Soot Blowers

Soot blowers are becoming less and less important in the Petrochemical and Refinery industry during modern times. The reason for this is that generally, any component of the flue gases that can foul the tubes can also foul the air. So, as clean air requirements continue to get more stringent, the resulting cleaner fuels are less likely to foul the tubes. However, since many areas of the world continue to burn fuel oils that are likely to require soot blowing, the following guidelines are presented to demonstrate their application.

Soot blowers as used in these furnaces are usually one of the following types:

The retractable blower gets it's name from the fact that the element that does the cleaning is retracted out of the hot gas stream when it is not in use. Since it has less nozzles than a fixed rotary blower, it can produce a better cleaning velocity for the same steam pressure. This type blower is used for the higher temperature and dirtier fuel applications.

The rotary blower is in a fixed position and since the element is supported by the hangers at different points, the element requires less material than the retractable blower. This blower costs less than the retractable, but requires a greater volume of steam. This type blower is used for the lower temperature and cleaner fuel applications.

Oil - ash corrosion becomes more severe with increased temperatures and the nature of the corrosive agent. Above 1300°F where V₂O₅ or other mixtures sinter and melt, corrosion is intensified. The significant part that sodium plays in forming low melting complex compounds indicates that not only vanadium, but also sodium is highly undesirable in residual fuel oil as it affects fire side deposits.

Under normal operating conditions, we recommend sootblower selection as follows:

Under control conditions other factors may be used to modify sootblower selection.

Down to a ratio of 20/1 the corrosion rate is not much affected at constant temperature.

Below this point corrosion rates will be reduced even to a low figure at the theoretically correct ratio.

The lower corrosion at the lower ratios is explained by the formation of V₂O₃ or V₂O₄ rather than V₂O₅. These lower oxides of vanadium have a higher melting points than V₂O₅ and tend to be carried through the system as harmless dust.

The following tables may be used to estimate the effective cleaning radii.

Fuel : Cleaning radius based on use of # 6 Fuel Oil.

Gas temperatures dictate element materials as listed below:

Up to 900 °F - Carbon Steel

900 °F to 1500 °F - Chrome Alloy

1500 °F to 1800 °F - Hi Alloy

Fuel : Cleaning radius based on use of # 6 Fuel Oil.