**4. Representative case study**

#### **4.1. Data collection and reconciliation**

This case study was previously introduced by Boldyryev et al. [29, 30]. The energy expertise of the cement factory was conducted during the summer operation mode. The steady-state devices and portable equipment were used. The historical data of process monitoring were collected and analyzed. There are two operation modes of the particular cement factory. The first one is when the raw mill is under operation and, in this case, the cooling water flowrate at the cooling tower is 3 t/h. A hot gas from the kiln is fed into the raw mill and a raw material is heated. The second operation mode presumes that the raw mill is out of operation. In this case, the cooling water flowrate greatly increases and it is 11 t/h. At the same time, the waste heat with hot gases from the kiln is also increased. There are 18 process streams, which may be included to the heat integration of a particular cement factory. There is a heat recovery of an inspected cement plant and a necessary process heat is provided by the fuel combustion while a cooling capacity is delivered by ambient air that is pumped by air fans. **Table 1** has all necessary thermophysical parameters of process streams under analysis.


**4.2. Results and discussion**

*4.2.1. Existing process analysis*

Based on the energy expertise, heat balances and stream table data, the composites of the existing cement factory were constructed considering different operation modes of the raw

Heat Integration in a Cement Production http://dx.doi.org/10.5772/intechopen.75820 101

The composite curves in **Figure 2** present the energy requirements of the existing cement factory. The operation mode with the raw mill has a heat recovery of 41,125 kW, whereas the process requires extra heating of 19,397 kW and extra cooling of 20,225 kW. For the operation regime without raw mill it is necessary to have larger utility load as presented in **Figure 2**. The energy demands increase to 22,923 kW and 24,006 kW for heating and cooling, respectively. At the same time, the heat recovery decreases to 37,599 kW during raw mill operation mode. The minimum temperature approach of the heat exchanger network of the existing process with the raw mill operation is 247°C; without the raw mill operation, it goes up to 308°C. Both these temperature differences are calculated by energy expertise, mass and heat balances and data reconciliation. It should be noted that the minimum temperature approach of the particular process is 1°C due to direct heat transfer in a raw mill or at cement grinding. The raw mill operation mode is under further consideration to get low bound of energy-saving potential. It has to be extended in future by development of the factory operation modes taking into account fluctuations of process parameters and to develop a tool for operators. The significant difference between the thermodynamically grounded (see **Figure 2**) and real minimum temperature approaches may be additionally explained by cross-pinch heat transfer in the existing heat exchanger network. This is well presented in **Figure 3** by composite curves. Arrows show that the heat transfer from hot to cold streams and cross-pinch lines is absent as well as

**Figure 2.** Temperature profiles of a particular cement factory. 1—Hot composite; 2—cold composite raw mill operation mode; 3—cold composite no raw mill operation; QCmin = 24,006 kW—cold utility demands (cooling water, air);

mill. The composite curves of the existing process are presented in **Figure 2**.

cold utilities are used above the pinch in E-108 (**Figure 4**).

QHmin = 22,923 kW—hot utility demands (fuel) (developed after [30]).

**Table 1.** Extracted data of inspected cement factory: raw meal under operation.

Economic data of utilities were also extracted to be able to execute the economic calculation of the retrofit solution. There are two types of fuel supplied to the kiln: coal and petcoke. Cooling water cools down the exhaust gases before the filter bags; the water is fed by the desalination plant. Another cold utility is electricity, and it is used by the hot air coolers, which emerges from the clinker cooling. Cleaned and cooled air from air filter bags is ejected to the environment. A total of 15.6 MW of low-grade heat is ejected to the atmosphere during raw mill operation; this amount is increased up to 19.4 MW if the raw mill is turned off. All fans and pumps of the cooling tower use the electricity.

The primary fuel that is used for this particular cement factory is coal and petcoke. The coal/ petcoke ratio is 40/60%, and the caloric values of the fuel are 25.5 and 33 GJ/t, respectively, for coal and petcoke. The average power supply of the cement plant is 5.8 MW, whereas the minimum power consumption is 1.1 MW and the peak load reaches 10 MW. The reduced price of the hot utility is 75.9 EUR/kWy, and the cold utility is 82.0 EUR/kWy.

