Roots Blower: An Efficient and Energy-Saving Solution for Industrial Gas Transfer

1. Product introduction

The Roots blower (Roots Blower) is a positive displacement blower with two three-lobe rotors that rotate relative to each other in a sealed space formed by the casing and side plates. Each rotor follows an involute or epicycloid curve, ensuring that all three lobes of each rotor are identical, as well as the two rotors themselves, significantly reducing manufacturing complexity. The rotors are machined using CNC equipment to ensure that regardless of their rotational position, they maintain a very small clearance while keeping the center distance between them constant. This design ensures that gas leakage remains within acceptable limits, making it widely applicable in industries such as wastewater treatment, pneumatic conveying, aquaculture, chemical processing, power generation, and metallurgy. By rotating two intermeshing rotors, the blower draws in gas from the inlet, compresses it, and then expels it, featuring a simple structure, stable operation, and easy maintenance.

(1) Main components

The Roots fan is composed of five parts: casing, wall plate, impeller, oil tank and muffler

• Casing: mainly to support (wall plate, impeller, muffler) and fix.
• Panel: mainly used to connect the casing and the impeller, support the rotation of the impeller, and play the effect of end face sealing.
• Rotor: is the rotating part of the Roots blower, divided into two blades and three blades. However, due to the three blades have many advantages such as smaller gas pulsation, less noise and more stable operation than two blades, it has gradually replaced the two blades Roots blower.
• Synchronous gear: ensure the synchronous operation of the impeller, reduce friction and noise.
• Bearings and seals: high quality bearings and seals are used to extend service life.
• Fuel tank: mainly used to store lubricating oil for lubricating gears and bearings.
• Muffler: used to reduce the noise generated by the pulsation of air flow when the Roots blower enters and exits 

(2) Working principle

The fan housing contains two sets of three-blade impellers, driven by a pair of synchronous gears to rotate in opposite directions. The intake volume is V1, and due to the rotation of the impellers, it creates low pressure, drawing in air with a volume of V2. As the resistance at the outlet increases, it generates high-pressure gas, thus expelling air. Since there is a certain gap between the impellers and between the impellers and the housing, there is no friction, allowing for long-term operation.

2. Product features

1Internet of things

The human-machine operation interface supports remote control; the intelligent control panel adjusts the pressure and flow as required; automatic fault alarm and record; remote control is realized by using mobile APP; anti-shock protection function.

2High efficiency frequency converter

High stability and reliability; adjustable air volume range 45%-110%; adjustable frequency 400-1000HZ according to different fan specifications; built-in DC reactor, power harmonics suppression, precision calculation, soft start.

High speed permanent magnet synchronous motor

The factory is located in Ganzhou, the hometown of rare earth, providing high performance permanent magnets for motors; adjust the speed, strong torque, energy saving 18%-40% compared with ordinary motors;

Double gear box Roots main engine, 18 years of stable service life

3. Performance features

Due to the adoption of three-blade rotor structure and reasonable structure at the inlet and outlet of the shell, the fan vibration is small and the noise is low.

The impeller and shaft are integral structure, the impeller is not worn, the performance of the fan is constant, and it can run continuously for a long time.

The fan has large utilization rate, high volume efficiency, compact structure and flexible installation mode.

The machine is complete, which can meet the needs of different users for different purposes. In addition, the Roots high efficiency energy saving fan developed by our company also includes the following features:

(1) High efficiency and stability

The Roots fan adopts the design of no internal compression, and the gas conveying is continuous and stable, which is suitable for occasions requiring constant flow. Its speed is proportional to the air volume, and it is easy to adjust, so that it can meet the requirements of different working conditions.

(2) Low noise operation

Modern Roots fans use a three-blade rotor design to optimize airflow pulsation and significantly reduce noise (typically controlled below 75dB), making them suitable for noisy environments.

(3) Strong overload resistance

Due to the mechanical conveying principle, the Roots fan can still maintain stable operation when the pressure fluctuates, suitable for high load conditions.

(4) Long life and easy maintenance

-Wear-resistant materials are used for key components to reduce wear.

-Modular design for easy disassembly and maintenance.

-Optimize the lubrication system to reduce the failure rate.

4. Energy saving advantages

Our Roots fan performs well in energy saving, which is mainly reflected in the following aspects:

(1) Efficient motor matching

Using IE3/IE4 high efficiency motor, reduce power loss and improve energy utilization.

(2) Frequency conversion control technology

By adjusting the speed with frequency converter (VFD), the energy consumption of the fan can be reduced at low load, and the energy saving rate can reach 20%~40%.

