Tim Probert, Deputy Editor
Cairo is growing at a rate of knots. Africa’s biggest city is expanding like an ever-increasing circle; from the 6th of October City and 10th of Ramadan City developments to New Cairo, the Egyptian capital is one of the fastest-growing metropolises in the world.
Of course, such a breakneck pace requires a great deal of electricity. The annual average rate of growth of electricity demand is expected to range from 6.5-7.5 per cent during this decade and the Ministry of Electricity and Energy estimates that at least an additional 13 GW of new generating capacity will be required.
Kureimat II CCPP featuring two Siemens SPG5-4000F gas turbines and two vertical, natural circulation HRSGs from CMI
In 2002, the ministry drew up a plan to put an additional 4500 MW on Egypt’s national grid, to be implemented by the Power Generation Engineering and Services Company (PGESCo). PGESCo was formed back in 1993, as a venture between Bechtel Corporation and Egypt’s Ministry of Electricity and Energy, each of which owns 40 per cent of the company.
The Arab African International Bank originally owned the remaining 20 per cent, but it has since sold its interest to the Commercial International Bank. Under this arrangement, no partner has a majority share, and the bank can mediate any differences.
Under the auspices of the Egypt Electricity Holding Company and its subsidiary the Upper Egypt Electricity Production Company, PGESCo set about expanding the existing capacity at the small, nondescript town of El Kureimat, 90 km south of the capital on the eastern side of the Nile, reached by a speedy new motorway built by the military.
Other PGESCo projects in Egypt include Sidi Krir I-IV (combined 1300 MW thermal), Nubaria I and II 1500 MW combined-cycle gas turbine (CCGT) and Cairo North I and II (combined 1500 MW CCGT) and the 750 MW Talka CCGT project.
El Kureimat is the last of the 2002-planned power plants that will make up the additional 4500 MW capacity. It is already home to an existing 1300 MW gas and heavy fuel oil (mezut) thermal power plant. El Kureimat II, a 750 MW CCGT unit, was commissioned in June.
When PEI visited the plant in October, PGESCo was undertaking the reliability run at El Kureimat II, and the new unit was then scheduled to be given a final performance test, due to have been completed by 25 October. El Kureimat III, currently undergoing construction and expected to be commissioned in August 2010, will be a duplicate of 750 MW CCGT unit.
Hub of Egypt’s power grid
When complete, the El Kureimat site will provide 3000 MW to the Egyptian grid. Armin Kelly, of Bechtel Corporation and site manager of El Kureimat for PGESCo, says El Kureimat will eventually become Egypt’s largest centre of power and a key component of the North African nation’s ambitions to become an exporter of electricity to the burgeoning regional electricity network and perhaps further afield.
He said: “The whole goal of the PGESCo expansion was to enhance the Seven Countries Interconnection Project (EIJLLST Egypt, Iraq, Jordan, Lebanon, Libya, Syria and Turkey) and finally the long-term goal of connecting with the European grid. There was also talk of building a backbone running south to the hydroelectric areas of Africa, but there are many issues.
Kureimat III currently under construction based on a duplicate design from Kureimat II
“PGESCo wants to build enough capacity to be able to export, but unfortunately the growth in Egypt in phenomenal around eight per cent a year and they are barely keeping up with it in terms of power. The other thing here is that the environment is tough on power plants, and the ageing plants have done little to abate this problem.
“The high temperatures affect efficiency we don’t put in turbine inlet cooling here. The population is growing, there is a great deal of economic growth and the whole place is booming. There is a lot of construction going on and they are expanding their trade ports.”
With nine power plant projects active in the country and expansion of the cement factories, ports and the city ongoing, there is quite a strain on engineering resources, not least the engineers themselves. Kelly says that Kureimat II and III are both 29-month projects, typically six months longer than elsewhere, due to the complicated financing and phasing processes.
In total there are 1350 employees on the El Kureimat site, working on units II and III, representing two dozen nationalities.
The civil engineering contractor is a quasi-state consortium of Arab companies in partnership with Worley Parsons. The expatriot component of El Kureimat power plant projects is actually very limited, with most work being done by Egyptian contractors.
Kureimat II vital statistics
Siemens has provided two heavy-frame SGT5-4000F V94.3A gas turbines (which are also capable of firing No. 2 fuel oil) with a 250 MW nominal rating, each feeding exhaust gases to its respective heat recovery steam generator (HRSG), made by Belgian manufacturer CMI.
Steam from the two HRSGs is fed to one 250 MW (nominal), indoor single reheat condensing steam turbine generator (STG), made by Hitachi. The facility’s net output is 750 MW (nominal, ISO).
Prefabricated heat exchanger modules arriving from South Korea on a hydraulic traine
This output will be achieved by burning natural gas in the combustion turbines with no supplementary firing in the HRSGs. NOx emissions will be controlled by dry low-NOx combustors. An inlet air filtration system will be included to supply suitable filtered combustion air to the gas turbines.
The steam exhausted from the steam turbine will be fed into a once-through cooling, single-pass, divided water-box condenser. Power is generated at manufacturer’s standard voltage in the CTGs and the STG, stepped-up through main transformers and fed to the utility grid via the extension of the existing a 220 KV, gas-insulated switchgear (GIS) switchyard. Water for power plant cooling is sourced from the Nile.
CMI Boiler Technology
One interesting aspect of the new Kureimat unit is the HRSG installed by CMI, which has a vertical gas flow arrangement. The open bidding process for the El Kureimat II project saw CMI, since they are boiler experts, elect to form a consortium partnership with Czech firm Skoda Praha on the boiler and the balance-of-plant, that is parts for the pumps and the piping connecting the boiler to the steam turbine.
