Mechanical Handling Belt conveyor Bucket elevator Apron conveyor Transfer Chutes Airassisted gravity systems Airslide Pneumatic Transport Positive negative pressure systems Fluidcon® FPipe® Mechanical Handling Belt conveyor Bucket elevator Apron conveyor Transfer Chutes Airassisted gravity systems Airslide Pneumatic Transport Positive negative pressure systems Fluidcon® FPipe®
Bulk Materials Handling Systems Technical Development Programme for Process Performance Engineers 2010 Heiko Polske HGRS/MPT-ASA © Holcim Group Support Ltd 2010 Bulk Solids Handling in Cement plants © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Terminology © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Design Considerations (1/5) Belt joint shall be vulcanized Trough angle α shall not be less than 30° Belt speed: The maximum belt speed shall not exceed 2.0 m/s Conveyors handling dry fine material (i.e cement) shall not exceed 1.25 m/s Belt speed for conveyors less than 50 meters in length shall not exceed 1.5 m/s Conveyors longer than 500 m can operate above m/s (Overland Conveyors) Trough belt width shall not be less than 800 mm For special applications 650 mm belts may be used © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Design Considerations (2/5) The minimum distance between the center of the L≥ 2xb tail end pulley and the skirt arrangement shall be larger than 2*belt width As a minimum, the skirt should not start until full troughing of belt has been achieved L Maximum conveyor slope: b Fig 1: Belt transition phase Maximum Slope Raw Material, wet Slag Clinker Cement Coal, PetCoke 16° 10° 6° 15° 6° 0° 0° 5° All sections other than loading point At loading point Fig 2: Inadequate design © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Design Considerations (3/5) Idlers: Carrier and return idler shall be designed according to DIN (15207-1 / 22107) or CEMA (Class C or greater) Carrier and return idler diameter: 100 mm for 650 to 1000 mm belts, 127 mm for belts greater than 1000 mm Carrier idler spacing shall not exceed 1250 mm for all belt widths High-density polyethylene impact bars at loading points shall be used Rubber protected impact idlers may be used, with spacing of no more than 300 mm for all belt widths Return idler spacing shall not exceed 3000 mm for all belt widths For conveyors handling sticky materials, return idlers shall be rubber disc rolls or anti-adhesive rubber tubes © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Design Considerations (4/5) Pulleys: All drive pulleys shall have rubber lagging Tail and take up pulleys: rubber lined or spiral wrapped wing pulleys Wing type pulleys without spiral are not acceptable Belt tensioning stations: For belt conveyors less than or equal to 50 m horizontal center distance, screw tensioning shall be used For belt conveyors over 50 m horizontal center distance, vertical gravity or horizontal gravity shall be used © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Design Considerations (5/5) Skirtboards and dust hood: Wear liners shall be installed to the inside and dust hoods shall not extend less than m from loading point Skirtboards shall be equipped with adjustable sealing rubber stripes or pads and shall be of the quick release type for easy adjustment Covers: Conveyors or parts thereof installed outside of buildings shall be covered For conveyors handling dry fine material (e.g cement) the lower edges of the covers must extend to 300 mm below the return belt line © Holcim Group Support Ltd 2010 PPE Course 11.05.18 / POL Belt Conveyors Belt training idlers Carrying Side Return Side © Holcim Group Support Ltd 2010 PPE Course 13 11.05.18 / POL Belt Conveyors Belt training idlers Belt trackers tied off to the supporting structure © Holcim Group Support Ltd 2010 Pivot bearing with simple O-ring seal PPE Course 14 11.05.18 / POL Belt Conveyors Belt Conveyor Incorrect design of skirtboard 180 mm Heavy dust emission in tunnel eventhough dust