GB2129165A

GB2129165A - Controlling kilns

Info

Publication number: GB2129165A
Application number: GB08327389A
Authority: GB
Inventors: Uwe Rothe; Peter Maier; Dietrich Thiede; Ullrich Manz; Steffen Petermann; Jurgen Zuschke
Original assignee: KERAMIK WTB VEB
Current assignee: KERAMIK WTB VEB
Priority date: 1982-10-19
Filing date: 1983-10-13
Publication date: 1984-05-10
Also published as: DD218948A2; JPS59135505A; GB8327389D0

Abstract

A further development of Serial 2107904A provides for the detection of disturbance variables, particularly mass flow, within the heating, firing and cooling zones. Information is obtained on the course which the temperature is expected to take in a zone at the kiln by one or more additional upstream measuring points and is then conveyed to a regulating apparatus and the regulating section initially influenced synchronously in accordance with the dynamic characteristics of the section. Stochastic disturbance factors which do not influence the over-all process or which owing to the brief duration of their influence cannot be balanced out, are eliminated for the stabilization of the process, information on the operating state being obtained from one or more measuring points and evaluated according to a mathematical model or determined by mathematical means only from a measuring point by forming gradients for the temperature characteristics in each case.

Description

SPECIFICATION Controlling kilns for firing ceramic products This relates to the controlling of kilns used for firing ceramic products and is an improvement to the method described in application 8229680 (2107904A). In this prior application there is provided a method for predetermining disturbances caused to the conditions in a kiln for firing ceramic products, wherein the parameters which affect the firing, such as the mass and/or geometry of the kiln transport means, are detected at a point in the travel path of the transport means, the information detected being used for control at fixed points in the heating, firing and cooling zones of the kiln to optimize the firing conditions.

According to specification 2107904, (not prior published), those parameters of a transport means (hearth carriage or slide) which determine the firing process and which result from the total mass of the loaded transport means less the tare subordinate to the firing process and the geometry of the super-structure on the transport means, are detected at any desired point in the conveyor system of the transport means outside the tunnel or continuous kiln. The information obtained is conveyed to a computing system for the processing of the data. The data is used for pre-optimising the heating, firing and cooling zones. We have found that the processing of the information obtained is not adapted to the firing process long enough to enable the firing of ceramic products to be influenced in the necessarily optimum manner.

An object of this invention is to enable the temperature variations which occur inside the tunnel or continuous kiln at fixed points in the heating, firing and cooling zones and which are caused by variable mass flow disturbances to be compensated by an optimum technique and anticipatory energy reactions.

The stabilization of the firing process in the heating, firing and cooling zones is intended to provide the conditions for the introduction of an optimum firing curve, thus enabling the specific energy consumption to be reduced and the furnace performance improved, in addition to rendering the firing process hardware more durable and ensuring a better-quality product.

This invention seeks to extend the method for detecting the mass flow outside tunnel and continuous kilns, according to 2107904, to provide for the detection of the disturbances inside the heating, firing and cooling zones.

This invention enables this object to be achieved by a method in which, through one or more additional measuring points preceding the fixed points, in the area of the heating, firing and cooling zone which is to be stabilized, reliable information is obtained on the course which the temperature is expected to take in the stabilizing zones. This information is conveyed to a regulating apparatus and the regulating section is preliminarily influenced synchronously in accordance with the dynamic characteristics of the said section.

Stochastic disturbance factors which do not influence the over-all process or which due to the short duration of influence cannot be balanced out, are eliminated for the stabilization of the process, information on the operating state being obtained from one or more measuring points and evaluated according to a mathematical model or determined by purely mathematical means from a measuring point by forming gradients for the temperature characteristics in each case.

Example This invention will be explained in greater detail by reference to an example.

The predominant disturbance variable which is the mass flow, which in the firing process causes the temperature to drop when lightly loaded hearth carriages or slides are replaced by more heavily loaded ones or causes it to increase in the reverse case, is detected by additional measuring points. These measuring points precede the zone to be stabilized. In one or more furnace areas advance information is obtained on the course which the temperature is expected to take in the zone to be stabilized, as a result of the change in the mass flow. By means of a simple mathematical model a significant decision is taken concerning the disturbance variable due to an appreciable mass flow change or to stochastic parameters resulting from the specific features of the ceramic firing process.

Temperature changes caused by structural differences in the hearth truck such as saggar or partitition loading, or different assortments are detected by additional measuring points. This evaluation is also carried out by a simple mathematical model or by purely mathematical means, the disturbance being calculated from one measuring point only, by calculating the rise of fall in the temperature course in each case. If the value obtained is within a temperature fluctuation range corresponding to a permissible tolerance band, this change is eliminated. In the event of a deviation from the tolerance band of the measuring points provided or if the temperature takes the same course at two or more measuring points, this acts on the control device via a differentiation element. The information points are so arranged that the distance between them does not exceed the length of a hearth truck or slide.