#### **4.2. Results and discussion**

#### *4.2.1. Existing process analysis*

Economic data of utilities were also extracted to be able to execute the economic calculation of the retrofit solution. There are two types of fuel supplied to the kiln: coal and petcoke. Cooling water cools down the exhaust gases before the filter bags; the water is fed by the desalination plant. Another cold utility is electricity, and it is used by the hot air coolers, which emerges from the clinker cooling. Cleaned and cooled air from air filter bags is ejected to the environment. A total of 15.6 MW of low-grade heat is ejected to the atmosphere during raw mill operation; this amount is increased up to 19.4 MW if the raw mill is turned off. All fans and

The primary fuel that is used for this particular cement factory is coal and petcoke. The coal/ petcoke ratio is 40/60%, and the caloric values of the fuel are 25.5 and 33 GJ/t, respectively, for coal and petcoke. The average power supply of the cement plant is 5.8 MW, whereas the minimum power consumption is 1.1 MW and the peak load reaches 10 MW. The reduced price of

the hot utility is 75.9 EUR/kWy, and the cold utility is 82.0 EUR/kWy.

**Table 1.** Extracted data of inspected cement factory: raw meal under operation.

pumps of the cooling tower use the electricity.

**№ Name of the stream Type Supply** 

8 Raw material in a raw

16 Ambient air for clinker

cooling

17 Clinker to cement grinding

18 Mineral components grinding

mill

100 Cement Based Materials

**temperature (°С)**

 Gases to raw mill Hot 370 105 13.35 3537.42 Gases from the kiln Hot 860 380 40.97 19,663.31 Hot gases to cooling Hot 370 175 11.68 2276.67 Gases to coal mill Hot 370 90 0.73 204.75 Clinker from the kiln Hot 1450 60 15.00 20,850.00 Air after clinker cooling Hot 290 100 70.28 13,352.75 Air to cement grinding Hot 270 105 8.86 1461.60

 Kiln raw material Cold 105 810 21.44 −15,114.42 Hot meal Cold 810 1450 21.19 −13,559.47 Coal/petcoke to coal mill Cold 25 90 3.15 −204.75 Coal dust to kiln Cold 55 170 1.75 −201.25 Air to the kiln Cold 25 170 38.13 −5528.29 Tires to the kiln Cold 25 170 0.14 −20.30 Used oil to kiln Cold 25 170 0.28 −40.48

**Target temperature (°С)**

Cold 25 110 41.62 −3537.42

Cold 25 290 78.68 −20,850.00

Cold 25 105 15.00 −1200.00

Cold 25 105 3.27 −261.60

**Heat capacity flowrate (kW/К)** **Heat load (kW)**

Based on the energy expertise, heat balances and stream table data, the composites of the existing cement factory were constructed considering different operation modes of the raw mill. The composite curves of the existing process are presented in **Figure 2**.

The composite curves in **Figure 2** present the energy requirements of the existing cement factory. The operation mode with the raw mill has a heat recovery of 41,125 kW, whereas the process requires extra heating of 19,397 kW and extra cooling of 20,225 kW. For the operation regime without raw mill it is necessary to have larger utility load as presented in **Figure 2**. The energy demands increase to 22,923 kW and 24,006 kW for heating and cooling, respectively. At the same time, the heat recovery decreases to 37,599 kW during raw mill operation mode. The minimum temperature approach of the heat exchanger network of the existing process with the raw mill operation is 247°C; without the raw mill operation, it goes up to 308°C. Both these temperature differences are calculated by energy expertise, mass and heat balances and data reconciliation. It should be noted that the minimum temperature approach of the particular process is 1°C due to direct heat transfer in a raw mill or at cement grinding. The raw mill operation mode is under further consideration to get low bound of energy-saving potential. It has to be extended in future by development of the factory operation modes taking into account fluctuations of process parameters and to develop a tool for operators. The significant difference between the thermodynamically grounded (see **Figure 2**) and real minimum temperature approaches may be additionally explained by cross-pinch heat transfer in the existing heat exchanger network. This is well presented in **Figure 3** by composite curves. Arrows show that the heat transfer from hot to cold streams and cross-pinch lines is absent as well as cold utilities are used above the pinch in E-108 (**Figure 4**).

