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Comprehensive treatment of fuel gas for the Pregolskaya TPP turbines

Using the example of the Pregolskaya TPP commissioned in March 2019, we consider the possibilities of integrated gas treatment based on multifunctional process units used in the automated process of purification, drying, heating, reducing, metering, quality control, compressing and supplying fuel gas to turbines of combined cycle power units.



NEW GENERATION

We will turn the historical clock back on six years. At that time, after the "blackout" of 2013, on the instructions of the President of Russia and in accordance with the instructions of the Government of the Russian Federation, it was decided to guarantee the necessary power capacities and securely de-risk the power-supply system of the Kaliningrad Region.

To solve this strategic task, there was created Kaliningrad Generation LLC. The project investor was Rosneftegaz JSC with an investment of 100 billion rubles. The project operators were the companies of the Inter RAO Group, which will operate the new thermal power plants.

According to the project, until 2021, it was required to build four power plants with a total installed capacity of about 1 GW – in Gusev (Mayakovskaya TPP), Sovetsk (Talakhovskaya TPP), Kaliningrad (Pregolskaya TPP) and Svetlovsk urban district (Primorskaya TPP).

Already in March 2018, with the participation of the President of Russia V.V. Putin, there were launched Mayakovskaya and Talakhovskaya TPPs, 156 MW each.



The Primorskaya TPP (195 MW) is planned to be commissioned in the third quarter of 2020 as a standby source of power supply for the region. It will operate on coal, unlike other power plants that use natural gas.

Add to this that the construction and the phased commissioning of new plants were accompanied by a large-scale upgrade of the gas transmission system and the electricity supply network using the technology of "smart grids".

All new TPPs in aggregate ensure the reliability and maneuverability of the Kaliningrad power system. The launch of the Pregolskaya TPP created the main power reserve for enforcing the economic development of the region. It is assumed that the region’s energy sovereignty will take place fully with the commissioning of the standby Primorskaya TPP.



IMPORT SUBSTITUTION IN ACTION

Pregolskaya thermal power plant with a capacity of 455.2 MW is the largest facility of the new Kaliningrad generating. The customer of this construction is Kaliningrad Generation LLC, a joint venture of PJSC Inter RAO and Rosneftegaz JSC. Inter RAO-Power Generation Management led the construction. General Contractor is Inter RAO-Engineering.

All the main equipment of the Pregolskaya TPP is produced by domestic enterprises. The station consists of four combined-cycle units with a capacity of 113.8 MW each.



Each power generating unit includes a gas turbine type 6F.03 (Russian Gas Turbines LLC, Rybinsk, Yaroslavl Region), a generator (SPA Elsib, Novosibirsk), a steam turbine (Power Machines PJSC, Kaluga), a waste-heat boiler (Machine-Building Factory of Podolsk JSC, Podolsk, Moscow Region).

Dry ventilation cooling towers are used at the facility. The construction also used technologies and solutions that reduce permissible levels of harmful emissions into the atmosphere.

The main fuel for the plant is natural gas and the standby is diesel. Combine-cycle technologies here confirm their high efficiency. Electric efficiency is 51.8%, the specific consumption of fuel equivalent to generate electricity – 236.8 grams of fuel equivalent per 1 kWh.



COMPREHENSIVE GAS TREATMENT

The fuel supply to the power units of the Pregolskaya TPP is provided by the ENERGAS comprehensive gas treatment system, which includes a multipackaged gas treatment unit, a booster compressor station of four units and a control module.

The system is installed on the territory of the Kaliningrad CHPP-2, with which the constructed power plant is adjacent. All equipment was delivered with the maximum prefabrication level (availability factor of 0.98). The coefficient of technical use is 0.92+; coefficient of reliability of starts is 0.95+. Estimated service life of the system is at least 25 years.

Gas treatment unit

The gas treatment unit (GTU) was manufactured by ENERGAS under a special project. This is a process unit consisting of several block-boxes with equipment for various purposes, which are joined in a single building with a common roof during installation. The exceptions are the inlet filtration module and the condensate drainage unit, which are externally mounted on an open frame.

