Update on electric cement kilns

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Coolbrook has been in the news recently with collaboration deals struck with Cemex and UltraTech Cement. First the Finland-based company officially launched its Roto Dynamic Heater (RDH) technology with a memorandum of understanding signed with Cemex in May 2022. Then, this week, it signed a similar agreement with UltraTech Cement.

The specifics of either agreement are unknown but the target is clearly to build an industrial pilot of an electric kiln – or something like it - at a cement plant. Coolbrook says it has run a pilot of its RDH technology in Finland. Further tests are now scheduled to continue for two years starting from September 2022 at the Brightlands Chemelot Campus at Geleen in the Netherlands. Commercial scale demonstrations are scheduled from 2022 with the hope of commercial use from 2024. Links with Cemex and UltraTech Cement seem to suggest progress. At the same time Coolbrook will be testing its RotoDynamic Reactor (RDR) technology, which promises to electrify the steam cracking process used in plastic manufacturing.

Publically available details on the RDH technology are light. In its promotional material Coolbrook says that it can achieve process temperatures of up to around 1700°C. This is crucial to achieve full clinker formation in a cement kiln. Reaching this temperature with non-combustion style kilns, such as solar reactors, has previously been a problem. Notably, Synhelion and Cemex said in February 2022 that they had managed to produce clinker using concentrated solar radiation. Retrofit possibilities and compact equipment size are also mentioned in the promotional material for the RDH. The former is an obvious attraction but size of equipment footprint is increasingly emerging as a potential issue for cement plants looking to reduce their CO2 emissions. Rick Bohan from the Portland Cement Association (PCA) presented a summary of the potential and problems of emerging carbon capture and utilisation/storage (CCUS) technologies for cement plants in the US at the Virtual Global CemCCUS Seminar that took place on 14 June 2022. He noted that installing CCUS equipment makes cement plants start to look different (more like petrochemical plants in the view of Global Cement Weekly) and that they may require more space to install it all.

Coolbrook hasn’t been the only organisation looking at kiln electrification. The installation with the most available information on kiln electrification has been the Decarbonate project, led by the VTT, formerly known as the Technical Research Centre of Finland. The project has built a pilot rotary kiln with a length of 8m inside a shipping container. It has a production capacity of around 25kg/hr. The system reportedly uses fixed radiant heating coils around the kiln, surrounded by insulation materials. Early results presented to the 1st Virtual Global CemPower Seminar in late 2021 were that the kiln started up, sufficient calcination was occurring and the system was operated continuously for three days at a temperature of 1000°C with no problems reported. Further research was scheduled to carry on into 2022 with longer trials planned for three different materials.

HeidelbergCement’s subsidiary in Sweden, Cementa, completed a feasibility study on implementing electrified cement production at its Slite plant in 2019. It then said that it was conducting further study with electricity producer Vattenfall as part of CemZero project. This consists of three projects running to 2025. Namely: heat transfer with plasma in rotary kilns; direct separation of carbon dioxide from calcination of carbonate-based raw materials in the production of cement clinker and burnt lime; and carbon dioxide-free products with electrified production - reactivity of cement clinker with secondary additives. HeidelbergCement has since announced plans to build a full scale 1.8Mt/yr carbon capture and storage (CCS) plant at the Slite cement plant by 2030.

How this would fit with any kiln electrification plans is unknown. However, one attraction of moving to an electrical kiln, for all of the projects above, is to cut out the 40 – 50% of a cement plant’s CO2 emissions that arise from the fuel that is burnt. Taking a kiln electric also makes CO2 capture easier. Much of the remainder of the CO2 released comes from the decomposition of limestone during calcination when clinker is created. Substitute out fossil or alternative fuels and the flue gas becomes much purer CO2.

It is early days for cement kiln electrification but progress is happening both commercially and scientifically. The next step to watch out for will be the first pilot installation at a cement plant. One point to finish with is a comment that Rick Bohan made at the IEEE-IAS/PCA Cement Industry Technical Conference that took place in May 2022: carbon capture is expected to double a cement plant’s energy consumption. Kiln electrification is one potential route for cement production to reach net zero. CCUS is another. If one or both occur then a low carbon future could be a high energy one also.

Watch out for Global Cement’s forthcoming interview with Coolbrook in the September 2022 issue of Global Cement Magazine

For more on CCUS, download the proceedings pack for the Virtual Global CemCCUS Seminar 2022

For more on Synhelion and Cemex read the interview in the December 2020 issue of Global Cement Magazine interview

Last modified on 15 June 2022

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