the fuel additive prepared in the preparing step according to the formula,
Additive Dosage (ml/min)=V.sub.2O.sub.5 (ppm)Fuel Supply (ton/min)A, wherein V.sub.2O.sub.5 (ppm) is the amount of V.sub.2O.sub.5 in ppm that is formed considering that all the elemental vanadium present in the fuel react with oxygen to form V.sub.2O.sub.5, and A is a factor ranging from 1.0 to 4.0; adding the fuel additive to the solid carbonaceous fuel; grinding the fuel additive together with the solid carbonaceous fuel; and feeding the mixture fuel-fuel additive into the preheater and/or kiln, according to the needs of the clinker manufacturing process.

2. The method according to claim 1, wherein the solid active content of the alkaline earth metal used in the preparing step is between 40% and 50% (w/w).

3. The method according to claim 1, wherein the alkaline earth metal is magnesium.

4. The method according to claim 1, wherein the alkaline earth metal is reactive magnesia.

5. The method according to claim 1, wherein the alkaline earth metal has a particle size between 2 and 20 microns.

6. The method according to claim 1, wherein the suspension stabilizer used in the preparing step is selected from the group consisting of Tributyl phosphate (TBP), Triethylamine (TEA), silicone-based surfactants, Cetyl trimethyl ammonium chloride, Cetyl Trimethyl Ammonium Bromine, butoxy polypropylene glycol, Lauryl betaine, Triisobutyl Phosphate (TIBP), Polyethylene glycol (PEG), Sodium dodecyl sulfate, Sodium alpha olefin sulfonate, Sodium Alkane Sulfonate or mixtures thereof.

7. The method according to claim 1, wherein the water soluble liquid is selected from water, methanol, ethanol, propanol, butanol, acetone or mixtures thereof.

8. The method according to claim 1, wherein the fuel additive, after being prepared according to the preparing step is stored for further use.

9. The method according to claim 1, wherein in the adding step, the fuel additive is added to the solid carbonaceous fuel in the solid carbonaceous fuel conveyor belt.

10. The method according to claim 1, wherein in the adding step, the fuel additive is sprayed onto the solid carbonaceous fuel in the belt conveyor.

11. The method according to claim 1, wherein in the adding step, the fuel additive is added to the solid carbonaceous fuel inside the solid carbonaceous fuel mill.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0099] FIG. 1. represents a possible fuel additive dosing system

[0100] FIG. 2. represents sulphur (SO.sub.3) measurements before and after fuel additive is added. Process is running for 75 days without additive. At the 75.sup.th day, fuel additive is added and process was continued with additive for another 105 days.

[0101] FIG. 3. represents pressure in the calciner and in the kiln, as well as the amount of O.sub.2 available in the kiln. Process is running for 75 days without additive. At the 75.sup.th day, fuel additive is added and process was continued with additive for another 105 days.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Example 1

[0102] Clinker production was started using a fuel with the following characteristics:

TABLE-US-00002 Fuel Coke V.sub.2O.sub.5 content 840 ppm Fuel supply into the fuel mill 16 ton/h = 0.267 ton/min

[0103] The clinker production was maintained during 75 days with no additive addition. After 75 days, additive was dosed and added into the fuel.

[0104] Additive dosage was calculated:

Additive Dosage (ml/min)=V.sub.2O.sub.5 (ppm)Fuel Supply (ton/min)A

Factor A=1.1

[0105] Additive Dosage (ml/min)=8400.2671.1=248 ml/min

[0106] Fuel additive was dosed and dispersed on top of the coke that was traveling on the conveyor belt into the fuel mill. Coke and additive were grinded together in the fuel mill. The treated, grounded coke was then fed into the kiln.

[0107] FIGS. 2-3 show the results before and after additive was added.

[0108] From FIG. 2, one can see that SO.sub.3 in the raw mix has a significant decrease after the additive is added (75th day).

[0109] From FIG. 3, one can see a decrease in both pressures in calciner and smoke chamber, which is the chamber just below the calciner, as well as an increase in the amount of O.sub.2 in the smoke chamber. This is easily justified since vanadium will no longer react with oxygen to produce V.sub.2O.sub.5 and more oxygen will be available.

Example 2

[0110] Clinker was produced for 120 days without any fuel additive was used. Process parameters related to the raw mix, fuel (wherein the fuel used was petcoke), hot meal, kiln and clinker were regularly measured.

[0111] After 120 days, fuel additive was measured based on the amount of petcoke and added to the fuel in the fuel mill. During 120 days, fuel additive was constantly used together with the petcoke. The same process parameters related to raw mix, fuel, hot meal, kiln and clinker were regularly measured.

[0112] The average of the process parameters is summarized in Table 2.

