Heat Balance Cement Industry Excel: Complete Guide & Downloa

The heat balance of the cement industry is the thermal accounting of the kiln line: every kilocalorie that enters the system in the fuel, the raw meal, the combustion air and the feed must leave it in the clinker, the exhaust gas, the dust, the cooler air, the radiation and the convection losses, and every percentage point of imbalance is a percentage of the fuel money that leaks through the shell. The Excel sheet of this article (the heat balance workbook prepared by Er. Raza Hussaini, an old and proven tool of the cement engineers) turns that accounting into a structured spreadsheet: the input cells for the feed, the fuel, the temperatures and the gas analysis; the calculation rows for each heat term; the automatic summation of the input side and the output side; and the closing error that tells the engineer whether the measurements are honest.

The plant engineer runs the heat balance once a month, after every major refractory repair, and before and after every fuel switch, because the balance is the only document that shows where the thermal energy of the process actually goes. The Complete Cement Technical Package (931 files: the handbooks, the training courses, the Excel tools and the presentations, $249.99 one-time, instant download through the secure PayPal payment) delivers this heat balance workbook together with the full library of the process calculation tools, and this article walks the reader through the sheet: the inputs, the formulas, the worked numbers, the interpretation and the action that follows the balance.

1. The Purpose of the Heat Balance in the Cement Plant

The heat balance is the first law of thermodynamics written in the language of the production line: energy is neither created nor destroyed, so the heat entering the kiln system must equal the heat leaving it plus the heat accumulated in the equipment. In the cement industry the balance is expressed per kilogram of clinker, in kilocalories per kilogram (kcal/kg) or megajoules per tonne (MJ/t), and the reference base is the burning of 1 kg of clinker at the stable operation of the line.

• The process control value: the balance quantifies the specific heat consumption of the kiln: the modern five-stage preheater precalciner lines operate at 700–800 kcal/kg of clinker, the four-stage lines at 750–850, the wet process at 1,300–1,600 and the dry long kilns without preheater at 950–1,200: the plant compares its number with the benchmark of its technology and finds the gap;
• The loss identification: the balance splits the total into the terms: the exhaust gas, the cooler losses, the shell radiation, the dust: the engineer sees at once whether the biggest thief is the preheater gas temperature or the kiln shell: the ranking of the losses drives the priority of the projects;
• The project justification: every energy saving investment (the new preheater stage, the kiln shell insulation, the waste heat recovery boiler, the cooler optimization) is justified by the numbers of the balance: the before and the after balances of the project quantify the saving that the management approves;
• The measurement audit: the closing error of the balance reveals the quality of the instruments: if the inputs exceed the outputs by more than five percent, the flow meters, the temperature sensors or the gas analyzers are wrong: the balance is the audit of the instrumentation as much as the audit of the process;
• The baseline for the energy management: the ISO 50001 energy management systems of the plants are built on the periodic heat balances: the energy baseline, the performance indicators and the energy reviews all feed from the same numbers that the balance sheet produces.

The heat balance is therefore not an academic exercise but the monthly management report of the thermal performance: the finance of the kiln, computed in kilocalories. The Excel sheet of Er. Raza Hussaini standardizes the computation so that the same format serves the engineer on the day shift and the auditor from the head office.

2. The Structure of the Heat Balance Spreadsheet

The workbook of the heat balance is organized in the logical order of the computation: the data entry section, the calculation section, the summary section and the comparison section. The engineer works on the yellow input cells and reads the results in the red and the bold output cells, the classic discipline of the engineering spreadsheets.

• The data entry sheet: the production data (the kiln feed in tons per hour, the clinker production in tons per day, the hours of operation), the fuel data (the fuel consumption, the net calorific value, the ultimate analysis, the ash content), the temperature data (the preheater exit gas, the clinker at the cooler exit, the kiln shell, the ambient), and the gas analysis data (the O2, the CO2 and the CO at the preheater exit and at the kiln inlet);
• The calculation sheet: the working rows of the heat input and the heat output terms, each row with its formula, its units and its reference, so that the engineer can audit every number of the balance back to the measurement;
• The summary sheet: the total heat input, the total heat output, the closing error and the specific heat consumption, presented in the table that goes to the management report;
• The comparison sheet: the previous balances stored side by side with the current one: the trend of the specific heat consumption, the trend of each loss term, and the deviation of the current balance from the baseline: the monthly story of the thermal performance.

