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Electric automation control system in blast furnace

AbstractCombining with the actual situation of 680M3 blast furnace electric automation instrument control system of Qinhuangdao Baigong Iron and Steel Co., Ltd, the paper emphatically expounds the reasonable application of Yiwei UN200 and UN300 series PLC expansion modules in charging system, hot blast stove system, bag dust removal system, blast furnace charging and distribution system, body instrument detection system and blower room. System, pump station system and screen monitoring, software function and other successful cases. This paper mainly introduces the design scheme of four sets of PLC system, such as feeding PLC main station, main body PLC main station, hot air PLC main station and bag PLC main station.


I. overall system design concept


According to the blast furnace technology, the general idea of low cost and high performance is adopted in a reasonable way. The automation system adopts the open structure of three-power integration, which creates conditions for the future expansion of the system, and retains the interface ability of the regional computer and the whole factory management computer.

According to the characteristics of blast furnace system decentralization, the master-slave network structure is adopted: the substation is connected to the master station system through the network line, which reduces the cable consumption, facilitates maintenance and greatly reduces the cost. Such as Yiwei IM153-1 can be used as a single slave station, and can be installed near the distribution room of blast furnace equipment. The cloth bag blowback is designed by matrix. The structure is simple, and the number of module points used is reduced.

The system uses billion-dimensional PLC as the basic control station to complete the control and monitoring of on-site process equipment; the upper operation uses billion-dimensional industrial control computer as the operating station to carry out man-machine dialogue, real-time monitoring of on-site equipment operation and various instrument parameters. In order to ensure the normal operation of the production under various circumstances, the system is mainly automatic, and the upper computer is reserved for each other.


In principle, the selection of automation device adopts the new technology and equipment at present detection level, and considers that the structure of control system is simple, practical and reliable, which fully meets the technological requirements. Reduce investment by ensuring product quality and ensuring that the system meets process requirements and performance as a whole.


2.system configuration


This system can provide service for blast furnace operation and make the controlled equipments operate conveniently and centrally on the computer of the main control building, and record the operation of these equipments truthfully.


1)automatic monitoring system:


A1 network structure adopted


The upper computer adopts industrial Ethernet, which fully meets the requirement of large amount of data transmission between upper computers; the PROFIBUS-DP fieldbus is used between PLC and remote station to meet the real-time and reliability of field data transmission; the network block diagram is as follows:



There are mainly six industrial control computers as operating stations, which are hot air, bag, skilled operator, main instrument, ore trough feeding, furnace top equipment, and can be reserved for each other.


PLC has four sets of Siemens 400 series main PLC system, feeding PLC main station, main body PLC main station, hot air PLC main station, cloth bag PLC main station, under the respective expansion module to complete the system control and data acquisition. Data exchange between PROFIBUS-DP network and operation station is completed.


B. hardware and software components


PLC selects the high performance and low cost module structure of Yiwei 200+300.


Computer operation console: stainless steel surface console


Programming software selects STEP7 V5.4, and configuration software selects my WINCC 6 SP3.


  

3. Hot stove control system


The blast furnace is equipped with three hot blast stoves, which are mainly responsible for combustion, heat storage, cold air heating, and hot air into the blast furnace. Because a hot blast stove is intermittent heat exchange, and the blast furnace needs continuous hot air, so the three hot blast stoves work periodically, including combustion, blast stove, blast three processes.


Hot blast stove sequence control system has the following operating modes: automatic, semi-automatic, CRT manual mode, side box operation


Introduction to the working state of hot blast stove


A hot blast stove can be converted from "blowing" to "smoldering" to "burning" or from "burning" to "smoldering" to "blowing".


"Air supply" means that the hot stove is pressurized and both the cold air valve and the hot air valve are opened. All other valves are closed (excluding mixed air shutoff valves and heat exchanger valves).


"Combustion" means that the hot stove is decompressed, the cold air valve, the hot air valve and the cold air charging valve are closed, the exhaust gas pressure equalizing valve is opened, and the combustion-supporting air and gas are introduced into the hot stove.


"Suffocation" means that all the valves of the hot stove are closed, but the pressure control is still in operation, and a hot stove is ready to be charged or equalized at any time.


Working system of hot blast stove:


Under normal conditions, the hot blast stove adopts the parallel air supply, or the two-burning-one-feeding system, and the abnormal operation is one-burning-one-feeding system.


Each hot-blast stove can automatically switch between the three states of "stove", "air supply" and "combustion". Each valve switch is controlled by PLC program. After issuing the order of changing stove, the hot-blast stove equipment carries out interlocking action according to the sequence of technological requirements.



4. Dry type purification control system for blast furnace gas


The blast furnace gas dedusting facility is the auxiliary facility of the blast furnace. Its purpose is to purify the blast furnace gas and improve the quality of the gas. After the blast furnace gas is dusted by gravity dust collector, it enters the lower part of the main box of cloth bag. When the gas passes through the cloth bag, the dust carried by the gas is intercepted by the cloth bag, and the filtered and purified gas is transported to the hot blast stove or the gas pipe network through the high pressure valve group for users to use. Dust filtered by bag filter is washed by pulse valve and falls into ash storage bin; unloading valve is opened, output by scraper, and sent to high ash bin by bucket lift.

