Goodfellow EFSOP Project at ASW Sheerness Steel

Category: Industry and Manufacturing

Stantec Consulting Ltd., Mississauga, Ont. and ASW Sheerness Steel Ltd.

The inside of a steel mill is one of the most hostile environments on earth. Extreme heat and noxious gases make working conditions hazardous and difficult. The situation makes it hard for operators to get an insight into what is going on during much of the heating process, so until now it has been mostly treated as a black box. Operators adjusted more than 70 variables that affect the quality of the steel, and based their adjustments on their years of experience. They were unable to gauge their success until the quality of the final product was tested. As a result, the steel’s quality varied greatly from crew to crew, and even from heat to heat when made by the same crew.

EFSOP, an acronym for Expert Furnace System Optimization Process, has changed the rules. Using a patented water cooled probe in the exhaust port, the Goodfellow EFSOP system compares data about the chemistry of the exhaust gases with data from the process derived from the plant’s operational control system. All this is done in real time.

The installation at the ASW (formerly Co-Steel) Sheerness plant on the isle of Sheppey in southeast England is the latest version of the technology. Developed in Canada by Goodfellow Technologies (now Stantec) with financial support from Natural Resources Canada, the Ontario Ministry of the Environment and Co-Steel Lasco, EFSOP will save the Sheerness plant more than a million dollars a year in energy costs and increased productivity. At the same time the technology significantly reduces greenhouse gases and the risk of explosions.

Heat cycles

The fume systems for electric arc furnaces have traditionally been designed based on simple engineering models that were little more than rules of thumb for estimating the peak heat loads required by the process. Thus the fume system was designed to operate at its peak temperature for the entire heat cycle. By analyzing the chemistry of the furnace’s exhaust gases, researchers discovered that the heat cycle was divided into a number of significant stages based on process events.

Now that they had accurate real time data about conditions inside the furnace, operators could make adjustments to various inputs and optimize the process. Researchers were able to learn from experienced operators by developing profiles of operator practices through the heat cycle. These profiles were used to develop standard operating modes that gave more consistent product quality, as well as improved efficiency and productivity.

EFSOP thus leverages the information gained from thousands of heat profiles recorded under actual steel plant conditions to optimize the process of electric arc furnace steel making. This optimization results in a significant saving of electrical energy and improves productivity roughly five per cent. It also reduces carbon monoxide (CO) and volatile organic compounds (VOC) emissions without the need for anti-pollution devices that are expensive and can limit production.

As an information based system, EFSOP requires very little in the way of capital improvements. By using the electric controls already found within the steel plant and the gas chemistry analysis provided by the probe and gas analysis system, EFSOP uses computer algorithms to optimize an existing electric arc furnace’s operations. Its low capital cost and easy installation into existing steel mills results in a typical payback of three to nine months.

The technology was initially developed at the Co-Steel Lasco plant in Whitby, Ontario which has been successfully operating since 1995. To date more than 15 permanent or portable EFSOP projects have been executed worldwide.

Sheerness, U.K. installation

The ASW Sheerness Steel installation of EFSOP incorporates the most recent closed loop algorithms and neural net predictive technology.

With a production capacity of one million tonnes per year, the plant is one of the most efficient and progressive steel producers in the world. It specializes in hot rolled bars, coiled rods, sections for automotive engineering, wire drawing, structural and reinforcement.

The ASW Sheerness project consists of two electric arc furnaces. Furnace B is conventional and Furnace C is a newer shaft type. The furnaces already had off-gas analysis systems and individual burner controls but were experiencing maintenance problems. A caster upgrade in 1998 required that the EFSOP installation proceed in phases, starting with Furnace C followed by Furnace B.

With Furnace B off-line for an extended period, operators needed to “push” Furnace C without creating unsafe or inefficient conditions. After the installation of Furnace C was completed in 1998, the EFSOP system increased productivity roughly five per cent without compromising safety.

This productivity gain was achieved by the innovative closed-loop concept and a proprietary neural network model that gave predictive control over the furnace operations.

The project was done over a 12 month period with built-in flexibility and designed to accommodate plant operations. In the middle of the work the plant was sold to a new owner which affected the schedule while the new owner reviewed plant operations. Even with these challenges, both installations were completed in 1998 at a cost within five per cent of the original budget.

The ASW Sheerness project has shown that the EFSOP system can deliver a 15 to 25 kWh/ton energy savings in the operation of an electric arc furnace. This reduction minimizes the indirect generation of CO2 by reducing the load on electric power generators. Significant reductions in emissions of other greenhouse gases are also possible. EFSOP is capable, for example, of accurately measuring the NOx concentrations both at the furnace exit and end of water cooled duct. This knowledge can be useful in negotiating permitting targets, while also making it possible to correlate NOx generation patterns with furnace practices.

Of particular concern to regulatory agencies around the world is the release of carbon monoxide from electric arc furnaces, which is due to incomplete combustion of fuel. EFSOP compares upstream and downstream CO concentrations to determine if too little or too much combustion air is being introduced, and by quantifying this way can improve the furnace’s energy use and reduce emissions.

Award winners: Stantec Consulting Ltd. and ASW Sheerness Steel Ltd. Project team leaders: Howard D. Goodfellow, P.Eng., Euan Evenson, P.Eng., Michael Kempe, P.Eng., Joseph Maiolo, P. Eng. Client/owner: ASW Sheerness Steel. John Clayton, managing director