Comparison between single-screw and twin-screw air compressors;
1, whole machine group comparison
A: shaft power: single screw: 5.6-6.2 kw；; Twin screw: 6.0-6.6.
B: Noise and vibration: single screw: no vibration and noise: 60-68dB.
Twin screw: high vibration and noise: 64-78dB.
C: bearing durability:
Single screw: radial and axial balance, long bearing life, rotor bearing 30 thousand hours, star wheel bearing 50 thousand hours.
Twin-screw: there is no balance at all, the load of the second rotor is extremely heavy, and the bearing life is short, generally: 8000-1.8000 hours, which requires professionals to start the machine frequently to replace the bearing, and the workload is heavy.
D: temperature: exhaust temperature of single screw.
2. Use cost:
Answer: Electricity charge (calculated in cubic meters per hour): single screw 3 * 5.6 * 250 * 8 = 33,600 kW/h,
Twin screw 3 * 6.5 * 250 * 8 = 39000 kw/h.
B: maintenance fee:
(1), 5-year warranty period: Li Zheng Seiko independently develops and produces, and has its own technology, so the cost is low and does not need to be controlled by others, and the services are all compared, which is equivalent to 2/3 of foreign brands.
At present, the technology and main head of twin-screw machine are mostly from abroad. China brand screw machine after-sales service price is unbearable for China people, but they can't afford other people's machines.
(2) After the five-year warranty period, the main screw (rotor) is guaranteed for life (tentatively for 30 years) and the star rotor is guaranteed for 8 years, which means that the products of our factory need to be replaced after 8 years, and the price is quite low.
The warranty period of the twin-screw machine is 5 years, because the life of the screw is generally 5 years. In the fifth year, the screw needs to be replaced, and its cost is equivalent to 1/3 of the overall price of the main machine.
Remarks: If the twin-screw machine runs for 30 years, the cost is equivalent to 1.5 times of a new main machine, while the single screw only needs to change the star wheel three times, and the price of the star wheel is quite low. The cost of this single screw is only about 10% of that of the twin screw.
C: Oil consumption: Because of the low working temperature of single screw, the requirement for oil itself is not high, so the cost is low.
Because of the high working temperature and high demand for oil, the twin-screw has high cost because the oil is carbonized and replaced many times at high temperature.
D: Bearing life: the single-screw bearing should be replaced every 30,000-50,000 hours. The twin screw is changed every 8000-1.8000 hours. (equivalent bearing SKF)
Second, the technical advantages of single screw air compressor:
Single screw air compressor not only has the advantages of high reliability, simple operation and maintenance, strong adaptability and no inertia, but also overcomes the shortcomings of double screw air compressor in design and structure, and is a new generation of air compressor developed. Replacing twin-screw air compressor with single-screw air compressor is an inevitable development trend and an inevitable choice for a modern enterprise. Americans say: "Single screw air compressor is a strategic product in 2 1 century". Compared with other air compressors, the single-screw air compressor has the following advantages:
1, reasonable structure and ideal force balance.
The star wheels are symmetrically arranged on both sides of the screw axis, and the radial forces of gas acting on the screw cancel each other, and the gas bearings acting in the screw groove also cancel each other, so that the screw is in a completely balanced state. Therefore, the bearing of the main engine is not affected by any axial and radial force, and the gas force on the star wheel is also very small, only about 1/30 of that of the piston air compressor or twin-screw air compressor, so the bearing of the main engine and the star wheel has a long service life.
2. The single machine has large capacity, no clearance volume and high volumetric efficiency.
The screw has six grooves, which are equivalent to six cylinders, and two star wheels are engaged with the screw grooves at the same time. Each revolution of the screw is equivalent to 12 cylinders, which makes full use of the space of the screw groove. Take a single-screw air compressor with a speed of 200 rpm as an example, and the compression times per minute are 3000* 12=36000 times. The depth of the spiral groove of the screw becomes shallow with the increase of pressure. At the end of exhaust, when the star gear teeth leave the spiral groove, the depth is 0, so there is no clearance volume, and the volumetric efficiency is much higher than that of the twin screw.
3, small vibration and low noise
Single screw air compressor has reasonable design, high speed and light load. Each revolution of the screw produces 12 compression cycles and exhausts nearly 35,000 times per minute. There is basically no exhaust pulsation phenomenon, so the vibration is very small. When the unit is running, putting a coin on the fuselage will not fall. The device does not need to install the foundation. In addition, it uses sound attenuation and sound insulation devices, so the noise is very low and a quiet working environment can be maintained. Can be installed in the production site, which can greatly reduce the pipeline loss caused by long-distance gas transmission.
4. The machining accuracy is higher.
Because the meshing pair and casing of single-screw air compressor have high requirements on geometric starting and mutual position, they must be processed with special high-precision equipment. Li Zheng Seiko exclusively owns a single-screw special processing machine called "China Special Plane" with high precision (foreign countries don't believe that there will be such a high-precision machine tool in China, and a large number of foreign experts have visited our factory), which is one of the reasons why Li Zheng Seiko's air compressor is in a leading position in the industry (there is also an exclusive three-wire technology, which has been patented in many countries).
5. The overhaul period is long. The overhaul, maintenance and operation costs are low.
The service life of the screw and the star wheel bearing of the single-screw air compressor is long, and the basic meshing pair has high machining accuracy, and the meshing pair is easy to achieve "zero stress" when contacting, so that the meshing pair will never wear; When the screw drives the star wheel, it only needs to overcome the friction of the star wheel bearing, and the value is very small, so the wear of the star wheel is also small and the service life is long. Single-screw air compressor can be repaired on site during overhaul, which is convenient to replace, so the cost is low. Because the single-screw air compressor has high volumetric efficiency, low lubricating oil temperature, difficult carbon deposition and long service life, the life of screw and star wheel bearing is prolonged. To sum up, the procedures listed are for reference only.