Scaling and corrosion, in combination with high salinity and high temperatures, was one of the main design challenges. In order to avoid silica scaling, a steam pressure of 18 bar was required, which is considered unusually high for a geothermal plant.
The production boreholes, 2.000-3.000 m deep, produce a mixture of steam and brine. The mix is collected and piped to a steam separator. Before entering the turbine, the steam passes through a moisture separator. The turbine has been designed by Fuji for an 18 bar inlet pressure, which is unique. The turbine is of a single cylinder, double flow type. It is provided with special measures to allow cleaning of deposits, with units on line and several other features to increase tolerance against erosion/corrosion.
Once the energy has been harnessed, the steam flows to a shell and tube condenser where it is condensed at -0,90 bar using 4.000 l/s of 8°C seawater, pumped from boreholes located in proximity of the nearby coastline. The condensate, mixed with the brine coming from the steam separator, is piped to the brine injector where it is mixed with the seawater. The mix is then finally discharged via a 2 km water channel into the sea at 60°C.
The monitoring and control system is operated remotely from the Hitaveita Suðurnesja main control room and is composed of a redundant double industrial computer system and a redundant double fiber optic cable connection in order to maximize safety in case of failure in the control and supervisory system.
Verkís services was project management and design supervision, detail design, tender documents and procurement: structural design, mechanical design, piping systems, ventilation, control and monitoring equipment. Supervision of construction work, testing and start-up activities.
The Challenge
Reykjavík Energy owns the Hellisheidi geothermal power plant, a combined heat and power plant located about 20 km from Reykjavík in south-west Iceland. The area is one of Iceland’s most active high enthalpy areas. A new area, at Gráuhnúkar, is being investigated for steam and fluid extraction. The purpose of the plants is to meet increased demand for electricity for industrial and domestic use and for hot water for heating. The 303 MWe geothermal power plant in Hellisheiði, Iceland, was commissioned in 5 stages during the years 2006-2011. The first stage was completed in 2006 with two high pressure geothermal turbines of 45 MWe capacity each. The second stage was completed in 2007 with one low pressure geothermal turbine of 33 MWe capacity. The third stage was completed in 2008 with two additional high pressure geothermal turbines, 45 MWe each.
In 2010 a heating plant for hot water generation was added to the plant, intended for district heating. The heat output of the first stage is 133 MWth and two further 133 MWth stages are to follow later. At the same time the Hellisheiði hot water main was put into service. The main is a 19,5 km long pipeline, 0,9-1,0 m in diameter, that carries hot water to Reykjavík. In 2011 the 5th stage of the plant was finished, which includes two new 45 MWe high pressure geothermal turbines, similar to the former turbines, situated in a new power house in Sleggjubeinsdalur.
The plant utilizes 500 kg/s of 180°C geothermal steam for electrical generation. The hot fluid is extracted from 30 wells, 2.000 – 3.000 m deep, and is led through steam and mist separators before entering the turbines. The high pressure steam gathering system operates at 9 bara pressure. The low pressure steam is generated with flashing of brine water from the steam separators at a pressure of 2 bara. The generating units are of single flow, single flash type with axial exhaust. Cooling is achieved through wet cooling towers of the counter flow type.
The main components of the electrical system for each unit consist of a 50 MVA generator, 50 MVA step-up transformer to 220 kV transmission voltage, an 11/11 kV transformer for connection to the 11 kV station service system and two 11/0,4 kV transformers for station service. The generating units, as well as the 11 kV and 0,4 kV distribution boards, are monitored and controlled by the state of the art control- and protection equipment.
