WHR facilities generate power within cement plants by recovering heat from waste gas discharged during burning processes in the cooling and pre-heating stages. The captured energy is used as auxiliary power. Waste heat can be converted into electrical energy by a steam turbine generator, using steam produced by two sources: pre-heater waste gas (PH waste gas) and air quenching cooler waste gas (AQC waste gas).
WHR technology can provide low-temperature heating or generate up to 30% of the overall electricity consumed in a cement plant.
A WHR facility is a relatively complex system with multiple interrelated subsystems. The basic package for a steam-based system consists of heat recovery boilers or heat exchangers, a steam turbine, gearbox, electric generator, condenser, steam and condensation piping, lubrication and cooling systems, water-treatment system, electrical interconnection equipment and controls.
WHR-based electric power generation offers several advantages:
- Reduces the amount of purchased power (or reduces reliance on fossil-fuel-based captive power plants), which in turn reduces operating costs
- Mitigates the impact of future electric price increases
- Enhances plant power reliability
- Improves plant competitive position in the market
- Lowers plant-specific energy consumption, reducing greenhouse gas emissions (based on credit for reduced central station power generation or reduced fossil-fired captive power generation at the cement plant)
- From a sustainability standpoint, our WHR facilities are helping us reduce our environmental footprint
In Tunisia, after the liberalization of energy prices in Tunisia in 2015, energy costs became very high. We built a brand new Waste Heat Recovery facility that started working in 2017. The WHR facility is a good solution that has increased the competitiveness of our Ciments Jbel Oust plant in Tunisia. The new facility has reduced our annual power purchase by 30%.
By reducing purchase of power by 30% and using waste gases to generate power, we have reduced CO2 emissions by 87.19 tons per day in Tunisia.
We are the first company to install this type of equipment. We are leaders in this field in Tunisia. At the time we established the project, there was no regulation about WHR systems in the country, and we worked very closely with the Government in order to define it. We also involved the Tunisian Electricity and Gas Company.
Employees in the Ciments Jbel Oust plant received specific training, as well as a one-month training in China to learn from the supplier how to operate the equipment. The person in charge of the WHR facility in VC Tunisia also received training in the VC India plant.