Showing papers by "Daniel Tondeur published in 2008"

Optimisation-based simulation of a pressure swing adsorption process

Abstract: In this paper, an optimisation-based approach is developed for the determination of the cyclic steady-sate (CSS) of a pressure swing adsorption process (PSA). It consists in treating the simulation problem as a single dynamic optimisation problem where the performance index is the CSS condition, the decision variables are the state variables at the start of the cycle and the constraints are given by the process model equations with associated initial conditions. The resulting optimisation problem is solved using a gradient-based non linear programming (NLP) method, e.g. SQP method, where the gradients are computed by means of four different methods: finite differences, numerical and analytical sensitivities and adjoint system methods.

Carbon Capture and Storage for Greenhouse Effect Mitigation

Abstract: Publisher Summary The capture of carbon dioxide from flue gases of industrial combustion processes and its storage in deep geological formations is now being seriously considered as one of the options for mitigating climate change. This chapter presents the overall background on which this approach is based, then reviews the different capture technologies and finally discusses the different options for underground storage. Carbon dioxide is responsible for about 60% of the present-day additional radiative forcing in the atmosphere. CCS has an important and inevitable energy cost, implying that when it is applied, more primary energy is needed and, ultimately, more CO2 is generated to produce a given amount of final energy. Carbon dioxide capture has been applied to industrial gas streams for almost a century, for process purposes but not for storage purposes. The main applications were “sweetening” of natural gas and treatment of “synthesis gas” for the manufacture of ammonia and methanol. In the present context, CO2 captures producing a concentrated stream of CO2, suitable for transport and subsequent storage, starting with dilute effluents. There are a number of potential geological reservoirs that can be considered as storage options for captured CO2. These storage options include depleted oil and gas fields, CO2 enhanced oil recovery (EOR), CO2 enhanced gas recovery (EGR), CO2 enhanced coal-bed methane recovery (ECBM), deep saline aquifers and other storage options. There is little experience of combining capture, transport and storage of CO2 in a fully integrated system, and none applied to large-scale power plants.

Co-diffusion with a slow species in zeolites: cyclic experimentation and advanced modeling

Abstract: In this study, a new experimental method based on cyclic breakthrough curves is presented, in order to estimate the co-diffusion coefficients for mixtures at high adsorption loadings. For this purpose, cyclic liquid phase breakthrough curves of mixtures of 2-methylpentane 3-methylpentane (fast-diffusing species) and 2,2-dimethylbutane (slow-diffusing species) have been measured experimentally for different feed compositions at 185°C.

Some New Results From Applying Thermodynamics to Wetting Phenomena

Abstract: This contribution focuses on some non-classical aspects of capillary phenomena, mostly omitted in classical approaches, in particular the non-isothermal aspects. A systematic thermodynamic approach is proposed that allows a rigorous formulation of the governing equations in non-isothermal situations, by introducing the surface effects in the energy and entropy balances. The energetic quantities (work and heat) are calculated in a number of examples, such as adiabatic and isothermal wetting/dewetting of a porous medium, nanofluids heating, emulsion split, and new equilibrium criteria are derived were appropriate.

Contactor for thermal transfer, mixing and chemical reaction operations between fluids, comprises two arborescent networks of pipes tangled together by interleaving respective pipes, where each networks comprise successive subdivisions

Abstract: The contactor comprises two arborescent networks of pipes (A, B) tangled together by interleaving respective pipes. Each arborescent networks consists of successive subdivisions of principal pipe (CP(A), CP(B)) each leading to a higher number of smaller pipes to generate a multi-scale pipes. The contactor is present in the form of alternating subdivision stages (ES 1-ES 4) of pipes forming different networks, and interlacing stages (EL 1-EL 3) of the pipes. The structure of each network of pipes is obtained by iterative application of principal pipe of basic operations. The contactor comprises two arborescent networks of pipes (A, B) tangled together by interleaving respective pipes. Each arborescent networks consists of successive subdivisions of principal pipe (CP(A), CP(B)) each leading to a higher number of smaller pipes to generate a multi-scale pipes. The contactor is present in the form of alternating subdivision stages (ES 1-ES 4) of pipes forming different networks, and interlacing stages (EL 1-EL 3) of the pipes. The structure of each network of pipes is obtained by iterative application of principal pipe of basic operations. The pipes of two networks are in thermal contact between each other. The entanglement between the two pipes is achieved by symmetrically angled sections of the pipes, and between the two adjacent pipes is achieved by continuous rotation of a wall separating the pipes, where the wall is helical in shape. The contactor includes a first and a second supply contactor (S 2) connected in series with opposed orientation. The second supply contactor is: configured to recombine subdivided fluids interleaved between pipes by the first supply contactor (S 1); and does not mix the fluid in different network constituting the first supply contactor or allows homogenization of fluid flow flowing within different pipes thus compensating for differences in fluid loss between different paths through the network. The first and second supply contactors are separated by a section comprising parallel and non-interleaved channels and by a mixing section in which the pipes belonging to the different networks are merged. The mixing section is constituted of outlined pipes to promote mixing of fluids circulating in the section. An independent claim is included for a stereo lithographic process for fabricating the contactor.