Introduce a production method of boiler anti-corrosion and anti-wear spraying technology

       Boiler furnace spraying, thermal spraying, boiler anti-wear spraying, boiler anti-corrosion spraying, supersonic arc spraying, boiler heating surface anti-wear and anti-corrosion spraying, boiler water wall anti-wear spraying, deflector anti-wear, anti-wear plate installation, boiler deflector Installation, latitude and longitude anti-wear

【Background technique】

Due to the characteristics such as furnace type structure and design parameters, the circulating fluidized bed boiler, the heating surface parts such as the water wall of its furnace, has extremely bad operating conditions, and suffers from high-speed, high-temperature, high-concentration bed material and fuel flue gas for a long time. Uniform erosion wear and corrosion, especially in the unburned zone in the combustion chamber with water wall heating surface and other local areas, there are eddy current effects and cutting effects that cause serious wear, and the corrosion and thinning of the pipe wall is serious, which is very easy to cause leakage and pipe burst.

Because its coal-fired sulfur content is large, soot blower area water-cooled wall, burner area water-cooled wall, low over, high again, economizer, cladding wall, high over and other area local heating surfaces suffer from high temperature, sulfur corrosion The wear and tear of dust particles is particularly serious, resulting in serious pipe bursting and pipe replacement, and heavy losses. At the same time, a large amount of ash powder produced by coal combustion, in the complex dynamic process of the internal combustion of the boiler, violently hits the water-cooled wall, causing serious cutting of the working surface of the water-cooling wall, so that the working surface of the water-cooling wall tube is worn into small platforms of different degrees. The actual thinning of the wall thickness of the water-cooled wall will easily lead to the tube burst due to insufficient strength of the water-cooled wall tube at high temperature, and its harmful effect is as serious as high-temperature corrosion. During the operation of the boiler, the furnace temperature can be as high as thousands of degrees. Due to the existence of sulfur and other harmful impurities in the burning coal, the water wall is generally subject to high temperature corrosion. The hazards involved in high temperature corrosion include S02, SO3, H2S, HCl, alkali metal salts and vanadium salts produced during the combustion process. Among them, sulfide is the main factor of high temperature corrosion of boilers. One is the corrosion caused by the action of hydrogen sulfide in the flue gas and the metal of the pipe wall. Sulfur-containing compounds produce monoatomic sulfur at high temperature of the metal, and sulfur reacts with iron in the pipeline to form sulfide. Iron (Fe+S—FeS); the second is that sulfate is formed by incombustible sulfur under the action of high temperature, mixed with ash and deposited on the surface of the pipe wall, but it no longer has various good high-temperature mechanical properties required by water-cooled wall pipes. As a result, the effective wall thickness of the water-cooled wall tube is reduced, so that its effective bearing capacity is continuously reduced, thereby forming corrosion. In addition, the high temperature flue gas can impact the pipe wall at a speed of more than 8 m/s, and the corrosion of the flue gas and the scouring of the ash particles alternate on the metal surface, resulting in the thinning of the pipe wall.

[0004] Secondly, it is also susceptible to high temperature oxidation and thermal corrosion of sulfate and sulfur and sulfide. The water-cooled wall tube has high temperature oxidation and high temperature corrosion conditions, and its flue gas temperature is high, and it is oxygen-enriched combustion. Practice has proved that, above 300 ° C, when the high temperature of the tube surface is increased by 50 ° C, the corrosion rate increases by 1 times. During the operation of the boiler, the surface of the heating surface tube is oxidized at high temperature first, and Fe2O3 is formed on the surface. Secondly, Na2O and K2O in the fuel ash combine with SO3 in the flue gas to form sulfate, which captures the fly ash to form slagging and sulfur slag. In the flue gas, 503 and M 2S04 react with Fe 203 on the pipe wall to form composite sulfate MFe(S0 4) 2 or M3Fe(SO4) 3, which is decomposed into loose iron oxide and sulfate deposits by high temperature. , which is easily taken away by the flow of fly ash, and the oxidation corrosion continues to the depth of the tube wall; in addition, the sulfur content in the fuel, which is burned to generate S and HS, also produces strong corrosion on the tube wall, and reacts with Fe to form FeS.

