CN2624147Y

CN2624147Y - Automatic control device for fused magnesia furnace

Info

Publication number: CN2624147Y
Application number: CN 03212158
Authority: CN
Inventors: 吴新军; 王良润; 官红子
Original assignee: KEXIN Co ANSHAN SCIENCE-TECHNOLOGY UNIV
Current assignee: KEXIN Co ANSHAN SCIENCE-TECHNOLOGY UNIV
Priority date: 2003-03-26
Filing date: 2003-03-26
Publication date: 2004-07-07
Anticipated expiration: 2013-03-26

Abstract

The utility model discloses an electrically fused magnesium furnace automatic control equipment, adopting the programmable controller as the main controlling unit, the no touch switch as the actuator, realizing variously and reliably automatic control. The electrically fused magnesium furnace automatic control equipment comprises an upper computer, a printer, a programmable controller PLC, an operating board, a current sampling and passage switching part and an actuator. The utility model has histograms of tele-monitoring, opening/closing furnace controlling, manual/automatic change-over, current given value setting and actual time current value and has functions such as displaying, the digital quantity,. Making a statistics to the electric quantity of each furnace, timing, automatically discharging, and fault self diagnosis, etc. The utility model has advantages of steady and reliable field operating, rapid response speed, long service time, no noise, small maintaining quantity and low running cost. 97 percent and 98 percent grade proportion of the electrically fused magnesium product is increased and the airtight is small. The utility model also can make the most of the capacity of the furnace transformer to increase the output. The three phase current control has good proportionality, the three carbon electrodes are consumed congruously, saving the electric energy and the carbon electrode.

Description

The electric melting magnesium furnace automaton

Technical field the utility model relates to the electric furnace automaton, especially a kind of electric melting magnesium furnace automaton.

Background technology is used to smelt the electric melting magnesium furnace of electric-melting magnesium and need controls.Present control mode adopts manual control basically, and shortcoming is that the three-phase current fluctuation is big, uneven, response speed is slow, control accuracy is low.Circuit easily trips during big electric current; Little electric current is seen stove, can cause smelt insufficient, power consumption and yielding poorly.The output of product and quality directly are subjected to operating personnel's influence.Patent ZL00252425.2 discloses " a kind of fused magnesia smelting Power Regulation power supply ", can only control the power output of power supply, can not control to adjust other important parameters in the smelting process.At above drawback, need a kind of multiple functional, electric melting magnesium furnace automaton that control accuracy is high, reliable and stable.

Utility model content the utility model adopts Programmable Logic Controller as main control unit, and noncontacting switch is an executing agency, and a kind of electric melting magnesium furnace automaton of automatic control mode is provided, and reaches energy-conservation, volume increase, improves the purpose of product quality.

For achieving the above object, design of the present utility model is as follows:

The electric melting magnesium furnace automaton comprises: the host computer that carries out communication by RS485/RS232 serial communication converter and PLC; Be used to print the printer of time data of electric furnace electric weight, electric furnace tripping operation number of times, the super upper limit of each stove electric current of each order of classes or grades at school; Write the Programmable Logic Controller PLC of control program; Form operating desk by air switch, relay, buzzer, contactor, noncontacting switch, analog quantity switch boards, current sensor, Switching Power Supply and one group of PLC; Use the Hall current transmitter, undertaken that passage switches and the current sample and the passage switching part that constitute by sampling plate of PLC control; The noncontacting switch that adopts the controllable silicon inverse parallel to form is controlled the executing agency of the rotating of motor.Annexation between host computer, printer, Programmable Logic Controller PLC, operating desk, current sample, passage switching, the executing agency is as follows: host computer links to each other with printer with print cable by LPT, adopt the parallel communication swap data, serial port links to each other with Programmable Logic Controller by RS232/485 serial communication converter simultaneously, adopts the serial communication swap data.Programmable Logic Controller adopts the switching value input/output port to link to each other with operating desk, accepts the various instructions of operating desk, and the executing agency of control operation platform; Programmable Logic Controller is connected swap data by switching value input/output port and analog quantity mouth with current sample and passage switching part simultaneously.Real-time switch sampling passage, sampling obtains the electric current of electric furnace.

