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What’s happening in your EAF

Performances for a new EAF paradigm control

 

How can

New Process Technology and New Equipment

Improve your Furnace Operation!

Decrease your Production Cost!

 

  

Advanced Modern Physics - Mathematics, Applied to

Electric Arc Furnaces in Steelmaking plants

for Environment saving.

 

 Physics - Mathematical Models and Algorithms,

Analytical and Numerical solutions,

For Advanced Smart EAF

 N.E. ITALY - Ed. A.F. - 2020

 

How can New Process Technology and New Equipment Improve your Furnace Operation and Decrease your Production Cost?

 

·       The headlined question should be of great interest for most of the steel mills producing steel by melting scrap in electric arc furnaces.

·       Operation of arc furnaces have changed in a radical way the recent years and will do so even in the future due to new developed equipment and process technologies.

·       Unit prices of electrical energy, electrodes, fuel, carbon, oxygen, refractory, scrap, lime, etc always change from time to time due to market situations.

·       New operation technology, new equipment for improving of furnace operation and energy savings are developed and are proposed by suppliers.

·       Especial, when the market situation changes with dumped market prices it is important to trim the furnace operation and reduce the conversion costs of steel in the furnace(s).

·       Here follows some important and interesting questions you may have or will have in the future:

 

·       Do you change furnace operation and equipment due to trends in the market?

·       Is a DC arc furnace the correct solution for Your local operation conditions?

·       Is a twin shell furnace an intresting option of a new furnace installation?

·       Is a shaft furnace beneficial from energy recovery, production increase and environmental reasons?

·       Is a change of furnace shell geometry, i.e. increased shell height and decreased shell diameter, beneficial?

·       Is oxy-fuel burners and/or Coherent Jet burners beneficial and when and how shall You use the burners in the most efficient way?

·       Is post combustion with excess oxygen beneficial and when and how shall you use excess oxygen to have an efficient post combustion?

·       Is a new more powerful furnace transformer with series reactor (fixed or controlled reactance) a beneficial investment?

·       Is a SVC system for voltage stabilisation, power factor correction and flicker reduction a beneficial investment?

·       Is “off-line” pre-heating and pre-cleaning of scrap a beneficial investment?

·       How does new equipment impact the performance of existing auxiliary equipment like electrical power supply, power factor correction, media supply (oxygen, fuel, cooling water), furnace hall ventilation and bag house?

·       Are You sure that all these new technologies and new proposed equipment are good and will improve operation, will increase production, will reduce energy consumption and reduce the overall operation costs for your furnace(s)?

 

Today, AI new algorithms programs for simulation of the melting process in arc furnaces are developed to optimise the furnace operation and to see the real impact of new equipment on furnace operation, production and production costs, which together with experiences can tell You in advance, whether proposals from suppliers of new operation technology and equipment real will fulfil the proposed guarantees and operation improvements.

 

WEMES-AF Eng-SEED Forces in Italy has developed such simulation programs with which the complete melting process and furnace operation can be simulated in advance to see the real impact of proposed operation changes and the impact of new equipment on furnace operation, production and production costs.

 

The computer program EAFDyn makes a dynamic simulation of electrical power fluctuations and network disturbances like voltage fluctuations, current fluctuations, flicker, negative sequences current and voltage in AC and DC arc furnaces in different operation modes,like scrap melting and or refining without and with SVC or VSC systems.

 

The computer program Scrap makes a dynamic simulation of the heat transfer between scrap and off-gases from burners or from furnace with regards to time dependent gas flows, gas temperature, gas composition and gas pressure for preheating of scrap in a shaft, in a bucket or in a tunnel.

The computer program EAFMelt makes a dynamic simulation of the melting process in a AC as well as in a DC single shell as well as twin shell arc furnace, with which the following can be simulated versus operation time.

 

·       Impact of preheating of scrap with burners in waiting shell in a twin shell furnace concept.

·       Impact of furnace shell geometry.

·       Impact of process variables like scrap composition, electrical melt down program, burner operation program, oxygen-carbon lance program, etc.

·       Impact of preheated and precleaned scrap from organic pollutants outside furnace shell in a shaft, in a tunnel or in a separate preheating process.

·       Impact of post combustion with oxygen excess.

·       Impact of time controlled furnace pressure.

·       Impact of tight furnace, i.e. operation of slag door, cleaning of roof ring, etc.

·       Impact of refractory insulation on water-cooled surfaces.

·       Impact of fixed or controlled series reactor on production, specific consumption and network disturbances (flicker)

·       Impact of a SVC or a VSC system on voltage stabilisation, flicker and resultant power factor correction.

·       Impact of fault levels on voltage stabilisation, flicker and production

·       Impact of furnace operation schedule in a multi furnace plant.

 

The computer program EAFMelt has been used during ten years to optimise furnace operation and to check the impact of new proposed equipment and operation methods in arc furnaces on more than 30 furnaces in Europe and North America. Comparison of operation results and simulated results show accuracy better then 3 %.

 

 

The computer program LMFHeat makes a dynamic simulation of the heating process in AC as well as in DC ladle furnaces with which the following can be simulated versus operation time.

 

·       Complete process in AC ladle furnaces from tapping of steel from primary furnace to casting of steel.

·       Complete process in DC ladle furnaces from tapping of steel from primary furnace to casting of steel.

