Industrial centrifugal blower fan for fertilizer plant and cement plant introduction&operation manual

W4-68-No14C High temperature centrifugal blower

The W4-68-N014C high temperature resistant compound fertilizer centrifugal fan is used as the core equipment for dust removal in compound fertilizer factories and cement plants along with the bag filter dust collector.
It can be used to input gases and output gases, air and other non-spontaneous combustion and harmless to the human body. , Gases that are corrosive to steel materials. There is no viscous substance allowed in the gas, and the dust and hard particles contained should not exceed 150mg/m3. Gas temperature: no more than 300°C.
W4-68-N014C centrifugal fan is the earliest fan used in our country, but it is also the most common fan used in fertilizer production line, from high-rise buildings to underground railways, from boiler blasting to factory ventilation, W4 -68-N014C type fans can be found everywhere.

What are the types of fertilizer plant centrifugal blower fan?

Viewed from the side of the motor, if the impeller rotates clockwise, it is called a right-hand fan, represented by “right”; if the impeller rotates counterclockwise, it is called a left-hand fan, represented by “left”. The outlet position of the fan is expressed by the angle of the air outlet of the casing.
W4-68-N014C type fans №~6 are all made into one type when leaving the factory, and the user can install them in the required position according to the requirements. There is no need to specify when ordering. Among them, the position of the air outlet is adjusted. The range is 0~ 255, and the interval is 45 degrees; the air outlet positions of No. 16 and 20 are made into three fixed positions of 0, 90, and 180 degrees, which cannot be adjusted and must be specified when ordering.
There are four fan transmission modes: A, B, C, and D: among the 4-72 type fans, №~6 adopt A-type transmission, №8-12 adopt C and D-type transmission, and №16-20 adopt B-type transmission.

Compound fertilizer plant centrifugal blower technical parameter data table

Model	r/min	flow rate(m3/h)	pressure(Pa)	Power(Kw)
4-68-8D	1450	17585~30474	2158~1501	18.5
4-68-10D	1450	35420~61179	3442~2442	55
4-68-12.5D	960	45800~79111	2345~1657	55
4-68-8C	1800	21380~38300	3324~2353	37
4-68-10C	1250	30435~52684	2560~1954	37
4-68-12.5C	1120	3207~2256	53637~92274	75~90
4-68-16B	200	2964~2717	96052~165903	200
4-68-20B	710	138474~223947	3305~2342	220
4-68-12.5C	1120	53434~92295	3207~2256	75~90
4-68-16C	960	94738~165949	2846~2841	200
4-68-20C	710	138474~238464	3304~2374	220

What is the structure of a high temperature resistance centrifugal blower fan?

W4-68-N014C type high temperature resistancecentrifugal fan are mainly composed of impeller, casing, air inlet, motor and other parts. In addition to the above parts, №8~20 also has a transmission part.

Casing：

The casing of high tmeperature resistance centrifugal blower is welded with SS304 steel plate. L316 wear-resistant lining plates are welded to the inner walls of the casings of the introduction and exhaust fans for easy replacement after wear, and ribs are welded to the outside to enhance rigidity.
The shell of the large size fan is fixed on the foundation with a steel support. The casing and current collector are connected with bolts. The collector inlet can be equipped with an adjustment door. The casing is made into a split structure, and the rotor can be lifted out directly after the upper part is disassembled. The casing is provided with manholes for maintenance and inspection.

Impeller:

Impeller: It consists of 10 backward-inclined airfoil blades, a curved front disc and a flat rear disc. It is made of steel plate and has been corrected by dynamic and static balance. It has good air performance, high efficiency and smooth operation.
The impeller is plate type or wing type blades, welded with Q345 steel plate. For large-size, high-speed fans, WH60 or other high-strength alloy steel is used; the impeller works on the gas to obtain the required kinetic energy and static pressure energy.

Chassis:

Chassis: Made into two different types. Among them, the casings of Nos. 12 to 12 are made as a whole and cannot be disassembled. The casings of Nos. 16 to 20 are made of three-opening type. In addition to being divided into two halves along the middle horizontal plane, the upper part is divided into two halves vertically along the center line. Connect with bolts.
The collector adopts a hyperbolic trumpet shape, with the impeller inserted at the outlet, and a baffle structure welded on the outside to reduce the airflow return loss at the impeller inlet, thereby improving the fan efficiency; the main function is to accelerate the airflow concentration and reduce the flow loss so that the airflow can evenly fill the impeller.

