This final year project focuses on direct heat recovery in which heat from various units such as the Kiln, Calciner and Clinker Cooler is recovered. For this study, a process model is developed using Aspen HYSYS simulation software, and the model is confirmed against acquired data from the industry followed by calculation of equal fuel saved. The heat recovered from all these units is used to produce superheated steam to run a steam turbine generator which in turn provides electricity to the cement plant. This is an implementation of the Steam Rankine Cycle. This project not only benefits the industry in terms of cost-saving on fuel but also reduces the quantity of toxic hot waste gases. The number of carbon emissions would have increased drastically if coal would have been used instead. The steam turbine was able to generate 14 MW. If this is successfully implemented in all other major industries, a significant amount of non-renewable reserves can be saved for future generations.

1. WASTE HEAT RECOVERY
FROM HOT GASES IN
CEMENT INDUSTRY
Hanan Rehman, 2017138
Huzaifa Kamran, 2017160
Abu Bakar, 2017029
Noor Ahsan, 2017362
Advisor Name: Dr. Javaid Rabbani Khan
Co-Advisor Name: Dr. Hammad Amjad Khan

2. Introduction
DG Cement is the largest cement manufacturer of Pakistan with its production capacity of 14,000 tons
per day. DG Cement plant at Chakwal has a total power requirement of 31MW.
Cement Industry
 High energy dependent industry
 Loss of large amount of energy
(Kiln, Calciner and Clinker Cooler)
 Energy represents largest share
in overall manufacturing cost (40-
60%)
 Reducing the production cost by
minimizing the energy cost
 WHR is widely used throughout
the world.
 Heat energy from hot flue gases is
converted to electricity.
Types of WHR systems
 Rankine Cycle (Water)
 Kalina Cycle (Water & ammonia)
 Organic Cycle (N-Pentane)
Literature Review
Fig.1: Rankine cycle

3. Motivation
 Energy production:
 Utilization of waste hot flue gases to
produce electricity
 Increase in energy efficiency up to 20%
 Less burden on National grid of a low
energy producing country like Pakistan
 Economization:
 Reduction in operational and process cost
for example: clinker production
 Less cost of electricity
 Reduction in loss of water through cooling
tower
 Global warming:
 Lower CO2 emission
 Less use of water resources
 Low temperature of waste gases entering
the atmosphere

4. Gap Analysis
• In DG-Cement Kalina cycle is used for WHR system but it is:
a. Less efficient (10%-15%).
b. Storage problem.
c. Expensive (Additional cost of ammonia mixture).
d. Unable to fulfill energy requirements (produced only 5MW).
• Cooling tower which is currently being used results in:
a. Water loss through Evaporation and Drift
b. Use of make up water from nearby resources such as lakes and ponds For Example;
Katas Raj Temples.
Primary Objectives
• Heat recovery from different heat sources such as Calciner and Clinker Cooler From
Rankine Cycle.
• Modelling & Simulation will be performed using Aspen HYSYS simulation software.
• Calculations will be performed using industrial data for amount of fuel saved, turbine
efficiency, cooling tower efficiency and overall efficiency of system.
Secondary Objectives
• Introducing double turbine system to increase overall efficiency of the process.
• Replacing cooling tower with ACC to minimize water loss and operational cost.
• Utilization of waste heat from Diesel Generators

5. Cooling Tower Air Cooled Condenser
Fig.2: Cooling tower working principle Fig.3: ACC working principle

6. Parameters Values
Turbine Operating Pressure 1 MPa
Turbine Operating Temperature 315°C
Inlet hot air Temperature 383°C
Outlet hot air Temperature 95°C
Feedwater mass flow rate 45.8 ton/hr
Mass of air per kg of Clinker Produced 0.98 kg air/kg clinker
Mass of Clinker produced 291,000 kg/hr
Waste gases inlet Temperature 295°C
Waste gases outlet Temperature 200°C
The volumetric flow rate of gases 205000 m3/hr
Composition of CO2 68%
Composition of N2 8%
Composition of O2 2%
Composition of CO 2%
Composition of H2O 20%
Specific heat capacity of waste gases from generator 1.862 kJ/kg.K
Industrial Data

7. Process Flow Diagram
Fig.4: PFD for single pressure turbine

8. Process Flow Diagram
Fig.5: PFD for Dual pressure turbine

9. Aspen HYSYS Simulation Model
Fig.6: Aspen HYSYS Model

10. Aspen HYSYS Simulation Worksheet
Fig.6: Data of Aspen HYSYS

11. Commercialisation possibilities & social impact:
 This model of WHR can be used
as a reference for other
industries.
 Not only limited to cement
industries.
 Implementation of WHR
Commercially would reduce
energy crisis of Pakistan.
 Since it is Environmental friendly,
it won’t have any adverse effect
on health of employees
 It will increase job opportunities.
 Ensure safety of natural
habitats.
 Improvement of social
reputation.

12. ABOUT THE
PROJECT
Gantt
Chart

13. Gantt
Chart
Results
 Successfully utilized the Heat of Diesel Generators in driving
dual pressure turbine
 Saved water up to 5000 liters/month by using ACC instead of
Cooling Tower
 Reduced emission of CO2 up to 9000 tonnes
 Meeting the SDGs by reducing the risk of Global warming
 WHR system based on Rankine cycle operating at an
efficiency of up to 25%
 Reduced electrical power consumption from the national
grid up to 11MW through single pressure turbine and
14MW through dual pressure turbine

14. 1. http://www.yuvaengineers.com/waste-heat-recovery-power-plant-sk-anwar-basha/
2. CEMENT, D. (2017-2018). Financial Report . Lahore: Nishat Group.
3. M.Rahim, A. A. (2015). Waste Heat Recovery Power Generation Systems for Cement Production Process.
EEE TRANSACTIONS ON INDUSTRY APPLICATIONS.
4. Robert McCaffrey. (2018, June 1). DG Khan Khairpur: The ‘self-sufficient’ cement plant. Retrieved from
Global Cement: https://www.globalcement.com/magazine/articles/1071-dg-khan-khairpur-the-self-
sufficient-cement-plant
5. Y. Redjeba*, K. K.-D. (2019). Aspen Plus based simulation for waste heat recovery in cement industries.
Department of process engineering, National Polytechnic School of Constantine, Algeria.
6. Waste Heat Recovery System. (2015, June 20). Retrieved from MAN Diesel & Turbo:
www.mandieselturbo.com
7. Performance of an air-cooled steam condenser for a waste-to-energy plant over its whole operating range
(Energy Conversion and Management 52 (2011) 1908–1913)
8. Thekdi, A. C. (1998). Industrial Waste Heat Recovery: Potential Applications, Available Technologies.
National Technical Information Service.
References

15. THANK YOU