Mingfeng Machinery explains the principle of the Roots blower.

Roots blowers belong to positive displacement rotary blowers, with the main power sources being electric motors, diesel engines, or a combination of both. The main parameters for selection include air volume, pressure, speed, and motor power. A typical three-lobe Roots blower mainly consists of two parts: the drive motor and the blower head. The drive motor is the power source for the blower, which can be either an electric motor or a diesel engine, while the blower head is the main working component of the Roots blower. It operates in a regular manner to achieve the purpose of gas transportation. To understand the working principle of the Roots blower, one must have a thorough understanding of the structure of the blower head. The main components of the blower head include: wall plates, casing, driving impeller, driven impeller, driving and driven gears, main and auxiliary oil tanks, bearings, etc. The Roots blower has two impellers that rotate in opposite directions under the drive of the motor. When the impellers pass the intake port, a sealed chamber is formed between the two impellers and the wall plates and casing. As the impellers continue to rotate, the air inside the sealed chamber is compressed and expelled through the exhaust port. This process repeats, transporting external air to the destination through the intake and exhaust ports. There are certain gaps between the impellers, between the impeller and the wall plates, and between the impeller and the casing. These gaps have fixed standards and tolerances; if the tolerances are too large, it can lead to other corresponding failure issues. When the impeller passes the exhaust port, under the pressure in front of the pipeline, some gas will leak to the outside through the gaps. This type of leakage is referred to as internal leakage. Since the Roots blower is a positive displacement blower, once it starts operating, the air volume will not change significantly. Even with slight changes in front pressure, it can continue to transport air. After long-term use, the air volume of the Roots blower may change, usually decreasing. The main reasons for this are changes in the gaps between the impellers, between the impeller and the wall plates, and between the impeller and the casing, which increase internal leakage and subsequently affect the air volume of the Roots blower. To ensure the normal operation of the Roots blower, other components of the blower also play a very important role, such as bearings and gears. If the cooperating components experience abnormal failures, it will also greatly impact the operation of the blower. Therefore, in later maintenance, not only should important components be meticulously maintained, but other cooperating components should also be regularly serviced!

2022-06-22

Precautions for Overloading the Motor of the Tri-lobe Roots Blower

(1) The three-lobe rotary blower has a large pressure difference compared to the specified pressure, meaning the back pressure or inlet pressure is high; (2) Compared to the required flow rate of the equipment, the blower's flow rate is too high, resulting in increased pressure; (3) Inlet filter blockage, outlet pipeline obstruction or blockage; (4) Rotating parts collide and rub (jam); (5) Oil level too high; (6) The narrow V-belt of the three-lobe rotary blower overheats, vibrates excessively, and the pulley is too small. (1) Reduce the pressure to the specified value; (2) Release excess gas into the atmosphere or reduce the blower speed; (3) Remove obstacles; (4) Immediately stop the machine and check the cause; (5) Adjust the oil level to the correct position; (6) Check the belt tension and replace it with a larger diameter pulley.

2022-06-20

Mingfeng Machinery shares the reasons for the tripping of the Roots blower frequency converter.

