What should be noted when selecting a motor for a Roots blower?

The three-phase asynchronous motor consists of two basic parts: the stator and the rotor. The stator is the fixed part of the motor, used to generate a rotating magnetic field, mainly composed of the stator core, stator winding, and base components. The rotor is the rotating part of the motor, made up of the rotor core, rotor winding, and rotor shaft, which functions to obtain torque under the action of the rotating magnetic field. The rotor is divided into squirrel-cage rotors and wound rotors based on its structure. The winding of the squirrel-cage rotor is cast together with bare conductors placed in the slots of the rotor core and the annular end rings at both ends, along with the fan blades. Rated working voltage, rated flow, rated speed, torque, etc., require an understanding of the motor's working conditions, operating conditions, installation methods, transmission methods, and motor structure. ① Pay attention to the reputation of the motor manufacturer; investigations have found that manufacturers with poor reputations should be approached with caution when purchasing. ② Pay attention to the quality of the motor; do not rush to purchase a motor before understanding the motor products. ③ Pay attention to the Price factor; generally speaking, you get what you pay for, and many merchants lure buyers with low prices, causing buyers many after-sales troubles; such sellers should be considered carefully.

2022-04-12

What is a Roots blower composed of?

The rotor of the Roots blower consists of an impeller and a shaft. The impeller can be divided into linear and spiral shapes, and the number of blades on the impeller is generally two or three. The rotation of the two-blade rotors inside the Roots blower casing relies on the synchronized transmission of torque through their respective gear meshing, so these gears are also called "synchronous gears." Synchronous gears serve both as transmission and as a positioning mechanism for the impeller. The structure of synchronous gears is relatively complex, consisting of a gear ring and a gear hub, positioned by a conical pin. Roots blowers typically use rolling bearings, which have advantages such as ease of maintenance and reduced axial dimensions of the blower, as well as convenient lubrication. The sealing areas of the Roots blower are mainly at the gap seal of the drive shaft extending out of the casing, which has a relatively simple structure, usually employing labyrinth seals or expansion ring seals. The oil seal for the bearings uses a skeleton rubber oil seal. The casing of the Roots blower can be either integral or horizontally split, with a simple structure. For large power gas blowers commonly used in chemical plants, such as gas blowers and absorption tower blowers, most adopt horizontally split blower casings that are convenient for maintenance and installation.

2022-04-07

The difference in functions between a Roots blower and a centrifugal blower.

They work differently; centrifugal fans use curved blades to throw gas to the casing through centrifugal force, while Roots blowers use two figure-eight shaped blades with a very small gap between them, relying on the compression of the two blades to push gas to the outlet. Due to their different working principles, they generally have different working pressures; the outlet pressure of Roots blowers is relatively high, while that of centrifugal fans is lower. The airflow is also different; Roots blowers are generally used in places where the airflow requirement is not high but the pressure requirement is relatively high, while centrifugal fans are used in places where the pressure requirement is low and the airflow requirement is large. The manufacturing precision is different; Roots blowers require high precision and strict assembly requirements, while centrifugal fans are relatively loose. Of course, there are some minor differences that I won't mention. Roots blowers are a type of high-pressure fan, and Roots blowers are positive displacement fans, where the airflow is proportional to the speed, transporting gas from the intake side to the discharge side. If the load requires a constant pressure effect, a centrifugal fan is used. This is because centrifugal fans are constant pressure fans, where the main working parameter is air pressure, and the output airflow varies with the pipeline and load, while the air pressure changes little. Centrifugal fans have low air pressure. The air compression process usually occurs through several working impellers (or stages) under the action of centrifugal force.

2022-04-06

What are the vacuum pumps of the Roots blower?

