A wet mixing process is proposed for filled rubber composites with a high silica loading to overcome the drawbacks of high energy consumption and workplace contamination of the conventional dry mixing process. Ball milling was adopted for preparing the silica dispersion because it has a simple structure, is easy to operate, and is a low-cost process that can be easily scaled up for industrial production. The response surface methodology was used to optimize the making of the silica dispersion. The optimum conditions for a well-dispersed silica suspension with the smallest silica particle size of 4.9 mm were an about 22% silica content and 62 h of ball milling. The effects of dry and wet mixing methods on the properties of silica-filled rubber composites were investigated in a broad range of silica levels from low to high loadings. The mixing method choice had little impact on the properties of rubber composites with low silica loadings. The silica-filled rubber demonstrated in this study, however, shows superior characteristics over the rubber composite prepared with conventional dry mixing, particularly with high silica loadings. When compared to silica-filled natural rubbers prepared by dry mixing (dry silica rubber, DSR), the wet mixing (for WSR) produced smaller silica aggregates with better dispersion. Due to the shorter heat history, the WSR exhibits superior curing characteristics such as a longer scorch time (2.2–3.3 min for WSR and 1.0–2.1 min for DSR) and curing time (4.1–4.5 min for WSR and 2.2–3.1 min for DSR). Additionally, the WSR has superior mechanical properties (hardness, modulus, tensile strength, and especially the elongation at break (420–680% for WSR and 360–620% DSR)) over the DSR. The rolling resistance of WSR is lower than that of DSR. However, the reversed trend on the wet skid resistance is observed.

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Abstract. Under the 20122050, the International Energy Agency (IEA) and the World Business Council for Sustainable Development (WBCSD) have developed a roadmap for the reduction of energy and carbon intensities in cement production. The aim of this research is to study and evaluate the energy consumption (EN), global warming potential (GWP) impact, and economic assessment of Portland cement production. It was found that the total EN and GWP of conventional process were 3.29 GJ per ton of Portland cement and 0.76 ton CO2 equivalent per ton of Portland cement, respectively. The total cost was 1,346 THB per ton of Portland cement. The largest contribution was from fossil fuels used and the limestone calcination in clinker production which produced the total EN of 83.63% and the total GWP of 91.36%, and the total cost of 63%. In addition, the production of Portland cement was environmentally improved by using low carbon fuels, increasing of alternative fuels to fossil fuels ratio, and increasing of pozzolan to cement ratio. The results showed that all improvements significantly reduce the total EN, GWP, and the total cost. When the using of low carbon fuels, the increasing of alternative fuels to fossil fuels ratio, and the increasing of pozzolan to cement ratio, the EN, GWP, and the total cost were decreased by 1.68%, 18.33%, and 4.39% of the total EN and by 25.35%, 3.06%, and 10.45% of the total GWP, and by 4.6%, 4.12%, and 10.64% of the total cost, respectively.

Circulating fluidized bed downer reactors (downer reactors) exhibit good heat and mass transfer, and the flow behavior approaches the ideal plug flow.

The effects of operating conditions and scaling-up on reactor temperature control and performance in propylene polymerization fluidized bed reactors were studied by phenomenological and CFD models.

Stirred tanks are prevalent in various industries, including chemical, biochemical, and pharmaceutical industries. These reactors are suitable for ensuring efficient mass and heat transfer because adequate mixing can be achieved. Numerous studies have been conducted on small-scale stirred-tank reactors. However, upscaling such reactors is challenging because of the complex flow behavior inside the system, especially for the mixing of immiscible liquid–liquid systems. Thus, the objectives of this study were to examine the flow behavior and upscale an immiscible liquid–liquid stirred tank using CFD simulation by investigating a flat-bottomed stirred tank reactor, equipped with a six-blade Rushton turbine. The simulated results were in good agreement with those obtained experimentally. The scale of the reactor significantly affects the hydrodynamic behavior, and the uniformity of the radial distribution of the velocity decreases with increasing Reynolds number. Furthermore, the upscaling criteria were evaluated for geometric similarity and equal mixing times. The proposed scaling law reliably scaled up the immiscible liquid–liquid mixing in a stirred tank with a difference in the range of ±10%.

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