Modelling of multicomponent gas separation with asymmetric hollow fibre membranes—methane enrichment from biogas

Abstract

A mathematical model for the dynamic performance of gas separation with high flux, asymmetric hollow fibre membranes was developed considering the permeate pressure build-up inside the fibre bore and cross flow pattern with respect to the membrane skin. The solution technique provides reliable examination of pressure and concentration profiles along the permeator length (both residue/permeate streams) with minimal effort. The proposed simulation model and scheme were validated with experimental data of gas separation from literature. The model and solution technique were applied to investigate dynamic performance of several membrane module configurations for methane recovery from biogas (landfill gas or digester gas), considering biogas as a mixture of CO 2 , N 2 and CH 4 . Recycle ratio plays a crucial role, and optimum recycle ratio vital for the retentate recycle to permeate and permeate recycle to feed operation was found. From the concept of two recycle operations, complexities involved in the design and operation of continuous membrane column were simplified. Membrane permselectivity required for a targeted separation to produce pipeline quality natural gas by methane-selective or nitrogen-selective membranes was calculated.

Modeling and Simulation of Industrial Gas Permeators Accounting for Vapor Phase Nonideality

“…Before applying the developed model to describe industrial operation data, literature data under similar conditions were modeled using the same equations, to verify whether the proposed model did result in an improved description of the unit operation. The following sets of experimental data were considered: Pan, Giglia et al, and Coker et al These sets of experimental data were chosen as they have been extensively used to validate models, e.g., by Scholz et al, Marriott et al, Cruz et al, Chowdhury et al, Katoh et al, and Kundu et al For this validation, the permeator was considered isothermal, and no effect related to heat exchange was considered. Thus, for this preliminary validation, only the equations related to the mass balance and the diffusion (including vapor-phase nonideality) were considered.…”

A Mathematical Model of Membrane Gas Separation with Energy Transfer by Molecules of Gas Flowing in a Channel to Molecules Penetrating this Channel from the Adjacent Channel

“…The multicomponent approach to numerical resolution of the membrane separation of gases problem was applied also in the work of Kundu et al (2013). In this work, additionally, recirculation of a part of streams was introduced within the framework of one membrane module.…”

Simulação De Módulos Industriais De Membranas Para Separação De Misturas Co2/Ch4

“…O dióxido de carbono (CO 2 ), um gás quimicamente considerado inerte, quando associado à água livre ocasiona aumento na taxa de corrosão; tanto nos equipamentos de superfície quanto nos dutos de exportação de gás (Engelien, 2004). Além disso, ambientalmente é considerado um dos principais responsáveis pelo efeito estufa (Deng e Hagg, 2010;Nakao et al 2009;Kundu et al, 2013). Nos campos mais antigos, o gás natural apresenta teores de CO 2 em torno de 5% em volume, nível adequado para o tratamento em torres de absorção com aminas (usualmente monoetanolamina -MEA) (Baker e Lokhandwala, 2008;Gadelha et al, 2012), entretanto, nas jazidas na região denominada de Pré-Sal, os teores médios de CO 2 dos campos do Pré-Sal estão sendo encontrados na faixa de 8% a 45% em volume.…”

“…Alternativamente, os processos de separação de gases por membranas vêm sendo bastante considerados para a remoção de CO 2 do gás natural no cenário do Pré-Sal (Deng e Hagg, 2010;Nakao et al 2009;Gadelha et al, 2012;Kundu et al, 2013). Trata-se de um processo bastante atrativo para uso offshore, dada a sua simplicidade de operação e manutenção (não possui partes móveis), robustez, baixo peso, baixa demanda de área de montagem e custos atrativos, especialmente em correntes de gás natural com elevado teor de CO 2 (Baker e Lokhandwala, 2008;Nakao et al 2009).…”

“…Recentemente a PNBV, subsidiária da Petrobras, contratou o fornecimento de sistemas de membranas a base de acetato de celuloce para processar gás natural offshore, deixando ainda em aberto, em um primeiro momento, apenas questões envolvendo a configuração das plantas que serão adotadas em suas plataformas do Pré-Sal. Alguns trabalhos da literatura têm explorado tais estratégias tanto neste cenário (Nakao et al 2009;Gadelha et al, 2012), quanto em outros, tal como no tratamento do biogás (Deng e Hagg, 2010;Kundu et al, 2013). Em particular, o trabalho de Gadelha et al (2012), indica que uma combinação da tecnologia de membranas combinadas com absorção com aminas apresenta-se como alternativa economicamente promissora para atender as especificações do Pré-Sal brasileiro.…”