Modeling and Optimization of Membrane Reactors for Carbon Capture in Integrated Gasification Combined Cycle Units

Abstract

This paper investigates the alternative of precombustion capture of carbon dioxide from integrated gasification combined cycle (IGCC) plants using membrane reactors equipped with H 2 -selective zeolite membranes for the water gas shift reaction. Specifically, a one-dimensional and isothermal membrane reactor model is developed. This model is used for simulation and optimization studies considering cocurrent and countercurrent modes of reactor operation. The simulation results indicate successful countercurrent cases that satisfy all of the specified targets and constraints. With use of this developed model, a novel optimization problem is formulated and solved to guide the selection of the optimal reactor design among typical scenarios of operation. The optimization results suggest as optimal solution a reactor design with a preshift followed by a membrane reactor. The obtained optimal design enables a more efficient membrane use by placing it in the optimal location. This design also results in savings of as high as 25% (in the range of 10−25%) in terms of membrane material when compared to the original membrane reactor design. For the price range of zeolite membranes considered on the order of $1000−10 000/m 2 and for large-scale applications, in which the membrane surface areas are on the order of 2000 m 2 , 25% of savings implies cost reductions on the order of millions of dollars (as high as $5 000 000 in this case).

Modeling and Optimization of High-Performance Polymer Membrane Reactor Systems for Water–Gas Shift Reaction Applications

“…This model was developed based on the WGS-MR model in [2]. A summary of the development is presented below; refer to [2] for additional detail. Assuming plug-flow operation, the membrane reactor model consists of species mole balances for co-current and counter-current cases:…”

“…An IGCC process scheme with carbon capture typically utilizes packed-bed WGS reactors followed by CO 2 removal by a Selexol process [2,3]. An alternative to this method of syngas conversion utilizes membrane reactors (MRs) equipped with H 2 -selective membranes, which grant advantages such as increased carbon monoxide (CO) conversion, facilitated CO 2 removal/sequestration (CO 2 -rich effluent is produced at high pressure), and process intensification through a reduction to the total number of process units [2,4].…”

“…Alternative reactor designs are developed by seeking to maximize reactor performance (H 2 recovery) for the minimum reactor cost as determined by the required membrane surface area. As demonstrated previously, an optimization problem is formulated to guide these designs [2].…”

“…Also available in the literature are MR models that employ H 2 -selective membranes relating to widely varied applications (see [2] for a summary for MR models, efforts and applications). A review of literature shows a few computational modeling studies based on membrane reactors employing polymeric membranes [8,9], due in part to the temperature limitations imposed by available polymers.…”

“…These studies have utilized H 2 -selective membranes (ceramic or Pd) to formulate optimization problems that examine staged membrane reactors [12][13][14] and traditional MRs [2]. In the case of the staged membrane reactors, the optimization problems were formulated with the objective of maximizing methane conversion, H 2 recovery or H 2 yield in a steam methane reforming (SMR) process employing a Pd-based membrane.…”