·       Impact of process variables

·       Impact of preheated ladles

·       Impact of oxy-fuel burners in roof

·       Impact of furnace pressure

·       Impact of tight furnace

·       Impact of refractory insulation on water-cooled surfaces

·       Impact of series reactor

·       Impact of time controlled parallel load (simultaneous melting in parallel connected furnaces) on production (heating speed) and specific consumption, resultant electrical load

·       Impact of voltage stabilisation by means of SVC system

·       Impact of fault levels on voltage stabilisation and production

 

The computer program EAFOffgas makes a dynamic simulation of the off-gas system. The EAFOffgas calculates the in-leakage of false air, post combustion of not burnt CO in the duct, heat losses in water-cooled and self-cooled duct, fuel consumption in a post combustion chamber for decomposition and post combustion of organic pollutants in the off-gases, energy recovery in a gas cooler, water consumption in a quenching chamber for fast cooling of the off-gas and the need of dilution air in the bag house to cool the off-gases at either constant flow or constant temperature control of the gas from the bag house to the stack.

 

The following cases can be simulated by means of the program EAFOffgas

 ·       Impact of water-cooled and self-cooled ducts.

·       Impact of coarse dust/pre combustion chamber.

o   Impact of post combustion (PCC) system for decomposition and post combustion of off-gases.

o   Impact of fast cooling of the off-gas in a gas cooler using air or water as cooling medium.

·       Impact of fast cooling of the off-gas in a quenching system.

·       In-leakage of “false” air in gap between furnace and duct system.

·       Heat losses in water-cooled ducts.

·       Heat losses in self cooled ducts.

·       Duct wall temperature in self-cooled ducts.

o   Fuel consumption of burner(s) for decomposing and post combustion of off-gases.

·       Water consumption in quenching system for cooling of the off-gases.

·       Additional water vapour in the off-gases after quenching.

o   Gas velocity and pressure drop in ducts, combustion chambers, coolers, bag house and fan power.

o   Off-gas flow, temperature and composition with different control philosophy of Bag House.

 

The computer program ProdCost makes a spreadsheet calculation and diagrams of production, production costs and investment-benefit analysis of the impact of changed operation practice and new investments on production, production costs and benefit and return of new investments.

 

 Furnace Operation Check Up

 WEMES-AF Eng has competence and experiences to optimise your arc furnace installation from the electrical power supply to the off-gas stack

 The above figures illustrates the scope of an optimisation work of your arc furnace by simulations of impacts of proposed furnace operation from the high voltage electrical power supply of the steel plant with regards to electrical power consumption, power factor correction and net work disturbances like power fluctuation, voltage fluctuation (flicker), current fluctuation, negative sequence voltage and current components and harmonics to the off-gas cleaning system with regards to off-gas flow and off-gas temperature distribution in water cooled ducts, self-cooled ducts, canopy, bag house and stack and emission of organic pollutants, mercury and carbon dioxide (CO2).

 

WEMES-AF Eng offers you a complete check up of the operation of the furnace(s) in your melt-shop and an optimisation of the operation of the furnace(s) and a study of the impact of proposed new equipment on production, specific consumptions and production costs and the beneficial of investment in new equipment.

 

A furnace operation check up followed by an optimisation of furnace operation comprises:

         -             Check up of actual furnace operation and data collection.

-             Short circuit test (Dip test), if the furnace short circuit impedance is unknown.

-             Computer simulations of the melting process partly with actual operation parameters and new optimised operation parameters.

-             Proposals to change operation parameters and melting programs for electrical energy, burners, oxygen lance, post combustion, etc.

-             Computer calculation of electrical operation parameters and load curves for proposed secondary voltages on furnace transformer.

-             Impact of new operation equipment and operation parameters in the furnace on existing auxiliary equipment.

-             Impact of new operation equipment on production, production costs and benefits analysis on new operation equipment.

-             Documentation and reports.

 

 A normal time for a check up as listed above is a 4 to 5 days visit on site for furnace operation check up and data collection followed by a 7 to 10 days home work for simulations, documentation and reports.

  

The costs for a furnace check up followed by an optimisation of the furnace operation are much less than the potential savings of money coming out from an optimised operation of your furnace(s).

  

If the offer is of interest for you, please contact WEMES-AF Eng for a more detailed offer and terms for a check up of your furnace(s) or for a study of the impact of new proposed equipment and operation technology.

 

More information about WEMES with references can be found on our Web site www.wemes.it

 

 Summary EAF (Electric Arc Furnaces), LRF, SAF

 Electrical energy consumption decrease, 100 to 110 kWh/ton

Potential production rate increase, 20 to 25 %

Electrode consumption decrease, 0.3 to 0.5 kg/ton

Complete dry scrap, eliminates explosion at charging

Reduced network disturbances (flicker), 25 to 30 %

Dust generation decrease, 25 to 30 %

 

Summary for BOF (Basic Oxygen Furnaces)

 

Potential production rate increase, 4 to 5 %

Complete dry scrap, eliminates explosion at charging

Fume evolution at charging decrease, approx. 8 to 10 times

Organic pollutants emission decrease, > 99 %

Mercury emission decrease, > 80 % (Option)

Resultant CO2 emission decrease, > 100 kg/ton steel

   

 

Dr. Alberto Fragiacomo

 ITALY - North-East-Veneto; Winter Local Time: GMT+1

Mob.:  +39 347 2618940 ;  Email: wemes@wemes.it   
Update the: 10 febbraio 2021