Simulation of a mixed-conducting membrane-based gas turbine power plant for CO2 capture: system level analysis of operation stability and individual process unit degradation

Abstract

A gas turbine power plant for CO 2 capture, based on oxygen-permeable membranes with mixed ionicelectronic conductivity, was analysed with respect to longterm stability by means of numerical simulation. Due to the attractive transport and physicochemical properties of mixed-conducting La 2 NiO 4+δ , this nickelate was selected as a prototype membrane material for this application. Experiments showed very slow degradation of La 2 NiO 4+δ membranes at oxygen chemical potentials close to atmospheric conditions, which are associated with kinetic demixing and other microstructure-related factors. Interaction with CO 2 in the intermediate temperature range also leads to lower oxygen permeation, whilst increasing oxygen pressure may cause partial phase decomposition and microstructural changes, thus again limiting the range of possible operation conditions. The relevant operational constraints were included in a detailed membrane-based gas turbine power plant model. The membrane performance degradation with time was approximated by a linear function with average rate of 3.3% per 1,000 operation hours. Furthermore, performance deterioration of the gas turbine compressor and turbine were also considered. Simulations revealed that the power plant is substantially affected by degradation of the ceramic membranes and turbomachinery components. The already rather small operating window was further narrowed when compared with a conventional gas turbine power plant. Two different designs of the membrane-based power plant were analysed: (1) with and (2) without additional combustors (afterburners) between the membrane reactor and the gas turbine. Afterburners increase thermal efficiency as well as power output, but also lead to non-negligible CO 2 emissions. In order to have a frame of comparison, results for a conventional gas turbine power plant with degradation of turbomachinery components are also presented. Simulations representing changes in ambient temperature and fuel composition as well as failure incidents were executed to analyse the susceptibility of the gas turbine power plant to external and internal changes.

Simulation of an Oxygen Membrane-Based Gas Turbine Power Plant: Dynamic Regimes with Operational and Material Constraints

“…In reality, measured variables may vary due to measurement errors. Furthermore, the turbomachinery and the membrane reactor components are exposed to degradation, and changes in ambient conditions also have a strong effect on the power plant performance …”

Recycling process development with integrated life cycle assessment – a case study on oxygen transport membrane material

“…71,72 After the chemical failure of membranes ( e.g. , formation of carbonates or binary phases), 73–76 closed-loop chemical recycling appears favourable to fulfil the high quality and security standards. 77–79…”

“…3 End-of-life membranes would be an easily recoverable, high-quality waste with well-defined composition and valuable components. 71,72 After the chemical failure of membranes (e.g., formation of carbonates or binary phases), [73][74][75][76] closed-loop chemical recycling appears favourable to fulfil the high quality and security standards. [77][78][79] A promising Ruddlesden-Popper (RP) phase membrane material (La 0.9 Ca 0.1 ) 2 Ni 0.75 Cu 0.25 O 4±δ (LCNC) was recently developed by Chen et al 80 LCNC showed a sufficient oxygen permeation flux of 0.63 mL min −1 cm −2 at 900 °C for a 0.65 mm thick membrane under both, air/helium and air/CO 2 gradient.…”