1.1 Project brief
This power plant is designed as continuous main electrical source in Pakistan.
The power plant consists of 1 set of diesel generator, with capacity of 2000KW per set.
1.2 DG set configuration
The specification outlines the scope of supply for each DG set;
The DG set is driven by diesel engine model GN8320ZD8 manufactured by Nb Power ry Group Co., Ltd., which is the largest middle speed engine manufacturer in China;
The engine will use diesel oil/heavy fuel oil as fuel. The fuel treatment equipments are designed according to the requirements of using heavy fuel oil.
1.3 Standard & code
The design is according to the Chinese standard & code, in line with ISO/IEC standard. The project is designed under the merit of "advanced technology, highly efficiency, safety, economy and practicality".
The installation and the commissioning should be in line with the above standard & code.
1.4 Project scope
The scope of the Seller:
Engineering design of the power plant, including power system, fuel system, lubricating oil system, starting air system, cooling water system, air intake & exhaust, compressed air system, control & measuring system, electrical system, etc;
Supplying equipments and materials according to the scope of delivery list;
Installation guide and commissioning of the power plant;
Operation training
1.5 Design Fundamentals
2.1 Civil work:
The civil works of the power station are NOT in Supply Scope. The Seller will provide the following drawings and technical information, which will assist civil consultant in designing the foundation and powerhouse.
- General assembly drawing
- Powerhouse layout
- Foundation plan.
- Schematic piping diagram.
The Buyer shall provide the following data for information and use:
. Soil bearing capacity
. Dynamic characteristics of soil
2.2 Soft water:
Water for exhaust boiler shall be softened according to the international standard and the Chinese standard (GB). Water for DG need not to be softened.
2.3 Fuel:
HFO (Heavy Fuel Oil) and diesel oil are the main fuel. The HFO need to be treated before entering the generating sets. The fuel treatment equipments for this power plant are designed according to heavy fuel oil.
2.4 Cooling water:
Adopt open cooling tower system.
2.5 Electricity:
The generator will supply 400V electricity.
3. General arrangement:
3.1 Main building
The main building will be arranged in 2 lines:
The first line (Control room) is for the electrical control room, switchgear room, water soften treatment room and air compressor, air receiver. The second floor is for steam exhaust gas boilers and silencers, boiler is hypaethral layout. The distance of the columniation is 6 m; the span is 8 m, length is 18M and height is 4 m;
The second line (Generator hall) is for DG, lube oil tank, booster, etc, the span is 18m, length is 18m; there is a traveling double girder crane (10t) in the room.
a. Control room
The total area of control room is 144 square meters with length of 18m, width of 8m and height of 4 m. The roof of the control room is of reinforced concrete construction, and is flat roof that is convenient for installing equipments on it. One silencer and its bracket with weight of 0.8 ton are arranged for each generator. An exhaust gas boiler with weight of 5 tons is arranged for generator, total is 2 boilers.
All cables will be connected to switchgears or control panels through cable channels in the control room.
Double deck sound insulation glazing with length of 1800 mm, width of 1500 mm, and thickness of 8 mm is installed on the control room wall facing to the alternator end of the generator. The bottom of glazing shall be 800 mm above the ground.
Ventilation for the control room adopts air conditioner.
b. Generator hall
The total area of steel construction main building is 324 square meters with length of 18 m, width of 18m. The distance of the columniation is 6 m. A 10 tons double girder bridge crane with span of 16.5 m is installed in the generator hall. The installing height of columniation for crane railway is 7 m, and its total height is 9.6m. The maximum height of the main building is 12.8 m.
Main equipments in generator hall:
a. 1 set of 2MW generator
Model: 2000GF1-2; Rated power: 2000kW; Rated speed: 600r/min; Weight for each generator: 44 tons including diesel engine 25 tons, alternator 16 tons and engine frame base 2.8 tons.
b. One set of fuel booster module
Weight for the fuel booster module: 2 tons
c. One set of HFO separator module
Weight for separator module: 2000kg
3.2 Water pond
One water pond is arranged besides the main building. The water pond is of reinforced concrete construction with length of 4 m, width of 4 m, and height of 3 m. The wall thickness of the water pond is 0.3 m.
One cooling tower is installed on the water pond.
Cooling tower specifications:
Model: GBL-100; Fan diameter: 1800mm, Fan motor: 5kW, Dry weight: 1800kg, Wet weight: 2000kg.