The inlet module consists of three lines with coarse gas filters. The degree of purification is 99.98% for impurities over 10 microns in size. After pre-filtering, the fuel gas enters the fine purification system.

Three-line system with coalescing filter-separators provides additional removal of solid particles and separation of condensed moisture.

The gathering of gas condensate and mechanical impurities occurs automatically. Due to the climatic conditions, the drainage tank with a volume of 10 m3 is above ground. The drainage unit is equipped with electrical heating, a liquid level control device and equipment for removing condensate in a mobile vessel.



To measure the volume of gas entering the power generating units of the plant, the GTU is equipped with a commercial gas-metering unit, which includes three lines of normal flow and one line of low flow. Type of primary flow transducers (flow meters) is ultrasonic. The relative error of the metering unit is no more than 1%. Data from him is transmitted via communication channels to the gas metering station of the Kaliningrad CHPP-2, as well as to the resource accounting system and to the software and hardware complex of the automated control system of the Pregolskaya TPP.

The GTU gas-metering unit allows mutual financial calculations between the supplier, the gas distribution company and the consumer, control over the flow rates and hydraulic modes of gas supply systems, compilation of gas reception and supply balances, control over gas use efficiency.

The gas treatment unit is equipped with a quality control unit, which is based on a continuous flow gas chromatograph (calorimeter) with a sampling device. The functionality of this equipment: the determination of the composition of gas, the measurement of calorific value, the calculation of the density and relative density, the calculation of the Wobbe index.

After filtration and metering, gas enters a three-line preheating unit based on shell-and-tube heat exchangers with coaxial tubes. The rated gas flow through one heater is 53,000 m3 / h. Delivery water is used as the heat transfer agent. Here, gas is heated to the indices necessary for the normal operation of turbines. The optimal range of gas supply temperature set by the manufacturer of gas turbine units is +11 ... +40°C (extended range +11 ... +90°C).



Design gas pressure at the inlet to GTU is up to 4.14 MPa. Its reduction to the operating parameters of the feed to the turbines (2.6 ... 3.08 MPa, the maximum allowable – 3.45 MPa) is provided by the reduction system. It provides three lines of reduction – two working at 50% of the flow and one backup.

Ultimately, the gas treatment unit feeds fuel gas to the shut-off valve blocks of the gas turbine unit with a maximum capacity of 106,000 Nm3 / h.

During periods when the pressure of gas entering the GTU is insufficient for gas turbine unit operation (below 2.6 MPa), gas after filtration and metering, bypassing the preheating unit and the reduction system, is sent to a booster compressor station, where it is compressed to the required parameters.

Booster compressor station

BCS of the ENERGAS Company consists of four modular compressor units (3 in operation, 1 in a hot standby). CUs are made based on screw oil-filled compressors. The pressure in the discharge line can be provided in the range of 2.6 ... 3.45 MPa.



The unit capacity of CU is 35,500 Nm3 / h. Gas flow rate is controlled in the range from 0 to 100% of nominal. For this purpose, a special two-tier regulation system is applied.

The first tier (control by the compressor slide valve) provides smooth, stepless capacity control in the range of 15-30% ... 100%, and to control capacity in the lower range it is combined with a gas recirculation system (second tier), which allows you to respond quickly and correctly on a sharp change in load during transient operating modes of conjugated turbines.

This method of CU capacity control has several significant advantages:
  • Control system automatically sets the load depending on gas pressure in the supply line, which allows the units to operate in conditions where the pressure and flow rate of inlet gas can vary;
  • With a decrease in capacity, the power consumption of the engine is proportionally reduced, and the consumption of electricity for own needs of CU is reduced;
  • Process is fully automated and does not require the participation of operating personnel in the regulation of equipment operation.
Taking into account the stringent requirements for the purity of fuel gas, filtration system in units is enhanced. In addition to the gas-oil filter separator of the 1st stage of purification and the coalescing filter of the 2nd stage, an additional (safety) filter for fine purification of gas is built into each block-module.

The content of oil aerosols in gas at the outlet of the CU is not more than 0.5 ppm. To monitor this indicator, an oil vapor content analyzer is installed on the common exhaust manifold of the compressor station.