Under the combined action of above-mentioned multiple factors, these heating surface parts are constantly scoured, worn, oxidized, and corroded from outside to inside, making it gradually thinner, and when local can not bear the water vapor pressure in the pipe and cause explosion and loss.



[Content of the invention]



[0006] The present invention provides a boiler anti-corrosion and anti-wear spraying method in order to solve the problem that the water wall surface in the boiler existing in the prior art is easily corroded.

The present invention is realized by following technical scheme: a kind of new technology of boiler anti-corrosion and anti-wear spraying, concrete operation steps are as follows:

(1) Preparation before spraying: set up scaffolding as needed, remove sundries on the heating surface, inspect the quality of the sprayed parts of the pipe wall, put in place construction equipment, electrical wiring, air source pipeline connection, and laying of abrasive recycling canvas;

(2) Pretreatment of sprayed surface: According to the "General Rules for Surface Pretreatment of Thermal Sprayed Metal Parts", the non-effective surface, that is, the surface that is not sprayed, is shielded and protected by masking tape, hardwood or rubber cover, and the transition area is reserved; press The national standard is to use super quartz sand or brown corundum with firm and irregular edges and corners for surface treatment, and then use corundum sand for secondary sand blowing on the surface, use TR100 pocket surface roughness tester for testing, and then use clean kraft paper or plastic film. cover protection;

(3) spraying: adopt supersonic arc spraying equipment to carry out arc spraying according to GB11375-99 "Thermal Spraying Operation Safety", select iron-based self-adhesive gold wire material for priming spraying, thickness is more than 0.05 mm; Then adopt LX88A superhard wear-resistant Alloy wire or 45CT nickel-chromium-titanium alloy wire is sprayed, and the coating thickness is 0.5-0.6mm; the well-shaped spraying method is used, layered and partitioned, and every 5-6 ITl2 local area is sprayed to reach the thickness and then replaced. to other areas;

(4) Seal the surface of the metal thermal spray coating with LG-3 special sealing agent for high temperature wear and corrosion resistance.

In step (2), adopt pressure type high-efficiency sandblasting equipment to carry out sandblasting, utilize on-site air source or self-provided air compressor, exhaust flow≤6m /min, working pressure 0.55-0.8Mp; Sandblasting operation method is : A. First remove rust from bottom to top, grind the uneven heating surface to be smooth and then blast it immediately; B. Use quartz sand to remove rust, oxide scale and coking attachments on the steel surface, and reveal gray-white metallic luster: sandblasting The distance is 150-300mm, the sandblasting angle formed with the substrate is 50-90°, and each sandblasting is 5-6 m2; C. The surface of the substrate is roughened by spraying brown corundum, and the surface cleanliness reaches Sa3.0 level; after sandblasting The surface of the pipe wall is dry, free of dust, oil, scale, rust and other debris, the surface of the substrate presents a homogeneous metallic luster, the cleanliness reaches Sa3.0 level, and the roughness reaches Rz80-120 μm; D. After sandblasting, use the TR100 pocket surface roughness tester to test the pretreated surface. If rust or unqualified parts are found to be reprocessed, the DC-2000B intelligent ultrasonic thickness gauge is used to test the pipe wall for the first time. Thickness measurement; arc spraying within 2 to 4 hours after sandblasting is completed.

Described in the step (2), the special grade quartz sand or brown corundum are screened before use, and the content of clay and fine dust in the sand is (5%, without oil; before sandblasting, the quartz sand is air-dried, and the water content≤1%, used The sand is clean and dry, and the sandblasting area is equipped with enclosures and other recycling measures to prevent moisture, rain, and impurities mixed into the sand, and do not pollute the surrounding environment.

Spraying equipment described in step (3) is ZPG-500A type supersonic arc spraying special-purpose spraying power supply and matching wire feeder; /s, coating porosity≤0.9%; Spraying process parameter is: arc voltage: 32-34V; Arc current: 160-200A; Atomizing air pressure: 0.5-0.8Mpa; Spraying distance: 100-150mm; The spraying is carried out cyclically every 5_6 Hl2 interval, the width of the spraying transition area is 100mm, the edge transitions smoothly, and there are no uneven steps. In step (3), the diameter of the LX88A superhard wear-resistant alloy wire or the 45CT nickel-chromium-titanium alloy wire is Φ2.0mm.

