How to test the wear of refractory brick in rotary kiln lining without damage?

September 01, 2018

Refractory material plays a vital role in the production of cement clinker, while refractory bricks are the most important. It not only plays a role in the heat insulation,makes the materials absorb more heat in the kiln evenly, but also protects the kiln. So as to avoid direct contact with high temperature materials.However, due to the long term high temperature and erosion environment, and as a consumable material, there must be a certain life cycle.When the performance of the refractory brick does not meet the production requirements(such as brick thickness is too thin), it needs to be replaced in time. In actual production,the thickness of refractory brick in the kiln is an important indicator when replacing. 

For example, a 2500t/d clinker production line, rotary kiln size 4m*56m.Measuring the thickness of the refractory bricks in the kiln has become a must to check items for downtime maintenance.Every time of the maintenance.there is a part of the plan for changing bricks. In the past, the manual measurement was carried out, the worker holds the electric drill into the rotary kiln and directly drills through the refractory brick for measurement. Not only have the risk of the personal,but also the heavy workload and the serious dust pollution. ( using electric drills to drill holes can cause deep damage to refractory brick, and easily cause cracks to affect the service life). Direct measured by the instruments,the price of instrument is expensive. Today we will introduce a simple and effective method for measuring the thickness of the bricks.

Method of measuring the thickness of brick

The longitudinal section of the refractory brick used in the rotary kiln enterprise is an isoseles trapezoid, as shown in Figure 1.

Refractory

The front view size of a standard refractory brick, the height is H, assuming a wear occurs for a period of time, the new section length is L, the unknown thickness of the brick is h. According to the area method,the thickness of the brick can be calculated by the known or measurable data, and the thickness of the brick is h:=(B-L)*HI(B-A),and A is the upper bottom side of the new refractory brick. B is the length of the lower base of the new refractory brick. L is the length of the top edge measured after the refractory brick is worn. H is the height of the new refractory brick.

In this way, as long as the L is measured in the kiln during the overhauled, the above formula is set up with EXCEL form and L is input. The thickness of required brick can be obtained. 

This saves time and reduces labor intensity. This measurement method is suitable for all wedge bricks.

Precautions in measurement

In order to ensure the accuracy of the measurement results during the measurement process, we need pay attention to the following items:

1. During the process of measurement, if the refractory brick in the measurement position is not directly exposed, and the surface covers the kiln coating,the kiln coating should be cleaned first, and the surface of the refractory brick should be cleaned with a steel brush to completely expose the gap between the brick and the refractory brick should be completely exposed.

2.Due to different kiln diameters,there are differences in the proportion of refractory bricks. In order to ensure the accuracy of the measurement,it is necessary to measure the adjacent refractory bricks at the same time.

3.When measuring the refractory brick of static equipment( tertiary air duct, precalciner etc), because the inner surface is relatively flat, if there is a crust, the crust should be removed first and then measured. If the crust does not crust, the refractory brick is exposed,it can be measured directly.

4. If the refractory brick are uneven, in order to reduce the error, it’s recommended to use manual drilling measurement to observe the internal structure and find out the cause of non periodic wear of the refractory brick.

This measurement method is an easy way to supplement the previous drill hole punching measurement. After using this method to measure and compare the drill hole measurement (rotary kiln refractory brick) during maintenance, it is found that the measuring deviation in rotary kiln is about 5~8mm.

After tertiary air duct refractory brick was measured by this method, the refractory brick was removed and directly measured using a ruler. It was found that the measurement of deviation of the tertiary air duct refractory brick was about 3~6mm. Since the maximum error did not exceed 1 cm, the measurement results can be accepted.

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