Under normal circumstances, the axes of the two rotors are installed horizontally, and the plane formed by the two rotor axes is in the horizontal direction. The air inlet of this type of pump is located above the pump, and the exhaust outlet is below the pump (the opposite is also possible). The lower exhaust outlet is usually connected horizontally, so the air inlet and exhaust directions are perpendicular to each other. One end is connected to the exhaust pipe, while the other end is either not powered or connected to a bypass valve. The characteristics of this structure are a low center of gravity and good stability during high-speed operation. There is also a vertical configuration: the axes of the two rotors are installed horizontally, but the plane formed by the two rotor axes is perpendicular to the horizontal plane. In this structure, the pump's inlet and outlet are set horizontally, which facilitates assembly and connection of pipes. However, its disadvantage is that the pump's center of gravity is too high, leading to poor stability during high-speed operation. The vertical shaft type: In some foreign Roots vacuum pumps, the axes of the two rotors are installed vertically to the horizontal plane. This structure allows for easy control of the assembly gap, convenient rotor assembly, and a small footprint, but the disassembly of transmission mechanisms such as gears is inconvenient, and the lubrication system is complex. Roots vacuum pumps with overflow valves: To prevent accidents caused by overload, Roots vacuum pumps are equipped with a more reliable safety protection device, which is an overflow valve installed on the bypass pipeline. When the pressure at the exhaust outlet exceeds the specified pressure, the valve of the overflow valve will automatically open to create an overflow. Once the exhaust outlet pressure returns to normal, the overflow valve will automatically close.

2022-04-02

How to solve the rusting of the blower?

When rotary blowers are used for a long time, various problems may arise, such as rust inside the machine. We can use small electric motors and pneumatic tools, such as angle grinders and polishers, to utilize their impact and sanding effects to remove rust and dirt. Sandblasting is a more thorough method of rust removal, capable of completely eliminating impurities and rust layers adhered to the metal surface. The surface treated by sandblasting provides good mechanical adhesion for coatings. Sandblasting methods include: dry sandblasting, warm sandblasting, closed dust-free sandblasting, throwing force method, and high-pressure water sandblasting. Chemical rust removal: This method is particularly suitable for processing workpieces with complex shapes and structures. It is important to note that the quality of the substrate itself and the construction requirements may vary. The metal is placed in an acid solution for washing, allowing the acid solution to chemically react with the metal surface oxides to achieve rust removal. It is recommended to use diesel for rust removal! The specific operation steps are as follows: If the Roots blower impeller is rusty, you can remove the blower outlet silencer, block the blower outlet, and pour kerosene from the inlet, which can soak about half of the blower chamber. After soaking in kerosene for a few hours, try to rotate it (you can use a flat pry bar inserted into the impeller gap to assist in rotation, being careful not to damage the impeller). If it can rotate, you can let the other impeller soak in kerosene for a few more hours, and you can wait until the next day to start running. Manual rust removal: Use tools such as diamond sandpaper, scrapers, hammers, and wire brushes to manually chisel and brush off the rust layer, and use cotton sandpaper to wipe away the rust dust before painting.

2022-03-31

What should be noted when disassembling and assembling a Roots blower?

First, we should pay attention to whether the disassembled parts of the equipment have any damage. If damage is found, repairs or replacements should be made. Next, the bearings should be cleaned thoroughly and lubricated. When installing the bearings, tools and hands should also be cleaned, and all dust from the mating surfaces should be completely removed before applying oil. If the sealing gasket is damaged or lost, it should be replaced with a gasket of the same thickness and material. During assembly, install the drive side wall panel (front wall panel) onto the casing. The impeller part is inserted into the casing from the gear end. Install the gear end wall panel onto the casing, paying attention to the axial total clearance; if insufficient, a casing sealing gasket can be selected. Assemble the front and rear bearings. When assembling the front bearing, the bearing housing should be filled with grease to 1/2-1/3 of the bearing space. Assemble the gears. Install the drive side bearing and locking nut together, and then install the bearing cover. Adjust the clearance and insert the positioning pin. Install the pulley and other components.

2022-03-29

Introduction to the principle of Roots blowers?

