## A patented circular traveling firewave kind of reactor

This summer we visited the brickyard (Ziegeleipark) in the village of Mildenberg in the vicinity of Zehdenick. Brick fabrication started there already in 1887. This brickyard was one of the most important brickyards in the vicinity of Berlin. It provided the bricks which were necessary for the growth of Berlin. In 1910 it hosted 57 ring kilns. A ring kiln is also called a Hoffmann kiln, since it was invented and patented by a Mr. Hoffmann. The Hoffmann kiln has two floors. In such a kiln the fire “wanders” around the ring in the lower floor. It passes through chambers which contain bricks to be burned. The raw material is put via an outside door in a chamber in front of the fire and the burned bricks can be taken out of a chamber after the fire has passed through. The fire is moderated and controlled by hand via little holes in the floor of the upper floor through which coal can be passed through.

upper floor of a Hoffmann kiln:

The lower floor with the chambers (The chambers were partially separated with paper in order to avoid convection):

The entries to the chambers along the ring:

The working conditions were in former times very bad, here a translation without guarantee of the information in the above foto given at Ziegeleipark Mildenberg:

Often the whole family was working at the brickyard. While the men were working as “Streicher” (I could only find a french, italian or dutch translation) or cart pusher, the women were bringing the raw bricks into the brick shed in order to let them dry. Kids were partially helping to move around the bricks on the drying grounds. Their little feet fit in between the small clefts between the brick rows. Already at an early stage labour protection laws were curbing the workings of children and women. So heavy duty work like at the ovens and at the clay pits were forbidden and the working times were reduced bit by bit. The official minimal age of children was set to 13 years, after having finished school. But due to seldom controls and exemptions the observation of working laws were not always guaranteed.

After world war II the production in Mildenberg was continued. In the GDR not only the working conditions were improved, but a more modern process was introduced:

A congratulation to a good worker called Hannelore Kulas:

comments in german, french and russian will be translated into english.
you can use LaTeX in your math comments, by using the $shortcode: [latex] E = m c^2$