Lime burning is energy-intensive and has a negative impact on the climate. Innvotive ideas can, however, contribute to sustainable benefits here as well. In addition to the optimised use of fuels, the further processing of CO2 from the exhaust gases can make a valuable contribution to climate protection.
To date, when dealing with lime kilns, there was always consideration about optimising the process for the production of quicklime. The CO2 emissions from the kilns were not taken into account.
This has changed fundamentally with the climate debate: innovatively and with a lot of passion, Maerz has worked step by step to enrich the CO2 in the kiln off-gas as high as possible. In the process, we filed patents for many inventions and finally developed the Maerz EcoKiln® series. The highly concentrated CO2 can thus be liquefied easily and fed into a further use or sequestration.
How the CO2 concept works: Instead of combustion air, recirculation gas, enriched with oxygen, is used (oxyfuel operation - CO2 cycle 1). In addition, the cooling air is extracted from the kiln before it can mix with the combustion gas. This is how we achieve a CO2 concentration of > 95 % in the off-gas.
A partial flow of the CO2-rich off-gas is fed to a heat exchanger to recover the heat contained in the cooling air (CO2 cycle 2). The CO2 intended for further use is cooled, in a contact cooler, to the temperature required for the next process steps.
A detailed description of this process can be found in our publication.
This process principle can be applied to all our shaft kilns. Both the HPS kilns and the larger PFR kilns are available as Maerz EcoKiln®.
If required, when the production of a CO2-rich kiln gas makes economic sense, conventional HPS or PFR kilns can also be upgraded with oxyfuel firing.
Our clear answer: Yes.
The Maerz EcoKiln® series can be expanded in several stages: in the simplest variant, only the combustion air can be replaced by the oxygen-enriched kiln gas (oxyfuel operation). This allows CO2 contents in the kiln off-gas of 40 - 45 % to be achieved. This configuration is ideal for use in the soda and sugar industries, where in many cases replacement investments for old mixed-fired kilns are due in the next few years.
A further argument for Maerz EcoKilns®: A Maerz kiln will last for approx. 50 years. In the next few years, we expect significant changes in emissions legislation worldwide and, as a result, a substantial increase in the cost of CO2 taxes. With a Maerz EcoKiln® in its basic configuration, you can easily respond to that. With slightly higher costs for new construction, you are investing in the future and can always keep your system at the cutting edge of technology.