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Modernization of turbine unit TG3 with new back-pressure turbine at Sofia East TPP


  • Employer:
    Toplofikacia sofia ead
  • Implementation period:
    february 2019 – june 2022


The modernization with a new backpressure turbine and generator replaces the existing TG 3 at Sofia East TPP, decommissioned in 1999. The goal of the modernization is to assure the basic heating loads of the thermal power plant (TPP) as well as co-generation of electricity throughout the year for the purpose of increased energy efficiency.

The steam turbine is of backpressure type with a heat exchanger-condenser and with controlled steam extraction of 0.78 – 1.28 МРа for the thermal power plant loads. The limiting summer heat loads of the district heating system determine the turbine loading and its energy efficiency.

The turbine, the generator and the auxiliary equipment are new, based on state-of-the-art design, with high efficiency and high operational reliability, with operational lifetime exceeding 25 years.


The main Contractor to the Employer Toplofikacia EAD is Siemens Energy EOOD. GCR is a subcontractor to Siemens with overall responsibility over the design. In particular, the scope of GCR includes:

  • Development of Technical Design for parts:
    • Machinery and Technology;
    • Electrical;
    • I&C and automation;
    • Civil and Construction;
    • Health and Safety Plan;
    • Fire Safety;
    • Design for Organization and Execution of Construction;
    • Construction Waste Management Plan.
  • Development of Detailed Design covering all of the above parts.
  • Designer’s supervision and implementation of necessary changes during construction and installation works.
  • Development of As-built drawings and design documentation following completion of construction and installation works.


Technical and Detailed Design documentation have been developed, submitted and accepted by the Employer. Construction and installation works and concurrent Designer’s supervision is ongoing.