Ion exchange equipment
Ⅰ、Product overview
Ion exchanger is divided into: sodium ion exchanger, yin-yang bed, mixed bed and so on. The shell of ion-exchange column (device) is generally made of hard polyvinyl chloride (PVC), hard polyvinyl chloride composite glass fiber reinforced plastic (PVC-FRP), organic glass (PMMA), plexiglass composite transparent glass fiber reinforced plastic (PMMA-FRP), steel lining adhesive (JR), stainless steel lining adhesive and other materials。
Ⅱ、Use
Ion exchanger is mainly used for the preparation of pure water and high pure water, and has been widely used in many fields such as medicine, chemical industry, electronics, painting, beverage and water supply of medium and high pressure boiler. It can be used for the pretreatment of boiler, thermal power station, chemical industry, light industry, textile, medicine, biology, electronics, atomic energy and pure water treatment, the occasions where hard water softens and deionized water is prepared for industrial production, it can also be used for the decolorization and purification of food and drugs, the recovery of precious metals and chemical raw materials, the treatment of electroplating wastewater, etc.
Ⅲ、Classification
Sodium ion exchangers: mainly used in boiler, thermal power station, chemical industry, light industry, textile, medicine, biology, electronics, atomic energy and pure water treatment of the front treatment.
Yin-yang bed: Yin-Yang ion exchange bed is also a compound bed, which is used in series by Yang and anion exchange device to achieve the purpose of water desalination.
Mixing bed: The mixing bed is to fill the anion exchange resin in the same ion exchanger in a certain mixing ratio. After the mixed ion exchange, H ions and OH ions entering the water immediately generate water molecules with a very low ionization degree, which can make the exchange reaction proceed very thoroughly. After the mixed bed is set up, the water quality is further purified. When water quality requirements are not high, can also be used alone。
Ⅳ、The working principle
It works by ion exchange.
Running time: positive resin (H-R)+(M+)-->:(M-R)+(H+)
Yin resin(OH-R)+(X-)-->:(X-R)+(OH-)
Where M+ is the metal ion and X- is the anion.
The regeneration process is the reverse process.
Failure control of ion exchanger
The simplest process of ion exchange desalination is the first stage multiple bed desalination system consisting of a positive bed and a negative bed. Some primary compound bed desalting system adopts unit system, namely each primary compound bed desalting system includes positive bed, (carbon eliminator), negative bed each one, in the ion exchange desalting operation process, whether the positive bed or the negative bed first failure, is simultaneously regeneration; There is also a level of double bed salt removal system using the mother control, that is, the positive bed and the positive bed or the negative bed and the negative bed is parallel operation, which one of the exchange failure on the regeneration of which one.
1 Principles of detection and control
The adsorption order of strong acid positive resin to various cations in water is as follows:Fe3+>Al3+>Ca2+>Mg2+>Na+>H+. ;Therefore, the adsorption capacity of metal ion Na+ in water is the weakest, so when ion exchange occurs, various ion adsorption layers in the resin layer gradually move down, H+. Finally replaced by other cation, when the protective layer penetrates, the first leakage is the lowest layerNa+;Therefore, the standard to monitor the failure of cation exchanger is sodium leakage. The reaction equation is (A represents the metal cation,R represents the resin group):
An+ +nRH=RnA+n H+
HCO3- + H+ =H2O+CO2↑
The adsorption sequence of various anions in water by strongly alkaline negative resin is as follows:SO42->NO3->Cl->OH->HCO3->HSiO3- 。It can be seen that HSiO3- has the weakest adsorption capacity, so when ion exchange occurs, various ion adsorption layers of the resin layer gradually move down.OH-.Replaced by other anions, when the protective layer penetrates, it is the lowest layer that leaks out firstHSiO3-;Therefore, the standard to supervise the failure of anion exchanger is silicon leakage. The reaction equation is (B stands for acid anion and R stands for resin group):
Bm- +mROH=RmB+mOH-
2 Control points and control methods
Since the master control system includes a unit system, and it has the advantages of fully using resin, improving the water discharge capacity of the exchanger, and reducing acid and base consumption, etc., we mainly discuss the ion exchange desalination system based on this structure in our study.
With the chengdu institute of biological products protein extraction workshop pure water station as an example, the system of mother tube water treatment system, the structure of the system is: the sand filter, activated carbon filter - coarse filter - Yang bed - a Yin Yin - two - mixed bed - - pure water tank, fine filtration system water production capacity of 5 t/h, in system failure control research, we propose a unit failure control concept, also is to make full use of advantages of mother tube water making system failure control system.
(1)ROThe removal rate of each organic solute was higher than that of NF membrane。(2)The removal rates of different organic solute were different, and some were even quite different (for example, the absorbance removal rates of RO and NF membranes for acetic acid were 95.34% and 81.45%, respectively, while the absorbance removal rates of p-aniline were 61.50% and 46.82%, respectively).
3 Effluent water quality
The electrical conductivity (25℃) of raw water is lower than 10 after desalination in a first stage rebedμS/cm，The silicon content in water is lower than100μg/L
