Power / Cogen

As one of SOMEC's main business, thermal power plants have been promoted to overseas in recent years. Taking advantage of the mature technology and high-quality products from China, as well as 20-years experience for overseas projects, we have made achievement in the fields of EPC projects, complete plants, equipment supply, engineering services and so on.

POWER PLANT AND COGEN PLANT

Thermal power plant covers several different types, such as full condensing,single-extraction (steam extraction with one certain temperature / pressure), double-extraction (steam extraction with two kinds of temperature / pressure) , back pressure (make use of the exhaust steam) and combined type (extraction and back pressure), to meet the different kinds of requirement of the owner. Usually the power plant of extraction type and back pressure type be named as "Cogen plant", because they produce not only electricity but also steam (external supply). Cogen plant and full condensing power plant are both widely used, mainly for electricity supply to state grid as well as electricity / steam supply to some certain enterprises.

Theoretically, cogen plant has a higher overall efficiency than full condensing power plant because of the reuse of extracted steam and/or exhaust steam. It is suitable for the users with requirement of both electricity and steam, such as food/oil/pharmaceutical processing plant, ethanol plants, sugar mill, paper mill, chemical plant, wood processing plant, etc. While most of full condensing power plants built for electricity supply to state grid, which is near to a coal mine or at a place with convenient transport of coal.

Power plants of small and medium size normally refer to the following four parameters to choose BTG and systematic equipment and material. We will select for our customers the most suitable one(s) considering the scale, local conditions, operating level of staff, input-output ratio and such factors.

  Turbine steam inlet  
Super high pressure: 540℃ / 555℃ 13,7MPa
High temperature & pressure: 535℃ 8.83MPa
Sub-high temperature & pressure: 470℃ 4.9MPa
Medium temperature & pressure: 435℃ 3.43MPa

 

SYSTEM CONFIGURATION

Several power plants have been built for our local and overseas customers. For the comparison of the usual configuration between cogen type and full condensing type, we take two plants (one of each type) as sample, both built in Indonesia and have the same capacity 2x7MW, as follows:

Basic Information

  COGEN (put into operation in 2006) POWER (put into operation in 2008)
Customer (Owner) Food processing enterprise
(electricity and steam supply to
the enterprise)
Coal mining enterprise
(electricity supply to the mine  and state grid)
Power capacity 2×7MW (Gross) 2×7MW (Gross)
Steam extraction ≤50t/h, 330℃, 0.981Mpa -
Fuel Coal  (transported from outside) Coal  (self-produced)
Boiler type CFB boiler 
(medium temp. & pressure )
Stoker boiler  
(medium temp. & pressure)
Turbine type Extraction-condensing Full condensing
Water source Well water Sea water
Geological condition Designed for magnitude
8 earthquake prevention
Designed for magnitude
7 earthquake prevention


Main System Configuration

Boiler 3×45t/h CFB boiler
 
2×40t/h Stoker boiler
Turbo-generator unit 2×7MW Turbo units
3000r/min, 6300V
2×7MW Turbo units
3000r/min, 11000V
Coal handling system Belt conveyor, including secondary
coal crusher
Bucket elevator, without secondary
coal crusher
Boiler bed material system Equipped -
Limestone system Equipped -
Ash / slag
handling system
Including 4 fields ESP Including 3 fields ESP
Water treatment system Fresh water R/O desalination,
capacity: 50t/h
Sea water R/O desalination,
capacity: 8t/h
Circulating cooling 
water system
Fresh water close circulation
 
Sea water close circulation
(cooling tower)
HV electrical system Isolated network,  no substation Synchronize with state grid, 
equipped with substation
LV electrical system Including service transformer
 
Including service transformer
(1100/400V)
DCS + Instruments Honeywell Siemens
Steam system 
(for external supply)
pressure & temp. reducer,
cylinder, etc.
-
Communication system Equipped Equipped
Fire fighting system Equipped (by owner) Equipped (by owner)
Building illumination Equipped (by owner) Equipped (by owner)
Ventilation and AC Equipped Equipped (by owner)
Others    

Auxiliary equipment of above plants, such as water pumps, ID fans, FD fans selected 400V motors; while for power plant above 30MW, the voltage of motors usually be 6300V or 11000V.

Remark:
• A certain over-generating ability have been considered during design and equipment selection;
• Both plants adopt common header design, flexible operation.
• Above configuration is just for reference and should not be copied. Each power plant shall be specialized
  designed according to actual conditions.