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 EBOOKBKMT.COM © Holcim Group Support Ltd CMC APAC 2009 Raw Meal Beneficiation Learning Objectives  Three major concepts in raw meal blending / homogenisation  Basic concepts for kiln dust handling  Kiln feed concepts © Holcim Group Support Ltd CMC APAC 2009 Silo Concepts for Raw Meal Beneficiation Classification according to the kind of the working principle applied : Multi-Pack gravity systems Air-fluidized systems Homogenising silo storage silo  Air-fluidized systems  Aerated gravity following the concept of the fully agitated batch mixer © Holcim Group Support Ltd systems following the concept of a continuous blender  Multi-pack gravity systems following the concept of a continuous blender CMC APAC 2009 Homogenizing Silo System Batch type, two store arrangement homogenizing silo storage silo EBOOKBKMT.COM © Holcim Group Support Ltd CMC APAC 2009 Homogenizing Silo System Aeration System Aeration air supply Lighter material rises in homogenizing columns Aeration quadrant Blending air supply Air cycling valve Blending quadrant Denser material moves downward Aeration air supply Homogenizing air supply © Holcim Group Support Ltd CMC APAC 2009 Homogenizing Silo System Operation Performance Diagram of Batch Type Homogenizing Silo 200 S [ Ca O ] 100 2.5 2.0 1.5 Start 1.0 0.5 0.4 0.3 Target 0.1 [ ] 180 160 140 120 100 80 60 40 20 Required homogenizing time [ kWh/t] 0.3 0.2 0.1 0.0 Spec energy consumption © Holcim Group Support Ltd CMC APAC 2009 concentration inlet Homogenizing Silo System Blending Efficiency Silo inlet fluctuations concentration outlet time Outlet fluctuations with a batch type homogenizing silo goal mean value time of one batch © Holcim Group Support Ltd quality step between batches time CMC APAC 2009 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 © Holcim Group Support Ltd CMC APAC 2009 Continuous Blending Silos Design concepts  Spider on top of silo for meal distribution  Inverted cone concept  empty cone (IBAU; K-P)  center chamber (CPT)  Extraction by pneumatic control valve © Holcim Group Support Ltd CMC APAC 2009 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 10 © Holcim Group Support Ltd CMC APAC 2009 Caused by:  Addition of kiln lim e s a tu r a tio n Continuous blending silos can hardly deal with peaks in compositional fluctuation SILO INLET 108 106 104 102 100 98 94 92 lim e s a tu r a tio n feeder 110 96 dust into a blending silo  Starvation of a 112 10 20 30 40 50 60 40 50 60 104 102 SILO OUTLET 100 98 96 94 92 10 20 30 time [ h ] 17 © Holcim Group Support Ltd CMC APAC 2009 Continuous Blending Silos Pros & Cons  Applicable for wide capacity ranges (5’000 – 20’000t)  Low energy consumer  Limited beneficiation potential 5:1  Decreasing beneficiation potential with increasing raw meal uniformity ex raw mill  Insufficient reduction of - long term fluctuations - peak and step type disturbances 18 © Holcim Group Support Ltd CMC APAC 2009 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 © Holcim Group Support Ltd 19 CMC APAC 2009 Raw Meal Beneficiation Learning Objectives  Three major concepts in raw meal blending / homogenisation  Basic concepts for kiln dust handling  Kiln feed concepts 20 © Holcim Group Support Ltd CMC APAC 2009 Kiln Dust Handling Problems  Separation factor   Tendency of a raw meal to cause segregation problems Indication for high deviation of kiln dust chemistry from raw meal chemistry Sf LS  LS 32 m or for existing plants LS RawMeal LSkiln dust Sf  LSkiln feed Critical Not Critical Critical Sf < 0.8 0.8 < Sf < 1.2 Sf > 1.2 21 © Holcim Group Support Ltd CMC APAC 2009 Kiln Dust Handling Characteristics Plant LS kiln feed LS recirc kiln dust 0.8 < Sf < 1.2 AL 95.7 119.5 1.25 AP 93.4 110.4 1.18 AP 93.4 110.1 1.18 AT 93.2 88.6 0.95 EC 92.1 81.3 0.88 MI 93.9 97.4 1.04 OZ 93.1 93.9 1.01 PL 90.8 70.8 0.78 UV 90.2 81.3 0.90 22 © Holcim Group Support Ltd CMC APAC 2009 Kiln Dust Handling Option  Compound operation: raw mix and kiln dust to blending silo  Direct operation: kiln dust to blending silo 23 © Holcim Group Support Ltd CMC APAC 2009 Kiln Dust Management  Compound operation: Option raw mix and kiln dust to blending silo Sf not critical  compositional  Direct operation: kiln dust to kiln feed bin step variations between compound and direct kiln operation periods  may become excessive with out-of-range meal qualities (0.8 < SF < 1.2) 24 © Holcim Group Support Ltd CMC APAC 2009 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 25 © Holcim Group Support Ltd CMC APAC 2009 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) 26 © Holcim Group Support Ltd CMC APAC 2009 Kiln Feed Proportioning Criteria Kiln feed bin  Sizing: for at least 20 of kiln operation  Installation: on load cells  Operation: at constant level (70 - 80 % filling)  Feed rate control out of blending silo: by flow control gate 27 © Holcim Group Support Ltd CMC APAC 2009 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) 28 © Holcim Group Support Ltd CMC APAC 2009 Kiln Feed Proportioning Agitator with vertical rotary valve “Multicell” Coriolis “Multicore” Coriolis Flow Meter SCHENCK  Available rates 0.5t/h - 650t/h  Turndown 1:10  Accuracy +/- 0.5%  Material properties < 5mm free/moderate flowing, noncaking  Requires stable material flow to measurement equipment  For applications with pulverized fuel or for kiln feed only to be used with pre-bin 29 © Holcim Group Support Ltd CMC APAC 2009 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 bulk materials