The utility model its significant effect of comparing with existing electric melting magnesium furnace control mode is:

Device has remote monitoring, opens/blowing out control, manual conversion, electric current set-point are provided with, the histogram and the digital quantity of real-time current value show, the functions such as electric weight statistics of each stove;

Programmable Logic Controller PLC makes sampling, the computing of electric melting magnesium furnace three-phase current, the control noncontacting switch promotes or the decline electrode, and the three-phase actual current and the setting value of regulating electric furnace are consistent, make three-phase current keep balance, and have functions such as timing, automatic vent;

The on-the-spot stable and reliable operation of electric melting magnesium furnace central control device, response speed is fast, the life-span is long, noiseless, maintenance is little, operating cost is low.Compare with the product of manual control stove production, 97%, 98% grade proportion in the electric-melting magnesium product increases, and 96% grade proportion descends, and is airtight little.Also can make full use of the capacity of furnace transformer, productivity gain under the same conditions, uses this equipment than manually control volume increase 15%;

It is harmonious good that three-phase current is controlled, and three carbon electrodes consume unanimity, saves energy and carbon electrode;

Device has fault self-diagnosis function, and sound and light alarm is arranged during fault, the automatic trip of circuit overcurrent, over current of motor, open-phase protection.

Description of drawings Fig. 1 electric melting magnesium furnace automaton structured flowchart; Fig. 2 is device layout figure in operating desk and the switch board; Fig. 3 is a current sample commutation circuit schematic diagram; Fig. 4 is a PLC control circuit schematic diagram; Fig. 5 is the control program flow chart.

The specific embodiment further describes embodiment of the present utility model below in conjunction with accompanying drawing.

Shown in Figure 1, host computer is used for remote monitoring, carries out communication by RS485/RS232 serial communication converter and PLC, finish opening/blowing out is controlled, manual conversion, the electric current set-point is provided with, and the histogram of real-time current value and digital quantity show, functions such as the electric weight statistics of each stove; Printer is mainly used in the electric furnace electric weight of printing each order of classes or grades at school, electric furnace tripping operation number of times, the data such as time of the super upper limit of each stove electric current; Programmable Logic Controller PLC mainly finishes sampling, the computing of four electric furnace three-phase currents, the control noncontacting switch, promote or the decline electrode, the three-phase actual current and the setting value of regulating electric furnace are consistent, make three-phase current keep balance, and finish timing, automatic vent, open/blowing out, function such as manual order.

Shown in Figure 2, in operating desk and device switch board, five air switches, ten relays, two buzzers, a contactor, six noncontacting switches, an analog quantity switch boards, three groups of current sensors, two Switching Power Supplies and one group of PLC are set.

Shown in Figure 3, current sample and passage switching part, current sample uses the Hall current transmitter, and response speed is fast, and passage switches by sampling plate of PLC control to be finished.With PLC transistor output point, after level conversion, control three multiway analog switch AD7501, simultaneously A, the B of a stove, the mould that the C three-phase current switches to PLC are simultaneously gone on the module.

Executing agency, the size of control electric furnace three-phase current promotes or the decline electrode by motor, and control electrode and electric-melting magnesium are conducted electricity the degree of depth that contacts of liquation.Because adopt the crawl control mode, motor action is quite frequent, so the noncontacting switch that the rotating of motor control adopts the controllable silicon inverse parallel to form is finished.

The type selecting of Programmable Logic Controller PLC and configuration: install that 16 of required switching value input points, 32 of switching value output points, analog quantity import 3 tunnel, one of RS485/RS232 serial communication converter.Analog quantity in the control algolithm is calculated needs PLC that stronger mathematical operational ability is arranged, can the computing floating number.With the communication need of host computer, PLC has the free interface communication of open user-programmable, selects the S7-200 series of PLC of Siemens.

