The Pegasus (Plant Evaluation, Gap Analysis and Support Service) Project is a multi-company benchmarking and knowledge sharing project. It is designed to help World Cement Association (WCA) member cement plants identify the gap between their plants and industry best-practice. This will help cement producers to prioritise performance improvement projects, evaluate investment options, gain different perspectives and, ultimately, achieve greater overall sustainability. The Pegasus Project 2020 and the first round of data collection was launched in September 2020. It gathered data from 10 WCA members, with a total of 90 integrated lines and 31 grinding stations that jointly represent 107.6Mt/yr of cement production capacity.
Phase 1
The first phase of the Pegasus Project involved extensive virtual project meetings with participating plants, three rounds of data collection to ensure correct and aligned data and thorough analysis to produce a comparative benchmark across different operations. There was particular focus on energy consumption and CO2 emissions, with 22 Key Performance Indicators (KPIs) considered.
These included:
- Clinker specific heat consumption (SHC);
- Clinker specific power consumption (SPC);
- Cement grinding SPC;
- Clinker CO2 emission intensity;
- Cement CO2 emission intensity;
- NOx, dust and SO2 emissions.
Participants then received 1:1 presentations to identify priority areas for improvements at their plant(s). The aim is to help WCA participating members get the most value from Pegasus. As such, WCA not only provides benchmarking and comparison of where the participants fit in, but also provides the top five plants’ performances (Figure 1), as well as best practices that others could follow.
Findings
Key factors that affect energy efficiency include the age of the plant, capacity of the line (lines below 3500t/day have a disadvantage), type of grinding process, the number of preheater stages, equipment selection and management / operating practices. It came as no surprise that the plants with the lowest heat and power consumptions used:
- Raw meal grinding roller presses;
- High efficiency grate coolers;
- High efficiency fans (especially for ID, kiln and cooler exhausts);
- Variable speed drives (VSD) for process fans rather than damper controls.
The process design for these plants included low pressure drop main dust collectors and low pressure drop preheaters with 5 - 6 stages. There was also a contribution from up-to-date technology such as advanced process control (APC) systems, energy management system, manufacturing execution systems (MES) and on-line condition monitoring via vibration, pressure, temperature and other sensors.
There were several best practices in management and operations that can be referenced at all plants. These include:
- Reward and recognition of shifts/teams with the best performance;
- Management of overall fan system efficiency;
- Effective management of air leakage;
- Good control of clinker temperature to avoid wasting energy on unneeded cooling;
- Optimising oxygen levels in the kiln;
- Effective management of material flow to eliminate blockages;
- Monitoring and minimising idle running time.
Two priority areas
The benchmarking showed that there are two priority areas to consider:
1. Fan system efficiency: The process fans’ installed power is 35% of the total power of the plant. In most cases it is possible to reduce SPC by 5 - 10% in just a few months, without significant investment. Typical payback time on the modest investment required is around six months. Table 1 shows the potential benefits.
2. Conveyor load management: Conveyors and bucket elevators are often used ineffectively. Figures 2 - 4 show the hours with normal running, idle running and low load running at a Pegasus Project participant. Optimising effective run time is an easy and cheap way to save energy. Only a low-cost monitoring system needs to be installed, alongside a change in habits.
Fan | Best (kWh/t) | Worst (kWh/t) | Factors that affect SPC |
ID Fan | 5.1 | 9.5 | Fan efficiency, temperature and pressure of cyclone 1 outlet, O2, VSD |
Cooler Fans | 4.4 | 10 | Fan efficiency, cooling air density, VSD |
Cooler Exhaust Fan | 1 | 5 | Fan efficiency, VSD, overcooling |
Kiln Exhaust Fan | 1.3 | 7 | Fan efficiency, VSD, pressure drop of bag house, air leakage |
Table 1: The difference between the best and worst fan power consumption performances among Pegasus Project participants indicates significant opportunities for improvement. VSD = Variable speed drive.
Lessons learned, opportunities for improvement
The project continues to be a two-way conversation, with members raising questions on data analysis and giving feedback on the process. WCA recently established an Operations and Performance Professional Committee, which oversees and drives the Pegasus Project forwards. Its first task was to prepare a Self-Assessment Tool Kit (SATK), including workshop and equipment level specific power consumption. Participating members can use this as a check list to identify gaps and opportunities for improvement.
The committee will also identify priority topics for improvement. Best practices will be disseminated on the WCA website, and member forums will be organised to share knowledge and findings. These lessons will be taken forward and applied to Phases 2 and 3 of the project, which will look at maintenance, reliability, operations and ‘Industry 4.0.’
Participant feedback
Feedback from WCA members has been very positive. Delon Perumal of PPC South Africa, said “We have got new perspectives and methodologies from the WCA team that we have not previously considered. Some add value, some open up new understanding and some we can challenge. This has made this project very enjoyable and a good experience. It’s definitely something I’d recommend and encourage people to get involved with.”
Speaking of benefits to the company, Ahmed Safraoui of CIMAT stated, “Pegasus opens our view to benchmarking with much broader scope to gain greater experience and resources than we can internally. We have seen the situation of our company compared with other WCA members, and we have seen issues and areas where we can improve our performance and we have undertaken some actions, set new targets and assigned new priorities.”
Pegasus 2022
The next intake of data will begin in 2022, when Pegasus 2022 will kick-off a new round of benchmarking and allow WCA to track improvement. This will highlight improvements and changes compared to the previous year and allow for analysis of trends year on year to be produced. “I am confident that we could see good results from many plants,” concludes Rosy Wang of the WCA. “Indeed we have already observed improvements at some of our participating companies.”
A detailed report summarising the outcomes of Phase 1 will be published on the WCA website in August 2021. WCA looks forward to welcoming further participants to the Pegasus 2022 intake.