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:

Retractable Soot Blower:
Retractable 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.
Fixed Rotary Soot Blower:
Rotary 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.
Fuel Oils:

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.

Sootblower Recommendations:

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

A. Below 100 ppm vanadium or 25 ppm sodium or 2% sulphur in the fuel oil:
Rotary sootblower to 1800°F gas temperature.
Retractable sootblower above 1800°F.
B. 100 to 200 ppm vanadium or 25 ppm sodium or 2% sulphur in the fuel oil:
Rotary sootblower to 1300°F gas temperature.
Retractable sootblower above 1300°F.
C. Above 200 ppm vanadium or contents in excess of 25 ppm sodium or 2% sulphur in the fuel oil:
Rotary sootblower to 1050°F gas temperature.
Retractable sootblower above 1050°F.

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

Air/Fuel Ratio:

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.

Rotary Sootblower:

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

Maximum Element Length of 10', Normal Tube Size Up To 3 1/2"
Tube Arrg'tStudsFinsSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Up to 3/4" 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
Over 3/4" 4'-0" 2'-0" 2'-0" 2'-0" 4'-0" 2'-6"
3/inch 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
5 to 7/inch 4'-0" 2'-0" 2'-0" 2'-0" 4'-0" 2'-6"
Triangular Up to 3/4" 4'-0" 2'-0" 2'-0" 2'-0" 4'-0" 2'-6"
Over 3/4" 3'-0" 1'-6" 1'-6" 1'-6" 3'-0" 2'-0"
3/inch 4'-0" 2'-0" 2'-0" 2'-0" 4'-0" 2'-6"
5 to 7/inch 3'-0" 1'-6" 1'-6" 1'-6" 3'-0" 2'-0"
Maximum Element Length of 20', Normal Tube Size Up To 4" And Over
Tube Arrg'tStudsFinsSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Up to 3/4" 6'-0" 3'-0" 3'-0" 3'-0" 6'-0" 3'-6"
Over 3/4" 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
3/inch 6'-0" 3'-0" 3'-0" 3'-0" 6'-0" 3'-6"
5 to 7/inch 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
Triangular Up to 3/4" 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
Over 3/4" 5'-0" 2'-6" 2'-6" 2'-6" 4'-0" 2'-6"
3/inch 5'-0" 2'-6" 2'-6" 2'-6" 5'-0" 3'-0"
5 to 7/inch 4'-0" 2'-0" 2'-0" 2'-0" 4'-0" 2'-6"
Maximum Element Length of 10', Normal Tube Size Up To 3 1/2"
Tube Arrg'tSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Bare Tubes 10' 5' 5' 4' 9' 5'
Triangular Bare Tubes 8' 4' 4' 3' 7' 4'
Maximum Element Length of 20', Normal Tube Size Up To 4" And Over
Tube Arrg'tSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Bare Tubes 12' 6' 6' 4' 9' 5'
Triangular Bare Tubes 10' 5' 5' 4' 9' 5'
Retractable Sootblower:

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

Normal Tube Size Up To 3 1/2"
Tube Arrg'tStudsFinsSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Up to 3/4" 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
Over 3/4" 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"
3/inch 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
5 to 7/inch 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"
Triangular Up to 3/4" 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"
Over 3/4" 5'-0" 2'-6" 2'-6" 2'-6" 5'-6" 3'-0"
3/inch 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"
5 to 7/inch 5'-0" 2'-6" 2'-6" 2'-6" 5'-6" 3'-0"
Normal Tube Size Up To 4" And Over
Tube Arrg'tStudsFinsSootblower Spacing(See Figure 1 to 4)
A B C D E F
Square Up to 3/4" 8'-0" 4'-0" 4'-0" 4'-0" 8'-6" 4'-6"
Over 3/4" 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
3/inch 8'-0" 4'-0" 4'-0" 4'-0" 8'-6" 4'-6"
5 to 7/inch 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
Triangular Up to 3/4" 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
Over 3/4" 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"
3/inch 7'-0" 3'-6" 3'-6" 3'-6" 7'-6" 4'-0"
5 to 7/inch 6'-0" 3'-0" 3'-0" 3'-0" 6'-6" 3'-6"

Figure 1 : Square Pitch Finned Tubes : Longitudinal Arrangement
Square Pitch/Longitudinal


Figure 2 : Triangular Pitch Finned Tubes : Longitudinal Arrangement
Triangular Pitch/Longitudinal


Figure 3 : Square Pitch Finned Tubes : Perpendicular Arrangement
Square Pitch/Perpendicular


Figure 4 : Triangular Pitch Finned Tubes : Perpendicular Arrangement
Triangular Pitch/Perpendicular


Recommended Minimum Blowing Pressures
Rotary Sootblower
Element length up to 10' maximum, tube sizes up to 3 1/2" OD
Square Pitch150 psig
Triangular Pitch200 psig
Rotary Sootblower
Element length up to 10' up to 20' maximum, tube sizes 4" OD and over
Square Pitch175 psig
Triangular Pitch225 psig
Retractable Sootblower
Square Pitch100 psig
Triangular Pitch150 psig