Quá trình đồng nhất liệu trong silo và hoạt động của chúng

Most efficient raw meal homogenizing system Beneficiation potential 10:1  High energy consumer Application limited to about 2000t vessels, thus sufficient for production lines up to 3000td High investment for new installations Material is flowing downwards to the silo outlet in funnels of much smaller dimension than sector dimensions Mixing takes place at material surface by blending material originating from different horizontal layers (i.e. material that has been ground at different time) Flow channels are located over the silo outlet

A Survey on Homogenizing and Blending

Silos and their Operation

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Raw Meal Beneficiation Learning Objectives

 Three major concepts in raw meal blending / homogenisation

 Basic concepts for kiln dust handling

 Kiln feed concepts

3 Silo Concepts for Raw Meal Beneficiation

Classification according to the kind of the working principle applied :

concept of the fully

agitated batch mixer

 Aerated gravity systems

following the concept

of a continuous blender

 Multi-pack gravity systems following the

concept of a continuous blender

Multi-Pack gravity systems

Homogenizing Silo System

Homogenizing Silo System Aeration System

Blending quadrant

Aeration air supply

Lighter material rises in homogenizing columns

Denser material moves downward

Aeration quadrant

Air cycling valve

Homogenizing Silo System Operation

Performance Diagram of Batch Type Homogenizing Silo

one batch

quality step between batches goal mean

value

Homogenizing Silo System Pros & Cons

 Most efficient raw meal homogenizing system

 Beneficiation potential 10:1

 High energy consumer

 Application limited to about 2000t vessels,

thus sufficient for production lines up to 3000t/d

 High investment for new installations

7 4

8

5

 Spider on top of silo for meal distribution

 Inverted cone concept

 empty cone (IBAU; K-P)

 center chamber (CPT)

 Extraction by pneumatic control valve

Continuous Blending Silos HGRS Silo Investigation

 Material is flowing downwards to the silo outlet in funnels of much smaller dimension than sector dimensions

 Mixing takes place at material surface by blending material originating from different horizontal layers (i.e material that has been ground at different time)

 Flow channels are located over the silo outlet

Continuous Blending Silo Design

 No of sectors: > D

 Cone/wall distance: < 2 m

 Max air pad length: < 2.5 m

 Aeration air pad width 200 mm

 Aerated bottom area: >35 %

2 6

IBAU type blending silo

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Continuous Blending Silos Operation

 Operate the silos at high filling levels

(> 75 %)

 Activate single sectors at a time rather

than two opposite sectors

 Sector activation sequence preventing

intersection of funnels at material

surface

 Min aeration air rate > 1 m3/(m2*min)

 Aeration sequence time 5 - 12 min

Continuous Blending Silo FLS-CF type blending silo

7 4

8

5

Continuous Blending Silos FLS Operation Mode

1

3

2 6

7 4

1

3

2 6

7 4

8

5

range of residual fluctuations

Continuous blending silos can not blend long term

Continuous blending silos can hardly deal with peaks in compositional fluctuation

104 102 100 98 96 94 92

104 102 100 98 96 94 92

112 110 108 106

Continuous Blending Silos Pros & Cons

meal uniformity ex raw mill

- long term fluctuations

- peak and step type disturbances

Multi-Pack Silo 7+1-Pack-Silo special application

 Subsequent filling of silo cells

 Simultaneous reclaim from all cells

 Separate chamber for kiln dust handling

 Suitable for very critical raw materials  segragation, Q controle

 Low - but fix blending efficiency depending on number of silo

 Limited beneficiation potential 3:1

 Higher Investment cost

Raw Meal Beneficiation Learning Objectives

 Three major concepts in raw meal blending / homogenisation

 Basic concepts for kiln dust handling

 Kiln feed concepts

 Separation factor

meal chemistry

Kiln Dust Handling Problems

Critical Not Critical Critical

Sf < 0.8 0.8 < Sf < 1.2 Sf > 1.2

RawMeal

m LS

dustkiln

LS LS

Sf 

Kiln Dust Handling Characteristics

kiln feed

LS recirc kiln dust 0.8 < Sf < 1.2

23

Kiln Dust Management Option 2

Sf not critical

 compositional step variations between

compound and direct kiln

operation periods

 may become excessive with out-of-range meal

Raw Meal Beneficiation Learning Objectives

 Knowledge of the three major concepts in raw meal

blending/homogenisation

 Knowledge of the basic concepts for kiln dust handling

 Knowledge of kiln feed concepts

Kiln Feed Proportioning Demands

 consistent raw meal reclaim from feed bin

 permanent gravimetric rate control

 high feed rate accuracy for a wide control range

 consistent raw meal transport to the kiln

 high operation reliability

 fully enclosed design

 reliability (low maintenance requirement)

Kiln Feed Proportioning Criteria

of kiln operation

(70 - 80 % filling)

gate

Kiln Feed Proportioning Rotor Scale

 Rotor scales proportion and weigh material and feed it by

gravimetric or pneumatic transport to the process

 Powdery to coarse and free- to difficult-flowing material can be

handled enclosed by the rotor scale

 Function principle:

The rotor scale works like a high sophisticated “circular” weigh

feeder but the belt is replaced by a rotor with cells

ANIMATION

(Animation Pfister.exe)

 Requires stable material flow

to measurement equipment

 For applications with pulverized fuel or for kiln feed only to be used with pre-bin

Agitator with

vertical rotary valve

“Multicell”

Kiln Feed Proportioning Coriolis Flow Meter

 The Coriolis Flow Meter only measures, but does not proportion the material flow Thus it is combined with a kind of extraction and flow control device as, rotary valve, throttle gate or rotary valve with

vertical axis (Schenck Multicell)

 It is suitable for fine, not sticky

wheel The angular momentum Fc

generated therewith, indicates

FR

FZ

ANNEXES