(3) Optimize the impeller design

The three-leaf gradually open linear impeller reduces gas backflow, improves volumetric efficiency and reduces useless power consumption.

(4) Intelligent monitoring system

Some high-end models are equipped with intelligent control system to monitor pressure, temperature, vibration and other parameters in real time, and automatically adjust the operating state to avoid energy waste.

5. Application fields

• Sewage treatment: used in the aeration system to provide oxygen to promote microbial decomposition of organic matter.
• Air conveying: conveying powder, granular materials, such as cement, grain, etc.
• Aquaculture: oxygenation, improve the oxygen content of water, promote fish growth.
• Chemical and metallurgy: used for gas circulation, reactor gas supply, etc.
• Power industry: gas transportation in desulfurization and denitrification process.

6. How to choose the right Roots blower?

Roots Blower Selection Guide: Key Factors and Practical Recommendations

Proper selection of Roots blowers directly impacts operational efficiency, energy consumption, and service life. Below are the core considerations and practical recommendations for professional equipment selection:

1Basic Selection Parameters

Airflow (Capacity)

- Unit: m³/min (standard conditions)

- Calculation Methods:

- Process demand method: Based on aeration requirements, material conveying volume, etc.

- Empirical formula: e.g., wastewater treatment typically requires 0.03-0.05m³ air/m³ wastewater·h

- Recommendation: Allow 10-15% margin to avoid full-load operation

Pressure (Differential Pressure)

- Unit: kPa or mbar

- Key Considerations:

- System resistance (pipeline + terminal equipment pressure loss like diffusers/filters)

- Water depth (aquaculture requires static water pressure calculation)

Examples

- Wastewater treatment: 49-58.8kPa

- Pneumatic conveying: Typically 58.8-98kPa depending on material characteristics (powder > granules)

Medium Characteristics

- Clean air / corrosive gases / dust-laden gases

- High-temperature applications require special materials (e.g., stainless steel rotors)

2 Advanced Selection Factors

Speed Selection

Rotor Type Comparison

Motor Matching

- Power Calculation Formula:

  P = (Q×ΔP)/(60×η) × K

  (Q: Flow rate, ΔP: Pressure difference, η: Efficiency 0.7-0.9, K: Safety factor 1.1-1.3)

- VFD Control Selection:

- Recommended when load fluctuation exceeds 30%

- VFD-equipped models can save 25-40% energy

Special Condition Handling

High-Temperature Environments

- Selection adjustments:

- Material upgrade (cast iron → stainless steel)

- Add intake cooling devices

- Reduce rated speed by 10-15% 

Corrosive Gases

- Protective measures:

- Epoxy resin coating

- Titanium alloy rotors

- Pre-install chemical filters 

High-Altitude Locations

- Correction formula:

  Actual Q = Rated Q × (Local P/Standard P)

Energy Efficiency Optimization

System Matching:

   - Avoid "oversizing": Operating pressure should be ≥70% of rated pressure

   - Parallel operation: Multiple small blowers are more efficient than a single large unit

Pipeline Design:

   - Pressure loss: ~0.1kPa per 10m straight pipe

   - 90° elbow ≈ 2-3kPa pressure loss

   - Recommended flow velocity: 10-15m/s

Selection Process

1. Determine process requirements → 2. Calculate airflow/pressure → 3. Select rotor type → 4. Determine speed → 5. Match motor → 6. Special configurations → 7. Energy efficiency verification

 Common Selection Mistakes

- Selecting based solely on nameplate data, ignoring system resistance

- Excessive safety margin (>30%)

- Neglecting medium temperature effects on seals

- Considering low-speed torque for VFD selection

Recommendation: For complex conditions, provide suppliers with:

- Medium composition and temperature

- Installation space constraints

- Daily operating hours/start-stop frequency

- Local power supply stability

Scientific selection can optimize Roots blower performance, reducing energy consumption by 15-25% and extending service life by 3-5 years.

Determine air volume and pressure: calculate the required air volume (m³/min) and pressure (kPa) according to process requirements.

Select motor power: match the appropriate power to avoid "big horse pulling a small cart" phenomenon.

Consider noise and environment: if you are sensitive to noise, choose a low noise model or install muffler.

Energy saving requirements: priority to choose frequency conversion models or high efficiency motor versions.

Conclusion

With its high efficiency, stability and energy saving characteristics, Roots blower has become an ideal choice in the field of industrial gas conveying. With the progress of technology, new types of Roots blower are constantly improving in terms of energy efficiency and intelligence, providing users with more economical and environmentally friendly solutions.