Fast gearbox repair at Geothermal power plant, Italy

Challenge

Italy is where geothermal energy was used for the first time for industrial purposes, and the country remains one of the leading producers of geothermal electricity. The first geothermal power plant was built in 1904 located at Lardarello, Italy. Today, it's the home of our customer Enel. Enel Green Power currently manages 31 geothermal power plants in Tuscany, with more than 8,700 district heating users, geothermal heat for 25 hectares of greenhouses, and power generation of more than 5 billion kWh per year, equal to the average consumption of 2 mln Italian households.

Stork Gears & Services was invited by Enel to investigate the gearbox (MAAG type G-247/3) after a sudden increase of vibration levels. The gearbox is part of a dry steam power installation, any gearbox downtime results in lost revenue - electricity - to the end users. A fast and reliable response was required.
End of August 2008 a catastrophic breakdown in one of the Geothermal Power Station occur, and damaged one of the 60mW installations. During a meeting on side, we adviced the customer to send the damaged gearbox to our workshop for extended inspection. After full inspection of the gearbox a detailed damage report is handover to Enel. The order for repair was given by Enel and the expected delivery time was 12 weeks. In week 50 the repaired gearbox was send back to the power plant for installation on side.

Solution

• Reverse construction of a tooth coupling

• Manufacture of the LP and HP output couplings, probes and missing measure parts

• Reconstruction broken cover, bolts, studs, nuts, secure plates and assembling parts for the final functionality of the gearbox

• Manufacture of one gear set according to drawing

• Refurbishment and reverse engineering of bearings

• Restoring teeth profile by grinding one gear set according drawing

• Dismantling, inspection and engineering, assembling and testing the complete gearboxed

• Dismantling barring device, re-construction of the lower casing by reverse engineering

• Repair damaged gears and manufacture one complete set internals for the second barring device, bearings included

• Assembling repaired gears and a new set of gears into a new casing supply

• Test-run both bearing device after assembling
 
Converting the earth´s heat to electricity: Geo (Earth) thermal (heat) energy is an enormous, underused heat and power resource that is clean, reliable and homegrown. In the field of geothermal energy, the term "energy conversion" refers to the power-plant technology that converts the hot geothermal fluids into electric power. 

Benefits

Direct steam plants are used at sites where the geothermal resource consists of high-quality steam. The steam is routed directly through a steam turbine which drives a generator that produces electricity. The steam eliminates the need to burn fossil fuels to run the turbine, one of the great environmental advantages over conventional power generation.

A geothermal power plant is generally built where geothermal reservoirs are located within 60 to 3000 meters of the surface. The steam inside these reservoirs is then piped to the surface through the wells. The steam pipes -which are at most some kilometer long, see the picture – convey the steam to the plant. The energy present in the steam, which is subsequently expanded through a turbine which is coupled to an electrical generator, is firstly converted into mechanical energy which, in turn, is converted into electric energy. The exhausted steam from the turbine is transferred to the condenser, where it is converted into high temperature water, which flows through the cooling tower, where it is cooled down and injected into the subsoil. source: Office of Energy Efficiency & Renewable Energy.

Location: Italy 

Market segment: Power plant