Energy Efficiency In The Cement Ind: Complete Guide & Downlo

Energy Efficiency in the Cement Industry is the collected knowledge volume of the European cement energy transition: the book edited by J. Sirchis, published from the dedicated EC research program: a selection of expert papers on the energy saving in the cement making: the wet and the dry process, the heat recovery, the process control, the fuels, the case studies of the national industries: the reader receives the whole panorama of the European cement plants of the age of the energy audits, with the measured numbers of the savings achieved and the methods that made them.

The Complete Cement Technical Package (931 files including the books, the Excel tools, the courses and the presentations: $249.99 one-time: instant download via the PayPal payment) includes this Energy Efficiency volume PDF with its case studies and process engineering chapters: the plant engineer, the energy manager and the investor read the classic discipline of the industry: the GJ per tonne, the kWh per tonne, the trends of the process: this article walks the terms of the book: the energy anatomy of the plant, the process routes, the heat balance, the recovery technology, the control, the alternative fuels, the audits and the results: the reader finishes with the complete methodology of the cement energy saving.

The energy question remains the first question of the cement: the industry historically spent 12-15% of its cash cost on the fuel and power: the modern dry process tightened that to 6-10% of the operating cost, but the energy crisis of the new century returned the pressure: the clinker needs approximately 3.0 to 4.0 GJ of the heat per tonne and the cement 95-120 kWh of the electric per tonne: the margin between the best and the average plant is still 30-40% of the energy content: the industry’s saving archive is the foundation of the coming carbon economy: the book of Sirchis counts the paths, and this article summarizes the count.

1. The Energy Anatomy of the Cement Plant

The first discipline of the book: the energy map: the flow of the heat through the cement plant from the fuel pile to the product:

• The thermal balance of the kiln: of the 100% of the fuel heat: the clinker gains the clinker’s own heat ~1.75-2.00 MJ/kg (the “clinker heat”), the preheater exit gas carries ~15-25%, the cooler exhaust 5-10%, the radiation of the shell 5-10%, the evaporation and the other losses the rest: the modern kiln holds the net heat to 3.0-3.4 GJ/t; the older wet process loses the huge evaporation of the slurry;
• The electric bill: the cement manufacture spends 25-35 kWh/t in the raw circuit, 30-45 kWh/t in the finish cement, and the rest in the auxiliaries: the fans of the kiln and the raw mill are 20-30% of the electric, the mills 60-70% of the total power: the ranking of the biggest consumers is the ranking of the saving projects;
• The units that govern: the book fixes the units at the start: the MJ/kg of clinker, the kWh/t of cement, the kcal/kg for the old school books, the liter/tonne of the fuel oil parity: the conversion tables are the appendix of the chapter: the engineer of the energy must speak the one language before the audit of a plant, and the book teaches the conversion roll-call;

The energy anatomy is auditing: the plant of the book builds the energy balances of the kiln, the mills, the fans and the compressors: the balance is the parent of all the savings: the plant that cannot weigh its heat cannot destine its capital: the audits of the national energy programs (the chapters of every country) start exactly with this: the measured balance sheet is the first deliverable of the energy engineer.

2. The Wet, the Semi-Wet and the Dry: The Process Ladder

The book devotes a large part to the process selection, the largest variable of the industry: the comparison of the four families:

• The wet kiln: the slurry at 30-40% water: the heat of the evaporation in the kiln itself: the specific heat 5.5-6.5 GJ/t, the water of the plant forever in the fuel bill: the quality advantages of the slurry but the double fuel: many European factories of the book have converted from the wet to the dry in the years of the program;
• The semi-wet and the semi-dry (Lepol): the filtration and the pelletizing: the 4.5-5.5 GJ/t: the middle path of the transition: the book has the conversion cases: the filter press plus the converted kilns;
• The dry process with the preheater: the cyclone tower of 4-6 stages: 3.2-3.6 GJ/t: the moisture of the raw meal is dried by the kiln exit gas: each added stage recovers a share of the exhaust heat but adds the pressure drop: the engineering optimization of the stages is the classic material of the chapter;
• The dry with the precalciner: the calciner beyond the preheater, the fuel split 30-40% in the kiln and 60-70% in the calciner: 3.0-3.4 GJ/t and the production margin 2-3 times of the classic kiln: the modern standard of the large plants;

The book measures the gap honestly: the wet kilns of the 1980s still ran the 5.5-6.5 against the dry’s 3.2: the difference of the fuel per tonne of clinker doubled the energy cost of the cement grade: the programs of the European industry (the energy conservation programs of the EC) co-financed the modernizations: the converted plants repaid the fuel difference in 5-8 years: the case studies of the book document each converted line with the before and the after.

