In limestone-gypsum wet flue gas desulfurization (WFGD) systems of coal-fired power plants, conventional Roots blowers and centrifugal oxidation blowers present persistent operational bottlenecks, including high energy consumption, severe vibration, mechanical wear, and lubricant leakage. Executing auxiliary equipment energy-saving retrofits during scheduled unit maintenance windows—without altering existing process parameters while ensuring compliance with calcium sulfite oxidation standards in the desulfurization slurry—is a critical pathway for thermal power plants to reduce carbon emissions. Based on Greatall's field execution experience with high-voltage magnetic levitation (maglev) blowers, this paper systematically outlines the deployment workflow and key technical considerations for in-situ retrofitting.
I. Technical Concept of "In-situ Retrofitting"
In-situ retrofitting refers to an engineering methodology whereby conventional blowers are replaced directly with high-voltage maglev blowers. This approach utilizes the existing piping topology and electrical distribution infrastructure while maintaining original process parameters, such as absorber backpressure and design flow rates.
Technical Advantages: By minimizing piping reconfiguration, this methodology ensures accelerated project schedules, zero process disruption, and low systemic risk. Furthermore, the utilization of existing medium-voltage power cables significantly reduces capital expenditure (CAPEX).
II. Execution Workflow and Technical Closed-Loop
1. Precision Selection and Pre-engineering
● Operational Diagnostics: Verify the actual volumetric flow rate, discharge pressure, and operational power spectrum of the incumbent blowers.
● Boundary Auditing: Assess available spatial footprints in the blower room, verify inlet/outlet piping flange standards (GB/T or ANSI), and evaluate the capacity redundancy of the existing 6 kV high-voltage power distribution circuit. Audit Distributed Control System (DCS) I/O points to determine if additional communication cabling to the blower is required.
● Equipment Matching: Deploy Greatall high-voltage maglev blowers configured with high-efficiency permanent magnet synchronous motors (PMSM) directly coupled to the impeller. The equipment seamlessly interfaces with the original 6kV power supply system, enabling complete utilization of existing power cables and discharge headers.
2. Standardized Field Construction
Construction processes must strictly adhere to the Quality Control Plan / Inspection and Test Plan (ITP), incorporating mandatory Witness Points (W-points) and Hold Points (H-points) at critical milestones.
3. Full-Range Variable Frequency Commissioning
Upon system energization, the active magnetic bearing (AMB) control system drives the rotor into a stable, autonomous levitation state. During load commissioning, full-range variable frequency regulation technology modulates rotational speed in real time based on feedback parameters such as slurry pH and flue gas load fluctuations. This precision control minimizes non-rated power consumption while consistently maintaining desulfurization efficiency targets.
III. Key Performance Metrics (Empirical Data from Typical Power Plant Operations)
● High Energy Efficiency: Under identical oxidation process conditions, empirical field measurements demonstrate a net composite energy savings rate of 37.62%.
● Optimized O&M Experience: The system achieves oil-free operation across its entire lifecycle. Routine maintenance is confined to the periodic replacement of air intake filter elements, drastically reducing operating expenses (OPEX).
● Acoustic and Vibration Control: Compliant with ISO 14839 specifications, the active magnetic bearings support the rotor without rigid mechanical contact. This eliminates operational vibration and transmission noise, maintaining steady-state equipment noise levels at ≤80 dB(A).
● Intelligent Integrated Control: Embedded smart monitoring and fault diagnostics algorithms support seamless integration with the power plant DCS, enabling comprehensive remote parameter adjustment.
IV. Critical Risk-Mitigation Guidelines
● Environmental Compliance Threshold: Variable frequency regulation strategies must never excessively suppress volumetric flow or discharge pressure; ensuring absolute compliance with flue gas emission standards remains the primary operational constraint.
● Electrical Safety Protocols: Terminations, dielectric withstand tests (hipot testing), and commissioning of the 6kV system must strictly comply with regional Power Safety Work Regulations.
● Averting Volumetric Efficiency Losses: When utilizing existing discharge headers, non-destructive testing (NDT) for gas tightness must be performed on connection flanges and expansion joints, and seals must be replaced to prevent volumetric efficiency losses caused by air leakage.
● Operational Redundancy: Retain existing emergency bypass piping or designate a portion of the legacy blowers as hot standbys to guarantee plant production safety under extreme abnormal conditions.
Conclusion
The in-situ retrofitting of oxidation blowers represents a fundamental restructuring of auxiliary energy efficiency rather than a simple equipment replacement. Greatall’s high-voltage maglev blowers offer minimal structural modification, shortened construction periods, high energy savings, and maintenance-free operation. This technology delivers immediate economic and electrical benefits while providing a scalable, standardized model for thermal power enterprises striving to achieve decarbonization targets and energy-efficiency benchmarking for legacy assets.
