Application of Frequency Converter in Centrifuge

Separation machinery is a device that separates a liquid from a solid particle mixture, and is mainly classified into a centrifuge, a separator, a filter press, an oil filter, a filter, and the like. Separation machinery is generally a post-processing equipment in the process, so it is directly related to the quality of the final product. As a whole, there is a big gap between China's separation machinery technology level and foreign advanced level. Mainly manifested in: separation of machinery varieties, specifications, can not fully meet the needs of domestic production, especially the separation of materials with high viscosity, precision machinery, high efficiency, high production capacity, high degree of automation of the separation machinery depends on the import of the vast majority of; separation The research of mechanism and application technology is backward, the development speed of new products is slow; the manufacturing process is backward, the production efficiency is low, the product reliability and stability are poor, the technical level and automation level are low; the supporting equipment and materials cannot meet the needs of the production of separating mechanical products. In particular, the quality and reliability of the product are very unstable.

From the perspective of the development of the separation machinery, the digital AC inverter will replace the original electromagnetic speed control, DC speed control, hydraulic coupling speed control, multi-speed motor, and gradually become the main driving device of the separation machine. This article will introduce ABB's new ACS550 inverter in the design and application of the separation machine.

ACS550 is ABB's latest intelligent inverter, which is used for low voltage AC drive from 0.75KW to 355KW. It can accurately control the speed and torque, and can match the existing standard squirrel cage asynchronous motor. The ACS550 has three control modes, namely scalar V/F control, sensorless vector control, and torque control, so this inverter can not only be suitable for the simplest motor operation, but also can be applied in complex work situations. Its reliable overload capability design can also meet common loads and heavy loads at the same time.

Separation machinery drive motors are generally divided into single-motor drive and multi-motor drive two, this article will mainly introduce the application of ACS550 inverter as a single motor drive typical example of three-foot centrifuge and as a typical example of multi-motor drive Screw centrifuge application.

2. Application of Frequency Converter in Three-legged Centrifuge Three-legged centrifuge is a vertical centrifuge with simple structure, strong adaptability to materials and widest application area. Sedimentation and filtration are two major categories. The most widely used is a filter type three-legged centrifuge. It is suitable for the separation of fine particles having a particle size of only a few micrometers, and it can also be used for deliquescence of articles. By adjusting the duration of each operation step, it can be used to separate various suspensions with different filtering degrees of difficulty, and by adjusting the washing time of the filter cake, different washing requirements can be satisfied. This type of machine is mainly suitable for small and medium-sized production scales, but due to the above-mentioned many advantages, it is widely used in pharmaceutical, chemical, light industry, textile, food, machinery manufacturing and other industrial sectors.

In this application, the frequency converter drives the rotating drum of the centrifuge, which is stable in startup and adjustable in separation factor. It completely overcomes the disadvantages of high noise, high failure rate, short service life, and unstable rotation speed in conventional DC carbon brush centrifuges. , Gravity sedimentation equipment replacement product. AC frequency conversion centrifuge has distinctive features and originality in several important indicators such as damping system and variable frequency motor. The stand-alone drive power of the common three-legged centrifuge is between 3KW and 55KW, and the ACS550 is fully qualified.

Application principle of ACS550 in three-legged centrifuge The principle of ACS550 inverter is mainly divided into three parts in its peripheral circuit:

(1) The DC bus UDC+, UDC- terminate the brakes +, - end, and then according to different options (such as the feedback brake connected to the grid three-phase, energy consumption braking is connected to the braking resistor), Tk is the braking unit The internal relay, when this unit fails, Tk action, through the definition of the terminal DI4 of the inverter, immediately block the U/V/W output.

(2) Control circuit input and output terminals adopt the definition of macro 9902=5 DI1: manual/automatic start/stop (manual): get electric start DI2: forward/reverse (manual): electric turn is reversed DI3:EXT1/EXT2 selection: Power selection Automatic control DI4: Run permission: Once the drive is disconnected, it will stop