Common causes of damage to thermal storage bricks

In the process of use, thermal storage bricks must be subjected to high temperatures, rapid temperature changes, atmospheric changes, and erosion by dust, smoke, molten metal and molten slag, so it is very likely to be damaged, which makes it difficult for us to judge the end What causes the thermal storage bricks to be damaged, then let's take a look at some analysis methods given by experts.

The damage of thermal storage bricks during use is not only due to slag erosion (continuous type), but also to factors such as fracture and peeling (discontinuous type). After comprehensive analysis of the use results of thermal storage bricks, the damage mechanism of thermal storage bricks can be classified.

Classification of the damage mechanism of thermal storage bricks

1. Continuous erosion

1) Melting and gasification on the surface:

Diffusion in molten phase, gas phase, melting phase, interface between gas phase and brick

2) Melting and gasification from the inside of the brick: molten material, gas-phase components penetrate and melt, and gasified components are discharged to the outside

2. Discontinuous erosion

1) Cracks occur:

Formation of low-density phase by reaction with permeate, phase transfer with volume change, local shrinkage and thermal stress concentration caused by reheating

Local concentration of bubbles, concentration of mechanical and thermal stress on the structure, anisotropy of thermal stress and elastic modulus of constituent phases

Precipitation and deposition caused by the reaction between rhenium and gas phase, mechanical impact.

2) Local presence or formation of high melting, high vapor pressure or low viscosity phases

3. Loss due to wear

方式 The damage modes of refractory materials in use can be summarized into three basic forms.

1) Due to the mechanical stress and thermal stress of the structure, the refractory work lining generates irregular cracks (thermal, mechanical peeling or chipping) and is damaged.

2) Due to the infiltration of slag and temperature fluctuations on the hot surface (working surface), the structure of the refractory material is changed, so a unique metamorphic layer is formed, and a crack parallel to the heating surface is generated at the interface between the metamorphic layer and the metamorphic layer. (Fractured) and damaged.

3) Dissolved flow and wear due to reaction with molten metal, slag and soot, mainly because the working surface layer is eroded (melted) due to the generation of liquid phase.

Refractories are actually thermodynamically unstable during use. Therefore, the research and development direction of refractories is to establish a dynamic barrier in (and near) the refractories to resist the deterioration caused by irreversible structural and composition changes.

From the perspective of phase equilibrium or thermodynamics, there is no component that does not react in the thermal storage brick that is in contact with the slag. Therefore, a protective layer is formed on the surface of the refractory material, and the dissolution rate of the protective layer is slowed down as much as possible in order to control the damage caused by slag erosion to a minimum. In order to reduce the dissolution (diffusion) speed of the protective layer, the components of the protective layer should be high-melting-point substances or high-viscosity solutions in which the slag and the heterogeneous heterogeneous equilibrium are close to each other as much as possible. The so-called heterogeneous heterogeneous phase balance means that one or two or more components change into two or more different phases and coexist in equilibrium. For example, at a certain temperature, when MgO is melted in the slag to a certain amount, MgO is no longer melted. At this time, the melt and MgO are in a heterogeneous heterogeneous equilibrium relationship.

The results of use have repeatedly proven that eliminating the damage of methods Ⅰ and Ⅱ and reducing the speed of the damage are always the goals we pursue for the thermal storage brick research institute.

Assuming that the damage caused by the irregular cracks of the thermal storage brick can be eliminated, it is possible to evaluate the thermal storage brick in advance.

As already known, damage methods I and II are common defects of alkaline and high-alumina heat storage bricks. However, since the development of carbon-composited oxide refractories, the damage can be limited to the working surface layer of thermal storage bricks, indicating that problems that cannot be solved for a long time in the category of oxide thermal storage bricks, and non-oxide composites Can be solved in the oxide thermal storage brick.