Shown in Figure 4, the configuration of PLC is as follows: three of one, 8 switching value output modules of one, 8 switching input modules of host module S7214, one of three tunnel analog quantity input module.

Control program is write and control algolithm: the program storage 4K word of the main frame S7214 of Programmable Logic Controller, the user data memory size is the 2.5K word, needs to gather, the electric current of computing, four stoves of control and finish exchanges data with host computer.Adopt common linear programming method, user program memory and user data memory are all not enough.Therefore used subprogram during coding in a large number.The programming of four stove identical functions is become subprogram, come call subroutine and variable in the subprogram is composed different values by conditions different in main program.As the current acquisition submodule, filtering algorithm submodule, departure calculating sub module, control algolithm submodule etc.Adopt the serial interrupt mode to finish with the communication part of host computer, the reception of data and transmission are all finished in interruption.

PLC calculates the departure of each phase current of every electric furnace and setting value by gathering the electric current of each stove, and according to the size of departure, polarity (overgauge or minus deviation) is determined lifting or the electrode that descends, and calculates the time of action, the distance that control electrode moves.Owing to for the triangle discharge, move a wherein phase between three-phase electrode, can influence other biphase current, only move a phase electrode or mobile simultaneously two-phase electrode generally speaking, have only when three-phase current surpasses upper current limit simultaneously just mobile simultaneously three-phase electrode.Concrete control algolithm is as follows:

When three-phase current surpasses upper current limit simultaneously, mobile simultaneously three-phase electrode;

When the departure of three-phase current and setting value surpasses given departure simultaneously, two electrodes that mobile simultaneously departure is bigger;

When the departure of biphase current and set-point surpasses given departure simultaneously, if departure just is being all or is being all when bearing, an electrode of mobile departure maximum, otherwise mobile deviation is positive electrode;

When the departure of having only a phase current and set-point surpasses given departure, mobile corresponding electrode;

When three-phase current during simultaneously less than lower current limit, a phase electrode of the mobile departure maximum in time-delay back.

Program flow chart is seen accompanying drawing 5.

Claims

1, a kind of electric melting magnesium furnace automaton is characterized in that device comprises: the host computer that carries out communication by RS485/RS232 serial communication converter and PLC; Be used to print the printer of time data of electric furnace electric weight, electric furnace tripping operation number of times, the super upper limit of each stove electric current of each order of classes or grades at school; Write the Programmable Logic Controller PLC of control program; Form operating desk by air switch, relay, buzzer, contactor, noncontacting switch, analog quantity switch boards, current sensor, Switching Power Supply and one group of PLC; Use the Hall current transmitter, undertaken that passage switches and the current sample and the passage switching part that constitute by sampling plate of PLC control; The noncontacting switch that adopts the controllable silicon inverse parallel to form is controlled the executing agency of the rotating of motor, annexation between host computer, printer, Programmable Logic Controller PLC, operating desk, current sample, passage switching, the executing agency is as follows: host computer links to each other with printer with print cable by LPT, adopt the parallel communication swap data, serial port links to each other with Programmable Logic Controller by RS232/485 serial communication converter simultaneously; Programmable Logic Controller adopts the switching value input/output port to link to each other with operating desk, and the executing agency of control operation platform; Programmable Logic Controller is connected with current sample and passage switching part by switching value input/output port and analog quantity mouth simultaneously.

2, the described electric melting magnesium furnace automaton of claim 1, it is characterized in that in operating desk and device switch board, five air switches, ten relays, two buzzers, a contactor, six noncontacting switches, an analog quantity switch boards, three groups of current sensors, two Switching Power Supplies and one group of PLC being set.

3, the described electric melting magnesium furnace automaton of claim 1 is characterized in that the configuration of PLC is as follows: three of one, 8 switching value output modules of one, 8 switching input modules of host module S7214, one of three tunnel analog quantity input module.