The structure of the sheet follows the standard methodology of the cement process engineering: the same term structure that the industry handbooks (Peray, Duda, the Lafarge training modules) present, so that the results of the sheet are comparable with the literature values and with the balances of the other plants in the group.

3. The Input Data: Feed, Fuel and the Temperatures

The quality of the heat balance is decided at the data entry stage, and the sheet organizes the inputs in the order of the process. The first group is the material flow data: the kiln feed in tons per hour, measured on the raw meal weighing system of the kiln feed, and the clinker production, which in the plants without the clinker weigh-belt is derived from the feed through the clinker factor, exactly as the sheet of this package does.

• The kiln feed: the tons per hour of the raw meal entering the preheater: the measurement of the day with the stable operation, averaged over the balance period of 24 to 72 hours to smooth the process fluctuations;
• The clinker factor: the ratio of the raw meal to the clinker: the typical values of 1.50 to 1.70 for the ordinary Portland cement mixes, computed from the loss on ignition of the raw meal: the clinker production equals the feed divided by the factor;
• The fuel flow and the calorific value: the tons per hour of the coal, the petcoke, the gas or the alternative fuel, with the net calorific value from the laboratory: the fuel is the dominant input term of the balance, typically 85–95 percent of the total heat input, so its accuracy decides the accuracy of everything else;
• The temperatures: the preheater exit gas temperature, the kiln shell temperatures (the averaged profile), the clinker temperature at the cooler exit, the secondary air temperature, the ambient temperature: each feeds its term of the balance;
• The gas analysis: the O2, the CO2 and the CO at the preheater exit: the gas analysis gives the gas volume flow through the nitrogen balance, the standard method of the industry: the heat carried by the exhaust gas is computed from the analyzed composition and the measured temperature.

The sheet reminds the engineer of the golden rule of the balance: the numbers must all belong to the same period. The feed of the Monday, the gas analysis of the Tuesday and the fuel of the Wednesday do not make a balance; they make a noise. The discipline of the simultaneous measurement campaign is the prerequisite of the meaningful balance, and the sheet documents the date and the hour of each data set so that the audit trail remains complete.

4. The Clinker Production from the Feed: The Factor of the Sheet

The classic step of the sheet of Er. Raza Hussaini is the derivation of the clinker production from the kiln feed through the clinker factor, the method used by the plants that do not weigh the clinker directly. The actual workbook of the package demonstrates the calculation with the concrete numbers: the kiln feed of 500 tons per hour and the clinker factor of 1.63, and the sheet returns the clinker production of 7,361.96 tons per day.

The arithmetic of the example: the feed of 500 t/h over the 24 hours of the day gives the daily feed of 12,000 tons of raw meal; the daily feed divided by the clinker factor of 1.63 gives the clinker production of 12,000 / 1.63 = 7,361.96 tons per day, which is exactly the number of the sheet. The clinker factor itself comes from the loss on ignition of the raw meal: the factor equals 100 / (100 − LOI), and for the raw meal with the LOI of 35.5 percent the factor is 100 / 64.5 = 1.55, while the raw meal with the LOI of 38.7 percent gives the factor of 100 / 61.3 = 1.63, the value of the example.

• The LOI method: the clinker factor from the loss on ignition of the raw meal: the standard method of the industry, accurate when the meal chemistry is stable;
• The dust correction: the raw meal dust returned to the kiln and the dust lost in the exhaust modify the simple ratio, and the refined balances include the dust return flows;
• The direct measurement: the plants with the clinker weighers use the measured clinker directly, and the factor then serves as the cross-check of the two measurements;
• The daily reconciliation: the sheet compares the derived production with the silo inventories and the dispatched cement, and the difference of more than one percent triggers the check of the feed weigh-feeders.

The feed and the factor are the basis of the whole balance because every specific term of the balance (the kilocalories per kilogram of clinker) is the absolute term divided by the clinker production: a wrong factor spreads through the entire sheet. The example of the file shows the correct handling of the step, and the engineer copies the method for the own data.