1)This set of facilities has designed three kinds of back-blowing methods, time back-blowing (set time to), pressure back-blowing (pressure difference is higher than the set value), manual back-blowing.

2) The dust removal system consists of two control processes: back-blowing and dust discharge, all of which can be controlled manually, semi-automatically and automatically.

The automatic blow back mode is: differential pressure reverse blow and timing blow. Differential back-blowing is when the box differential pressure is higher than the set differential pressure value (3KPA), automatic back-blowing starts when the timing time reaches the set back-blowing time.

A. When barren clean gas main pipe pressure difference reaches 6 ~ 8Kpa (can be set) to carry out anti blow. At the same time, the timing blow option is selected, and the cloth bag is blowback through the same period.

B.The backblowing time of the chamber is 10-20 seconds (adjustable). The backblowing sequence is N1, N2, N3... N10. The nozzles on the air drum are also sequentially operated n1, n2, n3.... N14 until all the 10 chambers are blown back, and the backblowing process is over.

C. box reverse blow by off-line blowback. When the total pressure difference of clean waste gas reaches a set value of 6Kpa, the inlet and outlet butterfly valves of the working box body are closed first, and then the back blowing is carried out. Immediately after the blowback, the butterfly valve of the inlet and outlet is opened, and the reverse blow of the next box is carried out in turn.

D. each bag has a jitter of 2 times per time (adjustable).

E. automatic operation of discharging ash is: timing ash unloading. Set the discharging time, automatically start the discharging bucket lifter, hanging plate machine, according to the technical requirements to open the selected discharging box on the equipment (up discharging valve, down discharging valve, impeller feeder, ash bucket plug removal device pulse valve), generally set 3/24, automatically complete the discharging operation.

The action sequence of the lower part of the intermediate warehouse:

When the upper part of the N1 cabinet is discharged, the middle bin is discharged. The common equipment, i.e. inclined tube vibrator bucket lifter scraper conveyor, is first opened. Open after completion: N1 box electric feeder N1 box lower electric ball valve N1 box middle bin wall vibrator. After a delay of 30 seconds, close the lower part of the intermediate store.

The order is: the storehouse wall vibrator in Guanzhong warehouse, the lower part of the N1 box, the electric ball valve, the electric feeder.

After the bottom of the N1 box is unloaded, the bottom of the N2 box will be unloaded with N1 box. Followed by N3 boxes, N4 boxes, N5 boxes... N8 box.

When the bottom of the N10 box is discharged, the public equipment is closed. The order is:

Scraper conveyor, bucket elevator and inclined tube vibrator.


2)The operation sequence of the lower part of the high ash bin is all machine side operation, and the other equipment is controlled by PLC. :

Opening: humidifier ash discharging machine, electric ball valve, silo wall vibrator.

Closing: wall wall vibrator to electric ball valve to humidifier and ash disposal machine.


5. Charging system for blast furnace

The charging part of the blast furnace consists of two parts: the ore trough weighing and the top of the furnace. The two parts are connected by the charging truck. The charging function is completed by the coordinated action of the ore trough, the charging truck and the furnace top equipment according to the technological setting.

All kinds of materials are screened by vibrating screen and then directly loaded into the weighing bucket. Then a weighing bucket is loaded into the truck. The powder under the screen is transported to the silo by crushing belt, waiting for the truck to go out. The skip is driven by the main hoist to convey the ore to the top loading equipment and reach the parking space after 2 stages of speed change. The quality of each bin is changed at any time according to the requirements of the formula, and the operation of weighing and loading is automatically completed.

1)Equipment composition

The 680 M3 blast furnace is equipped with double-row storage tanks, which store sinter, pellet, coke and miscellaneous ores respectively. Four coke tanks, six sintering tanks, four pellets and four miscellaneous ores are arranged in pairs under the tanks. The top of the furnace consists of hopper, stopper valve, upper sealing valve, lower sealing valve, material flow valve, rotating mechanism, tilting mechanism, material tank, pressure equalizing valve, pressure equalizing and releasing equipment.

2)feed cycle control system, the most commonly used for the following two systems.

Two car value: OC or CO

Four car value: OO CC or CC OO

Description: O stands for sinter, pellet and miscellaneous ore; C represents coke.

Several different charging systems are combined to form batch cycle, continuous cycle feeding, to meet the continuous production requirements of blast furnace.

3). Control Requirements: According to the technological requirements, display and control the relevant technological parameters of the trough, charging and furnace top equipment system, and record the trend of the relevant parameters. It includes 14 electronic weighing records, material level measurement, control and display of TRT and various signals of blast furnace and TRT.

Temperature detection of water cooling system: when the temperature difference between inlet and outlet of chute gear box is greater than 5, alarm signal is issued, prompting the relevant personnel to check water flow and blast furnace top temperature; when the temperature difference is greater than 50, immediately check the water cooling system.