3. The Heat of the Kiln: The Recovery and the Losses

The interior of the thermal chapter: the destiny of every mega-joule of the fuel as the clinker, the exit gas, the shell and the cooler:

• The clinker heat: the clinker leaves the kiln at 1,300-1,450 C: its sensible heat ~1.3-1.8 MJ/kg: the cooler reclaims the lion’s share: the recovery 60-70%: the modern grate coolers push to 75%: the rest is the cooler exhaust gas at 250-350 C or the heat of the kiln boundary;
• The exit gas of the preheater: 280-340 C: this gas goes to the drying of the raw material (the raw mill) and the coal (the coal mill): the margin heat after the mills, ~100-150 C: this is the domain of the waste heat recovery power plants (ORC/steam): the book includes the recovery cases with the modern towers and the flash dryers;
• The shell and the radiation: the exposed kiln shell is the “unavoidable” 5-10% of the thermal: the refractory of the magnesia and the calcium, the thin kiln coating, the shell temperature policy: the book covers the surface measurement and the heat-loss tables: the insulation of the preheater body and the ducts adds the savings from the seams;
• The false air: the air ingress into the kiln system, the mills, the ducts: each 1% of the false air demands extra heat to heat: the leaks at the flanges, the seals, the bypasses: the heat balances of a plant almost always reveal the false air leakages: the chapter teaches the identification: the pressure measurements, the O2 profile, the repair;

The summary of the book: “the heat budget of the kiln is never the problem of the kiln alone”: the preheater, the cooler, the mills, the ducts and the seals form the coupled system: the classic error is the single-lever approach: the book offers the integration: the heat cascade to the mills and the quality of the exit gas: every stream of the plant is a resource for the next unit, and the balance sheets of the book put a number on every transfer.

4. The Energy of the Grinding: The Power of the Mills

The electric side of the energy: close to 60-70% of the plant power is the grinding of the raw meal and the cement: the chapter on the machines and the circuits:

• The ball mill circuit: the classic: 2-3 chambers with the separator: the efficiency: the media grading of the compartments, the classifier: the kWh per tonne depends on the hardness of the feed, the fineness, the moisture;
• The vertical roller mill: the raw meal and the cement: the grinding of the bed, the internal classification, the drying inside the mill: the typically 15-30% less power than the ball circuit: the compact mill: the residence in the mill, the controlled bed: the particle size distribution of the roller pressed vs the ball mill curve is the book’s comparison;
• The high pressure grinding roll (HPGR): the pre-grinding or the final stage: the high pressure creates the flake: the 20-40% lower: the combination with the ball mill and with the cage roller: the book covers the modern circuit and the feed quality;
• The separator and the fan: the third generation classifiers (the cage) vs the first generation: the classification efficiency: the fan power of the system is 40-50% of the mill: the high-efficiency fan, the speed control (the VFD), the auxiliary of the mill: the motors of the air circuit;

Each plant of the book presents its grinding optimization: the mill tests: the compromise between the Blaine gain and the kWh: the quality of the cement (the early strength, the water-to-cement) constrained: the typical saves of the program: 10-20 kWh/t of the cement from the systematic optimization: the money of the industrial scale: the grinding is where the electric saving is the easiest to measure and the hardest to keep.

