Abstract: This paper analyzes the production process of alumina and the requirements for frequency converters. It also introduces the application of Inventronics Goodrive800 inverter in alumina production line based on the ControlNet redundant communication network, which greatly reduces the production cost and production of alumina enterprises. The failure rate of equipment has produced greater economic, social and environmental benefits.
Keywords: Goodrive 800 ControlNet Alumina Redundant Communication Inverter
As alumina production puts high demands on the frequency converter, when design institutes do design, they all use imported frequency converters such as ABB, Siemens, Schneider, and AB. The first domestic 800,000-ton alumina production line for the first time adopts the domestic Invensys Goodrive800 series inverter, and the network adopts ControlNet dual-network redundant communication control scheme. On-site operation shows that the Goodrive800 inverter operates stably and successfully replaces the imported brand inverter. More cost-effective.
2 production process and inverter requirements
2.1 Alumina production process
The production of qualified alumina from bauxite ore requires several major production processes such as raw materials, dissolution, settling, decomposition, and roasting, and is organized into several major workshops as raw materials, dissolution, settling, decomposition, and roasting according to the order of the process flow. To make full use of the mother liquor, set up an evaporation process workshop again. The raw material workshop is used to prepare raw ore pulp that meets the requirements for particle size and composition ratio; the dissolution workshop provides high-temperature and high-pressure environment for raw ore slurry through multi-stage preheating casing and pressure cooker, and ensures sufficient dissolution time for the original The alumina component in the slurry dissolves into the sodium aluminate solution. The sedimentation workshop separates the crude liquid in the slurry and the red mud consisting of various impurities through settling and multiple reverse washing. The separated crude liquid is filtered by a leaf filter to obtain semen, and then sent to decomposition. The workshop and the seed crystals are mixed, and each of the decomposition tanks is gradually reduced in temperature and agitated to fully analyze the aluminum hydroxide. The precipitated aluminum hydroxide slurry is classified and then the fine material is passed through the seed filtration to prepare seed crystals. The rough material is sent to the roasting workshop and filtered. High-temperature roasting is performed to obtain finished product alumina. The evaporation plant is used to concentrate the circulating mother liquor to remove excess moisture entering the mother liquor during the process to reach the mother liquor concentration required by the process.
2.2 Alumina Production Requirements for Frequency Converters
The entire alumina production process is carried by various pumps with different functions such as slurry pumps, feed pumps, discharge pumps, mother liquor pumps, alkali pumps, and circulation pumps. In the production process, the control of the temperature and pressure of the materials and reaction vessels, the flow rate of the ingredients and other indicators are very strict; at the same time, in order to ensure the continuous operation of the continuous operation of the equipment such as the disintegration tank stirring, the high temperature and high pressure of the diaphragm pump and the pressure cooker are required. High-alkali equipment and roasting system The safe operation of flammable and explosive equipment requires that the various pumps that carry the material be able to operate at variable speed under the control of the DCS. The alumina production process is more complicated, the production environment is poor, the temperature is high, and the dust is large. The main requirements for the inverter are:
1) The working medium of the slurry pump, feed pump, discharge pump, etc. is a very viscous slurry with load characteristics close to constant torque load characteristics. For some reason, the production will pause for a short time, and the viscous slurry will cause sedimentation. When the resumption of production is started again, the starting torque of these pumps is very large. Therefore, the inverter must have sufficient starting torque and high overload capacity.
2) The alumina production line occupies a large area. Its electrical control equipment and frequency converters are installed in the power distribution room. The distance between most of the motors and the frequency converter is 100-300 meters, and the output of the frequency converter is required to be connected to 100. -300 meters of cable can work normally.
3) The output of the inverter contains high-order harmonics, and the number of inverters used in the field is large. Harmonics must be considered to interfere with the DCS control system and on-site control instruments. The harmonic content of the output of the inverter must be low, which is lower than the national standard GB12668. -2.2002, the harmonic content required by GB12668-3.2003.
4) The production of alumina has continuity. The production of aluminum oxide in the entire production line will cause great losses due to the failure of one equipment. Therefore, the reliability of the inverter is extremely high.
3Goodrive800 inverter technical characteristics
1) The functional safety concept with standard STO (Safe Torque Off) and SS1 (Safe Stop 1) complies with the latest EU Machinery Directive 2006/42/EC
2) Supports various buses such as Profibus-DP/Can/ControlNET/DeviceNet
3) Modular design of frequency converter unit, high power density, small cabinet size
4) The input and output of the inverter unit is designed to facilitate the parallel system to form a large system
5) Inverter unit moving roller sliding structure design facilitates system maintenance
6) Rectifier and inverter power units are compatible with each other, reducing post-maintenance costs
7) The inverter unit is controlled by the control unit through optical fiber communication. The control unit is designed in an independent and modular manner, which facilitates the system to be a cabinet, can be distributedly installed, strong and weak electrical isolation, and has strong anti-interference ability.
8) The side harmonics of the four-quadrant rectified energy feedback is â‰¤ 5% and the interference to the grid is small
9) The bus voltage is adjustable. When the voltage of the power grid fluctuates, the output voltage can be stabilized.
