Definition - What does Continuous Blowdown mean?
This is a boiler feed water treatment process that aims to remove suspended solid impurities in a boiler to enhance heat transfer efficiency. It is also a control strategy, whereby it limits the amount of corrosion caused by these impurities. The rate of blowdown in this system helps in eliminating the levels of contamination in the boiler unit.
Corrosionpedia explains Continuous Blowdown
The common ways of doing a blowdown in a boiler are:
- The manual blowdown
- The continuous blowdown
Continuous blowdown is an automatic process that operates on set time intervals to perform the elimination process. Its continuity supersedes the manual type that encourages the accumulation of solid impurities in the boiler. This process focuses on the removal of suspended contaminants at their point of high concentration (surface). It works under control valves and taps that can hold high pressures and temperatures.
A continuous blowdown cycle uses flash tanks and heat exchangers that promote the maintenance of water and heat levels. Lost heat can be recovered through this process easily. The high temperature and water contents create a condition for corrosion to occur; the presence of the solid impurities accelerates the formation of acids and alkalis, which work on the surface of the boiler.
However, the setting of the continuous blowdown depends on:
- The design of the boiler
- The feed water properties
- Operating conditions of the boiler
Control of the blowdown process is essential to preventing explosions and other problems caused by flash steam and pressure differences.