light industry

一、preface
Non-ferrous metals industry on the inverter performance and stability is very high. ECF300 inverter in the success of a large area of the industry use, Yi Fei record of inverter technology level has been greatly improved. In practical application, ECF300 inverter and foreign inverters compared favorably, in alumina industry successfully replaced the foreign brand inverter, outstanding cost-effective and environmental tolerance than the foreign brand inverter.

二、Alumina production process
Bauxite ore production from a qualified alumina are required after raw materials, dissolving, settlement, decomposition and roasting a few production process, according to the process of order organization for raw materials, dissolving, settlement, decomposition and roasting workshop. In order to make full use of the mother liquor, then set up a workshop of evaporation process. Workshop of raw materials used for preparing particle size, the ratio of composition index are in accordance with the requirements of the original pulp; dissolution workshop raw pulp provides high temperature alumina ingredients dissolution to sodium aluminate solution through multilevel preheating casing and autoclave. Settlement workshops through the settlement and multiple reverse washing, the material in the pulp thick liquid and attached to alkali and various impurities consisting of red mud separation, separation of coarse liquid after leaf filter filtration of semen, sending to the workshop with the seed mixture decomposition, step by step into the the decomposing tank temperature, stirring, to supplement the analysis of aluminum hydroxide, precipitated aluminium hydroxide slurry after grading fine material into seed filtering of producing seed, coarse material send roasting workshop after filtering for high temperature roasting, the final product is prepared alumina. Evaporation plant for the circulating mother liquor was concentrated with, to remove into excess moisture in the mother liquor in the process, to the technical requirements of the concentration of the mother liquor.

三、Requirements for the production of aluminum oxide for inverter
The alumina production process of materials transported by the pump, feeding pump, a bear material pump, liquid pump, a solution pump, circulating pump a wide variety of pump. Is very strict control of the production process, the temperature of the material and the reaction container, pressure, material flow and index. Meanwhile, in order to ensure continuous operation of the decomposition trough stirring requirements of uninterrupted operation of the equipment, as well as the pressure diaphragm pump, boiler high temperature, high pressure, high alkali equipment and roasting system inflammable or explosive equipment safe operation, to transport materials of all kinds of pumps can in DCS control variable speed operation. Alumina production process is more complex, the production environment is poor, high temperature, dust, the main requirements of the inverter:
1, pump, feed pump, feed pump, such as the working medium is very viscous slurry and the load characteristic nearly constant torque load characteristics. Due to some reason, the production of short pause, viscous slurry will settlement, to resume production once again starting, the pump starting torque is very large. Therefore, the inverter has large enough starting torque and high overload capacity.
2, alumina production line covers an area of large, its electrical control equipment and frequency converter are installed in power distribution room, most of the motor and inverter distance in the 100 to 300 meters, the inverter output connected to 100 to 300 meters of cable can work normally.
3, the output of the inverter harmonics and number of field frequency converter, must consider harmonic of DCS control system and field control for the interference of instrument, the frequency of output harmonic content requirements is low, lower than the national standard harmonic content GB12668-2.2002, GB12668-3.2003 required.
4, alumina production with continuity, the production process due to a device failure caused by the whole line of production, will bring great loss, therefore, the high reliability of the inverter.

四、Application of ECF300 series inverter in alumina production line
From the visible, the production of alumina on the inverter is very high requirements, Aluminum Magnesium Design Institute in the design, there is no case in the field of selection of ABB, Shi resistant, SIEMENS, AB and other foreign inverter. In recent years, domestic inverter technology has made great progress, especially is Yi a fly vector control inverter ECF300 series developed, greatly enhance the technique level and the application scope of domestic inverter. Its technical performance has reached the advanced level of foreign inverter, coupled with the improvement of process technology and management level, fully meet the requirements of alumina production line, high performance, high reliability and other performance and reliability requirements. Compared with the foreign frequency converter, the price is lower, and it has a great advantage in the competition with the foreign inverter.
ECF300 series inverter for Yi Chong fly converter manufacturing company independently developed a new generation of low noise, high performance, high reliability, powerful current vector inverter by the rotor field oriented vector control method, realized the high precision control of the motor. The operating panel with programming, operation, replication parameters, heat dial in function, greatly facilitate the operation personnel of parameters modification (only for a frequency converter parameter setting, other can were replication parameters, reduce the debugging workload in the process of), velocity given by switching the terminal, reducing the external cumbersome wires. When the power is off, the bus voltage is controlled to realize uninterrupted operation; the carrier frequency can be adjusted automatically according to the load characteristic and the environment temperature.
For alumina production the main requirements of the inverter, high performance ECF300 without speed sensor less vector control inverter 1Hz torque up to 180%, without the need to run a loop; overload factors into account, in the practical application capacity motor will increase the file, inverter capacity is increased; inverter ECF300 using a variety of harmonic suppression technology, total harmonic content has been lower than the national standard. Consideration to the entire production line using the inverter more, also need to add input reactor and the input filter at the input side of the inverter, guarantee in any case are not the calculation of digital instrument and control system caused by interference; frequency converter output cable distance limitations of general within 50 meters, increase the length of the output cable, distribution capacitance and inductance is also a corresponding increase, possibly can cause shock or forming a standing wave to the harmonic, which will seriously affect the motor operation. Design of frequency control system in the output side of the converter installation of reactor output or output filter and stabilize the output of inverter Du / dt spikes.
A Sino foreign joint venture alumina production enterprises, the alumina production in 150 million tons, according to the requirements of production process selected Yi Chong Fei converter manufacturing Co., Ltd. developed a new generation of low noise, high performance, the non speed sensor control ECF300 vector control inverter, every process of the production process to provide frequency control (power from 22KW to 450KW) and total installation and use and 82, the specific use of the station as shown in the following table:

Frequency converter power（kW）	Device name
450	Seed pump
250	Dilution pump, discharge pump, feed pump, evaporator feed pump, evaporator discharge pump, pump, single pole double suction centrifugal pump, semen pump
220	Mud pump, over feed pump
200	Slurry pump, feeding pump, liquid pump, the evaporation of crude liquid pump
160	The liquid storage tank / alkali lye pump, qualified qualified lye pump / liquor pump, horizontal circulating pump
132	Water pump, slurry pump, slurry pump
110	Overflow pump, over feed pump, submerged pump, intermediate cooling pump
90	Desilication under air pressure distribution room circulation pump, water pump, settlement mother liquid pump
55	Strong and weak filtrate pump pump, liquid pump filter
45	Hot water pump
37	Salt underflow pump
22	Salt underflow pump

五、Concluding remarks
ECF300 inverter in alumina production line installation to run to now more than a year, there has not been any failure, the reliability rate of 100%, compared with foreign inverter favorably. ECF300 in the alumina industry has successfully replaced the foreign brand inverter, won the satisfaction of users.