Frequency response of liquid fluidized systems. Part II Effect of liquid viscosity

Computer-Aided Nonlinear Frequency Response Method for Investigating the Dynamics of Chemical Engineering Systems

The Nonlinear Frequency Response (NFR) method is a useful Process Systems Engineering tool for developing experimental techniques and periodic processes that exploit the system nonlinearity. The basic and most time-consuming step of the NFR method is the derivation of frequency response functions (FRFs). The computer-aided Nonlinear Frequency Response (cNFR) method, presented in this work, uses a software application for automatic derivation of the FRFs, thus making the NFR analysis much simpler, even for systems with complex dynamics. The cNFR application uses an Excel user-friendly interface for defining the model equations and variables, and MATLAB code which performs analytical derivations. As a result, the cNFR application generates MATLAB files containing the derived FRFs in a symbolic and algebraic vector form. In this paper, the software is explained in detail and illustrated through: (1) analysis of periodic operation of an isothermal continuous stirred-tank reactor with a simple reaction mechanism, and (2) experimental identification of electrochemical oxygen reduction reaction.

Solid-liquid circulating fluidized bed: a way forward

Solid-liquid circulating fluidized beds (SLCFBs) offer several attractive features over conventional solid-liquid fluidized beds such as efficient liquid-solid contact, favorable mass and heat transfer, reduced back-mixing of phases, and integrated reactor and regenerator design. These unique features have stimulated theoretical and experimental investigations over the past two decades on transport phenomena in SLCFBs. However, there is a need to compile and analyze the published information with a coherent theme to design and develop SLCFB with sufficient degree of confidence for commercial application. Therefore, the present work reviews and analyzes the literature on hydrodynamic, mixing, heat transfer, and mass transfer characteristics of SLCFBs comprehensively. Suitable recommendations have also been made for future work in concise manner based on the knowledge gaps identified in the literature. Furthermore, a novel multistage SLCFB has been proposed to overcome the limitations of existing SLCFBs. The proposed model of SLCFB primarily consists of a single multistage column which is divided into two sections wherein both the steps of utilization viz. loading (adsorption, catalytic reaction, etc.) and regeneration of solid phase could be carried out simultaneously on a continuous mode.

Studies on the expansion characteristics of fluidised beds with silica-based adsorbents used in protein purification

In these investigations, a detailed examination of the fluid dynamic characteristics of expanded beds containing silica-based chromatographic adsorbents has been carried out. In particular, the effects of the column accessories such as distributor design and the flow-rate on the dispersion coefficient of the adsorbent particles have been examined. The experimental data have been analysed in terms of residency time effects, fluid flow characteristics and physical properties of the adsorbent particles using several different theoretical models. In common with experience of packed-bed systems, the results confirm that the optimisation of the dynamic capacities as well as the dynamic adsorption rates of adsorbents in expanded-bed systems must take into account column design characteristics as well as the physical/chemical features of the adsorbents, if the highest productivities of expanded-bed/fluidisation procedures are to be achieved with crude feedstocks from biotechnological applications.