Autoclaving
The last step in the production of AAC is the autoclaving. This is how the aerated concrete, among other things, achieves its final strength.
The autoclaving is carried out in long pressurised vessels; the autoclaves are designed for an operating pressure of 12 bar. Our standard chamber has a diameter of 2.75 m or 2.9 m (depending on the best stacking procedure) and a length of 39 m. These dimensions allow six autoclave carriages with a total of 18 cakes to be accommodated. An individual adjustment of the dimensions to your own needs is of course possible. We would be pleased to advise you about this.
For any particular recipe, the autoclaving process is carried out in precisely defined procedural steps. The normal duration is between ten and twelve hours. The whole process in our production systems is automated. Each and every step can be individually set by the WKB System control element.
In comparison to other AAC technologies, the advantage of the WKB Systems autoclaved aerated concrete plant is not only the saving of energy, but also the reduction of material used due to the efficient utilisation of the autoclave vessel. In our systems the hardening of the bottom layer can also be dispensed with.
Another advantage is that the single blocks stand on their heads and are spaced from one another by the GSM (Green Cake Separation Machine). This will prevent them from sticking together during the autoclaving process. As a result there is no need to use of a separator after the autoclaving process completed.
The steam required for the autoclaving is generated by a boiler in the boiler house fired either with gas or oil. The hardening of the material in the autoclave is the main steam consuming process step. Several autoclaves are usually operated in a staggered manner. This has the advantage that the waste steam from one autoclave can be used to heat up another autoclave using a steam distributor. This results in significant fuel savings.
In the planning of the autoclave section of an autoclaved aerated concrete plant, WKB Systems attaches great importance to waste heat recovery. This not only concerns the continued use of the steam, but also utilisation of the collected condensate. Using the WKB technology, the condensate formed by the autoclave can be used e.g. in the mixing plant or the mill. Heat from the condensate can be recovered with a heat exchanger to heat the building or for preheating the feed water. This also leads to further fuel savings.
