Process and system for reducing ringing in lime kilns

Patent metadata

Field	Value
Publication number	US-2019093950-A1
Application number	US-201816133365-A
Country	US
Kind code	A1
Filing date	Sep 17, 2018
Priority date	Sep 27, 2017
Publication date	Mar 28, 2019
Grant date	—

Abstract

This application discloses exemplary processes and systems for reducing mineral ring accumulation in calcination kiln. The processes and systems comprise inserting non-condensable gases (“NCGs”) in a preheating zone of a calcination kiln, upstream of the burner end. The pre -heating zone may be characterized by temperatures ranging from 1,300° F. to 1,750° F. The system may desirably comprise a plenum for inserting the NCGs into the rotating calcination kiln at the pre-heating zone.

First claim

What is claimed is:

1 . An elongate rotary calcination kiln system comprising:
a tubular housing having an outer shell and a refractory lining disposed within the outer shell, the refractory lining defining a kiln chamber, the kiln chamber having a burner end, a feed end distally disposed from the burner end, and a length extending between the burner end and the feed end; a plenum annularly disposed around the tubular housing, the plenum comprising a plenum housing defining a plenum chamber annularly disposed around the tubular housing, wherein the plenum chamber fluidly communicates with the chamber through an opening disposed at an insertion location, at about two thirds the length of the kiln chamber as measured from the burner end, wherein the plenum is configured to convey NCGs into the kiln chamber through the opening at the insertion location, and wherein a temperature at the insertion location is between 212° F. and 2,200° F.

2 . The system of claim 1 , wherein the insertion location is at a pre-heating zone of the kiln chamber, wherein the temperature at the insertion location is between 212° F. and 1,300° F.

3 . The system of claim 2 , further comprising a calcining zone extending from the burner zone to about 30% of the length of the chamber as measured from the burner end, wherein the pre-heating zone is disposed downstream of the calcining zone and extends about 30% to about 40% the length of the kiln chamber as measured from the burner end.

4 . The system of claim 1 , wherein the insertion location is at a calcining zone of the kiln chamber, wherein the calcining zone is disposed about 30% to about 40% the length of the kiln chamber as measured from the burner end, and wherein the temperature at the insertion location is between 1,300° F. and 2,200° F.

5 . The system of claim l further comprising a drying zone disposed about 30% of the length of the elongate rotary calcination kiln starting at the feed end.

6 . The system of claim 1 further comprising a temperature sensor disposed proximate to the insertion location.

7 . The system of claim 1 , wherein the temperature at the insertion location is between 1,300° F. and 1,750° F.

8 . The system of claim 1 , wherein the NCGs are LCHV NCGs.

9 , A process for reducing the accumulation of mid-kiln rings in an elongate rotary calcination kiln comprising:
introducing NCGs into an elongate rotary calcination kiln, at an insertion location downstream of a burner end in a kiln chamber of an elongate rotary calcination kiln, wherein a temperature of the kiln chamber at the insertion location is in a range of 217° F. to 2,200° F.

10 . The process of claim 9 further comprising not introducing the NCGs into the burner end of the elongate rotary calcination kiln.

11 . The process of claim 9 further comprising introducing a compound at the insertion location with the NCGs, wherein the compound is selected from the group consisting of: air, ammonia, a sintering agent, urea, oxygen, re-circulated flue gas, and water vapor.

12 . The process of claim 9 , wherein the temperature at the insertion location is between about 1,300° F. and about 1,750° F.

13 . The process of claim 9 further comprising measuring a first temperature at a first location upstream of the insertion location, measuring a second temperature at a second location downstream of the insertion location, comparing the first temperature to the second temperature to calculate a temperature difference adding a cooling agent with the NCGs at the insertion location when the temperature difference is less than 100° F.

14 . The process of claim 13 further comprising ceasing to add the cooling agent when the temperature difference is 100° F. or greater.

15 . A process for reducing the accumulation of kiln rings in an elongate rotary calcination kiln comprising:
feeding a calcine reactant into an elongate rotary calcination kiln at a feed end of the elongate rotary calcination kiln; oxidizing the calcine reactant in the elongate rotary calcination kiln with a burner disposed at a burner end of the elongate rotary calcination kiln, the burner end being distally disposed form the feed end; and introducing NCGs into the elongate rotary calcination kiln, through a plenum chamber annularly disposed around a tubular housing of the elongate rotary calcination kiln, wherein the plenum chamber fluidly communicates with a kiln chamber through an opening, and wherein a temperature of the kiln chamber is in a range of 1,300° F. to 1,750° F. at an insertion location.

16 . The process of claim 15 further comprising adding air, water vapor, or cooled re circulated flue gas to the plenum to control the temperature within the kiln chamber.

17 . The process of claim 15 further comprising adding urea to the plenum to reduce the amount of nitrous oxides in exhaust gases.

18 . The process of claim 8 further comprising adding water vapor to the plenum to regulate the temperature of the kiln chamber.

19 . The process of claim 15 further comprising adding both urea and ammonia and the plenum to control the amount of nitrous oxides in the exhaust gasses.

20 . The process of claim 15 further comprising measuring a first temperature at a first location upstream of the insertion location, measuring a second temperature at a second location downstream of the insertion location. comparing the first temperature to the second temperature to calculate a temperature difference, adding a cooling agent with the NCGs at the insertion location when the temperature difference is less than 100° F.

Assignees

• Andritz Inc

Inventors

• Peltonen Kimmo

Classifications

• F27B2007/367

  transversally through the wall of the drum · CPC title

• F27B7/38

  Arrangements of cooling devices · CPC title

• F27B7/362 Primary

  Introducing gas into the drum axially or through the wall · CPC title

• C04B2/005

  obtained from an industrial by-product · CPC title

• D21C11/0064

  Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor · CPC title