Our Solution
Reykjavík Energy owns the Hellisheidi geothermal power plant, a combined heat and power plant located about 20 km from Reykjavík in south-west Iceland. The area is one of Iceland’s most active high enthalpy areas. A new area, at Gráuhnúkar, is being investigated for steam and fluid extraction. The purpose of the plants is to meet increased demand for electricity for industrial and domestic use and for hot water for heating. The 303 MWe geothermal power plant in Hellisheiði, Iceland, was commissioned in 5 stages during the years 2006-2011. The first stage was completed in 2006 with two high pressure geothermal turbines of 45 MWe capacity each. The second stage was completed in 2007 with one low pressure geothermal turbine of 33 MWe capacity. The third stage was completed in 2008 with two additional high pressure geothermal turbines, 45 MWe each.
In 2010 a heating plant for hot water generation was added to the plant, intended for district heating. The heat output of the first stage is 133 MWth and two further 133 MWth stages are to follow later. At the same time the Hellisheiði hot water main was put into service. The main is a 19,5 km long pipeline, 0,9-1,0 m in diameter, that carries hot water to Reykjavík. In 2011 the 5th stage of the plant was finished, which includes two new 45 MWe high pressure geothermal turbines, similar to the former turbines, situated in a new power house in Sleggjubeinsdalur.
The plant utilizes 500 kg/s of 180°C geothermal steam for electrical generation. The hot fluid is extracted from 30 wells, 2.000 – 3.000 m deep, and is led through steam and mist separators before entering the turbines. The high pressure steam gathering system operates at 9 bara pressure. The low pressure steam is generated with flashing of brine water from the steam separators at a pressure of 2 bara. The generating units are of single flow, single flash type with axial exhaust. Cooling is achieved through wet cooling towers of the counter flow type.
The main components of the electrical system for each unit consist of a 50 MVA generator, 50 MVA step-up transformer to 220 kV transmission voltage, an 11/11 kV transformer for connection to the 11 kV station service system and two 11/0,4 kV transformers for station service. The generating units, as well as the 11 kV and 0,4 kV distribution boards, are monitored and controlled by the state of the art control- and protection equipment.
The Result
Reykjavík Energy owns the Hellisheidi geothermal power plant, a combined heat and power plant located about 20 km from Reykjavík in south-west Iceland. The area is one of Iceland’s most active high enthalpy areas. A new area, at Gráuhnúkar, is being investigated for steam and fluid extraction. The purpose of the plants is to meet increased demand for electricity for industrial and domestic use and for hot water for heating. The 303 MWe geothermal power plant in Hellisheiði, Iceland, was commissioned in 5 stages during the years 2006-2011. The first stage was completed in 2006 with two high pressure geothermal turbines of 45 MWe capacity each. The second stage was completed in 2007 with one low pressure geothermal turbine of 33 MWe capacity. The third stage was completed in 2008 with two additional high pressure geothermal turbines, 45 MWe each.
In 2010 a heating plant for hot water generation was added to the plant, intended for district heating. The heat output of the first stage is 133 MWth and two further 133 MWth stages are to follow later. At the same time the Hellisheiði hot water main was put into service. The main is a 19,5 km long pipeline, 0,9-1,0 m in diameter, that carries hot water to Reykjavík. In 2011 the 5th stage of the plant was finished, which includes two new 45 MWe high pressure geothermal turbines, similar to the former turbines, situated in a new power house in Sleggjubeinsdalur.
The plant utilizes 500 kg/s of 180°C geothermal steam for electrical generation. The hot fluid is extracted from 30 wells, 2.000 – 3.000 m deep, and is led through steam and mist separators before entering the turbines. The high pressure steam gathering system operates at 9 bara pressure. The low pressure steam is generated with flashing of brine water from the steam separators at a pressure of 2 bara. The generating units are of single flow, single flash type with axial exhaust. Cooling is achieved through wet cooling towers of the counter flow type.
The main components of the electrical system for each unit consist of a 50 MVA generator, 50 MVA step-up transformer to 220 kV transmission voltage, an 11/11 kV transformer for connection to the 11 kV station service system and two 11/0,4 kV transformers for station service. The generating units, as well as the 11 kV and 0,4 kV distribution boards, are monitored and controlled by the state of the art control- and protection equipment.
Icelandic
