The main cargo pump system consists of three vertical centrifugal single stage double suction type cargo pumps. They are situated at the bottom of the pump room and are driven by a single stage Curtis steam turbine and intermediate shaft passing into the pump room through a gas tight bulkhead gland. The pumps are each equipped with an automatic unloading (stripping) system (AUS).
Procedure for the Operation of Cargo Pumps
a) The chief officer/duty deck officer should notify the duty engineer of cargo pump requirements, giving at least one hours notice. The duty engineer will then make the cargo oil pumps ready for operation.
b) Before the cargo pumps are run up the duty cargo officer is to:
• Ensure the pump discharge valves are closed
• Ensure the pump volute casing and separator chamber are primed
• The pump and line suction valves are fully open
The operation for bringing the cargo oil pump turbines up to minimum speed is carried out at the turbine side by the duty engineer. Only after this point will command of the pumps be passed over to the chief officer/duty deck officer in the CCR. Initially the steam lines to the turbines are drained of any water and the casing warmed through. After this period, each turbine is spun at approximately 100 to 200 rpm for approximately 25 minutes, when this period has elapsed and no faults found, each pump will be tripped. After the trips have been reset, the turbines are run up to the minimum speed setting where the governor will take over control of the speed. This period will take approximately 15 to 20 minutes. If all is satisfactory, the duty engineer will then inform the chief officer/duty deck officer that control can now be carried out from the CCR.
Note: The warming up period at low revolutions is kept to a minimum, sufficient to ensure that condensate is expelled before the pump speed is increased. Extended operation at low revolutions could lead to overheating of the final stages of the turbine and local uneven heating of the casing.
a) During the warming up period if the pump discharge pressure rises above 0.5MPa open the pump discharge valve gradually to limit the pressure increase.
The duty engineer will check that there is no abnormal noise or vibration in the turbine and the reduction gear. If an abnormal state is noticed, the turbine will be stopped immediately and the problem investigated.
b) The duty engineer will trip the turbine(s) by operating the hand trip knob to confirm that the governor control valve closes immediately. The trip will then be reset. Ensure that the pump discharge valve is shut before the pump is run up again.
c) The pump discharge valve should be shut before the duty deck officer tests the emergency trip mechanism of each pump on the cargo console in the CCR or at one of the outstation trip positions. The duty engineer will reset the trip when the turbine is fully stopped and the speed setting is at minimum. The pump(s) will then be restarted as required.
a) Inform the duty engineer that a COP is about to be stopped then decrease the turbine speed gradually down to minimum speed.
b) Stopping is possible by operating either a remote emergency stop at one of four outstation positions, the individual cargo oil pump turbine STOP button on the CCR cargo console or at the pump room bottom plates level or the hand trip on the turbine. The pump discharge valve should be shut before the pump turbine is stopped.
c) Close the pump suction valves.
Pull the hand trip knob so that the spindle moves outward and the governor valve closes through activation of the trip mechanism causing the turbine to stop.
Press the remote stop buttons provided at the remote stop stations so that the trip mechanism activates to close the governor valve and stop the turbine, the remote stops are located at the following locations:
• Outside of the pump room entrance, port and starboard sides
• Pump room bottom plates
• Midship manifolds after end, port and starboard
• CCR cargo console
Resetting the Emergency Trip
Before resetting the emergency trip, ensure the following conditions are fulfilled:
• The pump is at the minimum load, i.e. the pump discharge valve is fully closed.
• The governor speed setting is at the minimum speed.
• The turbine steam inlet valve is fully closed and the turbine is stopped.