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Hg Valves [Compatibility Mode]

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Presentation by Josef Waltisberg on controlling Hg in cement kilns

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Hg Valves [Compatibility Mode]

  1. 1. The Critical Cycles of Mercury in Cement Kiln System - Installation of Valves Hg Josef Waltisberg Eichhaldenweg 23 CH-5113 Holderbank / Switzerland josef@waltisberg.com Problem and Solution Problem: Kiln with partly high Hg emission Level (average): Direct operation: 30 to 40 [µg/m3N,dry] Compound operation: < 10 [µg/m3N,dry] Peaks: Direct operation: 60 to 100 [µg/m3N,dry] Solution: Reduction of Hg emission in direct operation by installation of “Mercury-Valve” 2 Waltisberg Consulting JW / 04.2010 1
  2. 2. Mercury Measurement Volume Stream to Chimney All the dust from the filter was recycled to the silo Dust Direct Operation Temperature: 155 [° C]: Emission: 36 [µg/m3N,dry] at 10 [%] oxygen µ Dust ~ 8 [%] related to clinker Compound Operation Temperature: 106 [°C]: Emission: < 8 [µg/m3N,dry] at 10 [%] oxygen 3 Waltisberg Consulting JW / 04.2010 Mercury - Balance Ratio Direct / Compound: 40 : 60 Exhaust Gas Volume: 2 [m3N,dry/kg Cli] Concentration Mass Flow Raw Material 0.01 [ppm] 0.019 [mg/kg Cli] Fuel 0.155 [ppm] 0.016 [mg/kg Cli] Kiln without Valve Emission • Direct 36.4 [µg/m3] µ 0.029 [mg/kg Cli] • Compound 4.6 [µg/m3] *) 0.005 [mg/kg Cli] *) Measurement < 8 [µg/m3] ; for simulation: 4.6 [µg/m3] Reduction possibility: During direct operation the dust is discarded from the kiln system INSTALLATION OF A VALVE ! ! ! 4 Waltisberg Consulting JW / 04.2010 2
  3. 3. Mercury Valve Output Gas Volume from Preheater Stream Gas + Dust 4 to Chimney Input to Preheater 2 1: Conditioning Tower 1 2: Homogenizing Silo 3: Raw Mill 4: Filter System 3 Dust and Raw Meal Gas Stream Output(s) of Dust VALVE to Outside Kiln Process e.g. Cement Mill 5 Waltisberg Consulting JW / 04.2010 Mercury Balance Ratio Direct / Compound: 40 : 60 Exhaust Gas Volume: 2 [m3N,dry/kg Cli] Measurements: Direct: 36 [µg/m3] Concentration Mass Flow Compound: Raw Material 0.01 [ppm] 0.019 [mg/kg Cli] < 8 [µg/m3] Fuel 0.155 [ppm] 0.016 [mg/kg Cli] Assumptions: Kiln without Valve Temperature in filter system Emission not changed • Direct 36.4 [µg/m3] µ 0.029 [mg/kg Cli] Same filter • Compound 4.6 [µg/m3] 0.005 [mg/kg Cli] behavior Kiln with Valve -- Dust during direct operation discarded Emission • Direct 16.1 [µg/m3] µ 0.013 [mg/kg Cli] • Compound 2.0 [µg/m3] 0.002 [mg/kg Cli] Valve 0.019 [mg/kg Cli] 6 Waltisberg Consulting JW / 04.2010 3
  4. 4. Mercury - Valve Emission in Function of Discarded Dust [%] of discarded direct operation dust (e.g. to cement mill) 40 35 Emission [ug/m3] 30 25 20 Direct 15 Compound 10 5 0 0 20 40 60 80 100 Valve - Direct [%] 7 Waltisberg Consulting JW / 04.2010 Final Conclusions Reduction of high emission level in direct operation 36 [µg/m3N,dry] 16 [µg/m3N,dry] Hg Peaks in direct operation < 50 [µg/m3N,dry] (limit) Additionally also other cycles cut e.g. thallium, dioxin/furans, etc Problem: In some countries (e.g. USA, Canada) it is not allowed to discard the dust to the cement mill. 8 Waltisberg Consulting JW / 04.2010 4

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