TABLE-US-00003 TABLE 2 Process parameters before and after additive addition Process Variable Before After Kiln Clinker prod. (tpd) 1202 1287 Kiln Cleaning (h) 8 2 Kiln O.sub.2 Level (%) 3.8 5.0 Kiln SO.sub.3 Evaporation (%) 53 43 Kiln Energy consumption (kcal/kg clk) 996 929 Kiln Control Temperature ( C.) 811 811 Kiln Calciner pressure (mbar) 38 26 Raw Mix Lime Saturation Factor 103 103 Raw Mix Silica Ratio 2.86 2.81 Raw Mix SO.sub.3 (%) 1.0 1.0 Hot meal SO.sub.3 (%) 5.6 4.4 Hot meal Vanadium (V, ppm) 1008 392 Clinker Lime Saturation Factor 98 98 Clinker Silica Ratio 2.85 2.8 Clinker SO.sub.3 (%) 3.1 3.1 Clinker Free lime (%) 1.1 1.2 Petcoke Sulfur (% S) 5.8 5.8 Petcoke Vanadium (ppm, V.sub.2O.sub.5) 1450 1450 Petcoke Input (ton/min) 0.27 0.27 Additive Dosage (ml/min) 0 528

[0113] Before additive addition, the average daily clinker production was 1202 tons/day. After the additive was used, clinker produced increased to 1287 tons/day.

[0114] During 120 days, 8 hours were dedicated to cleaning before additive was used; with the additive, cleaning was reduced to approximately 2 hours. No build-ups nor ring formation were observed and cleaning was merely for maintenance.

[0115] The level of O.sub.2 in the kiln improved from 3.8% (without additive) to 5.0% (with additive), which also improved burnability.

[0116] SO.sub.3 evaporation was reduced from 53% (without additive) to 43% (with additive), since SO.sub.3 was entrapped by the additive.

[0117] While the process temperature was maintained (811 C.), energy consumption was reduced from 996 kcal/kg (without additive) to 929 kcal/kg (with additive) due to the improved process efficiency.

[0118] The calciner pressure was reduced from 38 mbar (without the additive) to 26 mbar (with the additive), since no build-ups nor ring formations were observed. The additive didn't influence the raw mix properties.

[0119] It was observed that the additive also brought a beneficial impact in the vanadium present in the hot meal, which was reduced from 1008 ppm (without additive) to 392 ppm (with additive). Since the hot meal is heated up in the pre-heater with the hot gases that derive from the kiln, which in turn is heated up by the fuel burned, normally less vanadium will be present in said hot gases and therefore, less vanadium will appear in the hot meal analysis. The clinker properties were not affected by the additive usage.

[0120] Both SO.sub.3 and vanadium levels are reduced with the additive usage.

Example 3

[0121] In another plant, the same process monitoring was done as in Example 2. Clinker was produced for 120 days without any fuel additive was used. Process parameters related to the raw mix, fuel (wherein the fuel used was petcoke), hot meal, kiln and clinker were regularly measured.

[0122] After 120 days, fuel additive was measured based on the amount of petcoke and added to the fuel in the fuel mill. During 120 days, fuel additive was constantly used together with the petcoke. The same process parameters related to raw mix, fuel, hot meal, kiln and clinker were regularly measured.

[0123] The average of the process parameters is summarized in Table 3.

TABLE-US-00004 TABLE 3 Process parameters before and after additive addition. Process Parameter Before After Kiln Clinker prod. (tpd) 2717 2915 Kiln Cleaning (h) 8 3 Kiln O.sub.2 Level (%) 5.4 6.8 Kiln SO.sub.3 Evaporation (%) 42 30 Kiln Energy consumption (kcal/kg clk) 999 950 Kiln Control Temperature ( C.) 916 890 Kiln Calciner pressure (mbar) 49 44 Raw Mix Lime Saturation Factor 103 103 Raw Mix Silica Ratio 2.8 2.8 Raw Mix SO.sub.3 (%) 1.0 1.0 Hot meal SO.sub.3 (%) 5.8 4.6 Hot meal Vanadium(V, ppm) 560 168 Clinker Lime Saturation Factor 98 98 Clinker Silica Ratio 2.9 2.9 Clinker SO.sub.3 (%) 3.3 3.3 Clinker Free lime (%) 1.2 1.2 Petcoke Sulfur (% S) 6.5 6.5 Petcoke Vanadium (ppm V.sub.2O.sub.5) 950 950 Petcoke Input (ton/min) 0.3 0.3 Admixture Dosage (ml/min) 0 428

[0124] Before additive addition, the average daily clinker production was 2717 tons/day. After the additive was used, clinker produced increased to 2915 tons/day.

[0125] During 120 days, 8 hours were dedicated to cleaning before additive was used; with the additive, cleaning was reduced to approximately 3 hours. No build-ups nor ring formation were observed and cleaning was merely for maintenance.

