Bio Heat Plant Equipment

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Bio Heat Plant Equipment
Intensive Course for Renewable Energy Joensuu,
Finland, 18th Sept, 2009 Petri Rousku North
Karelia University of Applied Sciences
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Fuel storages and dischargers
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Wood chip storages

• Push feeder floor (moving floor) discharge
  hydraulic (for large storages)
• Containers with push feeder floor discharge

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Steel element silos

• Spring unloader
• Picture www.megakone.fi
• Rotating plate unloader

Megakone
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Pellet silos

• Gravitational
• for pellets only!

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Fuel storage

• Minimum volume for heating entrepreneur fuel
  amount sufficient for 3 days on top power
• What kind of vehicles for supply? -gt structure
• Flat terrain or hill?

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Fuel conveyors
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Augers
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Chain conveyor

• Better performance
• Transfers larger particles through it than an
  auger
• But needs maintenance

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Pneumatic conveyor for pellets

• Transfer distance gt20 m
• Loose dust separation included in the Finnish
  system
• Suitable for every places, but more expensive
  than auger

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Wood fuel storage conveyors Middle-European
application
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Fuel feeders and burner heads
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1. Small scale for premises
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Stoker burner principle
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Small stoker burner, fixed burner head
Säätötuli
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Pellet burner mechanical burner head
Ecotec
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2. Feeders for larger scale
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Chip feeders

• Stoker auger
• Hydraulic piston

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Boilers and combustion techniques
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Boiler

• Usually a good, industrial, standard product
• Efficiency factors
• Smoke temperature
• Insulation
• More attention to combustion techniques and
  control techniques!

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Grate boiler
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Automation, control

• Simple automation OR
• Complex programmable logics control (PLC)

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Adjustment principles

• a. Conventional on-off feed with clock-switch
• fuel and combustion air portably feeding with
  top power till boiler top temperature reached --gt
  break on feed
• simple, easy to adjust, but flue gas emissions
  alter
• high power demand for electric motors of fuel
  feeding augers
• OR

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• b. Modulating fuel and combustion air feed with
  inverters
• vast adjustment possibilities, but more difficult
  to adjust at first
• quick reaction to load changes
• enables low fluegas emissions in every situation

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Other things to consider

• Grate boilers/ stoker burners

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• secondary combustion air regulation based on
  fluegas O2 content emission level
• Lambda sensor
• Zirkonia oxygen probe

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Pellets, briquettes

• High combustion temperature
• -gt water-cooled grate recommendable

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Electricity back-up

• UPS?
• Accumulators?
• Aggregate?
• None?

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Alarm system

• GSM modem with text message inquiries
• Alarm classifications
• Telephone alarm
• Alarm signal lights

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Instrumentation, meters

• Pressure, temperature metering
• Pumps and blowers
• Safety over-heating, over-pressure
• In Finland gt1 MW
• gt double instrumentation!

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Back-fire prevention

• Pressurized water with thermoelement and valve
• gravitational water tank

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Energy meters

• Magnetic
• When turbulence
• needs annual cleaning
• Ultrasonic
• When impurities in the water
• Needs straight piping

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Ash removal, sweeping

• Automatic/ manual boiler sweeping
• Ash removal by auger or chain conveyor
• Wet/ dry
• Fuel quality?
• Coditions?
• Ash container size?

Schmid
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Smoke

• Blower or free flow?
• Blower with modulating adjustment -gt efficiency
• Chimney diameter and length
• Cyclone /multicyclone
• Scrubber
• No cleaning?

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Other combustion techniques
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Gasification boiler

• very good combustion results on different solid
  fuels possible
• operation principle power adjusted by
  controlling the gasification of the fuel already
  present in the boiler (compare grate boiler
  output controlled by the momentary fuel feed and
  combustion air)
• Power range 5gt100 , but no sudden load changes

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Primary combustion chamber fire tube boiler

• the gas produced in the primary chamber is burned
  in a separate boiler
• typical for fuels with high moisture content
• Power range 20gt100

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Fluidized bed combustion

• hot sand and fuel fluidized together in the
  combustion chamber -gt very good combustion result
  with wet fuels of varying quality
• typical at modern power plants
• not very adjustable
• small-scale solutions in the future?

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Turbulated combustion

• Lengthened combustion time
• gt very complete result

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Alternative heating container

• Easy acquisition complete product
• Not cheap
• Limited fuel storage
• Placing apart from other buildings