Scale inhibitor: insoluble in waterinorganic salt, prevent or interfere with the insoluble inorganic salt on the metal surfaceprecipitate、ScalingFunction and maintain good heat transfer effect of metal equipmentmedicament。
The scale inhibitor can remove the scale and prevent the formation of scale, improve the heat exchange efficiency, reduce power or fuel consumption;Water treatment can also reduce pollution discharge and improve water utilization, which can generally save more than 60%, in line with China's new policy of energy conservation and emission reduction.[1]
Chinese name
Scale inhibitor
Foreign name
scale inhibitor
Functional characteristics
Applicable to various membrane tube materials
Part
Chelation, dispersion and lattice distortion
Policy support
conserve energy ,reduce emissions
Function classification
Solubilization, condensation and dispersion, electrostatic repulsion, crystal distortion
From the perspective of action mechanism, the role of scale inhibitor includes chelating solubilization, coagulation and dispersion, electrostatic repulsion and crystal distortion.[1]In the laboratory evaluation test, dispersion is the remedial measure for chelation, and lattice distortion is the remedial measure for dispersion.
Chelation
From the central ion and some of the sameMultidentate ligandThe process of complex with ring structure formed by the bonding of two or more coordination atoms is called chelation.As a result of chelation, scaling cations (such as ca2+,Mg2+, etc.) reacts with chelating agent to form stable chelates, thus preventing it from being mixed with scaling anions (such as CO3 2-，SO42-，PO43-，Contact with SiO32 -, etc.) greatly reduces the probability of scaling.[1]Chelation is stoichiometric, for example, one EDTA molecule chelates one divalent metal ion.
The chelating ability of chelating agents can be expressed by the calcium chelating value.Generally, the chelating capacity of commercial water treatment agents (the mass fraction of active components of the following agents is 50%, and the chelating capacity is calculated by CaCO3):Aminotrimethylene phosphonic acid(ATMP)—300 mg/g;Diethylene triaminePentamethylenePhosphonic acid (DTPMP) - 450 mg/g;EDTA(EDTA) - 15 om g;Hydroxyethylene diphosphonic acid(HEDP) - 45om plus g.In other words, 1 mg chelating agent can only chelate less than 0.5 mg CaCO3 scale.If calcium and magnesium ions with a total hardness of smm0FL need to be stabilized in the circulating water system, the required chelating agent is l000m/L, which is economically unbearable.It can be seen that the contribution of scale inhibitor chelation is only a small part.However, in medium and low hardness water, the chelation of scale inhibitor still plays an important role.
Dispersal action
The result of dispersion is to prevent the mutual contact and condensation of scaling particles, thus preventing the growth of scale.[1]Scaling particles can be calcium and magnesium ions, scaling particles composed of hundreds of CaCO3 and MgCO3 molecules, dust, sediment or other water insoluble substances.The dispersant has certainrelative molecular mass(or degree of polymerization), the dispersion performance is closely related to the size of the relative molecular weight (or degree of polymerization).If the polymerization degree is too low, the number of particles adsorbed and dispersed is small, and the dispersion efficiency is low;If the polymerization degree is too high, there will be too many particles adsorbed and dispersed, and the water will become turbid, even forming flocs (at this time, the effect is similar to that of flocculants).Compared with chelation, dispersion is efficient.The experiment shows that 1 mg dispersant can make 10-100 mg scale forming particles stably exist in circulating water. In medium and high hardness water, the dispersal function of scale inhibitor plays a major role.
Lattice distortion
When the hardness and alkalinity of the system are highchelator When dispersants are not enough to completely prevent their precipitation, they will inevitably precipitate.If there is no dispersant, the scale growth will follow the general law of crystal growth,[1]The scale formed is firmly attached to the surface of the heat exchanger.If there is enough dispersant, the scaling particles (composed of hundreds of CaCO3 molecules) will bedispersantAdsorption and enclosure prevent scaling particles from forming in its regular latticelatticeThe dirt generated is soft and easy to be washed away by water flow.
classification
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According to the polymerization composition of scale inhibitors, they can be divided into natural polymer scale inhibitors and synthetic polymer scale inhibitors. Synthetic polymer scale inhibitors can be further divided into carboxylic acid polymer scale inhibitors, sulfonic acid polymer scale inhibitors, phosphorus containing polymer scale inhibitors and environment-friendly scale inhibitors.[2]
Organic
Phosphine series scale inhibitor
ATMP has good chelation, low limit suppression and lattice distortion.It can prevent scaling salts from forming scale in water, especially calcium carbonate scale.ATMP has stable chemical properties in water and is not easy to hydrolyze.When the concentration in water is high, it has good corrosion inhibition effect.
HEDP is an organic phosphonic acidCorrosion inhibitor, can form stablecomplex compound, can dissolve oxides on metal surface.It can still play a good role of corrosion and scale inhibition at 250 ℃. It is still stable at high pH, difficult to hydrolyze, and difficult to decompose under general photothermal conditions.Acid and alkali resistance and chlorine oxidation resistance are better than other organic phosphonic acids (salts).
