CHEMICAL ENGINEERING TRANSACTIONS  
 

VOL. 76, 2019 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.aidic.it/cet 

Guest Editors: Petar S. Varbanov, Timothy G. Walmsley, Jiří J. Klemeš, Panos Seferlis 
Copyright © 2019, AIDIC Servizi S.r.l. 

ISBN 978-88-95608-73-0; ISSN 2283-9216 

Energy Savings in Cement Industry: Use of Heat Integration 

Approach and Simulation Tools 

Disha Ravipati, Shweta Singh, Harmitkumar Pandya, Sridhar Dalai* 

Scool of Engineering and Applied Science (SEAS), Ahmedabad University, Ahmedabad-380009, India 

sridhar.dalai@ahduni.edu.in 

In thermo-chemical process industries, Heat Exchanger Network design and retrofit represent an important part 

of the plant design. The purpose of this network is to maximise heat recovery from process streams entering 

and exiting process equipment, thereby lowering the overall plant costs. The use of Pinch Technology in design 

ensures maximum heat recovery and minimum energy consumption resulting in minimum cost of hot and cold 

utilities. Energy Integration of cement industry was carried out using the principle of Pinch Technology. In 

present case study, Heat Exchanger Network was designed by use of methodology of Aspen Energy Analyser 

software V10.0 and Pinch Technology. The optimum minimum approach temperature of 11 °C was used to 

determine the energy target and the Pinch Point Temperature was found to be 994.5 °C. The utilities targets at 

Minimum Approach Temperature were found to be 1.594x107 kJ/h and 1.075x108 kJ/h for hot and cold utilities 

respectively. Pinch Analysis is best energy integration technique, which saves more energy and utilities cost 

than the traditional energy technique. 

1. Introduction 

The cement industry is an important part of big chemical family. Cement is mostly used as raw material for any 

construction and modern infrastructure needs. Also the cement industry is an energy intensive industrial sector, 

where the energy requirement is approximately 40 % of total cost of production. The cement industry sector 

consumes 15-20 % energy among all the energy consuming sectors in India (Verma and Kumar, 2017) cement 

industry sector is one of the highest greenhouse gasses (GHG) emitting industrial sector, accounts for around 

5% of global anthropogenic GHG emissions. The cement producers are required to reduce carbon dioxide 

emissions for as minimum 15 % by 2050, which represents the direct reduction up to 913 Mt of CO2 (Boldyryev 

et al., 2016). For minimisation of CO2 emissions and its impact on environment, it is necessary to adopt more 

energy efficient technologies (Klemeš et al., 2014). The existing process of cement plant is indicating a huge 

gap for energy efficiency. The minimal temperature approach between both hot and cold side is 380 °C which 

indicates poor level of heat recovery. Pinch Technology is one way to improve the existing process of industries 

to increase their profitability through reduction in energy, water and raw materials consumption, reduction in 

GHG emissions, and waste generation. The Pinch Technology usage allows in finding the balance between 

energy and costs as well as the correct the position of utilities and heat exchangers (Auta et al., 2012). In this 

paper, researchers use the Pinch Technology for increasing the energy efficiency of cement industry (Boldyryev 

and Varbanov, 2014). 

Pinch Technology is based on the basic principles of first and second law of thermodynamics. It is easy to use, 

as it does not require any knowledge of complex mathematical formulation. Pinch Technology involves 

understanding of the concepts of Pinch Point, Composite Curves (CC), Grand Composite Curves (GCC) and 

HEN (Heat Exchanger Network) design. The design of Heat Exchanger Network is an important aspect of energy 

conservation, which leads to reduction in GHG emissions, and usage of external utilities in a plant. In this 

process, HEN is designed for a given minimum temperature difference (ΔTmin) resulting into Maximum Energy 

Recovery (MER) and minimum number of heat exchangers used (Manizadeh et al., 2018).  

