| Middle East Hassyan converted to gas
Dubai Electricity and Water Authority’s Hassyan power plant, once billed as state of the art clean coal, is well on its way to becoming 2400 MW (4 x 600 MW) of gas fired capacity. The second 600 MW unit has been commissioned and the third unit should enter commercial operation in the fourth quarter of 2022, with the fourth unit scheduled to be added in the third quarter of 2023. The US$3.2 billion facility, which is based on the IPP model (25
year PPA-BOO), employs GE (formerly Alstom) ultrasupercritical boiler technology and was initially designed as a dual-fuel power plant running on both natural gas and coal. In February 2022 the project company, Hassyan Energy
Company (51% DEWA, 26.95% ACWA Power, 14.7% Harbin Electric International and 7.35% Silk Road Fund) decided to convert the
project fully to natural gas, a conversion facilitated by the boilers already being designed for dual fuel operation. The plant is also required to be constructed carbon capture ready, “meaning that the installation of carbon capture equipment in the future should be without the need for any modification to the plant or hinder plant availability.” The EPC contractors are GE and Harbin Electric International.
NOMAC is the O&M contractor. The Hassyan power complex includes a water desalination
Hassyan, as originally envisaged, a benchmark for clean coal
facility with a production capacity of 120 MIG (million imperial gallons) per day using reverse osmosis (RO), operating on the independent water producer model. The Hassyan power complex, along with the Jebel Ali power plant and water desalination complex, are the two key pillars of Dubai’s electricity and water infrastructure. Jebel Ali, as verified by Guinness World Records, has the distinction of being the largest single-site water desalination facility in the world, with a production capacity of 490 MIG/ day, and the world’s largest single-site natural gas fuelled power generation facility, with an installed capacity of 9547 MW. DEWA’s total installed capacity is currently 13 417 MW, which includes 1527 MW of PV in operation at the Mohammed bin Rashid Al Maktoum solar park.
A major milestone for project was achieved in July 2022, when the first salts, at around 290°C, were injected into the receiver. Heating of the salts was then progressively increased by focusing more and more of the heliostats on the receiver in order to reach the required 565°C at the receiver outlet. The solar thermal receiver is “impressive both in terms of its dimensions and its capabilities”, says John Cockerill, “a giant interlacing of pipes, tanks and heat exchangers.” It weighs around 1500 tons and is itself about forty meters high, located within the 262 m central tower. John Cockerill describes itself as “the world’s leading supplier of molten salt solar receivers”, with five reference projects, including DEWA IV and a 2021 contract for design and supply of a receiver for a CSP project in South Africa.
Parabolic-trough CSP
The parabolic trough collectors (arranged in three groups, 200 MW each) track the sun from east to west to maximise the electricity generation. At their focus they have absorber tubes through which the heat transfer fluid (HTF) circulates. This fluid consists of a eutectic mixture of diphenyl and biphenyl oxide (type Therminol VP1, Dowtherm A or equivalent) with a freezing temperature of around 12°C.
The parabolic trough collectors raise the temperature of the heat transfer fluid up to 393°C. The energy contained in this fluid is transferred directly to a steam generator or it can be sent to a thermal storage system (two molten salt tanks) where it is kept for later use. The parabolic trough power generation system can be operated in different modes. In the direct operation mode, the heat transfer fluid flows from the solar field to the solar steam generation system where main steam is produced at a temperature of around of 380°C and a pressure
of 100 bar, passing the fluid through different (or just one) parallel trains of heat exchangers, each one composed of three heat exchangers connected in series (preheater, evaporator and superheater).
A train of heat exchangers in parallel is used to produce reheat steam. The heat exchangers cool the HTF and send it to the solar field to be reheated. Surplus energy is sent to the thermal energy storage system.
The steam–water cycle is a classical Rankine regenerative cycle with reheat.
An auxiliary PV system is connected to the CSP electrical auxiliaries busbar to supply auxiliary power during the day.
Photovoltaics dominant The 250 MW of PV included in Phase IV is split into two PV plants. One is adjacent to the heliostat field of the central tower. This has a
net export capacity of 217 MWac. The second, a smaller PV installation, with a net export capacity of 33 MWac, is adjacent to the parabolic trough area.
The 13 MW photovoltaic first phase of the solar park became operational in 2013. The 200 MW second phase, also PV, was commissioned in March 2017. The photovoltaic third phase has a capacity of 800 MW. A power purchase agreement was signed in March 2020 for the 900 MW photovoltaic fifth phase.
In October 2022, expressions of interest were invited by DEWA from international developers for phase 6, a further 900 MW of PV, due to become operational in phases, starting from Q3 of 2025. Overall, the Mohammed bin Rashid Al Maktoum facility is the largest single-site solar park in the world based on the IPP model, with a planned capacity of 5000 MW by 2030 and total investments of up to AED 50 billion.
Steam turbine
Generator Hot salt tank Boiler Condenser
Cold salt tank Simplified schematic of parabolic-trough CSP (source DEWA)
www.modernpowersystems.com | October 2022 | 39
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