EDTMPS is a nitrogen containing organic polyphosphonic acid, which is a cathodic corrosion inhibitor. Compared with inorganic polyphosphates, its corrosion inhibition rate is 3-5 times higher.It is miscible with water, non-toxic and pollution-free,chemical stabilityIt has good temperature resistance and good scale inhibition effect at 100 ℃.EDTMPS can dissociate into 8 positive and negative ions in aqueous solution, so it can chelate with multiple metal ions to form multiple monomer structure macromolecular network complexes, which are loosely dispersed in water, so that the normal crystallization of calcium scale is destroyed.EDTMPS has good scale inhibition effect on calcium sulfate and barium sulfate scale.
EDTMPA has a strong ability to chelate metal ionscomplexationThe constant is the largest among all chelating agents including EDTA.EDTMPA isHigh purity reagentIt is non-toxic and can be used asSemiconductor chipThe cleaning agent of is used for manufacturing integrated circuits;It is used as a carrier of radioactive elements in the pharmaceutical industry to check and treat diseases;The chelating capacity of EDTMPA is far more than that of EDTA and DTPA, and EDTMPA can be used as a substitute in almost all places where EDTA is used as a chelating agent.
Organic phosphonate scale inhibitor
ATMP·Na4
It is a neutral sodium salt of ATMP, which can prevent scaling salts in water from forming scale, especially calcium carbonate scale.ATMP·Na4 is suitable for circulating cooling water and oilfield reinjection water system of thermal power plants and oil refineries.ATMP·Na4 also has good compatibility with other additives.ATMP·Na4 is especially suitable for neutral to acidic formula, without ammonia odor.
ATMP·Kx is part of the potassium salt solution of ATMP, relative to the equivalent amount of sodium salt,ATMP·Kx has higher solubility, which can prevent scaling salts from forming scale in water, especially calcium carbonate scale.ATMP·Kx is especially suitable for oilfield reinjection water system.
HEDP·Na4 is widely used in power, chemical, metallurgical, fertilizer and other industrial cyclescooling waterScale and corrosion inhibition of low-pressure boiler, oilfield water injection and oil pipeline.
Polycarboxylic acid scale inhibitor dispersant
PAAS is non-toxic, soluble in water, and can operate under alkaline and medium concentration times without scaling.PAAS can disperse microcrystals or sediment of calcium carbonate, calcium sulfate and other salts in water without precipitation, so as to achieve the purpose of scale inhibition.
AA/AMPS is acrylic acid and2-acrylamide-2-methylpropane sulfonic acid(AMPS).Because the molecular structure contains carboxylic acid group and strongly polar sulfonic acid group with good scale inhibition and dispersion performance, it can improve the calcium tolerance, have significant scale inhibition effect on calcium phosphate, calcium carbonate, zinc scale, etc. in water, and has excellent dispersion performance.It has obvious synergistic effect when mixed with organic phosphine.It is especially suitable for water with high pH, high alkalinity and high hardness, and is the most ideal for operation with high concentration timesScale inhibitor dispersantone of.Copolymer scale inhibitor asWater treatment chemicals It has many advantages, such as wide variety, mature synthesis method, wide range of applicable water quality, low toxicity and pollution-free. It is a kind of green scale inhibitor with great development prospects.[3]
PESA is a "green" environmental protection multi scale and corrosion inhibitor without phosphorus and nitrogen.PESA has good scale inhibition and dispersion performance for calcium carbonate, calcium sulfate, barium sulfate, calcium fluoride and silicon scale in water, and its scale inhibition effect is better than that of common organic phosphorus scale inhibitors.The combination of PESA and phosphonate has a good synergistic effect.At the same time, PESA has a certain corrosion inhibition effect and is a multiple scale inhibitor.It can form low phosphorus orPhosphorus free corrosion and scale inhibitorTherefore, it has a very broad application prospect.[3]
PASP isWater soluble polymerIt is a new type of green water treatment agent, which is phosphorus free, non-toxic, pollution-free and fully biodegradable.It has strong chelating ability for ions, and has dual effects of corrosion inhibition and scale inhibition. It has good scale inhibition effect on calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate and other scaling salts, and the scale inhibition rate of calcium carbonate can reach 80%.
Compound scale inhibitor
Special corrosion and scale inhibitor for boiler
It is a composite composed of organic phosphonic acid, polycarboxylic acid and other polymers. It has very high corrosion and scale inhibition performance, and its temperature resistance is particularly good. It can be effectively applied to the boiler water treatment of low-pressure boilers.
Special scale inhibitor for heat supply network
It is mainly composed of high efficiency dispersant, phenolic hydroxyl group, sulfonic acid group, etc., which has lattice distortion effect on scaling factors such as calcium carbonate and calcium sulfate in water, making scale not easy to be firmly adsorbed on the wall of the vessel, but loosely dispersed in water, showing excellent scale inhibition effect.
Corrosion and scale inhibitor
It is composed of organic phosphonic acid, polycarboxylic acid, carbon steel corrosion inhibitor, etc. It has good chelating and dispersing effect on calcium carbonate, calcium phosphate, etc. in water, and has good corrosion inhibition effect on carbon steel, mainly used in steel plantsCirculating cooling water systemIts corrosion and scale inhibition effect is good and its scale inhibition power is strong.