4. System specifications:
4.1. Diesel generating set:
According to the power capacity 2MW, the project plan configures 1 unit of diesel generator.
Rating of the D.G. set
Under above mentioned site conditions
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Rating at Alternator Rating at
engine efficiency alternator
crankshaft terminal(MCR)
KWm ( % ) KWe KVA(0.8 pf)
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Nominal 2206 94.5 2000 2500
Running
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Note: COP rating will be 90 % of MCR
4.1.1. 2MW diesel engine:
Technical particulars for the diesel engine are as follows:
Number of cylinders 8
Arrangement of cylinders In Line
Bore (mm) X Stroke (mm) 320 X 380
Type 4-stroke, direct injection, turbocharger, after cooler
Rotational speed 600 RPM
Mean effective pressure 18 Bar
at rated power & speed
Mean piston speed 7.6 m/sec.
Rotation seen from flywheel Clockwise.
Swept volume per cylinder 30.578 litres
Combustion chamber volume 2.352 litres
Compression ratio 13:1
Max. combustion pressure 125 bar
(at rated power/speed)
Power rating
Rated power under ISO Conditions
Maximum continuous rating (MCR) 3000 HP
at engine crankshaft
Corresponding rotational speed 600 RPM
Under the following limiting ambient conditions:
Air temp. at turbocharger inlet 45 deg. C
Water temp. at charge air cooler inlet 32 deg. C
Dearation to power applicable for engine 0 %(nil)
Beyond the abovementioned limiting conditions, deration to power as per ISO 3046 will be applicable.
Rated Power under site conditions mentioned above:
Maximum continuous rating (MCR) 3000 HP
at engine crankshaft
The engine should be capable of accepting a sudden load as per the guidelines in ISO-8528-5-1993(e). As per this standard, the maximum sudden load increase stages are
Baseload % Sudden load increase to %
--------------------------------------------------------------------------------
1st Stage 0% 40 40%
2nd Stage 40% 30 70%
3rd Stage 70% 20 90%
4th Stage 90% 10 100%
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During each of the above-mentioned stages of sudden loading, the transient speed drop will be restricted to a maximum value of 10% of the rated speed.
4.1.2 Alternator
The Alternator is self-excited, brush-less type in two bearing construction with single shaft extension and IP 23 enclosure. The alternator is fitted with bearing temperature detectors.
Technical data of alternator
- Rated output kVA 2500 KVA
- Power factor 0.8 lag
- Max. Alternator output at site 2000 KW
- Duty Continuous
- Rated speed 600 RPM
- Rated voltage 400 V
- Rated Current 3608A
- Efficiency at 100% load and 0.8 PF 94.5 %
- Direction of rotation clockwise
- Number of poles 10
- Rated frequency 50 Hz
- Over-speed 20% for 2 minutes
- Overload capacity and duration 10%, for max. 1 hr in every 12 hrs
- Insulation class F
- Enclosure IP 23
- Temp. rise class F
- Excitation and AVR type Brush-less, AVR
- Connection 3w4p
4.2 Governor system for DG
Adopt hydraulic governor.
4.3 Oil storage
Fuel storages and fuel unloading station are arranged near the main building and considered by customers themselves. The fireproof wall must be built around the fuel storages.
There are one 100m3 HFO storage, one 20m3 buffer HFO tank, one 20m3 DO storage, one 5m3 daily HFO tank, one 5m3 daily DO tank and one 5m3 sludge oil tank.
Heavy fuel oil transported by oil truck will be pumped to HFO storage and buffer HFO tank through HFO unloading pump station.
Diesel oil transported by fuel truck (about 30 ton) will be pumped to DO storage and daily DO tank through DO unloading pump station.
For all HFO storage and tanks and sludge tank, steam coil pipes are installed inside and thermal insulations are provided outside.
Fuel temperature in HFO storage is recommended to be 50-60 centigrade degree, fuel temperature in buffer HFO tank to be 70-80 centigrade degree. The buffer HFO tank is used for pre-separation of sludge and water contained in HFO and providing a suitable constant HFO temperature. Gravitational settling of water and sediment in HFO is an extremely slow process due to small density difference between HFO and the sediment. A large fuel oil surface area and a low viscosity are needed for the settling process. The volume of buffer HFO tank is 20m3, which is enough for 24 hours continuous operation at rated load.