Adjuesting door air inlet

The adjusting door adjusts the air volume by adjusting the opening of the blades. Adjust the direction of the door handle switch for the left-hand blower and the right-hand blower in the opposite direction. (The powder discharge fan does not have an adjustment door and can be ordered separately according to user requirements.)
Air inlet: Made as a whole, it is installed on one side of the fan. The cross-section parallel to the axial direction is a curved switch, which can make the air flow smoothly into the impeller with less loss.

Transmission:

The transmission part adopts D-type or F-type transmission mode, composed of main shaft, bearing box, flow bearing, pulley or coupling. The rolling bearing supports the operation and is directly connected to the motor with a pin coupling for driving. The bearing box is equipped with a thermometer and oil mark, and is lubricated with thin oil. The oil level should always be maintained within the oil level line. And using circulating water channel cooling, the water consumption is 0.5~1.5m3/h.

How to install a fertilizer plant centrifugal blower fan?

Before installation, you should first prepare installation materials and tools, and inspect all parts of the fan. The impeller, main shaft and bearings should be inspected particularly carefully. If any damage is found, it should be repaired and then the inside of the bearing box should be cleaned with kerosene. The following points must be noted during the installation operation:

On some joint surfaces, in order to prevent rust and reduce the difficulty of disassembly and assembly, some grease and mechanical oil should be applied.
When installing the bolts on the joint surface, if there are positioning pins, install the pins first and then tighten the bolts.
Check the inside of the casing and other casings. There should be no tools or debris left behind.

5 Installation steps of compound fertilizer high temperature fan:

Installation steps of compound fertilizer high temperature fan:
Rough positioning of the lower half of the casing.
The impeller and main bearing are leveled and aligned and then installed in place.
Leveling, alignment, and coaxiality adjustment of the motor and fan main shafts.
The casing, current collector, etc. are installed in place, and the remaining parts are installed.
When installing the adjusting door, attention should be paid to the blade opening direction being consistent with the impeller rotation direction.

8 Installation requirements of industrial blower fan:

When installing the fan, the weight of the gas pipeline should not be added to the casing. Pay attention to the size of the gap between the air inlet and the impeller, and Keep the shaft in a horizontal position.
When installing the air inlet duct, you can directly use the bolt connection of the air inlet itself. At this time, the air inlet is fixed by threeCountersunk head screws.
When the air outlet is installed at a certain angle, proper rotation of the back cover can keep the sign in a horizontal position.
When installing №8~12D fans, use a dial indicator and feeler gauge to measure the coaxiality of the fan main shaft and motor shaft and the coupling.The two end faces are not parallel. The tolerance for non-parallelism of two axes is. The tolerance of coupling end face non-parallelism is.
After the fan is installed, move the rotor by hand or lever to check whether there is any over-tightening or collision. If there is no such phenomenon, install the rotor can be tried.
After the motor is installed, install the pulley or coupling and guard. If the air inlet is not connected to the air inlet pipe, a protective net or other safety device (prepared by the user) must also be added. The power of the motor used in the fan refers to the power required under specific working conditions, plus mechanical losses and the required reserve capacity, and is not the power required when the air outlet is fully open.
If the outlet or inlet of the fan is not connected to the pipeline or is operated without external resistance, the motor is also in danger of burning. For safety reasons, a valve should be added to the outlet or inlet pipeline of the fan. It should be closed when starting the motor. After operation, the valve should be opened slowly until the specified working conditions are reached. Pay attention to whether the motor current exceeds the specified value.

Main bearing clearance adjustment of centrifugal fan blower

Due to the need for axial positioning of rotating systems such as the main shaft and impeller in the design, the fixed end of this type of fan is usually installed face-to-face with two single-row radial thrust ball bearings (i.e. angular contact bearings) between the inner rings of the two disc bearings. There is a spacer B, and the thickness of the gasket A determines the clearance of the two bearings.
The thickness of the gasket has been adjusted before leaving the factory. If the user stores it for too long or the gasket A is damaged during cleaning, it must be replaced according to the original thickness. Do not increase or decrease the thickness at will to avoid affecting the performance of the fan under normal operation of the machine.
The end of the main bearing seat of the fan close to the impeller (that is, the floating end) should be installed according to the drawing requirements. If the fan is used as an induced draft fan (when the medium temperature is high), attention should be paid to fully considering the thermal expansion space of the main shaft after it is heated and stretched.
If a self-aligning spherical roller bearing (3500 series or 3600 series) is selected as the bearing at this end, attention should also be paid to ensuring the necessary head clearance between the contact surface between the bearing outer ring and the seat body; if a plane roller bearing is selected as the bearing at this end , there is no such requirement.

