DE2021763A1 - Inert gas firing of ceramics with rapid gas flow and improved - heat transfer - Google Patents

Abstract

A ceramics firing process utilises chemically neutral hot gases in all temperature ranges. The gases are pref. swept at high speed over the whole surface of the ceramics, thus producing rapid heat transfer and accelerating all stages of preliminarly heating, finishing, firing and cooling.

Description

Process for firing ceramic goods.

DESCRIPTION OF THE PROCEDURE OF THE PROCEDURE When firing raw ceramic or other products, the economic viability largely depends on the time Duration of this process.

In the course of this firing process or the sin-firing process for glaze or decor on ceramic or other material, there are 3 phases to distinguish between them namely: a) the removal of the residual water in the blank and the subsequent heating the same to about 500 - 800 OC, depending on the chemical composition and structure.

b) Heating the same to the required cooking or stoving temperature the glaze or the decor.

How long the relevant oven insert has been at the required temperature must be kept depends on the purpose and composition of the insert pieces away.

c) The cooling of the furnace insert to the removal temperature.

This firing process was previously, depending on the type of material used, in Chamber furnace or continuous furnace with direct firing, muffle heating or electric Heating carried out.

Direct firing was only possible where there was no surface-refined one Insert pieces were used.

Muffle or electrical heating was required for decor or glaze firing be used.

Aside from economy, the last two had combustion processes the disadvantage that the furnace atmosphere stagnated and thereby the temperature transition went slowly and unevenly from the furnace atmosphere to the load.

As a result, the firing process section listed under a) was essential longer and more imperfect than it could have been.

The same disadvantages occurred in the cooling section of the firing process in reverse order. The heated material radiated warmth into the Furnace atmosphere. The temperature difference between the insert and the atmosphere in the The furnace was small and the change in furnace atmosphere was relatively slow.

The supply of outside air by means of a chimney draw-in or air blower for the accelerated change of the furnace atmosphere had the disadvantage that the Inserts located closer to fresh air cooled faster than those closer to the exit lying.

There was also the distribution of fresh air over the entire furnace area not controllable.

Temperature stresses in the insert pieces could not be chalked up.

The method described below now has, compared to the previous Sequence of the burning process, significant advantages through an essential Shortening the firing process and improving the quality of the items to be fired.

The new method is that the furnace does not need to be heated Heat transfer to the material to be fired through the hot Mutfelwand or the direct flame takes place.

The heating is done by 1 a at high speed from the burner Completely burnt out, chemically neutral exhaust gases entering the furnace chamber, their Temperature and volume can be programmed and automatically regulated as required can.

The effectiveness of the new heating process in the aforementioned 3 phases of the firing process is as follows: Due to the great turbulence of the furnace atmosphere the convective heat transfer between the furnace atmosphere and the load is very large.

Any remaining water in the input material quickly becomes excreted and discharged and the mass of the input material quickly and evenly warmed up.

The heat distribution in the entire furnace cross-section is completely the same and with no other type of heating so easily and inevitably possible.

It is clear that this type of heating reduces the drying time and the heating phase is shortened to a fraction of what was previously required.

After reaching a heating temperature adapted to the respective item to be fired, can then quickly and without damage to the items to be fired up to the cooking temperature can be increased.

The duration of the cooking phase depends on the type of material to be fired.

After the end of the cooking firing phase, the temperature of the heating gases increases reduced to 6 - 700 QC, which means that it is quick and safe for the load Cooling is achieved.

Depending on the type of material used, the heating temperature can then continue reduced and later turned off the gas completely and only cooled with air.

The advantage of the new combustion process is that all phases of the Firing process both in terms of temperature and the time sequence can be regulated and mastered exactly according to the program.

Since the heating gases are completely burned out after leaving the burner and are chemically neutral, all glazes and decors can be used in ovens without a muffle to be burned in.

Claims (5)

PATk.NTANSQUÜCHE 1.) The method characterized in that the one for heating Kiln for ceramic goods used heating gases in all temperature ranges have a chemically neutral atmosphere. 2.) Method characterized in that the heating gases are the material to be fired rinse the entire surface with great speed and thereby one cause rapid convective heat transfer between the heating gas and the input material. 3.) Method characterized in that the required The cooking firing temperature of the material to be used is strictly adhered to in terms of level and duration can be. 4.) Method characterized in that the cooling process of the material to be burned after the end of the cooking process by gradually reducing the heating gas temperature and the resulting faster temperature convection, without endangering the input material can be accelerated very strongly. 5.) Method characterized in that through the use of neutral hot exhaust gases for heating stoves also most glazes and decors, can be burned in if they come into direct contact with the heating gases.