Transformation of sintering machine batching contr

Transformation of sintering machine proportioning control system based on Fieldbus

Abstract: This paper introduces the capacity expansion transformation of sintering automatic proportioning of Xingang based on PROFIBUS-DP fieldbus control, which makes full use of the openness of fieldbus. The reformed control system is more standardized and reasonable, and the degree of automation is greatly improved, which greatly improves the sinter quality and production efficiency

key words: PROFIBUS-DP fieldbus frequency converter proportioning

preface

sintering proportioning is the core of sintering production, and it is also an important part of the whole iron and steel production process. Reasonable proportioning of various materials is the key to improve the grade of sinter. The distributed process control system based on PROFIBUS-DP fieldbus is used in the original batching workshop of sintering machine of Xingang to realize microcomputer automatic batching. PROFIBUS field bus is an open, digital, two-way transmission and multi branch communication network applied to the production site to connect intelligent field devices and automation systems. It can realize rapid communication between devices

due to the technical transformation project, this batching workshop should also be used for a new 90fl2 sintering machine. In this way, the load is increased, and the requirements cannot be met from the outdoor raw material bin, drag belt weigher to the indoor frequency converter and control system. Therefore, on the basis of fieldbus control, it is expanded, transformed and upgraded to establish a high-performance automatic batching system

1 composition principle

there are 9 electronic belt weighers for dragging materials in the batching workshop (1 support-9 support). The rated power of the rotating motor of 1 support, 3 support, 7 support, 8 support and 9 support is 2.2kW, and the rated current is 5.0A. The rated power of the motor of 2 support, 4 support, 5 support and 6 support is 3.0kw, and the rated current is 6.8a. The motor drives the weighing belt to rotate, and the material layer is uniform. The faster the motor rotates, the greater the material flow, and the higher the proportion. Conversely, The slower the motor rotates, the smaller the material flow and the lower the proportion. Each motor is driven by a frequency converter, and the frequency of the frequency converter is controlled by PLC through Profibus-DP Field bus. PLC calculates the actual flow of each material according to the load and instantaneous flow of each material automatically collected, and compares it with the set value to complete the closed-loop adjustment. The system principle is shown in Figure 1

according to the on-site experience, the electronic belt scale only retains the primary weighing instrument, cancels the secondary instrument, and is converted by PLC; Cancel the speed sensor and convert it by frequency conversion. The weighing resistance bridge signal is input into the PLC template after isolation, amplification and linearization. In this expansion and reconstruction, a complete set of electronic belt weighers and frequency converters with 2-brace, 3-brace and 9-brace are added. Among them, 9 supports are bidirectional rotation, bidirectional metering, bidirectional variable frequency speed regulation and bidirectional control

2 system composition

this set of control system can use pp-lgf material instead of metal and nylon material, and adopts a distributed structure, which is composed of equipment control level and process monitoring level. Siemens PLC with high cost performance is selected as the main control station, and the system is connected with the distributed field devices through Profibus-DP Field bus. The process monitoring operation station adopts configuration software to monitor the system in real time, and its system composition is shown in Figure 2

the equipment control level includes the main control station, 1-9-support electronic belt scale frequency converter, and the control station. Among them, derisive station, 2-pole, 3-pole and 9-pole frequency converters are added for this transformation. According to the process needs, the digital quantity input template of the main control station adopts 16 channel AC220V and 32 channel DC24V, and the digital quantity output template adopts 32 channel DC24V; Omron relay with reliable performance shall be selected for low-voltage electrical equipment; Seven frequency converters adopt MMV 440 of Siemens company and are equipped with PROFIBUS-DP interface board option. All PLCs and frequency converters, including the main control station, are directly connected to various devices on site (such as sensors, motors, electrical devices, etc.) to realize the analog signal detection of 9 hauling belt scales and the frequency conversion control of motors. The e'ip.00 station realizes the electrical control of the two coal blending and outer coal rolling rollers after capacity expansion, and the physical flow control of 2-brace, 3-brace and 9-brace belt weighers, especially the two-way measurement and two-way frequency conversion control of 9-brace belt weighers, In addition, it also realizes the acquisition and control of signals such as start stop and interlock of multiple common belts and high-voltage motors

the process control level (i.e. the process monitoring operation station) can not meet the requirements of rapid communication after control because the previous equipment speed is slow, so this transformation has carried out a complete set of equipment upgrading, which is composed of a P4 Advantech industrial control computer, and the Advantech industrial control computer passes C_$ The 5611 communication card communicates point-to-point with the MPI interface of cpu315. Considering the reliability and friendliness of man-machine interface, the industrial computer adopts the windows 2ooo software platform, and the upper computer adopts the FameView configuration software, which is responsible for monitoring and man-machine dialogue. It has the functions of process flow monitoring, alarm recording, real-time trend, historical trend, report printing, etc. the operators input the batching formula, modify the formula, consult the process parameters, and monitor the production process through monitoring operations. The programming application software adopts step V5.2 to complete hardware configuration and lower computer software programming, and realize all process control, data acquisition, automatic adjustment, accident handling, alarm and other work