HFO in buffer HFO tank will be pumped to the separator modules. The separating capacity is 1000 kilogram one hour. For whole power plant, the maximum HFO consumption one hour is about 500 kilograms. The clean HFO will be pumped to daily HFO tank, and the sludge oil will be pumped to sludge oil tank through the sludge oil pump installed on separator module. Overflow pipe is provided between HFO daily tank and HFO buffer tank.
Heavy fuel oil in daily HFO tank and diesel oil in daily DO tank will be pumped to booster module in generator main building.
4.4. Fuel Circuit system
4.4.1 Type of fuel:
The engines are suitable for operation on HFO (Heavy Fuel Oil) with maximum viscosity 380 cSt at 50 deg. C.
While starting or stopping the engine, diesel oil is used as fuel. When the water temperature at inlet to engine is more than 60 deg.C and the HFO (Heavy Fuel Oil) is heated to the required temperature, the fuel can be changed from DO to HFO through a 3-way fuel valve.
Equipment fitted on the engine:
- Individual fuel injection pump for each cylinder with fuel rack & linkages.
- Individual injector fitted on each cylinder head.
- High-pressure injection pipes
- Main fuel rails for feeding and return.
- High-pressure pipe connection for each cylinder
Equipment delivered loose:
1) One HFO separator set
2) One fuel viscosity control unit (booster) consisting of:
Two electric motor driven fuel feed pump (one for working, one for standby);
Two electric motor driven fuel booster pump (one for working, one for standby);
One duplex type coarse filter;
One pressure-regulating valve;
One steam heater for HFO;
One flow meter for HFO;
One 3 way fuel changeover valve;
One viscometer & temp controller;
One emergency pressure safety valve;
One duplex type fine filter;
One mixing vessel with safety valve;
One pressure-regulating valve in fuel return;
3)Complete interconnecting piping with flanges, fasteners, valves, non-return valves, bosses, supports, etc as necessary up to Day Tank.
Fuel consumption:
The hourly rate of fuel consumption per kilowatt Power delivered at the crankshaft flange at rated power & speed (after running in of the engine & for engine with driven raw water, fresh water & lube oil pumps) is 198.00 gms, when engine operates at Maximum Continuous Rating (MCR).
FUEL CONSUMPTION (with 3 driven pumps)
====================================================
GN8320ZD8 Consumption at
(600 RPM) engine Cr.shaft
gm/kWh
====================================================
100% Load 198.00
SITE -----------------------------------------------------------------------------
75% Load 205.00
CONDITION-------------------------------------------------------------------------
50% Load 215.00
====================================================
The values are subject to a 3% tolerance and apply when burning fuel with a net calorific value of 10,200 KCal/Kg minimum.
4.5 Lube oil circuit system
Oil sump capacity (ltr)
The engine is equipped with a dry sump attached to the bottom of the crankcase. The lube oil for the engine is stored in a separate tank positioned away from the engine. This arrangement offers much more reliability than the wet sump arrangement.
The total oil capacity of this lube oil tank is 1500 ltrs.
Lube oil consumption
The average lube oil consumption is 1.2 gm/kwh (+/- 0.2 gm/kwh) at MCR at crankshaft for a well-run engine.
Equipment fitted on the Engine:
- One engine driven lube oil supply pump
- One engine driven lube oil transfer pump
- One pressure-regulating valve
- One lube oil thermostatic valve (option)
- Complete interconnecting piping with flanges, fasteners, valves, non-return valves, bosses, supports, etc as necessary.
Equipment delivered loose:
- One tank for lube oil (1500 ltrs capacity) with interconnections to the engine
- One electric motor driven lube oil-priming pump (option)
- One manual lube oil-priming pump
- One lube oil cooler
- One centrifugal lube oil filter (FLL75 bypass type)
4.6 Starting air circuit system
The DG is started by the compressed air.
Equipment fitted on the engine:
Compressed air starting equipment including:
- One rotary distributor
- One air-starting valve in each cylinder head
- Connecting air piping on the engine
Equipment delivered loose:
- One electric motor air compressor
- One air receiver of 500 ltrs (30 bar) capacity. This capacity is enough to start the engine 7 times without intermediate refilling of the receiver.
- Complete interconnecting piping with flanges, fasteners, valves, non-return valves, bosses, supports, etc as necessary.
4.7 Cooling water circuit system
The engine cooling is achieved by open cooling water circuit.
