Designing cooling towers for the Asia-Pacific market requires a host of specific considerations. Marianna Caputo details what’s involved.
The Asia-Pacific region is committed to setting up sustainable energy investments based on a generation mix featuring a larger portion of renewables. The emerging economies across Southeast Asia are facing a dynamic demand for power with minimal impact on the environment, and the conventional power generation industry is still considered a dominant energy source. In this scenario there is colossal potential for companies that can deliver eco-friendly, cost-efficient and reliable technology to fuel steep regional economic growth.
SPIG is bringing its environmental solutions to four Asian countries, and is currently committed to delivering wet/dry (hybrid), sea water, low noise cooling towers and air cooled condensers for a diverse range of major power generation and oil refining projects. These have been exported to the dynamic Southeast Asian region with the support of the 1220 MW Pengerang cogeneration plant in Malaysia. In addition, SPIG cooling technology is being utilized at the 800 MW Wyrie combined heat and power plant in South Korea, as well as at the Kumho petrochemical plant at the Nghi Son oil refinery in Vietnam.
Early this year, Siemens awarded SPIG contracts for the cooling towers for Pengerang and Wyrie respectively. Pengerang Integrated Petroleum Complex will include a customized sixteen-cell back-to-back configuration, fibre reinforced polyester (FRP) frame construction cooling tower. The FRP technology is impervious to a broad range of corrosive substances and harsh environments and immune to deterioration. FRP pultruded profiles resist UV rays, acid rain, sand storms, salt water and chemicals.
The mix of polyester resin deployed for the profiles, considered a strong and maintenance-free material, ensures long-life operation of this cooling tower. The Pengerang FRP cooling tower is even considered eco-friendly, as it does not need any repellent in comparison to a wooden type.
The Pengerang cooling tower, which is currently under construction, will cool a cogeneration plant that will serve the RAPID refinery and petrochemical integrated development mega-project. Once completed, RAPID will be an important and strategic achievement in light of the dynamic developments undertaken by the Malaysian government.
In order to respond to localization requirements, SPIG has agreed on defined milestones with the client to source materials locally and to proactively set up a service hub. A service management team will ensure availability of spare parts and general service provisions. Moreover, SPIG plans to incorporate SPIG Malaysia and complete the lease of a local warehouse and facilities.
Designing the towers
In the same year, Siemens awarded SPIG the detailed structural design and material supply for the Wyrie wet/dry technology cooling tower, planned to be commissioned in December 2017. The SPIG plume abated customized cooling tower will be specifically designed to avoid visible plume in cold and humid climate, in order to meet specific and very severe no plume (DBT -6°C; RH 70 per cent) requirements.
This wet/dry cooling tower is the first of its kind in the world deploying a unique water distribution system. Designed with customized features, the tower will have an internal concrete riser/by-pass duct distribution system in lieu of an external FRP/steel piping system. Moreover, the cooling tower has been designed to operate on a completely automatic mode, as a ‘black box’. In fact, it is equipped with rolling doors on the wet air inlets, dampers on the dry inlet, two-speed motors and a weather station to allow automatic operation during different ambient conditions.
SPIG was also involved in the Siemens 145 MW S1 combined heat and power project to design an air cooled steam condenser which will be in operation in the second half of 2015.
The air cooled condenser does not need water to condense the steam and is therefore a sustainable choice for arid regions suffering from water scarcity or countries where stringent environmental legislation does not allow the use of water for industrial purposes.
While conceiving the nine-section A-frame air cooled condenser, which will be installed on a 26 metre-high rooftop, SPIG engineers have to consider severe restrictions on plot area in the overall design.
In 2014 GS E&C selected SPIG to design and supply two sea water fibre reinforced polyester cooling towers for the 200,000 barrel-a-day Nghi Son refinery, 180 km south of Hanoi.
The corrosion-free solution, suitable for a harsh environment, is equipped with duplex hardware and a back-to-back arrangement. Each tower will process 66,550 m³ of sea water per hour, for a total of 133,100 m³/hour. The two units will come online in the first half of 2016.
