Dry process kiln systems - · PDF file• Long refractory life due to low thermal kiln load and stable kiln coating. • Independent and accurate draft control for kiln and calciner

■ Highly reliable

■ Low emission levels

■ Efficient energy utilization

Dry process kiln systems

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2 · Dry process kiln systems

F.L.Smidth offers a range of six standard dry-process kiln systems, each with its unique advantages depending upon the particular application. In this way we are able to provide the industry with the most suitable kiln system configuration for any given set of conditions and requirements.

F.L.Smidth has supplied over 2500 rotary kiln systems and more than 3500 clinker coolers. This experience, coupled with the latest advances in pyroprocessing system design, makes our technology the logical choice for both new installations and mod- ernisation of existing cement making facilities.

In modern cement plants, raw meal is pre- heated to calcination temperature in a mul- ti-stage cyclone preheater and most of the calcination process takes place in a separate- ly fired calciner. The remaining calcination and clinkerization process takes place in a short length-to-diameter rotary kiln without internals.

Preference is commonly given to the cooling of clinker in the SF Cross-Bar™ cooler in which the two main functions, conveying and cooling of clinker, are completely sepa- rated. The introduction of stationary air dis- tribution plates with self-regulating mechanical flow regulators (MFR) has revo- lutionized cooler operation.

This brochure describes each of the six pre- heater/calciner system configurations in detail and presents general guidelines for their selection depending upon capacity requirements and whether the system is new or an upgrade of an existing installa- tion. System components other than cyclones and calciners are dealt with in sepa- rate brochures that describe their mechanical and operational features.

• Highly reliable systems for any production level

• A wide range of calciner systems to suit specific require- ments

• Highly efficient low pressure cyclones

• Effective emission control technology

• Optimized fuel and power consumption

• Suitable for waste fuels

• Compact, space-saving preheater designs

• Matching state-of- the-art technologies for clinkerization, cooling and firing: ROTAX-2 two-support kiln, SF Cross-Bar™ clinker cooler and Duoflex kiln burner

Main features

K I

L N

S

Y S

T E

M S

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Six standard Dry-process kiln system configurations

SP: Suspension Preheater kiln

ILC: In-Line Calciner

SLC: Separate Line Calciner

ILC-E: In-Line Calciner using Excess air

SLC-D: Separate Line Calciner – Downdraft

SLC-I: Separate Line Calciner with In-line Calciner

1349_M_FLS_DryProcessKiln 28/11/02 9:16 Side 3

-350mm WG

282° C

608° C

820° C

280° C

100° C

454° C

734° C

4 · Dry process kiln systems

Special advantages • For small capacities

– the economical solution. • Very low specific power consumption

– with planetary cooler. • Simple operation

– well suited for manual control. • Accepts higher input of chlorides than

precalcining systems with tertiary air duct (without bypass).

SP: Suspension Preheater kiln

Features • Normal capacity range: 700-4500 tpd. • Ratio of firing in riser duct: 0-15%. • Bypass of kiln gas: 0-30%. • Planetary cooler can be employed.

5-stage SP kiln system and SF Cross-Bar™ cooler Typical temperatures in the system are indicated together with the neg- ative pressure in the exhaust gas exit based on a system designed for minimum overall pressure drop. This type of kiln system can be converted to the SLC precalcining system by adding an extra calcin- ing string. If no future capacity increase is to be considered, a plane- tary cooler may be considered.

material

gas

fuel

1. Raw meal feed

2. Exhaust gas

3. Kiln gas by-pass, if any

4. Clinker

5. Kiln burner

6. Riser duct firing, if any

7. Cooler excess air

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-395mm WG 269° C

594° C

840° C

437° C

727° C

280° C

100° C

Dry process kiln systems · 5

Special advantages • Most economical solution for small and

medium capacities. • Low specific power consumption with

planetary cooler. • Easy operation due to high excess air

percentage in kiln. • Low coating tendency in kiln inlet

and riser duct. • Long kiln lining life due to stable kiln

coating. • Less sensitive to chlorides and sulphur

than precalcining systems with tertiary air duct (without bypass).

