{"id":9176,"date":"2020-03-11T13:24:25","date_gmt":"2020-03-11T13:24:25","guid":{"rendered":"https:\/\/phiheating.com\/knowledge-center\/si-sic-radiant-tubes\/"},"modified":"2022-01-07T10:29:39","modified_gmt":"2022-01-07T03:29:39","slug":"si-sic-radiant-tubes","status":"publish","type":"knowledge-center","link":"https:\/\/phiheating.com\/ja\/knowledge-center\/si-sic-radiant-tubes\/","title":{"rendered":"Si-SiC Radiant Tubes"},"content":{"rendered":"\n

\u201c Faster, Cheaper, Better \u201d<\/strong><\/h2>\n\n\n\n
<\/div>\n\n\n\n

What is a Si-SiC Composite?<\/h3>\n\n\n\n

50% Si + 50% SiC by volume, metallurgical grade Silicon metal with 80 mesh SiC particles<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

Rationale for  Si-SiC Radiant Tubes<\/h4>\n\n\n\n
  • Conventional = Very Long Life<\/li>
  • Enabling = Very High Temp<\/li>
  • Productivity = Higher Throughput<\/li><\/ul>\n\n\n\n

    Conventional Savings<\/h4>\n\n\n\n
    • Excellent creep properties to 1343\u00b0C (2450\u00b0F) = No tube droop or distortion<\/li>
    • Excellent resistance to carburization = No tube corrosion or embrittlement<\/li>
    • Excellent thermal shock & low CTE = No fracture in heat-up or cool-down<\/li><\/ul>\n\n\n\n

      18+ Years Continuous Carburizing Service<\/strong><\/p><\/blockquote>\n\n\n\n

      Compare Alloys to Si-SiC at 1343\u00b0C (<\/strong>2450\u00b0F) = ~8.5 KPSI Stress at <0.6% Strain<\/strong><\/h4>\n\n\n\n
      \"\"<\/figure><\/div>\n\n\n\n

      Si-SiC Composite vs. 600 Alloy (after just 1 hour)<\/h4>\n\n\n\n

      No deformation for the INEX tube tested 360 hours at 1343\u00b0C (2450\u00b0F).<\/p>\n\n\n\n

      \"\"<\/figure><\/div>\n\n\n\n

      Metal Alloy Tubes after < 24 Months<\/strong><\/h4>\n\n\n\n
      \"\"<\/figure><\/div>\n\n\n\n

      Si-SiC Enables Processing > 982\u00b0C (1800\u00b0F)<\/h4>\n\n\n\n
      • Stainless Steel Aging<\/li>
      • Powdered Metal Sintering<\/li>
      • Minerals Processing<\/li><\/ul>\n\n\n\n

        What Limits Furnace Throughput ?<\/h4>\n\n\n\n
        • Metallurgical objectives<\/li>
        • Mechanical constraints<\/li>
        • Radiant tube heat flux<\/li>
        • NOT refractory or burners<\/li><\/ul>\n\n\n\n

          What is Heat Flux ?<\/h4>\n\n\n\n

          Heat flux or thermal flux is the rate of heat energy transfer through a given surface,
          per unit surface.
          (BTU\/hour)\/inch2<\/sup>
          kW\/meter2 <\/sup>   =   2.2 BTU\/hr\/in2<\/sup><\/p>\n\n\n\n

          Design Criteria for Radiant Tubes<\/h4>\n\n\n\n

          Metal Alloy Tubes at 982\u00b0C (1800\u00b0F) :<\/p>\n\n\n\n

          • Conservative = 50 BTU\/hr\/in2<\/sup><\/li>
          • Nominal = 55 BTU\/hr\/in2<\/sup><\/li>
          • Aggressive = 60 BTU\/hr\/in2<\/sup><\/li><\/ul>\n\n\n\n