**Figure 2.** Temperature profiles of a particular cement factory. 1—Hot composite; 2—cold composite raw mill operation mode; 3—cold composite no raw mill operation; QCmin = 24,006 kW—cold utility demands (cooling water, air); QHmin = 22,923 kW—hot utility demands (fuel) (developed after [30]).

**Figure 3.** Heat transfer in cement production with raw mill considering the minimum temperature difference. 1—Hot composite curve; 2—cold composite curve, 3—heat exchangers (developed after [30]).

Grid diagram shown in **Figure 4** illustrates the initial heat exchanger network representing the heat transfer between the hot and cold process streams and utilities. The grid diagram illustrates cross-pinch heat transfer; it is a reason of increased utility consumption and lowered efficiency. It is a result of concept design, which was done without the use of optimal heat exchanger network methods and mostly oriented proper product quality.

The process design, which was oriented to obtain a product rather than energy efficiency, reduces opportunities for overall efficiency of plant operation as highlighted in [31]. The overview of heat exchangers placement of the initial plant design is shown in **Table 2**. The initial cross-pinch transfer is now greater than 20 MW that confirms the low efficiency of the initial

Heat Integration in a Cement Production http://dx.doi.org/10.5772/intechopen.75820 103

By providing pinch analysis, it is possible to get thermodynamically available energy targets for particular cement production that shows a large energy-saving potential. Eliminating the cross-pinch heat transfer and cold utility use above the pinch, it is possible to decrease energy consumption and heat recovery improvement. Additionally, the minimum temperature approach may be lowered to minimize the energy targets. This is well illustrated in **Figure 5** by composite curves position for ΔTmin = 20°C. Energy targets for hot and cold utilities are 4076 and 4904 kW, respectively; the heat recovery is enlarged up to 56,446 kW; the heat recov-

However, the cement manufacturing process has different features previously mentioned in Part 3 of this chapter, such as process streams with a mixture of solid-gas and others. These issues make the feasibility of the heat exchanger network retrofit with maximum heat recovery as impossible. Based on this, the heat exchanger network of the cement factory has huge energy efficiency potential, but it is not easy to achieve a profitable solution owing to the pro-

It is impossible to avoid process restrictions when implementing an integrated solution. There are some process streams that have such technological limits. First one is a hot meal that has to be heated from 810 to 1450°C inside the kiln. It is not possible to heat it in another with particular technology. Another issue that should be analyzed additionally is clinker from the

cess limitation connected to heating and cooling process streams No 5 and No 10.

design of the heat exchanger network.

**Table 2.** Analysis result of heat exchanger placement.

*4.2.2. Maximization of heat recovery considering process limitations*

**Heat exchanger label Cross-Pinch heat transfer (kW)**

E-100 2229.0 E-101 133.1 E-102 0.0 E-103 3180.0 E-104 261.6 E-105 1200.0 E-106 1132.0 E-107 12,088.5 E-108–E-113 0.0 Network cross-pinch load 20,224.2

ery improvement in case of maximum saving is 15,321 kW.

**Figure 4.** Grid diagram of existing cement production (developed after [30]).


**Table 2.** Analysis result of heat exchanger placement.

Grid diagram shown in **Figure 4** illustrates the initial heat exchanger network representing the heat transfer between the hot and cold process streams and utilities. The grid diagram illustrates cross-pinch heat transfer; it is a reason of increased utility consumption and lowered efficiency. It is a result of concept design, which was done without the use of optimal

**Figure 3.** Heat transfer in cement production with raw mill considering the minimum temperature difference. 1—Hot

heat exchanger network methods and mostly oriented proper product quality.

composite curve; 2—cold composite curve, 3—heat exchangers (developed after [30]).

102 Cement Based Materials

**Figure 4.** Grid diagram of existing cement production (developed after [30]).

The process design, which was oriented to obtain a product rather than energy efficiency, reduces opportunities for overall efficiency of plant operation as highlighted in [31]. The overview of heat exchangers placement of the initial plant design is shown in **Table 2**. The initial cross-pinch transfer is now greater than 20 MW that confirms the low efficiency of the initial design of the heat exchanger network.

