4-1, the inhalation process.
As the Roots rotor rotates, air is drawn in until the intake port is closed.
1-2, External compression process.
It can be broken down into two processes. The Roots rotor continues to rotate, during which the volume of the enclosed space remains unchanged and there is no internal compression—until the enclosed space is suddenly exposed to the exhaust port, at which point the pipeline network exerts pressure, causing the air pressure in this section to rise.
2-3, Exhaust process.
As the Roots rotor continues to rotate, the already pressurized air is discharged into the pipeline network.
RHG Permanent Magnet Variable Frequency Screw Blower
Category:
Advanced coating technology (Teflon) reduces the rotor clearance, enhancing volumetric efficiency while effectively protecting the rotors and extending their service life.
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Description
As a new environmentally friendly and energy-saving product, the RHG permanent-magnet variable-frequency screw blower can be widely used in various industries—including wastewater treatment, cement, chemical, power, steel, textile, and pneumatic conveying—all of which are vital sectors for people’s livelihoods. It enjoys broad market application and high demand.
Performance range
Medium being conveyed: air, nitrogen, and other inert gases
Startup method: Permanent magnet variable frequency
Flow rate: 3–110 m 3/min
Boost pressure: 30-150 kPa
Performance characteristics 
1. Advanced coating technology (Teflon) reduces the rotor clearance, enhancing volumetric efficiency while effectively protecting the rotors and extending their service life.
2. Use bearings from world-renowned brands to ensure reliability.
3. Unique lubrication and oil drainage channels ensure that bearings and gears are well-lubricated and cooled, while also improving the efficiency of the main unit.
4. The combination of labyrinth seals and carbon ring seals is used to achieve oil-gas isolation between the compression chamber and the lubrication chamber, ensuring 100% oil-free air.
5. Since the compressed gas is lubricated without oil, the entire system does not require oil-gas separation, resulting in a simpler structure.
Performance advantages
Compared to traditional Roots blowers:
1. Higher efficiency, lower noise, and better reliability;
2. Allows higher rotational speeds and tip speeds;
3. It can achieve higher exhaust pressure.
Series parameters
| Series | Model | Traffic (m 3 /min) | Exhaust pressure (bar) | Rotational speed (revolutions per minute) |
| RHG115 | RHG115RA-I | 3.8~7 | 0.4~1 | 3350~5350 |
| RHG115RB-II | 5~9 | 1.0~1.5 | 3350~6000 | |
| RHG170 | RHG170RA-I | 10~17 | 0.4~1 | 2600~4000 |
| RHG170RB-II | 13.5~22.5 | 1.0~1.5 | 2600~4000 | |
| RHG210 | RHG210RA-I | 20~34 | 0.4~1 | 2400~3800 |
| RHG210RB-II | 25~43 | 1.0~1.5 | 2400~3800 | |
| RHG280 | RHG280RA-I | 26~65 | 0.4~1 | 2000~3300 |
| RHG280RA-II | 1.0~1.5 | |||
| RHG300 | RHG300RA-I | 64~110 | 0.4~1 | 2000~3300 |
| RHG300RA-II | 1.0~1.5 |
Working principle
4-1 (Figure 1-2), the inhalation process.
As the screw rotor rotates, the volume of the screw grooves gradually increases, drawing air into the blower.
Until the intake port is closed.
1-2 (Figure 3 above), internal compression process.
The intake port is already sealed, and the exhaust port has not yet been opened. Due to the spiral design, the counter-rotating motion...
The movement causes the enclosed screw groove volume to become progressively smaller, resulting in internal compression and a rise in pressure.
2-3 (Figure 4 above), exhaust process.
As the rotor continues to rotate, the exhaust port opens, and the compressed air is discharged from the main unit.
Advantageous features
1/Low energy consumption
Energy loss generated by Roots technology
1→2: Inhale. Air enters the compression chamber.
2→3: External compression. The air is compressed externally due to the back pressure in the pipeline network.
3→4: Exhaust. Air is expelled from the pipeline. The blue area represents the compression work, which is directly proportional to energy consumption.