5. The Heat Input Terms of the Balance

The input side of the heat balance collects everything that brings heat into the kiln system, and the sheet lists the terms in the fixed order that the industry uses:

• The heat of the fuel combustion (Q1): the fuel flow multiplied by the net calorific value: for the coal with the net calorific value of 22 MJ/kg (5,260 kcal/kg) and the flow of 40 t/h, the term is 40,000 kg/h × 5,260 kcal/kg = 210.4 million kcal/h: the dominant term of the input side, 85–95 percent of the total;
• The sensible heat of the fuel (Q2): the heat that the fuel itself carries at its feeding temperature: the fuel mass multiplied by its specific heat (0.25–0.30 kcal/kg°C for the coal) and the temperature difference to the reference: for the coal at 60°C with the reference of 25°C, the term is 40,000 × 0.27 × 35 = 378,000 kcal/h, a small term but a real one;
• The sensible heat of the raw meal (Q3): the raw meal enters the preheater at the ambient temperature in the modern plants, so the term is small, but in the plants with the hot gas drying or the preheating the term matters;
• The sensible heat of the primary and the combustion air (Q4): the primary air is cold, but the secondary air from the cooler is hot and its heat is counted: in the standard methodology the secondary air heat is returned to the system through the cooler, and the input side counts the primary air only, which is small;
• The heat of the combustion reactions other than the fuel (Q5): the heat of the oxidation of the sulfides, the organic matter of the raw meal and the combustion of the CO: the terms are small but they explain the differences between the plants with the pyrite-rich raw materials.

The input side of the balance is deliberately simple because the fuel dominates it: the art of the balance is on the output side, where the same amount of heat splits into the ten different streams and the engineer must chase every one of them.

6. The Heat Output Terms of the Balance

The output side of the heat balance is where the thermal personality of the kiln line shows itself, and the sheet lists the terms in the standard order:

• The theoretical heat of the clinker formation (Q6): the endothermic heat of the chemical reactions that convert the raw meal into the clinker: 400–430 kcal/kg of clinker for the ordinary mixes, the single largest unavoidable term of the process: the thermodynamic minimum that no optimization can reduce;
• The sensible heat of the clinker (Q7): the clinker leaves the kiln at 1,350–1,450°C and the cooler recovers most of its heat: the clinker at the cooler exit at 100–150°C still carries 20–35 kcal/kg, and the number depends on the cooler performance;
• The sensible heat of the preheater exhaust gas (Q8): the gas leaves the top of the preheater at 280–380°C in the modern five-stage lines and carries 120–160 kcal/kg of clinker: the largest controllable loss of the modern plant and the target of the waste heat recovery;
• The heat of the dust (Q9): the dust leaves with the exhaust gas and the bypass, and the loss depends on the dust quantity and its temperature: 5–15 kcal/kg in the typical plants;
• The heat of the cooling air of the cooler (Q10): the cooler exhaust air leaves at 250–400°C with the significant heat: the excess cooling air is the second largest controllable loss;
• The radiation and the convection losses of the shell (Q11): the heat lost through the kiln shell, the preheater towers, the ducts and the hoods: 30–60 kcal/kg depending on the refractory condition, the shell temperatures and the ambient conditions;
• The unaccounted losses (Q12): the difference that closes the balance: the false air, the measurement errors, the incomplete combustion: in the good balances the term stays below 3 percent of the input.

The output table of the sheet shows each term in the kilocalories per kilogram of clinker and in the percent of the total input, and the two views together give the complete picture: the absolute numbers for the engineering, the percentages for the management presentation.

7. The Theoretical Heat of the Clinker Formation

The theoretical heat of the clinker formation is the thermodynamic anchor of the balance, and the sheet computes it by the standard method of the industry: the sum of the endothermic reactions minus the heat of the crystallization of the clinker phases. The composition of the clinker decides the number: the ordinary Portland clinker requires about 420 kcal/kg, the white clinker and the mixes with the high C3S a little more, and the reference decomposition of the main steps is:

• The de-carbonation of the limestone (the calcination): the limestone decomposes to the lime and the CO2, absorbing about 760 kcal per kg of the CO2 released, or roughly 320 kcal per kg of the clinker for the typical raw meal: the dominant endothermic step of the process;
• The de-hydroxylation of the clay minerals: the kaolinite and the illite lose their combined water, absorbing about 30–40 kcal/kg of the clinker;
• The formation of the clinker phases: the exothermic reactions of the lime with the silica, the alumina and the iron oxide to form the alite, the belite, the aluminate and the ferrite release about 70–80 kcal/kg in the modern interpretation, and the crystallization of the melt another 20–30 kcal/kg;
• The net value: the difference of the endothermic and the exothermic terms gives the 400–430 kcal/kg of the theoretical heat: the industry usually quotes 420 kcal/kg (1,760 kJ/kg) as the reference value of the ordinary clinker.

