Why the Service Life of Honeycomb Ceramic Heat Storage Bodies Not Long?
What are the reasons? Why the service life of honeycomb ceramic heat storage bodies not long? At present, the service life of honeycomb ceramic heat storage bodies is not very long. The main problems that occur during use are melting, softening, rupture, blockage, and corrosion. There are special cases where a large amount of fragmentation occurs after only one week of use, and there are also those whose service life reaches 2 years due to the large heating capacity or the low service temperature. However, the service life of most heat storage heating furnaces is generally 8-12 months, and the average life is generally short. Common reasons for damage to the honeycomb ceramic heat storage body and short lifespan are analyzed as follows:
- Small hole blockage
Blockage of small holes is one of the most common causes of damage to the honeycomb ceramic heat storage body. After the small holes of honeycomb ceramic heat storage bodies are blocked, it not only directly causes a significant reduction in its heat storage and smoke exhaust performance. It also causes uneven smoke exhaust and heat exposure of the honeycomb ceramic heat storage, which can easily cause cracks and aggravate its damage.
- Low load softening temperature
If the load softening temperature is low, during long-term use in normal high temperature environments or when abnormal high temperature occurs, the lower honeycomb ceramic heat storage body will not be able to withstand the combined effect of high temperature and load, and will soften, compressive deformation. This causes the row of honeycomb ceramic heat storage bodies to collapse, and even causes the adjacent honeycomb ceramic heat storage bodies to collapse together, resulting in the blockage of the lower heat storage chamber. The upper part forms a high-temperature channel gap without honeycomb ceramic heat storage body, and the high-temperature flue gas is directly discharged. The heat in the flue gas cannot be effectively recycled, the smoke exhaust temperature is high and the heating capacity is significantly reduced.
- Local high temperature and secondary combustion
Under normal circumstances, although the furnace temperature exhaust gas exhaust temperature does not exceed 1300℃, the combustion temperature of the flame is much higher. According to the fuel combustion temperature calculation, when the blast furnace gas is preheated to 1000℃, its flame combustion temperature can reach 2400℃. The flame combustion temperature of high-calorie gas fuels, such as natural gas and acetylene, can be as high as 3000℃. Therefore, when secondary combustion or local high temperature channels appear in the heat storage chamber, the temperature it receives has exceeded the load softening temperature and the refractory tolerance limit. The honeycomb ceramic heat storage body will naturally soften, even shrink holes, or severe ablation into clusters.
- Poor corrosion resistance and poor slag resistance
The honeycomb ceramic heat storage body near the first row of the high temperature side reacts with the molten iron oxide or iron oxide small particles brought by the flue gas. The crystal phase inside the honeycomb ceramic heat storage body changes, causing the refractory resistance, load softening temperature, and slag resistance to a sharp decline. Adhesion, shrinkage, blockage or even collapse occurs between each other.
- Poor ability to withstand cold and heat
Due to the frequent heat storage and heat release of honeycomb ceramic heat storage bodies, the temperature changes are severe, causing the walls of the honeycomb ceramic heat storage bodies to be subjected to tensile and extrusion stress alternately. And cracks are generated by the action of thermal stress, and severe fractures will occur. At the same time, collapse will also occur, resulting in the blockage of the lower part of the honeycomb ceramic heat storage body and a hollow space on the upper part, which cannot be used normally. Therefore, the working characteristics of the honeycomb ceramic heat storage body with frequent changes in heat force are the main reasons for its shorter life.
- Poor volume stability at high temperature and large deformation of refiring
During use, most honeycomb ceramic heat storage bodies are installed in cold state and used in hot state. Since the honeycomb ceramic heat storage body has poor high temperature volume stability and large refiring deformation and shrinkage, a gap without honeycomb ceramic heat storage body will be formed on the upper part of the heat storage chamber during use. At this time, the honeycomb ceramic heat storage body itself is not damaged, but most of the flue gas slips directly from the upper gap and gradually forms a high-temperature channel in the upper part of the heat storage chamber. The high temperature causes the nearby honeycomb ceramic heat storage body to rupture, and the channel further expands, thereby accelerating the rupture and damage of the honeycomb ceramic heat storage body.
- Biased flow problem
In the heat storage chamber, the heat exchange process is roughly as follows: in the exhaust stage, when the flue gas flows through the honeycomb ceramic heat storage body, the sensible heat is stored in the honeycomb ceramic heat storage body, heating the honeycomb ceramic heat storage body. In the combustion stage, the air (or gas) is heated when it flows through the honeycomb ceramic heat storage body, and the residual heat is brought back to the furnace. In any of the above stages, if the gas has a biased flow in the heat storage chamber, after several reversals, it is easy to cause local high temperature of the honeycomb ceramic heat storage body and generate thermal stress. When the temperature stress generated exceeds its tolerance limit, the honeycomb ceramic heat storage body will break.
- Fire barrier brick problem
The fire barrier brick plays a dual role of fixing and fire barrier protection for the honeycomb ceramic heat storage body, so it also has an important impact on the service life of the honeycomb ceramic heat storage body. If the material selection or shape and size design of the fire barrier brick is improper, there will be problems such as low brick strength or excessive gap, which will cause the honeycomb ceramic heat storage body to directly contact the flame or secondary combustion. As a result, the honeycomb ceramic heat storage body is prone to rupture, collapse, melting, softening and other problems.
- Influence of water vapor in gas pipeline
When a large amount of condensed water is precipitated from the end of the gas pipeline and enters the heat storage chamber, or when the cooling water pipe in the furnace breaks and flows into the heat storage chamber along the furnace wall, the heat storage body in a high temperature state is very easy to break when encountering liquid water. At the same time, when water enters the heat storage chamber, the viscosity of dust impurities in the fuel gas and iron oxide powder in the flue gas increases, and chemical changes occur, increasing the corrosiveness of impurities. Therefore, it is easy to cause blockage and corrosion of the honeycomb ceramic heat storage body, which accelerates the shortening of the service life of the honeycomb ceramic heat storage body.
