Kiln firing with differential temperature gradients

Patent metadata

Field	Value
Publication number	US-2019017744-A1
Application number	US-201716069749-A
Country	US
Kind code	A1
Filing date	Jan 13, 2017
Priority date	Jan 15, 2016
Publication date	Jan 17, 2019
Grant date	—

Abstract

A method for heating ware in a kiln. The ware space of the kiln includes a plurality of temperature control zones oriented in a first direction, and a plurality of temperature control zones oriented in a second direction. The method includes heating the ware space in a first heating stage, a second heating stage, and a third heating stage. At least one of the following conditions is satisfied: (i) in one of the heating stages, a temperature control zone oriented in the first direction has a setpoint temperature that is different from a setpoint temperature of one other temperature control zone oriented in the first direction; and (ii) in one of the heating stages, one temperature control zone oriented in the second direction has a setpoint temperature that is different from a set point temperature of one other temperature control zone oriented in the second direction, wherein the first direction is a vertical direction and the second direction is a horizontal direction.

First claim

1 . A method for firing ware in a periodic kiln, the method comprising:
positioning at least one stack of ware in a ware space of the periodic kiln, wherein the ware space comprises a plurality of temperature control zones that are oriented in a first direction, and a plurality of temperature control zones that are oriented in a second direction; heating the ware space in a first heating stage from an ambient temperature to a first temperature that is greater than the ambient temperature; heating the ware space in a second heating stage from the first temperature to a second temperature that is greater than the first temperature; and heating the ware space in a third heating stage from the second temperature to a top soak temperature that is greater than the second temperature, wherein at least one of the following conditions is satisfied:
(i) during at least one of the first heating stage, the second heating stage, and the third heating stage, one temperature control zone of the plurality of temperature control zones that are oriented in the first direction has a setpoint temperature that is different from a setpoint temperature of at least one other temperature control zone of the plurality of temperature control zones that are oriented in the first direction; and
(ii) during at least one of the first heating stage, the second heating stage, and the third heating stage, one temperature control zone of the plurality of temperature control zones that are oriented in the second direction has a setpoint temperature that is different from a setpoint temperature of at least one other temperature control zone of the plurality of temperature control zones that are oriented in the second direction.

2 . The method of claim 1 , wherein the first direction is a vertical direction and the second direction is a horizontal direction.

3 . The method of claim 1 , wherein the plurality of temperature control zones that are oriented in the first direction comprises a first temperature control zone adjacent to a hearth of the ware space, a second temperature control zone adjacent to a crown of the ware space, and a third temperature control zone between the first temperature control zone and the second temperature control zone.

4 . The method of claim 3 , wherein during the first heating stage:
a setpoint temperature of the first temperature control zone is from about 10° C. to about 50° C. less than the setpoint temperature of the third temperature control zone; and a setpoint temperature of the second temperature control zone is from about 10° C. to about 50° C. greater than the setpoint temperature of the third temperature control zone.

5 . The method of claim 3 , wherein during the first heating stage:
a setpoint temperature of the first temperature control zone is from about 15° C. to about 30° C. less than the setpoint temperature of the third temperature control zone; and a setpoint temperature of the second temperature control zone is from about 15° C. to about 30° C. greater than the setpoint temperature of the third temperature control zone.

6 . The method of claim 1 , wherein the plurality of temperature control zones that are oriented in a second direction comprises a first temperature control zone adjacent to a front wall of the ware space and a second temperature control zone adjacent to a back wall of the ware space.

7 . The method of claim 6 , wherein during the third heating stage, a setpoint temperature of the second temperature control zone is from about 3° C. to about 20° C. greater than the setpoint temperature of the first temperature control zone.

8 . The method of claim 6 , wherein during the third heating stage, a setpoint temperature of the second temperature control zone is from about 3° C. to about 15° C. greater than the setpoint temperature of the first temperature control zone.

9 . The method of claim 1 , wherein during the second heating stage:
each temperature control zone of the plurality of temperature control zones that are oriented in the first direction has a same setpoint temperature, and each temperature control zone of the plurality of temperature control zones oriented in the second direction has a same setpoint temperature.

10 . The method of claim 1 , wherein during the second heating stage:
each temperature control zone of the plurality of temperature control zones that are oriented in the first direction has a different setpoint temperature, and each temperature control zone of the plurality of temperature control zones oriented in the second direction has a same setpoint temperature.

11 . The method of claim 1 , wherein the first temperature is from about 250° C. to about 700° C., the second temperature is from about 600° C. to about 1000° C., and the top soak temperature is from about 1200° C. to about 1550° C.

12 . The method of claim 1 , further comprising supplying a dilution gas to each of the plurality of temperature control zones that are oriented in the first direction during the first heating stage, wherein the dilution gas has a different volumetric gas flow rate at each of the plurality of temperature control zones that are oriented in the first direction.

13 . The method of claim 12 , further comprising:
measuring or calculating a VOC level in each of the plurality of temperature control zones that are oriented in the first direction during the first heating stage; supplying a largest volumetric dilution gas flow rate of the dilution gas to a temperature control zone oriented in the first direction having a highest measured or calculated VOC level; and supplying a least volumetric dilution gas flow rate to a temperature control zone oriented in the first direction having a lowest measured or calculated VOC level.

14 . A method for firing ware in a down-draft periodic kiln, the method comprising:
positioning at least one stack of ware in a ware space of the down-draft periodic kiln, wherein the ware space is defined by:
a crown;
a hearth opposite the crown;
a first sidewall spanning between the crown and the hearth;
a second sidewall opposite the first sidewall and spanning between the crown and the hearth;
a front wall bounded by the first sidewall, the second sidewall, the hearth, and the crown;
a back wall opposite the front wall and bounded by the first sidewall, the second sidewall, the hearth, and the crown;
a plurality of temperature control zones that are oriented in a vertical direction; and
a plurality of temperature control zones that are oriented in a horizontal direction;
heating the ware space in a first heating stage from an ambient temperature to a first temperature that is greater than the ambient temperature, heating the ware space in a second heating stage from the first temperature to a second temperature that is greater than the first temperature; and heating the ware space in a third heating stage from the second temperature to a top soak temperature that is greater than the second temperature, wherein at least one of the following conditions is satisfied:
(i) during at least one of the first heating stage, the second heating stage, and the third heating stage, one temperature control zone of the plurality of temperature control zones that are oriented in the vertical direction has a setpoint temperature that is different from a setpoint temperature of at least one other temperature control zone of the plurality of temperature control zones that are oriented in the vertical direction; and
(ii) during at least one of the first heating stage, the second heating stage, and the third heating stage, one temperature control zone of th

Assignees

• Corning Inc

Inventors

• Dillon Gregory Paul
• Geismar Bernd
• Gerigk Michael
• Tebo Thomas Madison

Classifications

• F27D99/0033

  using burners · CPC title

• F27D2019/0093

  Maintaining a temperature gradient · CPC title

• F27B17/0041

  specially adapted for burning bricks or pottery (F27B17/0033 takes precedence) · CPC title

• F27D2019/0034

  through control of a heating quantity such as fuel, oxidant or intensity of current · CPC title

• F27D2019/0003

  Monitoring the temperature or a characteristic of the charge and using it as a controlling value · CPC title