A kind of protective coating for anode plates of sintering electrostatic precipitator system

Abstract

The invention discloses a protective coating for anode plates of a sintered electrostatic precipitator system, which belongs to the technical field of metal corrosion protection. The protective coating is composed of a binder, a filler and an auxiliary agent; wherein the binder is a lithium silicate aqueous solution; the filler is copper powder, and the mass ratio of the filler to the binder is 1.5-2:1; the auxiliary agent is composed of an anti-settling aid and a conductive aid, the anti-settling aid is fumed silica and talcum powder, and the amount of fumed silica added is 2.5%-3% of the mass of the binder; the amount of talcum powder added is 1.2%-2% of the mass of the binder; the amount of conductive additive added is 3%-7% of the mass of the binder. The protective coating can form a protective coating with good anti-corrosion performance, heat resistance and conductivity on the surface of the anode plate; the coating does not contain organic solvents, heavy metals, free acids and other harmful substances, and has significant safety and environmental protection characteristics; it can effectively extend the service life of the sintered electrostatic precipitator anode plate.

Description

Technical Field

[0001] The invention belongs to the technical field of metal corrosion protection, and in particular relates to a protective coating for anode plates of a sintering electrostatic precipitator system. Background Art

[0002] Sintering electrostatic precipitator is an important environmental protection equipment for steel enterprises. The internal corrosion environment of the sintering electrostatic precipitator system is harsh and complex, mainly manifested in: high chloride content, acid gas condensation, high and low temperature alternation, flue gas particle abrasion, electric field effect, etc. The anode plate is the main component of the electrostatic precipitator system, and its function is to collect flue dust particles. The steel consumption of the anode plate is usually 40%~50% of the total steel consumption of the electrostatic precipitator system. Under the coupling effect of the above-mentioned multiple corrosion factors, the service life of the anode plate of the electrostatic precipitator system is short, and the corrosion of the anode plate has become a serious problem faced by the electrostatic precipitator system during operation.

[0003] Some research has been carried out in China around the problem of corrosion protection of components of electrostatic precipitator systems. For example, the patent with publication number CN105536993A provides a preparation method for modifying the surface of carbon steel anode plates by gluing glass fibers with epoxy resin layers. The method applies epoxy resin with a temperature resistance of more than 110°C and acid corrosion resistance to the anode plates, applies multiple layers of epoxy resin layers on the surface of the anode plates, eliminates bubbles inside the coating by rolling defoaming, adheres low-density glass fiber cloth, and presses the bottom layer of the glass fiber cloth into the upper layer of the epoxy resin that has not been completely cured. It can form a The surface liquid film formed is uniform and stable, which can effectively prevent dust accumulation and scaling on the electrode plates, thereby ensuring the long-term efficient and stable operation of the wet electrostatic precipitator; however, the flue gas temperature inside the sintering electrostatic precipitator system is usually above 120°C and contains a large amount of SO2, so the temperature resistance and anti-aging properties of the coating layer described in the patent are difficult to meet the corrosion protection requirements of the sintering electrostatic precipitator system; in addition, the cobalt isooctanoate used in the preparation process of the coating layer is carcinogenic and skin irritating, and methyl ethyl ketone peroxide is flammable and skin irritating; this method requires a total of three layers of epoxy resin to be coated, and the coating time interval between each two layers is more than 16 hours. The epoxy resin layer needs to be placed for 3 to 5 days after adhering to the glass fiber cloth. Therefore, the preparation efficiency of the coating layer is not high. Patent CN103421398A discloses a self-cleaning electrostatic precipitator and electrostatic precipitator plate surface coating, which is composed of water-based acrylic resin, diethylene glycol butyl ether, wetting agent, leveling agent, water-based amino resin and highly conductive graphite powder, which can effectively solve the problem of oil adhesion; but its heat resistance is difficult to meet the use requirements of sintering electrostatic precipitator system. Patent CN1125754A discloses a conductive anti-rust, anti-corrosion and heat-resistant coating and its preparation method and use. The coating is mainly made of graphite, synthetic resin varnish, silicone oil and metal oxide fillers and solvents; the coating has good conductive, anti-rust, anti-corrosion and heat-resistant properties, and can withstand the harsh environment of high temperature and high humidity of 350°C; but it contains lead tetroxide and organic solvents, which is difficult to promote and use under increasingly stringent environmental protection requirements. Patent CN1775879A discloses a flue gas purification anti-corrosion conductive coating composed of vinyl ester resin, conductive particles, peroxide curing agent, accelerator, styrene, etc. It is suitable for corrosion protection of electron beam irradiation and pulse corona discharge desulfurization and denitrification devices, wet electrostatic precipitators, ultra-low temperature electrostatic precipitators and other corona discharge flue gas purification equipment. It can also be used for corrosion protection of low resistivity dust electrostatic precipitators and general flue gas purification equipment that does not require conductivity. However, the coating contains organic solvents and also does not meet the increasingly stringent environmental protection requirements. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention provides an anode plate protective coating suitable for sintering electrostatic precipitator systems in the steel production field through process means such as selection of protective coating components and optimization of ratios, and obtains good comprehensive performance.

