By Lynne Anderson, Alstom Industrial Turbines, Sweden
Intent on promoting business development, the City of Moscow is constructing new business and high-tech facilities such as the Moscow International Business Centre. At the heart of this new development will be a combined cycle plant providing a reliable supply of heat and power.
Moscow today is a centre of financial and business activity with a dynamically developing infrastructure and information environment, and a highly qualified workforce. The city administration is focusing on creating a business-friendly environment and promoting development. A significant number of projects are under implementation – both construction projects for social facilities and industrial projects including high-technology and conversion.
The creation of the Moscow International Business Centre (MIBC) or ‘Moscow City’ as it is called locally, is a pioneer project within Russia and Eastern Europe. The goal of the project is to combine business, living and leisure in a single area. This gigantic project involves the creation of 2.5 million m2 of office, hotel, retail and leisure facilities, characterized by use of multi-storey building and the concept of multifunctional space. A modern transport structure will be provided for metro stations, mini-metro and highway construction, and state-of-the-art telecommunication systems will be installed. The City will be powered by resource-saving technologies, using independent power and heat supply systems.
MIBC will be located on Krasnopresnenskaya Naberezhnaya, the only site in the centre of Moscow where a business district of such scale is permitted to be developed. The Centre will be built in several phases. Prioritized projects for design and construction in the initial phase 2000-2003 naturally include the establishment of power supply sources with relevant distribution network and supporting technological structures, as well as the development of engineering and transport infrastructure of the central part of the city
Figure 1. Flow chart of the Moscow City combined cycle plant
The development of MIBC ‘Moscow City’ is managed by City JSC (Joint Stock Company), established in 1992, with active support from the Moscow City government. City JSC acts as the developer of the overall project as well as the leaseholder of land as agreed with the Moscow City government.
When City JSC and Mosenergo JSC investigated alternative solutions for energy supply to the MIBC development complex, the main considerations were minimal capital investments and high technical reliability. To meet these criteria, JSC ‘City-Energo’ together with Alstom Power Sweden AB was able to offer two KAX-100-2DH ‘Mini-HES’, a combined heat and power plant based on the GTX100 gas turbine. The first Mini-HES (Heating and Electricity Station) is now being constructed under the terms of the contract for phase one, with the second to follow soon.
Combined cycle plant
The KAX-100 DH Mini-HES is one of three independent sources of heat and power being developed for the Business Centre. The phased development will cover the following work and technological installations:
- Relocation of the existing Mosgortop coal store
- Relocation of administrative departments of the asphalt plant previously located there
- Construction of phase one of the CHP plant (43 MWth) and construction of phase two (up to 116 MWth)
- Gas pipeline (two lines) with a total length of 1 km
- To cover heat shortage, the installation of two 140 MWth peak water heating boilers, produced in Russia
- Communication with the Mosenergo system (power excess rejection)
- Main networks for heat and power supply from the Mini-HES to Moscow City, a total length of 1.4 km.
The first phase of project construction includes two combustion gas turbines (GT) fired with natural gas, two heat recovery steam generators (HRSGs), one district heating condensing steam turbine (ST), one peak water heating boiler and auxiliary systems to form a complete combined cycle power plant for the production of electrical power and hot water to the district heating network. The main components and systems will be designed, manufactured and delivered by an international network of Alstom business units. The peak water heating boilers are being designed and constructed by JSC Drogobuzhkotlomash of Russia.
Figure 2. Alstom’s 43 MW GTX100 gas turbine will form the heart of the new power plant in Moscow
Electrical power is produced in three synchronous generators, two driven by the gas turbines and one by the steam turbine. The electrical power produced is fed to a 110 kV and a 20 kV switchgear. The 110 kV switchgear provides the plant with auxiliary power at start-up. The produced district heating water is fed to MIBC.
Hot exhaust gases from the gas turbines generate steam of two pressures in the HRSGs. These high pressure and low pressure steam flows are produced by the HRSG at superheated conditions and fed to the steam turbine, which is connected to a two-stage district heating condenser system.
A summer cooler will also be installed to cater for operation cases when heating water requirements are low.
The power plant can be controlled and monitored from the central control room, the buildings being provided by the customer. There is a high degree of automation throughout, and it is intended that the power plant should be able to be operated unattended.
Figure 3. Schematic diagram of the new Moscow City power plant, which is scheduled to start operating in simple cycle mode early next year
The high exhaust temperature of 1015à‚°F (546à‚°C) at ISO base load ensures very good efficiency ratings for the combined cycle plant, with the 2×1 combined cycle reaching values of more then 50 per cent efficiency on natural gas. The total coefficient of thermal effectiveness is as high as 85 per cent.
Under its contract, Alstom’s scope of work includes the supply of two GTX100 gas turbines with auxiliaries, two heat recovery steam generators with auxiliaries and a feedwater system, one steam turbine with auxiliaries, three synchronous generators, and district heating condensers and district heating system facilities within the power plant building. In addition, Alstom will supply two typical heat-extraction water heating boilers, the fuel gas supply system, the steam and water system, and the closed cooling water and compressed air systems. The company is also responsible for:
- Plant control system and instrumentation
- Raise-up transformer substation with relay protection
- Electrical equipment, low voltage
- Project management, quality assurance, design and manufacturing
- Transport to site, supervision of erection and commissioning
- Documentation and training.
