Driven by global "Dual Carbon" goals, the thermal power industry is facing unprecedented pressure to reduce energy consumption and emissions. The condenser vacuum system is a critical link affecting the thermal efficiency of the unit; its performance directly determines the coal consumption and emission levels of the power plant. Traditional single-stage water ring vacuum pumps have struggled to meet the demands of modern power plants for high efficiency, intelligence, and green operation due to limitations in ultimate vacuum levels, energy control, and operational stability. This article explores the large-scale application and energy efficiency innovation of vacuum pump solutions featuring the NASH TC-7 in a 300MW unit.

Project Background and Challenges

The project focuses on a 300MW subcritical unit at a major energy group's thermal power plant. The condenser's design back pressure is 6.9kPa. Previously, the system utilized three 2BE1 series single-stage water ring vacuum pumps (2 in operation, 1 standby). However, several critical issues emerged over time:

• High Energy Consumption: Single pump power was 110kW, leading to an annual consumption of approximately 2.475 million kWh.
• Insufficient Vacuum: During high-temperature summer conditions, the vacuum could only be maintained at -88kPa, limiting unit output.
• Poor Reliability: Frequent cavitation caused the impeller life to drop below one year, with an average of three unplanned shutdowns annually.
• Outdated Control: Manual switching and lack of remote monitoring led to delayed responses.

The Solution: 5-Unit NASH TC-7 Parallel Intelligent System

To address these challenges, the plant implemented a system of five NASH TC-7 double-stage liquid ring vacuum pumps in an N+2 redundancy configuration (3 running, 2 standby). This setup is integrated with industrial vacuum systems technology, including plate heat exchangers, automatic blowdown gas-water separators, and an intelligent PLC control cabinet.

Technical Advantages of NASH TC-7

The NASH TC-7 stands out due to its double-stage compression structure, achieving a much lower ultimate vacuum of 20mbar abs compared to the 33mbar of single-stage pumps. Constructed from 316L stainless steel, it offers superior resistance to trace chloride ions and solvent vapor corrosion. The optimized flow channel design increases efficiency by 15% and reduces NPSHr to 1.8m, providing robust anti-cavitation capabilities. For those seeking high-performance liquid ring vacuum pumps, this model represents the pinnacle of reliability.

Performance Comparison Table

Implementation and Intelligent Control

The implementation phase (May 2023 – August 2023) involved foundation reconstruction with vibration reduction, optimized "ring main + branch" piping layouts, and the installation of variable frequency drives (VFD). The intelligent control system now allows for:

• Automatic Load Matching: Adjusting speed based on vacuum demand for soft starts and energy saving.
• Smart Interlocking: Automatically starting standby pumps if the vacuum drops below -88kPa.
• Rotation Mechanism: Rotating the lead pump every 72 hours to equalize equipment wear, which is a best practice in vacuum pump maintenance.
• Remote Monitoring: Full integration with the DCS for real-time CRT display of status and fault self-diagnosis.

Operational Results and Economic Analysis

Following a full year of operation (Sept 2023 – Aug 2024), the data confirms a transformative impact. The average vacuum improvement of 2.8kPa translates to a coal consumption reduction of 3.08g/kWh. Economically, the system saves approximately 540,000 RMB in electricity costs annually, with an investment recovery period of just 2.8 years. Environmentally, the project reduces CO2 emissions by about 7,000 tons per year and lowers site noise from 85dB to 72dB.