A cascade of successive gas coolers and gas heaters is integrated into the process flow diagram of the CU, which ensures the separation of the condensate and the stable maintenance of the designed fuel temperature for turbines of power generating units (up to +90°C).

Units are located in their own all-weather shelters of container type, equipped with life support systems (heating, ventilation, and lighting). According to safety requirements, each CU is equipped with fire detection, gas detection, alarm systems, fire-extinguishing systems.

Local ACS control module

Gas treatment unit and booster compressor units are fully automated. Their automated control systems implement launch (and preparation for start), shutdown, and maintaining the optimal operation mode; they control the process parameters; they provide automatic protection and alarm system; they handle the parameters of the workflow and emergency events with the issuance of information via a standard exchange protocol.

The local ACSs of the GTU and BCS are located in the common control module (in a separate shelter), which is located on the gas facilities site in the immediate vicinity of the GTU. The module is based on modern microprocessor technology, using advanced software and switching equipment.



The main components of the GTU ACS have redundancy, so that the failure of any of them does not lead to the shutdown of the gas treatment unit. The redundancy of the BCS ACS elements was not performed, since the reliability of operation of the compressor units is guaranteed by the availability of a standby CU.

In the absence of internal power supply, its own uninterruptible power supplies ensure autonomous operation of the software and hardware complex of the GTU ACS for at least 1 hour, and the BCS ACS – at least 0.5 hours.

The module is integrated with the upper level of the APCS. It provides remote control of equipment, gas pollution control in the premises, output of information on the status of elements and components to the operator panel. Control from the control module of the power plant is carried out in full, similar to the control "in site".

INCREASE OF EXPERIENCE

The engineering supervision works for commissioning the gas treatment and gas supply system at the Pregolskaya TPP were performed by the specialists of LLC ServicENERGAS (part of the ENERGAS group of companies).

This project is another example of the creative combination of the ENERGAS Group's long-term experience with innovative technical solutions. This is a significant stage in the work of designers and engineers of ENERGAS to increase the efficiency and reliability of gas-treatment and gas-feeding process equipment. This equipment is designed for large power plants, small energy facilities, autonomous power supply centers for industrial enterprises, APG gathering and transportation facilities, auxiliary power supply complexes of fields, and special purpose facilities (test benches for gas turbines and technical training centers).



With each implemented project, ENERGAS increases organizational practice and improves engineering professionalism. Today we have 149 projects in 36 regions of Russia and the CIS countries. Since 2007, 290 process units have been commissioned or are being prepared for launch.

These units are designed for various purposes; they have various versions and modifications. They are combined into the ENERGAS equipment complexes of the following types:
  • Multifunctional gas treatment and gas supply system;
  • System for comprehensive associated gas treatment;
  • Booster compressor station for fuel gas;
  • Compressor station for associated gas transmission;
  • Multipackaged (multi-module) fuel gas treatment unit.
POSTSCRIPT

Thus, the Kaliningrad Region has received energy bases for achieving faster rates of socio-economic development. The region has created conditions for power supply in an isolated mode. The task of energy security in area is solved.



Against this background, the position of the Baltic countries is remarkable, as they announced their exit from the post-Soviet unified energy system BRELL until 2025, which directly threatened the Kaliningrad Region as it turned into an "energy island".

Thus, after the commissioning of new Kaliningrad facilities, in the same Lithuania they were worried that Russia itself could withdraw from BRELL ahead of schedule before 2025, and this is fraught with possible energy shortages and even "blackout" already for the entire Baltic States. They also spoke about the rapid growth of the generating of the Kaliningrad Region allegedly "for blackmail" in order to "bill Lithuania" for staying at BRELL, taking advantage of the fact that it is not ready for synchronization with European networks.

Will Russia remain at BRELL until 2025, while the Baltic States are just preparing to leave the existing energy ring? In response, ITAR-TASS quoted the Deputy Prime Minister of the Russian Government, Dmitry Kozak: "We have the willingness to work, including until 2025, but on different terms".

Photos: russos.livejournal.com, vostokphotos.ru, energas.ru

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