A procedure for design of hydrogen networks with multiple contaminants

It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the design procedure, the precedence of processes is determined by the values of concentration potential of demands.The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to illustrate the effectiveness of the method. It is shown that the design procedure has clear engineering meaning.

Locally Isolated Bacterial Strains with Multiple Degradation Potential Capabilities on Petroleum Hydrocarbon Pollutants

In the present study, 23 isolates, dominated by bacterial genera (74%) were isolated from petroleum sludge at refinery wastewater plant, Jeddah, KSA, by means of selective enrichment in nutritionally optimized refinery wastewater (NORWW) and over twelve successive transfers. Efficiency of biodegradation on complex mixture of hydrocarbons present in refinery wastewater was evidenced by changes in both total viable counts (TVC) and COD content of cultivation broth. Out of the 23 isolates three most potent isolates named BDCC-TUSA-8, BDCC-TUSA-12 and BDCC-TUSA-18 were selected for their efficient COD removal and active growth. The three isolates were tested separately in Bushnell-Haas (BH) media for their capabilities to degrade n-Hexadecane, phenol and phenanthrene, representing the major types of hydrocarbon pollutants. The results strongly indicated that all three isolates showed multiple degradation potentials with remarkably fast reaction rates. Before being recommended for future work, the three isolates were fully characterized and identified employing culture-dependent techniques such as API 20E, API 20NE and API 50CHB, and further confirmed by partial 16S rRNA gene sequencing and phylogenetic analysis as Pantoea agglomerans, Acinetobacter lwoffii and Bacillus thuringiensis respectively. The obtained potent strains provide valuable candidates if assemblages of mixed fewer strains with overall broad and complementary enzymatic capacities are to be considered in order to bring the rate and extent of petroleum biodegradation further as a cost-effective process.

Multiple solutions and stability of the steady transonic small-disturbance equation

Numerical solutions of the steady transonic small-disturbance（TSD） potential equation are computed using the conservative Murman-Cole scheme. Multiple solutions are discovered and mapped out for the Mach number range at zero angle of attack and the angle of attack range at Mach number 0.85 for the NACA 0012 airfoil. We present a linear stability analysis method by directly assembling and evaluating the Jacobian matrix of the nonlinear finite-difference equation of the TSD equation. The stability of all the discovered multiple solutions are then determined by the proposed eigen analysis. The relation of stability to convergence of the iterative method for solving the TSD equation is discussed. Computations and the stability analysis demonstrate the possibility of eliminating the multiple solutions and stabilizing the remaining unique solution by adding a sufficiently long splitter plate downstream the airfoil trailing edge. Finally, instability of the solution of the TSD equation is shown to be closely connected to the onset of transonic buffet by comparing with experimental data.