What is a method used to prevent flue gas leakage in a packaged watertube boiler?

A steel casing forms a seal for the furnace is an effective method used to prevent flue gas leakage in a packaged watertube boiler. The integrity of the combustion chamber is crucial for ensuring that the flue gases do not escape into the environment, which could lead to both safety hazards and efficiency losses.

The steel casing provides a robust barrier that contains the gases produced during combustion within the furnace area. This sealed construction helps maintain the required pressure and minimizes the risk of any flue gases escaping into the atmosphere. By preventing leakage, the system can operate more efficiently and safely, reducing the chance of combustion-based pollutants affecting the surrounding environment or personnel.

Other methods listed may play important roles in a boiler system, but they do not specifically address the prevention of flue gas leakage in the same direct manner as the steel casing. For instance, an economizer improves overall efficiency by recovering heat, smoke stacks being taller can improve draft but don't seal off gases directly, and an induced draft fan aids in maintaining combustion efficiency but again, does not create a contained environment like the casing does.