Simulated and experimental results on heat recovery from hot steel beams in a cooling bed applying modified solar absorbers

in Journal of Cleaner Production (2014), (68), 261-271

In recent years, the steel industry has undertaken efforts to increase energy efficiency by reducing energy consumption and recover otherwise lost heat. About 60% of the energy consumed in a steel plant ... [more ▼]

In recent years, the steel industry has undertaken efforts to increase energy efficiency by reducing energy consumption and recover otherwise lost heat. About 60% of the energy consumed in a steel plant is lost in cooling beds where the hot steel beams are cooled down by natural convection and radiation. In this paper, the potential of heat recovery by radiation in a cooling bed was determined. Firstly, numerical simulations of the heat flux were done and validated with experimental measures. Secondly, a pilot test to recover the heat with modified solar absorbers was installed at the side of the cooling bed. The standard solar panels were painted with high absorption paint in the wavelength range of the hot beams. The results showed that up to 1 kW/m2 could be recovered with a temperature of 70°C at the side of the cooling bed, with a thermal efficiency of approximately 40%. As the experimental results were promising, further research is suggested to find an adequate selective coating and glazing. This would maximize the absorption at the wavelength range of the hot beams and minimize the emissivity at operational temperature of the absorber (100°C). Additionally, it would be of interest to find the optimum position for the absorbers in the cooling bed, which maximizes the heat recovery and does not interfere in the production process. [less ▲]

Integrative analysis of the energy flow in a steel plant and a comprehensive approach to increase the energy efficiency

in Proceedings METEC InSteelCON 2011, Düsseldorf Germany, CCD Congress Center, Düsseldorf, 27.06-01.07. (2011, July)

Steel industry is a highly intensive energy consumer. The energy used by the studied electric steelmaking plant could supply 25,000 households with thermal energy and 100,000 households with electrical ... [more ▼]

Steel industry is a highly intensive energy consumer. The energy used by the studied electric steelmaking plant could supply 25,000 households with thermal energy and 100,000 households with electrical energy. Increasing the energy efficiency of a steel plant will not only have impact in the reduction of greenhouse emissions but also in an increase of the competitiveness of the plant. A Luxembourgish steel plant is studied in detail and several options for energy savings are identified. Promising energy efficiency gains can be achieved by the optimization of the electric arc furnace and the reheating furnaces and by the improvement of the logistics between the continuous casting and the reheating furnace. The possibilities of energy recovery for heating purposes and for the generation of electricity with ORC- (Organic Rankine Cycle) or KALINAtechnologies are studied. In addition there is the opportunity to deliver hot water to a near district-heating system using otherwise lost energy and creating regional synergies. Nevertheless there is a need to develop a comprehensive and integrative approach to find a good overall solution instead of treating each step separately. The University of Luxembourg in collaboration with a Luxembourgish steel plant is developing a methodology to assess the technical, economical and environmental aspects of each solution. The objective is to assist in the decision-making in the company’s energy efficiency strategy and to perform a comparative analysis of the different solutions in order to propose an optimized plant, based on its feasibility due to local restrictions and different energy price scenarios. This ideal plant will be composed of individual elements, which proved their effectiveness in different real plants, so that the approach stays applied [less ▲]