The 4100 tpd plant burns low-volatile petcoke alongside alternative fuels, but the high moisture quantity of the fuel required near-constant use of a diesel-powered hot gas generator. With economic, environmental and operational benefits to be gained by ending the use of diesel in this process, the plant was keen to see if a waste heat alternative was a possibility.
An old idea, revisited
In an earlier project some years ago, FLSmidth and Cementos Molins had investigated the possibility of using waste heat from the preheater to dry coal in the mill, but the idea was abandoned due to the high capital costs. However, in the time since then the plant has switched from coal to petcoke (low volatile), a new, simpler solution came on the table: using waste heat from the cooler.
Together with Cementos Molins, colleagues from our offices in Denmark and Spain explored the potential of such a project, finding the idea to be both feasible and desirable, with economic and environmental advantages. Studies were undertaken to work out the best means of getting the gasses from the cooler to the mill, and we proposed a design that made it possible to avoid using the hot gas generator altogether.
Trust and expertise
FLSmidth has a strong and long-lasting relationship with Cementos Molins and was the main equipment supplier for the Sant Viçent dels Horts plant. Apart from having close knowledge of the plant, we also share the company’s sustainability ambitions and were called in to discuss this hot gas generator replacement project from the outset. This, in combination with our extensive capabilities and equipment knowhow, made us the natural choice of partner for this turnkey project, which was initiated in July 2020.
Having first participated in the process and engineering layout and design, once the contract was agreed our scope expanded to include equipment, engineering, programming of the relevant control systems, and commissioning. The range of equipment included cyclones, gas control valves, fan, ducting and sensors.
Building a bespoke solution
In order to develop a perfect-fit solution, we spent about 9 months on engineering process calculations, layout design, manufacturing design engineering, and full project planning to ensure a smooth and easy installation.
The project was undertaken under COVID restrictions, so we made good use of virtual meetings to prepare as much as possible. Careful project management was required in order to coordinate all our activities – both within FLSmidth, among our contractors, and with the plant team onsite.In the event the project was completed within scheduled annual shutdown, not requiring extending it to connect the ducts to the cooler and to the coal mill.
Mission accomplished
The installation of this waste heat bypass duct was completed in July 2021.
It enables Cementos Molins to stop using their hot gas generator, with a saving of 2790 tpa of CO2. In addition to the environmental saving, the plant also enjoys a lower cost of operation thanks to the use of waste gases that were previously voided to the atmosphere. Most importantly, the waste heat achieves its purpose, bringing the moisture level of the petcoke down from 12% to less than 0.5%, ensuring a more efficient grinding process.