Steven J. O Connor Anthony J. Fennell

Transcription

1 Steven J. O Connor Anthony J. Fennell

2 TOPICS CONSIDERED Regenerative Furnaces Scale Free Heating Oxygen Sensors

3 REGENERATIVE FURNACES Bao Steel No. 1 Furnace 3 Bao Steel No. 3 Meishan Bao Steel No. 1 Furnace 1 Dual Regenerative Burners for Blast Furnace Gas

4 BAO STEEL 2050 RETROFIT SHANGHAI, CHINA Eight zone walking beam furnace 350 MTPH capacity Hot strip mill Mixed gas ( Kcal/NM3) Bottom heat1 and heat2 zones converted to regenerative

5 FURNACE AS DESIGNED SOAK HEAT 2 HEAT 1 PREHEAT (NOT USED) METERS EFFECTIVE LENGTH

6 FURNACE AS MODIFIED METERS EFFECTIVE LENGTH

7 BAO STEEL 2050 RETROFIT SHANGHAI, CHINA % fuel savings 47ppm NOx at 11% O2 140 C exhaust gas temperature 500 C air preheat temperature

8 BAO STEEL #3 HSM SHANGHAI, CHINA Eight zone walking beam furnace 250 MTPH capacity Hot strip mill Mixed gas ( Kcal/NM3) All zones regenerative except top soak Top soak hot air through recuperator

9 BAO STEEL #3 HSM, SHANGHAI, CHINA 42.5 METERS EFFECTIVE LENGTH

10 MEISHAN STEEL, MEISHAN CHINA Eight zone walking beam furnace 250 MTPH capacity Hot strip mill Mixed gas ( Kcal/NM3) All zones regenerative except top soak Top soak hot air through recuperator

11 MEISHAN STEEL MEISHAN, CHINA 42.5 METERS EFFECTIVE LENGTH

12 MEISHAN STEEL, MEISHAN, CHINA 262 Kcal/Kg fuel rate % scale loss 30-55ppm NOx at 11% O 2 <20 C head to tail differential

13 BAO STEEL 2050, #1 FCE SHANGHAI, CHINA Eight zone walking beam furnace 350 MTPH capacity Hot strip mill Mixed gas ( Kcal/NM3) All zones regenerative except top soak Top soak hot air through recuperator

14 BAO STEEL 2050, #1 FCE SHANGHAI, CHINA 50 METERS EFFECTIVE LENGTH

15 BAO STEEL 2050, #1 FCE SHANGHAI, CHINA 243 Kcal/Kg fuel rate 30-55ppm NOx at 11% O 2 <20 C head to tail differential

16 DUAL REGENERATIVE BURNER The dual regenerative burner makes BFG in a high temperature application possible, reducing customer dependency on higher cost fuel and saving money.

17 Bloom Engineered Burner Burner is custom-designed for application using CFD modeling and laboratory testing Burner is designed with two stage combustion using air staging with air passages through a refractory baffle to control mixing, heat release and emissions 90% pullback is expected using these burners

18 Burner Conceptual Design

19 BLOOM DUAL REGENERATIVE BURNER

20 BLOOM DUAL REGENERATIVE BURNER

21 SCALE FREE HEATING Control of sub-stoichiometric combustion of natural gas to produce a neutral atmosphere within the furnace. Air/fuel ratio to produce a neutral atmosphere may be as low as 5:1. The ratio varies with steel surface temperature. Implementation requires integration of a heat recovery system.

22 Scale Free Process Requirements

23 Scale Formation for Carbon Steel

24 Benefits Reduction of scale formation during heating Significant production and maintenance cost advantages Improvement in product surface quality Reduction of scale disposal costs Environmental considerations Possible Reduction in energy use

25 PROCESS BACKROUND Basic process has been known for 40 plus years A few operating forging installations have been built Current DOE modernization project 3 Active applications

26 CONTINUOUS REHEAT FURNACE Soak zone at 50% air Low Efficiency Air preheated to F or Oxygen boost Stoichiometric Combustion to Steel Surface Temperature of 1700 F Ratio proportional to 50% air in remaining zones Stiochiometric zones more often than not use secondary combustion through air nozzles

