ADVANCED COMBUSTION TECHNOLOGIES FOR REGENERATIVE RADIANT TUBE FURNACES November 11,2005 KEMCO-NEDO Seminar on Advanced Industrial furnace Seoul,Korea Jun Sudo Nippon Furnace Kogyo Kaisha, Ltd 2-1-53, 53,Shitte,Tsurumi-ku,, Yokohama,230-8666, Japan
Content 1. General 2. Basic data for HRS-RT RT 3. Combustion Control for HRS-RT RT 4. Industrial application of HRS-RT RT 5. Conclusion
General for Regenerative radiant tube combustion and HRS (High cycle Regenerative combustion System)-RT
Regenerative Burner Classification Burner Type 1. DIRECT FIRED TYPE Twin Type Burner Single Type Burner Applied Furnaces Heating Furnace Heat Treatment Furnace Ladle Preheater Process Heater Crucible Furnace 2. INDIRECT FIRED TYPE Radiant Tube Burner Heat Treatment Furnace
Radiant Tube 1900 53% Total 3,570 pairs by 2001 Direct Fired 1670 Pairs 47% Total Regenerative Burners Installed in Japan by 2001
Conventional Radiant Tube Burner System Regenerative Radiant Tube Burner System FUFL Burner AIR 1000 FUFL Burner REGENERATOR(HONEYCOMB) AIR 350 RECUPERATOR AIR 20 FLUE GAS 280 AIR 20 1100 FUFL 1100 FLUE GAS 600 One-Way Combustion Burner REGENERATOR(HONEYCOMB) Alternative Combustion Comparison of Conventional Recuperative and Regenerative Radiant Tube Burner System
Advantage of HRS RT (High-cycle Regenerative Combustion System RT) HRS-RT Ultimate Heat Recovery Ceramic Honeycomb High Temperature Air Combustion Inside Forced E. G. R. Alternative Switching Combustion Flue Gas Outlet Temp Decrease Uniform Temperature Profile on RT High Fuel Saving Rate Low NOx High Product Quality Longer RT Lifetime Lower Grade RT Material Increase of Productivity
Nox vs Preheated Air Temp. Conv. RT HRS-RT Air Temperature ( )
HRS-RT RT Burner NOx Vs Exhaust Gas Recirculation Tf=1000 Fuel:LNG
Physical Characteristics of Ceramic Honeycomb Material Unit Cordierite Alumina Component Al 2 O 3 35 wt % SiO 2 50 Al 2 O 3 > 98 MgO 13.5 Melting Point 1,450 1,800 Max. Survice Temp. 1,200 1,500 Thermal Expansion Coefficient 10-6 / 1.5 9.0 Compressive Strength A axis 10 10 MPa B axis 1 1 Cell Number Cell/in 2 100, 30 100, 4, 40
Comparison of ceramic honeycomb and ball
1,120 64.2 Nm 3 /hr FLUE GAS COMBUSTION AIR 1,027 59.1 Nm 3 /hr Heat Exchange Rate 167 kcal/30 sec = 20,000 kcal/hr φ100 400L( mm ) Flue Gas Heat Recovery Rate = 75% 280 50 FLUE GAS COMBUSTION AIR Example of Ceramic Honeycomb Performance
Qin=50,000kcal/hr Qin=50,000kcatf=930C m=1.2 Lt=4,000mm Qout=42,923kcal/hr Qout=42,923kcal/hr tf=930c Qao=23,274kcal/hr tao=1,040c ts=1,003c Qexh=7,077kcal/hr tgo=286c Qout 42,923 ηtube = = = 85.8% Qin 50,000 Tube Efficiency for Radiant Tube
Basic data for HRS-RT RT Comparison Test for HRS-RT and Recuperative-RT at KTH(Sweden Royal Institute of Technology)
2005/10/21
SSAB point Elbow - 1 3s 3s 3s 3s 2s Top burner or Recuperative burner 41 Elbow - 2 40 39 38 37 36 35 34 33 32 31 4s 30 3s 29 21 3s 22 20 23 19 24 18 25 17 26 16 27 15 28 14 4s Bottom burner 1 2 3 4 5 6 7 8 9 10 11 12 3s 13 4s 4s 4s 4s 2s Elbow - 3 Temperature measurement points located on the wall of the radiant tube
SSAB recuperative burner NFK regenerative burner Difference 90 85.1 83.3 84.0 82.8 80 71.6 70 65.8 62.9 60 58.6 Efficiency η [%] 50 40 V F,SP = 3 Nm3/h x O2 = 3 % V F,SP = 5 Nm3/h x O2 = 3 % V F,SP = 5 Nm3/h x O2 = 3 % V F,SP = 6 Nm3/h x O2 = 3 % 30 20 13.4 17.5 21.1 24.2 10 0 840 880 950 1000 Set Point Temperature T SSAB,SP [ o C] Comparison of Efficiency between HRS-RT burner and Conventional burner
1000 950 Temperature T [ o C] 900 850 800 750 T09 (O2=6,V=5,T=950) T10 (O2=3,V=5,T=950) T25 (O2=3,V=5,T=950) T26 (O2=6,V=5,T=950) 700 0 1000 2000 3000 4000 5000 6000 7000 x [mm] Temperature profile at 2005/10/21 flow rate of fuel gas 5 Nm 3 /h
Comparison Test for HRS-RT and Recuperative-RT at KTH(Sweden Royal Institute of Technology) Results: Tube Efficiency: HRS - RT : 82.8 % (24.2% higher) Recu.- RT : 58.6 % Longitudinal Tube Temperature Profile: HRS- RT ΔT(Av.) : 75 (70 lower) Recu.- RT ΔT(Av.) : 145 Heat Flux (radiative ( radiative): HRS- RT/ Recu.- RT 2 / 1 (at Tf.av.=626 ) NOx : Almost same level for HRS- RT as for Recu.- RT
Combustion Control for HRS-RT
