5. Improve the Centrifugal Fan Structure by Xianrun Blower

5.1 Optimizing Air Inlet of Centrifugal Fan

Starting from the motion law of gas-solid two-phase flow, analyzing the dust particles movement and wear mechanism, changing the trajectories of particles from the pneumatic perspective, are a effective measures to improve centrifugal fan wear.

centrifugal fan air intake by xianrun blower

Selecting reasonable fan air inlet is to improve the fan inlet condition and dust air flow movement mode, so as to reducing centrifugal wear. Practice has proved that the centrifugal fan will have serious uneven wear when using common cylindrical inlet; when the air inlet is modified to horn type inlet, will improve blade wear.

centrifugal fan air inlet by xianrun blower

4.5 Sticking wear resistant ceramic chips to blade surface by Xianrun Blower

4. Improve the centrifugal fan blade wear resistance in cement plant

Ceramic material have the features of high wear resistance, high corrosion resistance, low density, low coefficient of friction, and high hardness. 

When the angle of attack is small, compared with metal and rubber, the ceramic wear is the smallest. 

xianrun blower ceramic chips on blade surface

Sticking ceramic material to fan blade surface, 1.5 mm ceramic chips on easy to wear place on centrifugal fan impeller, is a very effective way to improve the wear resistance of the blade. 

What is more,the small ceramic chip thickness won't increase impeller quality much, so sticking wear resistant ceramic chips will not affect the impeller design strength and fan moment of inertia of startup.

It is worth noting that the expansion of the ceramic material and steel material difference is big, so the centrifugal fan working temperature should not be too high; must ensure adhesive combined strength, and prevent wear-resisting ceramics chips fall off during the working; ensure the blade surface is smooth without spray coating.

wear resisting ceramic chips by xianrun blower

4.4 Wear resistance lining board in fan impeller by Xianrun Blower

4. Improve the centrifugal fan blade wear resistance in cement plant

Overlaying wear resistant lining board and wear resisting layer in abrasion area can prevent the blade wearing. Generally, it is better to add 16 Mn low alloy liner on blade working surface, non-working surface, blade head. 

Because of working surface serious wear, overlaying wearing layer on lining board is a good measures to improve the wear resistance.

wear resisting centrifugal fan impeller by xianrun blower

Overlaying strip wear-resisting layer by wear-resisting welding wire on the blade working surface; surfacing 3 ~ 5 mm wear-resisting layer on the blade head. The non-working surface wear is not serious, so only lining board is OK. 

The shape of wear resisting lining board should be the same as impeller blade,so as to avoid welding stress during assembly.

Before welding wear-resisting layer, rust cleaning, preheating treatment are necessary to lining board, and the welding wire need drying, in order to prevent cracks, porosity and other defects in wear resisting layer.

wear resisting lining board in fan impeller by xianrun blower

4.2 Blade surface protection treatment & 4.3 Wear resisting cutting edge by Xianrun Blower

4.2 Blade surface protection treatment

Wear-resisting surfacing alloy process in centrifugal fan blade form a hard and wear resistant protective layer on the blade surface, which can improve the fan blade wear resistance. Actual welding wearing layer thickness and position are decided by blade thickness, wear condition and welding technology.

Xianrun Blower high pressure fan impeller

4.3 Wear resisting cutting edge in centrifugal fan impeller

In general, fan blade head has serious wear, so it is essential to improve the wear resisting performance of the blade head. The sinter cemented carbide anti-wear leading edge composed by cemented carbide is an effective measure.
In order to have a good aerodynamic performance, the appearance of the blade leading edge should be made accurately, and the wear-resistant cutting edge can use diffusion combined with electron beam welding technology.

xianrun blower wear resisting fan impeller

4. Centrifugal fan wear proof measures in cement plant by Xianrun Blower

4. Improve the centrifugal fan blade wear resistance

4.1 Wear resisting blocks on blade surface 

The basic movement of dust particles in the wear parts is sliding or rolling along the blade surface, and cause a certain pressure to blade surface. Using wear-resisting 
welding wire builds up welding wear-resisting horizontal stripes along the axial in blade working surface, forming wear-resisting layer. 

wear resistant centrifugal fan impeller by Xianrun Blower

This wear-resisting layer can block dust particles movement; change the movement direction,so that the dust particles will jump away from the blade surface; the wear resisting blocks form a protective layer in blade working surface, then prolong the centrifugal fan service life 1 ~ 2 times.