#### *4.2.2. Maximization of heat recovery considering process limitations*

By providing pinch analysis, it is possible to get thermodynamically available energy targets for particular cement production that shows a large energy-saving potential. Eliminating the cross-pinch heat transfer and cold utility use above the pinch, it is possible to decrease energy consumption and heat recovery improvement. Additionally, the minimum temperature approach may be lowered to minimize the energy targets. This is well illustrated in **Figure 5** by composite curves position for ΔTmin = 20°C. Energy targets for hot and cold utilities are 4076 and 4904 kW, respectively; the heat recovery is enlarged up to 56,446 kW; the heat recovery improvement in case of maximum saving is 15,321 kW.

However, the cement manufacturing process has different features previously mentioned in Part 3 of this chapter, such as process streams with a mixture of solid-gas and others. These issues make the feasibility of the heat exchanger network retrofit with maximum heat recovery as impossible. Based on this, the heat exchanger network of the cement factory has huge energy efficiency potential, but it is not easy to achieve a profitable solution owing to the process limitation connected to heating and cooling process streams No 5 and No 10.

It is impossible to avoid process restrictions when implementing an integrated solution. There are some process streams that have such technological limits. First one is a hot meal that has to be heated from 810 to 1450°C inside the kiln. It is not possible to heat it in another with particular technology. Another issue that should be analyzed additionally is clinker from the

procedure [23] does not take into account the technological restrictions, for example, as for particular cement manufacturing, and does not have a feasible solution. In our case, the minimum of total reduced cost corresponds to ΔTmin = 29°C (see **Figure 7**). Nonetheless, the design of the retrofit for ΔTmin = 29°C has the same energy targets as one with ΔTmin = 50°C but the

Based on results presented in **Figure 6**, the targets of the retrofit design of cement production are taken, including the minimum temperature approach, energy requirements and pinch

The grid diagram shown in **Figure 8** is the base concept of a new heat exchanger network of a cement factory with minimized energy consumption. It has additionally installed four heat

of 5790.08 kW. The basic parameters of the new heat exchangers are illustrated in **Table 3**. The new heat exchanger network is presented in **Figure 8**, and it is shown that there is still a large cross-pinch transfer of 8850 kW. This issue may be additionally investigated in the future research of new efficient technologies of cement manufacturing. The cross-pinch heat transfer of the proposed heat exchanger network is illustrated in **Table 4**; there is only one cross-pinch

The estimated total investment for new heat exchanger network implementation is 256,079 EUR, accounting the installation cost of E-114 and E-115 as 5000 and 10,000 EUR and 30,000 EUR for E-116 and E-117, respectively. The price of the heat transfer area is 800 EUR per 1 m2

and the nonlinearity price coefficient is 0.87. A new concept design allows reduction of operation cost of 914,401 EUR/year assuming 8200 operation hours per annum. The simple payback period of investments is 3.4 months. By applying the process integration approach, the energy consumption is lowered by 2.56 GJ/t of produced cement, which is 14% less than the existing

**Figure 7.** Super targets of cement production. 1—Operation cost; 2—investments; 3—total cost (developed after [30]).

and total recovered heat energy

Heat Integration in a Cement Production http://dx.doi.org/10.5772/intechopen.75820

,

105

heat transfer area is much higher (see **Figure 6**).

exchangers with an estimated heat transfer area of 1555.1 m2

*4.2.3. New concept of retrofit design*

point position.

heat exchanger.

**Figure 5.** Composite curves of cement production with maximum heat integration. 1—Hot composite curve; 2—cold composite curve with raw mill operation; QHmin = 4076 kW—hot utility demands; QCmin = 4904 kW—cold utility demands (developed after [30]).

kiln; it has to be cooled down rapidly to 60°C. This is done in the existing process by big fan coolers, and the heat of air is ejected to the environment.