5. The Fans, the Compressors and the Servants: The Auxiliary Energy

The forgotten majority of the plant: the fans of the kiln draft, the raw mill, the cooler, the compressors, the feeders: the book’s chapter:

• The main fans: the induced draft fans of the kiln: the largest motors after the mills: the efficiency of the fan itself only 70-85% at the design point: the throttling by the damper wastes, the guide vane controls and the VFD saved: the fan laws say the power grows with the cube of the speed: the CFD of the ducts and the bends:
• The compressed air: the plant’s “fourth utility”: the leaks of the pipework, the tools of the dry, the instruments: the typical plant loses 20-40% in the leaks: the book: the audit of the pressure, the nozzles, the capacity control, the checks of the leaks: the pneumatic conveying of the cement: the compressed air team of the ceremony;
• The pumps: the drives of the water circuits: the oversized pumps throttled by the valves: the trimming of the impeller: the circulation flows: the easiest kWh of the annex;
• The motors and the lighting: the motor efficiency classes (the IEC IE1-IE4), the rewinds, the proper sizing vs the oversized: the motor management of the plant: the lighting of the service buildings (the LED, the daylight): the book completes the chapter with the practice of the low-hanging: the profile of the consumption by the shift;

The aggregates of the book: the electrical savings of the programs extend frequently to 10-20% of the electric bill from the “banal” items (the leaks, the throttling, the classification) rather than the replacement of the mills: the rule of the energy audit: the smallest of the fixes first: the institutional: the book carries the detailed checklist of the auxiliaries.

6. The Heat Recovery of the Waste: The WHR and the District Applications

The energy frontier chapter: the recovery of the waste heat from the clinker process:

• The waste heat power technologies: the steam Rankine from the cooler gas, the alternative of the ORC for the lower temperature: the combined installations: the modern projects recover 10-25 kWh/t of the clinker into electricity: the book: the economics: the kWh cost of the electricity, the operation, the amortization;
• The cascade to the process: the heat of the exit gas dries the raw meal and the coal, the WHR of the cement mills: the multi-purpose: the plant engineering: the district heating of the neighbouring towns (the cases of the Scandinavian and the European plants): the heat pump of the kiln’s steam to the city network: the measured in the tens of MW;
• The alternative fuels: the energy of the waste: a “renewable thermal” under the carbon accounting: the book: the EU plants with the 50%+ thermal substitution rate: the kiln, the equipment, the flue: see the separate chapter below;

The book places the recovery in the economics: the WHR plants show the progress in the higher electricity markets: the recovery of the “low heat” for the drying of the silicate: for the regional use: the multipurpose the plant to the community: the papers of the volume show the cement plant as a full partner of the city’s energy mix, and the payback of the integrated project beats the payback of the standalone generator.

7. The Alternative Fuels: The Combustion of the Waste in the Kiln

The chapter of the alternative fuels in the European industry: the growth of the use of the industrial waste as the kiln fuel:

• The energy hierarchy: the waste hierarchy (the prevent, reuse, recycle, recover) applied to the kiln: when the waste cannot be recycled materially, the kiln recovers the chemical energy: the book: the term “co-processing”: the concept of the assembly of the burning;
• The fuels of the portfolio: the waste tires (the steel returns to the kiln; the scrap), the plastics, the auto shredder residue, the sewage sludge, the skeleton, the paper wastes, the solvents: the chemical energy and the chlorine content, the compliance of the feeding points: the book details the handling and the storage of each family;
• The thermal substitution rate (TSR): the percentage of the heat from the alternative: the benchmark: the EU leading plants between 50 and 90%, the world average in the teens: the drivers: the price, the landfill targets, the CO2: the book: the “quality” of the alternative: the process must not degrade the product: the ash of the fuel enters the clinker: the corrections of the raw mix:
• The environmental permitting: the combustion of the waste in the kiln: in the EU the Waste Incineration rules apply: the retention time of the 2 seconds at 850 C+ (in parts 1100 C) in the burner zone: the monitoring (the CO, the PCDD) and the QA/QC of the fuel: the book: the permitting: the effect of the heavy metals on the clinker:

The alternative fuel chapter closes with the economics: the energy of the residual waste replaces the coal: the two for one: the thermal part and the waste disposal part: the book: the plants that co-process: the kiln acts as the safest incinerator and the clinker as the sponge of the ash: the economics of the gate fee and the avoided energy: the “waste-to-clinker” is the biggest energy saving of the modern European operation.

