Relationship Between the Condensing System of a Cement Plant Waste Heat Power Generation Turbine and Liquid Ring Vacuum Pump

Operating Process of the Turbine Condensing System in Cement Plant Waste Heat Power Generation

Cement Kiln Waste Heat Power Generation Process:

High-temperature flue gas from the cement kiln → Waste heat boiler → High-pressure steam → Steam turbine → Condenser → Condensate → Boiler circulation

Detailed process: High-temperature flue gas generated by the cement kiln preheater (PH) and clinker cooler (AQC) enters the waste heat boiler. The heat in the flue gas heats the feedwater; once it reaches the boiling point, it becomes steam. High-temperature, high-pressure steam enters the turbine, where it drives the blades and generator to produce electricity. After multistage expansion, the steam pressure and temperature decrease, producing low-pressure exhaust steam. A condenser at the turbine outlet recondenses the steam into water for return to the boiler.

Why Does a Condenser Need a Vacuum Pump?

1. Turbine efficiency is directly related to the condenser. If the turbine exhaust pressure approaches standard atmospheric pressure, there is less room for the steam to expand, reducing the turbine’s power output and electrical generation. The condenser must therefore be kept under negative pressure. The higher the vacuum level, the higher the turbine efficiency.
2. The turbine and condenser are not perfectly sealed. Air can enter through flanges, valves, and sealing structures. Excessive air reduces heat-transfer efficiency, raises turbine back pressure, and destroys the vacuum.
3. The gases entering the condenser include not only air but also other non-condensable gases. These gases cannot be liquefied; if they are not removed, they coat the heat-exchange tube surfaces, reducing steam-condensation efficiency and, consequently, power-generation efficiency.
4. Vacuum must be established quickly during startup. The condenser is initially at atmospheric pressure, and the vacuum pump must first reduce its internal pressure to a low-pressure level before the turbine can be started.
5. Vacuum System Configuration for Cement Plant Waste Heat Power Generation

Vacuum System Configuration for Cement Plant Waste Heat Power Generation

To ensure stable condenser vacuum and allow the liquid-ring vacuum pumps to undergo scheduled maintenance, two liquid-ring vacuum pumps are recommended in parallel, with one operating and one on standby. To maintain the vacuum, a complete centralized vacuum system has been designed for the customer.

Key advantages:

1. Automatic start/stop: The vacuum pumps are automatically started, stopped, and speed-controlled by variable-frequency control according to the vacuum level.
2. Stable vacuum: A target vacuum range can be set and adjusted according to actual operating conditions.
3. Unattended operation: The entire system can be automatically controlled without manual intervention, and the vacuum system can be automatically isolated during a power outage.

Conclusion

The cement industry is typically energy-intensive, and clinker production generates large volumes of high-temperature flue gas. Direct discharge not only wastes energy but also increases environmental pressure. Therefore, cement kiln waste heat recovery power generation (WHRPG) has become an important energy-saving and consumption-reduction technology for large cement plants worldwide. FORYOU Vacuum Pump has also designed customized vacuum solutions for cement plants in other countries. Contact FORYOU Vacuum Pump for your tailored vacuum solution.