The maximum possible heat recovery of the cement factory taking into account the process restrictions was previously discussed in this chapter. There is an energy target (see right Y-axis, **Figure 6**) and pinch temperatures (left Y-axis, **Figure 6**); these indexes depend from the minimum temperature approach of the heat exchanger network. **Figure 6** shows energy targets (lines 1 and 2 in **Figure 6**, right axis Y) of the cement factory, which may be lowered to a process limit that is 50°C. The reduction of ΔTmin below 50°C is useless, as shown in **Figure 6**, due to its increases in the cross-pinch heat transfer and heat transfer area while the energy consumption remains unchanged. This issue also influences the heat exchanger network topology and reduces the cross-pinch heat transfer. The traditional super targeting

**Figure 6.** The definition of maximum heat recovery taking into account process restrictions. 1—Cold utility target; 2 hot utility target; 3—hot pinch temperature; 4—cold pinch temperature (developed after [30]).

procedure [23] does not take into account the technological restrictions, for example, as for particular cement manufacturing, and does not have a feasible solution. In our case, the minimum of total reduced cost corresponds to ΔTmin = 29°C (see **Figure 7**). Nonetheless, the design of the retrofit for ΔTmin = 29°C has the same energy targets as one with ΔTmin = 50°C but the heat transfer area is much higher (see **Figure 6**).

#### *4.2.3. New concept of retrofit design*

kiln; it has to be cooled down rapidly to 60°C. This is done in the existing process by big fan

**Figure 5.** Composite curves of cement production with maximum heat integration. 1—Hot composite curve; 2—cold composite curve with raw mill operation; QHmin = 4076 kW—hot utility demands; QCmin = 4904 kW—cold utility demands

The maximum possible heat recovery of the cement factory taking into account the process restrictions was previously discussed in this chapter. There is an energy target (see right Y-axis, **Figure 6**) and pinch temperatures (left Y-axis, **Figure 6**); these indexes depend from the minimum temperature approach of the heat exchanger network. **Figure 6** shows energy targets (lines 1 and 2 in **Figure 6**, right axis Y) of the cement factory, which may be lowered to a process limit that is 50°C. The reduction of ΔTmin below 50°C is useless, as shown in **Figure 6**, due to its increases in the cross-pinch heat transfer and heat transfer area while the energy consumption remains unchanged. This issue also influences the heat exchanger network topology and reduces the cross-pinch heat transfer. The traditional super targeting

**Figure 6.** The definition of maximum heat recovery taking into account process restrictions. 1—Cold utility target; 2—

hot utility target; 3—hot pinch temperature; 4—cold pinch temperature (developed after [30]).

coolers, and the heat of air is ejected to the environment.

(developed after [30]).

104 Cement Based Materials

Based on results presented in **Figure 6**, the targets of the retrofit design of cement production are taken, including the minimum temperature approach, energy requirements and pinch point position.

The grid diagram shown in **Figure 8** is the base concept of a new heat exchanger network of a cement factory with minimized energy consumption. It has additionally installed four heat exchangers with an estimated heat transfer area of 1555.1 m2 and total recovered heat energy of 5790.08 kW. The basic parameters of the new heat exchangers are illustrated in **Table 3**. The new heat exchanger network is presented in **Figure 8**, and it is shown that there is still a large cross-pinch transfer of 8850 kW. This issue may be additionally investigated in the future research of new efficient technologies of cement manufacturing. The cross-pinch heat transfer of the proposed heat exchanger network is illustrated in **Table 4**; there is only one cross-pinch heat exchanger.

The estimated total investment for new heat exchanger network implementation is 256,079 EUR, accounting the installation cost of E-114 and E-115 as 5000 and 10,000 EUR and 30,000 EUR for E-116 and E-117, respectively. The price of the heat transfer area is 800 EUR per 1 m2 , and the nonlinearity price coefficient is 0.87. A new concept design allows reduction of operation cost of 914,401 EUR/year assuming 8200 operation hours per annum. The simple payback period of investments is 3.4 months. By applying the process integration approach, the energy consumption is lowered by 2.56 GJ/t of produced cement, which is 14% less than the existing

**Figure 7.** Super targets of cement production. 1—Operation cost; 2—investments; 3—total cost (developed after [30]).

Making an additional analysis with taking into account site-heating needs and power demands of a cement factory other solutions were also proposed in this chapter. The waste heat potential may be used, for example, for electricity generation with use of Organic Rankine Cycle, which is shown in **Figure 9a**. The heat sources, in this particular case, are process streams 3

Heat Integration in a Cement Production http://dx.doi.org/10.5772/intechopen.75820 107

The estimated investment cost of power generation design is about 3.4 million EUR. The analysis of site demands in winter operation mode identified the other option of waste heat utilization, which is a district heating system. The low-grade heat potential of existing cement factory is given in **Figure 9b** (see curve 3) and due to this measure it is possible eliminating cold utility while the hot utility remains. In a particular case, the primary cold utility is power for air fans (680 kW), and from the other side, 20,225 kW of site heating demands may be covered by low-grade waste heat. The implementation of winter mode retrofit measures requires an estimated investment cost of 20.3 million EUR. The total saving of both retrofit designs during winter and summer operation modes is 7.648 million EUR. The payback time of combined retrofit for winter and summer

and 6 (for more details see **Table 1**), and the calculated power generation is 2482 kW.