(1) 100% Load Combustion A Burner B Burner 100% 100% 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec (2) Flow Control(50% Load) A Burner B Burner 50% 50% 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec 30sec (3) Time Interval Control(50% Load) A Burner B Burner 100% 100% 15sec 15sec 15sec 15sec 15sec 15sec 15sec 15sec 15sec 15sec HRS Regenerative Burner Temperature Control
Structure of 4 Way Switching Valve
4 Way Switching Valve
Industrial application of HRS-RT 1. 140 t/h Continuous Galvanizing and Annealing Line Furnace 2. 1.67 t/h Roller Hearth Type Annealing Furnace 3. Small Batch Type Gas Carburizing Furnace
Furnace Temperature( ) 500 600 700 800 RADIANT TUBE FURNACES Catalyst Heating F'ce 触媒加熱炉 Aluminum Heat Treating F'ce アルミ熱処理炉 900 1000 1100 1200 1300 1400 1500 Brazing F'ce ロー付炉 Continuous Atmosphere Heat Treating F'ce 連続雰囲気熱処理炉 Continuous Anealing F'ce 連続焼鈍炉 Batch Type Carburizing F'ce バッチ型浸炭炉 Continuous Carburizing F'ce 連続型浸炭炉 Continuous Normarizing F'ce 連続調室炉 Bright Heat Treating F'ce 光輝熱処理炉 High temp. Air Intensifier 高温空気発生装置 Test F'ces 各種試験炉 Ceramics Heat Treatment F'ce 窯業用熱処理炉 Vacuum Heat Treating F'ce 真空炉 Batch Type Anealing F'ce バッチ式焼鈍炉 Continuous Galvaniging F'ce 連続式亜鉛メッキ炉 Continuous Sintering F'ce 連続焼結炉 Nitriding F'ce 窒化炉 Baking F'ce 焼成炉 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Furnace Temperature( ) Furnace Temperature Range for HRS-RT
Total RT Number.1734 (1734 Pair of HRS-RT Burner) STEEL PRODUCT HEAT TREATMENT 300 250 Number of Radiant Tube 200 150 100 50 0 6 1 88 14 52 172 180 93 85 197 149 141 136 106 78 76 85 59 12 4 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 HRS-RT Burner Installation Record
FUEL KIND LNG LPG COG TOTAL RT TUBE Q'TY 1059 577 98 1,734 COG 6% LPG 33% LNG 61% Fuel Kinds on HRS -RT Installation
TUBE SIZE Q'TY 3" 4" 5" 6" 7" 8" 184 89 318 520 576 56 1,743 8" 3" 8" Total Tubes 56 184 4" 89 7" 576 HRS-RT SALES DATA TOTAL=1,734 Tubes 2005.September 318 5" 520 6" Tube Size on HRS-RT Installation
Strip 2nd Heating Zone Specification Capacity : 140 ton/hr Furnace Temp. : 950 Material Output Temp : 750 Material : Normal Carbon Steel Coil Fuel : LPG Burner : HRS-RT (Honeycomb), 140 kw Strip 1st Heating Zone 2nd Heating Zone (52 pair of HRS-RT) 88m 140 ton/hr Continuous Galvanizing and Annealing Line Furnace Equipped With 52 Pairs of HRS-RT Burners.
Continuous Galvanizing and Annealing Line Furnace Equipped with 52 Pair of HRS-RT RT
Two Pairs of HRS-RT RT Burners Installed on Continuous Galvanizing and Annealing Line Furnace
Capacity :1.67 tons/hr Heating material :Joints Furnace temperature :940 (Max.) Fuel :Natural Gas RT :6 inch, U type Draft :Pull Firing rate per burner :81 kw Cooling Zone Conventional RT Burner Heating Zone, Soaking Zone Regenerative RT Burner 24pairs Material out in Materi 39 m Width : 2.2 m Application Example of Regenerative RT Burner for : Roller Heath Type Annealing Furnace
Roller Hearth Type Annealing Furnace
Calculation Condition : Operating Hours 7,200 hrs/year(24 hr 300 days) Capacity 660,000 kg/year(550 kg/ch 1200 ch/year) Electric Price 15 \/kwh Natural Gas Price 45 \/10,000kcal Room Temperature 20 Furnace Temperature 930 4,500,000 4,000,000 3,500,000 Difference Per Year \2,773,659 \3,931,054 3,000,000 2,500,000 2,000,000 1,500,000 1,000,000 500,000 \1,157,395 \1,490,584 Yen/Year 0 HRS-RT S/E-RT ELECRIC HEATER Comparison of Running Cost in Batch Type Gas Carburizing Furnace
Conclusion Compact and low NOx regenerative radiant tube burner with ceramic honeycomb(hrs-rt) was developed and applied to various heat treatment furnaces in the past decade. Total number of HRS-RT installed so far is 1734 pairs in 230 heat treatment furnaces which is estimated to about 70 % of total regenerative heat treatment furnaces in Japan. As the performance of HRS-RT as averaged data of 37 applications in NEDO FIELD TEST PROJECT(1998-2000), fuel saving rate is 51.0 % (exhaust gas heat recovery rate : 74.3 %) and Nox is 95ppm (11%O2 corr.) Total number of regenerative furnaces(including direct and indirect firing)in Japan is about 600 now whereras total number of industrial furnaces are about 30,000 which takes about 15 % of total CO2 exhaust in Japan. Therefore further aggressive application of regenerative type high performance industrial furnaces should be urged from environmetal view point.