During described spraying operation, interlayer temperature≤80 ℃; First test spray on test plate before spraying, regulate voltage, electric current, wire feeding speed, compressed air flow, check the union and the hose joint of air circuit , no air leakage.

The present invention adopts LX88A wire material spraying boiler, and the technological operation is convenient, can effectively solve the problem that boiler is easy to produce corrosion in actual operation, under high temperature ceramics, makes whole coating more dense, reaches closed capillary effect, work High efficiency, material saving, no pollution, low energy consumption; reduce boiler maintenance costs. The coating formed by it will not cause damage to the heated surface, the wear-resistant spray layer is firmly combined with the base material, the joint surface is smooth, the transition surface is smooth, and there is no concave and convex platform, no peeling and cracking phenomenon, corrosion resistance, excellent High wear resistance, stability, corrosion resistance, hard cracking resistance, its anti-corrosion life can be extended to more than one year, to ensure that the boiler life is extended for more than one year.

【Detailed ways】

A kind of new technology of boiler anti-corrosion and anti-wear spraying, concrete operation steps are as follows:

(1) Preparation before spraying: Set up scaffolding as needed, remove large pieces of coke, debris, etc. on the heating surface, conduct a comprehensive quality inspection of the sprayed parts of the pipe wall, and use the existing conditions on site to carry out on-site construction equipment in place, electrical wiring , Air source pipeline connection, abrasive recycling canvas laying;

(2) Pretreatment of sprayed surface: According to the "General Rules for Surface Pretreatment of Thermal Sprayed Metal Parts", use masking tape, hardwood or rubber to shield and protect the non-effective surface, and reserve a transition area to ensure smooth edges of the coating Transition; according to the national standard, use super quartz sand or brown corundum with firm quality and irregular edges and corners for surface treatment, and screen the super quartz sand or brown corundum before use, the content of clay and fine dust in the sand is less than 5%, and there is no oil pollution; sandblasting The former quartz sand is air-dried with a moisture content (1%), and stored dry to prevent moisture, rain, and impurities mixed into the sand; the sand used is clean and dry, and the sandblasting area is provided with enclosures and other recycling measures to ensure that it does not pollute the surrounding environment. Sand blasting can be carried out after inspection and confirmation by the quality engineer. The surface is blown with corundum sand for the second time, and the TR100 pocket surface roughness tester is used for testing, and then covered with clean kraft paper or plastic film for protection.

Adopt pressure type high-efficiency sandblasting equipment to carry out sandblasting, utilize on-site air source or self-provided air compressor, exhaust flow≤6m/min, working pressure 0.55-0.8Mp; Sandblasting operation method is: A. first from Remove rust from bottom to top, polish the uneven heating surface smooth and then blast it immediately; B. Use quartz sand to remove rust, oxide scale, and coking attachments on the steel surface, and expose gray-white metallic luster: the blasting distance is 150-300mm, The sandblasting angle formed with the substrate is 50-90°, and each sandblasting is 5-6 m2; C. The surface of the substrate is roughened by spraying brown corundum, and the surface cleanliness reaches Sa3.0 level, which will not cause any damage to the thickness of the pipe wall. For damage, use the roughness sample block to control the inspection. After sandblasting, the surface of the pipe wall is dry, free of dust, oil, scale, rust and other debris. The surface of the substrate presents a homogeneous metallic luster, and the cleanliness reaches Sa3. Grade 0, the roughness reaches Rz80-120 ym; D. After sandblasting, the pretreated surface should be checked, and the pretreated surface should be tested with a TR100 pocket surface roughness tester. If rust or unqualified parts are found to be reprocessed, After passing the qualification, use DC-2000B intelligent ultrasonic thickness gauge to measure the thickness of the pipe wall for the first time; Maintain a high degree of activation of the sprayed surface.