**Heat exchanger Cross-pinch heat transfer (kW)**

E-100–E-102 0.0 E-103 8850.0 E-104–E-118 0.0 Network cross-pinch load 8850.0

**Table 4.** Cross-pinch heat load of retrofitted heat exchanger network.

operation modes is 3.01 per year assuming the total investment cost of 23.7 million EUR.

An additional analysis of the energy-saving heat exchange system for cement factory presents a room for improvement in terms of efficient energy use. The grid diagram of the proposed

**Figure 9.** Composite curves of cement manufacturing for low-potential heat utilization; a—summer operation mode; b—winter operation mode; 1—hot composite curve; 2—cold composite curve with raw mill operation; 3—site heating

*4.2.4. Impact and future work*

demands; QHmin—hot utility demands (developed after [29]).

**Figure 8.** A grid diagram of a retrofit concept design of cement factory (developed after [30]).


**Table 3.** Calculated parameters of new additional heat exchangers of cement factory.

benchmark level. The developed new concept design of energy-efficient cement manufacturing demonstrates the feasible and profitable solution that could be potentially used for retrofit as well as new factory design.


**Table 4.** Cross-pinch heat load of retrofitted heat exchanger network.

Making an additional analysis with taking into account site-heating needs and power demands of a cement factory other solutions were also proposed in this chapter. The waste heat potential may be used, for example, for electricity generation with use of Organic Rankine Cycle, which is shown in **Figure 9a**. The heat sources, in this particular case, are process streams 3 and 6 (for more details see **Table 1**), and the calculated power generation is 2482 kW.

The estimated investment cost of power generation design is about 3.4 million EUR. The analysis of site demands in winter operation mode identified the other option of waste heat utilization, which is a district heating system. The low-grade heat potential of existing cement factory is given in **Figure 9b** (see curve 3) and due to this measure it is possible eliminating cold utility while the hot utility remains. In a particular case, the primary cold utility is power for air fans (680 kW), and from the other side, 20,225 kW of site heating demands may be covered by low-grade waste heat. The implementation of winter mode retrofit measures requires an estimated investment cost of 20.3 million EUR. The total saving of both retrofit designs during winter and summer operation modes is 7.648 million EUR. The payback time of combined retrofit for winter and summer operation modes is 3.01 per year assuming the total investment cost of 23.7 million EUR.

#### *4.2.4. Impact and future work*

benchmark level. The developed new concept design of energy-efficient cement manufacturing demonstrates the feasible and profitable solution that could be potentially used for retrofit

**Cold stream Hot stream Load (kW) Area (m<sup>2</sup>**

**Name Tin**

coolers

coolers

coolers

coolers

Total 5790.08 1555.1

**(°C)**

**Tout (°C)**

290 275.6 20.30 3.4

290 261.2 40.48 6.7

290 242.3 201.30 39.9

290 202.6 5528.00 1505.1

**)**

**Figure 8.** A grid diagram of a retrofit concept design of cement factory (developed after [30]).

**(°C)**

25 170 Hot air to

55 170 Hot air to

**Name Tin (°C) Tout**

E-114 Tires to the kiln 25 170 Hot air to

E-117 Air to the kiln 25 170 Hot air to

**Table 3.** Calculated parameters of new additional heat exchangers of cement factory.

as well as new factory design.

