Application research of air suspension centrifugal blower in energy saving and noise reduction in cement industry

Wang Xinming (Weifang Fuyuan Turbocharger Co., Ltd., Weifang, Shandong 261205)

Abstract: The air suspension centrifugal blower is a new type of environmentally friendly centrifugal blower with high efficiency and energy saving. This paper introduces the structure, composition and operation principle of the air suspension centrifugal blower. Compared with the traditional blower, it has the advantages of energy saving, low noise, oil-free, reliable operation and It has the advantages of simplicity, long service life, no need for supporting auxiliary systems, small footprint and small maintenance workload. Combined with the actual case of energy-saving renovation of a cement plant fan, it is proved that the air suspension centrifugal blower replaces the Roots blower and is used for pulverized coal in the rotary kiln of the cement enterprise. In the production links such as conveying, air supply, and raw meal storage, the energy saving effect is remarkable, and the noise is significantly reduced.

Keywords: air suspension centrifugal blower, cement, material conveying, gas conveying, power consumption, noise.

Foreword:

Blowers play an important role in the cement production process. Under the current background of energy conservation and emission reduction, conversion of old and new kinetic energy, and normalization of peak shift production, the environmental protection situation of the cement industry is becoming more and more severe, and energy conservation and consumption reduction are imperative. In cement production, the energy consumption of fans is huge, accounting for about 30% to 35% of the total energy consumption. Doing a good job in energy saving and consumption reduction of blowers plays a key role in energy saving and consumption reduction in cement production. The traditional blower has encountered a bottleneck here; the air suspension centrifugal blower provides an idea to solve this problem, abandoning the systems such as speed-increasing gears, couplings, lubrication and cooling fans necessary for traditional blowers, using permanent magnet synchronous high-speed motors, Air dynamic pressure foil bearing, ternary flow centrifugal impeller, frequency conversion control and other technologies can adjust the speed according to the working conditions to ensure the efficient operation of the equipment, thus effectively reducing energy consumption, avoiding noise, vibration and waste lubricating oil, etc. The secondary pollution to the environment reduces the workload of equipment maintenance and saves equipment maintenance costs. It is of key practical significance for the high-quality development of the cement industry and the improvement of the competitiveness of cement enterprises.

1 Introduction of air suspension centrifugal blower

1.1 Principle

The air suspension centrifugal blower is a high-speed turbine equipment with an integrated and compact design and a skid-mounted structure. The basic principle is to directly drive the coaxial centrifugal impeller to do work through the permanent magnet synchronous high-speed motor supported by the air suspension bearing and controlled by the frequency converter. The compressed air is discharged from the air outlet of the volute; the continuous operation of the centrifugal impeller ensures that the air is continuously inhaled and discharged, so as to achieve the purpose of continuous blowing. The high-performance frequency conversion control technology makes the control strategy of the blower simpler, the operation more stable, and the adjustable working range is wider.

1.2 Structural composition

(1) Air dynamic pressure foil bearing

The air dynamic pressure foil bearing is a dynamic pressure air bearing supported by elastic foil. Before the blower starts, there is physical contact between the rotor journal and the bearing. When the blower starts, the rotor and the bearing move relative to each other. The air flow is driven to generate air tension, so that the foil of the air bearing is opened and separated from the rotor. A complete air film is formed between the foil and the rotor under the aerodynamic effect. The bearing suspends the rotor through the air pressure field. During operation, there is no physical contact point between the rotary shaft and the bearing, no lubricating oil is required, and the energy loss is extremely low. The surface of the air bearing foil is coated with a high-temperature solid, which requires no maintenance, and can be started and stopped more than 20,000 times without failure. Calculated by starting and stopping once a day, it can run for 54.8 years and is a semi-permanent bearing.

(2) Permanent magnet synchronous high-speed motor

The motor adopts the world's advanced permanent magnet synchronous motor technology, which is driven and regulated by a high-performance inverter; the speed of the motor can reach 150,000 rpm, and the efficiency can reach more than 97%; the motor rotor is directly connected to the impeller, and there is no power transmission loss. The transmission efficiency can reach 100%.

(3) Three-element flow centrifugal impeller

The impeller is semi-open, adopts ternary flow theory design and parameter optimization, with high efficiency and wide flow range; the material is made of high-strength forged aluminum, which is processed and formed by a five-axis machining center, and has strong deformation resistance; the working point of the impeller has the highest efficiency It can reach 85%, and the service life is more than 30 years.

(4) Frequency conversion control and detection monitoring technology

The blower adopts PLC and vectorless frequency conversion speed control, and the speed of the permanent magnet motor is controlled by adjusting the frequency, and then the flow and output pressure of the blower are controlled to meet the needs of various working conditions. The intelligent control system can predict surge and realize on-site control, and the equipment is installed with detection and monitoring system to realize remote monitoring and data transmission.

1.3 Main performance advantages

(1) High efficiency and energy saving

The air suspension centrifugal blower adopts advanced technologies such as high-efficiency centrifugal impeller, air dynamic pressure foil bearing, permanent magnet synchronous high-speed motor direct drive and non-contact air dynamic pressure bearing. High efficiency of equipment operation. Compared with the traditional roots blower, it can save energy by 20%-30%; compared with the traditional multi-stage centrifugal blower, it can save energy by 15%-20%; compared with the gear speed-increasing single-stage centrifugal blower, it can save energy by 10%- 15%.

(2) No vibration, low noise

The air dynamic bearing technology makes the rotating parts and mechanical systems have no contact, no mechanical friction, smooth operation, no vibration, the noise of the whole machine at a distance of 1m from the equipment is less than 80dB, and no sound insulation device is required.

(3) No lubricating oil, no mechanical maintenance, easy maintenance

Air dynamic bearing technology and direct drive structure eliminates the need for complex gearboxes and oil bearing systems required by traditional fans, and the system does not require lubricating oil systems, so that no lubricating oil is required at all, no mechanical maintenance is required, and daily maintenance is only replacement. The air filter effectively reduces the maintenance cost of the user.

(4) High system integration

The local control and frequency conversion system are integrated into one, and the setting of various functions and the query of data such as equipment speed, temperature, pressure, flow, and power consumption can be realized through the control panel. High-efficiency filter, cooling system, anti-surge system, unexpected power failure and fault protection mode, real-time touch screen, etc., improve the convenience of operation and reduce the occurrence of operation accidents.

(5) Easy to install

The whole machine layout adopts integrated compact design, skid-mounted structure, small volume, easy installation and operation.