Energy conservation in
Boilers:
- Control
excess air in combustion which can lead to huge dry flue gas loss. Install
online O2 analyzer for better controlling of excess air.
- Control
Air pre-heater (APH) out let flue gas temperature, it is said that on
every 22 °C rise in boiler outlet flue gas temperature leads to decrease
in boiler efficiency by 1%.
- Optimize
fuel moisture, which can lead to loss due to moisture.
- Installation
of fuel (bagasse) driers for recovering potential heat from chimney inlet
flue gas.
- Control
unburnt in bed ash and fly ash, which can lead heat and fuel loss.
- Maintain
maximum possible feed water inlet temperature at economizer inlet. On 6–7
°C rise in temperature of feed water at economizer inlet leads to 1% fuel
saving. And 15 °C rise can lead to increase in overall thermal efficiency
by 3%.
- Utilize
unburnt from Economiser, bank zones by incorporating Cinder reinjection
(CR) system
- Optimize
boiler continuous blow down to reduce heat loss with hot water
- Create the ideas for utilizing blow down water for heating of combustion air, or feed water and even boiler blow down water can be used for cooling tower make up by reducing its temperature
- Utilize
blow down flash steam for heating feed water in deaerator. Continuous blow
down (CBD) from steam drum operating at 115 kg/cm2 releases 42–45% flash
steam.
- Reduce
boiler pressure if permissible, for process, boiler pressure can be
maintained as per process requirement. This is the most effective way of
fuel saving.
- Incorporate
VFD to all boiler auxiliaries like fans and fuel feeding systems.
- Instead
of throttling discharge air dampers ,provide inlet guide vanes to fans to
control the air flow.
- Arrest
all boiler steam, flue gas and water leakages.
- Operate
boiler on optimum loads, boilers give more efficiency at 65–85% of full
load.
- Inspect
air distribution nozzles, dampers regularly.
- Try
to get maximum temperature of combustion air by incorporating Steam coil
air preheaters (SCAPH).It is said that on every 20 °C rise in combustion
air temperature leads to increase in boiler efficiency by 1%.
- 10–12%
of hot air recirculation into FD fan suction can maintain rated APH inlet
air temperature, which can lead to elimination of SCPAH thereby reducing
LP steam consumption.
- Utilize
DG exhaust flue gas temperatures for heating systems like combustion air,
feed water etc.
- Operate
the soot blowers regularly to remove soot formed on heating surfaces. It
is estimated that 2.5% of fuel consumption will increase on deposition of
3 mm soot on heating surfaces of pressure parts.
- Operate
boiler feed pumps at rated or maximum possible suction pressure to reduce
auxiliary power consumption.
- Incorporate
VFD to boiler feed pumps and reduce speed whenever possible
- Operate
feed water control valve at maximum opening i.e. control valves should
open 70–80% for normal operation. It will reduce the pressure drop in control
valves and hence load on boiler feed pumps.
- Attend
the the leakage of Boiler feed pumps ARC valves.
- Use
Neutra pit water or ETP treated water for ash quenching and other
services.
- Use
Neutra pit water or ETP treated water for ash quenching and other
services.
- Operate
the pneumatic ash handling system in probe mode instead of timer mode to
save the compressor power.If run in timer mode optimise ash conveying time
& cycle time.
- Use
high temperature coatings for valves, lines etc. o reduce heat loss.
- Optimize
deaerator steam vent line and orifice size to avoid excess steam vent or
utlise this vent out steam for heating combustion air.Deaerator steam vent
loss is around 0.1 % of Boiler steam generation.
- Remove
air from indirect steam using equipments, as 0.25 mm thick air offers the
same resistance to heat transfer as a 330 mm thick copper wall.
- Maintain
water quality to avoid boiler scaling. A 1 mm thick scale deposit in the
water side could increase fuel consumption by 5–8%.
- Insulate
all hot water storage tanks.
Energy conservation in
Fuel handling & storage system:
- Always
store fuel in fuel shed to avoid wetting and excess drying of fuel in
rainy and summer seasons respectively.
- Store
fuel on PCC (Plain cement concrete) bed to avoid carpet loss of fuel.
- Cover
fuel yard and storage shed by trees (bamboo) to reduce handling and
feeding loss of fuels during high wind speed.
- Conveyors
should have seal proof hood covers to avoid flying/escaping of fuel during
high wind speed.
Energy conservation in
Turbine and its auxiliary system:
- Maintain
maximum rated pressure at Turbine inlet to achieve less SSC.
- Maintain
maximum possible vacuum to reduce SSC.
- Maintain
optimum cooling water inlet and outlet temperatures for all heat
exchangers like steam condensers, oil coolers and Generator air coolers
- Optimize
cooling tower blade angles, more the angle more the power consumption.
- Reduce
the clearance between CT fan blade and concrete hood or fiber hood;
generally it should be up to 25–30 mm.
- Provide
VFDs to cooling tower fans and Main cooling water pumps to control speed
as per requirement.
- Replace
all aluminum blades by energy efficient FRP blades.
- Clean
cooling tower water spray nozzles regularly.