 
 
 
 
 
 
 
 
 
 
                                                                                                                                                                 DOI: 10.3303/CET1976071 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Paper Received: 26/06/2019; Revised: 18/08/2019; Accepted: 18/08/2019 
Please cite this article as: Ravipati D., Singh S., Pandya H., Dalai S., 2019, Energy Savings in Cement Industry: Use of Heat Integration 
Approach and Simulation Tools, Chemical Engineering Transactions, 76, 421-426  DOI:10.3303/CET1976071 
  

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The first step in the design of HEN is to find the Pinch Temperature from the extracted process (both hot and 

cold) streams to reach the requirement of minimum external utilities through the Problem Table Algorithm / 

temperature interval method using minimum temperature difference. Next step is to design Heat Exchanger 

Network that satisfies these targets, and later it can be optimized in targeting levels by comparing energy cost 

and the capital cost of the network, so that the total cost is minimised (Bokan and Pople, 2015). The principles 

involved in Pinch Technology are simplified by introducing the commercial software like Aspen Energy Analyser, 

which is developed by Aspen Technologies Ltd. This software combines Pinch Technology and mathematical 

programming in the design of Heat Exchanger Networks. This work uses the available process stream data of 

a cement industry to design the Heat Exchanger Network with the help of Aspen Energy Analyser in order to 

explore the energy and cost saving opportunities available to the plant. 

2. Methodology 

The adopted methodology for this study is based on the study done by Boldyryev et al., 2016 and Verma and 

Kumar, 2017. The synthesis of optimal flow sheets for Pinch Analysis initially developed by Linnhoff et al., 1998 

and later other researchers followed the same for further development. In this work the Aspen Energy Analyser 

software developed by Aspen Technologies Ltd. was used for constructing of Composite Curve and design of 

Heat Exchanger Network. There are four key steps of Pinch Analysis in the design of Heat Exchanger Network 

for both new and existing processes: data extraction; targeting; HEN design and optimization. 

2.1 Data Extraction 

The stream data for cement industry is shown in below Table 1 the data extracted contains source temperature, 

target temperature, heat capacity flow rate (mass flow rate x specific heat capacity) of each stream and utility 

data and the cost data, which is helpful in determining the energy cost and capital investment. Calculation of 

heat duty for each stream is done by using Aspen Energy Analyser. The extracted data contains seven hot 

streams and nine cold streams.  

Table 1: Stream Table [Verma and Kumar, 2017] 

Stream  

Type 

Source  

Temperature  

(Ts, °C) 

Target  

Temperature  

( Tt, °C) 

Heat  

Capacity 

Flowrate  

(kJ/°C.h) 

H1 270 55 21.814 

H2 1,000 280 66.946 

H3 280 110 19.085 

H4 280 90 1.193 

H5 1,400 100 24.51 

H6 290 100 114.839 

H7 270 105 14.053 

C1 30 100 68.008 

C2 280 810 35.033 

C3 810 1,400 34.625 

C4 30 90 5.147 

C5 90 150 2.86 

C6 30 150 62.305 

C7 30 290 128.564 

C8 30 90 24.51 

C9 30 90 5.343 

2.2 Computer Simulation 

The basic information needed to carry out Pinch Analysis with the help of Aspen Energy Analyser are inlet and 

out let temperatures of process and utility streams and heat capacity flow rate. The calculation of enthalpy of 

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each stream is done by Aspen Energy Analyser. The Process Streams tab in Aspen Energy Analyser allows us 

to provide information about the process streams in the HEN. The Utility Streams tab allows us to provide the 

utilities used in the HEN to cool or heat the process streams (Bokan and Pople, 2015). In this study, we specified 

hot utility as a very high temperature steam and cooling utility as cooling water. The individual stream associated 

with default local heat transfer coefficient, which is calculated by Aspen energy Analyser.  

The Pinch Design Method (PDM) was used to obtain a Heat Exchanger Networks. The next procedure was 

creating a problem table, Composite Curve, Grand Composite Curve and the cascade diagram to obtain pinch 

temperature, minimum hot and cold utilities at minimum approach temperature. The following assumptions were 

considered for the design of a counter current and shell and tube Heat Exchanger Network: constant heat 

capacities and no phase changes, respectively (Dagde and Piagbo, 2012). The purpose of design HEN is to 

match the process-to-process streams with less usage of cold and hot utilities. The design of HEN is an 

arrangement of several heat exchangers, which reduces the external utilities in the plant. The optimum design 

of HEN is required to maximise the heat recovery with minimal total cost design. Therefore, it is very essential 

to synthesize an optimum HEN with the minimum operating and capital costs (Owat and Skolpap, 2019). 

3. Results and Discussion 

The results obtained on various steps are summarised in below sections. 

