Warp and weft anti-wear

Analysis of energy-saving warp and weft anti-wear technology documents and commonly used anti-wear methods for circulating fluidized bed boilers at present

1、 Disadvantages of thermal spraying:

Due to the relatively late use and wide geographical area of sulfide bed boilers in China. Due to the diverse forms of coal used, the reasons for wear and tear are also different. So far, no suitable method has been found to deal with wear and tear. Many home appliance factories across the country now use thermal spraying method. According to relevant statistics, 65% of sulfide bed boilers in China adopt thermal spraying measures (mostly)

For CFB12MW-300MW, the satisfaction rate is only 30%. Some are also affected by thermal spraying measures, resulting in many legacy issues.

The specific drawbacks are:

Firstly, the selection of thermal spraying materials is quite non-standard. And the market is quite chaotic. It is quite difficult to repair welding once the pipe bursts. Because the chemical composition and stress of each material are not very integrated with each other. Because thermal spraying is mainly based on mechanical interlocking, the impact performance of the coating is not high. Many manufacturers have a headache when it comes to repairing welding after a pipe burst.

Problems discovered during the six-month maintenance of spraying

2、 Disadvantages of deposition technology:

Cladding is a new surface modification technique that involves adding cladding material to the surface of a substrate and using a high-energy density laser beam to melt it together with a thin layer on the substrate surface, forming a metallurgical bonded cladding layer on the substrate surface.

Laser cladding refers to the process of placing selected coating materials on the surface of the substrate to be melted simultaneously with a thin layer of the substrate surface by laser irradiation using different additive methods, and rapidly solidifying to form a surface coating with extremely low dilution and metallurgical bonding with the substrate. This significantly improves the wear resistance, corrosion resistance, heat resistance, oxidation resistance, and electrical properties of the substrate surface, thereby achieving the purpose of surface modification or repair. It not only meets the specific performance requirements of the material surface, but also saves a lot of valuable elements. But if the current adjustment is not scientific, sometimes the current situation can also be disrupted.

But the price is six times higher than other wear-resistant measures, which is difficult for ordinary units to accept. Its external construction is quite slow, which poses a test for the heavy and tense power plant repair work.

3、 Working principle of energy-saving warp and weft anti-wear:

The new technology of Bayer energy-saving warp and weft wear-resistant water-cooled wall is to install warp and weft plates vertically and horizontally in layers on the four walls of the furnace, effectively guiding the wall attached flow carrying materials to wash the water-cooled wall up, down, left, and right. This achieves the goal of changing the flow direction of the material flow, reducing the flow velocity of the material flow, isolating the adjustment and collision between the material flow and the water-cooled wall, greatly reducing the cutting wear of material particles on the water-cooled wall, and fundamentally solving the problem of water-cooled wall tube wear.

The new technology of warp and weft type water wall anti-wear has been adopted by multiple boilers. Operational practice has proven that the installation of warp and weft type anti-wear on the water wall significantly reduces wear, and the annual wear of the water wall tube does not exceed 0.1mm during continuous operation. Especially in the transition zone of the casting material, no other anti-wear measures are used, and there is no trouble of shutdown due to water wall wear and leakage. This has enabled the circulating fluidized bed boiler to transition from frequent unplanned shutdown maintenance to a good state of continuous and safe operation.

Characteristics and installation examples of energy-saving warp and weft wear-resistant technology

4、 Characteristics of energy-saving warp and weft wear-resistant technology:

1. The essence of the warp and weft anti-wear new technology is to guide the particle materials in the furnace, form internal circulation, change the flow direction of the material surface wall and the vortex flow direction of the material particles at the four corners of the chamber, so that the material flow tends towards the center, avoiding collision with the water-cooled wall, and thus curing the contact wear of the wall flow angle vortex on the water-cooled wall.

2. The warp and weft type technology uses high-temperature resistant and wear-resistant multi-element alloy casting, which can withstand high temperatures up to 1250 ℃ and has a tensile strength of ≥ 560Mpa. This material is well matched with the warp and weft type water-cooled wall anti-wear process, ensuring a service life of more than 6 years from a material perspective.

3. The warp and weft type is mainly installed in the dense phase zone around the furnace. As it is made of metal material, it enhances the heat conduction energy to a certain extent, so it will not have any negative impact on the load capacity inside the boiler.

4. The warp and weft type can effectively disrupt the vortex formed by the material flow on the uneven pipe wall, reduce the collision between material particles and the water-cooled wall, avoid the wear of solid materials on the water-cooled wall tube, and protect the water-cooled wall.

5. The warp and weft layered installation around the furnace can effectively reduce the speed of material particles falling along the water-cooled wall tube, isolate the contact between the material flow and the water-cooled wall tube, and fundamentally solve the problem of water-cooled wall tube wear.

6. Easy installation and short construction period. Taking a 240 ton boiler as an example, the construction period only takes 3 days.

7. Scientifically integrate a 12cm x 1.2cm blue mud skirt at an appropriate position on the horizontal baffle of the warp and weft wear-resistant layer, fully protecting the erosion of the upper baffle pit and playing a "ladder" type wear-resistant role. In addition, blue mud is filled in the gap between the semi-circular horizontal baffle and the water-cooled wall tube to prevent the accumulation of fly ash without leakage.

