**Roots blower is a type of volumetric gas delivery equipment that uses two interlocked rotors to rotate inside the casing, forcibly pushing gas to achieve delivery or pressurization. Its name comes from the inventors, the American brothers Philonder and Francis Roots. The following is a systematic analysis of its core characteristics:
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**1、 Basic Definition**
1. * * Working principle**
-Belonging to * * Positive Displacement Blower * *, it achieves directional gas transportation through the periodic variation of the closed chamber formed by the rotor and shell.
-* * No internal compression * *: The pressure increase depends on the system back pressure (an external pressure relief valve is required to prevent overpressure).
2. * * Structural features**
-* * Core components * *: Three blade/two blade rotors driven by a pair of synchronous gears, precision machined cylinder body, and bearing sealing system.
-Non contact operation: Maintain a gap of 0.1-0.4mm between rotors and between rotors and the housing to avoid friction.
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**2、 Dynamic demonstration of working principle**
1. * * Inhalation stage**
-Separation of rotor → increase in intake chamber volume → formation of negative pressure to suck in gas.
2. * * Closed Conveyor**
-The gas is enclosed in the chamber formed by the rotor and cylinder body.
3. * * Exhaust Stage**
-The chamber is connected to the outlet → gas is forcibly discharged.
(The relationship between rotor rotation and airflow direction can be visually displayed through animated illustrations)
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**3、 Performance characteristics**
|* * Features * * | * Roots blower * * | * * Comparison with centrifugal blower * *|
|----------------|------------------------------|-----------------------------|
|* * Flow regulation * * | Can only be adjusted through speed regulation (variable frequency control) | Can be adjusted through valve/speed dual regulation|
|* * Pressure characteristics * * | Flow rate hardly changes with pressure | Flow rate significantly decreases as pressure increases|
|Efficiency range * * | 50~70 | 75~85|
|* * Medium adaptability * * | Can handle dusty and corrosive gases | Only suitable for clean gases|
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**4、 Core application areas**
1. * * Environmental Protection Engineering**
-Wastewater treatment aeration (accounting for over 40% of global Roots blower usage)
-Supply of desulfurization and oxidation air
2. * * Industrial Conveyor**
-Fly ash/cement pneumatic conveying (pressure up to 98kPa)
-Chemical reactor gas circulation
3. * * Special Scenarios**
-Vacuum packaging (single machine ultimate vacuum -80kPa)
-Metallurgical blast furnace oxygen enriched blowing
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**5、 Key parameters for selection**
1. * * Flow rate * * (m3/min): Based on process requirements+10 margins
2. * * Pressure * * (kPa): system resistance+liquid column height, etc
3. * * Medium characteristics * *:
-Corrosive gas → Stainless steel 316L shell
-Dust containing gas → Wear resistant coating impeller
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**6、 Differences from Similar Devices**
1. * * VS screw fan**
-Roots blower: no internal compression, suitable for medium and low pressure (＜ 200kPa)
-Screw fan: with internal compression, the pressure is higher (up to 400kPa), but the price is 2-3 times more expensive
2. * * VS centrifugal fan**
-Roots blower: constant flow rate, suitable for control
-Centrifugal fan: energy-saving, suitable for high flow clean gas
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**7、 Typical structural schematic diagram**
```
Air inlet → muffler → rotor compression chamber → exhaust outlet → check valve
↑
Synchronous gear drive
```
(Actual equipment includes accessories such as lubrication system, valves, pressure gauges, etc.)
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**8、 Development and Evolution**
-* * Generation * *: Two blade rotor (high pulse, high noise)
-* * Modern mainstream * *: Three blade rotor (smooth airflow, reduced noise by 15dB)
-Cutting edge technology: Magnetic levitation bearing Roots blower (no mechanical friction, energy efficiency improvement of 20%)
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**Summary: Roots blower is the "working mother machine" for industrial gas transportation. With its three advantages of simple structure, resistance to harsh working conditions, and stable flow rate, it is irreplaceable in fields such as environmental protection, chemical industry, and power. However, attention should be paid to its disadvantages of low efficiency and high noise. When selecting, the most suitable model should be matched based on pressure, medium characteristics, etc.
