Efficient Tunnel Boring Slurry Dewatering for Metro Construction
Skid-Mounted System with Dual LW750×3200B Decanter Centrifuges Delivers Reliable Performance for Municipal Metro Project
Project Background
A construction company was handling a municipal metro tunnel project. The tunnel boring machine (TBM) produced large volumes of slurry that needed on-site dewatering. The goal was to reduce disposal volume, meet discharge requirements, and simplify site logistics. They needed a mobile, integrated system that could handle the variable feed conditions common in TBM work.
Customer Challenges
- Large volumes of TBM slurry requiring on-site dewatering to reduce transport and disposal costs
- Variable slurry composition and feed rates depending on geological conditions and TBM operation cycles
- Limited space at construction site requiring compact, skid-mounted equipment configuration
- Need for reliable, continuous operation to keep pace with tunnel construction schedule
- Requirement for effective solid-liquid separation to meet environmental discharge standards
- Minimizing polymer consumption while achieving acceptable cake dryness for disposal
Our Solution
We reviewed the slurry properties and site constraints, then supplied a complete skid-mounted dewatering system. The package includes two LW750×3200B two-phase decanter centrifuges, feed pumps, polymer preparation and dosing systems, and controls. Everything is pre-assembled on skids, which speeds up installation and ensures proper integration.
System Components
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Decanter Centrifuges
Two LW750×3200B two-phase decanter centrifuges with 750mm bowl diameter and 3200mm length. The high G-force design effectively handles fine particles and colloidal material typical in TBM slurry, delivering clear liquid phase and consistent cake dryness.
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Feed System
One 11kW sand pump handles primary feed. Two 15kW sand pumps provide secondary feed and recirculation, maintaining steady feed pressure and flow control throughout operation.
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Polymer Dosing System
Two integrated polymer preparation and dosing skids, each with automatic preparation and precise dosing control. This setup optimizes flocculation performance while keeping chemical consumption within the 3-6 kg/T.DS range.
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Skid-Mounted Configuration
Complete system pre-assembled on two centrifuge skids. Compact footprint and straightforward installation make it well-suited for construction site deployment. Wetted parts use corrosion-resistant materials for reliable operation in construction slurry applications.
Project Overview
- Customer Industry Construction
- Application TBM Slurry Dewatering
- Equipment Model 2 × LW750×3200B
- Actual Capacity 40 m³/h per unit
- Design Capacity 40-100 m³/h per unit
- Operating Speed 2200 RPM
- Centrifugal Force 2033G
- Cake Moisture 42-45%
- Polymer Consumption 3-6 kg/T.DS
Treatment Performance
The skid-mounted system has run reliably since startup, handling TBM slurry throughout the tunnel construction. Each centrifuge processes about 40 m³/h, within the 40-100 m³/h design range. The system maintains steady operation despite the variable feed conditions typical of TBM work.
Operational Performance Metrics
- Processing Throughput: Running at 40 m³/h per unit, within the 40-100 m³/h design range. With two units, total capacity is 80 m³/h, with backup capacity for maintenance.
- Cake Moisture Content: Cake moisture stays at 42-45%, suitable for disposal or further treatment. This cuts transport volume compared to untreated slurry.
- Polymer Consumption: Polymer usage at 3-6 kg per ton of dry solids (kg/T.DS), typical for construction slurry. The integrated dosing systems help control chemical costs.
- System Reliability: Skid-mounted setup allows quick deployment and straightforward operation. Pre-assembled design cuts installation time and complexity.
- Liquid Phase Quality: Clarified liquid meets discharge requirements, suitable for disposal or reuse per local regulations.
- Operational Flexibility: Handles variable feed rates and composition changes common in TBM work, maintaining steady performance across different ground conditions.
Customer Feedback
"The skid-mounted system has worked well for our metro project. It handles the TBM slurry reliably, and the integrated design made installation simple. We're processing at higher rates than planned, which helps us keep up with construction. Cake moisture is consistent, which makes disposal easier. The system has been reliable, and the startup support was good."
— Project Manager, Construction Company
Why This Solution Works
Integrated Skid Design
All components are pre-assembled and tested on skids. This cuts installation time and ensures pumps, dosing systems, and centrifuges work together properly.
High G-Force Separation
The 2033G centrifugal force handles fine particles and colloidal material in TBM slurry. This delivers clear liquid phase and consistent cake dryness.
Capacity Margin
The wide design capacity range (40-100 m³/h) gives operators flexibility. Current operation at 40 m³/h leaves room to increase throughput when needed to match construction pace without losing separation quality.
Chemical Usage
The integrated polymer dosing systems with automatic preparation keep flocculation consistent while controlling chemical costs. The 3-6 kg/T.DS rate is reasonable for this application.
Construction Site Suitability
Skid-mounted design fits construction site needs. Compact footprint, simple installation, and robust build enable reliable operation in tough site conditions.
Dual-Unit Redundancy
Two units provide backup for maintenance and allow continuous operation. Operators can service one unit while the other runs at full load, minimizing downtime.
Project Value
This project shows how integrated skid-mounted dewatering systems work for construction applications. The solution handles TBM slurry dewatering challenges while providing operational flexibility and reliability.
Key Benefits
- Reduced slurry volume through dewatering, lowering transport and disposal costs
- On-site processing eliminates off-site treatment, improving project logistics
- Consistent cake moisture (42-45%) suitable for standard disposal methods
- High capacity (40 m³/h per unit) keeps pace with tunnel construction
- Integrated design simplifies operation and reduces installation complexity
- Reasonable polymer consumption (3-6 kg/T.DS) keeps operating costs in check