5、 Anti wear mechanism of energy-saving warp and weft type water-cooled wall:

The warp and weft type process is based on the principle of "dredging" and "guiding" the internal circulation of materials. It is equipped with warp and weft type flow deflectors to reduce the terminal velocity of poor particles falling along the water-cooled wall tube, isolate the material flow from contact with the water-cooled wall tube, destroy the eddy current formed by the material flow at the uneven and smooth tube wall, reduce the collision between material particles and the water-cooled wall tube, and thus avoid the wear of solid materials on the water-cooled wall tube, which plays a temporary and fundamental role in preventing wear of the water-cooled wall tube. The anti-wear principle can be summarized as follows:

1. Disrupting the stable edge wall zone reduces the particle concentration of the dense phase edge wall flow in the furnace, reducing the chance of particles coming into contact with the water-cooled wall.

2. When the downward flowing particles slide down to the wear-resistant warp and weft type, the sliding speed decreases by nearly 0 before starting to descend again. The distance between each layer of wear-resistant warp and weft type is greatly reduced compared to the original furnace height, that is, the sliding height of the particles is greatly reduced. Therefore, greatly reducing the particle flow velocity greatly reduces the wear of particles on the wall, and the wear is reduced to almost the same level as coal powder.

6、 Practical application of energy-saving warp and weft anti-wear:

The wear-resistant measures are taken by constructing a circle of wear-resistant warp and weft type along the circumference of the furnace at regular intervals on the membrane water-cooled wall above the wear-resistant material in the furnace, similar in style to miniature wear-resistant beams. Starting from the end of the wear-resistant casting material, vertically upward 20mm At 720mm, 1700mm, 2800mm, 4200mm and other 5 locations, install a circle horizontally along the inner membrane water-cooled wall of the furnace. The latitude and longitude dimensions designed and manufactured according to the outer diameter and spacing of the water-cooled wall are 260mm * 60mm * 6mm, with a latitude and longitude style. The material used is heat-resistant cast steel, and the latitude and longitude shapes are horizontally spot welded to the membrane wall fins. The latitude and longitude shapes are overlapped (not welded considering expansion factors).

Example diagram of energy-saving warp and weft wear-resistant water-cooled wall with large and small walls

7、 Installation instructions for energy-saving warp and weft anti-wear:
The cross plate (comb plate) of the new technology and new process adopts the wave compound welding method, with spot welding on the top and spot welding on the bottom. Mastering the hot expansion joint treatment technology in welding, that is, mastering the technique of latitude and longitude balance; Master the plane slope of welding; Master the treatment of thermal expansion joints. Beyond the range of thermal expansion joint, the welder uses other materials to enclose the joint to solve the problem. Vertical plate welding adopts vertical welding from top to bottom, with uniform spot welding at the upper, lower, left, right, and middle corners as the standard. During welding, welders should remember not to collide with pipes or pull arc pipes (there should be no marks on the pipes after the project is completed). The curvature of the warp and weft plate is clamped on the pipe, and the welding points are unified on the fins, with their welding points on the warp and weft plate. The welding rod is made of heat-resistant steel A402 with good toughness, and the welding point is firm and does not fall off. The new technology and new process water-cooled wall adopts a warp and weft type for wear prevention, which must be constructed in conjunction with blue mud material. Its main function is to supplement the wear of the pipe parts, and the temperature is suitable for naturally filling the unevenness and original damaged surface. In recent years, our company has undertaken projects that use the new technology and new process water-cooled wall to install warp and weft type boilers for protection. Practice has proved that the warp and weft type is used in conjunction with blue mud material for construction, and its wear prevention effect, annual thickness measurement record, and internal wear protection do not exceed 0.1mm. The anti wear function of the warp and weft type is to remove solid particle materials, but it can also cause collision and click on pipes. By using blue clay material, it is possible to repair and supplement the worn and cracked areas of the pipes. Therefore, it is necessary to carry out supporting construction in order to present a good anti-wear effect

Example diagram of using Bayer energy-saving warp and weft wear-resistant water-cooled wall

Analysis of warp and weft wear-resistant plate materials:

analysis	tombarthite	silicon	manganese	phosphorus	sulfur	chromium	nickel	molybdenum	carbon
result	0.９2	0.９6	7.52	0.09	0.09	23	7	0.3	0.2

8、 Characteristics of Blue Mud:
Characteristics and parameters of SIRPLAST PH 70 MU

Product type: Plastic mixture	Main component: Alunite
High operating temperature: 1600 ℃	Packaging: 25kg/box
Shelf life: 18 months	Calculation of required materials: 2.65 tons/cubic meter

Example diagram of using blue mud skirt shaped wear-resistant material

9、 Currently, there are several commonly used wear-resistant and cost-effective options for circulating fluidized bed boilers:

 

product name	Excl. Tax ㎡∕（YUAN）	Usage time (year)	note
Thermal spraying	1000--1600	1	Shedding, short time
Anti wear tile	2000	2	Detachment. Affects heat transfer
Anti abrasion coating	1000	6 months	Poor effect
Anti wear beam	1500	3 months	Affects the operating rules. Longitudinal non wear-resistant
Fusion deposition technology	6000	4	High price, slow speed
Warp and weft anti-wear	1200	5	Time is constant. Vertical and horizontal anti-wear

10、 Quality Assurance:

1. The quality assurance period is three years and the usage period is five years.

2. The investment cost is only 1/5 of thermal spraying and 1/6 of deposition.

3. Thoroughly solved the lateral wear caused by smoke corridors.

4. Fully increase the carbon content of coal combustion. 5. Can ensure the anti-wear effect of welds and dead corners. 6. There are no negative effects. 7. Completely solve the wear caused by uneven surface of the pot

Note: This price is a reference price, determined based on the project manager's arrival at the construction site, on-site investigation of the construction site, working conditions, environment, and area.