What is the purpose of sidewall tubes or water wall tubes?

The primary purpose of sidewall tubes, also referred to as water wall tubes, is to cool and protect the sidewalls of the furnace, which is crucial in maintaining the structural integrity and operational efficiency of the boiler or furnace system. These tubes are typically filled with water, which absorbs heat from the combustion gases. This process helps to prevent overheating of the furnace walls, which could lead to damage or failure of the furnace structure.

Additionally, as the water in these tubes is heated, it turns into steam. This not only serves the purpose of cooling but also contributes to the overall steam generation within the system. However, the fundamental role of the sidewall tubes is mainly to protect the sidewalls rather than primarily to generate steam or provide support, which are functions associated with other components in the system. Enhancing combustion efficiency is also not their primary purpose, although maintaining the furnace's integrity can indirectly support optimal combustion conditions.