Statistical modeling and optimal energy distribution of cogeneration units by genetic algorithms

Our main objective is to evaluate the performance of a new method to optimize the energy management of a production system composed of six cogeneration units using artificial intelligence. The optimization criterion is economic and environmental in order to minimize the total fuel cost, as well as the reduction of polluting gas emissions such as COx, NOx and SOx. First, a statistical model has been developed to determine the power that the cogeneration units can provide. Then, an economic model of operation was developed: fuel consumption and pollutant gas emissions as a function of the power produced. Finally, we studied the energy optimization of the system using genetic algorithms (GA), and contribute to the research on improving the efficiency of the studied power system. The GA has a better optimization performance, it can easily choose satisfactory solutions according to the optimization objectives, and compensate for these defects using its own characteristics. These characteristics make GA have outstanding advantages in iterative optimization. The robustness of the proposed algorithm is validated by testing six cogeneration units, and the obtained simulation results of the proposed system prove the value and effectiveness of GA for efficiency improvement as well as operating cost minimization.

Apatite-staffelite ore flotation efficiency improvement using two-stage slurry thickening

The studies were performed suggesting that the cause of P2O5 losses during apatite-staffelite ores (ASO) treatment are due to non-selective flocculation of fine classes during flotation. When using strong flocculants, special preparation of condensed slurries is necessary, ensuring their deflocculation before the flotation process. A scheme and mode of preparation of fine classes for the flotation process have been developed, including thickening of the classification overflows using strong anionic flocculants and deflocculation of the thickened product before the flotation process with reagents-dispersants used in the basic flotation mode. A mode of preparation of slimes of ASO ores for flotation is proposed, including thickening of the discharge of the classification operation using the anionic flocculant “Praestol-2540”, conditioning of the condensed product with additions of liquid glass and caustic soda in a ratio of 1 : 1, dilution and re-thickening of deflocculated slimes, consolidation and flotation thickened sludge and sand. The big laboratory tests have shown that the application of the developed regime provides a total increase in the extraction of P2O5 from ore from 70,1 to 71,5 % with an increase in the P2O5 content in apatite concentrate from 37,1 to 37,8 %, which makes the developed technology promising for processing refractory ASO at Kovdorsky GOK.

Effect of quartz aperture covers on the fluid dynamics and thermal efficiency of falling particle receivers

Falling particle receivers are an emerging technology for use in concentrating solar power systems. In this work, quartz half-shells are investigated for use as full or partial aperture covers to reduce receiver thermal losses. A receiver subdomain and surrounding air are modeled using ANSYS® Fluent®. The model is used to simulate fluid dynamics and heat transfer for the following cases: (1) open aperture, (2), aperture fully covered by quartz half-shells, and (3) aperture partially covered by quartz half-shells. We compare the percentage of total incident solar power lost due to conduction through the receiver walls, advective losses through the aperture, and radiation exiting the aperture. Contrary to expected outcomes, results show that quartz aperture covers can increase radiative losses and result in modest to nonexistent reductions in advective losses. The increased radiative losses are driven by elevated quartz half-shell temperatures and have the potential to be mitigated by active cooling and/or material selection. Quartz half-shell total transmissivity was measured experimentally using a radiometer and the National Solar Thermal Test Facility heliostat field. Average measured total transmissivities are 0.97±0.01 and 0.94±0.02 for concave and convex side toward the heliostat field, respectively. Quartz half-shell aperture covers did not yield expected efficiency gains in numerical results due to increased radiative losses, but efficiency improvement in some numerical results and the performance of quartz half-shells subject to concentrated solar radiation suggest quartz half-shell aperture covers should be investigated further.

A Study on the Efficiency Analysis of Global Terminal Operators Based on the Operation Characteristics

Shipping and port industries are undergoing rapid environmental changes because of the reorganization of carrier alliances, enlargement of ships, and an increase in global uncertainty. Thus, the sustainable operation of container terminals requires a new assessment of port efficiency and measures to enhance efficient operation. Hence, we classified 21 global terminal operators (GTOs) into stevedore, carrier, and hybrid GTOs based on their operation characteristics and derived a sustainable container terminal operation method using data envelopment analysis efficiency and Malmquist productivity index analysis. The results showed that stevedore GTOs exhibited improved efficiency when the terminal infrastructure was expanded. However, the returns to scale and technical change factors in the productivity change trend decreased. Meanwhile, the objective of carrier GTOs is cost reduction, unlike stevedore and hybrid GTOs, which focus on generating profits. Consequently, carrier GTOs were the most inefficient with little intention to improve efficiency. A systematic efficiency improvement strategy through the acquisition of a terminal share was effective for hybrid GTOs. However, similar to stevedore GTOs, investment in technical change was insufficient for hybrid GTOs. The efficiency analysis we conducted for each operation characteristic is expected to provide useful basic data for establishing efficiency improvement strategies for every GTO.