10) Superior vector control performance, large starting torque, closed-loop vector starting torque up to 200% rated torque
4ControlNet redundant network introduction
ControlNet is a real-time fieldbus network oriented to the control layer launched in recent years. It provides time-critical I/O data and message data on the same physical layer media link, including program upload/download, configuration data and end-to-end. End-to-end messaging and other communication support is a highly deterministic, repeatable high-speed control and data acquisition network. I/O performance and end-to-end communication performance are significantly higher than traditional networks.
ControlNet allows multiple controllers to coexist on the same link to support input data or end-to-end multiplexing, which greatly reduces the amount of traffic on the network and improves network efficiency and network performance. ControlNet can anticipate when the data can reliably transmit to the target's ability, while the data's transmission time is not affected by the network node's add/delete condition or the network's busy condition and maintain the constant ability. In practical applications, the selective setting of planned I/O grouping or interlocking time during network configuration can be further guaranteed.
ControlNet has the advantages of optional media redundancy and intrinsic security. The installation and maintenance are simple. The nodes on the network are in a peer-to-peer position and can access the network from any node. The topology (bus type, tree type, star type, etc.) and Media selection (coaxial cable, fiber optics, and others) can be flexibly selected.
5Goodrive800 Inverter Field Application
5.1 Frequency Converter Selection
A domestic production company newly produces 800,000 tons of alumina smelting project annually. After selection, it finally selects a new generation of high-performance, Goodrive 800 engineering vector control inverter with rotor field orientation developed by Shenzhen Inventronics Co., Ltd. independently. Each step of the production process provides frequency control (power from 15kW to 800kW), a total of 144 installations.
5.2 Control Layer and Device Layer Network Topology
The control layer of the electrical part of the entire production line adopts the AB company DCS system and configures the ControlNet dual-network redundant communication network to control the equipment layer nodes of the Goodrive800 inverter. The system topology (partial) is as follows:
5.3 Frequency Converter Selection Configuration
1) For the requirements of alumina production on the inverter, the torque of the selected Goodrive800 inverter can be up to 200% at 1Hz without closed-loop operation.
2) Considering the overload factor, the actual capacity of the motor will increase by one gear, and the capacity of the inverter will also increase.
3) Considering that more frequency converters are used in the entire production line, input reactors and input filters are installed on the input side of the inverter to ensure that it will not interfere with the calculation control system and digital instruments under any circumstances.
4) Considering that the length of the output cable increases, the distributed capacitance and the distributed inductance also increase accordingly, and for a certain harmonic may cause oscillation or form a standing wave, which will seriously affect the operation of the motor. Install output reactor or add output filter on the output side of the inverter to stabilize the dU/dt spike output from the inverter.
5.4 Inverter Electrical Schematic and Function Settings
5.4.1 Gas schematic
5.4.2 Inverter Control Box Terminal Functions
Control box DC24V power supply
Digital input: Forward operation
Digital input: command to switch to communication
Digital input: external fault input
Digital signal common;
Relay output: running
Relay output: inverter failure
Inverter and DCS communication connection
Connect to ControlNet redundant network via T-type head
5.4.3 Frequency Converter Function Code Setting Table
Speed â€‹â€‹control mode
Space Voltage Vector Control Mode
Run the instruction channel
Terminal operation instruction channel
Communication operation instruction communication channel selection
ControlNet communication channel
A frequency command selection
ControlNet communication settings
Acceleration time 1
According to the site process settings
Deceleration time 1
According to the site process settings
Operation direction selection
Reverse rotation prohibited
Frequency converter application
Set light and heavy overload applications based on specific equipment
Acceleration and deceleration options
Belt Selector S Curve Type
Induction motor 1 rated power
Motor nameplate data
Induction motor 1 rated frequency
Motor nameplate data
Asynchronous motor 1 rated speed
Motor nameplate data
Asynchronous motor 1 rated voltage
Motor nameplate data
Induction motor 1 rated current
Motor nameplate data
S1 terminal function selection
S2 terminal function selection
Command to switch to communication
S3 terminal function selection
External fault input
S1 terminal closing delay time
Run the cooling fan first and then run the main motor (set according to customer requirements)
Relay RO1 output selection
Relay RO2 output selection
Output terminal polarity selection
ControlNet module address
Actually set a unique value according to the site
Terminal input status
ControlNet input length
DCS configuration communication card input length, set according to DCS requirements
ControlNet output length
DCS configuration communication card output length, set according to DCS requirements
The principle of inverter control in each process is basically the same. There are some differences in the functional settings between the different sections and processes. Only the parameters of the Goodrive800 250kW inverter's function settings are listed in the table for reference only.
At present, Goodrive 800 inverters have been successfully put into operation for more than one year in alumina production lines. The high reliability of Inventronics inverters has been fully verified and compared with imported inverters. Invincible Goodrive800 inverter has successfully replaced the imported brand inverter in the alumina industry, and it is more cost-effective and deeply satisfied with users.
 Goodrive800 Series Inverter Software Manual. Shenzhen Inventronics Co., Ltd.
 Goodrive800 Series Drive Converter Product Manual. Shenzhen Inventronics Co., Ltd.
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