(3) spraying: before spraying, when needing to stay in the middle between surface pretreatment and spraying operation, should adopt clean kraft paper or plastic film etc. to cover and protect the effective surface through pretreatment. According to GB11375-99 "Thermal Spraying Operation Safety", supersonic arc spraying is used, and LX73 iron-based self-adhesive gold wire is used for primer spraying, and the thickness is more than 0.05 mm; then LX88A superhard wear-resistant alloy wire of Φ2.0mm is used. , 45CT nickel-chromium-titanium alloy wire is sprayed, and the thickness of the coating is 0.5-0.6mm; the well-shaped spraying method is used, layered and partitioned, and every 5_6 Hl2 local area is sprayed to the thickness and then transferred to other areas to ensure that The bonding force and thickness of the sprayed layer are uniform to prevent leakage of spray;

Described spraying equipment is ZPG-500A type supersonic electric arc spraying special-purpose spraying power supply and matching wire feeder; Spray gun selects supersonic electric arc spray gun for use, and atomization airflow velocity＞500m/s, particle velocity is more than 420m/s, coating The porosity is less than 0.9%; the bonding strength between the coating and the substrate has also been significantly improved, and the spraying process parameters are: arc voltage: 32-34V; arc current: 160-200A; atomizing air pressure: 0.5-0.8Mpa; Spraying distance: 100-150mm; sandblasting and spraying are carried out every 5-6 m2 interval, the width of the spraying transition area is 100mm, the edge transitions smoothly, and there are no uneven steps.

(4) after spraying is finished, carry out coating quality inspection, and measure thickness more than 0.5-0.6mm to judge qualified, can enter next operation, otherwise should carry out supplementary spraying to unqualified position; Then use LG-3 type high temperature The special sealing agent for wear and corrosion resistance seals the surface of the metal thermal spray coating.

Operation precautions:

A. Working in blocks, the local area is sprayed to the design thickness and then transferred to other areas, and identification marks are set at the overlapping parts; during operation, the temperature between layers should not be higher than 80°C.

[0019] The wire feeding reel and the wire feeding situation are set up to be monitored by a special person to ensure smooth wire feeding, to prevent the wire from being "knotted", and at the same time, absolute insulation between the two wires must be guaranteed to avoid short circuit.

[0020] Before spraying, should be sprayed on the test plate, so as to adjust the voltage, current, wire feeding speed, compressed air flow, check the union and hose joints of the gas path, and there must be no air leakage. If it is found that the wire feeding is unstable, the arc is unstable and the combustion is unstable, and the air leakage is serious, it should be checked and adjusted in time. When adjusting the voltage, the main circuit should be disconnected to avoid damage to the main spraying power supply. The contact tips burned during the spraying process should be replaced in time, and the use of contact tips with excessive machining accuracy is prohibited.

In the spraying process, if it is found that the wire feeding is unstable, the fuse is broken, and the electric arc is intermittent phenomenon, the use condition of the contact tip should be checked first, and the installation of the wire guide tube should be checked again whether it is firm, and should be tightened in time when loosening.

【Sovereign item】

1. a new process for anti-corrosion and anti-wear spraying of boilers, it is characterized in that: concrete operation steps are as follows: (1) preparation before spraying: set up scaffolding as needed, remove the sundries on the heating surface, inspect the quality of pipe wall spraying parts, on-site Installation of construction equipment, electrical wiring, connection of air source pipelines, abrasive recovery, and canvas laying; (2) Pretreatment of sprayed surfaces: Carry out in accordance with the "General Rules for Surface Pretreatment of Thermally Sprayed Metal Parts", and use shielding for non-effective surfaces, that is, surfaces that are not sprayed Belts, hardwood boards or rubber shelters are used for shielding and protection, and transition areas are reserved; according to national standards, super-quality quartz sand or brown corundum with firm and irregular edges and corners is used for surface treatment, and corundum sand is used for surface secondary sand blowing. Use TR100 pocket surface roughness tester for detection, then use clean kraft paper or plastic film to cover and protect; (3) Spraying: according to GB11375-99 "Thermal Spraying Operation Safety", use supersonic arc spraying equipment to carry out arc spraying, select