Energy-saving effects of screw technology
1→2: Inhale. Air enters the compression chamber.
2→3: Internal compression. As the rotors mesh with each other, the air volume decreases.
3→4: Exhaust. Air is expelled from the pipe.
The energy-saving power consumption resulting from internal compression is directly proportional to the area of the blue region.
Under the same flow rate and pressure conditions, screw blowers require significantly less power consumption.
In the diagram, the light green area represents the energy savings.
Compared to Roots blowers, the higher the pressure, the more significant the energy-saving effect—average energy savings can exceed 15% to 30%!
2/Low noise
The screw rotor generates low aerodynamic noise. Because the screw rotor performs work with internal compression, it eliminates pressure surge noise caused by the pressure difference between the blower outlet and the pipeline pressure, ensuring smooth gas flow. The corrugated inlet and exhaust ports minimize fluctuations in the airflow.
3/ High Integration
4/ Highly Intelligent
The Rongheng screw blower is equipped with a mature and systematic operation control system. The main unit uses a control screen as the human-machine interface, providing a Chinese/English operating display system that is simple and intuitive to use.
Automated control provides comprehensive blower maintenance information and delivers maintenance alerts. It can also log historical alarms, enabling users to easily analyze the actual parameters of the process system. Additionally, it supplies monitoring signals to the host computer. No dedicated personnel are required for supervision, reducing labor costs and improving operational efficiency.
5/ High stability
Rongheng Energy-Saving Screw Blower
Compared to Roots blowers: The unit has low leakage, low temperature rise, and strong pressure boosting capability, with a maximum pressure boost reaching 200 kPa.
Compared to centrifugal blowers: Strong adaptability to operating conditions, no surge, and flow rate hardly varies with pressure changes.
6/ Wide performance range
The standard configuration of the Rongheng screw blower features a permanent-magnet variable-frequency motor. The unit’s start-up and shut-down processes place no impact on the power grid, and the unit can perform stepless, constant-pressure flow regulation within a range of 40% to 100%.
It can adapt to operating conditions with wide-ranging performance fluctuations, reduce power consumption for non-process needs, provide tailored gas supply to the gas-using system, and further enhance energy-saving effects.
Comprehensive Comparison
Energy Consumption Comparison
The high resistance encountered by the airflow inside a Roots blower will lead to an increased pressure drop and higher energy consumption. Loss factors:
1. External compression
2. Pulley滑动
3. Muffler
4. Imported filter
At a pressure of 0.8 bar, the Roots blower delivers a flow rate of 1600 m³/h and consumes an average of 61 kW.
The internal air passages of the RHG series oil-free screw blowers have been optimized to reduce pressure drop and air turbulence.
Saving factor:
1. Internal compression
2. Integrated gearbox
3. Smooth silencer
4. Air intake filter
At a pressure of 0.8 bar, the screw blower consumes an average of only 42 kW to deliver a flow rate of 1600 m³/h.
| Energy Consumption Comparison Parameters | Roots 75 kW | RHG55-0.8 |
| Shaft power (kW) | 61 | 42 |
| Pressure air volume 0.8 bar (m³/min) | 36 | 38 |
Power consumption for one year of operation (8000 hours) | 488,000 degrees | 336,000 degrees (When converted to the same gas production capacity as Roots blowers, the energy-saving efficiency is even greater.) |
| The cost of operating for one year (At 1.0 yuan per kilowatt-hour) | 488,000 yuan | 336,000 yuan |
| Conclusion | RHG55-0.8 saves annual operating costs by 152,000 yuan, with an energy-saving rate of around 30%. | |
Keep running continuously
In harsh and dusty application environments, a reliable compressed air supply is crucial for ensuring continuous production. The RHG series oil-free screw blowers are designed, manufactured, and tested in compliance with GB/T15487 standards. Their fully enclosed IP54 motors guarantee continuous operation even in dusty and humid environments, offering enhanced reliability.
Protect your reputation and production.
In nearly all applications, oil contamination in compressed air can lead to serious production problems, thereby increasing costs. The RHG series oil-free screw blowers set a new standard for air purity, providing superior protection for critical applications and meeting today’s increasingly stringent air quality requirements.