8. The Process Control and the Automation for the Energy

The control theory: the energy of the process: the level of the automation as the energy theme of the book:

• The stability of the kiln: the ox noise stops the energy: the excursions of the operation: the stable kiln control: less coal, less lining wear, less refuse: the controller: the oxygen at 1-3%: the minimum oxygen without the CO: the draft balance:
• The QC of the raw mix and the control of the feed: the X-ray of the raw mix, the online analyzer (PGNAA), the stable LSF: the well-blended kiln feed: the saving: the fuel and the wear: the slides: the standard deviation of the clinker: the book: the quality statistics and the return of the control loops;
• The grinding control: the recirculation loops, the amplitude of the mill (the acoustic, the power), the separator speed: the online particle size: the 1-5% power: the quality: the chapter: the process control sensors and the DCS;
• The energy management systems (EMS): the ISO 50001 systems: the monthly reporting of the specific energy: the annual baseline: the sub-metering: the dashboard: the older book written in the 1990s had not the ISO, but today’s reader integrates the principles in the EMS: the book’s report format: the managers, the cost of the lack, the audits:

The practice of the chapter: the most accessible of the savings: the loops, the control, the energy-efficiency of the DCS: the book: the continuous measurement: the experts: the “the plant: the performance”: the level of the automation of the plant determines the level of the achievable savings, and the book’s case plants show the stable kilns saving the 3-5% just through the control.

9. The Energy of the Finish and the Cement: The Dispatch and the Logistics

The book reaches the finishing side: the cement, the storage, the dispatch: the energy of the product not the clinker:

• The cement mill optimization: the fineness of the cement vs the strength demand: the 28-day requirement: the specification: the inter-grinding: the grindability: the energy to the market of the cement and not the clinker alone: with the mineral additions, the mill efficiency improves: the one megajoule saved in the finish is the one megajoule saved in the market;
• The packing and the dispatch: the filling of the bags, the truck scales, the ship and the rail loading: the dispatch time: the truck scale compliance: the electricity of the packing lines: the small but the always operating: the shift reports:
• The storage and the cement: the cement aging, the aeration of the silos, the preservation: the maintenance: the electrical: the temperature of the cement: the energy of the cement in the transport (the truck efficiency, the rail, the ports): the book: the “gray energy” of the dispatch: the formulation horizon:

The finishing section of the book says consistently: “the energy does not stop at the clinker”: the energy of the grinding, the finishing, the packing and the transport together decide the cost of the product in the market: the case studies of the winners dispatch efficiently: the energy balance completes with the cement in the customer’s silo.

10. The Energy Cases: The Case Studies of the Book

The book’s case studies: the ten national and company experiences: the savings: the measured numbers of the reference volume:

• Case A: the dry conversion of the wet plant: the plant of 700 tpd wet converted to 1,500 tpd dry with the suspension preheater: the specific heat from 5.9 to 3.3 GJ/t (44% decline): the CAPEX of the project ~35-45% of a new line: the fuel saved in less than 6 years: the sample of the “modernization is the energy strategy”:
• Case B: the precalciner and the margin: the 2,500 tpd plant added the calciner and the 5-6 cyclone stages: the line reaches 4,000 tpd: the specific heat from 3.7 to 3.2: the production gained going with the lower energy;
• Case C: the audit of the medium plant: the audit found 12% of the savings: the 60% from the fans (the VFDs, the leaks), 25% from the mills (the media, the separator class), 15% from the services (the compressed air and the lighting): the total 9 kWh/t of the cement: the payback 0.5-2 years: the least capital;
• Case D: the high TSR plant: the European plant with the 70% of the heat from the alternative fuels: the fossil ~30%: the energy cost of the cement fell to the level of the gate fees: the dual revenue model of the alternative fuels:

The case studies show a pattern: the repair of the day is the success of the discipline: the energy of the industry parks the measured: the book is the evidence: the volume’s conclusions (the EC program) estimate the saving potential of the European cement industry: the industry-wide 20-30% of the energy, achieved in the 10 years of the conversions and the audit cycles: the numbers printed in the document remain the benchmark for the audits of today.

