The catastrophic failure of the main blower of a the main blower of a petrochemical plant boiler

RhidiyanWaroko

08063319350806331935

Program StudiTeknik Material

Outline

� Analyze incident report

� Identify common failure� Identify common failure

� Identify common root cause

� Identify common manifestation

Analyze incident reportSystem description

� Power of blower 500 HP, by steam turbine at 5512 rpm through a gear box

� Has a rotational speed controller and a centrifugal over speed monitoringsystem (trip valve)system (trip valve)

Event chronology

• The event took place shortly after manually latching the trip valve to resetautomatic speed control.

• The rotor of blower was destroyed and parts of rotor caused severe damageto the blower housing and adjacent facilities.

• The leading edge of a blade was punched a water wall tube.

Identify common failure

Initial incident

IncidentCatastrophic failure at

petrochemical plant boiler

Blower PipingSignalling and control system

Steam turbine and lubrication

Suspect part

Initial incident Blower

Gear box Rotor shaft Rotor/ Blade

PipingSignalling and control system

and lubrication system

a. Housing b. Rotor shaftc. Gear box shaft d. Couplinge. Back plate f. Cone

Sequence of the failure:Breakage of one or more blade �

unbalanced force � Displacement coupling� deformation of rotor shaft and gearboxshaft � blade torn away and caused damageto the near facilities.

Identify common root cause

Failure Blower

Cause

Cause

Cause Blade

Operational conditions

Over speed Over heat

Design and material

Maintenance

Cause

Cause Over speed

Controlling system

Trip valve Operator

Over heat

Identify common root cause (2)

� Two over speed events took place previously tothe failure.the failure.

� Extrapolation evidences that the turbine mighthave reached a speed of the order of 1823 rpm.(1500 rpm)

� This over speed represents a 28% increase overthe rated speed and an increase of 63% inthe rated speed and an increase of 63% incentripetal acceleration.

� Consequently stresses suffered by the materialof the rotor also increase by 63%.

Identify common root cause (3)

Final failure event: Catastrophic failure, breakage of one or more blade

Breakage blade due to impact. Impact was found due to unbalanced forced at that system

Unbalanced forced at the system is cause by overspeed of rotor

There is a system to control rotational speedThere is a system to control rotational speed

Rotational speed controller was error

Identify Common Manifestation

� Checking a rotational speed controlsystemsystem

� Full stress analysis will be performed toasses proper safety factors and maximumallowable over speed.

THANK YOU