MMA Assessment OICEW-5-1F

Start fresh water generator

Condition

Using an approved simulator, in the laboratory, or aboard ship and given access to a steam heated flash-type, jacket water heated Nyrex-type or a reverse osmosis fresh water generator as selected by the assessor.

Performance requirement

Behavior Standard
The student will: During assessment, the student shall, at a minimum:

Identify the valves and pumps associated with the freshwater generator selected by the assessor

identify:

  • all associated pumps
  • valves required for startup

Start the selected freshwater generator

follow the ship specific evaporator starting procedure provided during training

Line up the discharge to meet operational requirements

Before proceeding:

  • check that selected tank is not full
  • state salinity limits for tank selected
  • check that discharge salinity is within limits

Operate the freshwater generator until operations stabilize

Check, as appropriate:

  • discharge salinity
  • shell vacuum
  • feed temperature
  • liquid levels
  • pump operations
  • chemical feed

Location

Assessed in EN‑4231 Sea Term IV: Marine Engineering.

References

STCW Knowledge, Understanding and Proficiency

  1. OICEW-A4.1
  2. OICEW-A4.3

NVIC Tasks

  1. NVIC 17-14 Task 4.3.N Start fresh water generator
  2. NVIC 17-14 Task 4.3.P Start fresh water distiller
  3. NVIC 17-14 Task 4.3.W Start and secure a reverse osmosis plant

Check that the following valves are open:

  • Brine pump overboard
  • Chemical feed pump discharge
  • Feed heater attemporator supply
  • Sea water heater vent to drain regulator
  • Sea water heater drain to bilge
  • Air ejector condensers drain to bilge
  • Distillate pump sealing line
  • Distillate pump discharge valve
  • Distillate discharge to distribution manifold
  • Inlet valve to reserve feed or potable tank
  • Sea water suction valve to sea water supply

Check that the following valves are closed:

  • Air ejector condenser drain to ADT
  • Sea water feed heater drain to auxiliary condenser
  • Sea water feed regulating valves to 1st effect/Brine pump discharge

Start:

  • Sea water feed pump and throttle inlet to 1st effect
  • Chemical feed pump (insure proper level in tank)
  • Brine pump and maintain level in 2nd effect hotwell

Open:

  • Steam supply to air ejectors
  • Steam supply to feed heaters (auxiliary exhaust or L.P. bleed)
  • Feed heat attemporator root valve from condensate system

Turn on:

Salinity panel (insure 3 way dump valve is tripped to bilge)

Monitor:

  • Feed heater shell temperature between 185-205° F.
  • Sea water feed temperature between 165-170° F.

Start:

Distillate pump, and regulate level by throttling discharge valve

Line up:

  • 3-way trip valve to proper tanks when salinity is less than .25 gpg
  • Secure air ejector condenser drain to bilge and direct drains to ADT
  • Secure sea water feed heater drain to bilge and direct drains to the auxiliary condenser

Reverse-osmosis start-up procedure

  1. Make a cursory examination of the plant to ensure that the system is intact, that all components are fully assembled, and that the unit is in a state of operational readiness.
  2. Ensure that all pre-filter, media filter and cartridge filter drain and vent valves are closed.
  3. Opens all sea water valves from the sea chest up to the unit, the sea water inlet cock valve, and the feed water pump isolation valves if the unit is so equipped.
  4. Position the 3-way feed/rinse/clean/store valve to the normal feed position and lines up the media filter isolation, back-flush, and waste outlet valve for normal operation.
  5. Position the 3-way media filter outlet valve to the normal feed position to the cartridge pre-filters.
  6. Open the back pressure regulator bypass valve fully and completely backs off on the back pressure regulator valve.
  7. Position the 3-way brine discharge/rinse/clean/store valve to the normal overboard position and ensures that all the brine discharge valves to the overboard skin valve are all open.
  8. Ensure that electrical power is established to the unit by closing the appropriate circuit breaker.
  9. Checs oil level in high pressure pump crankcase, and add oil as necessary.
  10. Place the feed pump and feed booster pump switches in the automatic mode as appropriate if so equipped.
  11. Depresse the unit salinity controller start switch, observe feed pump, booster feed pump, and high pressure pump pressures and feed flow meter, bleeds air from pre-filter, media filter, and cartridge pre-filters as needed, and checks for system leaks.
  12. Once proper feed has been established, slowly close the back pressure regulator bypass valve, and close in on back pressure regulator until manufacturer recommended design pressure is reached for the existing sea water salinity. Observe the fresh water product flow meter.
  13. Line up the fresh water system valves to permit delivery of fresh water to the fresh water storage tank on service and monitor the salinity of the fresh water product.
  14. Ensure that an acceptable salinity is eventually reached on fresh water product and that the 3-way fresh water product diverting valve switches from the overboard discharge to the fresh water delivery mode
  15. Monitors system, pressures, flows, and salinity to ensure that parameters remain within acceptable limits.

Reverse-osmosis shut-down procedure

  1. Depress the unit salinity controller stop switch and ensures that the feed pump, booster feed pump, and high pressure pump all stop rotating and that their respective indicator lights go out.
  2. Close all sea water valves from the sea chest up to the unit, the sea water inlet cock valve, and the feed water pump isolation valves if the unit is so equipped.
  3. Open any valves in the cleaning tank discharge line to the unit 3-way feed feed/rinse/clean/store valve.
  4. Position the 3-way feed/rinse/clean/store valve to the rinse position and line up the media filter isolation, back-flush, and waste outlet valve for normal operation.
  5. Ensure that multi-media filter and cartridge pre-filter drain valves are closed.
  6. Open the back pressure regulator bypass valve, and backs off on the back pressure regulator valve fully to release the pressure from the unit.
  7. Ensure that the 3-way brine/clean/store/rinse valve is in the normal brine discharge position.
  8. Fill the cleaning tank with chlorine free product fresh water.
  9. Place the booster pump control switch to the “hand” position and observes the feed flow meter.
  10. When the feed flow meter indicates no flow (and the cleaning tank is now empty and

Nyrex start-up procedure

  1. Open valves on the suction and discharge side of the ejector pump.
  2. Open overboard valve for combined brine/air ejector.
  3. Close vacuum relief valve which is on top of the Nirex shell.
  4. Start ejector pump to create a vacuum.
  5. Check that no water is visible in sight glass on separator. Continue when the vacuum reaches at least 90%.
  6. Open steam to heater if not on jacket water.
  7. Open the hot water inlet and outlet valves.
  8. Start the hot water supply to distiller by adjusting the bypass valve until the desired jacket water temperature is reached. The boiling temperature now rises, while the vacuum drops to approximately 85%. Water flow can be seen in the air suction sight glass. This indicates that evaporation has started.
  9. Open the valve to freshwater tank.
  10. Switch on the salinometer.
  11. Start the freshwater pump.

Nyrex shut down procedure

  1. Secure the steam supply to the plate heat exchanger.
  2. Let hot water pump run for about five minutes, then secure.
  3. Stop the freshwater pump.
  4. Switch off salinometer.
  5. Stop the ejector pump.
  6. Open vacuum relief valve on the separator shell.
  7. Close inlet and outlet valves for ejector pump.
  8. Close outlet valve for combined brine/air ejector.

See the Assessment Guidelines for additional specifications of behavior and standards.