Recently, Zhang Yangang, a senior engineer of Shougang International Engineering Co., Ltd., said that the cost of seawater desalination project at Shougang Jingtang Company is approximately 6 yuan per ton of water.

The Desalination Project of Shougang Jingtang Company started preparations in 2005. Given that it is the first seawater desalination project in the metallurgical industry, the steel plant has made land for sand blowing and is not aware of the seawater conditions in the surrounding sea areas. It dilutes the supply of finished products. Steel plant desalt users throughout the plant. In addition, combined with the fact that the iron and steel plant has residual heat, we designed a low-temperature, multi-effect process with a total size of 50,000 tons/day, which is divided into four units. Each desalination unit can be adjusted according to the change in water supply. The water yield of the equipment can be operated within the range of 50 to 100% of the rated capacity, which gives it great flexibility in operation and can be better adapted to the actual production needs of steel. In addition, the surplus steam from the steel plant can also be effectively used. Energy to avoid the emission of rich summer steam.

At that time, the construction of four sets of units was divided into two steps. The first step was to introduce two sets of units from SIDEM in France. On the basis of digestion and absorption of one-step units, the first step was to improve and give full play to the advantages of Shougang Group. Shougang International Engineering Co., Ltd. completed all the plant design and equipment sets. The mechanical manufacturing of the main evaporator was completed by Shougang Electromechanical Machinery Factory. The system debugging was completed by Shougang Jingtang Company.

The MED-TVC operating conditions were used in the initial stage of the unit's production, that is, the use of high pressure steam as the main power steam for the desalination unit, but we have always had an idea to reduce the pressure and temperature of the main power steam. Really less than 70 °C low temperature operation. In 2009, we embarked on the engineering transformation of the steam turbine generators for desalination plants.

The technology innovatively combines a low-temperature multi-effect device with a steam turbine and can directly utilize the low-temperature and low-pressure steam at the end of a steam turbine or other low-pressure steam source for desalination, and the process can still utilize other high-pressure surplus steam for seawater desalination. In addition, the system can also achieve desalination of steam from steam turbine exhaust steam and other high pressure steam. That is, it can not only run under TVC conditions, but also under pure MED conditions and MED+TVC conditions. Among them, under MED conditions, the cascade utilization of energy is fully realized, not only greatly reducing the operating costs of seawater desalination, but also generating additional power generation benefits.

The desalination combined power generation system was successfully put into operation in October 2011. The system can effectively regulate the balance of gas, steam, electricity and water in steel plants, fully embodying the concept of building a steel plant "circular economy, energy saving and emission reduction". The most notable feature of our Shougang Jingtang company desalination project.

The system operates under this operating condition, which can save the cost of water production; at present, the cost of our integrated water production (demineralized water) is approximately RMB 6 per ton of water, which is less than the cost per metric ton of water we purchased from externally purchased reservoir water. 3 yuan or so.

In addition, we have recently made efforts to further reduce the cost of sea water desalination through the innovation of systems and processes. We propose a few words: thermal membrane coupling, hydropower symbiosis, and now we are designing a second-phase 50,000-ton/day desalination project.

In the second phase of the project, we will further intensify innovation, mainly reflected in several aspects: First, to further optimize the seawater desalination cogeneration technology while achieving large-scale equipment; Second, the use of power plant DC cooling seawater thermal desalination; The third is the use of hot brine desalination; Fourth, the extraction of calcium and magnesium ions in concentrated brine production by-products; Fifth, the concentration of brine is sent to an external soda plant to achieve value-added; Six is ​​the desalination of different products of water For different applications, some products are treated with mineralization, disinfection, etc. to make domestic water, bottled or bottled drinking water for sale, and the industrial chain is prolonged. In response to the above process, we have carried out a period of trial work and we can say that it has achieved certain results. Our purpose is to reduce the operating costs of seawater desalination.

In addition, Shougang Group also planned the scale of recent and long-term seawater desalination at Shougang Jingtang Company. While ensuring its own needs, it also considers supplying water to the capital Beijing and its surrounding towns. The total planned construction scale is 4 million tons/day. We hope to contribute our efforts to ease the situation of the shortage of fresh water in China, especially in North China.