Fan Applications in the Cement & Lime Industry Fan Selection Basics Visit CB Power and Industrial Equipment for more information: www.cbpowerandindustrial.com

Fan Selection Basics

Visit CB Power and Industrial Equipment for more information:

www.cbpowerandindustrial.com

Fan Selection Basics POINT OF OPERATION DENSITY EFFECTS SYSTEM EFFECT FACTORS KEY FAN PERFORMANCE DEFINITIONS AGENDA

POINT OF OPERATION

DENSITY EFFECTS

SYSTEM EFFECT FACTORS

KEY FAN PERFORMANCE DEFINITIONS

Point of Operation System Resistance Higher than Estimated Lower resistance, but higher power Safety Factor

Density Effects Temperature Elevation Suction Pressure (absolute)‏ Moisture content Molecular weight System resistance varies approximately with gas density at the operating point. Variables are: Density = 0.075 x (70 + 460) / (600 + 460) = 0.0375 lb / C.F. (at 600°F)‏ Density = 0.075 x elevation factor Density = 0.075 x (407 + (-30)) / (407) = 0.0695 lb / C.F. (-30” WG at inlet)‏ Density from psychometric chart Density = 0.075 x 44 / 29 = 0.1126 lb / C.F. (CO 2 / Air)‏

Temperature

Elevation

Suction Pressure (absolute)‏

Moisture content

Molecular weight

Density Effects Fan is a constant volume device Most processes are based on mass flow rates Incorrect density results in a volume rate which can be too low, and therefore the fan will be sized too small! Why is density so important?

Fan is a constant volume device

Most processes are based on mass flow rates

Incorrect density results in a volume rate which can be too low, and therefore the fan will be sized too small!

Density Effects Example 225,000 lb/hr (3750 lb/min) combustion air required @Density = 0.075 lb/C.F., Volume = 50,000 cfm @Density = 0.050 lb/C.F., Volume = 75,000 cfm A larger fan is required to meet the second volume flow rate!

What are System Effects? Result from non-uniform inlet flow into fan or other system components. Is a function of component spacing. Actual loss through fitting/component is higher than anticipated Often not considered by system designers! System Effects

What are System Effects?

Result from non-uniform inlet flow into fan or other system components.

Is a function of component spacing.

Actual loss through fitting/component is higher than anticipated

Often not considered by system designers!

System Effects

System Effects

System Effects

Inlet Conditions: elbows too close to fan inlet inlet spin due to duct design abrupt duct transition dampers not fully open damper locations poorly designed guards inlet too close to walls or bulkhead Outlet conditions elbows too close to fan outlet free discharge discharge too close to wall or bulkhead abrupt transitions damper location weatherhoods discharge guards System Effects

Inlet Conditions:

elbows too close to fan inlet

inlet spin due to duct design

abrupt duct transition

dampers not fully open

damper locations

poorly designed guards

inlet too close to walls or bulkhead

Outlet conditions

elbows too close to fan outlet

free discharge

discharge too close to wall or bulkhead

abrupt transitions

damper location

weatherhoods

discharge guards

System Effects

Fan Performance Definitions TP = SP + VP Total Pressure = Static Pressure + Velocity Pressure Fan Static Pressure (FSP) FSP = SP outlet - TP inlet Static Pressure Rise (SPR) SPR = SP outlet - SP inlet

TP = SP + VP Total Pressure = Static Pressure + Velocity Pressure

Fan Static Pressure (FSP) FSP = SP outlet - TP inlet

Static Pressure Rise (SPR) SPR = SP outlet - SP inlet