13 February 2022

In the Republic of Kazakhstan, a project to enlarging Aktobe CHPP is being implemented. Here, a cogeneration power unit is being created - a gas turbine unit, which will be integrated into the process flow scheme of the facility to operate in a combined cycle. The launch of the GTU is scheduled for 2022.

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 combines robust design, high efficiency and low emissions. Due to its high exhaust energy, this turbine is effectively applied in the combined cycles.

From turbine, exhausted hot gases (fuel combustion products) enter waste-heat boiler manufactured by JSC Machine-Building Factory of Podolsk, the purpose of which is 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.

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

The fuel supply for new power unit will be performed by the ENERGAS comprehensive gas treatment system which will provide the quality of gas in accordance with the pre-set 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).

Currently, the BCS has been mounted at the operation site. The installation, alignment and fixing of the equipment on the foundations have been completed, air cooling devices were built on. Assembling of large units, piping arrangement and electrical power connection are planned.



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 this purpose, 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 shell-and-tube 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.

A block-type gas treatment station has already been installed at the construction 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. In 2020, Aktobe CHPP produced 927.9 million kWh of electricity, which is more than 12% of the region's consumption. Electric and thermal capacity – 118 MW and 878 Gcal / h, respectively.

At the moment, there are six steam turbines and nine boilers installed here. The need for reconstruction and upgrade of the power plant, built in the 40s of the last century, is because some of the main and auxiliary equipment have entirely exhausted their resource.

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