The theoretical heat is the floor under the specific heat consumption: no kiln of the world can fire below it, and the difference between the actual consumption (700–800 kcal/kg) and the theoretical 420 kcal/kg is the loss that the engineer fights: the 280–380 kcal/kg of the gap are exactly the terms of the output side, and the balance shows where each kilocalorie of the gap sits.

8. The Worked Example of the Heat Balance

Follow the sheet through the complete worked example, the same structure that the workbook of the package demonstrates. The line: the five-stage precalciner kiln at 500 t/h of the kiln feed, the clinker factor of 1.63, the clinker production of 7,361.96 t/d (306.7 t/h), the coal at 22 MJ/kg (5,260 kcal/kg) with the flow of 38.4 t/h, the preheater exit gas at 320°C, the clinker at the cooler exit at 120°C, and the kiln shell at the average of 250°C against the ambient of 25°C.

Term	Value (kcal/kg clinker)	Percent of input
Fuel combustion heat (input)	658.6	97.6
Sensible heats of fuel, meal, air (input)	16.4	2.4
Total heat input	675.0	100.0
Theoretical heat of clinker formation	420.0	62.2
Sensible heat of clinker at cooler exit	18.0	2.7
Sensible heat of preheater exhaust gas	140.0	20.7
Cooler exhaust air loss	60.0	8.9
Shell radiation and convection	45.0	6.7
Dust and minor losses	12.0	1.8
Total heat output	695.0	—
Closing error	+20.0 (+3.0%)	—

• The fuel term: 38,400 kg/h × 5,260 kcal/kg = 201.98 million kcal/h; divided by the clinker rate of 306,700 kg/h gives 658.6 kcal/kg of clinker, and with the sensible heats of the fuel, the air and the small terms the total input closes at about 675 kcal/kg;
• The theoretical heat: 420 kcal/kg (128.8 million kcal/h, the 62.5 percent of the input in this example);
• The clinker sensible heat: 306,700 × 0.19 kcal/kg°C × (120 − 25) = 5.53 million kcal/h, the 18 kcal/kg;
• The preheater exhaust gas: the gas flow from the nitrogen balance of about 1.3 million Nm3/h at 320°C carries about 140 kcal/kg of clinker: the largest loss of the modern line;
• The cooler exhaust: the excess air at 350°C carries about 60 kcal/kg;
• The shell losses: the kiln shell, the preheater and the hoods radiate about 45 kcal/kg;
• The dust and the minor terms: about 12 kcal/kg;
• The sum of the outputs: 420 + 18 + 140 + 60 + 45 + 12 = 695 kcal/kg against the input of 675 kcal/kg: the closing error of about 3 percent, the acceptable range of the industry balances, absorbed by the unaccounted losses and the measurement uncertainty.

The example shows the pattern of the modern precalciner line: the exhaust gas, the cooler and the shell take almost the whole gap between the theoretical heat and the actual consumption, and every improvement project of the plant attacks one of these three terms.

9. The Thermal Efficiency and the Interpretation

The summary section of the sheet computes the thermal efficiency of the system as the ratio of the theoretical heat of the clinker formation to the total heat input, and the number becomes the headline of the energy report:

• The thermal efficiency: the theoretical heat of 420 kcal/kg divided by the input of 675 kcal/kg gives 62.2 percent: the modern precalciner plants operate in the 55–65 percent band, the four-stage lines at 50–58, and the wet process lines at 28–32 percent: the technology comparison table of the sheet positions the plant;
• The specific heat consumption: the total input per kg of clinker: the single most quoted number of the cement industry: the sheet compares the actual value with the design value of the line and with the industry benchmark of the same kiln type;
• The trend: the monthly balances show the seasonal movement of the consumption (the warmer ambient of the summer reduces the shell losses), the effect of the refractory age, and the effect of the fuel changes: the deviations beyond the normal band trigger the investigation;
• The action priority: the sheet ranks the controllable losses and the engineer attacks the largest one first: the standard rule of the energy management: the largest loss is always the best project.

The interpretation is the purpose of the balance: the numbers without the ranking and the trend are the archival data, and the numbers with the ranking and the trend are the energy policy of the plant. The sheet of the package delivers both, in the single summary page that the production manager reads at the monthly meeting.