[0126] The level of O.sub.2 in the kiln improved from 5.4% (without additive) to 6.8% (with additive), which also improved burnability.

[0127] SO.sub.3 evaporation was reduced from 42% (without additive) to 30% (with additive), since SO.sub.3 was entrapped by the additive.

[0128] The process temperature was also reduced from 916 C. (without additive) to 890 C. (with additive), energy consumption was reduced from 999 kcal/kg (without additive) to 950 kcal/kg (with additive) due to the improved process efficiency.

[0129] The calciner pressure was reduced from 49 mbar (without the additive) to 44 mbar (with the additive), since no build-ups nor ring formations were observed. The additive didn't influence the raw mix properties.

[0130] It was observed that the additive also brought a beneficial impact in the vanadium present in the hot meal, which was reduced from 560 ppm (without additive) to 168 ppm (with additive). Since the hot meal is heated up in the pre-heater with the hot gases that derive from the kiln, which in turn is heated up by the fuel burned, normally less vanadium will be present in said hot gases and therefore, less vanadium will appear in the hot meal analysis.

[0131] The clinker properties were not affected by the additive usage.

[0132] Both SO.sub.3 and vanadium levels are reduced with the additive usage.

Example 4

[0133] In another plant, the same process monitoring was done as in Examples 2 and 3. This time, a petcoke with a lower content of vanadium was used to see the efficiency of the additive at lower levels.

[0134] Clinker was produced for 120 days without any fuel additive was used. Process parameters related to the raw mix, fuel (wherein the fuel used was petcoke), hot meal, kiln and clinker were regularly measured.

[0135] After 120 days, fuel additive was measured based on the amount of petcoke and added to the fuel in the fuel mill. During 120 days, fuel additive was constantly used together with the petcoke. The same process parameters related to raw mix, fuel, hot meal, kiln and clinker were regularly measured.

[0136] The average of the process parameters is summarized in Table 4.

TABLE-US-00005 TABLE 4 Process parameters before and after additive addition. Process Parameter Before After Kiln Clinker prod. (tpd) 2395 2521 Kiln Cleaning (h) 6 2 Kiln O.sub.2 Level (%) 5.6 7.0 Kiln SO.sub.3 Evaporation (%) 27 15 Kiln Energy consumption (kcal/kg clk) 914 900 Kiln Control Temperature ( C.) 926 917 Kiln Calciner pressure (mbar) 78 72 Raw Mix Lime Saturation Factor 104 104 Raw Mix Silica Ratio 2.85 2.85 Raw Mix SO.sub.3 (%) 1.1 1.1 Hot meal SO.sub.3 (%) 4.2 3.3 Hot meal Vanadium (ppm) 280 56 Clinker Lime Saturation Factor 99 99 Clinker Silica Ratio 2.74 2.7 Clinker SO.sub.3 (%) 3.0 2.9 Clinker Free lime (%) 1.57 1.56 Petcoke Sulfur (% S) 4.7 4.7 Petcoke Vanadium (ppm V.sub.2O.sub.5) 550 550 Petcoke Input (ton/min) 0.3 0.3 Admixture Dosage (ml/min) 0 198

[0137] Before additive addition, the average daily clinker production was 2395 tons/day. After the additive was used, clinker produced increased to 2521 tons/day.

[0138] During 120 days, 6 hours were dedicated to cleaning before additive was used; with the additive, cleaning was reduced to approximately 2 hours. No build-ups nor ring formation were observed and cleaning was merely for maintenance.

[0139] The level of O.sub.2 in the kiln improved from 5.6% (without additive) to 7.0% (with additive), which also improved burnability.

[0140] SO.sub.3 evaporation was reduced from 27% (without additive) to 15% (with additive), since SO.sub.3 was entrapped by the additive.

[0141] The process temperature was also reduced from 926 C. (without additive) to 917 C. (with additive), energy consumption was reduced from 914 kcal/kg (without additive) to 900 kcal/kg (with additive) due to the improved process efficiency.

[0142] The calciner pressure was reduced from 78 mbar (without the additive) to 72 mbar (with the additive), since no build-ups nor ring formations were observed. The additive didn't influence the raw mix properties.

[0143] It was observed that the additive also brought a beneficial impact in the vanadium present in the hot meal, which was reduced from 280 ppm (without additive) to 56 ppm (with additive). Since the hot meal is heated up in the pre-heater with the hot gases that derive from the kiln, which in turn is heated up by the fuel burned, normally less vanadium will be present in said hot gases and therefore, less vanadium will appear in the hot meal analysis.

[0144] The clinker properties were not affected by the additive usage.

[0145] Both SO.sub.3 and vanadium levels are reduced with the additive usage, which is also effective at the lower limit of vanadium content.