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Open AccessArticle

Model-Based Quality, Exergy, and Economic Analysis of Fluidized Bed Membrane Reactors

by Tabassam Nafees, Adnan Ahmed Bhatti, Usman Khan Jadoon, Farooq Ahmad, Iftikhar Ahmad, Manabu Kano, Brenno Castrillon Menezes, Muhammad Ahsan and Naveed ul Hasan Syed

Membranes 2021, 11(10), 765; https://doi.org/10.3390/membranes11100765 - 3 Oct 2021

Cited by 4 | Viewed by 4017

Abstract

In petroleum refineries, naphtha reforming units produce reformate streams and as a by-product, hydrogen (H₂). Naphtha reforming units traditionally deployed are designed as packed bed reactors (PBR). However, they are restrained by a high-pressure drop, diffusion limitations in the catalyst, and radial and axial gradients of temperature and concentration. A new design using the fluidized bed reactor (FBR) surpasses the issues of the PBR, whereby the incorporation of the membrane can improve the yield of products by selectively removing hydrogen from the reaction side. In this work, a sequential modular simulation (SMS) approach is adopted to simulate the hydrodynamics of a fluidized bed membrane reactor (FBMR) for catalytic reforming of naphtha in Aspen Plus. The reformer reactor is divided into five sections of plug flow reactors and a continuous stirrer tank reactor with the membrane module to simulate the overall FBMR. Similarly, a fluidized bed reactor (FBR), without membrane permeation phenomenon, is also modelled in the Aspen Plus environment for a comparative study with FBMR. In FBMR, the continuous elimination of permeated hydrogen enhanced the production of aromatics compound in the reformate stream. Moreover, the exergy and economic analyses were carried out for both FBR and FBMR. Full article

(This article belongs to the Special Issue Hydrogen Production and Purification with Membrane Systems)

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16 pages, 4199 KB

Open AccessArticle

Design and Development of Novel Continuous Flow Stirred Multiphase Reactor: Liquid–Liquid–Liquid Phase Transfer Catalysed Synthesis of Guaiacol Glycidyl Ether

by Nikhil H. Margi and Ganapati D. Yadav

Processes 2020, 8(10), 1271; https://doi.org/10.3390/pr8101271 - 10 Oct 2020

Cited by 3 | Viewed by 4415

Abstract

Phase transfer catalysed (PTC) reactions are used in several pharmaceutical and fine chemical industrial processes. We have developed a novel stirred tank reactor (Yadav reactor) to conduct batch and continuous liquid–liquid–liquid (L-L-L) PTC reactions. The reactor had a provision of using three independent stirrers for each phase, thereby having complete control over the rate of mass transfer across the two interfaces. In the continuous mode of operation, the top and bottom phases were continuously fed into the reactor while the middle phase was used as a batch. All three stirrers were used independently, thereby having independent control of mass transfer resistances. The reactor in a batch mode showed higher conversion and selectivity compared to a conventional batch reactor. L-L-L PTC reaction in the continuous mode was successfully performed without loss of the middle catalyst phase and with steady conversion and selectivity. The reaction of guaiacol with epichlorohydrin was conducted as a model reaction, with a 76% conversion of epichlorohydrin, 85% selectivity of guaiacol glycidyl ether, and the middle catalyst phase was stable throughout the process. Full article

(This article belongs to the Special Issue Industrial Chemistry Reactions: Kinetics, Mass Transfer and Industrial Reactor Design)

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13 pages, 1304 KB

Open AccessArticle

Experimental Investigation of Substrate Shock and Environmental Ammonium Concentration on the Stability of Ammonia-Oxidizing Bacteria (AOB)

by Hareef Ahmed Keerio and Wookeun Bae

Water 2020, 12(1), 223; https://doi.org/10.3390/w12010223 - 13 Jan 2020

Cited by 16 | Viewed by 3461

Abstract

A wastewater treatment plant (WWTP) frequently encounters fluctuation in ammonium concentration or flow rate (Q), which may affect the stability of ammonium oxidizing bacteria (AOB). In this study, two continuous stirred tank reactors (CSTRs) were operated for 588 days and ammonium concentration was varied at various steady-state conditions. There was no inhibition observed in CSTR operation and AOB acclimated once at a certain ammonium concentration. Cells at an acclimated steady-state concentration (200 mgTAN/L from R(A) and 1000 mgTAN/L from R(B)) were extracted to perform a batch test at operating conditions, and self-inhibition behavior was observed in the batch reaction. In CSTR operation, the environmental ammonium concentration was varied and the specific oxygen uptake rate (SOUR) value was estimated from daily profile data and compared with batch reaction. In the CSTR operation as a substitute for self-inhibition, the SOUR was shifted towards the maximum specific oxygen uptake rate (SOUR_max) and no self-inhibition was observed. For further justification of the CSTR’s stability, several total ammonium nitrogen (TAN) concentrations (range from ~−106 to ~+2550 mgTAN/L) were directly added to interrupt the stability of the process. As a substitute for any effect on the SOUR, the CSTRs were recovered back to the original stable steady-state conditions without varying the operational conditions. Full article

(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)

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