In February 2006 CMI and Skoda were awarded the contract for the engineering and supply of the two HRSGs and their auxiliaries, including the erection and commissioning. Under the terms of the contract, the boiler pressure parts were fabricated by CMI’s licensee in South Korea.
Feedwater tank common for 2HRSG
The vertical gas flow, natural circulation design of the HRSGs is an evolution from forced circulation resulting from on-site feedback since the early 1990s.
Whereas forced circulation HRSGs require circulation pumps because the drum height is relatively low compared with its evaporator, CMI’s vertical, natural circulation HRSG’s drum is installed high above the evaporator to promote natural circulation, which means no need for pumps, even for boiler start-ups.
The vertical design allows for a more compact installation. CMI’s vertical HRSG installation at Kureimat II uses 12 prefabricated, pre-tested modules, as opposed to horizontal-flow HRSGs with exchanger modules welded together in a long arrangement,. The boiler’s 12 exchanger modules are laid out in a four by three configuration.
Each module weighs 150-200 tonnes. All the modules are attached to the oddbeams (supporting steel frame). The HRSGs feature three pressure and reheat levels to the steam turbine. The gas bypass is between the gas turbine and HRSG.
CMI is a pioneer of vertical HRSG ‘cold casing’, where instead of insulating the casing from the outside, the panels are insulated internally. Originally, CMI vertical HRSG’s design for ducting (inlet, casing, outlet duct and stack) was based on a ‘hot casing’ concept, whereby duct material grade is defined according to the flue gas temperature.
However, when the temperature of the flue gas is above 600 ºC, as is the gas with the Siemens SPG5-4000F used at El Kureimat, and the cross section of the HRSG inlet is more than 9×9 m, it becomes difficult to combine panel strength with avoiding thermal stress.
Therefore, for its vertical design, CMI turns by steps to cold casing based on full internal insulation, applying the same ducting concept as its horizontal HRSG design.
With cold casing metal dilatation there is no dilatation. Cold casing saves money in the design of the HRSG. The cold casing panels are prefabricated and then slotted together on-site. The temperature of the gas flow is some 500 ºC, but the author can testify that the panels are merely warm to touch (around 30-40 ºC).
Phase one of HRSG erection is the erection of the priority A steel structure, the first parts needed to support the modules. Phase two involves lifting the modules, which is no simple task. CMI employs hoisting specialist Hebetec of Switzerland, which uses a hydraulic jacking system instead of large cranes. CMI can lift four boiler modules per day for El Kureimat II, or 12 a week in total much faster than using the traditional method of using cranes.
The next step was to erect the bottom part of the outlet duct and then the platform with the 100-tonne high-pressure, intermediate-pressure and low-pressure drums. With all boiler modules and drums now in place, the connection of all the necessary piping could commence. Finally the erection of penthouse, which supports the stack, could be completed. In all, the boiler housing stands 45 m tall, and the stack is some 80 m tall.
El Kureimat III’s HRSG set-up will be virtually identical, with the exception of a slight modification to the inlet duct in order to connect to a GE gas turbine, which is being used instead of the Siemens gas turbine in El Kureimat II.
Keeping emissions in check
Located in a valley with little wind and clogged with traffic, Cairo has a pollution problem. The government is trying to address that by ensuring its new power stations adhere to international emission regulation standards. El Kureimat II and III are no different.
Kelly said: “We do pre-construction monitoring and post-construction monitoring. During the performance testing we have to verify that we have low NOx emissions.
“We have the same standards of emissions control as if I was building a power plant in the US or Europe; because of our association with lenders like the World Bank, we have very strict emissions monitoring and our levels are to international standard.”
A sign of things to come: a solar/CCGT hybrid power plant under construction at El Kureimat
For unit II, PGESCo has a requirement for an additional fuel source other than gas, namely diesel. This will be commissioned around February 2009. Unit II is scheduled to be commissioned in August 2009. The natural gas for the El Kureimat II, in fact LNG, is supplied by the state natural gas company Egyptian National Gas (EGAS). The electricity is sold to the Electrical Energy Holding Company (EEHC), which is semi-privatized.
EEHC is responsible for a number of regional electricity companies, such as the Middle Delta Power, Cairo Power Company, West Delta Power Company and the Upper Egyptian Electric Power Company, to which El Kureimat supplies its output.
These companies are said to be profit centres that are run in a similar fashion to privatized utilities.
Solar/CCGT hybrid project
Also under construction at El Kureimat, although at present little more than a patch of desert, is an integrated solar island CCGT plant. This intriguing project, led by Iberdrola under the auspices of Egypt’s New and Renewable Energy Authority, will use solar thermal heat collectors to heat water and provide steam for the turbine.
The 150 MW solar/thermal hybrid plant, which is expected to be completed in June 2010, will consist of two 40 MW gas turbines, one 70 MW steam turbine and a 20 MW solar unit.
The solar island consists of a parabolic trough solar field capable of generating about 73 MW (thermal) of solar heat at a temperature of 393 ºC, the related instrumentation and control and control room, and the heat transfer fluid (HTF) system up to the HTF inlet and outlet flanges off the solar heat exchanger(s).
When the unit’s own consumption of 6.3 MW is deducted, the net overall plant capacity becomes 143.4 MW. The total net energy produced by the plant is expected to be 852 GWh per year, which includes the solar contribution of 33.4 GWh per year. This corresponds to a solar share of four per cent of the total annual energy produced by the plant operating at a full load.
Financed by the World Bank, the solar portion of the power plant will costs $111 million out of the total project cost of $327.57 million. With this huge expansion of power and Cairo soon to be home to one of the worlds’ most innovative power projects, these are exciting times indeed for PGESCo’s jewel of the Nile.