During subway tunnel excavation, the shield tunneling machine acts as a giant underground steel dragon, while its hydraulic system serves as the heart and blood vessel, driving core movements including cutter head rotation and thrust cylinder expansion and contraction. For shield machines capable of continuous excavation up to 160 meters, the stable operation of the ground-mounted hydraulic system directly determines construction progress and operational safety. Statistics indicate that 70% to 80% of hydraulic system failures stem from oil contamination. Pollutants such as metal abrasive particles, moisture and oxidized colloid will cause valve sticking, pump wear and seal failure, leading to unexpected shutdown maintenance in mild cases and potential safety accidents in severe cases.
The electro-adsorption purification and regeneration technology and equipment developed by Qingdao Haina Energy Environmental Protection Technology Development Co., Ltd. deliver an effective on-line purification solution for shield machine hydraulic systems, maintaining optimal equipment performance throughout the 160-meter excavation cycle.
I. Hidden Hazards Facing Ground-mounted Hydraulic Systems
Though installed on the ground, the hydraulic system of shield machines confronts multiple contamination risks:
- Solid particle pollution: Metal abrasive particles (5-200μm) generated during hydraulic oil circulation and aging seal debris aggravate component wear and reduce system efficiency.
- Moisture intrusion: Humid underground construction environment allows moisture to enter the system through breather caps, resulting in oil emulsification and additive deterioration.
- Oxidative deterioration: Hydraulic oil tends to oxidize under high pressure and produces colloid and sludge, clogging filters and control oil circuits.
- Continuous operation pressure: Traditional offline purification requires machine shutdown during non-stop 160-meter excavation, severely hindering construction progress.
II. Haina Electro-adsorption: Core On-line Purification Technology
Breaking the limitations of conventional filtration, Haina electro-adsorption technology adopts physical on-line purification without chemical additives or changes to oil properties, realizing non-stop and high-precision purification.
- Technical PrincipleA strong electrostatic field is formed between special electrode plates driven by high voltage electric field. Contaminated oil flows through the field, and pollutants move directionally under Coulomb force and get captured by adsorption materials. The system simultaneously removes 0.1μm fine solid particles, moisture (≤0.03%) and oxidized colloid, bringing oil cleanliness up to NAS Class 6-8.
- Adaptive DesignCustomized for ground hydraulic systems of shield machines, the modular equipment covers an area less than 1 square meter and can be quickly connected to hydraulic circuits to achieve 24-hour uninterrupted purification. The intelligent control system monitors oil cleanliness in real time and automatically adjusts electric field strength to guarantee stable purification efficiency.
III. Reliable Safeguard for 160-meter Continuous Excavation
Haina on-line electro-adsorption purification system provides three-layer protection for steady 160-meter excavation:
- Trouble-free continuous operation: Eliminates over 99% of pollutants in hydraulic oil, preventing valve sticking and pump wear and ensuring stable excavation.
- Extended service life of components: Reduces abrasion on hydraulic parts, doubling or tripling the service life of key components like pumps and valves and cutting maintenance costs.
- Improved construction efficiency: No shutdown is required for filter replacement, saving 3 to 5 days of downtime within the 160-meter excavation period and greatly accelerating project progress.
Every meter of subway tunnel excavation matters to efficiency and safety. Featuring innovative on-line purification, Haina electro-adsorption technology eliminates oil contamination troubles for shield machine hydraulic systems, supplies clean power for tunneling construction, and boosts the development of urban underground transportation networks
