What is antiscalant chemical for ro plant
The reverse osmosis system is mainly used to make pure water, which is composed of reverse osmosis membrane (RO), high-pressure pump and security filter set to protect the reverse osmosis membrane.
During daily operation, due to the existence of raw water metal, the reverse osmosis membrane has the risk of scaling. We need to add water treatment agent, that is, antiscalant chemical for ro plant.
Reference resources
Action mechanism of antiscalant chemical for ro plant
1. Scale inhibition mechanism
The agent can form calcium carbonate and magnesium hydroxide precipitates with deformed lattice structure with scaling substances (calcium and magnesium ions) in water. Under the condition of high water alkalinity, water slag is formed and then discharged through sewage discharge. To achieve the purpose of scale inhibition.
2. Anti scaling mechanism
After the agent is dissolved in water, a colloidal anion is formed. This colloidal anion can adsorb suspended solids and calcium and magnesium ions in water and form colloidal particles, which are not easy to deposit on the pipe wall and easy to be discharged out of the system. Because colloidal anion inhibits and disperses the formation and deposition of scale such as carbonate and sulfate, scaling can be prevented after long-term use.
3. Anti corrosion mechanism
As the suspended solids and calcium and magnesium ions in circulating water are easy to deposit on the pipe wall and are not easy to be discharged out of the system, the suspended solids and calcium, magnesium ions, sulfate, silicate and other scale in water have corrosive effect. Therefore, the agent has achieved the above scale prevention and scale inhibition effect and formed a protective film, so as to achieve the anti-corrosion effect. The experiment and user’s practice show that the corrosion inhibition rate reaches (FE) ≥ 99%.
Dosing of antiscalant chemical for ro plant
The input mode of reverse osmosis antiscalant chemical for ro plant. is generally a special dosing tank, which will be added to the raw water regularly and quantitatively. The dosing point of reverse osmosis antiscalant chemical for ro plant. is generally added before the filter. Dosing dose mainly depends on whether the flow of reverse osmosis equipment is directly proportional. Generally, the addition amount of reverse osmosis antiscalant chemical for ro plant. is 2-6ppm.
Before adding reverse osmosis antiscalant chemical for ro plant., we should ensure that it is compatible with the added flocculant, otherwise the reverse osmosis membrane may be blocked.
How to add antiscalant chemical for ro plant
- Clean the dosing box for the first time.
During cleaning, close the blowdown valve at the bottom of the dosing tank, open the blowdown valve after water injection and cleaning to drain the water, and start dosing after cleaning twice.
- Adjust the dosing stroke of the metering pump
Turn the stroke adjustment knob of the metering pump counterclockwise to the corresponding scale.
- Dispensing
Check and close the blowdown valve at the bottom of the dosing tank, and calculate the dosage of ptp-0100 according to the effective volume in the dosing tank and the actual working output of the metering pump. Add chemicals from the dosing port of the dosing tank, open the water inlet valve to dilute to the maximum liquid level scale, and close the water make-up valve.
For example, the reverse osmosis feed water flow is 160m3 / h and the metering pump flow is 22L / h. If the stroke of the metering pump is adjusted to 40%, the actual output is 22L / h × 40%=8.8 L/h
The effective volume of the dosing box is 600 liters.
The volume of ptp-0100 concentrate to be added into the dosing tank:
- Turn on the mixing motor of the dosing tank, mix the reagent evenly, and then stop the motor.
- Open the inlet and outlet valves of the metering pump, open the metering pump switch, and add the reagent in front of the security filter. After the RO stops, close the metering pump.
- Regularly inspect the dosing system for leakage, and solve the leakage in time. Check whether the dosing amount of the metering pump is accurate, whether the liquid level drop of the dosing tank is consistent with the calculated dosing amount of the metering pump, and if not, calculate and adjust it in time.
- Record and check whether the total water inflow and dosage match each month.
- Pay attention not to exceed the maximum liquid level when replenishing water in the dosing tank.
- When the dosing tank is set with low liquid level alarm, if the central control PLC is set to low liquid level alarm, stop the dosing pump and switch to the standby dosing tank and metering pump for dosing. When ptp-0100 solution is configured for the second time, the volume of dosing tank is calculated based on the actual volume.
If the diameter of the dosing box is 1m, the actual volume is:
V=S × h= Л R2h=3.14 × zero point five × zero point five × H = 0.785h (L)
Types of antiscalant chemical for ro plant
Common antiscalant chemical for ro plant.s include polyphosphate, organic phosphate and polycarboxylic acid. Such antiscalant chemical for ro plant.s include sodium hexametaphosphate SHMP and sodium tripolyphosphate. Polyphosphate antiscalant chemical for ro plant. is easy to hydrolyze into orthophosphoric acid in acidic system and high-temperature water system to form secondary scaling of ca3po42.
On the other hand, polyphosphate is a nutrient source for microorganisms, which can promote the growth of bacteria and algae and accelerate membrane pollution. This kind of agent has no effect on CaSO4 scale inhibition. Therefore, this kind of antiscalant chemical for ro plant. has been rarely used and is gradually replaced by other antiscalant chemical for ro plant
1. Organic phosphate
Organic phosphates inhibit scale mainly by slowing down crystal growth and lattice distortion. The simultaneous existence of these two effects also makes this kind of agents have threshold effect. The combination of organic phosphate and other antiscalant chemical for ro plant.s also has good synergistic effect. Organic phosphate antiscalant chemical for ro plant.s commonly used in reverse osmosis system include ATMP, HEDP, PBTCA, etc
2. Phosphorus containing organic compounds
Among the organic compounds containing phosphorus, the organic compounds with phosphate group are called phosphonates for short. Typical antiscalant chemical for ro plant.s include phosphonates such as ATP, HEDP and PBTC. In water systems with many calcium ions, it is also easy to form insoluble calcium salts and completely lose the scale inhibition effect.
Phosphorus containing antiscalant chemical for ro plant.s are hydrolyzed due to biological effects and finally become phosphate ions. In addition to calcium phosphate scaling, they often become a cause of eutrophic water pollution.
3. Low molecular weight carboxylate
In recent years, polymer antiscalant chemical for ro plant. with carboxyl groups without phosphorus and environmental pollution have been widely used. The typical monomers of such polymers are acrylic acid, methacrylic acid, maleic acid, fumaric acid, 2-methylene succinic acid, etc. Generally speaking, low molecular organic compounds with carboxyl groups have scale inhibition effect.
The above organic antiscalant chemical for ro plant.s need to use various antiscalant chemical for ro plant.s with different structures according to the type of scale treated and water quality. In addition, even if the water quality changes greatly, the stable scale inhibition effect can be obtained, and the treatment methods of agents with different structures can be adopted at the same time.
If the dosage of antiscalant chemical for ro plant.s such as condensed phosphate and organic phosphonate is insufficient, scale will adhere when the scale composition exceeds the critical concentration due to the change of water quality. Carboxylic acid antiscalant chemical for ro plant.can inhibit precipitation and have a strong dispersion effect on precipitated particles.
Therefore, it can be used as a antiscalant chemical for ro plant. with a wide range of application. If the condensed phosphate and organic phosphonate antiscalant chemical for ro plant.s are combined with low molecular polymer antiscalant chemical for ro plant.s, the secondary scaling of calcium phosphate can be prevented, and the attached particles precipitated when the critical concentration is exceeded due to the change of water quality can be inhibited.