[0005] In order to achieve the above-mentioned invention object, the present invention provides a protective coating for anode plates of a sintering electrostatic precipitator system, wherein the protective coating is composed of a binder, a filler and an additive;

[0006] Wherein, the binder is a lithium silicate aqueous solution;

[0007] The filler is copper powder, and the mass ratio of the filler to the binder is 1.5-2:1;

[0008] The additives are composed of an anti-settling additive and a conductive additive. The anti-settling additive is composed of fumed silica and talcum powder. The amount of fumed silica added is 2.5% to 3% of the mass of the binder; the amount of talcum powder added is 1.2% to 2% of the mass of the binder; and the amount of the conductive additive added is 3% to 7% of the mass of the binder.

[0009] In the above technical solution, further, the modulus of the lithium silicate is 6.5-9, and the mass concentration of the lithium silicate aqueous solution is 15%-21%.

[0010] Among the above protective coating components, lithium silicate in the binder is one of the main film-forming substances of the coating. The Si-O bond of lithium silicate reacts with fillers and iron elements on the surface of steel to form silicate polymers; lithium silicate can absorb moisture and carbon dioxide in the air and continue to react to form a network of insoluble products, which provide cohesion for the coating and make the coating tightly adhere to the surface of the steel substrate.

[0011] Furthermore, the average particle size of the copper powder is 18 μm to 38 μm;

[0012] The filler is copper powder. After the coating is cured into a film, the copper powder particles form a conductive network, making the coating conductive; its addition amount and particle size have a significant impact on the coating performance.

[0013] Furthermore, the average particle size of the fumed silica is 7 nm to 15 nm, and the average particle size of the talc is 2.3 μm to 5.7 μm.

[0014] The anti-settling additives in the additives are fumed silica and talcum powder. In the coating, copper powder particles are prone to sedimentation due to the large density difference between copper powder and binder. The addition of fumed silica makes the coating thixotropic, and the viscosity of the coating is relatively high when it is still, making it difficult for copper powder particles to settle. When the coating is stirred, its viscosity decreases as the shear stress increases, which is beneficial to the coating construction. Talc also plays a role in adjusting the viscosity of the coating to prevent the copper powder particles from settling, and also has the function of improving the conductivity of the coating.

[0015] Furthermore, the conductive additive is one of lithium trifluoromethanesulfonate, lithium tetrafluoroborate and sodium tetrafluoroborate. The three salts of lithium trifluoromethanesulfonate, lithium tetrafluoroborate and sodium tetrafluoroborate have good conductivity and good thermal stability, and can improve the corrosion protection performance of the coating on the plate.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The protective coating for anode plates of a sintered electrostatic precipitator system of the present invention can form a protective coating with good anti-corrosion, heat resistance and electrical conductivity on the surface of the anode plates; the coating does not contain any organic solvents, heavy metals, free acids or other harmful substances, and has significant safety and environmental protection characteristics; it can effectively extend the service life of anode plates of sintered electrostatic precipitators. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundancy, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified. The acetic acid salt spray test is carried out in accordance with GB / T 10125-2021; the heat resistance evaluation is carried out in accordance with GB / T 1735-2009, with a test temperature of 200°C and a holding time of 144 h.

[0019] A protective coating for anode plates of a sintering electrostatic precipitator system, the protective coating comprising a binder, a filler and an additive;

[0020] Wherein, the binder is a lithium silicate aqueous solution; the modulus of the lithium silicate is 6.5-9, and the mass concentration of the lithium silicate aqueous solution is 15%-21%.

[0021] The filler is copper powder, and the mass ratio of the filler copper powder to the binder is 1.5-2:1; the average particle size of the copper powder is 18 μm-38 μm.

