Application of new wear prevention technology for water wall of boiler

Reheater damage is the most serious damage of circulation fluidized bed boiler, especially in refractory castable cohesive zone, spray coating edge, corners in furnace with refractory castable position fell, spraying layer peeling, reheater tube after changing a fins is not smooth, the hole door, measurement point let tube place with a regularity of damage and leakage problems.

Improvement of corrosion prevention technology of reheater:

New maintenance and processing technology and subsonic arc spraying anticorrosion technology are selected

1. Clean the surface: remove all kinds of air pollutants on the sprayed surface, especially vegetable oils, stains, oxide scales, rust and etches. The cleanliness of the working table should be GB8923-88 "stainless steel plate surface rust level and rust removal level" in the requirements of SA3.0 level.

2, surface sandblasting: the fusion of thermal spraying coating and substrate is dominated by mechanical equipment fusion, which stipulates that the substrate is not only to be oil and rust prevention treatment, but also needs to be passivated surface treatment, application surface has a certain surface roughness. The surface roughness should be RZ60 ~ 90μm as required in GB11373-89 "Surface Preparation Rules for Thermal Spraying Metal Products", which is not easy to cause any damage to the wall thickness.

The purpose of sandblasting solution:

A. Expand the total area of contact between the spraying layer and the substrate to improve the adhesion adsorption of the fusion surface.

B. Improve the mutual chimera between the coating raw material and the substrate surface and the teeth bite, which has the effect of "anchor hook" to improve the adhesion force between the coating and the substrate.

C, active surface: sandblasting gives the dynamic surface working ability to paint: such as lattice constant defects, plastic deformation, resulting in a certain in-situ stress, in order to improve the adhesion force of spray paint particles and matrix surface, improve the painting particles and matrix of micro-metallurgy industry fusion work ability. The activity effect analysis is as follows:

D. Sandblasting produces a certain residual compressive stress on the surface of the workpiece after continuous severe attack by sand particles. Although the stress level is very small, it is beneficial to improve the fusion compressive strength of the coating for relaxing the internal stress of the coating in the whole process of painting, and at the same time, it can also improve the fatigue limit of the workpiece.

E, spray paint can remove the organic chemical air pollutants and air oxide layer on the surface of the workpiece, and can expand the plastic deformation of the crystal on the surface of metal materials and lead to the defects of lattice constant, so that the surface of the substrate is very easy to produce chemical changes, which is conducive to the physical fusion strength between the spray paint particles and the substrate surface.

F. Sandblasting shows that: Sandblasting spray only in addition to the dirt on the surface of the dirt, the spray in addition to the thick wall thickness of 15 microns or less, the bao hou thin, for thick wall thickness is not easy to damage, all times sandblasting job is not easy to cause crack and blowing loss of wall thickness, sand blasting work is symmetrical, all its thickness on the surface of the drop to compensate is consistent, generally sand blast work for furnace only be dry mania, cleaning, and active surface, It is the most practical way to improve the fusion compressive strength of the coating, and it is not easy to damage the wall thickness.

Therefore, it is extremely necessary to carry out sandblasting solution before the workpiece is painted. And the workpiece after sandblasting should be sprayed as soon as possible, the less time surface activity the better the actual effect, the higher the quality of the coating.

Choose new maintenance process and subsonic arc spraying anti-corrosion technology, greatly ease the damage condition, heating furnace operation cycle time was stopped by the original average of 30 days time, once done now average 50 days, stop boiler furnace maintenance cycle time obtained reasonable increase, cut its full-year boiler stop frequency of 4 times.

Estimated economic benefits:

Each furnace shutdown harms economic benefits: maintenance labor cost of 23,000 yuan Heating furnace shutdown damages economic benefits of more than 723,800 yuan = 746,800 yuan

After reheater painting, the heating furnace is reduced 4 times every year because of reheater leakage and the furnace shutdown may increase the economic benefit by more than 2,987,200 yuan