27 Scale Free Atmosphere Generation Use of highly preheated air (~ F) for combustion of natural gas. Requires high temperature recuperator, hot air piping and hot air burners. This option is attractive for new installations Use of oxygen or oxygen enriched air for combustion. This requires constant source cost of oxygen supply. This option is more attractive for retrofit applications Use of combination for existing installations with lower degree ((say ~ F to F) of preheat and use of oxygen to boost oxygen in combustion air

28 Active Applications Rotary Steel Reheat Furnace Pusher Billet Reheat Furnace Batch Forging Operation

29 Rotary Steel Reheat Furnace 100,000 TPY Current cold air operation Objectives: Improve fuel economy Minimize scale loss Improve die life Product quality improvement Environmental neutral

30 Pusher Billet Reheat Furnace???? TPY, rebar New, recuperated furnace Objectives: Minimize scale loss Environmental neutral????

31 Batch Forging Operation Ring rolling operation, 20 in dia x 2.1 Tn billets Only last (soak) part of heating cycle is scale free Furnaces to operate connected in pairs One furnace on soak - scale free exhaust to other Other furnace on heat stiochiometric Objectives: Improve fuel economy Minimize scale loss

32 OXYGEN SENSORS Bloom has an agreement with Marathon Sensors to be their representative, integrator and partner for the steel and aluminum industries. We will market the sensors, private labeled under the Enviro-Helper trade name. Our long term objective is to engineer and market leading edge systems based on this technology.

33 Oxygen Analysis Can directly reflect state of combustion Can compensate for changes in fuel characteristics Can compensate for controls aberrations Prevent overly-oxidizing/reducing environment Can reduce NO x and CO formation Key is accurate, real-time measurement

34 Benefits of Measuring O 2 Safety Maintain better fuel/air ratios Maximize fuel savings Reduce Nox and CO

35 Oxygen Analysis What is the ideal oxygen sensor? Simple and inexpensive Little or no maintenance Not affected by mass flow variations Temperature compensated Installed in area of complete combustion without bias from air infiltration Able to withstand high temperatures Accurate measurement from PPM to 21%*

36 Zirconia based Sensors Two categories Extractive ( dry ) sampling In-situ ( wet ) sensors Heated Non-heated

37 Non-Heated In-situ Sensors Wet measurement Located directly in process gas stream Sample flows directly over cell Unheated cell Heat from process utilized Temperature compensated

38 High-Temp Oxygen Sensor

39 High-Temp In-situ Sensors Advantages Wet Measurement Oxygen measurement based on actual process gas temperature True real time measurement Range of 1200 F F No sampling, cooling, filters, heaters, etc. Located in or near the combustion zone Very fast response time to changes Minimal maintenance No calibration required but calibration check available

40 High-Temp In-situ Sensors Disadvantages Thermal shock: long insertion and removal process* Ineffective below 1100 F * New Temperature Resistant Sensor in Beta Test at AK, Middletown

41 High-Temp In-situ Sensors; Considerations Location Zoning of furnaces allows information to be extracted relative to certain zones or even individual burner banks Control vs. Monitoring Control makes O2 a high Return-on-Investment technology Monitoring offers no pay-back Furnace Pressure Low pressure allows high air infiltration during door opening which gives false high reading on O2

42 High-Temp In-situ Sensors; Considerations Reference Air Must be clean and dry. Moisture destroys sensors while dirt shortens life as impurities diffuse into zirconia Sheath Materials Hexalloy (SiC) most rugged but prone to Fe attack if mounted horizontally in line of gas flow Alumina least costly but must be handled carefully* Probe Length Dormant (Coanda) gas along furnace walls requires 6 insertion past hot face for accurate readings Particulates Sacrificial boot needed when particulates could accelerate electrode wear

43 Control Systems Mass Flow Pressure Balance

44 Mass Flow Control Flow transmitter P Controller Oxygen Control Air Gas Flow transmitter P Air valve Gas valve

45 Pressure Balance Control Oxygen Control Air Gas Impulse line Air Valve Motor driven bleed valve Pressure balance ratio regulator

46 Applications Reheat Furnaces AL Melters Forge Furnaces Batch Anneal Furnaces Alternative Fuels Compensation

47 Installations AK Steel, OH Strip Mill Reheat Furnaces MacSteel, Monroe Pusher Billet Furnace Nucor, AK Tunnel Furnace Nucor, UT Pusher Billet Furnace USS Lorain Rotary Pipe Furnace