The Tamazunchale I combined-cycle plant is now producing 1,135MW of electricity for the Mexican grid. The plant, located in the municipality of Tamazunchale in San Luis Potosi State, began testing in February 2007 and came on line in June. It burns
natural gas and operates at 56% combined-cycle efficiency.
GE Energy supplied four Frame 7FA gas turbines, two steam turbines, and additional equipment and services. Iberdrola Energía Tamazunchale SA de CV, an affiliate of Iberdrola Mexico, owns and operates the plant. Iberinco Mexico of Mexico
City was the engineering, procurement and construction contractor for the project.
GAS TURBINES AND ASSOCIATED EQUIPMENT
Besides the four 165MW Frame 7FA gas turbines, the contract included two GE D11 reheat, 60Hz steam turbines, six hydrogen-cooled generators, four heat recovery steam generators, a plant industrial control system and a plant central emissions
monitoring system. GE also provided site support and training services.
GE and Iberdola Energía signed a 25-year contractual service agreement that covers planned and unplanned outages and includes performance guarantees. The gas turbines were manufactured at GE’s facility in Greenville, SC, and the steam turbines and generators will be manufactured in Schenectady, NY.
The equipment was delivered to the project site from October 2005 to January 2006.
The Frame 7FA gas turbines are members of GE’s F technology family, which has compiled more than 10 million fired hours in power plants worldwide. GE technology provides approximately half of the private power capacity in Mexico, including nearly
4,000MW of Iberdrola’s installed capacity in the country.
Bids were requested for the 1,016MW Tamazunchale II CCGT plant in 2005, and a third, 506MW Tamazunchale III is planned for 2010.
Dry low NOx (DLN) combustors for GE Frame 7FAs are now operating at 9ppm NOx, with even lower levels likely in the next few years. The cost of add-on emission controls to achieve a NOx level below 9ppm becomes excessive and the overall environmental
impacts may actually be worsened with this design.
As F-technology gas turbines became available in the late 1980s, studies were conducted to establish what type of DLN combustor would be needed for these new higher firing temperature machines. The conclusion was that air usage in the combustor other
than for mixing with fuel (e.g. for cooling) would have to be strictly limited.
A team of engineers from GE Power Systems, GE Corporate Research and Development and GE Aircraft Engines proposed a design that repackaged DLN-1 premixing technology but
eliminated the venturi and centerbody assemblies that require cooling air. The resulting DLN-2 combustor is the standard system for the company’s 6FA, 7FA and 9FA machines. 14 combustors are installed in the 7FA, 18 in the 9FA, and six in the 6FA.
TAMAZUNCHALE I CONTRACT
The highly prized contract for Tamazunchale I was awarded to Iberdrola in July 2004, and when it came on line brought Iberdrola’s operational capacity to just under 5,000MW. The plant had been highly contested by the bidders because, for the first time, CFE (Comisión National de Electricidad) guaranteed the supply of natural gas and its
Iberdrola guaranteed to sell all the energy produced at Tamazunchale I to the CFE for 25 years. The contract currency is US dollars, as is the case for the company’s other projects in Mexico.
The gas will come from the planned Altamira LNG regasification plant. CFE put out another IPP project to bid in 2004: the 456MW combined-cycle natural gas-fired plant, Agua Prieta II.
LNG PIPELINE TO TAMAZUNCHALE
State oil and gas company Pemex also invited bids for the construction of a 180km pipeline from the country’s first LNG receiving terminal at Altamira on the Gulf of Mexico to the Tamazunchale plant. The pipeline began carrying gas in October 2006, and is Mexico’s second largest owned by the private sector; the largest is the 690km Gaz de France-InterGen Mayakan line from Tabasco to Yucatan in the south-east.
The capacity of the Altamira-Tamazunchale pipeline is 400 million ft³/d. The announcement of the tender ended speculation that the project would be assigned to Pemex itself.