DE19821607C2 - Process for drying tiles, especially roof tiles - Google Patents

Description

The invention relates to a method for drying Bricks, especially roof tiles, according to the generic term of claim 1.

Known methods for drying bricks, in particular Roof tiles that are mainly used in large systems see a drying of the bricks except for one Residual moisture content of 1%, the drying time takes approx. 20 to 30 hours. After drying the bricks are partly engobed and then fired, e.g. B. in one Tunnel furnace according to DE 39 18 746 A1. In this oven is an external line designed as a heat exchanger provided about the circulating gases from the heating zone in the Circulation are traceable, the line also in one Dryer, the products before entering the Pass through the treatment channel. The recirculation gases remain through this return line separated from the atmosphere in the dryer. It is avoided that volume and composition of the circulating gases through Steam or warm air from the drying process are falsified, or that pollutants from the  Circulating gases are formed by condensation on the wet, cold surface of the blanks can settle.

The dryer is preferred as a tunnel dryer with a or several channels or as a chamber dryer with trained several chambers.

There is also provision for the tunnel kiln and Dryer arranged in a common building become. Advantages are less wall loss, one lower heat consumption in both units, shortest Paths for heat transfer from the oven to the dryer smallest possible space requirement and low construction costs for both units. However, these advantages do not lead to Reduction of the long ones already mentioned at the beginning Drying time.

The object of the invention is to create a method which enables a significant reduction in drying times light and further an improvement on one Bricks, especially on a roof tile Quality characteristics brings about.  

The task solves a process for drying bricks, in particular roof tiles, according to claim 1 the features mentioned.

The inventors recognized that only by leaving the prevailing view among experts that Brick in the process of burning upstream Drying at once to at least 1% residual moisture, should be dried to an even lower value if possible, the task is solvable.

The new drying process is based on known ones Processes in which the bricks on a so-called Pallet are placed at a distance from each other and to Drying in a dryer, preferably Is part of the large brick production plant, are given. What is new and inventive here is that the bricks in the dryer only to a residual moisture of 4% to 6%, preferably dried to 4.8% to 5.3% become. In addition, the dryer, preferably a Tunnel dryer, only a so-called sliding air blown in, which removes the moist air and only a very has low flow velocity. The necessary Drying heat is preferably generated by radiant heaters transferred to the bricks. The further lowering of the Residual moisture of the brick except for that for firing  necessary value of approx. max. 1%, done by convectionally stimulated normal evaporation during the The bricks stay in between the dryer and the furnace area, the so-called Delivery area, with a special version in this said area a residual water dryer is provided. Among other things, this is advantageous if under Circumstances from the design of the entire large system forth said delivery area for further lowering the residual moisture should not be sufficient.

Another special version of the new process is that the one in front of the kiln used residual water dryer and / or the heating zone of the kiln can be used to dry residual water.

The new process for drying bricks is also particularly advantageous for engobed bricks. In a further development of the invention, it is specifically provided here that the engobe after the first drying phase on the a little damp brick is abandoned before in the second drying phase the evaporation down to approx. 1% Residual moisture takes place.

The application of the engobe on the still slightly damp Brick surface brings more essential  Quality improvements for the bricks, since there are none additional swelling on the brick surface occur as when applying the engobe to one dry brick with a residual moisture of 1% or less 1% occur.

Drying in the dryer is the main drying, so to speak in the subordinate area, the so-called delivery area, the residual drying, the u. a. also final drying is called.

The main advantages of the invention are u. a. a gentle drying, lower energy consumption as well improving on a brick, especially on put a roof tile and its engobe Quality features.

Claims (10)

1. A method for drying tiles, in particular roof tiles, in which tiles placed on so-called pallets at a distance from one another are placed in a dryer for drying, characterized in that the tiles in the dryer in a first drying phase to a residual moisture content of 4% to 6 % are dried and then, in an area upstream of a kiln, a further reduction in the residual moisture to at least 1% takes place in a second drying phase. 2. The method according to claim 1, characterized, that the further lowering of the residual moisture in the second Drying phase at normal temperature Evaporation takes place.   3. The method according to claim 1, characterized, that the further lowering of the residual moisture in the second Drying phase at an elevated temperature convectionally excited evaporation takes place. 4. The method according to claim 3, characterized, that the second drying phase for further lowering the residual moisture to at least 1% in one Residual water dryer takes place. 5. The method according to claim 2 and 3, characterized, that in the second drying phase in addition to Evaporation at normal temperature in one residual water immediately upstream of the kiln dryer by convectionally excited evaporation increased temperature the residual moisture value of at least 1% is set.   6. The method according to any one of claims 1 to 5, characterized, that the process with continuous dryers is carried out. 7. The method according to any one of claims 1 to 5, characterized, that drying with at least one tunnel dryer is carried out. 8. The method according to any one of claims 1 to 7, characterized, that an engobe before the first drying phase on the damp brick is applied. 9. The method according to any one of claims 1 to 7, characterized, that an engobe after the first drying phase on the still wet brick is applied.   10. The method according to any one of claims 1 to 7, characterized, that an engobe before the second drying phase on the still wet brick is applied.