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At Minsk CHPP-3, the first stage of upgrade of the gas treatment and fuel supply scheme has started for the combined-cycle power unit CCGT-230

8 September 2020

Since 2009, a combined cycle gas turbine unit (CCGT-230) has been operating as part of Minsk CHPP-3 (branch of RUE Minskenergo). The power generating unit is supplied with fuel by a gas treatment system based on a booster compressor station (BCS) manufactured by VPT Kompressoren GmbH.



Gas treatment system is being upgraded (expanded) by an additional BCS supplied by ENERGAS. This BCS is made on the basis of a screw oil-filled compressor and is a block-modular process unit with a maximum integration of the components on a single frame. The station is placed in its own sound-absorbing shelter which equipped with all the necessary engineering systems, including life support systems and safety.

The new BCS is the second most powerful among all 234 gas compressor stations of screw type, put into operation by ENERGAS. The gas flow rate is 38,160 kg / h. Only BCSs for the Grozny TPP, which were launched last year, have greater capacity.

Unit compresses fuel to the required designed values (2.7 MPa) and feed it to the gas turbine of CCGT. Gas flow rate is controlled in the range from 0 to 100% of nominal. For this purpose, a special two-loop regulation system is applied. The first loop (control by the compressor spool valve) provides smooth, stepless capacity control in the range of 15 ... 100%, and to control capacity in the lower range it is combined with a gas recirculation system (second loop), which allows you to respond quickly and correctly on a sharp change in load during transient operating modes of conjugated turbine.



Fuel gas filtration system is composed of gas-oil filter separator of the 1st stage of purification and the coalescing (safety) filter of the 2nd stage. Residual content of impurities in gas at the outlet of the BCS is not more than 1 ppmw (mg / kg). A gas cooler is integrated into the process flow diagram of the compressor station, which maintains the fuel design temperature (+50°C).

For BCS pneumatic circuit, the supply set includes an auxiliary air compressor station (ACS).

The oil system of BCS uses ester synthetic oil of the new generation ESTSYN, which is specially created for units made based on screw compressors. The oil of ESTSYN CE100 brand ensures efficient operation, increases reliability and equipment life.

Gas supply scheme for the combined-cycle power unit will be also changed. Current and new BCS for fuel gas will operate alternately, evenly distributing the operational load. When one station is turned on, the second one switches to the hot-standby mode. Their own ACSs implement launch (and preparation for start), shutdown, and maintaining the optimal operation mode; they control the process parameters and gas pollution in the premises; they provide automatic protection and alarm system; they handle the parameters of the workflow and emergency events with the issuance of information.

ENERGAS equips compressor equipment with a two-tier automated control and regulation system (ACRS), which will combine local ACS of both BCS and integrate them into the automated processes control system of a facility. Remote control (operator workstation, WKS) will be located in the control room of the CCGT.



The ACRS is made on the basis of microprocessor technology using modern software and cross-connect equipment. Control from the central panel will be carried out in full, similar to the control "in site".

Before shipment, the new compressor station underwent factory testing. The process unit was delivered to the Minsk CHPP-3 site with a high degree of prefabrication what reduces the duration of pre-start activities.

Currently, the 1st stage of the project has started – erection work: installation, alignment and fixing of the BCS on the foundation, large-block assembly, mounting of air-cooling devices, piping arrangement, electrical power connection. Then the 2nd and 3rd stages will take place – "cold" adjustment and a range of own and integrated tests.

The commissioning of the BCS, VCS, and ACRS is carried out by the specialists of ServicENERGAS (part of the ENERGAS Group). Upgrade of the gas treatment system will increase the reliability of CCGT-230 fuel supply and ensure uninterrupted operation of the combined-cycle power generating unit at all modes and under any climatic conditions.



REFERENCE:

In the power grid of the Republic of Belarus, Minsk CHPP-3 has been operating since 1951. Currently, its installed capacity is 542 MW. MCHPP-3 is a part of single production and process complex for the generation, transmission and distribution of thermal and electric energy.

CCGT-230 with an electric capacity of 222 MW and a thermal capacity of 136 Gcal/h was created on the basis of the GT13E2 gas turbine (Alstom), the HRSG/DP01.1 waste heat boiler (SES ENERGY) and the T-53/67-8.0 (UTW) steam turbine. The power generating unit efficiency is 52.5%. The main and reserve fuel is natural gas.



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