Question 11 QMED04 - Boiler Technician-Watertender

The Correct Answer is D **Explanation for D (scrubber):** A scrubber is a specialized type of gas cleaning device designed to remove pollutants from a gas stream, often by bringing the gas into contact with a liquid (usually water or a chemical solution). In the context of an inert gas system (often used on ships, particularly tankers), the inert gas is typically produced by burning fuel and then processing the exhaust. This exhaust contains solid soot (combustion products) and gaseous sulfur compounds (sulfur dioxide, $\text{SO}_2$). The scrubber performs the dual function mentioned: 1. **Cleaning/Purifying:** It uses the scrubbing water to wash out solid particles (soot) and absorb soluble gaseous impurities like $\text{SO}_2$. 2. **Cooling:** The scrubbing water, which is typically supplied cool, directly cools the hot inert gas down to a safe operating temperature. **Why Options A, B, and C are incorrect:** * **A) cooler:** While the device performs cooling, the term "cooler" generally refers only to heat exchange equipment (like a radiator or heat exchanger) that primarily changes temperature. It does not encompass the essential cleaning/purifying function of removing both solid particles and gaseous contaminants necessary for this specific application. * **B) filter:** A filter is primarily designed to remove solid particles from a fluid (gas or liquid) by mechanical separation (like a mesh or porous material). It is effective against soot, but it is not typically designed to simultaneously cool the gas significantly, nor is it effective at removing or absorbing gaseous contaminants like sulfur dioxide. * **C) purifier:** "Purifier" is a general term for any device that cleans a substance. While a scrubber *is* a type of purifier, "scrubber" is the specific and most technically accurate term used in industrial and marine engineering for a device that achieves both the simultaneous cleaning (solids and gas) and cooling of a combustion-derived inert gas stream using a liquid medium.