23 December 2022

The ENERGAS system, which consists of a block-type gas treatment station and a booster compressor station, provides 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, the upgrade (enlargement) of Aktobe CHPP is being completed. Here, a cogeneration power unit is being prepared for the launch – 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.

The Aktobe Central Heating and Power Plant is the only source of district heating in Aktobe, the largest city in Western Kazakhstan. Before the launch of the new power unit, the electric and thermal capacity of Aktobe CHPP is 118 MW and 878 Gcal / h, respectively.

To the fuel supply for GTU, the ENERGAS multifunctional system was installed here which ensures that the gas meets the specified parameters in terms of 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).

BGTS and BCS have been commissioned in advance by the specialists of ServicENERGAS (ENERGAS Group), what allows Kazakh power engineers to carry out a full range of tests of the generating equipment and put the new power unit into operation in a timely manner.

The block-type gas treatment station, manufactured under a special project, is used for metering, filtration and pressure reduction of gas. The throughput of the BGTS is 15,433 m3 / h – similar to the rated fuel consumption of GTU.



Process unit is equipped with separation system with a two-stage coalescing filters, the trapping of condensate and mechanical impurities occurs here in automatic mode. Gas filtration efficiency is 99.9% for particles larger than 3 microns. Subassembly for gathering and storage of purification products includes an underground drainage reservoir (storage tank) with a volume of 1 m3, a liquid level control device and equipment for removing condensate and sludge into a mobile cistern.

In situations where the pressure in the supply pipeline exceeds the design parameters, the gas flows through the reducing module. This element of BGTS guarantees a decrease and a stabilization of the pressure at a required level, as well as excludes its differences at the inlet to compressor units of the BCS.

To measure the volume of fuel entering the power generating unit, the BGTS is equipped with a two-line process gas-metering unit with a relative error of no more than 2%. Data from him is transmitted via communication channels to the upper level of the APCS.

The gas treatment station is additionally equipped with an outlet fuel quality control subassembly with measuring and analytical equipment. The BGTS is housed in a separate all-weather block-box with the integration of elements on a single frame, equipped with systems of working and emergency lighting, premise heating and ventilation, safety systems.



After preliminary treatment, the gas flow is directed to the booster compressor station. ENERGAS 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. Units 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 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 of BCS provides for the stable maintenance of the design fuel temperature. The delivery lines of the CUs are equipped with heat exchangers which cool the working medium to the level of the optimum gas supply temperature (+60°C) established by the turbine manufacturer and terms of the project.



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 and fire extinguishing systems.

Within the commissioning of the fuel gas treatment system for the new GTU of Aktobe CHPP, ENERGAS service engineers performed erection supervision, starting-up and adjustment, and testing of equipment, as well as conducted training of operational personnel.



REFERENCE:

Among the priorities of the ENERGAS Group are production, comprehensive commissioning and maintenance of gas treatment and compression units for generating facilities in the electric power industry, oil and gas complex and industrial enterprises. The ENERGAS process equipment today provides high-quality fuel for 230 gas turbines and gas-reciprocating units with a total capacity of over 6.7 GW.

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