Drawn by the water pump from the reservoir, the cooling water flows to the air cooler, and to the injector cooling oil cooler if provided and to the lube oil cooler, and then enters the inlet water main pipe and the turbocharger. The cooling water is discharged out through the outlet water main pipe. Between the inlet water main pipe and the outlet water main pipe there is a thermostatic valve with a sensor at the engine outlet water main pipe, which by-passes part of the outlet water to the inlet of the water pump to keep the water temperature to be not too low. Finally the water is cooled in a cooling tower.
Equipment fitted on the engine:
- One engine driven fresh water pump
- One water-cooled charge air cooler
- One fresh water cooler
Equipment delivered loose:
- One cooling tower (civil construction provided by customer)
- One dosing arrangement for water system (for each D.G. Set).
- Complete interconnecting piping with flanges, fasteners, valves, non-return valves, bosses, supports, etc as necessary.
4.8 Intake air and ventilation system
The air intake system is equipped with air filtration (ABB type installed on the engine) to clean air.
Axial-flow explosion-proof fans opposite to generator shall be arranged for the main building on the engine side. Airflow capacity for each fan is about 20000m3/h.
The axial-flow fans are used for supplying air for the generator and reducing temperature in the engine room through convection. The quantity of heat dissipated from the generator is about 420 MJ/h. The air will be discharged through natural ventilation on the upper side of the main building.
4.9 Exhaust gas and environmental impact mitigatory system
Air pollution prevent
All diesel engines for the power plant are acquired international air pollution prevent certificate according to the provisions of Annex VI of the international Convention for the Prevention of Pollution, 1973, as modified by the Protocols of 1978 and 1997 relating thereto and of the Technical Code on Control of Emission of Nitrogen Oxides From Marine Diesel Engines.
Emission data as follows:
Applicable Nox emission limit (regulation 13 of Annex VI): 12.5g/kWh
Engine’s actual Nox Emission Value: 9.69g/kWh
Noise
The mechanical noise beside the diesel engine at a distance of 1 m is 112 dBA. The mechanical noise will be proofed and reduced by the main building.
The exhaust gas noise is reduced through a residential type silencer to 70dBA at a distance of 1 m.
The exhaust gas from diesel generator flows to exhaust gas pipe (DN400), pass a tee joint, and then divides two ways. One flows to silencer through a butterfly valve, another flows to exhaust gas boiler. When the exhaust gas boiler works, the butterfly valve for silencer will close and the butterfly valve for exhaust gas boiler will open, and then exhaust gas will vent from the chimney on the boiler. When the boiler cannot work normally or the boiler need to be stopped, the butterfly for boiler will close and the butterfly valve for silencer will open, and then exhaust gas will vent from the chimney on the silencer.
One steam exhaust gas boiler is arranged for the power plant. One exhaust silencer (Residential type) is fitted to the generator.
Equipment fitted on the engine:
- Lagged set of exhaust manifold with expansion bellows
- One ABB turbocharger.
- Exhaust outlet connection with expansion bellow.
Equipment delivered loose:
- One exhaust silencer
- One exhaust gas boiler
- Insulation /lagging/cladding for exhaust ducting
- Complete interconnecting piping with flanges, fasteners, t-joints, butterfly valves, bosses, supports, etc as necessary.
4.10 Steam system
One exhaust gas boiler is arranged on the roof of control room. Heat exchange area for the boiler is 67 m2, steam capacity for the boiler is 500kg one hour at 170 degree centigrade and 0.7 Mpa. Steam from boilers will flow to steam main pipe and divide to separator and pump room, oil storage and main building through main steam distributor and steam distributors. The main steam distributor is located on the roof of HFO equipment room, and other steam distributors are located beside the equipments need to be heated.
Drain trap is arranged on the end of steam pipe for equipment need to be heated, condensation water will be not recycled.
Equipments for steam system:
- One exhaust gas boiler
- Two water feed pumps
- Two Steam distributors
- Insulation /lagging/cladding for steam pipes
Complete interconnecting piping with flanges, fasteners, t-joints, valves, bosses, supports, etc as necessary.
4.11 Water soften system for exhaust gas boiler
One water soften equipments are arranged for the power plant, water treatment capacity is 2000kg one hour.
The water soften equipment adopts resin exchanger treatment system.
Equipments for water soften system:
- 1 water soften equipment
- 2 water feed pump
- One water tank
Complete interconnecting piping with flanges, fasteners, valves, bosses, supports, etc as necessary.
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