The regulated value in the zone to be stabilized is controlled in advance by taking into account the transition characteristics of the regulating section and by the aid of a computer programme, so that in the said zone the mass flow disturbance is balanced out. The computer programme for the pre-optimization contains the rate of feed through as a variable.

Claims

1. Method for predetermining disturbances caused to the conditions in a kiln for firing

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Controlling kilns for firing ceramic products This relates to the controlling of kilns used for firing ceramic products and is an improvement to the method described in application 8229680 (2107904A). In this prior application there is provided a method for predetermining disturbances caused to the conditions in a kiln for firing ceramic products, wherein the parameters which affect the firing, such as the mass and/or geometry of the kiln transport means, are detected at a point in the travel path of the transport means, the information detected being used for control at fixed points in the heating, firing and cooling zones of the kiln to optimize the firing conditions. According to specification 2107904, (not prior published), those parameters of a transport means (hearth carriage or slide) which determine the firing process and which result from the total mass of the loaded transport means less the tare subordinate to the firing process and the geometry of the super-structure on the transport means, are detected at any desired point in the conveyor system of the transport means outside the tunnel or continuous kiln. The information obtained is conveyed to a computing system for the processing of the data. The data is used for pre-optimising the heating, firing and cooling zones. We have found that the processing of the information obtained is not adapted to the firing process long enough to enable the firing of ceramic products to be influenced in the necessarily optimum manner. An object of this invention is to enable the temperature variations which occur inside the tunnel or continuous kiln at fixed points in the heating, firing and cooling zones and which are caused by variable mass flow disturbances to be compensated by an optimum technique and anticipatory energy reactions. The stabilization of the firing process in the heating, firing and cooling zones is intended to provide the conditions for the introduction of an optimum firing curve, thus enabling the specific energy consumption to be reduced and the furnace performance improved, in addition to rendering the firing process hardware more durable and ensuring a better-quality product. This invention seeks to extend the method for detecting the mass flow outside tunnel and continuous kilns, according to 2107904, to provide for the detection of the disturbances inside the heating, firing and cooling zones. This invention enables this object to be achieved by a method in which, through one or more additional measuring points preceding the fixed points, in the area of the heating, firing and cooling zone which is to be stabilized, reliable information is obtained on the course which the temperature is expected to take in the stabilizing zones. This information is conveyed to a regulating apparatus and the regulating section is preliminarily influenced synchronously in accordance with the dynamic characteristics of the said section. Stochastic disturbance factors which do not influence the over-all process or which due to the short duration of influence cannot be balanced out, are eliminated for the stabilization of the process, information on the operating state being obtained from one or more measuring points and evaluated according to a mathematical model or determined by purely mathematical means from a measuring point by forming gradients for the temperature characteristics in each case. Example This invention will be explained in greater detail by reference to an example. The predominant disturbance variable which is the mass flow, which in the firing process causes the temperature to drop when lightly loaded hearth carriages or slides are replaced by more heavily loaded ones or causes it to increase in the reverse case, is detected by additional measuring points. These measuring points precede the zone to be stabilized. In one or more furnace areas advance information is obtained on the course which the temperature is expected to take in the zone to be stabilized, as a result of the change in the mass flow. By means of a simple mathematical model a significant decision is taken concerning the disturbance variable due to an appreciable mass flow change or to stochastic parameters resulting from the specific features of the ceramic firing process. Temperature changes caused by structural differences in the hearth truck such as saggar or partitition loading, or different assortments are detected by additional measuring points. This evaluation is also carried out by a simple mathematical model or by purely mathematical means, the disturbance being calculated from one measuring point only, by calculating the rise of fall in the temperature course in each case. If the value obtained is within a temperature fluctuation range corresponding to a permissible tolerance band, this change is eliminated. In the event of a deviation from the tolerance band of the measuring points provided or if the temperature takes the same course at two or more measuring points, this acts on the control device via a differentiation element.The information points are so arranged that the distance between them does not exceed the length of a hearth truck or slide. The regulated value in the zone to be stabilized is controlled in advance by taking into account the transition characteristics of the regulating section and by the aid of a computer programme, so that in the said zone the mass flow disturbance is balanced out. The computer programme for the pre-optimization contains the rate of feed through as a variable. Claims

1. Method for predetermining disturbances caused to the conditions in a kiln for firing ceramic products, wherein the parameters which affect the firing, such as the mass and/or geometry of the kiln transport means, are detected at a point in the travel path of the transport means, the information detected being used for control at fixed points in the heating, firing and cooling zones of the kiln to optimize the firing conditions, characterized by: a) one or more additional measuring points within the tunnel furnace or continuous furnace preceding the zone of the heating, firing and cooling zones which is to be stabilized, and b) the information obtained for the zone to be stabilized being conveyed to a control apparatus.

2. Method for predetermining disturbances in kilns substantially as described herein and exemplified.