Fault of fan impeller and its treatment measures:
The fan impeller will inevitably appear various corrosion and wear after a long time of operation. Generally, it is divided into: impeller corrosion, impeller wear, adhesion of impeller dust and impeller high-temperature gas. Explain in detail the treatment measures for various damages:
1. Corrosion treatment measures
The corrosion of fans is common. It is not only produced in the fans conveying CO2 gas, * – * and other corrosive gases, but also in the fans dealing with the atmosphere containing various exhaust gases, which will also produce unpredictable corrosion at any time.
The treatment measures to be taken when the impeller is corroded are as follows:
(1) Re analyze the composition of the gas medium and the materials used.
(2) CO2 gas and * – * have almost no corrosion resistant materials except in dry state. Therefore, check the poor operation of mixed water and take treatment measures.
(3) Check the falling off of coating materials for anti-corrosion.
The types of coating materials include thin stainless steel plate, metal coating materials composed of liquid metal spraying and metal spraying, as well as non-metallic coating materials composed of coatings, rubber, vinyl resin, etc.
When the rotor is unbalanced and causes excessive vibration due to corrosion, ordinary steel is often used for emergency repair. However, since the impeller of the fan is a rotating body, it needs to be replaced with wear-resistant and corrosion-resistant metal material as the coating material as soon as possible.
2. Wear treatment measures
When the impeller of the fan for conveying powder is seriously worn, it shall be regarded as a vulnerable part.
For example: exhaust fans for combustion furnaces in iron and steel plants, various exhaust fans for cement plants and fans for conveying various powders.
In addition, the boiler exhaust fan also gradually belongs to the model that needs to take anti-wear measures.
In order to reduce wear, measures such as reducing the amount of dust or optimizing the form of impeller need to be taken, but the method of reducing the circumferential speed of impeller is the most effective way.
As a way to prolong the service life of worn parts, the following wear-resistant measures can be taken:
(1) Made into a leaf with a fish scale.
(2) Hard chromium plating or hard metal spraying.
(3) Hardfacing with hard electrode.
(4) Install the lining plate (which can be replaced after wear).
The above measures are all methods to prolong the service life of the impeller.
During regular maintenance, * – * regularly check the wear condition, so as to prepare for repair in advance.
3. Dust adhesion treatment measures
Because the dust in the gas will adhere to the blades, it is bound to hinder the air flow, reduce the air volume, reduce the efficiency, or cause excessive vibration due to the uneven falling off of attachments and attachments.
The treatment measures include:
(1) Select the blade form that is difficult to attach dust, such as backward blade.
(2) Take measures to remove attachments.
The methods of removing attachments are as follows:
(1) Wash with water regularly and intermittently.
(2) The mechanical removal device can partially remove the attachments.
(3) By blowing hot air and cold air to form a temperature difference.
(4) Method of injecting powder particles.
In short, in today’s energy-saving era, it is valuable to make some efforts to maximize the long-term operation under high efficiency conditions.
4. High temperature gas treatment measures
When the medium is high-temperature gas, it can be solved by selecting heat-resistant materials.
Since most of the high-temperature gases are combustion exhaust, the accidents caused by corrosion and wear are in the majority.
There are also a few accidents due to the poor operation of the equipment, resulting in a sharp rise in the temperature of the gas medium, resulting in the deformation of the impeller which is difficult to use for a long time due to creep, as well as the condensation due to temperature drop, resulting in increased corrosion.
Considering the obvious creep phenomenon of carbon steel near 400 ℃, in order to prolong the service life of the fan, full efforts should be made in the operation range and operation management.