# US 4,391,585 A · Method of operating a continuous ceramic kiln

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- Number: US 4,391,585 A
- Document ID: US4391585A
- Status: Granted
- Kind: A
- Application number: 06/245,811
- Filed: 1981-03-20
- Granted: 1983-07-05
- Earliest claimed: 1980-03-26
- Assignees: Air Products and Chemicals, Inc.
- Inventors: Eric K. Riley; Colin D. Smith; Garry J. Yates; Norris W. Shepherd
- Web page: https://patentgrep.com/patent/US4391585A

## CPC

- F27B 9/36: Arrangements of heating devices
- C04B 33/32: Burning methods
- F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE

## Abstract

A method of operating a continuous ceramic kiln having a decarbonization zone characterized in that oxygen or oxygen enriched air is added to the decarbonization zone to maintain the average oxygen concentration in the decarbonization zone at or about a predetermined level. The predetermined level need only be adjusted for different throughputs and need not be adjusted for moderate changes in the amount of organic matter in the clay.

## Claims

### Claim 1

A method of decarbonizing shaped ceramic articles in an intermittent push continuous ceramic kiln having a heating and decarbonizing zone, a firing zone and a cooling zone fitted with means to sense the concentration of oxygen in the decarbonizing zone, said means associated with a control fitted to oxygen or oxygen enriched air injection means associated with said decarbonizing zone comprising the steps of:
progressively heating said shaped ceramic articles to about 900.degree. C. in the decarbonizing zone to oxidize organic matter contained in the articles;
maintaining the oxygen concentration of the decarbonization zone at a minimum level of 7.5% by volume between pushes as determined by the equation: ##EQU3## where C is the predetermined level at a point in the decarbonization zone;
R.sub.1 is the throughput of clayware articles during satisfactory operation of the kiln without oxygen addition;
A is the average oxygen concentration at said point during satisfactory operation of the kiln without oxygen addition at throughput rate R.sub.1 ;
R.sub.2 is the new throughput of clayware articles; and
X is between the limits of .gtoreq.0 and .ltoreq.0.5,
by adding oxygen or oxygen enriched air to the decarbonization zone;
continuing heating of said shaped ceramic articles until firing is completed; and
cooling said shaped ceramic articles to ambient temperature.

### Claim 2 (depends on 1)

A method according to claim 1, characterized in that the concentration of oxygen in the decarbonization zone is measured at a point in the decarbonization zone where the temperature is nominally between 700.degree. and 875.degree. C.

### Claim 3 (depends on 2)

A method according to claim 2, characterized in that said temperature is nominally between 750.degree. and 850.degree. C.

### Claim 4 (depends on 1)

A method according to claim 1, characterized in that the oxygen or oxygen enriched air is injected into the kiln at a position where the nominal kiln temperature is between 800.degree. and 950.degree. C. and where the injected oxygen will flow through the decarbonization zone.

### Claim 5 (depends on 1)

A method according to claim 1, characterized in that said predetermined level is between 7.5 and 11% oxygen (by volume).

### Claim 6 (depends on 5)

A method according to claim 5, characterized in that said predetermined level is between 8 and 8.5% oxygen (by volume).