The diplarthrous prominent blocks welded on the blade surface, also can have wear resisting function. After welding small wear resisting blocks, the centrifugal fan impeller should be corrected with dynamic balance and static balance correction, to ensure the smooth working. Small centrifugal fan can only be corrected with static balance.

Xianrun Blower wear resistant centrifugal fan wheel

centrifugal blower wheel welding in Xianrun Blower factory

Centrifugal fan wear proof measures in cement plant by Xianrun Blower

3. Choose Suitable Wear Resistant Fan 

Different models fans have different wear-resisting degree. Generally, large centrifugal fan with low speed have better abrasion resistance. Compared with axial flow fan, centrifugal fan usually can provide the abrasion resistance of 4 ~ 5 times.

wear resistant centrifugal blower by xianrun blower

The casings of wear resistant fan are welded by steel plate; lining of casing have guard board, in order to replace after serious wear.

What is more, fan speed also have important influence to centrifugal fan wear, the higher speed, the more serious wear. Under the premise of meet the requirements of air flow and pressure, low speed centrifugal fan can reduce wear and tear. 

large capacity centrifugal blower by xianrun blower

If the centrifugal fan works in air dust, it is better to choose wear-resistant fans with low speed. 

large airflow centrifugal fan for cement plant by xianrun blower

Centrifugal fan wear proof measures in cement plant by Xianrun Blower

2. Control operating point reasonably

The change of the fan operation condition has a great influence for gas-solid two-phase flow inside the impeller. 

Centrifugal fan in cement plant by xianrun blower

When airflow deviates from the designing flow of the fan, the particle trajectory in the centrifugal fan will change, and the impact position of dust particles on the plate cover and blades will move move back and forth, so that wear changes accordingly.

In general, when the actual flow skews to small airflow, it benefits to decrease the impeller wear. When the deviation is serious for the design point, it will increase the fan wear. Therefore, it needs to optimize and control the operating point reasonably.

high pressure centrifugal fan in cement plant by xianrun blower 

For the general centrifugal fan, when the minimum flow is equal to 80% of design flow rate, it benefits to decrease fan wear.

centrifugal fan in cement plant

Centrifugal fan wear proof measures in cement plant by Xianrun Blower

1.Improve the effect of dust removal system

Dust particles in the flue gas is the root cause of fan wear, so improving the efficiency of dust removal equipment, reducing the dust concentration, are the most effective way to 
prevent fan wear. 

dust removal system in cement plant

As for the dust produce equipment and dust production points, it needs to set up high efficiency dust removal system, and the centrifugal fan should be equipped with dirt purification equipment. 

In the dust removal system, the centrifugal fans are generally installed after the dust removal equipment, to ensure that the fans works under purified air, eliminating the wear conditions.

In conditions allow,the dust removal equipment efficiency should be as high as possible, to increase gas purification rate. For the dust removal equipment, it is better to make regular maintenance and inspection according to their structural characteristics, to ensure their normal working conditions.

dust removal system in cement plant by xianrun blower

Centrifugal fan wear causes in cement plant by Xianrun Blower

Centrifugal fan is an important auxiliary equipment in cement production. 

In general, they are gas-solid two phase flow centrifugal fan in cement industry, such as ID fan of dust removal system, FD fan of pneumatic conveying system. This is to say, the working medium of this centrifugal fan often contains a certain amount sizes and shapes of solid particles. 

customized heavy duty industry fans for cement plant by xianrun blower

Because the centrifugal fan works under dusty gas flow, the dust particle in air flow not only cause wear and tear on the fan impeller, but also adhere and gather ash deposition. What is more, the wear and ash deposition are uneven, destroying the fan rotor balance; causing centrifugal fan vibration; reducing the service life. In that case, the centrifugal fan can not work normally.  

industrial fans in cement plant by xianrun blower

Especially after the serious wear of fan blade, it will destroy the flow characteristics inside the fan, as well as easy to cause major accident, such as blade fracture and coasters.