3 software implementation

because the original design software is not standardized, sometimes when the peripheral equipment is replaced, the model parameters are inconvenient to input, and the amount of software changes during this expansion and transformation is relatively large, so the whole set of lower computer monitoring software is redeveloped, with unified internal parameters and variables, clear interfaces, standardized and open design software, which is easy to expand and upgrade the whole system

the focus of this software design is the control of the drag belt scale, that is, the instantaneous flow P and R are calculated according to the instantaneous weight of the weighing sensor, the measuring section, the belt speed (proportional to the motor speed), the gravity coefficient and other parameters. Compared with the flow sp set by the monitoring station, the motor speed (i.e. the output frequency value of the frequency converter, with a range of 0 50Hz) is calculated by using the PID algorithm module (fb41) of Siemens programming software stef7, Real time tracking and closed-loop adjustment. When each belt scale starts to start and enter the regulation, the instantaneous value of the frequency converter will change from the maximum value of 50Hz until the flow setting is met. In the process of operation, sometimes it is necessary to change the set flow SP value, the zero point and coefficient of a belt weigher, so it needs to be recalculated to make the coal price have an unexpected rapid rebound adjustment. The flow regulation software flow is shown in Figure 3

4 system features

based on PROFIBUS_- After the expansion and reconstruction of the sintering proportioning system of DP fieldbus communication network, the control system has complete functions, realizing the automatic control of the start, stop, interlocking protection, weighing and adjustment of several belts, belt scale motors and rollers, and formulating guidance for the innovative development of new energy vehicles. The system mainly has the following functions:

1) it has two working modes: manual and automatic. During manual operation, each belt and belt scale shall be started, stopped, accelerated and decelerated by the operator according to the process requirements, and can also be electrically interlocked. When automatic, the upper computer of the system sends the given value according to the total flow and the proportion of each material, and automatically starts, accelerates and decelerates the belt scale motor. The start and stop of all belts and rollers are realized by logical interlocking control

2) when the ratio changes, the internal PID regulator operates, the frequency of the frequency converter changes stably, and the speed regulation is smooth

3) cancel the belt scale instrument and speed measuring sensor, and the MV signal of the weight measuring sensor directly enters the PLC after processing, with the functions of signal zero calibration, automatic skin calibration and automatic adjustment system

4) PROFIBUS-DP fieldbus has the ability of high-speed communication, which can quickly collect and transmit field data, so that the signal is not delayed and distorted, and has strong expansion ability

5) to prevent turnover, stop all belt scale motors immediately while the main aggregate belt is stopped; When the aggregate main belt is started normally, it will automatically delay the start of the last operation (selected) according to the batching system. Therefore, plastic granulation is an industry silo that will never be eliminated

6) it has cumulative consumption of materials, lifelike animation display of all equipment actions, reliable interlocking between all equipment, high safety, simple and convenient operation

this set of control system has openness, standardization, interconnection, interoperability and rich hardware and software resources, so that the monitoring operation station can be used as a monitoring station to display monitoring images, and also as an engineer station to call up ladder logic diagram at any time, debug programs and find faults, which is convenient and fast

5 effect

this expansion and reconstruction makes full use of the openness of fieldbus, and carries out system docking and debugging during the interval of equipment maintenance, which does not affect normal production. The transformed automatic control system is more reasonable and standardized. The operation proves that the PROFIBUS-DP fieldbus control system is reliable in hardware, has strong anti-interference ability and advanced technology, and realizes the full automation of the sintering batching production process. Using PROFIBUS-DP bus control, the internal PID regulation is realized, and the speed regulation of the frequency converter is smooth, which plays an important role in protecting the production equipment. PROFIBUS-DP reduces a lot of hard wiring, thus simplifying the control system. Compared with relay logic control, it reduces the failure rate, improves the reliability of the system, and batching is accurate. The batching control error of the system is reduced from the original 10% to about 1.5%-2%, which provides a full guarantee for the stable high yield of sintering and the improvement of sinter quality

6 references

[1] song Bosheng. Programmable control system configuration · programming · joint. Beijing: China Labor press, 1998.194-225.

[2] Zhang Guiling. Brief discussion on Fieldbus and its impact on the field of automation. Microcomputer information, 20O3 (4):14. (end)