A gasifier system is provided that includes a gasification chamber spool that has a ceramic matrix composite (CMC) liner adapted to form a solidified slag protective layer on an interior surface of the liner from molten slag flowing through the gasification chamber spool. The gasification system additionally includes a heat exchanger (HEX) quench spool that also includes a CMC liner adapted to form a solidified slag protective layer on an interior surface of the liner from molten slag flowing through the HEX quench spool. Additionally, the HEX quench spool includes a parallel plate HEX core having a plurality of CMC panels. The CMC panels are adapted to form a solidified slag protective layer on exterior surfaces of each respective CMC panel from molten slag flowing through the HEX quench spool. Furthermore, each CMC panel includes a plurality of internal coolant channels adapted to exchange sensible waste heat from the hot product flowing through the HEX quench spool with a coolant flowing through the internal coolant channels. The sensible waste heat absorbed by the coolant is recovered by the gasification system by utilizing the heated coolant in various operational phases of the gasification system.