The GTX100 gas turbine is a modular industrial gas turbine. It is of single shaft design, driving the electric generator through a parallel shaft reduction gear.
The gas turbine is mounted on a steel base frame with an integral oil tank and other auxiliaries. The package is a single natural gas fuel variant and includes the Alstom Power AEV dry low NOx combustion system.
Figure 4. The foundations are cast for the first phase of the combined cycle plant in the heart of Moscow
A sound enclosure is located over the gas turbine and gearbox to ensure 85 dBA external noise limits at 1 m. The enclosure is fitted with ventilation units, gas detection and fire suppression systems, and access ways for personnel during maintenance.
Combustion air is cleaned through a three-stage static type of intake filter. An anti-icing system and silencer are located at the air intake duct.
The steam turbine is of ST4 type, an MP16 consisting of one multi-stage district heating condensing turbine. The steam turbine and its electric generator are mounted directly on the turbine’s concrete foundation. The steam turbine lube-oil reservoir is placed beside the steam turbine gearbox and the AC generator. An accessible sound enclosure is located over the gear to ensure required noise levels are adhered to.
The water/steam circuit consists of a heat recovery steam generator (HRSG) which generates steam by extracting heat from the exhaust gas flow of the gas turbine.
The HRSG is designed as a dual-pressure, natural circulation boiler comprising:
- Stack with silencer
- Low pressure (LP) economizer
- LP evaporator with steam drum
- LP superheater
- High pressure (HP) economizer
- HP evaporator with steam drum
- HP superheater.
The steam which is generated is expanded in the steam turbine and the mechanical energy thus provided is used to turn the shaft of the generator.
The steam is condensed in the district heating condensers. The condensate is collected in the hotwell and then pumped to the feedwater tank via a heat exchanger, transferring heat from the feedwater to the condensate. Demineralized water is mixed with the condensate to cater for loss of condensate.
In the direct contact feedwater/deaerator the condensate is preheated and deaerated by hot LP feedwater extracted downstream of the LP economizer. The feedwater storage tank serves to compensate for variations in the water supply of the water/steam cycle and to accumulate volume changes in the cycle.
From the feedwater tank the feedwater is pumped to the HRSG, the feedwater control valves and the speed controlled HP feed pumps governing the flow. The HP and LP feedwater pumps also serve all attemperators. One pump of each pressure is in operation up to full load, one pump serving as standby. Should an operating pump fail, the standby is automatically switched on.
To increase the flexibility of operation and start-up of the plant, LP and HP pressure-reducing stations and dry-air condensers are provided. Both bypasses are designed for the full HRSG capacity. The ST bypasses serve to let the HP and LP steam bypass the ST down to the condenser, and enter operation in the event of ST start-up and shutdown or ST load rejection or trip.
The power from the synchronous generators is transferred via three two-winding transformers, one for the steam turbine and two for the gas turbines, to a 110 kV switchgear and then via two three-winding transformers to a 20 kV and 10.5 kV switchgear.
Auxiliary power is transferred from the 110 kV via the 11 kV gas turbine generator switchgears and via auxiliary transformers to the 10 kV switchgears. When a generator is in operation it provides the auxiliary power. When it is not, the auxiliary power is taken from the grid.
Low voltage (400 V and 690 V) is supplied via two three-winding auxiliary transformers 10/0.69/0.4 kV. Low voltage switchgears distribute electrical power to motors and heaters as applicable at the various operating modes of the plant.
Uninterruptible Power Supplies (UPS) ensure a safe power supply to the control system and DC supplies are used for GT and ST emergency power to ensure safe cooling, electrical protections and safety systems.
The layout concept represents an optimal utilization for the site conditions. The main advantages of this concept are:
- Short connections between all major plant components (piping and cables) resulting in reduced energy losses.
- Short distances providing for easy operation and maintenance.
- Adequate separation between the power train and the balance of plant components to facilitate maintenance.
The proposed layout offers good access to all components in the power station. Lifting beams are installed in the enclosures serving main equipment for easy maintenance and overhaul. A hoist is installed to transport components up and down between base level and the service levels of the HRSGs.
All electrical and control equipment, apart from that associated with the gas turbines and the Advant Operator Stations are housed in the customer-provided electrical and control building. The Operator Stations will be located in the main plant control room. The power plant can also be operated from the local GT control room.
The technical and economic feasibility study for the first phase of the new combined cycle power plant, covering the power plant with gas turbine equipment, gas pipelines and main underground networks for heat and power supply, was approved 6th April, 2001. Preparation work on the construction plot release began immediately, design work being completed by May 2001, when construction work took over. In parallel, the development was initiated for the main conduit for the heating system and 20 kV cable from the power plant up to MIBC Moscow City.
Since then, the Moscow City project has moved forward swiftly. At the time of writing, the foundations for the first two-turbine unit have been cast – 400 m3 concrete in each – a major milestone in the customer’s undertaking. In Sweden, the first GTX100 combustion turbine is being prepared for delivery in August, with the second to follow in September, seven weeks later. The steam turbine will be delivered in February 2003.
The 232 MW plant will start as a simple cycle to meet urgent power needs, and then switch to combined cycle and district heating in accordance with the long-term plans. The first unit is scheduled to be in operation in simple cycle in January 2003 and the second is scheduled for July 2003, in combined cycle. The complete phase 1 of the district heating unit should be operational in time for the 2003-2004 winter heating season.