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Influence of unqualified refractory castable on boiler

Posted time:2021-10-22 Page View:124

One of the reasons for unqualified boiler construction is that the design of refractory and anti-wear structure is not perfect or the quality of wear-resistant refractory castable is not good.

First, refractory and wear-resistant material expansion joint design is unreasonable. Due to the design number of circular and longitudinal expansion joints is not enough or other reasons, resulting in the volume expansion of the wear-resistant refractory materials of the boiler after heating, extrusion each other, crack.

1, the expansion joint at the connection of wear-resistant refractory castable and firebrick of the inlet flue of the cyclone separator is widened appropriately considering casting factors, from 5mm to 10mm, and sufficient clearance is reserved to meet the expansion requirements. The expansion joint is changed to Z shape to prevent the gap from running through directly and causing the ash to wash the insulation layer. Expansion joint filling material requires kraft paper layer refractory fiber felt on both sides to prevent cement slurry from immerging directly into the filling material, curing and occupying the expansion space of the expansion filling material. The design interval of annular expansion joints was changed from 1500mm to 1000mm.

2. In large areas such as separator outlet flue and separator cone, the pouring surface is changed from (2.5mx25m) to small square (1.5mx1.5m) -- forming masonry, and the expansion joint is set, the width of the expansion joint is ≤3mm. The filling material requires strong rigid plywood to prevent deformation when tamping. After the boiler runs, the plywood is burned at high temperature and the space becomes an expansion seam.

3, cyclone separator barrel along the height direction is provided with brick lining support plate, in order to achieve the purpose of layered unloading of brick wall, through the weight calculation of the actual firebrick barrel, the design of a layer of support plate can not achieve the purpose of unloading, according to the actual situation of the site support plate is changed to two layer layout.

The nails in the boiler are welded on the air distribution plate, slag discharge pipe, air duct and other metal plate, the expansion coefficient of the nail after heating is far greater than the expansion coefficient of refractory material. If the nail is not pretreated with asphalt, but directly in contact with refractory casting, the contact surface of the metal material and refractory is bound to form a network of micro-cracks, resulting in the final cracking and falling off of refractory. Remove grease and ash stains when refractories contact metal surfaces, and evenly apply asphalt of more than 0.5mm. To ensure the concentration of asphalt and daub thickness, resolutely put an end to using asphalt paint instead of asphalt to do nail coating paint.

Second, the quality of refractory and wear-resistant materials is not up to standard or the storage is not good, and the matching and combination of the aggregate and matrix of wear-resistant materials have an important impact on the wear resistance of materials. The mismatch of aggregate and matrix will lead to cracks in the material body after forming. The poor binding between aggregate and matrix will lead to the erosion of matrix, and then the aggregate is isolated, and then fall off. So to ensure the quality of aggregate and matrix, the selection of appropriate binder and additives is very important. Different material manufacturers, there are different batchings, but for users: ultimately to ensure the performance indicators of wear-resistant refractory materials, ensure that the quality of materials pass, to meet the requirements of various parts of the boiler operating conditions and expansion indicators.

In addition, wear-resistant refractory materials over the storage period (3 ~ 6 months, generally not more than 3 months to use the best effect), material failure, improper preservation of some materials, damp deterioration, will also cause boiler masonry quality is not qualified.