Corrosion and scale inhibitor
It is compounded of organic phosphonic acid, polycarboxylic acid, carbon steel corrosion inhibitor and copper corrosion inhibitor. It has good chelating and dispersing effect on calcium carbonate, calcium sulfate, calcium phosphate, etc. in water, and has good corrosion inhibition effect on carbon steel and copper.
This product is mainly composed of a variety of organic phosphonic carboxylic acids, polycarboxylic acids, sulfonate containing copolymersCorrosion inhibitor, special interfacial active agent, etc., applicable to the circulating cooling water system with high concentration ratio of 1500 ppm Ca2++alkalinity in the circulating water.
RO scale inhibitor
scale inhibitor The dispersant is a highly effective scale inhibitor and dispersant, especially suitable for reverse osmosis systems with high barium and strontium content in reverse osmosis feed water and serious scaling tendency of barium sulfate and strontium sulfate.It can effectively prevent scaling in a wide range of concentration of scaling substances.Reverse osmosis scale inhibitor is used in reverse osmosis system (RO), nanofiltration system (NF) or ultrafiltration system (UF).Reverse osmosis membraneScaling is the key factor restricting the popularization and application of RO in water treatment.Once the membrane system scales in a large area, cleaning the membrane and replacing the reverse osmosis membrane are the only solutions.[4]
BTA (Na) can be adsorbed on the metal surface to form a thin film to protect copper and other metals from the corrosion of atmosphere and harmful media;BTA (Na) can be used in circulating cooling water system with various scale inhibitorsBactericidal AlgicideWhen used together, the corrosion inhibition effect of the circulating cooling water system is good, and the dosage in the circulating water is 2-4mg/L.BTA (Na) can also be used as anti tarnish agent for copper and silver, automobile coolantLubricant additives。
Mercaptobenzothiazole sodium (MBT):
MBT (Na) can be used as copper corrosion inhibitor in circulating cooling water system.MBT (Na) corrosion inhibition mainly depends on a chemical adsorption with active copper atoms or copper ions on the surface of metal copper;Or chelation will occur to form a dense and firm protective film, so that copper equipment can be well protected, and the usage is generally 4mg/L,MBT (Na) can also be used as plasticizer, acid copper plating photometric agent, etc.
TTA can be used as a corrosion inhibitor for nonferrous copper and copper alloys, and also for ferrous metals.TTA adsorbs on the metal surface and forms a thin film to protect copper and other metals from the corrosion of harmful media in the atmosphere and water.Film of the this product is more uniform, and effect of the compound use with the mercaptobenzothiazole sodium is better.TTA is dissolved in alcohol or alkali and added to the circulating water. The concentration of this product in the water is 2-10mg/L. If the non-ferrous metals in the water system have been seriously corroded, this product can be added at 5-10 times the normal concentration to make the system passivate rapidly.
Concentrated scale inhibitor
Concentrated scale inhibitor is a compound formulation of scale inhibitor obtained by concentrating the above types of scale inhibitors through experimental analysis of enterprise operation.The characteristics of concentrated scale inhibitor are: 1. higher efficiency;2. More convenient to use;3. Smaller dosage;4. More economical;5. Manpower saving;6. Save storage space;7. More secure.
Scale inhibitor
Non phosphorus scale inhibitor
Phosphorus free scale inhibitor can be applied to different water sources. The product adopts phosphorus free polymer and dispersibilityPolymerTo prevent hardness and iron oxide deposition.It is a highly effective liquid scale inhibitor and dispersant, which can effectively control the scaling of calcium carbonate, calcium sulfate and strontium sulfate. The LSI of calcium carbonate is up to+3.0, but scaling will not occur.It can be used to control the scaling and sedimentation of membrane separation system and reduce the blockage of particles.
matters needing attention
non-toxicInhalation: transfer to fresh air. If shortness of breath, oxygen inhalation and symptoms continue to deteriorate, seek medical advice immediately.Skin contact: Take off contaminated clothes and shoes immediately and wash with plenty of water.Eye contact: wash with an eye washer for at least 15 minutes. If eye irritation persists or worsens, give medical care and take it offcontact lenses。Ingestion: Do not induce vomiting without doctor's advice.Do not feed the unconscious person. If necessary, send him to the doctor for treatment.
expectation
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According to the strategy of sustainable development, greening is undoubtedly the development direction of scale inhibitors in the 21st century.Therefore, the future work should focus on the three major goals of performance, economy and environment. On the basis of further improving the existing products and improving the quality, the mechanism research and compound research should be strengthened to reduce costs and pollution;Accelerate the research and application of platinum based and tungsten based water treatment agents with China's resource advantages;In terms of the synthesis of new products, it is necessary to break through the existing ideas and actively use green chemical technology. First, the target molecules should be greenized, and clean processes should be adopted to synthesize phosphorus free, nitrogen free, toxic free, biodegradable, and environmentally friendly efficient scale inhibitors to completely replace phosphorus containing formulations.[3]
