PVUThe MAN developed ME-GI pump vaporizer unit (PVU) is a standardized compact, high quality pump unit for supply of LNG to MAN B&W two-stroke ME-GI engines. The pump unit includes pump, vaporizer, filters and a control system with safety functions and a high degree of integration with the MAN B&W ME-GI engine.  

Working principle

The PVU is designed to pressurize and vaporize the LNG to the pressure and temperature required by the MAN B&W two-stroke ME-GI engine. The PVU receives subcooled LNG supplied by a cryogenic centrifugal pump and the LNG is pressurized by a high pressure reciprocating pump, consisting of three cylinders actuated by linear hydraulic pistons. The pressurized LNG flows through a compact printed circuit heat exchanger, where it is heated by warm glycol water. Fine particles present in the gas are caught by the high pressure filter, before the gas is directed towards the gas valve train (GVT) and the engine. The gas pressure is controlled by control of hydraulic flow to the pump. The separate control of the three pump heads provides 100% redundancy.    

Benefits

With a compact and intelligent design, the PVU introduces a considerable saving in the complete low flashpoint fuel supply system (LFSS). This is because of the simplifications implemented in the design, resulting in a reduced number of sub-systems and components and due to the cryogenic pumps being actuated individually, enabling embedded redundancy. This means that one pump cylinder can be taken out of service for overhaul, while the remaining two are fully operational, and can supply 100% of the required capacity. In comparison, traditional crankshaft driven pumps require two complete units to allow system redundancy. By choosing hydraulic supply for the PVU from the ME-engine HPS, the installation cost is further reduced significantly.  

The PVU control system is designed based on knowledge of the ME-GI engine and the PVU mechanics. This ensures dedicated control integration between the systems, and high gas supply control accuracy and condition monitoring features. The engine gas pressure and flow demands are quickly transferred to the PVU, resulting in a stable gas pressure control, in which it secures efficient ramp up and ramp down in all operating conditions. Further, the GVT downstream of the PVU is controlled by the ME-GI engine control system, ensuring integrated control with the ME-GI engine. The PVU control system is based on the same hardware platform as the ME engine control system, which means that no extra spare parts are required.

Scope of supply
  • Hydraulic driven cold-end pumps – 3 pieces
  • Compact vaporizer heated by glycol water
  • Cold-return line for continued circulation (no suction drum needed)
  • Blow-off valve and safety valves
  • Electrical cabinet with 3 x MPC
  • Hydraulic power supply (optional)
  • Sensors for control and supervision
  • Pump strainer (standard 160my)
  • NG filter after vaporizer (10my)
  • Filter for glycol water (250my)
  • Fully automated
  • PVU control system including supervision of operational conditions
  • Class approval certificate for PVU (Hazop/FMEA submission to class societies)
  • Installation and operation manuals via MDT documentation system
  • List of capacities etc.
ME-GI Pump Vaporizer Unit_Illu.pdf - Adobe Reader