So, it is necessary to take corresponding measures to impeller wear in cement industry.

double suction centrifugal fan in cement plant

Cupola Blower and Dust Collecting Fan in Metallurgical Industry---By Xianrun Blower

Converter Secondary Flue Gas Dust Collecting Fan
Converter secondary flue gas dedusting system is dust collection and dust removal of flying dust-forming points, apart from converter smoke purification and gas recovery. 
In this flue gas dust removal system, the centrifugal fans are used in bessemerize, melted iron, argon flushing station, molten iron slag skimmer system, down tank standing and so on. 

dust collecting blower by xianrun blower

Cupola Blower
Centrifugal blower are necessary in iron and steel smelting process, what is more, cupola furnace (such as oil furnace, pulverized coal furnace) in machinery casting factory, 
also need centrifugal blower (high pressure fan, large airflow blower and so on) to send enough combustion air. 

cupola blower by xianrun blower

xianrun industrial fans in steel industry

Blast Furnace Blower in Metallurgical Industry---by Xianrun Blower

In the process of pig iron smelting, it needs to use the blast furnace blower transport combustion-supporting air (oxygen) to blast furnace, in order to improve the blast furnace temperature.In addition,centrifugal blower also need to send combustion air to the hot blast stove. 

blast furnace blower in metallurgical industry by xianrun blower

Oxygen play an important role in iron and steel industry, such as strengthening smelting process. In steelmaking process, oxygen is used to top-blown converter, and bottom blowing converter.  

Open hearth furnace molten pool oxygen furnace steel, electric furnace oxygen steelmaking, etc. Especially the oxygen top-blown converter steelmaking has become a 
major skills in iron and steel industry development.
Oxygen demand is very high in steelmaking, and they are obtained from air by air separation equipment. 

In general, air compressor, oxygen compressor, centrifugal blower and turbine expander are required in steel manufacture. 

blast furnace blower in metallurgical industry by xianrun blower

Coke oven gas centrifugal fan in metallurgical industry---by xianrun blower

Coke is a major fuel and reducing agent for iron and steel smelting. What is more, it is also proppant and bulking agent for blast furnace.  
The coal oven gas in coke oven after centrifugal fan extraction, part as fuel for coke oven; part as fuel for steel plant after forcing, and the other part as secondary product. 

coke oven gas centrifugal fan in metallurgical industry by xianrun blower

This model centrifugal fan are mainly composed of blower, motor, gearincreaser, lubrication system, I&C system. 
Casing is horizontal split structure; transverse longitudinal location keyway under bearing box is to keep the blower in the centering position, and fit casing thermal expansion; bearing box and shell are cast in block, the stiffness is suitable to maintenance. 

Coke oven gas centrifugal fan in metallurgical industry by xianrun blower

The rotor consists of main shaft, three impeller, spacer bush, the balance disc and half couplings, etc; impeller is welded by high strength alloy steel. Bearing is divided into two parts, support bearing and thrust bearing. 

grain depot ventilation fan by xianrun blower

Wear resistance measures of sintering fan----by xianrun blower

Sintering draught fan is the main suction machine of sintering machine, takes on 50% total power consumption in sintering plant. And the dust content of ore sintering flue gas is big. In this case, improving efficiency, reducing energy consumption, strengthening the wear-resisting, prolonging service life are main technological skills for sintering fan. 

Sintering draught fan by xianrun blower

Wear resistance measures of sintering fan

(1) Zigzag central disk can not only improve the outlet air distribution, but also avoid scour of flue gas to the central disk;
(2) Replaceable wearing plate mounted on the blade;
(3) Replaceable cone plate protect the central disk from the wear and tear;
(4) The casing is equipped with scroll plate and side plate;
(5) Impeller is coated with ceramic wear, resin, quartz powder with water glass and so on;
(6) Impeller surface is treated with strengthening processing, such as the surface welding, thermal spraying, boriding, laser surface hardening and high frequency quenching, etc.

