- Steam Jet Draught Definition: Steam jet draught is defined as a system that uses pressurized steam to create draught in a boiler, eliminating the need for electric draught fans.
- Simple Construction: The steam jet draught system is simple to build and easy to maintain, which lowers maintenance costs.
- Forced Steam Jet Draught: This type feeds steam to the furnace entry, creating draught by dragging fresh air through the system.
- Natural Steam Jet Draught: In this type, a steam nozzle in the smoke box at the stack’s bottom creates draught by dragging flue gases.
- Advantages and Disadvantages: The system is economical and space-efficient but relies on steam production to create draught.
The boiler produces steam. When we use a small portion of this pressurized steam to create draught in the boiler, it’s called steam jet draught. Because the steam itself creates the draught, there is no need for extra electric power to run draught fans, reducing system costs. Steam jet draught is a straightforward and cost-effective draught system.
The system is simple to construct and easy to maintain, resulting in low maintenance costs. In a steam jet draught system, a small portion of generated steam exits through a nozzle. The kinetic energy of this high-velocity steam drags air or flue gases into the boiler. There are two types of steam jet draught: natural steam jet draught and forced steam jet draught.
Forced Stream Jet Draught
In forced stream jet draught, we feed a portion of the stream produced in the boiler to the entry point of the furnace through diffusion pipe. Due to the kinetic energy of steam, there will be a draught at the entry point because of which fresh air gets dragged to the grate and then to the economiser then to preheater then ultimately to the chimney.
Natural Steam Jet Draught
In this system, a steam nozzle is placed in a smoke box at the bottom of the stack. The steam forcefully enters the smoke box, dragging flue gases created in the furnace due to the kinetic energy of the steam jet. This process is called natural steam jet draught.
Steam jet draught is simple, economical, and takes up very little space. However, the main disadvantage is that draught can only be created after steam is produced.
