Polymer Preparation System

Polymer Preparation System

The kind of Polymer that usually used in water and waste water treatment is Anionic Polymer. Anionic polymerization is a type of chain growth polymerization in which an anionic initiator transfers a charge to a vinyl monomer which then becomes reactive. Each reactive monomer goes on to react with other monomers to form a linear polymer.

Let RMe be an organometalic compound such as butyl lithium (LiC4H9) that initiates polymerization and M a monomer, then the individual steps can be represented as follows:

RMe ⇔ Me+ + R-             R=chemical group"gugus".     M=Monomer, from feed water also.

R- + M → RM-

RM- + M → RM2-

RMn-1- + M → RMn-

The polymerization only stops when all monomers are consumed. For this reason, this type of polymerization is often called anionic "living" polymerization.

Anionic polymerization include -CN, -COOR, -C6H5, and -CH=CH2 → group"gugus".

Now discuss about polymer preparation system.

Polymer chemical dosing or preparation is controlled automatically. This control box is connected with liquid meter  (level transmitter) on the solution tank. Once the liquid meter reaching "the low level" it will touch and open the inlet solenoid valve. At the same time, start up the unit and start to prepare the chemical (polymer). The volume of dosage and water volume can be selected correctly. This will obtain the accurate concentration. For water or waste water treatment, the polymer solution is around 0.1% until  0.2 %. On the other hand, the liquid meter reach the "high level and its cycle process will stop while the agitator is still working.

figure 1. polymer preparation system

The main component of polymer solution system:

1. Vacuum feeding machine to transfer dry polymer powder from polymer bag to screw          feeder. It has air purifier, the whole operating process should be dust-free.                          2. Chemical dosing unit consisit of screw feeder (conveyor) which to transport the dry polymer powder out of the hopper totally. At the conveyor outlet, there is electric heater unit to prevent the moisture invading into the powder. The hopper volume is 60 liters.                  3. Dry powder pre-soaking device adopt rotating water and injection water, which can mix and soak the dry powder totally, then enter into the premixing tank.                                      4. Tank: three-tank integration, including premixing tank, homogenous matureing tank and solution storage tank. There are baffle plate and overflow weir plate among different tanks. During the chemical preparation, the chemical solution should flow from baffle plate bottom into the next tank via V type overflow weir plate. There is concealad overflow pipe in the pre-mixing tank, which is used for preventing the liquid overflowing when the liquid level acess the set point (breakdown).                                                                                                  

5. Liquid level controller, the location is in the solution storage tank to control high/low/ultra-low level point.                                                                                                    6.  Agitator, there are agitators on the top of pre-mixing tank and mature tank. It can not only promise uniform solution, but also not damage to the polymer molecule.                        7. On-line dilution system, it's the source of water for dilute the dry polymer powder. It's consist of filter,pressure gauge,elbow,solenoid valve, manual stop valve,flow meter.        

8. Electric control cabinet: PLC cabinet is equipped with auto electrical elements, including manual/auto knob.