            Max Service temperature depends on Alloy & Atmosphere<\/p>\n\n\n\n

            Si-SiC Composite Tubes @ 982\u00b0C (1800\u00b0F) :<\/h4>\n\n\n\n

            Nominal = 110 BTU\/hr\/in2<\/sup>
            Maximum Service Temp is 1343\u00b0C (2450\u00b0F)<\/p>\n\n\n\n

            \"\"
            SANKEY DIAGRAM Typical Pusher Furnace<\/strong><\/figcaption><\/figure><\/div>\n\n\n\n

            Parasitic or Standing Losses average ~20%<\/p>\n\n\n\n

            • Wall Losses<\/li>
            • Opening Losses<\/li>
            • Cooling & Conveyor Losses<\/li>
            • Fixtures, Trays, Baskets<\/li>
            • Storage Losses (Batch Furnace)<\/li><\/ul>\n\n\n\n

              FASTER Cycle Time<\/h4>\n\n\n\n
              • Increases furnace throughput<\/li>
              • Reduces per unit standing (parasitic) losses<\/li>
              • Does NOT reduce process energy required<\/li>
              • Does NOT improve combustion  efficiency<\/li><\/ul>\n\n\n\n
                \"\"<\/figure><\/div>\n\n\n\n

                Compare Alloys to Si-SiC at <\/strong>1343\u00b0C (2450\u00b0F) = ~8.5 KPSI Stress @ <0.6% Strain<\/strong><\/h3>\n\n\n\n
                \"\"<\/figure><\/div>\n\n\n\n

                CHEAPER Furnace Operation<\/h4>\n\n\n\n
                • 25% Increase in Throughput  = 25% More Load (Reducing Furnace Operating Hours by 20%)<\/li>
                • Process Energy Required Remains the Same i.e. Work on Load is Unchanged = 0.0<\/li>
                • Standing Energy Losses of 20% Eliminated  for the 20% of Furnace Hours Reduced  = +4.0%<\/li>
                • Offset Somewhat by Higher Exhaust Losses (1906\u00b0F > 1999\u00b0F) Available Heat   =  -2.0%<\/li><\/ul>\n\n\n\n

                  \u201cSAME-WORK\u201d SCENARIO<\/strong><\/p>\n\n\n\n

                  \"\"<\/figure><\/div>\n\n\n\n

                  \u201cBack of the Envelope\u201d Savings<\/strong><\/h4>\n\n\n\n

                  1200 more hours\/year\/furnace
                  5.2 hours\/cycle
                  231 cycles\/year
                  2,000 lbs\/cycle
                  461,538 lbs\/year
                  $1.10 Sales Value \/ lb
                  $507,692 Increased Sales
                  50% Variable Cost
                  $253,846 EBIT \/ furnace<\/p>\n\n\n\n

                  Compare with:<\/p>\n\n\n\n

                  • New Si-SiC Radiant Tubes <$25,000<\/li>
                  • New EGR-type Burners, if Needed <$25,000<\/li>
                  • Used or New Furnace<\/li><\/ul>\n\n\n\n

                    Why Are Si-SiC Tubes BETTER ?<\/h4>\n\n\n\n
                    • Proven Life >18 Years in Carburizing<\/li>
                    • High Temp Processing to 2300\u00b0F<\/li>
                    • 25% More Product Throughput<\/li>
                    • < 12 Months Payback<\/li><\/ul>\n\n\n\n

                      FASTER, CHEAPER, BETTER @ 1400\u00b0F – 2300\u00b0F<\/strong><\/p><\/blockquote>\n\n\n\n

                      \"\"<\/figure><\/div>\n\n\n\n
                      \"\"<\/figure><\/div>\n\n\n\n

                      <\/p>\n","protected":false},"excerpt":{"rendered":"

                      \u201c Fas […]<\/p>\n","protected":false},"featured_media":4985,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","class_list":["post-9176","knowledge-center","type-knowledge-center","status-publish","has-post-thumbnail","hentry"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t