Question 71Steam Plants - Assistant Engineer

The correct answer is C) direct the flow of combustion gases. The refractory installed in a marine boiler serves to direct the flow of combustion gases through the boiler, ensuring efficient heat transfer and preventing hot spots or uneven heating. The refractory lining helps guide the gases along the desired path, optimizing the boiler's performance. The other answer choices are incorrect because they do not accurately describe the secondary function of the refractory. The refractory does not primarily support the boiler casing (A), the burner distance piece (B), or the air flow through the burner diffuser (D), but rather its key secondary function is to direct the flow of combustion gases through the boiler.