Читать книгу Engineering Solutions for CO2 Conversion - Группа авторов - Страница 46

3.3.2 Application Concepts of OTMs for Carbon Capture and Storage (CCS)

Оглавление

As already stated for the application of CCS strategies, OTMs are considered as O2 supply units for the conduction of combustion processes. In that way, an OTM module is integrated within an industrial process following approaches that use waste heat streams for heating up the module to its operation temperature (typically 800–900 °C). Therefore, the operation and integration can be done according to two different configurations, known as 3‐end and 4‐end modes (Figure 3.5a,b). These modes differ mainly on the number of streams connected to the OTM module. As can be seen in Figure 3.5a, the 4‐end mode uses a fraction of the flue gas (mainly consisting of CO2 and H2O) from the burner for heating the module and for performing O2 separation as a sweeping agent. As already pointed out, the recirculation of flue gases increases the plant efficiency, also reducing O2 production costs due to the highly synergetic thermal integration of OTM modules in the process. Differently, in the 3‐end mode, any contact between flue gases and membrane materials is avoided. In this configuration, O2 is extracted using a vacuum pump at the permeate side, thus obtaining a pure O2 stream that is used for combusting the fuel. The thermal integration is done by heating the air feed stream with heat exchangers where the heat is transferred from the exiting flue gases. This operation mode is considered for the cases where membrane material cannot operate under flue gas atmospheres. The selection of one or another configuration will influence parameters such as module design (especially the required membrane surface area) and plant layout, also determining the overall plant efficiency [52, 53]. Nevertheless, there is no preferred mode for conducting the OTM module integration. This can be observed in the OTM developments carried out by Praxair [54] and Air Products and Chemicals Inc. [55] (the most advanced up to date), which consider 4‐end and 3‐end operation modes, respectively.

Engineering Solutions for CO2 Conversion

Подняться наверх