Convenient installation
Once delivered, the RHG series oil-free screw blowers are ready for immediate use. The complete supply package eliminates the need for customers to make any additional purchases, simplifying the installation process to a certain extent and saving you time and costs. The RHG series oil-free screw blowers can be directly installed into existing compressed-air pipelines and started up and operated right away.
Application Comparison
| Fan type | Roots blower | Single-stage high-speed centrifugal blower | Air-suspended blower | Rongheng Screw Blower |
| Working principle | Backpressure accumulation | Convert kinetic energy into pressure potential energy. | Convert kinetic energy into pressure potential energy. | Internal compression + backpressure accumulation |
| Pneumatic efficiency | Lower | High | High | High |
| Single-stage boost capability | ≤100kpa | ≤150kpa | ≤150kpa | ≤200kpa |
| Pneumatic performance stability | Stability | Pressure fluctuations significantly affect flow rate; overpressure surge and low-pressure overload both result in low efficiency. | Pressure fluctuations significantly affect flow rate; overpressure surge and low-pressure overload both result in low efficiency. | Stability |
| Surge phenomenon | None | There is | There is | None |
| Airflow adjustment range | Add a frequency inverter Constant pressure adjustment: 30~100% | Constant pressure adjustment: 70~100% | Constant pressure adjustment: 70~100% | Constant pressure adjustment: 30~100% |
| Noise level dB | 95~110 | 90~100 | 75~85 | 75~85 |
| Vibration | ≤11.2 mm/s | ≤4 mm/s | ≤1.8 mm/s | ≤1.8 mm/s |
| Service life | 5-10 years | 10 years | 10 years (Frequent failures occur two years later) | 10 years |
| Major service interval | Major maintenance every 3 years; the fan has a simple structure, requires minimal maintenance, and features low repair and replacement costs. | Major maintenance every 3 years; complex structure with high repair costs; dedicated maintenance by the vehicle manufacturer’s specialists. | The unit has a simple structure and high technological content, but after two years, it has begun experiencing frequent failures, and users are essentially unable to repair it. | Major maintenance every 3 years; the fan has a simple structure, requires minimal maintenance, and features low repair and replacement costs. |
| Installation and Construction Requirements | Customized foundation required with additional soundproofing measures. | Custom-made foundations require additional soundproofing measures. | The integrated skid-mounted structure requires no fixing or soundproofing measures and is easy to install. | The integrated skid-mounted structure requires no fixing or soundproofing measures and is easy to install. |
| Acquisition cost | Low | High | High | middle |
Case Study
| Industrial Wastewater Treatment and Renovation Project | ||
| Type | Original Roots blower | Rongheng Screw Blower |
| Quantity | One on, one standby | 1 unit (1 unit replaces 2 units) |
| Operating parameters | 75 kW, 22 kW, 0.6 bar, 40 m 3/min | 45 kW, 0.6 bar, 41 m 3/min |
| Energy-saving analysis | One Rongheng oil-free screw blower replaces two existing Roots blowers, achieving an energy-saving rate of over 38%. | |
| Textile Spinning and Elongation Low-Pressure Piston Machine Retrofit Project | ||||||||||||||||||||||||||||||||
| Type | Original low-pressure piston machine | Rongheng Screw Blower | ||||||||||||||||||||||||||||||
| Quantity | One on, one standby | 1 unit (1 unit replaces 2 units) | ||||||||||||||||||||||||||||||
| Operating parameters | 75kW, 1.5 bar, 25m 3/min | 45 kW, 1.2 bar, 26 m 3/min | ||||||||||||||||||||||||||||||
| Energy-saving analysis | One Rongheng oil-free screw blower replaces two original low-pressure piston machines, achieving an energy-saving rate of over 39.6%. | |||||||||||||||||||||||||||||||
Application fields
Keywords: High-temperature Roots blower, Biogas booster fan
Product Message
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Address: No. 666 Fengcheng New Street, Yudong Town, Haimen City, Jiangsu Province, China.
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