collectors and edge sealings are installed © Holcim Group Support Ltd 2010 PPE Course 32 11.05.18 / POL Belt Conveyors Skirtboards Skirtboard design (height) h Poor Design Good Design > Insufficent skirtboard height > Height (for fine material) should be 500 - 600 mm > Small cross-sectional area resulting in high airspeed > Cross-sectional area sufficent to achieve low airspeed inside the skirtboard © Holcim Group Support Ltd 2010 PPE Course 33 11.05.18 / POL Bucket Elevator Bucket Elevator_Tail pulley If particles get trapped between the belt and the pulley they can damage the belt (carcasse & surface) quickly > Twin opposed-cone hub with the cones base starting at the centre > Bars welded to the outer rim © Holcim Group Support Ltd 2010 PPE Course 35 11.05.18 / POL Belt Conveyors Transfer Chute Feed chute located too close to tail end (no skirtboards in transition section !) © Holcim Group Support Ltd 2010 PPE Course 36 11.05.18 / POL Pneumatic Conveying Basic principle of pneumatic conveying Positive pressure system © Holcim Group Support Ltd 2010 Negative pressure system PPE Course 46 11.05.18 / POL Pneumatic Conveying Example:Negative pressure system Vaccum cleaning systems © Holcim Group Support Ltd 2010 PPE Course 47 11.05.18 / POL Pneumatic conveying Feeder Systems Screw pump Conveying characteristic Airlock feeder Jet feeder Wide particle size distribution with fine shares Coarse and fine materials, low abrasion All materials Max throughput [t/h] approx 400 220 Max conveying distance [m] approx 1000 250 75 Max pressure difference in conveyor pipe [bar] approx 2.5 0.2 © Holcim Group Support Ltd 2010 PPE Course 48 11.05.18 / POL Pneumatic Conveyors Screw pump Material Forced in against pressure of conveying air Material Moved to Mixing Chamber Material Transported © Holcim Group Support Ltd 2010 PPE Course Material Enters Screw Conveying Air Enters Screw Pump 50 11.05.18 / POL Pneumatic Conveying Modes of pneumatic conveying 15-50 < 15 Dilute phase Low solids load ratio Medium phase Medium solids loading ratio > 50 Dense phase High solids load Conveying at low velocity Represent the majority of systems in industry Material must be capable of dense phase cov Conveying at high velocity Less abrasion Not suitable for erosive and abrasive materials Less pipeline wear Require less energy © Holcim Group Support Ltd 2010 PPE Course 51 11.05.18 / POL Pneumatic Conveying Modes of pneumatic conveying © Holcim Group Support Ltd 2010 PPE Course 52 11.05.18 / POL Pneumatic Conveying Dense phase method Supply bin Pressure vessel Filter unit Receiving bin © Holcim Group Support Ltd 2010 Dense phase conveying PPE Course 53 11.05.18 / POL Pneumatic Conveying Feeders_How to reduce energy consumption Cement Conveying: Rotary valve replaces screw pump Rotary valve Screw pump 1.5 kW 45 kW Example from: Merone Plant, Holcim Italy © Holcim Group Support Ltd 2010 PPE Course 54 11.05.18 / POL Fluidcon®/F-Pipe® Combines pneumatic and air assisted gravity conveying > Reduced specific energy consumption Feeding device Air supply (conveying) Air supply (aeration) Pipe section Pipe © Holcim Group Support Ltd 2010 PPE Course 55 11.05.18 / POL Fluidcon®/F-Pipe® Bilder aus Eclepens rein © Holcim Group Support Ltd 2010 PPE Course 56 11.05.18 / POL Fluidconđ/F-Pipeđ Fluidcon Instalation at Eclộpens plant â Holcim Group Support Ltd 2010 PPE Course 57 11.05.18 / POL ... should not start until full troughing of belt has been achieved L Maximum conveyor slope: b Fig 1: Belt transition phase Maximum Slope Raw Material, wet Slag Clinker Cement Coal, PetCoke 16°... Belt joint shall be vulcanized Trough angle α shall not be less than 30° Belt speed: The maximum belt speed shall not exceed 2.0 m/s Conveyors handling dry fine material (i.e cement) shall... PPE Course 17 11.05.18 / POL Belt Conveyors Belt Cleaner_V-Plough Idlers to keep the belt flat Flexible pressure to allow permanent contact with the belt surface © Holcim Group Support Ltd 2010