11. The Obstacles to the Efficiency: The Table of the Hurdles

The honest chapter of the obstacles: why the industry did not adopt all the energy measures: the behavioral and the institutional:

• The capital availability: the benefit needs the capital: the different plants have the different means: the amortization: the capital of the small plants is limited: the public policy instruments (the grants of the EC program, the fiscal) are part of the case:
• The behavior of the energy: the performance: the manager, the benchmark, the reputation: the waste: the company: the losses of the habit: the experience: the “the equipment saves”: the organizational culture: the motivation: the audits: the ownership of the energy budget:
• The conflict of the process: the energy saves against the product and the raw quality: the kiln: the decision: the “I’m not going to install the VFD because the electrician is the expert”: the market failure: the lack of the real-time data: the constraints of the process on the energy projects:
• The knowledge gap: the plants of the country: the trained energy teams: the aging staff: the EC supported the energy centers and the industry associations: the book: the training: the national energy agencies of the EC: the Finland and the Italy cases document the model:

The chapter closes with the economic truth: “Energy saving is not a project, it is a management practice”: the meter, the audit, the conversion, the control: the four tools of the chapter: without the four, the energy stays on the floor of the industry: with them, the saving becomes the profit: well is the message of the whole volume: the transform of the energy efficiency is a discipline of the management, not of the physics alone.

12. The Frequently Asked Questions

Where do the biggest energy losses of the cement plant settle?

The kiln gas to the stack (the dry plant 15-30%), the shell and the cooler exhaust (each 5-15%), the water evaporation of the process: and the electricity of the grinding: the ranking: the audit finds the fuel first, the mills and the fans second: the book calibrates the weight of each flow: each percentage of the improvement of the kiln heat is the first saving of the plant.

Does the dry process always repay the investment?

The modern dry: 3.0-3.6 GJ/t, the wet: 5.5-6.5: the dry requires the right raw material (the moisture, the chemistry), the capital of the conversion: the paying: 5-8 years on the fuel: the case: the permits: the numbers in the book: the full table of the processes: the “wet” remains for the special cases (the powdery materials and the geothermal plants): the chapter details the exceptions.

The electric or the thermal energy of the plant: which is the biggest?

In the money: the fuel (60-70% of the energy bill) exceeds the power (30-40%): in the CO2 the fuel dominates even more: but the electric has the simpler savings (the leaks, the fans, the compressors) with the fastest payback of 1-2 years: the book balances both: the business and the carbon of the plant, card: the diagnosis with the sub-metering.

Does the energy efficiency prepare the plant for the waste heat recovery?

Directly: the WHR depends on the temperature and the flow of the exit gases: the efficient plant with the good recovery reaches the 25-30 kWh/t of the WHR project: the design: the cascade: the book: the “waste” heat of the plant serves the raw mill, the district, the power: the efficient plant integrates the maximum: the heat that the plant does not produce it does not need to recover.

Was the “waste” ash of the alternative fuel really clean for the cement plant?

The chapter of the book: the permitted fuels (the waste incineration legislation: the chlorine limit, the low temperature) and the chemistry: the ash of the fuel (P, Cl, SO3) modifies the clinker of the cement: the cement quality must be maintained: the engineering of the raw mix corrections: the cement industry of the EU operates at the 50-70% TSR in the optimized plants: the book: no rule, the co-processing is the disciplined process technology: the line is the correct answer.

How does the energy saving relate to the CO2 reduction of the cement?

The CO2 of the cement (~0.7-0.9 t/t of the CEM I, including the calcination) comes from the fuel for about 35-40%: the efficiency reduces that share proportionally: the rest of the CO2 is the inherent limestone decarbonation: the book: the cascade: the efficiency first, the alternative fuels second, the clinker factor third, and the capture in the future: the energy savings of the industry have already cut the CO2 per tonne by a fifth since the 1990s.

13. Conclusion

Energy Efficiency in the Cement Industry: the book of the practice of the energy: the balance, the audit, the ladder of the processes, the recovery, the fans and the compressors, the control: the energy accounting of the plant: the numerical evidence of the case studies: the energy of the European cement industry over the decades of the modernization: the reader closes the volume with a complete method: the meters, the sub-committee, the masses of the energy: this is the way the energy efficiency is done, and the book shows it.

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