| In response to the energy-saving and efficiency increasing needs of a sugar company in Guangxi, especially the need to improve the sugar yield and power saving rate of the press, the T600 series 560kw parallel scheme frequency converter was used to carry out the technical transformation of five presses in a sugar factory. After transformation, the press system operates stably and reliably; According to the actual measurement, the total recovery rate of the sugar factory was increased by 0.2%, and the power consumption per ton of sugarcane was reduced by 2 degrees. It is estimated that the investment can be recovered in 1-2 pressing seasons, and good economic benefits have been achieved. █ overview In the sugar industry, a large number of fans and water pumps have been transformed by frequency conversion, and remarkable energy-saving effects have been achieved. As an important equipment in the sugar factory, the press has been running at a constant speed in the traditional way. According to the sugar production process, energy-saving transformation can greatly improve the production efficiency of the enterprise. █ process analysis The yield of the press is one of the main factors affecting the total sugar yield. If the yield of the press increases by 1%, the total recovery rate increases by 0.88% - 0.92%. The factors affecting the extraction rate mainly include the following reasons: 1. When the fiber components in sucrose are pressed and leave the outlet of the press, they expand again. At this time, the pressed fiber will absorb part of the pressed juice at the outlet with its own expansion. At the same time, affected by the efficiency of the press, the sugar in sugarcane cannot be squeezed out completely, which forms the sugar loss in bagasse. 2. The crushing degree and shape of sugarcane are the premise to ensure the extraction of the first press. Sugarcane has good crushing degree, sugarcane juice is easy to press out, and the exudation effect is improved. 3. Reducing the moisture content of bagasse is the guarantee to improve the extraction. 4. It is very important to ensure the uniform thickness of sugarcane layer transported from the shredder to improve the extraction rate. If the sugarcane layer is too thick and the crushing is not complete, bagasse will be wasted; If the sugarcane layer is too thin, the sugarcane layer cannot be pressed dry, and the moisture content of bagasse is too high, which will affect the extraction rate. 5. In the later stage of the pressing season, the wear of the press roll is becoming more and more serious, which leads to the expansion of the gap of the press roll and the decrease of the extraction rate. To sum up, because the speed of the press is not adjustable, the thickness of the sugarcane layer transported from the shredder will not meet the requirements for about 10% of the time, which will make the average extraction rate of sugarcane juice lower than 95.4%. The lower the extraction rate, the greater the loss of sugarcane juice, resulting in lower yield. If the speed of the press can be adjusted, when the backwardness of the sugarcane layer is not enough, press the sugarcane layer after it reaches the normal thickness by reducing the motor speed of the press. In this way, the press will be more sufficient, and the average extraction rate will be increased by more than 0.2%. At the same time, due to the reduction of the speed, the current will drop, so as to achieve the purpose of energy saving and power saving. █ overview of the transformation of a sugar company in Guangxi A sugar company in Guangxi is a sugar manufacturing enterprise ranking at the top of the national sugar processing industry. Through technological transformation in recent years, its annual production capacity has reached 10000 tons / day, and its annual output can reach more than 1.6 million tons. The parameters of the sugar crusher for this technical transformation are shown in the table below: Serial number Rated voltage Rated power Rated current Rated speed Speed regulation ratio one 380V 380kW 699.2A 734r/min four point one seven two 380V 380kW 699.2A 734r/min four point one seven three 380V 380kW 715A 737r/min four point one seven four 380V 380kW 715A 737r/min four point one seven five 380V 400kW 748A 742r/min four Parallel plan In this reconstruction project, in view of the large power of the driving motor of the press, using the "parallel" model newly developed by INVT company (that is, using two low-power converters to drive a high-power motor together) has the following advantages: 1、 No separate structural design is required; 2、 It can greatly improve the delivery speed; 3、 Easy control of quality; 4、 High cost performance; By sharing the control module and output synthetic reactor, the output power balance of the two inverters is ensured. Reconstruction scheme In this transformation, as mentioned above, a total of five presses need to be transformed. Six T600 560kw parallel frequency converters of the company are selected, five for use and one for standby. The system wiring diagram is as follows: If any of the five frequency converters fails, put the standby machine into operation to ensure the normal production of the factory. The frequency converter sets the operating frequency and sets the minimum frequency of 35Hz in the following ways: Nuclear scale signal feedback full-automatic control: the sugarcane layer is measured by the nuclear scale and then sent to the press by the conveyor belt for pressing. The nuclear scale outputs 0~5v signal to the frequency converter, which adjusts the speed of the conveyor belt according to this signal to ensure the uniformity of sugarcane quantity. On the basis of the above driven control system, the signal of the nuclear scale is fed back to the frequency converter, and the frequency converter will adjust the speed of the press according to the amount of sugarcane. The large signal of the nuclear scale indicates that the sugarcane layer is thick, and the frequency converter will increase the speed of the motor; The small signal of the nuclear scale indicates that the sugarcane layer is thin, and the frequency converter will reduce the speed of the motor, so as to ensure the uniformity of the sugarcane layer thickness and help to improve the extraction rate. Constant current automatic control: according to the analysis of the production process, in order to improve the extraction rate, it is very important to ensure the thickness of the sugarcane layer, that is to say, the smaller the fluctuation range of the motor current, the better. On the basis of the above driven system, the hall sensor is added to detect the actual current of the motor as the feedback signal of the frequency converter, which controls the motor speed according to the feedback signal. If the sugarcane layer is too thick, the current of the motor becomes larger, and the frequency converter will increase the speed of the motor, so that the sugarcane layer can be squeezed as soon as possible; If the sugarcane layer is too thin, the current of the motor becomes smaller, and the frequency converter will reduce the speed of the motor, so as to press the sugarcane layer as thoroughly as possible. In this way, the motor current always fluctuates in a small range, so as to ensure the uniformity of sugarcane layer thickness and help to improve the extraction rate. ■ conclusion The crusher of a sugar factory in Guangxi was reformed, and good economic benefits were obtained. Through this transformation, it is also verified again that the parallel scheme has excellent cost performance in the frequency conversion transformation of high-power motors. It provides a more economical and reliable choice for sugar factories and other industries that use high-power motors for technical transformation. | |||||||
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