Heat recovery steam generators
HRSGs for Russia & CIS1 October 2009
CMI of Belgium has supplied both vertical and horizontal gas flow HRSGs to Russia and the CIS countries. What factors influence the choice of configuration?
While Russia and the countries of the former Soviet Union have only relatively recently embraced large combined cycle plants, there are now a number of natural gas fired CCGTs at various stages of completion in the CIS region, although current financial problems make the future outlook uncertain.
CMI of Belgium has provided the heat recovery steam generators for several ongoing projects in Russia, Azerbaijan and Kazakhstan. Both vertical and horizontal gas flow units have been supplied, and the projects provide a good illustration of the kind of factors that influence the choice of orientation.
In Russia, CMI has supplied, or is supplying, HRSGs to five combined cycle plants, Saint Petersburg, Shatura, Nevinnomyssk, Yayva, and Surgut – a total of nine boilers to date.
Construction of the Saint Petersburg combined cycle plant, with an installed capacity of 900 MW, goes back to the late 90s. CMI supplied four vertical HRSGs.
The 400 MW Shatura facility is estimated to be about 98% complete, with full commercial operation now expected in spring 2010. The CCGT is owned by OGK-4, in which E.On has a 78.3% share. It is being constructed on the site of an existing power plant, about 150 km east of Moscow. The triple-pressure reheat HRSG, which is designed and fabricated in accordance with Asme and Gost certification. The HRSG is of the horizontal type and will be downstream of a GE 9FA gas turbine. The HRSG is designed for cycling operation. A contract was awarded to CMI in June 2007 and its scope includes stack, structural steel and casing, modules, steam drums, large piping, inlet duct walkways & platforms, stack damper, and valves.
The exhaust gas temperature at the inlet to the HRSG is 1096°F, while the gas temperature at the HRSG outlet is 276°F. Steam conditions are: HP, 1033 °F, 1529 psig; IP, 572°F, 367 psig; LP, 561 °F, 73 psig; reheat, 1033 °F, 338 psig.
CMI is providing two further horizontal HRSGs, identical to that at Shatura, to another OGK-4 project, the Surgut combined cycle plant in Siberia, which basically consists of two Shatura type units, with GE 9FA gas turbines. The similarity of the projects brings advantages, says Dan Levstek of CMI: “we can satisfy the client without taking on extra resources, order our our materials in advance and therefore obtain better prices.”
Surgut is expected to achieve commercial operation in summer of 2010.
CMI is also the HRSG supplier to a third OGK-4 CCGT, the 450 MW Yayva combined cycle project, at the foot of the Urals, in southern Siberia. For Yayva the HRSG will be of the vertical orientation, downstream of a Siemens SGT5-4000F (formerly V94.3A) gas turbine to be supplied by Power Machines. The Yayva HRSG design is close to that of the boilers supplied by CMI to Talkha and Kureimat, in Egypt.
The Jayva plant is in a region where winter temperatures can drop to as low as -48°C. Indeed, the extreme weather constitutes one of the greatest challenges of the project for the HRSG supplier. The rivers are permanently frozen except for two months of the year, the only window of opportunity for transporting HRSG modules and drums, which are too large to be moved by road. The parts must be supplied on time, within this window, otherwise it becomes necessary to wait another 10 months!
Another consequence of these extreme climactic conditions is that it is impossible to use a crane for assembly: it is much too cold to work outside and installation has to be done within a closed building. The cold has thus dictated the use of vertical HRSG technology at Yayva, allowing main components to be lifted into position within a closed building. Use of a horizontal-flow type would have required a crane to be used to lift the tube bundles.
In the case of vertical-gas-path HRSGs, the modules themselves are in fact horizontal and lifted into position inside the casing by lifting jacks. They are horizontal in the workshops and remain horizontal on the site, so there is no need for a crane to lift them. The jacks lift the modules one by one inside the boiler itself.
In the case of HRSGs with a horizontal gas path, there is a need to use at least one crane, but most of the time two (600 t and 150 t) to lift the bundles.
Extreme weather aside, the choice between horizontal or vertical HRSGs mostly depends on the space available at the site. To erect a vertical HRSG, less space is needed because there is no need to install large cranes.
In the Yayva case, the HRSG order was placed by Enka, the Turkish civil engineering company and power plant EPC contractor and owner, which, since the beginning of the 1990s, has been very active in the energy sectors of the countries of the former USSR.
This is the third time CMI and Enka have worked together. In fact Enka is the company with which CMI signed its first major HRSG contract, 20 years ago (for eight boilers, with a total installed capacity of 1200 MW, for Trakya A&B in Turkey). The second order given to CMI by Enka was awarded a few years later, for Adapazari and Izmir (also Turkey) – a total of ten boilers, the last entering service in 2002.
The Yayva plant, with a project start date of March 2009, first deliveries to site in January 2010 and start of erection March 2010, is to be commissioned in July 2012, but the schedule is under review. Engineering is currently about 50% complete.
A vertical HRSG housed in a building will also be employed at OGK-5’s Nevinnomyssk combined cycle project, which is located 300 km north east of Sochi, on the Black Sea – again at an existing power plant site, becoming unit No 14 there. OGK-5, in which ENEL has a controlling 55.78% stake, placed the EPC contract for Nevinnomyssk last year with a consortium of ENEL Produzione and nuclear plant builder Atomstroyexport. The gas and steam turbines will be supplied by Power Machines.
Projects in Azerbaijan and Kazakhstan
Over the border, in Azerbaijan, CMI has supplied a total of three HRSGs. Back in 2000 it won an order to supply a vertical unit to the 400 MW Severnaya combined cycle plant, which entered commercial operation in 2002. This triple pressure unit is downstream of a Mitsubishi M701F gas turbine.
More recently, in August 2005, the company won a contract (from Siemens) to supply two horizontal HRSGs to the 400 MW Sumgait combined cycle plant in Azerbaijan, close to Baku. This consists of two Siemens SGT5-2000E (formerly V94.2) gas turbines, the HRSGs and a single steam turbine. The HRSGs, with two pressure levels and no bypass stacks, are designed for baseload and cycling operation.
An interesting feature of this project was that due to local transport limitations, the HRSG modules had to be manufactured at site. The plant went into operation in September 2007.
At the smaller end of the size spectrum, CMI has also supplied a horizontal HRSG (single pressure) to the 25 MW Uralsk facility in Kazakhstan, operating downstream of an Hitachi H25 gas turbine.