10. The Exhaust Gas and the Waste Heat

The preheater exhaust gas is the largest controllable loss of the modern kiln and the target of the biggest investments of the industry, and the balance quantifies it with precision. The gas volume is derived from the oxygen and the nitrogen analysis by the nitrogen balance method: the nitrogen enters with the combustion air and leaves with the exhaust gas, and the measured O2, CO2 and CO fix the air flow and the gas volume at the measured temperature.

• The gas flow: the flue gas volume per kg of clinker, the 1.35–1.55 Nm3/kg of the dry process lines, composed of the CO2 of the calcination (about 0.35 Nm3/kg), the CO2 and the H2O of the combustion, and the excess air;
• The gas temperature: the 280–380°C of the five-stage lines, the 350–420 of the four-stage, the 550–700 of the two-stage, and the 900 of the long dry kilns: the temperature multiplied by the gas volume and the specific heat (0.31–0.33 kcal/Nm3°C) gives the loss term;
• The waste heat recovery: the balance of the modern plants feeds the design of the waste heat recovery boilers that generate the 6–10 MW of the electricity from the 320°C gas of the 5,000–7,000 t/d lines: the preheater exit gas and the cooler exhaust air are the two recovery sources;
• The gas analysis corrections: the CO in the exhaust gas represents the chemical loss of the incomplete combustion (about 3,020 kcal/kg of the CO at the complete combustion to CO2) and the balance flags any CO above the 0.1 percent as the immediate fire problem.

The exhaust gas term of the sheet therefore serves the two purposes: the energy accounting and the design basis of the recovery projects. The engineers of the plants with the waste heat recovery run the balance quarterly and compare the predicted and the actual steam production of the boilers, keeping the two sides of the energy story consistent.

11. The Shell Losses and the Radiation Term

The shell losses of the kiln and the preheater are computed by the sheet from the measured shell temperatures and the standard heat transfer correlations, and the term is the one that the maintenance department can influence directly through the refractory policy:

• The radiation loss: the Stefan-Boltzmann term: q_rad = ε · σ · (T_shell^4 − T_ambient^4), with the emissivity of the painted steel shell of about 0.85–0.95, the Stefan-Boltzmann constant of 4.88 × 10^-8 kcal/m2 h K4, and the absolute temperatures: at the shell of 280°C (553 K) against the ambient of 298 K, the radiation flux is about 0.85 × 4.88 × 10^-8 × (553^4 − 298^4) = 3,680 kcal/m2 h;
• The convection loss: q_conv = h · (T_shell − T_ambient), with the convective coefficient h of 8–14 kcal/m2 h °C depending on the wind and the kiln rotation: at the 280°C shell with the coefficient of 12, the convection flux is 12 × 255 = 3,060 kcal/m2 h;
• The combined loss: the two terms together give the specific surface loss of the shell: the 6,700–6,900 kcal/m2 h at the 280°C surface, and the industry benchmark of the specific shell loss of 60–110 kcal/m2 h per degree of the shell temperature above the ambient;
• The kiln shell total: the kiln of 4.4 m diameter and 60 m length has the shell area of π × 4.4 × 60 = 829 m2, and at the average temperature of 250°C the total shell loss is in the range of the 3.5–4.5 million kcal/h, the 12–15 kcal/kg of clinker for the 306.7 t/h line of the example;
• The refractory condition: the shell temperature profile tells the story of the brick: the burning zone at 180–250°C with the healthy coating, the 300–380°C zones with the thin coating or the brick damage, and the hot spots above 400°C that force the kiln stop: the balance sheet converts the IR scanner data into the kilocalories.

The shell term of the sheet is the bridge between the maintenance and the energy departments: the refractories budget is an energy budget, and the balance gives it the number that the management understands: the thermal losses of the shell, in the kilocalories per kilogram and in the money per month.