E-115 Used oil to the kiln

E-116 Coal dust to the kiln

**Heat exchanger**

106 Cement Based Materials

An additional analysis of the energy-saving heat exchange system for cement factory presents a room for improvement in terms of efficient energy use. The grid diagram of the proposed

**Figure 9.** Composite curves of cement manufacturing for low-potential heat utilization; a—summer operation mode; b—winter operation mode; 1—hot composite curve; 2—cold composite curve with raw mill operation; 3—site heating demands; QHmin—hot utility demands (developed after [29]).

heat exchanger network of the cement plant (**Figure 8**) has illustrated the ways to use waste heat. The potential of waste heat may be used for power generation by heat engines' application as demonstrated by Quoilin and Lemort [32]. The heat duty of waste gas is 14,338 kW and the temperature is 200°C or higher (see **Figure 8**). However, if the plant is operated in the mode without a raw mill, the power generation increases as well. Important points that have to be additionally discussed are the fluctuations of plant operation parameters, solid– gas source streams and installation features of power generator.

**Acknowledgements**

**Author details**

Stanislav Boldyryev

**References**

(SDEWES Centre), Zagreb, Croatia

10.1016/j.jclepro.2014.04.011

669. DOI: 10.1177/0734242X14538309

10.1016/j.applthermaleng.2014.08.051 [7] Hasanbeigi A, Menke C, Price L.The CO<sup>2</sup>

This work was supported by the EC and Croatian Ministry of Science Education and Sports project "CARBEN" (NEWFELPRO Grant Agreement No. 39). The author acknowledges Holcim Company for provided data and personally Zoran Mohorovic for help in data extraction and reconciliation. The author acknowledges a SDEWES Centre and the Department of Energy, Power Engineering and Environment, Faculty of Mechanical Engineering and Naval

The Centre for Sustainable Development of Energy, Water and Environment Systems

[1] Mikulčić H, Vujanović M, Duić N. Improving the sustainability of cement production by using numerical simulation of limestone thermal degradation and pulverized coal combustion in a cement calciner. Journal of Cleaner Production. 2015;**88**:262-271. DOI:

[2] IEA (International Energy Agency). Cement Technology Roadmap 2009: Carbon Emissions Reductions up to 2050. 2009. Available from: www.iea.org/publications/freepublications/ publication/Cement\_Roadmap\_Foldout\_WEB.pdf [Accessed: November 05, 2016] [3] Mikulčić H, von Berg E, Vujanović M, Duić N. Numerical study of co-firing pulverized coal and biomass inside a cement calciner. Waste Management & Research. 2014;**32**:661-

in the EU cement industry. Energy. 2011;**36**:3244-3254. DOI: 10.1016/j.energy.2011.03.016 [5] Liu F, Ross M, Wang S. Energy efficiency of China's cement industry. Energy.

[6] Chen H. Technical benefit and risk analysis on cement clinkering process with compact internal burning of carbon. Applied Thermal Engineering. 2015;**75**:239-247. DOI:

try. Journal of Cleaner Production. 2010;**18**:1509-1518. DOI: 10.1016/j.jclepro.2010.06.005

emissions

Heat Integration in a Cement Production http://dx.doi.org/10.5772/intechopen.75820 109

abatement cost curve for Thailand cement indus-

[4] Pardo N, Moya JA, Mercier A. Prospective on the energy efficiency and CO<sup>2</sup>

1995;**20**(7):669-689. DOI: 10.1016/0360-5442(95)00002-X

Architecture, University of Zagreb, for administrative support.

Address all correspondence to: stas.boldyryev@fsb.hr

Another option of waste heat utilization from integrated cement production is the covering of site heating demands. The district heating system may be potentially supplied by waste heat to fulfill energy demands. The maximum capacity of waste heat that may be used is 14,338 kW as illustrated earlier. However, the technical implementation, including the heat losses and pressure drops, has to be additionally analyzed in details along with the economic issues of the retrofit design as well as energy planning. The results presented in this chapter have a cross-disciplinary impact and additional potential for future development of new cement manufacturing processes. A new design of a heat exchanger network could be a part of an energy-efficient environmentally friendly cement manufacturing process. It reduces fossil fuel consumption, CO2 emission and operation cost of cement factories.

The utilization of low-grade heat for district heating systems could help for planning energy systems. The cement manufacturing process may be also considered as an energy source of district heating systems, additional power generation and so on. Nevertheless, the locations of cement factories have to be additionally analyzed with use of other systematic techniques, for example, based on total site analysis [33] to find a solution really close to the optimum.