When the difference between the tank pressure and atmospheric pressure is less than 20KPa, the interlock signal is sent out, and the upper sealing valve is opened by an electric power professional; when the difference between the tank pressure and the furnace top pressure is less than 20KPa, the interlock signal is sent out and the lower sealing valve is opened.


6.The air tight box is cooled with nitrogen flow control valve to control the opening.

Blast furnace body instrumentation control system

The top-down blast furnace consists of five parts of the throat, furnace body, furnace belly, hearth, furnace foundation and related water system. All meter points are connected to the data collector and transmitted to the upper computer through communication.

The main tasks of blast furnace process detection and control are: collecting temperature, pressure, flow and other data, adjusting and controlling the pressure reducing valve group, monitoring furnace reactions, and protecting furnace body and equipment.

1) water control at the top of the furnace

When the temperature of the gas riser is too high, it will alarm and open the top.

2) top gas pressure control

The pressure control system of blast furnace top gas regulates the opening of pressure reducing valve group after bag filter to maintain the stability of top gas pressure.

3)leak detection and drainage temperature measurement


In order to protect furnace safety, leak detection is a very important test item. Measuring the inlet and outlet flow difference of cooling water in tuyere, measuring the temperature of the tuyere drainage, can check whether the tuyere is intact.

Seven, picture introduction


The screen system is the man-machine interface between the operator and the control system. The operator operates the equipment and monitors the operation of the equipment through the screen. The screen system can set the data, change the operation mode, and display the normal state of the equipment and alarm information to the operator.


The main contents of the CRT display are as follows:


(1) System picture: hot air, cloth bag, mine trough, furnace top, body instrument, furnace head operating furnace, furnace top instrument, etc.

(2) control setting screen: setting of ingredients, roof chute angle and material flow opening parameter setting.

(3) failure monitoring screen: real-time display of fault signals, prompting operators to take corresponding measures.

(4) alarm record: record the failure alarm of each equipment and meter.

(5) report record: real-time record of production parameters.

The following main picture is introduced.


7. Loading screen:


Including the entire poplar and furnace top equipment, which are mainly feeding trolley, left and right probe, plunger valve, top density, bottom density, rotating distribution device, pressure equalizing valve, release valve and so on. Manual and automatic conversion can be realized in production at any time, all kinds of operation and faults have different colors to display, features 1, car inflection point, unloading level and other deceleration point parking space can be adjusted according to production 2, rotating cloth angle and speed can be set directly through the screen, to meet the production process of various cloth mode 3, in the maintenance or Under the training of new employees, simulation production can also be done by setting various data in the picture.

图片20-a4f4a7b5-9856-4143-8854-06066aea0be8.png

The instrument on the top of the blast furnace is very important for ensuring the normal equipment of the furnace top.

2)mine slot picture


It mainly includes belt, hopper, vibrating screen operation, stop, fault indication and operation. The weight of various materials can be set in advance in this screen, and the automatic feeding can be completed by adjusting the periodic table according to the requirements of various batches under the furnace head. It can also transfer individual control to field operation by machine-side switch. There are manual (green) and automatic (purple) instructions in the screen. There are also periodic table subgraphs. As follows:


Adjust the recipe and generate the recipe automatically. As follows:

Production report record screen, real-time production cost control, as follows:

 

3) Hot blast stove screen

This screen can realize the operation of combustion-supporting fan, pressure regulating valve group, combustion-supporting regulating valve, mixing air valve, cold air valve, hot air valve, release valve, cold air pressure equalizing valve, gas regulating valve, air regulating valve, air shutoff valve, gas shutoff valve and various process valves and display instrument parameters. It can automatically accomplish all stages of hot blast stove conversion to achieve automatic air supply, braising and burning. Various valves in the screen can be point-operated, regulating valves are automatically adjusted by entering predetermined values or clicking on the scroll bar. Figure:



4) bag dust screen

It includes pulse valve, up and down ash discharging valve, release valve, top gun, down gun, ash conveyer, bucket lifter, inlet and outlet butterfly valve and inlet and outlet blind valve, and displays the running state of the equipment and the parameters of various instruments. With the mouse click each valve can automatically pop up the control menu, pulse valve for dynamic display, can be found at any time because of frequent action and damage to the solenoid valve. Pulse time and box selection can be set according to requirements.

Automatically purge under automatic condition, and start from 1 to 8. If there is a problem in a box, it will automatically jump over the box to execute down. The picture is as follows:



5) It is the key for the production and high production of the blast furnace to adjust the furnace condition reasonably through the screen parameters


6)The appearance of the body instrument. The BF instrument is to monitor whether the blast furnace lining is normal, mainly including water temperature and pressure.


8. concluding remarks


Each action and state of the automatic control system of blast furnace is controlled by PLC, which not only meets the requirements of a large number of presses, switches and position detection points required by centralized control mode, machine-side control mode and two-way control mode of each equipment, but also chooses a reasonable configuration method according to different technological requirements. The master-slave structure of the network, the matrix structure of the bag blowing back, etc., and the PLC industrial LAN can be composed of interface components and computers to realize network communication and network control. The electric automation instrument control system of the blast furnace can be conveniently embedded into the production line of the iron and steel industry.



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