The desalinated water for power plant boilers is obtained by using cation anion exchange resin to obtain deionized water. Generally, after passing through it, the conductivity of the effluent can be reduced to below 10us/cm, and then it can reach below 1us/cm through a mixed bed. However, the water produced by this method has a high cost and too many particle impurities, which cannot meet the ideal requirements. Currently, it is less commonly used.

2、 Introduction to desalination process for power plant boilers

The first type: pre-treatment (i.e. sand carbon filter+precision filter)+reverse osmosis+mixed bed process

This method is currently widely used because the investment cost of reverse osmosis is not high. It can remove 90% of the ions that have already been added to the water, and the remaining ions can be removed through mixed bed exchange. This can increase the effluent conductivity to around 0.06. This is currently a popular method.

The second method is to use reverse osmosis for pre-treatment, just like the second method, except that the mixed bed used later uses EDI continuous desalination membrane blocks instead, so that acid alkali regeneration resin is not used, but electric regeneration is used. This completely eliminates pollution throughout the entire process, and the treated water quality can reach over 15M. But this method requires more upfront investment and lower operating costs.

3、 Desalinated water equipment EDI

Desalination water equipment EDI: It is an advanced technology that integrates ion exchange technology and electrodialysis technology. It achieves directional migration of ions under the action of a direct current electric field. The system uses a direct current electric field to selectively permeate anions and cations through anion and cation exchange membranes, as well as ion exchange resin to exchange ions. In addition, water self electrolyzes into H+OH - to complete continuous automatic regeneration of the resin, thereby achieving deep desalination of water. The system does not need to stop using acid-base regeneration resin, and can continuously produce high-quality pure water.

4、 Characteristics of desalinated water from power plant boilers

1. The length of the equipment operation cycle and the amount of salt input can be adjusted according to the hardness of the raw water. The resin dosage is small, the salt consumption is low, the water quality is excellent, the operation is simple, and the maintenance is convenient.

2. The equipment has strong adaptability, and the residual hardness of softened water after one softening of high hardness raw water (≤ 28mmol/l) is ≤ 0.03mmol/l.

3. The equipment continuously produces water without the need for a backup exchanger, and does not require the installation of a salt tank, salt pump, or pressure salt container.

4. The equipment is lightweight, occupies a small area, does not require a dedicated factory building, does not require a concrete foundation, and has low costs for civil engineering, procurement, installation, operation, and maintenance.

5. The equipment has been filled with resin before leaving the factory, making installation easy. Simply connect the inlet and outlet pipes and power supply to start producing soft water.

6. The energy-saving effect of the equipment is significant. Compared with similar products, it saves 50% of investment, 30% of salt, 60% of cleaning water, and reduces environmental pollution.

5、 Process of desalinated water equipment for industrial boilers

Backwash: After working for a period of time, the equipment will intercept a lot of dirt brought by the raw water on the upper part of the resin. After removing these dirt, the ion exchange resin can be fully exposed, and the regeneration effect can be guaranteed. The backwashing process is when water is washed in from the bottom of the resin and out from the top, which can wash away the dirt intercepted at the top. This process usually takes about 5-15 minutes.

Salt absorption (regeneration): The process of injecting salt water into a resin tank. Traditional equipment uses a salt pump to inject salt water, while fully automatic equipment uses a dedicated built-in sprayer to suck in salt water (as long as the inlet water has a certain pressure). In practical work, the regeneration effect of salt water flowing through the resin at a slower speed is better than simply soaking the resin in salt water. Therefore, softening water equipment adopts the method of slow flow of salt water through the resin for regeneration, which generally takes about 30 minutes. The actual time is affected by the amount of salt used.

Slow flushing (displacement): After flowing salt water through the resin, the process of slowly flushing all the salt in the resin with raw water at the same flow rate is called slow flushing. Due to the fact that a large number of calcium and magnesium ions on functional groups are still exchanged by sodium ions during this flushing process, according to practical experience, this process is the main process of regeneration, so many people call this process displacement. This process is generally the same as the salt absorption time, which is about 30 minutes.

Quick flushing: In order to thoroughly flush away residual salt, a flow rate similar to actual work should be used to flush the resin with raw water. The effluent from this process should be soft water that meets the standard. Generally, the fast flushing process takes 5-15 minutes.