Operation of a Solid Oxide Fuel Cell Reactor with Multiple Stacks in a Pressured System with Fuel Gas Recirculation

Abstract

Large‐scale modular solid oxide fuel cell (SOFC) reactors composed of multiple stacks are regarded as an efficient form of power generation and important for the global energy transition. However, such an arrangement leads to several operational challenges, and methods are required for handling such challenges and understanding their sources. Hence, a test rig for the examination of a 30 kW SOFC reactor with multiple stacks, for operation near real system conditions, is built. The test rig, which allows operation at elevated pressure, is equipped with a high‐temperature blower that recirculates the fuel gas at SOFC reactor temperature. In a measurement campaign, fuel gas, reactant conversion, and pressure are varied in stationary and transient experiments. The experimental results showed that the operating conditions of the individual stacks of large SOFC reactors vary largely due to flow distribution and heat losses. Methods for the investigation of these critical characteristic parameters are derived from the experimental results. Furthermore, the impact of pressurization and fuel gas recirculation on the SOFC reactor is analyzed. This publication shows the need to understand the behavior of large SOFC reactors with multiple stacks to increase the performance and robustness of complete process systems.

Operation strategies for a flexible megawatt scale electrolysis system for synthesis gas and hydrogen production with direct air capture of carbon dioxide

“…The high temperature heat exchangers for recuperation are modelled as counterflow plate heat exchangers using a 1D approach. The parameters were derived from heat exchangers of experimental setups 11 and adapted to the system studied here. For the air heat exchanger this results in a product of the heat transfer coefficient and surface at the design point of kA = 236 W K −1 and a heat capacity of C = 481 J K −1 .…”

“…9,10 However, for SOFC systems also, research on reactors is rare. 11 In this study, DLR's transient modelling framework TEMPEST 12,13 is used, which is described in the Methodology section and allows detailed coverage of all stacks in modular SOC reactors as well as analysis of the complete process system. Here, a model of a commercial SOC reactor with 24 stacks is utilized, which was parameterized and validated 13 based on experiments on DLR's SOEC test rig named GALACTICA with a maximum electrical power of 120 kW.…”

A New Approach to Modeling Solid Oxide Cell Reactors with Multiple Stacks for Process System Simulation

“…Therefore, system studies often assume SOC reactors to be assemblies of identically behaving cells and stacks. Experiments showed that this is not the case, [10][11][12] leading to an overestimation of z E-mail: marius.tomberg@dlr.de system performance and underestimation of potentially damaging operation. 13 Therefore, simulations to understand reactor behavior, to monitor and improve operation as well as robustness are advisable.…”

“…The authors have shown before [10][11][12] that each stack in an SOC reactor operates in a different operating point due to heat losses, operating currents and uneven flow distribution of the gases. Implications like spatial and temporal temperature gradients inside these stacks need to be analyzed to ensure high performance and reliability.…”