Scale inhibitors in Water Treatment Chemicals
Scale inhibitors are one of the important water treatment agents. At present, scale inhibitors are mainly used for scale inhibition and sustained release of circulating water. They are widely used for water treatment of boiler water, oil field water, etc.
The scale inhibitor is a kind of medicament which has a poorly soluble inorganic salt capable of dispersing in water, prevents or interferes with precipitation and scaling of a poorly soluble inorganic salt on a metal surface, and maintains a good heat transfer effect of a metal device.
Scale inhibitors not only control scale, but also control corrosion products, slime, and sludge to some extent. A large amount of scale-forming material can be controlled by adding a small amount of scale inhibitor.
Early use of scale inhibitors is processed natural polymer products such as starch, sodium gluconate, tannin, sulfonated lignin and the like. The natural scale inhibitor has the advantages of low price and no pollution, but its scale inhibition rate is low, so the dosage of the medicament is large.
In the 1960s, the company developed new scale inhibitors, which were synthetic or polymeric products, scale inhibitors, and higher scale inhibition rate than natural scale inhibitors, which can meet the requirements of higher scale inhibition.
It is generally believed that its scale inhibition mechanism is as follows.
Inorganic scale (such as calcium carbonate) crystals are arranged in a certain lattice when growing. The crystal is dense and relatively strong. When a polycarboxylic acid or an organophosphate (phosphonic acid or organophosphate) scale inhibitor is contained in water, the group of the scale inhibitor has a chelation ability to the metal ion. It interferes with the crystal of inorganic scale, causing the crystal lattice to be distorted and become an irregular crystal. This is the lattice distortion effect.
Lattice distortion causes a hard scale to become amorphous and soft. The crystal of the scale is not easy to grow, and there are a large number of voids in the scale layer, and the adhesion force to each other is poor, and it is easily washed away in the water flow and can be discharged together with the sewage.
ATMP is added to the circulating water because it has good miscibility, it can prevent the formation of scale in the scale, especially the formation of calcium carbonate scale.
ATMP acid is used in circulating water in thermal power plants and refineries to reduce corrosion and scaling of metal equipment or pipelines.
ATMP chemical is used as a metal ion chelating agent in the textile printing and dyeing industry. Prolonged exposure to air or water in metal equipment can cause some corrosion and scaling, and then the metal surface can be well treated by adding a certain amount of amino trimethylene phosphonic acid.
Scale inhibitors are important water treatment agents and one of the largest product categories in water treatments. Therefore, the water treatment agent cannot bypass the scale inhibitor.
The scale inhibitor is a kind of medicament which has a poorly soluble inorganic salt capable of dispersing in water, prevents or interferes with precipitation and scaling of a poorly soluble inorganic salt on a metal surface, and maintains a good heat transfer effect of a metal device.
Scale inhibitors not only control scale, but also control corrosion products, slime, and sludge to some extent. A large amount of scale-forming material can be controlled by adding a small amount of scale inhibitor.
Early use of scale inhibitors is processed natural polymer products such as starch, sodium gluconate, tannin, sulfonated lignin and the like. The natural scale inhibitor has the advantages of low price and no pollution, but its scale inhibition rate is low, so the dosage of the medicament is large.
In the 1960s, the company developed new scale inhibitors, which were synthetic or polymeric products, scale inhibitors, and higher scale inhibition rate than natural scale inhibitors, which can meet the requirements of higher scale inhibition.
It is generally believed that its scale inhibition mechanism is as follows.
Inorganic scale (such as calcium carbonate) crystals are arranged in a certain lattice when growing. The crystal is dense and relatively strong. When a polycarboxylic acid or an organophosphate (phosphonic acid or organophosphate) scale inhibitor is contained in water, the group of the scale inhibitor has a chelation ability to the metal ion. It interferes with the crystal of inorganic scale, causing the crystal lattice to be distorted and become an irregular crystal. This is the lattice distortion effect.
Lattice distortion causes a hard scale to become amorphous and soft. The crystal of the scale is not easy to grow, and there are a large number of voids in the scale layer, and the adhesion force to each other is poor, and it is easily washed away in the water flow and can be discharged together with the sewage.
ATMP is added to the circulating water because it has good miscibility, it can prevent the formation of scale in the scale, especially the formation of calcium carbonate scale.
ATMP acid is used in circulating water in thermal power plants and refineries to reduce corrosion and scaling of metal equipment or pipelines.
ATMP chemical is used as a metal ion chelating agent in the textile printing and dyeing industry. Prolonged exposure to air or water in metal equipment can cause some corrosion and scaling, and then the metal surface can be well treated by adding a certain amount of amino trimethylene phosphonic acid.
Polymeric scale inhibitors are widely used in the oil and gas field because of their enhanced thermal stability and better environmental compatibility. However, the squeeze efficiency of such threshold inhibitors, not only polymeric scale inhibitors but also phosphonates, is typically poor in conventional squeeze treatment.
ReplyDeleteNanoparticle-crosslinked polymeric scale inhibitors were developed for scale control [98]. Nearly monodisperse boehmite nanoparticles with an average size of 2.8 nm were synthesized and used to crosslink sulfonated poly(carboxylic acid). Crosslinked AlO(OH) containing nanoinhibitors were produced to increase the retention of the sulfonated poly(carboxylic acid) in formations by converting liquid-phase polymeric scale inhibitors into a viscous gel.
Conventional polymer and phosphonate scale inhibitors may not be appropriate for the application in high-pressure and high-temperature reservoirs. Only a limited range of commercially available oil field scale inhibitor chemicals are sufficiently thermally stable at temperatures above 150 °C.
These chemicals are homopolymers of vinylsulfonate and copolymers of acrylic acid (AA) and vinylsulfonate. Other polymers, such as poly(maleic acid), poly(itaconic acid), and maleic acid/AA copolymers, may offer similar thermal stability (Collins, 1995). Thermal stability tests, influence on pH, ionic strength, and oxygen on conventional polymer and phosphonate scale inhibitors, for example, on phosphinopolycarboxylate, PVS, pentaphosphonate, and hexaphosphonate, have been presented (Graham et al., 1997, 1998b, 1998a; Dyer et al., 1999).
As pointed out above, it has been commonly believed that phosphonate scale inhibitors may not work for high-temperature inhibition applications, it has been more recently shown that phosphonate inhibitors are somehow effective at 200 °C under strictly anoxic conditions and in NaCl brines (Fan et al., 2010). In contrast, phosphonate inhibitors may precipitate with Ca2+ ions in a brine at high temperatures.