12. The False Air and the Measurement Errors

The unaccounted term of the balance is rarely the pure measurement noise: the false air leaking into the preheater, the kiln inlet and the cooler pulls the balance apart, and the experienced engineer reads the closing error of the sheet as the first diagnostic of the leakage:

• The false air at the preheater: the air leaking through the flanges, the doors and the sampling points of the tower increases the gas volume, cools the gas, raises the O2 of the exit gas and adds the sensible heat to the exhaust term: the balance of the leaky line shows the inflated exhaust loss;
• The false air at the kiln inlet: the air entering at the kiln inlet reduces the secondary air temperature seen by the flame, cools the burning zone and raises the fuel consumption: the effect shows in the balance as the increased fuel term with the unchanged production;
• The false air at the cooler: the leakage in the cooler housing increases the cooler exhaust flow and its loss term: the balancing of the cooler air streams (the cooling air, the secondary air, the tertiary air and the exhaust) exposes the leak;
• The measurement errors: the drift of the fuel weigher, the biased thermocouple, the incorrect gas calibration: the sheet keeps the record of the instrumentation so the engineer distinguishes the process problem from the measurement problem: the rule of the industry: the balance error above 5 percent is a measurement campaign to be redone, not a report to be signed.

The false air chapter turns the heat balance into the airtightness audit of the line: the same numbers that the energy report shows are the input of the leakage repair plan, and the plants track the closing error of the balance as the KPI of the maintenance quality.

13. The Excel Sheet in Practice: The Columns and the Cells

The practical value of the sheet of the package is the working discipline of the calculation: the engineer enters the day’s data and the workbook returns the complete balance with the formulas that stay auditable. The layout of the sheet follows the industry convention:

• The input block: the yellow cells of the production, the fuel, the temperatures and the gas analysis, each cell labelled with the unit and the source of the data;
• The calculation block: the working rows of the terms with the visible formulas: the engineer clicks the cell and sees exactly how the number was computed, and the wrong formula is caught in the review before the wrong decision;
• The unit discipline: the sheet works in the kilocalories per hour in the working rows and converts to the kilocalories per kilogram of clinker in the summary: the conversion factor is the clinker production in kg/h, the cell that connects the two views;
• The verification rows: the internal checks of the sheet: the sum of the outputs against the sum of the inputs, the percent error, and the flag cells that color the result red when the error exceeds the tolerance of the plant;
• The documentation rows: the date of the measurement campaign, the operator, the condition of the line (the stable operation or the start-up), and the notes: the balance that cannot be reconstructed from its notes is the balance that cannot be defended in the audit.

The sheet is the deliverable that the engineer keeps and extends: the plants adapt the workbook with the extra rows for the alternative fuels, the bypass and the WHR boilers, and the format of the package serves as the skeleton of the plant-specific energy management file. The engineering of the heat balance is mostly the engineering of the data and the formulas, and the Excel sheet makes both transparent.

14. The Heat Balance of the Precalciner Kilns

The modern precalciner lines require the heat balance in the extended form that splits the fuel between the kiln and the calciner, and the sheet handles the split through the input fields of the two fuel flows:

• The fuel split: the calciner typically fires 55–65 percent of the total fuel and the main burner the rest: the balance enters the two flows separately, with the calciner fuel at the lower temperature of the precalciner and the main fuel at the flame of the kiln;
• The calcination split: the precalciner performs 90–95 percent of the calcination, and the kiln completes the rest with the low degree of the calcination burden on the burning zone: the balance of the calciner section and the balance of the kiln section are computed separately and summed in the total;
• The tertiary air: the hot air from the cooler diverted to the calciner carries the heat into the preheater tower, and the balance counts the tertiary air flow and its temperature among the inputs of the calciner section;
• The NOx effect: the staged combustion of the calciner changes the heat release pattern and the exhaust gas composition, and the balance of the precalciner line shows the lower specific consumption of 700–760 kcal/kg against the 780–850 of the kiln-only dry lines;
• The bypass: the lines with the high alkali and the chloride loads run the kiln gas bypass that removes the 5–15 percent of the kiln gas and their heat: the sheet includes the bypass row among the losses.

The precalciner balance is the balance of the modern industry: the two fire points, the tertiary air and the staged combustion give the engineer the more complex sheet but also the more powerful tool, and the workbook of the package demonstrates the extended format with the same clarity as the simple kiln balance.

15. The Frequent Findings of the Balance Campaigns

The years of the heat balance practice have produced the familiar list of the findings that the sheet exposes, and the experienced engineer checks the usual suspects first:

• The high exhaust gas temperature: the fouling of the preheater cyclones, the overfeeding of the line, the poor heat exchange: the recovery projects and the cleaning campaigns follow the balance finding;
• The high shell temperatures: the refractory age, the missing coating, the brick damage: the shell scan of the balance campaign becomes the refractory repair plan;
• The high cooler losses: the over-aeration of the cooler, the worn grates, the poor clinker distribution: the cooler fan audit and the grate adjustment follow;
• The high specific consumption without the visible loss: the false air, the measurement drift: the closing error of the sheet points to the instrumentation campaign;
• The seasonal swing: the 10–20 kcal/kg between the winter and the summer balances from the ambient effects: the baseline of the energy management adjusts the targets by the season, and the sheet stores the seasonal reference.

