Recent Patents on Chemical Engineering - Volume 2, Issue 3, 2009

A newly-developed fine bubble aeration system, by which air is transferred under supercavitation conditions, shows a clearly better performance than traditional, well-known aerators that rely on the jet-pump principle (Schmid & Geier, 2003). The performance can be compared to oxygen transfer rates achieved in membrane and foil plate aerators. A prototype supercavitation aerator installed at a sewage treatment plant revealed an air input rate, which was about one third lower than that of the replaced jet pump system. In spite of this low air input rate, the daily demand of pure oxygen for the additionally installed membrane aeration system went down by approximately 49 percent, from the original level of about 1 200 m3/d to about 600 m3/d - and this over a test period of more than seven months. With this new aerator and during the first three months of test phase already, more than 10 000 Euros had been saved because of the reduced pure oxygen consumption. In this article, a review of the patents on different aspects of a new aeration technology using “supercavitation” is presented.

Catalytic oxidation offers low-temperature surface conversion of hydrocarbon fuels. This feature has found several practical applications in refinements of some existing energy technologies. The current review is focused on the use of catalytic converters and processes in two energy technologies, i.e. I. gas turbines and II. radiant burners. An overview of catalytically stabilized combustion is provided which constitutes an attractive alternative to gas-phase homogeneous combustion in gas turbines since, e.g. it can stabilize flames at lower fuel-to-air ratios, thereby lowering flame temperatures and reducing NOx emission. Further, recent developments relating to catalytic oxyforming of hydrocarbon fuels prior to total combustion and some others patent categories are discussed. Furthermore, patented developments in relation to catalytic conversion in radiant burners that transform released combustion energy into infrared radiation which is useful, e.g. in drying paint are summarized. Finally, a brief comment on the future directions of the two selected energy technologies is provided.

Membrane reactors are a modern configuration which integrates reaction and separation units in one vessel and results in a tremendous degree of process intensification. Application of membrane reactors for hydrogen production has been widely studied in literature because membranes with infinite permselectivity towards hydrogen are well known since two centuries. On the other hand, the request of ultra-pure hydrogen is constantly increasing mainly due to the advances in fuel cells. For this reason, different patents have also been awarded in this field. In this review, the main aspects related to the patents on hydrogen production through membrane reactors have been reported, with particular attention to the future trend on the field.

Controlling and uniforming bottom shear stress is an important issue in many technical apparatus applied in biotechnology, chemical and process engineering, medicine and also in marine sciences. The device used in the latter application, has been referred to as microcosm, and was studied in detail in part I of this study (Khalili et al, Recent patents in Chem. Eng., 2008). The present investigation deals with quantification of the ability of shear stress uniformity achieved by two other devices known as shear stress inducers, which consist of a cone rotating in a fixed cylindrical container. In a detailed numerical study, the effect of all influencing parameters -cone angle, distance between the cone-tip and the the bottom disk, and Reynolds number- were investigated. The results confirm that the performance of shear stress inducers strongly depends on the input parameters, and that the inducers can not be regarded as a universal device to generate optimal uniformity.

Olive mill wastewater (OMW), generated by the oil extraction industry, represents a severe environmental problem due to its highly polluting organic load arising from polyphenol content with low biodegradability. However, with its more than 30 phenolic compounds, OMW is also regarded as a potent source of natural antioxidants. Consequently, during recent years, various reports have appeared in the literature following such benefit. In this article, patent publications between the years 2005 and 2009 for the recovery of phenolic antioxidants from OMW and olive processing solid by-products are reviewed: solvent extraction and membrane separations individually or integrated with some other separation and concentration procedures, such as centrifugation, chromatographic separation and evaporation are the fundamental processes described. In the publications reviewed, hydroxytyrosol, tyrosol, oleuropein and phenolic acids, which possess more powerful antioxidant properties than other phenolic compounds in OMW, are given the most prominence for their recovery. The interest in membrane technologies in processing olive oil by-products indicates that the future direction of the processes for the recovery of antioxidants from OMW is presumably toward the utilization of membranes in a sequential design.

Acidic rock drainage (ARD) is naturally produced through a series of chemical and biochemical reactions at abandoned mine sites. ARD containing acidity and a broad range of heavy metals is classified as hazardous, and must be properly treated. Many technical advances have been developed in recent years towards prediction, control, prevention, and treatment of ARD. This paper focused on the ARD treatment reviews on more than 85 patents filed mainly since year 2000. The patents surveyed are classified into four main types of ARD treatment: chemical precipitation process, adsorption method, biological system, passive treatment and others. The advanced technologies are discussed and evaluated. The key inventors and attractive applications are addressed. An assessment is made about current and future development of ARD treatment technologies.

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