30 September 2022

The ENERGAS process system comprises a block-type gas treatment station and a compressor station consisting of two gas-booster units. Start-up and adjustment works are carried out by specialists of the ServicENERGAS (ENERGAS Group).



In the Republic of Kazakhstan, Aktobe CHPP is being enlarged. Here, a cogeneration power unit is being created - a gas turbine unit (GTU), which is 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).



The BGTS, manufactured by ENERGAS under a special project, is intended for metering, filtration and pressure reduction of gas. The throughput of the station 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.

If the pressure in the supply pipeline is higher than the design parameters, then the gas flows through the reducing module. This element of BGTS guarantees a decrease and a stable maintenance 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 ENERGAS BCS, which 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 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.



Gas treatment station and compressor station are fully automated. Their control systems are made based on microprocessor technology, using modern software, switching equipment and communication channels and protocols. The local ACSs are integrated with the facility's APCS. They provide remote control of units, automatic protections and alarm; monitor the process parameters and indoor gas hazard; handle the parameters of the workflows and emergency events; issue information to the operator panel.

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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