The findings chapter closes the loop of the practice: the balance is run, the findings are ranked, the projects are implemented, and the next balance measures the result: the cycle of the continuous improvement that the modern energy management systems institutionalize, with the heat balance sheet of the package as the standing instrument of the cycle.

16. Frequently Asked Questions

How often should the heat balance be performed?

The monthly balance is the practice of the well-run plants, with the special balances after every significant change: the new fuel, the new refractory, the cooler modification, the preheater stage addition and the start-up after the long stop. The balance is also the standing requirement of the energy audits, the ISO 50001 reviews and the corporate energy reporting, and the sheet of the package makes the repeated balance a thirty-minute job instead of the day-long manual calculation.

What is a good closing error for the heat balance?

The closing error below 3 percent of the total input is the industry-accepted quality of the balance, and the balances with the error above 5 percent are treated as the measurement campaign to be redone rather than the result to be reported. The persistent positive error (the inputs exceeding the outputs) usually indicates the under-measured fuel or the over-stated production, and the persistent negative error the false air or the over-measured temperatures.

Why is the heat balance expressed per kilogram of clinker?

The per-kilogram basis makes the comparison independent of the line size: the engineer compares the 3,000 t/d line with the 10,000 t/d line, the month of the high production with the month of the low production, and the plant of the group with the sister plant, always on the same basis. The absolute kilocalories per hour are the working numbers of the operations, and the per-kilogram numbers are the language of the management and the benchmarking.

What is the difference between the theoretical and the actual heat consumption?

The theoretical heat of the clinker formation is the thermodynamic minimum of about 420 kcal/kg: the energy of the chemical reactions themselves. The actual consumption adds all the losses of the real process: the exhaust gas, the clinker, the cooler air, the shell, the dust and the unaccounted terms, and the difference of the two (the 250–400 kcal/kg) is exactly the sum of the loss terms of the output side. The heat balance is the instrument that splits the difference into the accountable streams, and the sheet of the package does the splitting in the format of the industry.

Can the heat balance be computed from the existing plant instruments alone?

Yes, for the routine monthly balance the existing instruments suffice when they are calibrated: the feed weighers, the fuel weigher, the preheater exit temperature, the gas analyzers and the shell temperature data of the IR scanner provide the complete input set. The special balance campaigns add the temporary instruments (the pitot tubes, the calibrated analyzers, the extra thermocouples) to reduce the closing error below 2 percent, and the sheet accepts the inputs of both the routine and the campaign measurement levels.

Does the package include the ready Excel heat balance workbook?

Yes: the Complete Cement Technical Package (931 files) contains the original heat balance Excel sheet by Er. Raza Hussaini together with the full library of the calculation tools, the process handbooks and the training materials, and the buyer downloads the working workbook with the formulas intact, enters the own data and reads the own balance in the format of the industry.

17. Conclusion

The heat balance of the cement industry is the thermal audit of the kiln line, and the Excel sheet of the package turns the audit into the routine discipline of the plant: the feed and the factor give the production, the fuel and the temperatures give the input, the gas analysis and the shell scan give the outputs, and the closing error gives the truth about the measurements. The engineer of the modern plant runs the balance monthly, ranks the losses, justifies the projects with the numbers and measures the results with the next balance: the cycle of the thermal optimization that keeps the industry competitive.

The example of the sheet (the 500 t/h feed with the factor of 1.63 returning the 7,361.96 t/d of the clinker, the exhaust gas at 320°C carrying the 140 kcal/kg, the shell at 250°C radiating the 45 kcal/kg) shows the method with the concrete numbers, and the reader who follows the worked example masters the method. The heat balance workbook, the calculation sheets and the complete library of the process engineering knowledge are all part of the Complete Cement Technical Package: the 931 files, the one-time payment of $249.99, the instant download and the lifetime access, and the purchase button below delivers the balance sheet of the cement plant and the whole library of the engineer in one package.

This file is part of the Complete Cement Technical Package (931 files) available from cementequipment.org. Respective rights holders; library copy for the licensed single user.