3.1 Minimum Temperature Approach 

In order to generate minimum energy targets, the ΔTmin (minimum approach temperature) value was specified 

for the problem. Minimum Temperature Approach or ΔTmin is the minimum temperature difference allowed 

between hot and cold streams in the heat exchanger. It is an important design parameter for the development 

of energy efficient Heat Exchanger Network, as its value affects capital and operating costs of the plant 

(AbuBakar et al., 2015) As minimum value of ΔTmin results in lower value of operating cost but higher value of 

equipment cost, while with lower value of ΔTmin the area required for heat exchanger would be more, thereby 

increasing the capital cost. While higher value of minimum approach temperature leads to a decrease in capital 

cost and increase in operating costs, as there is a rise in overall heat recovery. Therefore, an optimized value 

of ΔTmin is required to get a minimum value of both. But, for integration of different types of plants - like Oil 

refineries, Chemical plants, Petrochemical industries and many others, different ΔTmin values are optimum for 

each plant. According to the values based on Linnhoff March’s application experience, the value of ΔTmin for 

chemical industries is between 10 - 20 °C. The optimum value of ΔTmin was automatically obtained by using 

the range-targeting feature in Aspen Energy Analyser. The range targets plot is shown in Figure 1. The software 

tool simulates the capital and operating cost at the different values of ΔTmin and generates a graph of total cost 

vs ΔTmin (Nagamalleswara Rao, 2016). This graph gives the information corresponding to the optimization of 

the minimum approach temperature, which is calculated by minimising the total annual cost. It means finding 

the best compromise between utility requirements, heat exchange area and unit shell number. The value with 

the least total cost is then chosen as the optimum minimum approach temperature for this case study. From the 

range targets plot, a value of 11 °C was determined as the optimal value for case study. This is within the range 

value of 10 - 20 °C for chemical industry given in literature (Kemp, 2007).  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1: Range target plot to determine the optimal ΔTmin value 

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3.2 Pinch Analysis energy target results  

The next step is the determination of energy targets based on Composite Curves and minimum approach 

temperature, ΔTmin. After deciding the optimal value of ΔTmin, the hot and cold Composite Curves are 

combined and represented in a temperature-enthalpy graph, in the form of the combined Composite Curve. The 

Composite Curve (CC) provides the overall energy targets (minimum hot and cold utility demand) and pinch 

temperature, but graphical representation is not suitable for identifying appropriate utility levels and loads. The 

Grand Composite Curve (GCC) shows the interaction between the process and the utility stream. Therefore, a 

GCC was constructed from Problem Table Algorithm (PTA) method by using a simulation tool. To visualize the 

correspondence between CC and GCC, these are placed next to each other in Figure 2. 

 

 

Figure 2: a) Composite Curves (CC), b) Grand Composite Curve (GCC)  

In Figure 2a, the upper curve represents the hot Composite Curve while the lower curve represents the Cold 

Composite Curve and the overlapping region between the hot and the cold Composite Curves represents 

process-to-process heat exchange. The minimum distance between the curves shows minimum approach 

temperature (ΔTmin) and this point is known as Pinch Point. The area above the Pinch is heat sink, as there is 

an overshoot of Cold Composite Curve, which required hot utilities, and the part below the pinch is heat source, 

as there is a surplus of heat, which needs to be rejected by using cold utilities. 

From Figure 2b, it was observed that the overall energy targets and scope of process-to-process heat exchange. 

In Figure 2b, the point where duty is zero is called Pinch Point. The pocket in GCC represents process-to-

process heat exchange and from the graph it can be noticed that process-to-process heat exchange is maximum 

below the Pinch. 

Table 2: Targets demand based on Case Study Data 

Target Summary       

Energy Target (kJ/h) Area Target (m2) Pinch Temp (°C) 

Heating (kJ/h) 1.594*107 Counter Current (m2) 6,858.8 Hot (°C) Cold (°C)  

Cooling (kJ/h) 

 

1.075*108 1-2 Shell & Tube (m2) 7,786.6 1,000 989  

Total Minimum 17 Capital (Cost) 2.123*106    

Minimum for MER 18 Operating (cost)  4.574*102    

Shell 23 Total Annual (cost)  6.350*102   

 

The energy targets as shown in the above Table 2 are calculated with the help of Composite Curves. It can be 

observed from the table that the energy target for the process of heating and cooling are 1.594*107 kJ/h and 

1.075*108 kJ/h, while the area target is 7.786*103 m2 for the shell and tube heat exchanger. The hot and cold 

pinch temperatures are 1000 °C and 989 °C, whereas the pinch temperature is 994.5 °C. The heat exchanger 

cost index targets shown in the table are based on the Aspen Energy Analyser default values of cost and 

economic parameters for calculation, as the cost and operations information were not well known from the case 

study data. The existing cement industry uses 8.341*107 kJ/h (23,169 kW) of hot utility whereas minimum hot 

utility demand, determined by Pinch Analysis, is 1.594*107 kJ/h (4,428 kW). The process uses 1.750*108 kJ/h 

