【Major Chemical Equipment in China】093 – China’s First Large-Scale Thermal Membrane Coupled Seawater Desalination Project
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The past decade has been a period of rapid development in China’s chemical industry, marked by the emergence of many new processes, products, and equipment. There has also been significant progress in China’s chemical processing equipment, which has contributed to the swift advancement of the petrochemical sector. Here, we have compiled some of the achievements and breakthroughs made by Chinese equipment manufacturers in terms of larger-scale production and increased use of domestic equipment. We invite everyone to share their insights and discuss these topics together; let’s cheer for Made in China and support the development of chemical processing equipment! *********************************** At 12:30 on December 16, 2020, after 48 hours of stable trial operation, China’s first heat-membrane coupled seawater desalination project was officially put into use at Shougang Jingtang (as shown in the figure). It is reported that this project can produce 10,000 tons of fresh water per day. As a result, the daily seawater desalination capacity of Shougang Jingtang Company has reached 95,000 tons, enabling the company to meet over 70% of its water needs internally, and it can save approximately 40 million tons of surface water resources each year.
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Common seawater desalination methods are divided into thermal and membrane methods. ‘The ‘thermal method’ involves using the waste heat steam from steel mills to heat seawater; distilled water is obtained after the seawater evaporates and condenses ； ‘The ’membrane method’ uses ultrafiltration membranes and reverse osmosis membranes to filter out fresh water while retaining saltwater, similar to household water purifiers. ”Zhang Bo, head of the Energy and Environmental Protection Department at Shougang Jingang Company, explained that since the implementation of the seawater desalination project, the company has built a thermal seawater desalination facility capable of producing 85,000 tons of fresh water per day. Together with gas-fired combined cycle power generation units, this has enabled the creation of the world’s first high-efficiency integrated recycling system that combines combustion, heat generation, electricity production, water production, and salt recovery in one process. The newly commissioned heat-membrane coupled seawater desalination project represents a further extension of the \"five-in-one\" concept. The project consists of 6 ultrafiltration units, 3 seawater reverse osmosis units, as well as cleaning and backwashing facilities, and is capable of producing 10,000 tons of fresh water per day. The heat-film coupled seawater desalination unit operates in series with the previously built thermal seawater desalination units, using the concentrated brine obtained through thermal distillation as the feed water, which makes it more environmentally friendly. The fresh water obtained through seawater desalination is used for circulating cooling in the smelting process of the company’s high-end products as well as for the daily drinking of employees. At the same time, Shougang Jingtang Company sells the remaining concentrated brine to companies such as Tangshan Sanyou Group for use in producing chemical products like soda ash. This not only reduces the overall cost of seawater desalination but also creates a circular economy industrial chain, yielding social benefits for all parties involved.
High energy consumption in seawater desalination technology and high prices of fresh water are among the main barriers to its widespread adoption and application. Conducting research on energy savings and reduction in the seawater desalination process is of great significance for promoting economic development and meeting societal needs. This project aims to integrate thermal and membrane desalination technologies from the perspective of process integration. It will study the matching techniques for thermal-membrane coupling as well as the planning and scheduling techniques for co-production of water and electricity. By utilizing flow distribution nodes and mixing nodes, an superstructure representation method for thermal-membrane coupled seawater desalination systems will be developed. Meanwhile, taking into account factors such as membrane fouling, cleaning, and replacement strategies, as well as the spatiotemporal characteristics of seasonal changes, variations in water sources, and electricity demand, an optimization design model for a thermal-membrane coupled seawater desalination system that meets various water quality requirements and accounts for water source supply will be established. A hybrid genetic-annealing random optimization algorithm combining simulated annealing and genetic algorithms will be developed, with parameters such as the number of desalination stages, the number of membrane modules, and flow fractions serving as optimization variables. Software integration techniques will be used to combine the optimization algorithm with process simulation in order to solve the optimization design model, thereby proposing an optimization design method for a thermal-membrane coupled seawater desalination integrated system that takes into account the planning and scheduling of co-production of water and electricity.
Overall, what is the unit price per ton of water?