September 2010 1 Wood to Warmth – Fuel Delivery and Storage Michael Beech TV Energy.
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Transcript of September 2010 1 Wood to Warmth – Fuel Delivery and Storage Michael Beech TV Energy.
September 20101
Wood to Warmth – Fuel Delivery and Storage
Michael Beech
TV Energy
September 20102
Fuel Delivery & Storage
Pellets – delivery and storage
• Domestic systems: 10 or 15 kg bags of pellets can be loaded manually into an integral hopper attached to boiler
• Larger systems: 15tonne pellet tanker or larger for bulk delivery – concept similar to oil
• Size store for boiler consumption at full load and largest volume practical to allow lowest £/tonne as a bulk delivery
• Pellets can be blown into an above ground store via flexible tube, up to 30m if necessary – but the shorter the better
• Minimise bends in delivery tube to reduce pellet damage
• Fuel transfer to boiler by lightweight or flexible auger feed
September 20103
Fuel Delivery & Storage
Pellets
September 20104
Fuel Delivery & Storage
Woodchip – delivery and storageConsider carefully:
• Delivery vehicle access to fuel store• Types & sizes of delivery vehicle• Method of transfer of woodchip from delivery vehicle into
store• Storage capacity sized for boiler consumption at full load and
lowest £/tonne of woodchip (largest delivery volume practical)• Maintenance access to fuel store and boiler feed auger in
case of fuel quality problems• Ventilation within fuel store to prevent condensation causing
saturated chip
September 20105
Fuel Delivery & Storage
Type and arrangement can be determined by method ofwoodchip delivery. Common arrangements are:
Woodchip Store - 1
• Above ground, walking floor transfer, open at one end. • Vehicle can drive into storage area and tip (or offload using
moving floor) onto walking floor ladders, which transfer chip to one end towards auger feed to boiler.
• Can also accept deliveries from front loader vehicle, or direct from chipper.
• Walking floor mechanism requires significant civil works & hydraulics, therefore expensive
• Robust system if designed and installed correctly
September 20106
Fuel Delivery & Storage
Above ground store, walking floor transfer
September 20107
Fuel Delivery & Storage
Above ground store, walking floor transfer
September 20108
Fuel Delivery & Storage
Above ground store, walking floor transfer
September 20109
Fuel Delivery & Storage
Woodchip Store - 2
• Above ground store, rotary arm agitator feed to boiler, fully enclosed or part open on one side.
• Vehicle will offload from above, in through hinged/ sliding opening or hatch. Requires chip volume to be raised and tipped, front loader or scissor lift trailer are suitable.
• Use of a chip blower (trough type or integral to container vehicle) is a further alternative, though relatively slow, noisy and energy intensive.
• A vehicle ramp or bank up to one side of store can allow use of standard tipping vehicle.
September 201010
Fuel Delivery & Storage
Above ground store, rotary agitator
September 201011
Fuel Delivery & Storage
Above ground store, chip blowers
September 201012
Fuel Delivery & Storage
Above ground store, delivery methods
September 201013
Fuel Delivery & Storage
Woodchip Store – 3
• Containerised storage (Roll on roll off/ hook lift bins). A fuel store and transport container in one.
• Bins are specially designed with walking floors and connection to feed auger, part of docking station. Usually 3 docking stations required, bins ~30m3 each.
• An expensive system, requires good a deal of space, but affords clean woodfuel delivery
• Mechanisms and connections prone to damage
September 201014
Fuel Delivery & Storage
Containerised Storage
September 201015
Fuel Delivery & Storage
Woodchip Store - 4
• Below ground store: Both walking floor and rotary arm agitator systems can be designed to be below ground, allowing standard tipping vehicles/ trailers or moving floor container vehicles to be used to transfer chip into store under gravity.
• Allows simplest and quickest delivery method, wide range of vehicles and hence fuel suppliers can be used
• High excavation costs, pit needs to be waterproof.• If plant room is at ground level then woodchip feed auger must
route upwards with maximum 30deg. angle from horizontal, to connect to boiler.
September 201016
Fuel Delivery & Storage
Below ground storage
September 201017
Fuel Delivery & Storage
Below ground storage
September 201018
Fuel Delivery & Storage
Example calculation
Woodchip @ 30%MC Wood pellets
Estimated peak heat demand (winter design condition) 16.0 16.0 hours/day at full loadHeat output capacity 220 220 kWBiomass boiler seasonal effi ciency 88% 88%Woodfuel energy 3,300 4,700 kWh/tonneMaximum woodfuel input rate 250 250 kWh/hr at full load
75.8 53.2 kg/hr at full load1.21 0.85 tonnes/day
Estimated bulk density of woodfuel 0.24 0.6 kg/cu.m5.05 1.42 cubic m/day
Woodfuel delivery vehicle minimum capacity (min. storage capacity) 5 15 tonnesWoodfuel delivery vehicle type tractor/trailer pellet tanker
21 25 cubic metresNo. of days of operation at peak heat demand per delivery 4 18 daysApproximate number of deliveries required for annual heat load 18 4 /yrDepth of woodfuel store 3.0 3.0 mInternal width of woodfuel store 5.0 3.25 mInternal length of woodfuel store 5.0 3.25 mInternal volume of woodfuel store (gross) 75.0 31.7 cubic metresEstimated usable volume of woodfuel store 50.6 29.0 cubic metres
12.2 17.4 tonnesNo. of days of operation at peak heat demand 10 20 days
September 201019
Fuel Delivery & Storage
Common problems
• Storage capacity too small - requires frequent deliveries• Difficult access to fuel store – increases delivery times, smaller
than optimal capacity vehicles used• Poor design of access opening into fuel store – chip spillage• Inadequate ventilation within fuel store – condensation from
chip causes drips from roof onto top layer causing wet chip• Double handling of chip (offloading then delivering into store)• Inadequate provision made for maintenance access to fuel
store, woodchip agitator/ transfer equipment, feed augers • Fuel delivery and storage are most likely areas for failure
of biomass systems, due to poor planning and design
September 201020
Thank [email protected]