What processes are generally used for desalinated water in coal chemical industries?

The brief description is as follows: 1. Traditional process: the ion exchange water production process, which uses ion exchange resins for desalination. The cost of tons of desalinated water is generally around 2 yuan, but due to significant variations in the analysis data of the raw water, especially in terms of hardness and turbidity, the costs can vary greatly as well. The ion exchange process is further divided into fixed-bed and floating-bed types based on the structure of the anion and cation beds. 2. The commonly used process nowadays is reverse osmosis (RO) + mixed-bed process. Its advantages are small floor space and simple operation ； No environmental pollution, reduced waste disposal costs, and easy scale expansion ； The cost of water production is low, at around 1.0–1.5 yuan per ton (depending on the quality of the raw water). The downside is that the water recovery rate is around 70%, resulting in significant water waste, as well as high initial investment costs.

Currently, the main methods for water treatment are ion exchange and reverse osmosis, with some applications also combining both. It can be said that reverse osmosis is simple to operate and produces water of good quality; under normal conditions, the conductivity is below 8, which is sufficient for industrial use. If higher standards are required, a mixed-bed system needs to be added. In terms of investment, I think it’s not much higher than that of traditional ion exchange methods; the investment per ton of water is around 20,000 yuan. The problem is that the lifespan of reverse osmosis membranes is short, at most 5 years, and the water utilization rate is low, around 70%. The wastewater can be used for irrigation purposes.

There are methods such as multi-stage flash distillation, membrane separation, and direct distillation; among these, multi-stage flash distillation is the cheapest, with costs of around 5 to 6 yuan per cubic meter