Globaltechexport Ltd. designs a unique Gas Pressure Reduction Unit for the second phase of the Yakutsk GRES-2 construction project

As part of the implementation of the second phase of the Yakutsk GRES-2 construction project, Globaltechexport Ltd. developed a conceptual design of a unique Gas Pressure Reduction Unit (PRU) to be incorporated into the gas supply system for Teploelectroproject Design Institute JSC, including preparation of a complete set of design documentation for expert review by Glavgosexpertiza.

The main challenge to be solved by Globaltechexport Ltd. was to locate the PRU in a limited space within the existing station. The area allocated for the PRU was no more than 700 m². In addition, the Customer’s specification required two technologically independent pressure reduction lines (1 operating + 1 standby). The task was also complicated by the fact that the only land plot available for the construction of the PRU building lied between the site fence and operating buildings of the station, including associated utilities. It was also impossible to expand the area of the facility due to the dense urban development starting just outside the station area.

Specialists at Globaltechexport Ltd. found that the conventional linear PRU equipment arrangement would need a building being at least 37 meters long and 24 meters wide. At the same time, pursuant to SP 62.13330.2011 (Clause 6.2.3), the PRU shall be single-storey, which made the design inputs even more tight.

Besides, according to SP 4.13130.2013 (Clause 8.2.1), buildings of functional fire hazard class F5 that are more than 18 m long shall have access ways for mobile firefighting units on two sides resulting in the need to design an additional bypass road. Therefore, pursuant to the applicable regulations for conventional arrangements typical for this building type, the area for PRU accommodation shall be 3,000 m² or more. Given the circumstances, it was physically impossible to use a conventional arrangement within the allocated area either in the building or in a modular configuration.

These limitations could have a detrimental effect both on the ability to meet the target construction dates set for the second phase of the Yakutsk GRES-2 construction project and on the construction budget, considering that takeover of the existing urban development area to increase the facility area or transfer of the PRU beyond the territory of Yakutsk were associated with a substantial growth of costs and considerable delays up to a serious risk of disruption of the second phase of the Yakutsk GRES-2 construction project deadlines.

With a wealth of experience in gas equipment design, our team was excited to take on the challenge and not only developed the concept of multilevel PRU equipment arrangement in a single-storey building, which is second to none in Russia, but also prepared the design documentation for submission to Glavgosexpertiza in the shortest possible time (less than 4 months). As a result, the building being only 24 meters long and 12 meters wide turned out to be sufficient to place the equipment within the allocated area.

This design concept is unique as it features a vertical configuration, i.e. multilevel arrangement of process PRU equipment in a single-storey building. This innovative approach was taken to comply with stringent requirements of applicable regulations — according to SP 56.13330.2011 (Clause 4.11), the areas of platforms, racks, and mezzanines shall be a maximum of 40% of the building storey floor area.

Only grating is used on each level where the equipment is located. The piping and equipment layout on each level has been designed to provide any necessary passages and comfortable servicing. To minimize the total area of levels relative to the first storey floor area, the design provides a free space along the entire building (without mezzanines). This space is used for a staircase providing access to various levels and lifting mechanisms to enable equipment disassembly and repairs.

Thus, the overall design openness and “transparency” perform another essential function — providing easy fire-extinguishing agent delivery to any level.

Also, according to SP 4.13130.2013, the PRU building is equipped with a fire escape staircase of Type 3 with access to the roof and each level where process equipment is located to comply with the escape route requirements set by Federal Law No. 123-FZ dd. 22.07.2008 (Article 89). Installation of explosion-proof air-supply units eliminated the need to divide the building into compartments separated by fire walls, which could significantly affect the overall building dimensions.

To implement this approach, design engineers at Globaltechexport Ltd. have also focused on the development of the detailed design documentation for process piping and metal structures of the building, considering the simultaneous installation of equipment and modules with full operational readiness and erection of the building — otherwise space limitations would prevent pipeline and large-size equipment installation.

The building structures have been designed to withstand all process duties with an account of severe climatic and seismic loads in the area of construction.

As part of the set task, our specialists also selected all the necessary equipment providing the highest possible degree of localization, close to 100 percent — according to the Decree of the Government of the Russian Federation No. 719, prepared a full set of design documentation, including process and automation, having overcome all challenges associated with the design of complex configuration buildings in a permafrost seismic danger region, process design, unique equipment arrangement, metal structure and foundation load analysis, automated process control system, power supply, production and installation planning, etc.

The task’s success was based on about a year of meticulous work by our team, studying various layout design options, performing necessary structural analysis, obtaining approvals from the General Designer and the end Customer, including the development of a detailed 3D model.

The vertical arrangement enabled not only the placement of the PRU building within the allocated area but also the installation of a switching valve block on two independent gas supply lines next to the PRU building. This solution made the operation of each PRU line not dependent on the gas source and considerably reduced the gas pipeline routes along the pipe racks, as well as simplified their structural elements.

The creative approach, flexibility, and willingness to innovate demonstrated by HydroOGK Management Company JSC as the end Customer are also worthy of special notice, as the implementation of this first-of-a-kind project enabling considerable budget savings without its participation and support would be impossible.

In August 2024, the set of technical documentation for the unique Gas Pressure Reduction Unit, developed by Globaltechexport Ltd. for Teploelectroproject Design Institute JSC as a key element of the gas supply system on the second phase of the Yakutsk GRES-2 construction project, successfully passed the expert review by Glavgosexpertiza.

Main PRU specifications:

• Compressed medium — natural gas;
• Inlet gas pressure — 1.66...1.9 MPa (g);
• Outlet gas pressure — 0.2...0.3 MPa (g);
• Inlet gas temperature — -34...+50 °С;
• Outlet gas temperature — -10...+60 °С;
• Capacity — 108,000 Nm³/h.