Wear resistance measures of sintering fan by xianrun blower

The application of centrifugal fan in metallurgical industry--by Xianrun Blower

The centrifugal fan plays an important role in the smelting process of iron, steel and other metal materials. From ore to steel, it needs to through the smelting process of ore sintering,iron-making and steel-making. All these technological processes need centrifugal fans or axial flow fan. 

double suction centrifugal fan

Sintering fan

Sintering machine sinters ore before smelting, and sintering furnace needs smoke exhaust fan and cooling ventilation fan. 

For example, a medium type steel plant has two ore sintering workshops. One workshop with 5 units 62.5 ㎡ sintering machine, needs 29 sets fans totally, while 18 sets are used in sintering machine; 

the other workshop with 3 units 75 ㎡ sintering machine, needs 90 sets fans totally, while 18 sets are used in sintering machine. Other fans are used to ventilation, dust removal, cooling and cooling.

centrifugal fan in steel plant

About dozens of models centrifugal fan are used to exhaust ore sintering flue gas in this process. 

The application of centrifugal fan in power plant---by xianrun blower

Main introduction (Xianrun Blower)

In power plant, fans and blowers are widely used in air-flue gas system and pulverizing system of power plant, to convey air, smoke, coal air mixture. The fans are ID fan, FD fan, primary air fan, return fan.

xianrun blower in power plant

In the pulverized coal-fired boiler, ID fans are used to induced smoke, to ensure the negative pressure in the boiler; FD fans supply air flow to fuel combustion; 
primary air fan carry pulverized coal to inner boiler, and supply air flow to primeval combustion. 

In wet FGD (Flue Gas Desulfurization) system, booster fan improve the flue gas pressure, to go through desulfurization tower. 

In circulating fluidized bed boiler, fluidization fan fluidize the returned bed material. 

There are also many small blower to be used for cooling, sealing, ventilation. 

Centrifugal fan category

1. Air pressure is less than 17400 N/㎡, and the centrifugal fan are widely used as ID fan, FD fan for boilers, tunnel and duct ventilation. 
2. Air pressure is between 17400 N/㎡ ~ 34300 N/㎡,and the centrifugal fans convey coal gas, SO2, mixed gas and so on. 
3. Air pressure is more than 34300 N/㎡, the centrifugal fans convey CO2, catalytic gas and other chemical gas. 

xianrun blower widely application

Conclusion 

In the coal-fired power plant, centrifugal fan with Variable Frequency Control have fewer shake and electric current, in this case, the centrifugal fan is safer and more power saving. 

The mainly application of centrifugal blower and axial flow fan

Xianrun blower and fan can be used at any situation related to air or smoke ventilation, whether in general situation or special industrial project. 

application of centrifugal fan

(1) General air cooling , heat dissipation, air ventilation for large place, such as gym, underground parking, grain depot, warehouse, etc. 

(2) Boiler forced draft fan (FD), high temperature induced raft fan (ID Fan), used in energy power plant, types boiler, brick plant kiln, cement kiln, rotary kiln, garbage incinerator, steel processing plant. 

(3) Dust collecting for bag filter, cement plant, power plant, steel plant. 

(4) Corrosive gas delivery, and particle material/ powder material/ fragment materials/fiber materials, such as chemical factory, textile mill factory. 

applications of industrial fans and blowers

High capacity centrifugal fan casing---by Xianrun Blower

Notes during the centrifugal fan operation

Matters need attention during the fan working---by Xianrun Blower

cement plant centrifugal fan

1. If the air flow is too big to conform to the requirements, or need smaller flow in a short period of time, all these can be adjusted by throttling gear. 

2. Check the thermometer and oil sensitivity regularly, and control bearing box oil level within allowable scope. 

3. Check immediately for any abnormal phenomenon during the centrifugal fan running or stop. 

4. For the small fault, find out the reason, try to eliminate or processing in time; if the small fault can not be eliminated, or find out big failure, should be checked immediately.

5. Lubricating oil should be changed after repairing, and lubricating oil also should be changed regularly. 

6. Check bearing pedestal of E mode driving regularly (quarterly), cleaning and adding lubricating oil, in case of bearing burning out.

E mode driving mode centrifugal fan

Why air pressure increase, air flow decrease during centrifugal fan working?

