Application of Thermal Spray Technology in Petrochemical Industry
According to the survey, the direct corrosion and wear caused by abrasion and corrosion in China's oil and petrochemical industry each year are serious problems that endanger the production of petroleum and petrochemical industries, and the economic losses have reached several hundred million RMB Yuan. Chinese oil industry pipelines, storage tanks, casing and other facilities corrosion and wear, with the development of China's oil and gas fields and equipment service life of more and more serious growth; and China's petrochemical industry, with the import of high-sulfur Crude oil refining, equipment corrosion is also increasingly serious. Therefore, due to corrosion and wear on the safe and stable operation of equipment adverse effects will become more prominent, there is an urgent need to improve the petrochemical industry mining and processing equipment, wear resistance and corrosion resistance.
Research on wear and corrosion of parts caused by corrosion shows that most of these failures occur on the surface of the material 3-4. The use of surface engineering techniques to deal with the surface of the material to improve the surface properties of materials, will effectively extend the service life of parts, therefore, surface engineering in the oil and petrochemical industry has an important position.
It refers to maintaining the original performance of the parts of the body material on the basis of its surface thermal spraying technology is an important surface treatment technology in surface engineering,
Surface prepared with a layer of superior performance of the coating, giving parts surface wear, corrosion resistance, high temperature, anti-oxidation, anti-fatigue and other properties. The biggest advantage of using thermal spray technology is the ability to produce surface functional thin layers superior to bulk material properties in a variety of ways, at a thickness just a few tenths of the size of the structure, leaving the part to have a higher Wear resistance, corrosion resistance and high temperature performance. Even using expensive, rare elements of superior performance does not add significant cost. In addition, the thermal spraying technology can also directly target the failure of many precious components, and implement the local surface strengthening, repairing and pre-protecting in order to prolong the service life or restore the use value. Therefore, the use of thermal spraying technology, economic and social benefits are enormous.
Second, the characteristics of thermal spraying technology and its commonly used methods
Thermal spraying technology is through a flame, arc or plasma and other heat sources, a wire or powder material heated to a molten or semi-molten state, and accelerate the formation of high-speed droplets, sprayed onto the substrate, the coating layer formed thereon. This coating is called a spray coating.
Compared with other surface coating technology, thermal spraying technology has the following characteristics:
1. A variety of ways. Thermal spray method up to a dozen, for the preparation of coating provides a variety of means
2. Coating the substrate material is not limited. Thermal spray coating can be prepared on almost all solid surfaces, such as metal materials, inorganic materials (glass, ceramics) and organic materials (wood, cloth, paper) and so on.
3. A wide range of spray material selection. Almost all of the metal, alloy, ceramic, plastic, etc. can be used as spraying material.
4. The size, size and shape of objects to be painted are not limited. Large-scale equipment can be large-scale spraying, but also part of the workpiece spraying. Spraying parts can be sprayed on the finished structure.
5. Can give ordinary materials with special surface properties. Materials can meet the wear, corrosion, high temperature oxidation, heat insulation, sealing and other special performance requirements, to save valuable materials, improve product quality, to meet a variety of engineering and cutting-edge technology needs.
6. Coating thickness easier to control. Thin people can be tens of microns, thick for a few millimeters.
7. Low cost, Remarkable economic benefits.
Thus, thermal spraying technology has the characteristics of flexible technology, strong applicability, easy to popularize, economic and other processes can not be replaced, occupy an important position in surface engineering.
At present, the most widely used methods in production practice are flame spraying (including wire flame spraying, powder flame spraying, explosion spraying, supersonic flame spraying), plasma spraying and arc spraying.