How to adjust the industrial blower bearing top clearance:

Add paper pads of appropriate thickness (such as paper, insulation paper) to the bearing seat to adjust. The inspection method is to ensure that the feeler gauge of corresponding thickness (such as 0.03~0.06mm) in the range of 30mm~50mm at the top of the bearing can pass while the upper cover is pressed tightly.
The thermal expansion space in the radial direction of the main bearing should be ensured by adjusting the top clearance. That is to say, a gap of 0.03~0.06mm should be maintained within the top local range between the outer ring of the floating end main bearing and the seat body (depending on the size of the main bearing). upper and lower limits), its function is to ensure that when the main shaft is heated and elongated, the position of the main bearing in the bearing seat can smoothly move its axial position during the floating sliding process; and to ensure that there is local immersion between the outer ring of the main bearing and the seat body. Oil space, and the thermal expansion of the bearing outer ring at this time will not be “locked” by the seat body and cause excessive heating.
Pay attention to keeping the elastic position of the floating end bearing seat clean and smooth to ensure smooth sliding of the bearing; the presence of foreign matter is absolutely prohibited, and foreign matter such as drops of sealant, rust residue, and paint must not be left on the sliding surface, otherwise it will cause the main bearing to overheat. Wait for serious consequences. If the fan is used as a blower (or the medium temperature is low and only slightly higher than the ambient temperature), since the thermal expansion is small, the top clearance can be adjusted to a smaller value.

Routine maintenance of centrifugal blower fan

Fan maintenance personnel must pay attention to the following points:

The fan equipment can only be operated when it is completely normal.
If the fan adjustment equipment is started after maintenance, it is necessary to pay attention to whether all parts of the fan are normal.
Regularly remove dust, dirt, water and other impurities inside the fan and gas delivery pipes to prevent corrosion.
Cleaning of fan equipment is not allowed during operation.

Precautions during normal operation of the industrial fan

If it is found that the flow rate is too large and does not meet the usage requirements, or a smaller flow rate is required in a short period of time, the throttling device can be used to adjust it.
Regularly check the sensitivity of the thermometer and oil mark.
If any abnormality is found during the start-up, stop or operation of the fan, it should be inspected immediately.
For minor faults found during inspection, the cause should be promptly identified and efforts should be made to eliminate or deal with them. If the minor fault cannot be eliminated, or if a major fault is discovered, repairs should be carried out immediately.
In addition to changing the lubricating oil after each disassembly and repair, the lubricating oil should also be replaced regularly.

Common centrifugal blower fan failures and causes

1. Centrifugal fan bearing box vibrates violently

The fan shaft and the motor shaft are not concentric, and the coupling is installed crookedly.
The casing or air inlet is rubbing against the impeller.
The foundation is not rigid enough or not strong enough.
The impeller rivets are loose or the wheel disc is deformed.
The impeller disc and shaft are loose, and the coupling bolts are loose.
The connecting bolts between the casing and the bracket, the bearing box and the bracket, the bearing box cover and the seat, etc. are loose.
The air inlet and outlet ducts of the fan are poorly installed.
The rotor is unbalanced.
The pipe network is too thin and the wind speed is too fast.

2. Fan bearing temperature rise is too high

The bearing lubricating grease is of poor quality, deteriorates, and contains dust, sand, dirt and other impurities.
The tightening force of the connecting bolts of the bearing box cover and seat is too large or too small.
The shaft and rolling bearing are installed skewed, and the front and rear bearings are not concentric.
The rolling bearing is damaged.

3. Motor current is too large and temperature rise is too high

The gate or throttle valve in the intake pipe is not closed tightly when driving.
The flow rate exceeds the specified value or the air duct leaks.
The density of the gas delivered by the fan is too high, causing the pressure to be too high.
The motor input voltage is too low or the power supply is single-phase powered off.
The coupling connection is incorrect, the apron is too tight or the gap is uneven.
Affected by severe vibration of the bearing box.

Conclusion:

In this article, we introduce the high-temperature-resistant centrifugal blower used in the NPK compound fertilizer and cement industries. We cover the installation process in eight steps and troubleshooting techniques for when the fan malfunctions. Additionally, we provide guidance on selecting the appropriate type of centrifugal blower for your fertilizer plant. It’s important to note that the centrifugal blower is a component of the dedusting system and is typically used in conjunction with a bag filter. Below, we’ve included a link that explains how the fertilizer plant dedusting system operates and provides comprehensive information on the bag filter dust collector system.