Chain grate is a common combustion equipment in industrial boilers. During long-term operation, affected by various factors, it is prone to various faults. In severe cases, it will affect the normal operation of the boiler, reduce production efficiency, and even cause potential safety hazards. The following is an in-depth analysis of several common faults.
I. Deviation of the Grate
(I) Fault Phenomenon When the chain grate is running, it shifts to one side as a whole, causing the grate to frequently rub against the side plate of the furnace body, emitting abnormal sounds. There may be wear marks at the severely rubbed area. The smooth operation of the grate is disturbed. In severe cases, the grate will get stuck and cannot rotate normally.
(II) Cause Analysis
1. Installation Issue: During the equipment installation process, if the parallelism of the front and rear axles fails to meet the standard requirements, or the axle shafts are excessively bent, the force on each part of the grate during operation will be uneven. For example, if the front axle tilts to the left and the rear axle remains horizontal, the grate will be subjected to a leftward component force during operation, thus gradually shifting to the left.
2. Improper Adjustment: The adjusting nuts on both sides of the grate are not tightened to the same extent. The side with a tighter nut has a greater pull on the grate, and the grate will skew to this side. Suppose the left adjusting nut is tightened two more turns than the right one, the grate will gradually skew to the left during operation.
3. Component Wear: The chain and the sprocket engage and operate for a long time, and the sprocket will wear, especially the tooth part. When the sprocket wears severely, its meshing with the chain is no longer tight. The chain is prone to sway left and right during operation, thereby causing the grate to deviate.
II. Falling of Grate Bars
(I) Fault Phenomenon During operation, the grate bars fall off the chain. Sometimes it is a single grate bar that falls off, and sometimes it is a group or several groups of grate bars that fall off together. This will cause vacancies on the surface of the grate, and the fuel cannot burn normally in this area, affecting the combustion efficiency and possibly causing unstable operation of the grate.
(II) Cause Analysis
1. Quality Defect: The grate bar itself has poor material quality. For example, if the carbon content is too high or too low, its mechanical properties do not meet the standard. It is prone to fracture when subjected to high temperature, heavy pressure, and frequent friction. At the same time, the manufacturing process is not up to standard. For example, there are defects such as sand holes and pores during casting, which will also reduce the strength of the grate bars.
2. Installation Error: When installing the grate bars, the pins are not correctly installed in place and there is a loosening phenomenon. During the operation of the grate, under the action of external forces such as vibration and impact, the pins gradually come out, causing the connection between the grate bars and the chain to fail, eventually leading to the falling off of the grate bars.
3. Long-Term Loss: With the increase in usage time, the grate bars are constantly affected by factors such as high temperature and wear. The metal material gradually ages, fatigues, and the strength and toughness decrease, eventually leading to the damage and falling off of the grate bars.
III. Arching of the Grate
(I) Fault Phenomenon During operation, the grate bars arch upward, making the surface of the grate no longer flat. The operation of the grate is hindered, the forward speed is uneven, and it may even get stuck due to severe arching and cannot continue to run.
(II) Cause Analysis
1. Too Tight Installation: When installing the grate bars, if the installers do not reserve sufficient thermal expansion clearance, when the grate is heated and expands, the grate bars cannot extend freely and will squeeze each other, thereby generating an upward arching phenomenon.
2. Loose Chain: During long-term operation of the chain, due to reasons such as wear and stretching, it will become loose. When the chain is too loose, the tension of the chain during the operation of the grate is insufficient, and it cannot effectively restrain the grate bars, resulting in uneven gaps between the grate bars, which is prone to causing the grate to arch.
3. Abnormal Guide Rails: The guide rails on both sides of the grate are not straight and there are bending or deformation situations. During the operation of the grate, the frictional forces on both sides are uneven, which will generate a lateral force. When this lateral force reaches a certain extent, it will cause the grate to arch.
IV. Seizure and Stoppage of the Grate
(I) Fault Phenomenon During the operation process, the grate suddenly stops rotating. Although the motor is still running, the grate cannot continue to move forward, and the combustion process of the boiler is forced to be interrupted.
(II) Cause Analysis
1. Foreign Object Blockage: Foreign objects such as metal inclusions and hard stones are mixed in the coal. During the operation of the grate, these foreign objects will get stuck between the grate bars or between the grate and other components, hindering the normal rotation of the grate.
2. Component Damage: The grate bars break or the pins fall off, causing the grate bars to loosen and get stuck with each other. In addition, the tip of the slag stopper (eagle iron) sinks and contacts and gets stuck with the grate, which will also prevent the grate from operating normally.
3. Poor Lubrication: The sprocket bearings are lacking oil for a long time and are in a dry grinding state, which will cause the bearing temperature to rise sharply and the wear to intensify, making the sprocket rotation difficult, thereby affecting the normal operation of the grate and eventually causing the grate to seize.
4. Coking Issue: During the combustion process, if the coal quality is poor or the combustion conditions are not controlled properly, coking phenomenon is prone to occur. When the coking block is too large, it will increase the rotational resistance of the grate. Once the resistance exceeds the driving force of the grate, the grate will seize and stop. For more information related to boiler equipment, you can visit [the official website of Henan Hanyu Boiler Co., Ltd.](https://www.hanyuboiler.com/) to learn about it.