1. Thunderstorms and heavy rain, or the startup of large equipment, can cause fluctuations in the power grid voltage, which may lead to the frequency converter's undervoltage protection tripping. 2. Due to long periods of neglect in maintenance and cleaning, excessive dust accumulation on the internal boards of the frequency converter or on the heat sink reduces the machine's cooling efficiency, causing the frequency converter to trip due to protective measures. 3. Excessive dust and debris accumulation inside the Roots blower, if not cleaned in time, reduces the gaps between rotors and between the rotor and the chamber, thereby increasing load resistance, which causes the motor and frequency converter to overload and trip protection. 4. When selecting a frequency converter, the chosen model capacity is too small. Generally, the capacity of the frequency converter should be about 20% larger than the rated power of the motor to ensure that the frequency converter can still drive the motor when it reaches full load. 5. Power supply voltage that is too high or too low can cause the frequency converter to overheat and trip protection. A power supply voltage exceeding 410 volts will increase the internal heat generation of the frequency converter, leading to a trip. A power supply voltage below 360 volts will increase the working current of the frequency converter, resulting in an overcurrent protection trip. 6. Issues with the frequency converter itself, such as damage to one of the rectifier templates on the back of the frequency converter, can cause the other two to operate in an overcurrent state, leading to a trip. If the Roots blower does not start under no load, it will trip or stall; it is essential to remember that the Roots blower must start under no load. A simple trip of the Roots blower will not damage it; in this case, one should open the vent valve, start the blower, and check its operating condition. If the motor burns out and cannot start the Roots blower, we will need to replace the motor, which is a significant loss. The Roots blower cannot be pressurized; pressurization can easily lead to motor damage, and a sudden increase in pressure on the blower can lead to severe situations. Unstable voltage is also one of the reasons for the protective power-off trip of the aeration Roots blower frequency converter. If the voltage is too low, below 360 volts, it will cause the aeration Roots blower to trip due to overcurrent protection; conversely, if it exceeds 410 volts, it will cause overheating inside the frequency converter and trip protection. When large equipment around the application scenario of the Roots blower causes significant voltage fluctuations, it can also lead to the blower's power-off protection trip. If there is a fault in one of the rectifier templates of the aeration Roots blower frequency converter, it will cause an overcurrent protection trip. Do not allow excessive dust accumulation inside the aeration Roots blower frequency converter or heat sink, as this will hinder cooling and cause the Roots blower to trip. If long-term rust and dust cause the gaps inside the Roots blower rotor, chamber, etc., to decrease, resistance will increase, leading to overload and power-off protection. 1. Startup precautions: If the Roots blower does not start under no load, it will trip or stall; it is essential to remember that the Roots blower must start under no load. 2. Simple trip: A simple trip of the Roots blower will not damage it; in this case, one should open the vent valve, start the blower, and check its operating condition. 3. Motor burn-out: If the motor burns out and cannot start the three-lobe Roots blower, we will need to replace the motor, which is a significant loss. The Roots blower cannot be pressurized; pressurization can easily lead to motor damage, and a sudden increase in pressure on the blower can lead to severe situations.

2022-06-16

Do you know the main reasons for the wear of the impeller in a three-lobe rotary blower?

There are many reasons for wear, so wear is very complex. But what are the reasons for the wear of the three-lobe Roots blower impeller? 1. Fatigue wear = surface fatigue stress (or temperature or impact) leads to surface cracks and flaking. 2. Abrasive wear = due to the filing effect of solid particles dispersed between interfaces under relative motion and wear, resulting in concave surfaces and uneven contact surfaces. It has a significant impact on the degree of wear of the impeller. In the three-lobe Roots blower, solid particles and the surface of parts move relative to each other at a relatively fast speed, causing wear. 3. Erosion wear = surface scratches formed by solid particles cleaning the metal surface. 4. Adsorption wear = if other conditions are the same, improving processing accuracy and surface cleanliness does not reduce wear. On the contrary, because the interface is tight, the molecular adsorption function is large, and interface wear increases. This is adsorption wear.