[0022] The additives are composed of an anti-settling aid and a conductive aid. The anti-settling aid is composed of fumed silica and talc. The amount of fumed silica added is 2.5% to 3% of the mass of the binder; the amount of talc added is 1.2% to 2% of the mass of the binder; and the amount of conductive aid added is 3% to 7% of the mass of the binder. The average particle size of the fumed silica is 7 nm to 15 nm, and the average particle size of the talc is 2.3 μm to 5.7 μm. The conductive aid is one of lithium trifluoromethanesulfonate, lithium tetrafluoroborate, and sodium tetrafluoroborate.

[0023] The matters not described in the following embodiments are the same as the description of the above specific implementation methods.

[0024] Example

[0025] A protective coating for anode plates of a sintered electrostatic precipitator system, the specific composition ratios of the embodiments and comparative examples are shown in Table 1.

[0026] Table 1 Component ratios of coatings in the examples and comparative examples

[0027]

[0028] According to the composition ratios of the coatings of Examples 1-6 and Comparative Examples 1-6, the mass contents of the main components of each Example and Comparative Example were calculated, as shown in Table 2.

[0029]

[0030] The preparation of the coatings of the embodiment and comparative example follows the preparation process of general inorganic water-based coatings, and the process methods are all conventional technologies in the field; the anode plate protective coatings prepared in the embodiment and comparative example are tested by application experiments, and the materials used in the experiment are ST12 cold-rolled plain carbon steel plates, which are common materials for sintered electrostatic precipitator anode plates. The specific application effects of the coatings of the embodiment and comparative example are shown in Table 3.

[0031]

[0032] It can be seen from the specific application effects of the coatings in each embodiment and comparative example that the material of the sintered electrostatic precipitator anode plate coated with the coating described in the technical solution of the present invention has a lower surface resistance. The amount of lithium silicate contained in the binder in Comparative Example 1 is too low, and there are many defects inside the coating after curing, and the protectiveness is poor; the modulus of lithium silicate in Comparative Example 2 is too high, and the coating has poor adhesion to the base after curing, resulting in poor protectiveness; the amount of copper powder added in Comparative Example 3 is too low, so the coating conductivity is not as good as that of Examples 1 to 6; the average particle size of the copper powder in Comparative Example 4 is too large, which makes the copper powder easy to settle, resulting in poor adhesion of the coating and increased surface resistance; the content of fumed silica and talcum powder in Comparative Example 5 is too low, and the resulting copper powder particle sedimentation leads to poor adhesion of the coating and increased surface resistance; the amount of conductive additive added in Comparative Example 6 is too low, so the coating conductivity is not as good as that of Examples 1 to 6.

[0033] The technical solution of the present invention combines an inorganic silicate self-curing coating system with an inorganic-organic composite conductive filler system, overcoming the shortcomings of the prior art, such as containing organic solvents and harmful components, complicated construction process, and poor heat resistance. A protective coating with good anti-corrosion, heat resistance, and conductivity can be formed on the surface of the anode plate; it can effectively extend the service life of the sintered electrostatic precipitator anode plate.

[0034] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A protective coating for anode plates of a sintering electrostatic precipitator system, characterized in that: The protective coating is composed of a binder, a filler and an additive; Wherein, the binder is a lithium silicate aqueous solution; the modulus of the lithium silicate is 6.5-9, and the mass concentration of the lithium silicate aqueous solution is 15%-21%; The filler is copper powder, and the mass ratio of the filler to the binder is 1.5-2:1; The auxiliary agent is composed of an anti-settling auxiliary agent and a conductive auxiliary agent. The anti-settling auxiliary agent is composed of fumed silica and talcum powder. The conductive auxiliary agent is one of lithium trifluoromethanesulfonate, lithium tetrafluoroborate and sodium tetrafluoroborate.

2. The protective coating for anode plates of sintering electrostatic precipitator system according to claim 1 is characterized in that: The average particle size of the copper powder is 18 μm to 38 μm.

3. The protective coating for anode plates of sintering electrostatic precipitator system according to claim 1, characterized in that: The amount of the fumed silica added is 2.5% to 3% of the mass of the binder; the amount of the talc added is 1.2% to 2% of the mass of the binder.

4. The anode plate protective coating for sintering electrostatic precipitator system according to claim 1, characterized in that: The average particle size of the fumed silica is 7 nm to 15 nm, and the average particle size of the talc is 2.3 μm to 5.7 μm.

5. The protective coating for anode plates of sintering electrostatic precipitator system according to claim 1, characterized in that: The conductive additive is added in an amount of 3% to 7% of the binder mass.

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