Cargo Operated Pump Turbine- Starting, stopping

Cargo operated pump turbine (COPT) is required on tanker ships for discharging of loaded cargo to the port.

COPT is steam driven centrifugal pump operated by steam produced from the ship’s boiler.

STARTING

Check the lube oil sump level Start the lube oil priming pump and check the pressure Operate the vacuum condenser seawater pump suction and discharge valves to obtain a flow through the condenser Switch on the breaker for vacuum condenser pump Start the pump and check sea water pressure Open the lube oil cooler seawater valves Check the level for vacuum pump water supply Check the water level in the condenser Operate drain valve of turbine casing and remove the water Operate the steam inlet and exhaust valves opening gland Steam valve to provide sufficient steam pressure to the gland Start the vacuum pump and check the vacuum pressure Operate the condensate pump suction and discharge valves and then start the pump Press the turbine rolling button and start warming up the COPT and check all the parameters Check if the steam drain valve is open After warming up, turbine will be ready to start Check auxiliary boiler steam pressure when COPT is in operation

“The pump casing vent line should be used to verify that the pump is filled with cargo before it is started.”

STOPPING

Reduce the boiler load as per the consumption of steam When the COPT is stopped, steam consumption is reduced, so adjust the load on boiler accordingly After stopping the stripping pump, put the boiler on minimum firing load Shut the steam inlet valve to stripping pump Reduce the dump valve setting so that the steam pressure can be reduced Stop the boiler and changeover to 6-9 bar mode Shut the main dumping valve by putting the setting to zero Shut the main steam valve for the COPTs Shut the gland steam valves and air ejector steam inlet and outlet valves Put the vacuum condenser condensate pump in manual and stop it, and shut the inlet and outlet valves of the condensate pump Open the drains of all the COPTs, and drain the water. Close the drains after draining the water Let the vacuum condenser cooling sea water pump running for 1 hour for cooling Stop the vacuum condenser cooling sea water pump after 1 hour and shut the inlet and outlet valves of the pump Stop the lube oil priming pump

“Means shall be provided for stopping the cargo pumps at the manifolds and at the lower pump room level.”

Preparing COPT for Cargo Operation

Change the boiler to high firing mode Start the COPT as discussed above Ensure to adjust the gland steam pressure and maintain it in between 0.3 –0.5 KG/cm2 Ensure COPT condenser vacuum is at correct pressure Blow off the manual drain line for COPT steam line and governor drains Open manual inlet valve for selected IG blower Open measuring line from the selected blower to the O2 analyzer and ensure other lines are kept shut Ensure the four position cock on the analyzer control panel is on the sample side Start the IG system IG mode must be selected at least 20 minutes before the cargo discharge operation Ensure boiler ramps up to 40% load and O2 analyzer reading for the gas delivered in below 5% Confirm with chief officer that transfer of COPT control to duty deck officer can be done Transfer the COPT controls from remote to local i.e. to cargo control room

References

The Ultimate Guide to Operating Procedures of Engine Room Machinery. Anish Wankhede [2014]