This contract award demonstrates that the use of sea water as make-up is a feasible key solution when water shortage is an issue. Using sea water, the engineering team has to select special materials.
In fact, the best choice is the use of corrosion-free plastic materials for the cooling tower structure and the main internal components. The mechanical equipment will be protected with a coating suitable for salt water applications. The steel parts are of high grade stainless steel (“Duplex” EN 1.4462 and AISI316) or special alloy (Silicon Bronze, Aluminium Bronze). The two cooling towers will be designed according to the main applicable international standards such as CTI, ASME, etc.
SPIG engineers will utilize the high efficiency H-MOON drift eliminator. This dispersion technology aims to maximally reduce the dispersion of salt water droplets carried over by the cooling air leaving the tower. The H-MOON will reduce the percentage of water loss, preventing quick deterioration, corrosion of the surrounding equipment and environmental pollution. A further project requirement is the stringent noise restriction set at 82 dbA and satisfied by carefully selecting each mechanical component.
This is the largest sea water cooling tower project to be executed for a highly complex refinery, one of the country’s largest and most important projects designed to supply the growing Vietnamese domestic market.
As the environment is a prominent concern even in emerging markets, when comparing wood and FRP as materials for cooling tower construction it should be noted that the latter is much more sustainable. Unlike wood, FRP requires no environmentally unfriendly preservatives or repellants. FRP shapes and plate are inert and do not release toxic chemicals, and therefore they are easily disposable in landfills. Treated wood has been banned for several applications as extreme care in use and disposal is required.
Also on the environmental front, sea water cooling towers equipped with the latest dispersion technology are key to saving water and safeguarding the delicate marine ecosystem by helping to control drift losses and water discharge temperature. Similarly, wet/dry cooling technology is the preferred choice to guarantee water saving when abating a visible plume of vapour in cold and humid climatic conditions.
In addition, the use of energy efficient, low-noise fans results in power saving, helping to reduce an installation’s carbon footprint as well as abating noise. The noise generated by the fan and the water flowing through the tower into the basin must remain within certain limits. A suitable remedy includes deploying ultra-low-noise fans and designing a floating noise attenuation system to be installed within the basin. Customized measures such as inlet silencers, outlet silencers and soundproofing boxes encapsulating the motors are normally considered viable solutions for sound pollution.
The need to save water resources, especially where water is a scarce commodity, has become an increasingly sensitive issue. SPIG dry cooling systems, also known as air cooled condensers, are manufactured with single row aluminium brazed tube technology, guaranteeing high performance in the process of condensing the turbine exhaust steam and providing significant benefits due to higher reliability and lower power consumption. Single row tube deploys the greatest extended surface within the industry, resulting in fewer cells installed.
Installation of FRP cooling tower in Vietnam
Nghi So refinery project
Credit: GS E&C
Customers deploying air cooled condensers may benefit from water savings, environment preservation thanks to these emission-free systems, and lack of hot water discharge into the sea or rivers.
R&D for the future
The expected increase in worldwide energy demand is set to boost the deployment of dry cooling systems technology, mainly in regions which suffer from water shortages. In Asia this growth will be supported by SPIG’s Indian and Chinese branches and production facilities, as well as its Korean operation. In China, SPIG has established a new production line for air cooled vacuum condensers single row tube bundles. A mostly automated process is qualified according to the ISO 9001:2008 standard and complies with international standards concerning sustainable development. Quality control and assurance is directly managed and tested by SPIG.
Moreover, through an active R&D department, product innovation and development with the aim of satisfying global project requirements are undertaken at SPIG’s research and test facilities in Italy. At these specialized centres of excellence, a team of R&D and testing engineers conducts thermal performance research as well as development and testing activities for fills, nozzles and drift eliminators.
The facilities are specifically designed for cooling tower testing and analysis, and can simulate a wide range of conditions with the support of Unico technology, a customized Unique Online Continuous Monitoring System designed to improve overall plant efficiency by checking process parameter variability and equipment reliability.
Marianna Caputo is Marketing Manager at SPIG SpA