Reasons (Xianrun blower)
1. The gas composition changes, or air temperature is too low, or solid impurity increase, all these increase air density. 
2. Air outlet pipe or valves are blocked by dust, soot, or other sundries. 
3. Air inlet pipe, valves, screen are blocked by dust, soot, or other sundries. 
4. Air outlet pipe fracture, or pipe flange sealing is not tight. 
5. Sealing rings have serious damage, or centrifugal fan blade have abrasion. 

coupling driving centrifugal blower

Solutions
1. Check the air density and work out the reasons. 
2. Turn up air outlet valves, or make clean. 
3. Turn up air inlet valves, or make clean.
4. Weld the fracture, or change duct flange gasket. 
5. Change the sealing rings, fan impeller. 

coupling driving centrifugal fan

Fault Diagnosis of Centrifugal Fan--Part 2 High Bearing Temperature

There are 3 reasons to cause abnormal temperature rising for centrifugal fan bearing, such as poor lubrication, insufficient cooling, abnormal bearing.  

If the bearing temperature rising by bearing fatigue wear, such as dehull, pockmark, gap increasing, it can be judged by listening bearing sound and testing vibration. 

coupling drive centrifugal fan of xianrun blower

(1) Poor lubrication. It needs to oil bearing box regularly. Oiling too much can also cause bearing temperature rising. In this case, bearing temperature rises continuously,then the temperature will remain unchanged after reaching to certain point (generally higher than the normal operating temperature around 10 degree centigrade to 15 degree centigrade), finally the bearing temperature will decline gradually. (xianrun blower)

(2) Insufficient cooling.Too small cooling fan will cause insufficient cooling air volume. Bearing box does not get effective cooling, so the bearing temperature rises.

(3) Check the bearing box again after eliminate the above problems.

high pressure coupling centrifugal fan of xianrun blower

Fault Diagnosis of Centrifugal Fan--Part 1 Fan Bearing Over-standard Vibration

Fault Diagnosis of Centrifugal Fan--Part 1 Fan Bearing Over-standard Vibration 

 ---by Xianrun Blower 

The fan bearing vibration is the most common problem during the working, because it causes bearing and blade damage, bolts looseness, casing and duct system breakdown. 

centrifugal fan main shaft

1.1 Dust deposition 

When air enters the impeller, and rotating blades surface have angle. According to the fluid mechanics principle, the non-working face of blade leaves a vortex, so dust will deposit
slowly under the effect of vortex. The rotating impeller will throw out a part of dust when the dust reaches a certain weight. 
As a result, uneven dust in impeller blade causes impeller unbalanced, then make the fan over-standard vibration.


1.2  Duct system vibration

Smoke or air duct system vibration lead to centrifugal fan forced vibration. And the vibration usually cause fan outlet enlarge; the air volume increas; the vibration changes.
On the other hand, uneven incoming air area of fan inlet, such as not unified baffle opening and closing, can also cause impeller vibration.

centrifugal blower in cement plant

1.3 Collision of dynamic and static parts

(1) the fan impeller and air inlet are not on the same axis. 
(2) air inlet  has damage and deformation. 
(3) impeller looseness increases impeller waggle. 
(4) bearing failure. 
(5) the connection between shaft and bearing become loose. 
(6) main shaft distortion. 

centrifugal fan in cement plant

centrifugal fan casing production

The structural features of inlet box and casing

Fan maintenance is a skill what technical personnel must master, and it is necessary to understand the whole structural features of centrifugal fan. 

As for the high capacity centrifugal fan with double supporting, inlet box is necessary. 

double suction industrial centrifugal fan

Inlet end of inlet box is connected to the air duct system; the intermediate shaft of inlet box is placed in the intermediate shaft enclosure;  
the half coupling of motor side is protected by coupling guard; the whole inlet box is fixed on the foundation.In order to reduce the fan noise,inlet box can be equipped with silencer. 

high capacity centrifugal fan

The fan casing is welded structure, the upper cover of fan casing can be removed, for the convenient to disassembling and maintenance of the impeller. 

Main bearing box supporting impeller is linked with the second half of the cover by bolts, and centring through the flange. 

double suction centrifugal fan