ANDRITZ D2LC30CNV3-PH-SA Centrifuge: Operation & Maintenance Manual

Introduction

This manual provides essential information for the safe and efficient operation, maintenance, and troubleshooting of the ANDRITZ D2LC30CNV3-PH-SA Decanting Centrifuge. It is critical for all personnel involved in the installation, operation, and maintenance of this equipment to thoroughly understand its contents.

Safety Instructions

Key Safety Guidelines:

• Maintain unobstructed access to controls and emergency stop devices.
• Guard all rotating equipment (drives, gears, fans, pumps, shafts, couplings, chains, belts, ropes).
• Lock out and secure drive motors during inspection or maintenance to prevent accidental startup.
• Ensure high-voltage and rotating electrical machinery is handled only by qualified personnel.
• Keep inlet and discharge openings connected to prevent exposure to dangerous parts.
• Warning signs must be visible and replaced if damaged.
• Do not bypass, dismantle, or shut down safety devices.
• Power down the centrifuge and all peripheral equipment before any intervention or repair work.
• Ground the machine to prevent electrostatic events.
• Never wash electronic equipment with liquid unless designed for it, or while powered on.
• Personnel with medical electronic equipment (pacemakers) are restricted from magnetic danger zones.
• Do not attempt to dismantle or repair the machine until it has completely stopped and power is off.
• Heavy repairs and modifications require prior written consent from ANDRITZ.
• Wear appropriate personal protective equipment (gloves, safety glasses, helmets, overalls) during maintenance and sample taking.

Equipment Overview

The ANDRITZ decanting centrifuge is designed for automatic solid-liquid separation. It consists of a cylindrical bowl, a cone-shaped bowl, and a scroll that extracts solids via centrifugal force. The bowl and scroll are driven by separate motors and gear reducers (Cyclo and Redex) to maintain precise differential speeds for optimal separation.

Technical Specifications:

• Model: D2LC30CNV3-PH-SA
• Feed Product: Chocolate from raw cocoa bean
• Solids Concentration: 15% to 20% TSS
• Feed Rate: 5-10 gpm
• Operating Cycle: 6 hr/day, 6 days/week
• pH Range: 4 to 7
• Nominal Bowl Speed: 4,000 rpm (Max safety: 5,000 rpm)
• Variable Relative Speed: 5 to 10 rpm
• Materials: Stainless steel 316L (bowls, scroll), 304L (frame, covers), Viton (seals). Wear protection includes tungsten carbide tiles.
• Weight: 2,072.34 lbs (940 kgs) entire unit
• Noise Level: 80 dB (A) at nominal speed (empty, 4 feet).

Operation Principles

Optimal centrifuge operation involves balancing several key parameters: bowl speed (absolute speed), liquid ring radial depth (pond depth), and relative speed (differential speed between scroll and bowl), and scroll torque setting. These adjustments are crucial for achieving desired product clarification and dryness without mechanical issues.

Key Adjustments:

• Bowl Speed: Higher speed generally leads to faster particle settling, increased throughput, and drier cake, but risks increased torque, vibration, and noise. Never exceed the maximum speed indicated on the nameplate.
• Liquid Ring (Pond Depth): Controlled by adjustable weir plates at the water exit. Lower liquid levels (larger openings) yield drier product but may increase scroll torque and decrease clarification. Higher liquid levels (smaller openings) provide clearer product but potentially wetter output. Adjustment requires centrifuge stop and power cut-off.
• Relative Speed (RS): The differential speed between the scroll and the bowl. It is adjusted via the operator interface terminal (OIT). Low RS is suitable for lightly loaded products, while high RS is for heavily loaded products. It impacts dryness, torque, and clarification.
• Scroll Torque: Monitored and adjusted for optimal product output and to prevent clogging.

Centrifuge Control System:

The Centrifuge Control Panel (CCP) houses the PLC, VFDs, and OIT for system monitoring and control. Operating modes include Manual, Auto, and Clean-In-Place (CIP). The OIT provides various screens for status indicators, setpoint entry, and alarm monitoring.

Maintenance & Troubleshooting

Regular maintenance is essential for the centrifuge's design life and performance. This includes daily checks for cleanliness, vibration, bearing noise, temperatures, and leaks. Periodic maintenance tasks, detailed in tables, cover belt tensioning, lubrication, and inspection/replacement of worn parts (e.g., nozzles, disks, protection plates).

Common Issues & Remedies:

• Vibrations: Can be caused by product silting, worn scroll/bearings, loose weir plates, or damaged shock absorbers. Requires immediate shutdown and investigation.
• Noise: May indicate increased absolute speed, worn bearings/shock absorbers, or loose screws.
• Overheating: Often due to permanent high torque, inadequate grease, incorrect lubricant level, or worn Cyclo reducer.
• Abnormal Motor Loads: Can result from accelerated bowl speed, increased extraction torque, damaged bearings, or blocked centrate outlet.
• Poor Product Clarification/Dryness: May stem from worn scroll, damaged seals, silted parts, or incorrect speed/level adjustments.
• Poor Solid Product Extraction: Possible causes include feed pump blockage, loose belts, or scroll silt.

Cleaning Procedures:

Clearing Clogging: Involves a maintenance cleanout by reversing the scroll, followed by running the centrifuge until clean water is discharged. This is typically done via the operator panel.

Cleaning In Place (CIP): A procedure to wash the rotor without disassembly using chemical agents (e.g., nitric acid, diluted soda) and hot water. Cycles can vary (36, 48, or 72 hours) and typically last about 1 hour.

Lubrication:

Proper lubrication is crucial. Regular grease injection for pillow block bearings (AGRO EP2) and scroll thrust bearings, and grease replacement for the Cyclo reducer (BP Energrease LS EP 0) are detailed. Over-greasing can cause overheating.

Disassembly & Reassembly

Detailed instructions are provided for disassembling and reassembling major components like the front/rear pillow blocks, front hub, thrust bearing, scroll, bowl plate, and Cyclo reducer. These complex procedures should only be performed by skilled personnel, ideally under the supervision of an ANDRITZ field service technician, to avoid damage and ensure warranty validity. Strict cleanliness and proper torque values are emphasized.

Tools & Parts

A list of specialized tools (e.g., elastic ring extractor, bearing extractor, scroll spreader bar) and recommended spare parts (lubricants, V-belts, seals, bearings) for the D2L centrifuge is provided to ensure continuous operation and efficient maintenance.