What Kind Of Refractory Castable Is Used For Lining The Large Flue Windbox?

What kind of refractory castable is used for lining the large flue windbox?

The chimney lining belongs to an acidic atmosphere, which is mainly caused by acid gas erosion and erosion. The lining is generally made of acid-resistant refractory castables, and the construction thickness is about 100mm

1. Different heights require different construction methods

Because the chimneys have different heights, the construction methods are also different. Some are constructed on the ground and then hoisted and installed in the middle. Some of them are constructed directly from high places. If the chimney is too high, construction will be very difficult. However, cracks or cracks will appear in the chimney lining needle after construction, and the cracks and cracks will gradually expand, sometimes even extending to the entire chimney lining. In some cases, there is peeling or bulging.

2.There are four reasons

There are four reasons: first, it is caused by temperature difference stress in the chimney; second, it is caused by shrinkage stress; third, it is caused by inconsistent shrinkage of the joint surface of acid-resistant refractory castable materials. Fourth, the binder was forgotten to be added when stirring the acid-resistant castable. When these four situations occur, repair them in time. For the bulging areas, stir the acid-resistant castable and chisel them out directly before pouring to fill them. When filling, they must be dug in a dovetail style, that is, small at the top and large at the bottom. This is beneficial. connect.
If vertical cracks are seen after removing the formwork, it is because the formwork was removed too early. If found during removal, it can be repaired immediately.
For circumferential cracks that appear, you must wait for the crack to stabilize, about 45 days, clean up the debris around the crack, and use an iron drill to shovel out the crack. Two-thirds of the thickness of the acid-resistant refractory castable is equal to the width of the crack on both sides. Each tent is 50mm thick and should be filled with acid-resistant castables remaining during construction.
Repair is only a remedial method, but construction prevention is fundamental. During construction of acid-resistant shallow pouring materials, additives must be added. 3 hours after proper pouring and demoulding, use a 2.5~3.0mm thick toothless saw to pull out the expansion joint. The expansion joint is 1500mm × 1500mm and the seam depth is 2.5mm. This prevents the occurrence of cracks.

3. Demold for no less than 10 hours and do not stir too thinly.

In addition, the demoulding time of acid-resistant refractory castables cannot be less than 10 hours, and the demoulding time or the strength of the castables when demoulding is strictly controlled. Avoid premature demoulding and cracks. If it is a dark corbel position, the acid-resistant castable must not be mixed too thinly, and the proportion of binder must be strictly adhered to to ensure that no cracks occur during the construction of the dark corbel high up in the chimney.