235 MW DIESEL PLANT AIDS WITH PHILIPPINE NEEDS
By Alvin C. Kintanar
Bauang Private Power Corp.
Answering the call of the Philippines government in addressing the crippling power crisis of the early 1990s, the Manila Electric Co., First Philippines Holdings Corp., JG Summit Holdings Corp. and PCI Capital pooled their resources to incorporate the First Private Power Corp. (FPPC) and build a $200 million, 235 MW diesel power plant in Bauang La Union.
The build-operate-transfer (BOT) between the National Power Corp. (NAPOCOR), the entity representing the Philippine government, and FPPC was signed on Jan. 11, 1993, as a result of the bidding conducted by NAPOCOR on this fast-track project. FPPC incorporated the Bauang Private Power Corp. to undertake the project and operate and maintain the facility after completion. FPPC decided to use the skills of the Filipino and went into a semi-turnkey arrangement in the execution of the project.
Located 255 km north of Manila, on a 22-hectare coastal land along the Lingayen Gulf, the power station consists of 21 units with Sulzer 16ZA40S diesel engines burning poor-quality heavy fuel oil. Three power buildings, called sectors, each house seven diesel generator sets. Each set rotates at 514 rpm, has 16 cylinders in a V-form arrangement and is capable of delivering 11.52 MW at the flywheel. Each is configured as a unit system, meaning that each unit has its own lubricating oil system, fuel oil change-over and viscosity control system, charge air system, starting system, high/low cooling water system, lubricating oil treatment system, electrical system and control system. Common to each sector are the air compressors supplying both the control and service requirements; auxiliary transformer, a step-down transformer with a primary voltage of 13.8 kV and a secondary of 480 V; fresh make-up and dirty lubricating oil tanks; and 480 V distribution system, 13.8 kV medium-voltage switchgear and a sector control room.
Bunker fuel is delivered through a 1.6 km submarine pipeline to two 100,000 bbl steel storage tanks. At maximum output, these storage tanks are capable of supplying the 30-day requirements of the power station. The fuel is then transferred to two 1,000 m3 settling tanks. The fuel then passes through centrifuges for cleaning before it is stored in three 250 m3 separate day tanks that supply each of the sectors. Cold start-up of the diesel generator sets is accomplished via a light fuel oil stored in two 250 m3 oil tanks.
Lubricating and fuel oil sludge are passed to an API separator to separate the water from the oil constituents. The sludge is stored in 250 m3 and 2,300 m3 tanks. The separated water is further treated in a cavitation air flotation unit before it is discharged into a lagoon. Usual oil content of discharge is less than 3 ppm, which is way below the 10 ppm limit set by the Department of Environment and Natural Resources.
Fuel is heated by steam generated by heat recovery boilers mounted on diesel generator exhaust silencers. Each sector has three exhaust recovery boilers.
Generator voltage is at 13,800 V. Each generator is connected to the 13,800 V bus bar through an SF6 circuit breaker. Total output of the sector is fed to a 100 MVA step-up transformer with a primary voltage of 13.8 kV and secondary of 230 kV.
A ring-bus substation is arranged for the safe interconnection to the NAPOCOR grid. A 375 kVA blackstart diesel generator set is also provided.
Control of the facility is accomplished through three levels. A direct engine level of control is available, while in each sector a local control room is provided. Here, on a per-engine basis, each diesel generator set and its associated auxiliaries can be monitored and controlled. The highest level of control is the distributed control system (DCS) which can be accomplished at the main control room located at the middle sector. The DCS is capable of monitoring and controlling the whole power station from the main control room.
During the 15-year BOT the annual guaranteed energy is 1,700 GWh based on the contracted capacity of 215 MW. The average capacity factor since commercial operation is 63 percent, with an average availability of 95 percent. Average net plant heat rate is 8,289 Btu/kWh based on LHV of 17,430 Btu/lb and station service load of 4.5 percent.