Pulp production line is composed of a series of supporting equipment. In order to increase production efficiency and ensure the quality of pulp, each transmission part needs a high degree of coordination. At present, important transmissions of advanced production lines are all driven by frequency converters. Wood pulp refiner is a key to pulp production. In part, this paper uses Inventronics' Goodrive300 inverter as an example on a large-scale pulp production line to illustrate the requirements of the control system for the pulping line and the electrical drive requirements of the large wood chip refiner.
Pulp is a basic raw material for papermaking. Due to the lack of timber resources in China and the lack of large-scale pulp production equipment, pulp is far from meeting the needs of the ever-growing paper industry. At present, China's per capita paper consumption is only 27-30 kilograms. The amount of paper used is 200-300 kg. In order to make up for the shortage of raw materials, pulp products are imported from abroad a considerable amount of pulp.
Pulp raw materials mainly include wood fiber, bamboo, reed, straw, wheat straw, stalks, cotton stalks, bagasse, rags, waste cotton, and waste hemp.
Pulping is the process of dissociating plant fiber raw materials into natural pulp or bleaching pulp by using a chemical method or a mechanical method or a combination thereof. The following is the introduction of reed papermaking as an example to introduce its basic process.
The wood chip refiner is a key equipment for the production of pulp. The wood is first cut into wood chips and the wood chips are ground directly in a high-power disc refiner. The wood chip refiner is shown in the figure.
Because the pulp production line is composed of a series of supporting equipment, the transmission parts need a high degree of coordination. The current important drive lines of the production line are all driven by frequency converters. This paper uses Inven Electric Co., Ltd. Goodrive300 inverter in the pulp of a Fortune 500 company. The application of the production line as an example illustrates the requirements of the control system of the pulp production line and the electric drive requirements of the large wood chip refiner.
Second, pulp production line control system
The entire production equipment control system topology shown in Figure 3, the central control system DCS and the entire production line between all the implementation of components and sensors between PROFIBUS communication, in order to ensure the safety of the production line, all key drive equipment are installed near the camera, DCS passed Ethernet captures all camera data and monitors the field conditions of each drive system in real time.
The central control system controls the start and stop, frequency setting, fault reset and other commands of all inverters. At the same time, the current, voltage, bus voltage and operating frequency of all inverters are collected to monitor each inverter in real time.
Third, wood chip refiner electrical drive features
The power of the wood chip refiner in the pulping production line is driven by a 250kW three-phase asynchronous motor, the rated voltage of the motor is 690V, the synchronous speed is 1500 rpm, and the inverter is manufactured by Goodwill 300 inverter machine customized by Inventronics Co., Ltd. Rated output power is 280kW.
The large wood chip refiner in the pulping production line has the following characteristics due to its strict production process.
The starting torque is large, the wood chip refiner needs to overcome the moment of inertia and friction torque when starting, and needs enough torque when starting.
Acceleration/deceleration time is short and the acceleration time does not exceed 60S. If no braking unit and braking resistor are configured, the deceleration time should not exceed 30s.
The motor needs ultra-fundamental frequency operation. In order to increase the production efficiency, the motor needs to operate above the fundamental frequency under special circumstances.
The frequency inverter is required to have strong ability to resist power grid fluctuations. Since factory power uses waste generated in pulp production, all power grids fluctuate. In order to ensure the normal operation of the production line, the anti-grid power fluctuation of all inverters can reach 15%.
With high reliability, once the failure of the wood chip refiner, the entire production line must be stopped, causing great economic losses to the factory. All the factories require the inverter to run for 24 hours at least for at least 3 months.
Fourth, inverter debugging
Since the wood chip refiner needs to output 2 times of the rated torque of the motor during start-up, and at the same time it guarantees that the frequency converter is not over-current, the frequency converter uses vector open-loop control mode; it has the following features:
The weak magnetic function of the inverter enables the motor to operate at 50HZ or more
Enables the flux braking function of Goodrive300 inverter, so that part of the energy is consumed on the motor during deceleration to meet the deceleration time requirements.
Enable overvoltage stall and overcurrent protection functions of Goodrive300 inverter to ensure that the inverter will not affect the production during acceleration and deceleration.
Because Goodrive300 inverters can adapt to 15% of the grid fluctuations, they can adapt to the grid conditions of the plant without failure
V. Conclusion
The production line has been in trouble-free production for one year since it was put into operation, which proves that the Invitrogen Goodrive300 inverter can fully meet the production process requirements of the wood pulp refiner of the pulp production line in terms of performance and reliability. Inventive GoodDrive300 inverter has won very good recognition in this enterprise. .
About Infinity: Invicta.
Inventronics, established in 2002, is committed to becoming a world-leading and respected supplier of products and services in the fields of electric drive, industrial control, and new energy. In 2010, it was listed on the A-share stock exchange of the Shenzhen Stock Exchange with stock code: 002334. Inventronics is a key high-tech enterprise of the National Torch Plan. Currently, it has 11 holding subsidiaries and is based on key technologies such as power electronics, automatic control, motor control, energy saving and environmental protection, internet of things, and informatization. Its main products include high and medium , Low-voltage inverters, elevator intelligent overall machine, servo system, PLC, HMI, motor and electric spindle, SVG, UPS, photovoltaic inverter, etc. Inventronic has more than 1,600 employees and 4 large-scale production bases. Its marketing network covers more than 60 countries and regions in China and overseas.
About Aix:
Inner Mongolia Aix Electromechanical Equipment Co., Ltd. is one of the largest frequency converter distribution companies in Inner Mongolia. It is the only designated agent of many well-known domestic and foreign brands in Inner Mongolia.
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Shenzhen GuanChen Electronics Co., Ltd. , https://www.gcneotech.com