Document - PPT - Saving Energy.pptx
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CIMENT SAVING ENERGY A summary about electrical and thermal energies consumptions OLIVIER TERVER
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Transcript of Document - PPT - Saving Energy.pptx
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SAVING ENERGY
A summary about electrical and thermal energies consumptions
OLIVIER TERVER
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Summary
1.The Electrical energy
2.The Thermal energy
3.Applying the theory in Peille
4.Conclusion
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What energy for cement manufacturing ?
Thermal Energy850 kcal/kg ck
Electrical Energy130 kWh/t cem
Thermal Electrical
2 850 MJ/t cem 468 MJ/t cem
10.54 €/t cem 7.80 €/t cem
The energy used to produce cement is of two kinds :
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Energy or Specific Energy ?
All figures relate to a tonnage
Optimizing might be done withThe energy
The tonnage
Each process is subject to its own optimization sensibility.
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1. Factors impacting the Electrical Energy
Overview of the main actions to be taken per plant section
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The electrical consumers
Identifying the consumers to help target the actions.
Breaking down the consumptions of plant sections
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Determining the actions : Cement grinding
Energy split:
80% used by the ball charge20% used by the equipment
Sustainably decreasing the specific electrical consumption is only possible by increasing the mill throughput:
Optimizing the mill process parameters(including ball charge repartition)
Improving the clinker reactivity (to gain on fineness)
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Determining the actions : Raw mill
Energy split:
That plant section is balanced between mill power and fan power. VRM offers higher flexibility for electrical savings than ball mills.
The power on the table is driven by the grinding pressure and the bed depth of material. The fan power is driven by the flow, thus the speed profile within the mill.
Optimizing the dam ring and grinding pressure
Reducing the air flow in the mill if possible by favoring external recirculation
Increasing the mill throughput working on differential pressure
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Determining the actions : Kiln
Energy split:
The biggest motors being on the fans, the gas ways are the key to electrical savings on a kiln line.
There is a huge amount of energy in play within the gas ways. The gas flows are impacted by various parameters such as the combustion, the oxygen content, the false air.
Optimizing the kiln burning conditions to reduce air volume
Decreasing the entry of false air
There is usually no easy kiln throughput upgrade to increase tons
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Determining the actions : Kiln – ID Fan
The ID fan represents 28% of the total kiln section electrical consumption.
This sole equipment is 5% of the total plant electrical consumption.
Less exhaust air
Less thermal loss
Less heat consumptio
nOptimizing the ID fan has a great impact on the overall
performances.(electric and thermal)
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2. Factors impacting the Thermal Energy
What to look for to reduce thermal energy
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Note on thermal energy
The electrical energy is mostly related to a mechanical force which requires a mechanical modification to change:
Reducing the grinding energy requires a change in ball charge or on the dam ring height.
The thermal energy (except radiation) allows more leverages than the electrical energy because it is a combination of temperature and flow.
Reducing the preheater thermal losses can be done by decreasing the outlet temperature and/or the outlet flow.
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Overview of a thermal balance
A heat balance is mandatory to follow up on losses, which are the main factors for thermal energy leaks.
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Overview of a thermal balance
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Determining the actions on heat losses
Transformation – 48%• Adapting cement modules• Changing raw mat cristallography
Cooler losses – 14%• Improve the heat transfert• Reduce false air• Increase secondary air temperature• Decrease clinker temperature entering cooler
Preheater losses – 23%• Reduce false air• Decrease oxygen in kiln inlet• Improve heat transfer• Decrease volume of combustion gas
More likely to be done
Less likely to be done
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3. Applying the theory…
Example of one of the actions done in Peille
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Example of energy saving in Peille
The focus has been set on false air entries all around the plant.
1. Sealing holes in cyclones and down comer duct2. Sealing holes in the kiln main baghouse3. Sealing holes in the cooler vent system
The process parameters have not been modified significantly to aim for a reduction of energy, the target at hand being the increase of substitution.
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Example of energy saving in Peille
Gain of 1.22 kWh/t on the kiln area
Almost no gain in the cooler area
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Example of energy saving in Peille
Reducing false air entries
ID Fan:
Specific volume decreased from 1.75 to 1.5 Nm3/kg ck
Specific consumption decreased by 1.1 kWh/t
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Example of energy saving in Peille
Less exhaust air
Less thermal loss
Less heat consumption
Remember this ?
Did it happen ?
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Example of energy saving in Peille
Gain of 25 kcal/kg ck
Does it correspond to the decrease in preheater
loss ?
Calculating a heat balance using 1.75 and 1.5 Nm3/kg ck for the outlet of the preheater gives a thermal balance going from 864 to 836 kcal/kg ck, so 28 kcal/kg saving. It matches the actual values.
But you can check it also in 2 min only by using the values of this presentation.
So, your turn ….
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Example of energy saving in Peille
Initial Heat Balance of 864 kcal/kg ck
Preheater losses represent 23%
Losses by the preheater outlet add up to198 kcal/kg ck.
Losses are directly proportional to the flow which goes from 1.75 to 1.5 Nm3/kg ck
The new losses are going to be 170 kcal/kg ck and thus the saving is 28 kcal/kg ck
All the other parameters are the same (exhaust temp, secondary air temp, O2 at kiln inlet…), the saving is on the ID fan.
The savings obtained by reducing the ID Fan flow are 25 kcal/kg ck and 1.1 kWh/t ck
The financial saving is 0.5 €/t ck
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4. Conclusion
What is in it for me?
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Conclusion
Saving energy can be a prime goal, like reducing the specific energy of a plant section
It will lead to mechanical changes in mills, or blocking air entries in gas ways
But energy saving can also be a consequence of other works
Upgrading a plant section throughput will decrease the specific energy consumption
Decreasing a clinker temperature for the sake of mechanical equipment will lead to thermal energy saving
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Conclusion
On the other hand, some technical decisions or situations may have a hidden negative impact on energy costs.
A limited cooler venting system will prevent the decrease of O2 at the kiln inlet and thus will cut on electric and thermal savings
Downgrading the filler composition may help the kWh/t of the raw grinding but will impair those of the cement grinding. There may be more loss than gain.
Excessive transportation air on the burner will have a huge impact on both thermal and electrical energies.
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Conclusion
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•Energies are in the core of any technical choice.
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•It is important to address them and estimate the energetic outcome of a decision.
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•Calculating the energetic impact is not always easy.
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•Turning the results into economical figures can sometimes be surprising and may help the decision.
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Conclusion
QUESTIONS ?
