Case Study on Waste Heat Recovery from Turbine Gland Steam Drain Line for Driving a Vapor Absorption Cooling System

Abstract

In thermal power plants, Vapour Absorption Machines (VAMs) are conventionally operated using Auxiliary Pressure Reducing and Desuperheating Station (APRDS) steam, resulting in losses of high-grade energy and condensate. Simultaneously, turbine gland steam drain during self gland-sealing operation is continuously discharged to the condenser to maintain required inlet temperatures, leading to additional waste of recoverable thermal energy. This study presents a Kaizen-based modification in which the turbine gland steam drain is utilized as the driving heat source for a 300 TR Vapour Absorption Machine, integrated with a condensate recovery system. The proposed system effectively harnesses low-grade waste steam for refrigeration, reduces dependence on APRDS steam, and enables condensate reuse. Integration of DCS-based control, protective interlocks, and real-time monitoring ensured safe and reliable operation. Implementation results demonstrate a coal saving of approximately 6 tons per day, along with reductions in CO? emissions, ash generation, and DM water consumption. The study confirms that turbine gland steam drain utilization offers a practical and sustainable approach for waste heat recovery in thermal power plants

Introduction

In thermal power plants, Vapour Absorption Machines (VAMs) are traditionally operated using high-grade APRDS steam, resulting in significant energy losses due to throttling and the discharge of condensate to the atmosphere. Additionally, during turbine self gland-sealing operation, high-temperature gland steam drain is continuously released to the condenser, causing further waste of recoverable thermal energy.

To address these inefficiencies, a kaizen-based modification was implemented in which the turbine gland steam drain is diverted and used as the driving heat source for the VAM, along with a condensate recovery system. In the modified system, waste heat from the gland steam drain is effectively utilized for refrigeration in the VAM generator, and the resulting condensate is recovered and returned to the plant condensate system.

The project involved steam line modifications, installation of condensate recovery equipment, conductivity monitoring, and integration of DCS-based control and protection interlocks. This ensured safe operation, condenser vacuum protection, and water quality control.

After implementation, the system demonstrated stable and reliable performance, with improved monitoring and automated control. The modification resulted in significant efficiency gains, including an estimated coal saving of about 6 tons per day, along with reductions in CO? emissions, ash generation, and demineralized water consumption. Overall, the project highlights effective waste heat utilization, energy conservation, and improved sustainability in thermal power plant operations.

Conclusion

The implementation of waste heat recovery from the turbine gland steam drain for operating the Vapour Absorption Machine, along with an integrated condensate recovery system, has demonstrated significant improvements in energy efficiency and resource conservation. The modified system enables effective utilization of low-grade steam, resulting in measurable reductions in coal consumption, CO? emissions, ash generation, and DM water usage. Integration of DCS-based control, enhanced monitoring, and protective interlocks has ensured safe, reliable, and stable operation. Overall, the proposed approach presents a practical and sustainable solution for waste heat and water recovery in thermal power plants, with potential for replication in similar installations.

Copyright

Copyright © 2026 Sunil Kumar Chaubey. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.