- Arrange
drift eliminators and fills properly for uniform spreading of air and
water.
- Clean
condenser and ejector tubes yearly to achieve proper heat transfer
- Keep
cooling tower surrounding free from structures, building, trees to enable
free air movement.
- Ensure
cooling water pump top casing crub level is below the normal operating
level of cooling tower toavoid carrying of air in water or it may lead to
cavitation.
- Make
a provision for online backwash systems for surface condenser and oil
coolers to improve heat transfer.
- Clean
oil pumps filters regularly.
- Incorporate
VFD to Condensate extraction pumps (CEPs).
- Install
condensate recovery system from all process line drains and traps.
- Use
CEP discharge water instead of BFP discharge water for desuperheating of
low pressure process steam.
- Select
optimum head condensate extraction pumps. If Deaerator working pressure is
2.75 kg/cm2A CEP of 80 meter discharge head considering all losses is
sufficient.
- Try
to get maximum percentage of condensate from processes.
Energy conservation in
other balance of plant (BOP) areas:
- Replace
all globe valves by ball valves of instrument pressurized air.
- Clean
suction air filters of compressors regularly as 250 mmwc pressure drop in
suction filter will lead to the reduction of compressor efficiency by 2%.
- Opening
of air filters should be sufficient to suck enough air.
- Locate
compressors at lower level as at higher elevation compressors consume more
power.
- Install
compressors in well ventilated areas.
- Ensure
cool water and air for compressors air cooling system. At every 4 °C rise
in inlet cooling water temperature will increase power consumption by 1%.
- Clean
after and inter coolers regularly to get better heat transfer.
- Install
auto moisture drains for air lines.
- Avoid
unnecessary use of compressed air for applications like cleaning, washing,
pneumatic tools etc.
- Optimize
discharge air pressure of compressor, on reduction of 1 kg/cm2 discharge
air pressure leads to input power saving by 6–10% And on reduction of
discharge air pressure by 1 kg/cm2 will reduce air leakage by 10%.
- Carryout
periodic air leakages test.
- Prefer
two stage reciprocating air compressors over single stage for same FAD and
pressure as single stage compressors consume much power than multi stage.
- In
centrifugal fans (ID, FD and SA fans) Maintain optimum cone clearance and
overlap gap to reduce power consumption.
- Provide
optimum height silencers for high speed centrifugal fans and take
care the silencer is free from all obstacles.
- Modify
ducting system by removing all obstacles to avoid pressure drop.
- Incorporate
VFDs to ventilation blowers to control speed during low temperature season
(Winter and rainy seasons).
- Provide
VFDs to all possible pumps.
- Replace
all loose V belts as loose and damaged V belts conribute in more power
consumption
- Timely
checking of equipment vibrations and alignment to avoid unnecessary power
consumption and machine failure.
- Avoid
over greasing of bearings to reduce churning effect and energy
consumption.
- Replace
higher rated capacity pumps with rated to avoid running of higher capacity
pumps under load.
- Replace
all worn out wear rings of impellers and casing, as more clearance between
wear ring and pump suction will contribute in more power consumption to
maintain required flow.
- Instead
of controlling discharge valve, impeller trimming is the best way to
control flow and power consumption.
- Use
booster pumps for small loads requiring higher pressure.
- Provide
all measuring instruments like flow, pressures for pumps to monitor their
performance regularly.
- Avoid
bends and U seal pattern for suction line of pumps.
- Use
mechanical seals over gland packings.
- Avoid
connecting small size pump discharge line to higher size header, the ratio
of header and discharge line should be in the range of 1.3 to 1.6 only.
For higher size ratio power consumption will be more.
- Replace
all conventional gear boxes like worm-worm wheel and helical by more
efficient planetary gear box.
- Replace
DOL starter motors of heavy equipments like chain conveyors with soft
starters.
- Modify
the chain conveyor system to reduce unwanted dead loads like slat weights,
link size etc.
- Incorporate
timers of street and plant lighting system.
- Replace
all the plant lighting bulbs by high efficient LED bulbs.
- Maintain
higher power factor at all the load ends by installing capacitor banks to
reduce excess reactive power.
- Provide
forced cooling system for higher capacity power transformers to reduce
losses.
- Provide
proper ventilation to the motors. For every 10 °C increase in motor
operating
- temperatures
over recommended peak, the motor life is estimated to be halved.
- Synchronous
motors are more suitable to improve power factor.
- Balance
the three phase power supply, an unbalanced voltage can increase motor
input power by 3–5%.
- Ensure
the motor proper rewinding, an improper rewinding could lead to efficiency
reduction.
- Ensure
proper alignment between motor and load ends (fans, pump, gear box, blower
etc.) to avoid more power consumption and failures.
- Optimize
the quantity of lubricants in bearings and gearboxes to reduce unwanted
load due to excessive lubricants.
- Provide
an alternate arrangement for connecting river water directly into
clarifier; it will save power consumption for lifting water from reservoir
to clarifier.
- Prefer
gravity make up system for condenser hot well make up, it will save pump
power for hot well
Good article
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ReplyDeleteNice Article
ReplyDeleteThe points are valuable.
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