Roots Blower

Roots blower is a positive displacement blower, mainly composed of impellers, rotating shafts, gears, bearings and other components.Roots blower uses two or three blade rotors to perform relative motion in the cylinder for compressing and transporting gas.Roots blower has the characteristics of simple structure, convenient manufacturing, oil-free medium during transportation, easy maintenance, long service life and low vibration of the whole machine. It is widely used in metallurgy, chemical industry, chemical fertilizer, petrochemical, instrumentation and building materials industries. It can also be used for oxygenation in aquaculture, aeration in sewage treatment and cement transportation. It is more suitable for gas transmission and pressure boosting systems in low-pressure occasions and can also be used as a vacuum pump, etc.

Roots blower transports gas by relying on the change of the working chamber volume formed when two involute "8"-shaped rotors rotate.Roots blower is the first-choice product for transporting media such as clean air, clean gas, sulfur dioxide and other inert gases, as well as for the special gas industry (gas, natural gas, biogas, carbon dioxide, sulfur dioxide, etc.) and high-pressure working conditions.In view of the above characteristics, it can be widely adapted to the metallurgy, chemical industry, chemical fertilizer, petrochemical, instrumentation and building materials industries.

Working Principle of Roots Blower:

Roots blower is a high-volume blower. It separates the inlet and exhaust ports through a pair of rotors "meshing" (there is a gap between the rotors and they do not contact each other).The rotors move in opposite directions by a pair of synchronous transmission gears, pushing the inhaled gas from the suction port to the exhaust port without internal compression.When the gas reaches the exhaust port, the gas is pressurized due to the backflow of high-pressure gas on the exhaust side, thus completing the gas transportation.The two rotors do not contact each other, and the seal between them is achieved by a strictly controlled gap, so the gas is not contaminated by lubricating oil.

Composition Structure of Roots Blower:

• Roots blower is composed of five main parts: casing, wall plate, impeller, oil tank and muffler.
• Casing: It mainly plays the role of supporting (wall plate, impeller, muffler) and fixing.
• Wall plate: It is mainly used to connect the casing and the impeller, support the rotation of the impeller, and achieve the effect of end face sealing.
• Impeller: It is the rotating part of the Roots blower, which is divided into two-blade and three-blade types. However, due to the many advantages of three-blade impellers such as smaller air outlet pulsation, lower noise and more stable operation compared with two-blade impellers, three-blade Roots blowers have gradually replaced two-blade Roots blowers.
• Oil tank: It is mainly used to store lubricating oil for lubricating gears and bearings.
• Muffler: It is used to reduce the noise generated by air flow pulsation when the Roots blower inhales and exhausts air.

Classification of Roots Blower:

• According to different working methods, Roots blowers can be roughly divided into single-stage and double-stage types. Among them, the blower with only one compression stage is called a single-stage blower, while the blower that connects two single-stage blowers in series and compresses the gas twice continuously is called a double-stage series blower.
• Classified by the number of impeller heads: two-blade Roots blower and three-blade Roots blower.
• Classified by purpose: vertical kiln blower, gasification blower, aeration blower, etc.
• Classified by medium type: air blower, gas blower, hydrogen blower, sulfur dioxide blower, etc.
• Classified by transmission mode: direct-connected blower and belt-connected blower, etc.
• Classified by cooling method: air-cooled blower, water-cooled blower and countercurrent cooling blower, etc.
• Classified by structural form: vertical blower, horizontal blower, vertical shaft blower, compact group blower, etc.
• Classified by sealing form: blowers with various sealing forms such as labyrinth seal, expansion ring seal, packing seal and mechanical seal.

Application of Roots Blower:

As a typical gas pressure boosting and transmission machine, Roots blower has a wide range of applicable characteristics in its specific pressure range.In terms of application, most Roots blowers are used as air blowers, and their applications cover many fields such as building materials, electric power smelting, chemical industry and petrochemical industry, mining, ports, light industry and textiles, post and telecommunications, food and paper making, aquaculture and sewage treatment. When using a sealing device with good air tightness, it can also be used to transport gases other than air, such as hydrogen, oxygen, carbon monoxide, carbon dioxide, hydrogen sulfide, sulfur dioxide, methane, gas, etc. In addition, in some fields such as medicine, food chemical industry and petrochemical industry, Roots blowers are usually used as air source machines for various low-pressure pneumatic conveying systems.

Chemical industry: Roots blowers are widely used in the chemical industry. According to different working conditions, they are widely applied, such as transporting chemical raw materials, transporting reaction gases, aeration and stirring, etc.

Sewage treatment industry: In the sewage treatment industry, since the sewage tank needs to be filled with oxygen for microbial oxidation and decomposition, Roots blowers can provide a fixed amount of oxygen according to different water depths and treated water tons to promote microbial oxidation and decomposition.

Operating Conditions of Roots Blower:

• The inlet temperature of the conveyor medium generally cannot exceed 40 degree centigrade.
• The content of particles in the medium cannot exceed 100mg/m³, and the size of the particles cannot exceed half of the working interval.
• During operation, the bearing temperature cannot exceed 95 degree centigrade, and the lubricating oil temperature cannot exceed 65 degree centigrade.
• The working pressure cannot be higher than the pressure boosting range specified on the nameplate.
• The gaps between the impeller and the casing, the impeller and the side plate, and between the impellers of the Roots blower have been adjusted in the factory, and this gap must be ensured during reassembly.
• When the Roots blower is running, the oil level in the main oil tank and the oil tank should be between the two red lines of the oil level gauge.
• Check whether there are any unfixed parts at the inlet and outlet connection parts and whether the supporting points of the pipeline are complete. For blowers and vacuum pumps that require cooling water, it is necessary to ensure that the installation of cooling water meets the requirements.

Maintenance of Vertical Roots Blower:

• Always keep the surface of the machine and its surrounding area clean, free of dust and oil dirt. Frequently check the tightness of the connecting bolts in various parts and tighten the loose nuts.
• Frequently check whether the bearing temperature is overheated. The allowable temperature rise and maximum temperature of the Roots blower bearing and gearbox should comply with the provisions in the following table.
• Check the oil level gauge of the gearbox and reducer. The lubricating oil should be added to the specified scale line, not too much or too little. And frequently check whether the oil seal device has air leakage.
• Check whether the lubrication system of the machine is normal, select the correct lubricating grease (oil) to add, and regularly refuel or change the oil according to the cycle specified in the lubrication system.
• For blowers with gear oil pumps, check the operation status of the oil pump and whether the oil circuit is blocked.
• Frequently listen to the operation status inside the blower to check for friction, overheating and abnormal operation sounds.
• Make records according to the specified time in each shift. The records include the rated current, gas outlet temperature, outlet air pressure, outlet air volume of the blower during operation, etc.
• Establish various maintenance systems, such as the patrol inspection system.