The 200-megawatt Besat Thermal Power Plant in south Tehran is dilapidated after 50 plus years in service. It is close to decommissioning and will be replaced with a modern combined-cycled power plant, director of the project at the Thermal Power Plants Holding Company said.
“We will replace the old power plant that has 20% efficiency with a 330 MW power station with 58% efficiency,” Alireza Nasrollahi was quoted as saying by ILNA.
“The plant consumes 100,000 cubic meters of gas to produce 200 MW of power. The new facility will use 70,000 cubic meters and generate 330 MW,” he added.
Thermal power stations account for 80% of total power generation in Iran and enhancing infrastructure at regular intervals is crucial.
Iran has an installed capacity of 84,500 MW and thermal units account for over 66,000 MW of the total production.
“The project to construct the new power station has two phases: the first is a gas unit with 220 MW capacity and will take two years,” Nasrollahi said, without going into details.
Construction of the steam unit will start later and be ready in two years, the official said.
Besat Power Plant comprises three gas units. “We will not phase out all three units in one go. As soon as the gas unit starts operation, the first (old) gas unit will be decommissioned. The other two gas units will be phased out when the steam unit comes online.”
F-Class Turbines
The modern plant that will replace the ageing facility will use locally made F-class gas turbines designed and developed by Mapna Group.
The turbine consumes less gas and is eco-friendlier and will increase electricity generation via a simple-cycle and combined-cycle power plant by 40% to 59%.
A combined-cycle power plant uses both gas and steam turbines to produce up to 50% more electricity from the same fuel than a traditional simple cycle plant. The waste heat from the gas turbine is sent to a nearby steam turbine to generate electricity.
Mapna Group, a conglomerate of Iranian companies, is involved in the development and execution of thermal and renewable power and plays a key role in upgrading the key power industry.
German engineering giant Siemens signed an agreement with Mapna in 2017 to help modernize the ageing energy infrastructure.
As part of the agreement, Mapna acquired the know-how to manufacture Siemens F-class gas turbines. Now local engineers manufacture the turbines.
The Energy Ministry is gradually phasing out inefficient power plants, improving and expanding electricity infrastructure and acquiring modern technology. However, financial constraints have slowed the process.
Effective steps have been taken to convert conventional plants into combined-cycle units to improve efficiency and reduce pollution and costs.
“Construction of the 330-MW power plant is estimated to cost about $240 million,” Nasrollahi was quoted as saying
Water Consumption
The 52-year old Besat station consumes 18 million liters of water per day to produce 1.2 billion kilowatts a year that is 0.4% of the total annual national electricity output.
The estimated useful life of an electricity plant is 20 years. In addition to being outdated, the problem with Besat is that it has a wet cooling tower preferred where water is plentiful, like the coastal regions.
In wet cooling towers, heat transfer is measured by decrease in the process temperature and a corresponding increase in both the moisture content and the wet bulb temperature of the air passing through the cooling tower.
In areas like Tehran where access to water is limited, dry cooling techniques are used. As the name suggests, this relies on air as the medium of heat transfer rather than evaporation from the condenser circuit. Dry cooling means minimal water loss.
The ageing plant uses as much water as 70,000 people in the capital in a day. Per capita water consumption in Tehran is 250 liters a day.
“Another advantage of replacing the Besat Power Plant is less water consumption. The new station will save water use by over 90%,” Nasrollahi said.
Tehran has more than five million power subscribers of which 75% are households. At least 100,000 new customers join the subscription list every year that has grown at a regular pace piling pressure on utilities, namely water, electricity and gas.
Thermal Power Plants Holding Company oversees dozens of fossil fuel power plants with installed capacity of over 66,000 MW -- the bulk of electricity demand.