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(48,611 kW) of external cold utility compared to minimum cold utility demand 1.075*108 kJ/h (29,861 kW). The 

heat recovery is increased from 63,750 kW to 82,500 kW. It is reminded that in the existing process unit only 

63,750 kW of thermal energy is recovered. The existing process unit 18,750 kW is far from the MER design and 

can be recovered.  

3.3 Heat Exchanger Network analysis 

The process streams and utility streams data were used to design a Heat Exchanger Network. The Heat 

Exchanger Network design obtained is represented using a grid diagram and is shown in Figure 3. All the heating 

and cooling requirements of the process were combined together the result is shown in the Grid Diagram. The 

direction of flow of the stream was taken in to consideration for placing heat exchangers on the grid diagram. 

The process streams are shown as horizontal lines, with hot streams flow from left to right, while cold streams 

flow from right to left. This is very important parameter when placing heat exchangers before or after another 

heat exchanger on the streams. Simply the grid diagram is an overview of all the heating/cooling requirements 

of the process. The local heat transfer coefficient associated with the individual stream (HTC) is the default 

values calculated by Aspen energy Analyser. Flow rate, effective heat capacity flow rate and minimum approach 

temperature are the parameters used in Aspen energy Analyser. Grid diagram contains process streams, utility 

streams and heat exchangers. In the grid diagram, thick blue colour line represents cold stream, thick red colour 

line represents hot stream, grey circle shows that the process to process heat exchanger, blue colour circle 

represents cooler and red colour circle represents heater. 

 

 

Figure 3: Grid diagram of Heat Exchanger Network 

The process has seven hot streams and nine cold streams. The current HEN has eleven heat exchangers 

between process streams, one heater for heating by very high temperature stream and six coolers for cooling 

by cooling water. A summary of existing heat exchanger duty, area and temperature profile generated by Aspen 

Energy Analyser are given in Figure 4 for process-to-process stream, coolers and heater. The grid diagram 

shows that the current HEN is operated efficiently and recovers maximum energy from process streams with 

less usage of external utilities. However there is a possibility to improve it further. After base case design 

synthesis, the design was optimized to minimise the total annualized cost by using Aspen Energy Analyser. 

From results, authors observed that the optimized design also has simple structure and low operating cost. 

 

 

Figure 4: Heat exchangers parameters of base case design. 

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4. Conclusions 

This research has highlighted the importance of Pinch Technology in improving the performance of cement 

manufacturing process. This paper provides results that show a Heat Exchanger Network with maximum heat 

recovery among process streams, thereby reducing the external utility consumption. In this study, researchers 

considered one type of hot and cold utility to design HEN. After keeping the ΔTmin 11 °C, the hot and cold pinch 

are achieved at 1,000 °C and 989 °C. The result shows that the heat available in the process is 4,428 kW while 

the heat demand in the process is 29,861 kW, which indicates that more heat is to be supplied from the process 

than heat to be removed from the system. The results show that the external hot utility demand of the plant is 

far less than the cold utility demand of the plant. From the extracted data HEN is designed for the base case. 

The network with a ΔTmin of 11 °C is the most optimal where the largest energy savings are obtained with the 

appropriate use of utilities i.e., 80.89 % for hot utilities and 38.57 % for cold utilities is saved as compared to the 

current plant configuration. The excess heat recovery is increased by 22.73 % and use of this excess heat 

provides a way to reduce the use of primary energy and to contribute to global CO2 reduction. It has been 

observed that Pinch Technology as an Energy Integration technique saves more energy and utilities cost than 

the traditional energy technique, and this means saving of utility and capital cost. In future studies, stream 

splitting and heat loss should also be considered. This work allows making a retrofit of existing cement industry 

and general recommendation for further analysis of heat recovery and utility systems. The results of this paper 

will be used for Total Site analysis of cement plant and selection of heat transfer equipment. It is also 

recommended that further research could be conducted in using Pinch Technology to other industries. 

Acknowledgments 

The authors gratefully acknowledge the support of using Aspen Energy Analyser simulation tool at School of 

Engineering and Applied Science (SEAS), Ahmedabad University, during this research work. 

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