Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - CLEANKER (CLEAN clinKER production by Calcium looping process)

Teaser

The cement industry is a key-sector for the reduction of CO2 emissions. CO2 generation in cement production processes in fact, cannot be disregarded due to the calcination of limestone, the most important raw material, which accounts around 60% of the direct CO2 emissions from...

Summary

The cement industry is a key-sector for the reduction of CO2 emissions. CO2 generation in cement production processes in fact, cannot be disregarded due to the calcination of limestone, the most important raw material, which accounts around 60% of the direct CO2 emissions from the clinker burning process. In addition, there are the emissions from combustion, as well as from the generation of electric power required by the process as indirect CO2 emissions. Cement production is thus responsible for about 27% of global anthropogenic CO2 emissions from industrial sources worldwide and for 6 to 7% of global anthropogenic CO2 emissions.
There are currently no feasible methods to produce clinker, and thus cement, without releasing CO2 from calcination of CaCO3. In addition to oxyfuel combustion and post-combustion solvent-based capture technologies, Calcium Looping (CaL) is recognized as another very promising emerging technology for CO2 capture in cement plants. CaL is a regenerative process, which takes advantage of the capacity of calcium oxide-based sorbents to capture CO2 at high temperatures. The process is divided in two basic steps: (1) the capture of CO2 by “carbonation” of CaO to form CaCO3 in a reactor operating around 650°C; and (2) oxyfuel calcination in a reactor operating above 900-920°C, which makes the CaO available again and releases a gas stream of nearly pure CO2.
The highly integrated CaL process configuration enables CO2 capture with an efficiency target over 90% and high-energy efficiency. The overall energy consumption can be kept low by proper integration with raw meal preheating and heat recovery from the kiln flue gases.
The core activity of the project is the design, construction and operation of a CaL demonstration system including the entrained-flow (EF) carbonator and the EF oxyfuel calciner. This demonstration system, connected to the Buzzi Unicem kiln of the Vernasca cement plant (Italy), will capture the CO2 from a portion of the flue gases of the kiln, using as CO2 sorbent the same raw meal that is used for clinker production. Other activities will include: (i) screening of different raw meals to assess their properties as CO2 sorbent, (ii) reactors and process modelling, (iii) scale-up study, (iv) economic analysis, (v) life cycle assessment, (vi) CO2 transport, storage and utilization study, (vii) demonstration of the complete value chain, including mineral carbonation of waste ash with the CO2 captured in the pilot system, (viii) exploitation study for the demonstration of the technology

Work performed

CLEANKER is structured in 9 work packages shown in Figure 1. The first one-and-a-half-year main results are related to (i) raw meal characterization, (ii) modelling, (iii) engineering, (iv) CO2 mineral carbonation, (v) methodology for CCUS scenarios modelling and (vi) regulations.
(i) Characterization of the raw meal: experimental tests under conditions as close as possible to those expected in the CLEANKER CaL pilot have been carried out using Vernasca raw meal. Calcination tests in air-blown and in oxyfuel conditions were performed in laboratory EF reactors. In addition, carbonation tests of the calcined material in TGA apparatus were carried out. Carbonation and calcination conversions at different conditions, as well as the belite formation (Ca2SiO4, a stable compound whose formation uses part of the free CaO) and decay constants have been investigated
(ii) Modelling of the pilot plant focused on heat and mass balances (D2.3) of the demonstrator under different relevant operating conditions to support the design of the pilot. In addition, new models (D5.3) for the global pilot plant and for the coupled calciner and carbonator reactors were validated. Modelling for raw meal characterization focused on quantifying the kinetics rates of calcination and carbonation. Compared to natural limestones, the Vernasca calcined raw meal presented a complex behavior as sorbent, mainly due to the formation of belite. The decay constants obtained are shown to be comparable to typical values reported for other standard limestones
(iii) Based on modelling activities, the layout of the CaL Vernasca demonstrator was defined. Interconnections to the existing plant, quantification of additional loads to be considered in the existing structures, identification of all measuring devices and drive motors, definition of measurement points and instrumentation and definition of all individual machinery and piece of equipment were detailed (D2.1 and D2.4)
(iv) Different waste materials including burnt oil shale, concrete demolition wastes, cement by-pass dust and blast furnace slag sampled from Estonian, Italian and German power plants and Buzzi Cement Plant in Italy were tested via wet direct carbonation method (D7.4). Selected types of burnt oil shale and cement by-pass dust could be used as effective sorbents in the proposed CO2-mineralization process, binding up to 0.18 kg CO2 per kg of waste
(v) Methodology for techno-economic modelling of the Baltic and Italian CCUS scenarios, including database structure, is developed in D7.1
(vi) International and national regulations related to CCUS technology and their national implementations are studied in detail (D7.3) and compared for the five countries (Italy, Estonia, Latvia, Lithuania and Russia) involved in the planned CCUS scenarios of the CLEANKER project
During the first 18 months, particular attention was devoted to the communication activities. The CLEANKER website was launched and CLEANKER is on twitter (@CLEANKER_H2020). In addition, the project has published 3 newsletters and organized public events for the stakeholders of the local community where the demo plant will be erected as well as for scientific communities, industry and policy makers interested in CCS.

Final results

The CLEANKER demonstrator will progress the CO2 capture from cement plants via CaL technology in industrial environment (TRL7). Up to now, research on CaL systems focused on the application of this technology in coal-fired power plants and in cement plants as a tail end CO2 capture process, based on a dual circulating fluidized bed system.
The progresses beyond the state of the art that CLEANKER will achieve by the end of the project are:
• Design and operation of a novel EF CaL reactor system specifically developed for application in cement plants
• Unprecedented screening on the properties of different raw meals as CO2 sorbent
• A full validation of the EF CaL reactors and the description of the fundamental phenomena governing the integrated CaL process by reaction sub-models
• CO2 transport, storage and utilization study. In addition, mineralization of Estonian waste oil shale ash with experimental tests in the Vernasca plant site will be performed
Potential impact of CLEANKER project is expected at different levels:
• Environmental and societal, through mitigation of climate change. The capture of 90% of CO2 is one of the most important CLEANKER target to be demonstrated during the experimental campaigns
• Technical-scientific, through the creation of new knowledge both at experimental and modelling levels
• Social, through the increase of the public awareness on CCS and on sustainable cement production. For this purpose, different successful events have been organized, both with general public, local communities and local and regional administrations

Website & more info

More info: http://www.cleanker.eu.