The three-lobe impeller performs three suction and exhaust cycles with each rotation, using two impellers. Compared to the two-lobe type, it has less gas pulsation, lower vibration, and reduced noise. Driven by the synchronous gear, air is transported from the fan inlet along the inner wall of the casing to the discharge side. The internal cavity of the fan does not require lubricating oil, has a simple structure, operates smoothly, maintains stable performance, and is suitable for various applications, having been widely used in many fields. The working principle of the Roots blower: when the motor drives the drive shaft to rotate through a coupling or pulley, the gear mounted on the driving wheel drives the gear on the driven wheel to rotate synchronously in opposite directions, causing the meshing rotors to rotate together, thereby forming a space between the casing and the rotor where gas enters through the inlet. The gas is compressed and expelled through the outlet by the rotor, while the other rotor rotates to a relative position with the first rotor where compression begins, forming a new space on the other side of the casing, allowing new gas to enter this space and be expelled, achieving continuous movement for the purpose of blowing.

2022-03-28

What are the differences between air compressors and Roots blowers?

Both can generate pressure and flow, but their uses are different; the Roots blower has low pressure but sufficient flow, so it is usually used in sewage or water treatment systems, and it is also used in some production lines, mainly for stirring, blowing, or suction. The Roots blower is used for delivering air, and it compresses and transports gas by utilizing three lobed rotors that move relative to each other within the cylinder, and it can also be used as a vacuum pump. The air compressor is short for "air compressor," which is used to generate compressed air and can produce high-pressure air. Air compressors are divided into two main categories: positive displacement and dynamic. Positive displacement is further divided into reciprocating and rotary types; dynamic can be divided into axial, centrifugal, and mixed flow types. Applications: Roots blowers are widely used in chemical, metallurgy, sewage treatment, aquaculture, light industry, mining, plastics, food, electricity, and papermaking, and can transport gases such as coal gas, natural gas, hydrogen, carbon monoxide, and acetylene using mechanical seals; selecting stainless steel impellers can transport corrosive toxic gases such as hydrogen chloride and hydrogen sulfide.

2022-03-26

What causes the heating of the Roots blower belt?

The belt of the Roots blower plays a pivotal role in the linkage between the motor and the blower. It is not uncommon for the blower's pulley to heat up during operation. So, what should be done if the Roots blower belt heats up? Typically, the heating of the Roots blower belt is generally caused by the belt being too loose, overloaded, or reaching the end of its lifespan. Manufacturers should adjust the blower's belt to the appropriate tension before leaving the factory to ensure smooth operation. A belt that is too loose not only causes heating but also wears out the belt, leading to high temperatures in the pulley. If the belt is too tight, it can also cause heating. This not only affects the linkage of the blower but also results in losses during power transmission. An overly tight belt may even break during operation. Therefore, both loose and tight belts are undesirable. Manufacturers should conduct strict testing of all indicators of the blower before leaving the factory to ensure good operation. The heating of the Roots blower belt is more severe in summer. Some customers pour water on the belt, which can lower the temperature of the belt, but it severely affects the fit between the belt and the pulley, reducing friction and leading to insufficient power transmission and slippage. If water accidentally flows into the blower, it can cause rust on the internal impeller, which over time can lead to seizing and damage to the Roots blower.

2022-03-25

How can we reduce the noise of a Roots blower? What is the solution?

In fact, it is normal for Roots blowers to produce noise during daily operation. As long as there is no abnormal change in sound, there is no need to worry. If a quiet working environment is required, some soundproofing devices can be used. The mechanism of noise generation in Roots blowers is due to the presence of different noise sources within the fan, but the locations of generation are different, including: first, aerodynamic noise at the inlet and outlet; second, radiated noise from the mechanical chassis and engine; (3) basic sound radiation from solid sounds. Among these noise sources, the aerodynamic noise emitted from the input and output points (referred to as aerodynamic noise) is the strongest, while mechanical noise and other noises such as electromagnetic noise are secondary factors in the normal operation of the fan. Analyzing the frequency spectrum of the noise generated by the Roots fan reveals that its characteristic is low bandwidth. Aerodynamic fan noise is mainly composed of two parts: rotational noise and vortex noise. To eliminate some noise, one can choose to install a silencer at the exhaust port of the Roots blower, which has built-in sound-absorbing inserts. Alternatively, adding a soundproof cover to the Roots blower can not only solve the noise from the casing and motor but also provide overall vibration isolation for the fan base.

2022-03-21