• Smaller kiln dimensions than SP system.

ILC-E: In-Line Calciner using Excess air

Features • Normal capacity range: 800-5500 tpd. • Ratio of firing in calciner: 10-25%. • Bypass of kiln gas: 0-25%. • Calcination at kiln inlet: 50-70% (com-

pared to 30-40% for SP operation). • Planetary cooler can be employed.

material

gas

fuel

1. Raw meal feed

2. Exhaust gas

3. Kiln gas by-pass, if any

4. Clinker

5. Kiln burner

6. Calciner burners

7. Cooler excess air

ILC-E kiln system with five-stage preheater and SF Cross-Bar™ cooler Typical temperatures in the system are indicat- ed, together with the negative pressure in the exhaust gas exit, based on a system designed for minimum overall pressure drop. If no future capacity increase is to be considered, a planetary cooler may be considered.

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-465mm WG 293° C

650° C

890° C

478° C

799° C

1000° C

280° C

100° C6 · Dry process kiln systems

Special advantages • High material and gas retention time in

calciner due to its large volume and moderate swirl.

• Regulation range of up to 30% bypass of kiln gas using ILC-I version.

• Well suited for low-grade fuels. • Long refractory life due to low thermal

kiln load and stable kiln coating. • Lowest NOx emission among traditional

calciner kiln systems.

ILC: In-Line Calciner

Features • Normal capacity range: 1500-6000 tpd,

with multiple strings > 10,000 tpd. • Ratio of firing in calciner: 55-65%. • Normal bypass of kiln gas: 0-60%. • Maximum bypass of kiln gas:

0-100% using ILC-I version. • Built-in low-NOx capabilities. • Calcination at kiln inlet: 90-95%.

ILC kiln system with five-stage preheater and SF Cross-Bar™ cooler Typical temperatures in the system are indicated, together with the negative pressure in the exhaust gas exit, based on a system designed for minimum over- all pressure drop. When designed for bypassing 30% or more of the kiln gases, the layout of the system will be slightly different, as the tertiary air duct is connected to the kiln riser duct at a point below the calciner. This system is called the ILC-I calciner system. (See page 13)

material

gas

fuel

1. Raw meal feed

2. Exhaust gas

3. Kiln gas by-pass, if any

4. Clinker

5. Kiln burner

6. Calciner burners

7. Tertiary air duct

8. Tertiary air duct damper

9. Cooler excess air

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-475mm WG 300° C

657° C

890° C

487° C

803° C

886- 1100° C

1000° C 280° C

100° C

Dry process kiln systems · 7

Special advantages • High material and gas retention times in

the calciner/ combustion chamber whose dimensions are minimal since the kiln gases do not pass through it.

• Very well suited for all fuel types, espe- cially low-volatile fuels, as the combustion in the calciner takes place in hot atmos- pheric air and the combustion tempera- ture in the calciner can be controlled independently of the temperature of the calcined material fed to the kiln.

• Low NOx operation is possible. • Smallest possible tower dimensions, as

the calciner can be installed separately from the cyclone tower.

• Especially well suited for retrofits of existing SP or ILC preheaters due to very short down time.

SLC-D: Separate Line Calciner – Downdraft

Features • Normal capacity range: 1500-6000 tpd,

with multiple strings > 10,000 tpd. • Firing in calciner: 55-60%. • Bypass of kiln gas: 0-60%. • Maximum bypass regulation range: 30%. • Calcination at kiln inlet: 90-95%.

SLC-D kiln system with five-stage preheater and SF Cross-Bar™ cooler Typical temperatures in the system are indicated, together with the negative pressure in the exhaust gas exit, based on a system designed for minimum overall pressure drop. For production capacities exceeding approximately 6000 tpd, the system is equipped with two or more preheater strings, this also being the case if a particu- larly low preheater tower is required.

material

gas

fuel

1. Raw meal feed

2. Exhaust gas

3. Kiln gas by-pass, if any

4. Clinker

5. Kiln burner

6. Calciner burners

7. Tertiary air duct

8. Tertiary air duct damper

9. Cooler