2022-06-14

Installation precautions for the safety valve of a three-lobe rotary blower

The safety valve of the three-lobe rotary blower should be installed upright and close to the protected equipment or pipeline. If it cannot be arranged close by, the total pressure drop from the protected equipment or pipeline to the safety valve inlet should not exceed 3% of the safety valve set pressure. A maintenance platform should be set up for the safety valve of the three-lobe rotary blower. When arranging heavy safety valves, consider the possibility of hoisting after disassembly, and a lifting rod should be provided if necessary. The inlet pipeline of the safety valve of the three-lobe rotary blower should use long-radius elbows. The design of the outlet pipeline of the safety valve of the three-lobe rotary blower should consider that the back pressure does not exceed a certain value of the safety valve set pressure. For ordinary spring-type safety valves, the back pressure should not exceed 10% of the safety valve set pressure. When the medium discharged into the venting main pipe or the flare main pipe contains condensate or condensable gases, the outlet of the safety valve should be higher than the main pipe; otherwise, liquid drainage measures should be taken. The outlet pipeline of the safety valve discharging into a closed system should be connected at a 45° angle to the top of the discharge main pipe in the direction of the medium flow to prevent condensate in the main pipe from flowing back into the branch pipe, and to reduce the back pressure of the safety valve. When there are shut-off valves on the inlet and outlet pipelines of the three-lobe rotary blower safety valve, a single gate valve should be selected, and it should be sealed with lead, with the valve rod installed horizontally to prevent the pin connecting the valve rod and the valve plate from corroding or loosening, causing the valve plate to slide down. When the safety valve is equipped with a bypass valve, this valve should be sealed closed.

2022-06-11

What is the relationship between the current and pressure of a three-lobe rotary blower?

The three-lobe Roots blower generates greater pressure with increased power under equal speed and voltage conditions. Since power = voltage x current, this means that under equal speed and voltage conditions, a larger current results in greater power, and thus greater pressure. The speed of a three-phase motor is fixed; when pressure builds up, the motor load increases, which can lead to overcurrent and motor burnout. The pressure range is from 9.8 kPa to 98 kPa, but it will not be too high. The three-lobe Roots blower is a positive displacement blower, and the air volume delivered is proportional to the speed. Each rotation of the three-lobe impeller performs three suction and discharge cycles with two impellers. Compared to the two-lobe type, gas pulsation is reduced, load variation is small, mechanical strength is high, noise is low, and vibration is also minimal. Two three-lobe impellers are mounted on two parallel shafts, maintaining a small gap between the impellers, the elliptical casing inner surface, and each impeller. As the impellers rotate in opposite directions at a constant speed, the gas enclosed by the casing and impellers is transported from the intake side to the discharge side. Because the impellers rotate in opposite directions at a certain speed, a specific amount of gas enclosed by the casing and impellers is transported from the intake side to the discharge side. Since the Roots blower is a constant flow blower, the main working parameter is the air volume, and the output pressure depends on the changes in the pipeline and load, with very little variation in air volume.

2022-06-08

Mingfeng Machinery takes you to understand whether the maintenance of Roots blowers is convenient or not?

The Roots blower is broken and needs repair. Generally, it is chosen to be sent back to the factory for repair. There are relatively few shops in the market that specialize in repairing Roots blowers, unlike car repair shops, which are abundant in every street and alley. The specific repair price needs to be determined based on the damage condition of the Roots blower. Below, the editor from Mingfeng Machinery will provide you with more details. Generally speaking, damage to the Roots blower requires factory repair. We have also mentioned in previous articles that after the Roots blower is sent back for repair, various tests need to be conducted to ensure the safety and stability of the equipment. Therefore, if factory repair is needed, the costs will include shipping + repair fees. The damage condition of each Roots blower is different, and the manufacturer's regulations vary, so the repair prices also differ. If the Roots blower we are using is relatively close to the manufacturer, requesting on-site repair is quite convenient and costs less. On-site repairs are mostly for minor issues with the Roots blower. If there are major problems, it still needs to be sent back for repair. For solving minor issues, the cost of on-site repair includes: labor costs + repair fees + accommodation costs. If the damage to the Roots blower is not severe and only has some minor faults, we recommend that customers seek professional repair personnel for inspection.

2022-06-06

Mingfeng Machinery takes you to understand the causes of wear on the impeller of the three-lobe Roots blower.