Third, the thermal spraying technology in the petroleum and petrochemical industry in the application status
1. Repair oil machinery
With the continuous development of advanced manufacturing technology and equipment engineering, manufacturing and maintenance will become more and more unified. "Maintenance" has been given a broader meaning. In 1984 the United States, "Technical Review" to promote renovation or regeneration of old products, and called "re-manufacturing." The energy required for remanufacturing is about 20% to 60% of the new products manufactured, and the price is only 40% -60% of the new products. Many of the old parts that are treated with thermal spray technology perform better than new ones. Oil rigs and other equipment in some high-power crankshaft, a variety of heavy vehicles used in oil fields, tractors, diesel engine crankshaft and other wear can be used after thermal spraying technology to repair. Such as arc spraying 3Cr13 coating or plasma spray ceramic coating to repair. This can significantly reduce costs, but also extend the service life of equipment, in particular, can effectively solve the repair problems of imported equipment. Thermal spray method can also be used to restore ultra-poor parts processing or wear-resistant parts of the surface.
Various types of pumps used in the oil pump plunger, cylinder liner, impeller and other parts can be used a variety of thermal spraying method to repair. Such as the use of supersonic flame spray WC-12Co or plasma sprayed Al2O3 to repair and strengthen, can also be used arc spraying 1Cr13 steel wire repair. The service life of the plunger repaired by thermal spraying is higher than that of the surface quenched plunger, slightly lower than that of the nickel-base alloy sprayed on the working surface. For some large-diameter plungers, thermal spray can be the best solution for deformation-free, low-cost repairs that can not be done by spray welding due to deformation. China has repaired a 12 tons of plunger, spray coating weighs 33 kg, the coating for sealing treatment, the use of performance better than the new plunger, and the cost of only the new plunger 14. Oilfield water injection pump motor and oil refining, salinization system using high-power motor rotor, thermal spraying technology can be used to repair the wear of the journal parts.
2. Improve the wear resistance of mechanical parts
Generally use flue gas energy recovery system. However, since the flue gas turbine is a catalytic cracking unit with solid catalyst particles and an etchant oil refinery, the quality of high temperature flue gas flow down, its moving, static blades and other parts vulnerable to erosion, and its service life of only 2 to 12 months. The use of plasma spraying technology in moving, static blade surface spraying alloy powder, can improve dynamic and static blade erosion wear resistance, thereby extending the life of gas turbine.
3. Spraying oil machinery parts
Wear-resistant corrosion-resistant ball valve: For work in temperatures up to 540 ℃, pressure up to 140MPa corrosive mortar pipe metal seat ball valve, the application of supersonic flame spraying WC-Co coating, Cr2C3-NiCr coating, Fe-Cr -Ni-Mo coating or WC-Ni coating can greatly improve the ball valve corrosion and erosion resistance, improve the reliability and life expectancy. Sucker Rod: In order to meet the needs of the production of corrosive oil wells, the United States used AISI431 stainless steel material to produce stainless steel sucker rod, which is characterized by good corrosion resistance but high cost. To save costs, Continental Oil Company of the United States utilized AISI 316 stainless steel powder to plasma-spray API grade C and D sucker rods to create a spray-painted stainless sucker rod that is also corrosion resistant but less costly than stainless steel It is cheaper Pump plunger: Domestic oil well pump piston processing methods are: the surface of chrome, electroless nickel-phosphorus and surface spray nickel-based alloy. Currently, thermal sprayed ceramic coatings have been used as a new treatment process to make pump plunger. A ceramic coating was formed by spray coating 87% Al 2 O 3 + 13% TiO 2 on the plunger surface by thermal spraying technique. Pump plunger made by this method. In sand wells up to more than two months. Its life expectancy is twice the plunger made by the traditional process. Bits: Blast Spray WC-Co coatings are used successfully in drill bits to improve the bit's resistance to abrasion, corrosion and abrasion. Plasma coating can also be used to produce composite alloy coatings on synthetic diamond drill bits.
4. Containers, pipes and tower anticorrosive oil field tower, cans, pipes can be used arc spraying aluminum, zinc, stainless steel coating corrosion or flame spray anti-corrosion. DuPont, United Chemical, Shell and other companies in the reaction generator wall has been extensive use of wire spraying stainless steel, Stellite alloy, molybdenum and titanium alloys. The use of plasma spraying, supersonic flame spraying, arc spraying can be used to solve a variety of oil field boiler corrosion and erosion problems.