High Pressure Gas Quenching

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High Pressure Gas Quench High Pressure Gas Quenching Advantages of Gas Quenching

Transcript of High Pressure Gas Quenching

  1. 1. High Pressure Gas Quench High Pressure Gas Quenching Advantages of Gas Quenching
  2. 2. High Pressure Gas Quench Reduction of hardening distortion and/or variation of distortion Quenching intensity adjustable by of gas pressure and gas velocity Process flexibility Clean, non-toxic working conditions Integration into manufacturing lines Reproducible quenching result Clean and dry parts, no washing Simple process control Advantages of Gas Quenching
  3. 3. High Pressure Gas Quench High Pressure Gas Quench Quench Media vs. Heat Transfer Coefficient Data taken from: George E. Totten, PhD, FASM Portland State University Department of Mechanical and Materials Engineering Heat Transfer rate, W M-2 K-1
  4. 4. High Pressure Gas Quench 0 100 200 300 400 500 600 700 800 900 0 10 20 30 40 50 60 10 bar N2 10 bar He 20 bar He 40 bar He Fast quenching oil Bellini FS (70C) Hot quenching oil Quench Behavior 3D Loads Oil vs. HPGQ Time Temperature
  5. 5. High Pressure Gas Quench Bubble Boiling Film Boiling Convection t = 10 s 750C 700C 700C 600C 500C 400C 300C 200C Temperature distribution t = 10 s Heat transfer coefficient 5000 10000 15000 20000 l oil Wasser water [W/m K] 2 ref.: Stick, Tensi, HTM 50, 1995 Heat Transfer & Temperature Distribution Immersion Quenching
  6. 6. High Pressure Gas Quench Heat transfer coefficient 1000 2000 3000 4000 [W/m K] 2 Temperature distribution 750C 650C 550C 450C 350C 250C Gas direction Only convection Heat Transfer & Temperature Distribution High Pressure Gas Quenching
  7. 7. High Pressure Gas Quench - Gas (N2, He, H2) - Gas pressure - Gas velocity HPGQ Parameters Quenching Gas
  8. 8. High Pressure Gas Quench Chemical symbol Density at 15 o C and 1 bar Density relative to air Molar mass (kg / kmol) Specific heat capacity Cp (kJ / kg K) Dynamic viscosity (N s / m 2 ) Thermal conductivity (W / m K) Argon Nitrogen Helium Hydrogen Ar 1,6687 1,3797 39,948 0,5024 177x10- 4 22,6x10- 6 N 2 1,170 0,967 28,0 1,041 259x10- 4 17,74x10- 6 He 0,167 0,138 4,0026 5,1931 1500x10- 4 19,68x10- 6 H 2 0,0841 0,0695 2,0158 14,3 1869x10- 4 8,92x10- 6 (at 25o C und 1 bar) Quench Gas Properties
  9. 9. High Pressure Gas Quench 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 16 18 20 N2 He H2 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 16 18 20 Relative Motorpower for cooling gas fans Relative Heat Transfer Coefficient Gas pressure (bar) Gas pressure (bar) N2 He H2 HPGQ Parameters Influencing Factors
  10. 10. High Pressure Gas Quench Helium with Recycling, Consumption per Quench 0.3 m = 10.6 cft Nitrogen without Recycling, Consumption per Quench 55 m = 1942 cft HPGQ Cost Helium vs. Nitrogen
  11. 11. High Pressure Gas Quench - Gas Paths - Gas Fan(s) - Heat Exchanger(s) - Loading - Process flow - Kind of Flow - Gas ( N2, He, H2 ) - Gas pressure - Gas velocity HPGQ Parameters Quenching Chamber
  12. 12. High Pressure Gas Quench HPGQ Parameters Quenching Chamber Multi Chamber Furnace (Cold Chamber) Backfill time to final pressure >> 10 sec Backfill time to final pressure