Realized by using PLC and frequency converter to retrofit design - 1250 electric control system of centrifuge

1。 Preface

1250 centrifuge is vertical scraper discharge automatic filtering centrifuge, is mainly used for solid phase for granular suspended solid liquid separation materials, and can also be used for solid liquid separation fibrous materials. Mineral, environmental protection, widely used in pharmaceutical, chemical and other industries. At present most of the centrifuge are still controlled by relay, adopts step speed regulation, centrifuge speed setting of the single, equipment failure rate is higher, the production efficiency is low. In order to overcome these problems, we are pharmaceutical factory 1250 technical renovation, electric control system of centrifuge adopts PLC and frequency converter speed control, the system is a high degree of automation, good stability, reliable operation, has been successfully applied in several pharmaceutical companies.

2。 System principle

centrifuge working principle is to stay by the feeding tube into the high-speed centrifuge separation material inside the drum, centrifuge force field, the material of filter cloth ( Mesh) Realize filtering, liquid through a liquid discharge tube, solid phase intercept in the drum, with drum filter cake in charge stipulated in the machine, stop charging, the filter cake washing, washing liquid filter out at the same time, meet the requirements of separation, centrifuge speed, scraper device, blowing the filter cake, to complete a working cycle. Figure 1 is 1250 centrifuges structure.

the centrifuge process: 1) Feed: when the inverter speed reaches 20 hz, first open the feed valve, check valve, when the detected material layer is full, close the feed valve and time delay 10 s, material layer with signals disappear again open the feed valve for executing the above action 2 times. 2) Centrifugal: when the third material full signal, inlet valve inverter up to 50 hz close to high-speed separation, centrifugal time set by the touch screen, frequency converter speed down to 40 hz after their time. 3) Clean dry: open the purge valve cleaning, cleaning time, pause time and washing time separation of drug varieties set by touch screen. After the completion of the cleaning process in the process of dry, inverter frequency 50 hz, dry time set by touch screen. Time to enter into the state of discharge. 4) After discharge, dry material layer thickness, scraper with subsection timing rotation discharge, namely blade rotation ( Time can be set) - >

stop for 2 seconds to scraper ( Drop height can be set) , repeat the above action, until finally a scraper descend to lower limit sensor movement, and then rise to the top is the highest limit stop.

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to shake preventing interference signal, the input point X11, X12, X13, X14, X15, X16, X17, X20 respectively by four isolated grid connected to the PLC controller input. 2 software design

by using programming software, programming MELSECMEDOC professional software package, which is based on personal computer, is suitable for mitsubishi PLC user programming and monitoring, SC - 09 rs232 / RS422 interface with PLC programming port is linked together, can use ladder diagram or instruction programming. This ladder diagram procedure of PLC controller control system require the use of the STL and SET step by step instructions. Mainly include initialization setting, feeding, separating, cleaning, dry control procedures, automatic control, etc. Programming for safety protection are: speed detection, vibration protection, open cover protection, motor overload overheat protection, scraper rotating, lifting machinery electrical dual control, scraper and drum linkage locking. Program flow chart 4 shows.

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4. Conclusion

the system several field operation, the result is satisfactory the indicators meet the technical requirements. System startup is smooth, adjustable separation factor, operation simple and convenient, since the reform in operation, stable running convenient speed adjustment, free maintenance, for the operators to create a working environment with high efficiency, achieve 1250 centrifuges advanced control technology.

editor: gt

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