With the use of the three-lobe rotary blower, impeller wear is a significant issue that cannot be ignored. There are many reasons for wear, making it quite complex, but what are the causes of impeller wear in three-lobe rotary blowers? Surface fatigue stress (or temperature or impact) leads to surface cracks and flaking. The solid particles dispersed between the interfaces create a filing effect under relative motion and wear, resulting in concave surfaces and uneven contact areas. This has a considerable impact on the degree of wear on the impeller. In three-lobe rotary blowers, solid particles clean the metal surface, forming surface scratches. If other conditions are the same, improving machining accuracy and surface cleanliness does not reduce wear. On the contrary, due to the tight interface and significant molecular adsorption function, interface wear increases. This is called adhesive wear. Impeller wear in three-lobe rotary blowers can lead to equipment tripping.

2022-06-01

What should be noted in the daily inspection of the Roots blower?

Mingfeng Machinery reminds you: When servicing the Roots blower, it is important to protect the machine to avoid damage to the Roots blower, and also to ensure your own safety. Additionally, when disassembling the drive belt, be careful not to get your hands caught, and use an oil pan to catch the oil when draining the oil tank to prevent spills on the ground; when using a sledgehammer for disassembly, do not wear gloves, and surrounding personnel must remain focused to prevent injury from the sledgehammer; when disassembling the bearing of the Roots blower, pay attention to the striking areas of the inner and outer rings to avoid damaging the bearing; all disassembled pipes connected to the system and the pump casing must be properly wrapped to prevent foreign objects from entering; risk analysis during the disassembly phase. Before lifting the motor, electrical personnel must check the wiring for accuracy; when using electric tools, a leakage protector must be used, and the wiring is the responsibility of an electrician; each operation process must have the team leader conduct a safety briefing and prepare for potential hazards; when disassembling the coupling, use a coupling wrench and do not strike forcefully.

2022-05-30

Mingfeng Machinery explains the components of the centrifugal blower.

There are many types of blowers, and multi-stage centrifugal blowers are one of them. Multi-stage centrifugal blowers mainly consist of a stator, rotor, and rotating device. They are widely used in wastewater treatment, smelting blast furnaces, coal washing plants, mining flotation, chemical gasification, vacuum, and other fields, and can also be used to transport other special gases. Today, I will introduce the components of the multi-stage centrifugal blower. 1. Compact structure, beautiful appearance, good stability, and easy installation and maintenance. 2. Smooth operation, the optimized impeller reduces axial force to a low level, and the impeller efficiency is high. After static and dynamic balance correction, the whole machine runs smoothly, with a bearing amplitude of 0.04mm and no damping devices. 3. Low noise, during the operation of the blower, there is no mechanical friction, and the reasonable blade profile reduces the sound to a minimum. The noise generated by the multi-stage centrifugal blower is high-frequency noise, which can be isolated by any obstacles, so there is almost no noise outside the blower room. 4. Oil-free machinery, the bearings are lubricated with grease, and the bearing life exceeds three years. The fan does not produce oil and gas during operation. Special lithium disulfide molybdenum grease is required to lubricate the bearings. 5. The special composite profile of the impeller reduces internal leakage and improves volumetric efficiency. 6. Easy to adjust, the inlet butterfly valve adjusts the flow, and the outlet butterfly valve adjusts the pressure. 7. Usually, a two-pole asynchronous motor is used, but a four-pole motor can also be used for driving. Depending on the user's power grid, motors of different voltages can be used. 8. Sealing, in addition to the inlet ring, labyrinth seals are also installed at both ends of each stage impeller and between the stages and the casing to prevent gas leakage. 9. Cooling, the exhaust bearing seat has both air-cooled and water-cooled structures. As the impeller gradually compresses the gas, the temperature of the exhaust casing is much higher than that of the intake casing. There are air-cooled or water-cooled devices in the exhaust bearing seat to extend the bearing's service life.    10. Bearing temperature control alarm, the accessory is equipped with a temperature control box, connected to the bearing through a PT100 resistor. When the bearing temperature exceeds the set temperature, the temperature control box will automatically alarm.

2022-05-27