11 September 2022

This process equipment is part of the ENERGAS comprehensive gas treatment system which will provide the Siemens SGT-800 turbine with fuel with specified design parameters in terms of purity, temperature, pressure and flow rate.



In the Republic of Kazakhstan, Aktobe CHPP is being enlarged. Here, a cogeneration power unit has been created - a gas turbine unit (GTU), integrated into the process flow scheme of the facility to operate in a combined cycle.

The main generation will be provided by a Siemens SGT-800 industrial gas turbine with generator with an electric capacity of 50 MW. The SGT-800 turbine combines robust design, high efficiency and low emissions. Due to its high exhaust energy, it is effectively applied in the combined cycles.

From turbine, exhausted hot gases (fuel combustion products) will flow into the waste-heat boiler manufactured by JSC Machine-Building Factory of Podolsk to generate steam with a pressure of 3.0 MPa and a temperature of 420°C in an amount of 70 tons per hour. The resulting superheated vapour of medium pressure is sent to the existing steam turbines of Aktobe CHPP for secondary electricity generation.

Thereby, the use of combined cycle technology gives the combined energy generation and maximum fuel effectiveness, increases the environmental friendliness and efficiency of the power plant. The designed capacity of the GTU is 57 MW.

To the fuel supply for new power unit, the ENERGAS comprehensive gas treatment system has been installed here which will provide the quality of gas in accordance with the specified parameters for purity, temperature, pressure and flow rate. The main elements of this system are a block-type gas treatment station (BGTS) and booster compressor station (BCS).

At present, adjustment works are underway at the BCS. Pre-start activities will be completed with own (individual) testing and integrated tests of the station as part of the power unit.



BCS consists of two packaged compressor units (CU) intended to compress and feed fuel to the GTU turbine at a pressure of 3.1 MPa. Gas-booster units will operate in 1+1 mode (one machine in operation, other in the hot-standby).

Both CUs made based on screw oil-filled compressors with a volume capacity of 12,000 kg / h each. The actual gas flow rate depends on the dynamics of the GTU load and is controlled in the range from 0 to 100% of nominal. For control, a special two-circuit regulation system is applied.

The process flow scheme provides for the stable maintenance of the calculated fuel temperature. The delivery lines of the CUs are equipped with a heat exchangers which cool the working medium and ensure the optimum gas supply temperature (+60°C) set by the turbine manufacturer (Siemens) and design requirements.

Taking into account the stringent requirements for the purity of fuel gas, the basic filtration system of the BCS, consisting of coalescing filters-separators of the 1st and 2nd stages of purification, is enhanced due additional elements: 1) the suction line of each compressor unit is equipped with a protective strainer and a highly efficient filter-scrubber; 2) safety filters for fine purification of gas are built into CU modules. As a result, the content of impurities in the fuel at the inlet to the GTU shut-off valve block does not exceed 0.1 ppmw (mg / kg).



Gas-booster units are fully automated, housed in their own shelters of container type, equipped with life support systems. According to safety requirements, CUs are equipped with fire detection, gas detection, alarm systems, fire-extinguishing systems.

Simultaneously with the adjustment of the compressor station, the block-type gas treatment station is being prepared for operation at the site of the gas-turbine power unit. The ENERGAS BGTS with a throughput of 15,433 m3 / h is intended to measure the volume, filter, reduce and stabilize the pressure of fuel before it is fed to the BCS and then to the SGT-800 turbine.

This process unit is equipped with a separation system with two-stage coalescing filters, a subassembly for gathering and storage of purification products with underground drainage tank, a reduction module, a process gas-metering unit and a fuel quality control subassembly.



Comprehensive commissioning of the gas treatment and fuel supply system for the new GTU at Aktobe CHPP – erection supervision, starting-up and adjustment, own and integrated tests as well as training of operational personnel are carried out by the specialists of ServicENERGAS (ENERGAS Group).

REFERENCE:

The Aktobe Central Heating and Power Plant is the only source of district heating in Aktobe, the largest city in Western Kazakhstan. Electric and thermal capacity – 118 MW and 878 Gcal / h, respectively.

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